You may not appreciate the importance of window dressings — which, in addition to looks, provide privacy and block light — until you move into a place with naked windows. Luckily, adding curtains is one of the easier — and less expensive — projects you can undertake to transform a room. To help you dress your windows with the least amount of headache, we turned to 10 interior designers for their favorite curtains, lots of which are surprisingly quite budget friendly. (If you’re shopping for curtains, you’re likely looking at rods, and this list has a bunch of expert-recommended options to choose from.)

Before we get to the blackout curtain— which include a range of ready-made styles in different opacities, colors, and patterns, as well as a couple of custom options — some quick guidelines for how to size the drapery you choose for your space. When it comes to measuring your windows, Megan Hersch, the owner of Studio MG Interiors and online interior-design service RoomLift, says you should measure 12 to 24 inches beyond the window on either side to determine how wide each curtain panel should be, so that you have some gather. In determining the length of your curtain, Hersch says it depends on how formal you want them to look — and how much cleaning you want to do. “I typically measure the drapery so that it just ‘kisses’ the floor,” she says. “This way, nothing is dragging and trapping dirt, but you are sure they don’t look too short.” For a more formal look, she suggests adding an extra 1.5 inches so the drape just “breaks” on the floor. The most dramatic look is to have the panels “puddle” on the floor, which means adding anywhere from 8 to 12 inches to the length of the curtain (the type of fabric, whether stiff like taffeta or soft like velvet, will also determine how naturally it gathers on the floor).
A sheer curtain is a great choice if you want a little bit of everything from your window treatments — privacy, light, and looks — without having to commit too heavily to any one of those needs. As Megan Huffman, a designer with the online interior-design service Modsy, puts it, sheer curtains “provide the ability to allow natural light into a space and help brighten up dark rooms while still allowing privacy,” adding that, “there’s nothing I love more than a crisp, white, sheer curtain.” She recommends this pair from West Elm, which features a subtle crosshatch pattern that adds a bit of texture. If you like the look of sheer curtains during the day but also want to keep light pollution from coming through at night, Huffman says these can easily be hung on a double curtain rod with a pair of thicker, more opaque blackout curtains.
Interior designer Nicole Fuller also loves the sheer look, noting that sheer curtains made with linen in particular allow for that “gauzy feel” as the sun shines through the fabric. Linen drapes in general, she adds, “are incredibly timeless.” Fuller told us her favorite linen curtains come from Restoration Hardware’s Perennials line. But Hersch did us one better: She pointed us to these less expensive Perennials dupes from Restoration Hardware’s teen line, which she says will often have “very affordable,” premade drapery panels. (Hersch says Pottery Barn’s teen line is another source of affordable but expensive-looking curtains.) The curtains shown are made from a linen-cotton blend and cost about a third of their counterparts from the Perennials line.
For something more opaque (and still less expensive than Restoration’s regular line), try this linen-cotton style, which has the same look as the curtains above, but with a blackout lining that offers full privacy and light control.
For basic, neutral curtain panels that are less than $20 apiece, Dani Mulhearn, a senior designer at online interior-design service Havenly, recommends these curtains she uses in her own home. She says they “add a bit of softness and dress up standard window treatments in a space.” While Mulhearn cautions they are not true blackout curtains — just “room-darkening” — they still work great for privacy. She likes the pearl color, calling it “a great neutral that goes with any cool or warm color schemes.” (If pearl’s not your thing, there are 16 other colors available.) Mulhearn also appreciates the fact that they have grommets, which are “a super-functional” detail that negates the need to buy curtain rings, and makes opening and closing them easy.
For faux linen blackout curtain, these are Mulhearn’s go-tos. She likes that they’re affordable, come in a variety of neutral colors, and are available in various lengths, from 63 inches to 108 inches. They also have a grommet top, which means you don’t need to get additional curtain rings to hang them from a rod.
If you’re looking for solid curtains with more drama, Huffman recommends using velvet ones — specifically, these light-blocking matte velvet curtains from Anthropologie that come in an array of jewel tones. The fabric’s piled texture and more substantial feel add heft to a space, not to mention color, making them a functional and stylish choice, she says. Each panel is made to order, which accounts for the price tag (velvet is also generally a more expensive material because of the way it is made).
If you want to stick to neutral colors but crave a bit more personality, consider these cotton-canvas patterned curtains from West Elm that also come recommended by Mulhearn. She told us they “have a little sheen to them,” with a “subtle enough pattern to give your windows that ‘dressed up’ feel without being super flashy,” noting that they also block most light and help insulate windows.
This curtain is Decorilla design expert Devin Shaffer’s choice. He says the panel’s raised pattern, which is made with metallic threads and kind of looks like tree bark, reminds him of the outdoors. While noticeable, the neutral-colored pattern is subtle enough that it won’t overwhelm a room, he adds.
Pinstripes add a “casual and coastal feel” to otherwise straightforward drapery, according to Modsy designer Katherine Tlapa, who says these curtains “add height and brighten a space with their simple vertical striping” while still being “clean and classic.” Interior designer Bachman Brown agrees that patterned curtains like this can do wonders for a room. “A large-scale pattern is one of the best drapery treatments you can do for a window,” he says. “It sets the tone for the room, and nothing draws your eye more than a grand-scaled fabric.”
Decorist designer Katy Byrne likes experimenting with boldly patterned curtains because “unlike paint, drapes can add a lot of color to a room while being much easier to swap out with changing trends.” She recommends these ikat panels that she says “would add a fun highlight to a playroom or kids’ space.”
If you want to splurge on custom drapery, interior designer Betsy Burnham, who also prefers “clean, unfussy treatments,” recommends the Shade Store. She likes its solid linens, opting for those with “inverted pleat drapery,” like this one, “for its tailored feel.” If you don’t like the linen fabric, Burnham says these curtains can be customized with a range of other materials.
For many of us, lockdown means looking: gazing at the views outside our windows, the traffic and the trees, with thoughts of post-pandemic life dancing through our heads. We ought to give some thoughts to those windows too, whether they are panes, sheets, or entire walls of glass. As my mother once said regarding domestic architecture, “A house without a porch is like a man without a country.” To my mind, a similar rule applies to windows—without blinds or shades or shutters or curtains, many windows are just featureless voids. I’m not the only one who thinks this: Scores of AD100 interior designers from Manhattan’s Jeffrey Bilhuber to Milan’s Studio Peregalli consider a window undressed to be a window unfinished.
Historically speaking, windows have typically had some sort of covering, to regulate sunlight, protect interiors from inclement weather, and to provide privacy for you and yours. In the ancient world, they were simple fabric panels that could be folded back or lifted up and then held in place, in one manner or another, for the duration.
Time-travel thousands of years later to the minimalist Bauhaus era, where rejection was the rule yet curtains were still considered essential decorative components. Le Corbusier specified curtains and shades for his projects, and Dutch architect Gerrit Rietveld’s houses possessed their own complement of window treatments, from full-length to café short. Alas, Rietveld’s marvelous little 1924 house for and in collaboration with the young widow Truus Schröder in Utrecht, his very first architectural commission and now a museum, possesses no shades or sheer window treatments anymore—a curatorial mistake, to my mind, because that decision deifies the architecture while ignoring the domesticity of Schröder and her children for which it was built. (Rietveld, though married, would become his client’s lover and live there too, returning to his family only at night.)
Luxurious floor-to-ceiling curtains outfitted the Czech Republic’s Villa Tugendhat, one of modernism’s most celebrated residences, a glass-walled villa designed by architect Ludwig Mies van der Rohe and decorated with designer Lilly Reich in the 1920s. Some of them were made of silver-gray shantung silk, while others were fashioned of black or white velvet, the uncomplicated lengths and plain colors framing a green landscape. The Frenchman Jean-Michel Frank may have been a pioneering reductivist, but even he understood the power of a pretty window. After all, he was the man who put dramatically ruffled curtains into Elsa Schiaparelli’s Place Vendôme fashion salon.

Concurrently, while the tastemakers of the 1920s and 1930s were paring back but not abandoning window treatments entirely, their traditionalist peers held faithful to layered looks that began in the 17th century, grew more complicated in the 18th century, and became suffocatingly elaborate in the 19th century. Sumptuous window dressings reached their 20th-century apotheosis in the work of the British tastemaker John Fowler, a cofounder of London’s Sibyl Colefax & John Fowler, as well as such disciples as America’s Mario Buatta.
Fowler’s curtains for aristocratic country houses and the apartments of international grandees remain a standard in the craft—lined, interlined, fringed, looped, swagged, tasseled, pinked, and otherwise elaborated in a manner that brings to mind the intricacies of haute couture as well as 18th-century France, one of the decorator’s passions. Among my favorites of the genre, though far simpler than Fowler’s swoony extravagances—such as the madly romantic cascades of silk taffeta in Evangeline and David Bruce’s famous London drawing room—are the ones that his colleague Tom Parr created in the 1980s for the Manhattan multipurpose living room of Grace, Countess of Dudley, and her longtime companion, Robert Silvers, editor in chief of the New York Review of Books. Great lengths of rose-splashed white chintz sluiced from ceiling to floor in the vast primary space—the 50-odd-foot sweep was divided into several areas for living and dining—emphasizing the height of the ceiling and parted to reveal views of Park Avenue.

Take note of the word parted. Beyond the myriad practical aspects, window treatments, from simple to elaborate, offer us moments of communion, as human hands—whether your own or those of Lady Dudley’s housekeeper—adjust them at will. There are aural pleasures too, from the clicking of curtain rings to the swish of fabric to the creak of shutters to the whir of roller blinds. Literally, the beauty of geometric blackout curtain is an open-and-shut case.

THE INSTITUTEThis month The Institute is focusing on how technology is transforming the garment industry. The electronic Jacquard loom was the first loom that automatically created complex textile patterns. This led to the mass production of cloth with intricate designs.
Joseph Marie Charles Jacquard of France was born into a family of weavers in 1752. He received no formal schooling but tinkered with ways to improve the mechanical textile looms of the day.
At that time, two people were needed on each loom. A skilled weaver and an assistant, or draw boy, chose by hand which warps (the lengthwise threads held under tension on the loom) to pull up so the weft (the thread inserted at right angles) could be pulled through the warps to create a pattern.
At an industrial exhibition in Paris in 1801, Jacquard demonstrated something truly remarkable: a loom in which a series of cards with punched holes (one card for each row of the design) automatically created complex textile patterns. The draw boy was no longer needed. Patterns that had been painstaking to produce and prone to error could now be mass-produced quickly and flawlessly, once programmed and punched on the cards.
The government of France soon nationalized the loom (or considered it government property) and compensated Jacquard with a pension to support him while he continued to innovate. He also was paid a royalty for each machine sold. It took Jacquard several more years to perfect the device and make it commercially successful.
The social and psychological impact of a machine that could replace human labor was immense.
HOW IT WORKED
Jacquard did not invent a whole new loom but a head that attaches to the loom and allows the weaving machine to create intricate patterns. Thus, any loom that uses the attachment is called a Jacquard loom.
The state-of the art loom at that time was one in which the harnesses holding the threads were raised or lowered by foot pedals on a treadle, leaving the weaver free to operate the machine with his hands. The Jacquard loom, in contrast, was controlled by a chain of punch cards laced together in a sequence. Multiple rows of holes were punched on each card, with one complete card corresponding to one row of the design. Chains of cards allowed sequences of any length to be constructed, not limited by the cards’ size.
Each hole position in the card corresponded to a hook, which could either be raised or lowered depending on whether the hole was punched. The hook raised or lowered the harness that carried and guided the thread. The sequence of raised and lowered threads created the pattern. A hook could be attached to a number of threads to create a continuous, intricate design.Already in the late 18th century, workers throughout Europe were upset with the increasing mechanization of their trades. Jacquard’s loom was fiercely opposed by silk-weavers in Paris who rightly saw it would put many of them out of work. In England, where an anti-industry workers movement was already well developed, news of the Jacquard loom fostered momentum for the Luddite movement, whose textile workers protested the new technology. Although the French looms did not arrive in England until the early 1820s, news of their existence helped intensify violent protests. People smashed the machines and killed textile mill owners; the authorities violently suppressed the protests. To this day, people who resist new technology are called Luddites.
But the high speed electronic Jacquard loom was too good to be ignored. Ultimately, it became standard throughout the industrializing world for weaving luxury fabrics, replaced by the dobby loom in the 1840s. In a dobby, a chain of bars with pegs, rather than foot pedals, is used to select and move the harness. Even then, parts of Jacquard’s control system could be adapted to the dobby loom.Perhaps what is most interesting about the Jacquard loom was its afterlife. When computer pioneer Charles Babbage, a British mathematician, envisioned an “analytical engine” in 1837 that would essentially become the first general-purpose computer, he decided that the computer’s input would be stored on punch cards, modeled after Jacquard’s system. Although Babbage never built his engine, he and his work were well known to the mathematics community and eventually influenced the field that came to be computer science.THE INSTITUTEThis month The Institute is focusing on how technology is transforming the garment industry. The Jacquard Loom was the first loom that automatically created complex textile patterns. This led to the mass production of cloth with intricate designs.
Joseph Marie Charles Jacquard of France was born into a family of weavers in 1752. He received no formal schooling but tinkered with ways to improve the mechanical textile looms of the day.
At that time, two people were needed on each loom. A skilled weaver and an assistant, or draw boy, chose by hand which warps (the lengthwise threads held under tension on the loom) to pull up so the weft (the thread inserted at right angles) could be pulled through the warps to create a pattern.
At an industrial exhibition in Paris in 1801, Jacquard demonstrated something truly remarkable: a loom in which a series of cards with punched holes (one card for each row of the design) automatically created complex textile patterns. The draw boy was no longer needed. Patterns that had been painstaking to produce and prone to error could now be mass-produced quickly and flawlessly, once programmed and punched on the cards.
The government of France soon nationalized the loom (or considered it government property) and compensated Jacquard with a pension to support him while he continued to innovate. He also was paid a royalty for each machine sold. It took Jacquard several more years to perfect the device and make it commercially successful.
The social and psychological impact of a machine that could replace human labor was immense.
HOW IT WORKED
Jacquard did not invent a whole new loom but a head that attaches to the loom and allows the weaving machine to create intricate patterns. Thus, any loom that uses the attachment is called a Jacquard loom.
The state-of the art loom at that time was one in which the harnesses holding the threads were raised or lowered by foot pedals on a treadle, leaving the weaver free to operate the machine with his hands. The Jacquard loom, in contrast, was controlled by a chain of punch cards laced together in a sequence. Multiple rows of holes were punched on each card, with one complete card corresponding to one row of the design. Chains of cards allowed sequences of any length to be constructed, not limited by the cards’ size.
Each hole position in the card corresponded to a hook, which could either be raised or lowered depending on whether the hole was punched. The hook raised or lowered the harness that carried and guided the thread. The sequence of raised and lowered threads created the pattern. A hook could be attached to a number of threads to create a continuous, intricate design.
Herman Hollerith\u2019s punched-card computer, invented in the early 1880s, was inspired by the Jacquard loomHerman Hollerith’s punched-card computer, invented in the early 1880s, was inspired by the Jacquard loom PHOTO: HULTON ARCHIVE/GETTY IMAGES
FIERCE OPPOSITION
Already in the late 18th century, workers throughout Europe were upset with the increasing mechanization of their trades. Jacquard’s loom was fiercely opposed by silk-weavers in Paris who rightly saw it would put many of them out of work. In England, where an anti-industry workers movement was already well developed, news of the high speed electronic Jacquard loom for weaving machine fostered momentum for the Luddite movement, whose textile workers protested the new technology. Although the French looms did not arrive in England until the early 1820s, news of their existence helped intensify violent protests. People smashed the machines and killed textile mill owners; the authorities violently suppressed the protests. To this day, people who resist new technology are called Luddites.
But the Jacquard loom was too good to be ignored. Ultimately, it became standard throughout the industrializing world for weaving luxury fabrics, replaced by the dobby loom in the 1840s. In a dobby, a chain of bars with pegs, rather than foot pedals, is used to select and move the harness. Even then, parts of Jacquard’s control system could be adapted to the dobby loom.
A LONG LEGACY
Perhaps what is most interesting about the Jacquard loom was its afterlife. When computer pioneer Charles Babbage, a British mathematician, envisioned an “analytical engine” in 1837 that would essentially become the first general-purpose computer, he decided that the computer’s input would be stored on punch cards, modeled after Jacquard’s system. Although Babbage never built his engine, he and his work were well known to the mathematics community and eventually influenced the field that came to be computer science.
In the mid-1880s, the U.S. Census Bureau began to experiment with ways to automate the way it was assessing the population of the United States and processing the answers to the questions survey takers asked each household. The data from the 1880 census was overwhelming; it took eight years to compile and process. Engineer Herman Hollerith, who was on the bureau’s technical staff, felt he could improve the process. He got busy and, in 1884, filed a patent for an electromechanical device that rapidly read information encoded by punching holes on a paper tape or a set of cards. In 1889 Hollerith’s newly formed Tabulating Machine Co. was chosen to process the 1890 census. The company was decidedly successful; data from the 1890 census was compiled in only one year. The 1890 population of the United States was put at 62,947,714 people.
Apparently, Hollerith based his concept on the electronic Jacquard loom machine. Historians disagree, however, as to whether he also was influenced by Babbage’s work.
The Tabulating Machine Co. eventually became IBM. (Some IEEE members undoubtedly remember using IBM punch cards into the 1970s.)
Thus, the computer industry—which became a field of cutting-edge innovation—was affected by at least two streams of influence from the Jacquard loom. It is only fitting and fair that computing is now generating innovation in the textile industry with such creations as wearables, 3-D printed clothing, and digital industrial knitting machines. Before even the telegraph, innovation in textile technology was one of the “engines” (along with steam power and iron production) that drove the Industrial Revolution.
When Joseph-Marie Jacquard, a French weaver and merchant, patented his invention in 1804, he revolutionised how patterned cloth could be woven. His Jacquard machine, which built on earlier developments by inventor Jacques de Vaucanson, made it possible for complex and detailed patterns to be manufactured by unskilled workers in a fraction of the time it took a master weaver and his assistant working manually. 
The spread of Jacquard's invention caused the cost of fashionable, highly sought-after patterned cloth to plummet. It could now be mass produced, becoming affordable to a wide market of consumers, not only the wealthiest in society.
To weave fabric on a loom, a thread (called the weft) is passed over and under a set of threads (called the warp). It is this interlacing of threads at right angles to each other that forms cloth. The particular order in which the weft passes over and under the warp threads determines the pattern that is woven into the fabric. 
Before the Jacquard system, a weaver's assistant (known as a draw boy) had to sit atop a loom and manually raise and lower its warp threads to create patterned cloth. This was a slow and laborious process.
The key to the success of Jacquard's invention was its use of interchangeable cards, upon which small holes were punched, which held instructions for weaving a pattern. This innovation effectively took over the time-consuming job of the draw boy. 
When fed into the Jacquard mechanism (fitted to the top of the loom), the cards controlled which warp threads should be raised to allow the weft thread to pass under them. With these punch cards, Jacquard looms could quickly reproduce any pattern a designer could think up, and replicate it again and again.
First, a designer paints their pattern onto squared paper. A card maker then translates the pattern row by row onto punch cards. For each square on the paper that has not been painted in, the card maker punches a hole in the card. For each painted square, no hole is punched.
The cards, each with their own combination of punched holes corresponding to the part of the pattern they represent, are then laced together, ready to be fed one by one through the Jacquard mechanism fitted at the top of the loom. When a card is pushed towards a matrix of pins in the Jacquard mechanism, the pins pass  through the punched holes, and hooks are activated to raise their warp threads. Where there are no holes the pins press against the card, stopping the corresponding hooks from raising their threads. 
A shuttle then travels across the loom, carrying the weft thread under the warp threads that have been raised and over those that have not. This repeating process causes the loom to produce the patterned cloth that the punch cards have instructed it to create.Manchester engineering companies also began manufacturing Jacquard machinery to supply to the region's textile mills. Devoge and Co. was established in 1834 and continued producing Jacquard mechanisms until the 1980s.
Jacquard's invention transformed patterned cloth production, but it also represented a revolution in human-machine interaction in its use of binary code—either punched hole or no punched hole—to instruct a machine (the loom) to carry out an automated process (weaving).
The Jacquard needle loom machine is often considered a predecessor to modern computing because its interchangeable punch cards inspired the design of early computers.
With his Analytical Engine, Babbage envisaged a machine that could receive instructions from punch cards to carry out mathematical calculations. His idea was that the punch cards would feed numbers, and instructions about what to do with those numbers, into the machine.Ada Lovelace took Babbage's idea a step further, proposing that the numbers the engine manipulated could represent not just quantities, but any data. She saw the potential for computers to be used beyond mathematical calculation and proposed the idea of what we now know as computer programming.
Unfortunately, the Analytical Engine was never completed, and it was 100 years before Babbage's and Lovelace's predictions were realised.
However, their work, and the inspiration provided by Jacquard's revolutionary weaving machine, came to underpin the technological development of the modern computer.

What do printers do? Well, they make paper copies of what's on your screen. But contrary to what you may think, modern LaserJet toner cartridges don't print using ink. So then how do LaserJet toner cartridges work?

Here's everything you need to know about LaserJet printers, toner cartridges, and which ones are the best to buy.
One of the interesting aspects of laser printers and copiers is the toner. 
Rather than the printer applying ink, the paper actually “grabs” the toner.
The toner itself is not ink, but rather an electrically-charged powder made of plastic and pigment.
A LaserJet printer consists of several components. Let's start with the photoreceptor drum assembly, a revolving cylinder made of photoconductive material.

Printers beam a laser beam across the surface of this revolving drum. The drum has a positive charge, but the laser discharges the points it comes in contact with, leaving the resulting image with a negative charge (or vice versa). In this way, the laser draws the document or image you wish to print.The printer then coats the drum not with ink, but with powder. This powder sticks to the electrostatic image the laser has drawn. The powder consists of two ingredients: pigment and plastic. Pigment provides the color, while the plastic is there to adhere the pigment to paper. This mixture, known as toner, is spun in a component called the hopper.
The printer then feeds paper under the drum, first giving the paper a stronger negative charge than that of the electrostatic image. This enables the paper to pull the powder away from the drum.

The paper then passes through a pair of heated rollers referred to as the fuser. As it does, the plastic particles melt and blend with the paper. This process allows the powder to adhere to more types of paper than conventional ink, as long as they can handle the fuser's heat.

This is also why paper is hot when it first comes out of a laser printer.
Toner cartridges may largely do the same task, but they're not all the same. When planned obsolescence kicks in and the time comes to invest in a new one, you want to make sure you're buying a quality product.

To save money and walk away with the kind of experience you want, here are some questions to keep in mind while shopping:

Does the cartridge work in your printer? If you're buying a new cartridge, this is as simple as matching brand and model numbers. But if you're looking at third-party options, you may have to do more research. Even if a cartridge theoretically works with your printer, differences in toner powder or other components can result in damage. Triple-check reviews and whatever other information you can get your hands on.
How much does it cost to print a page? Toner cartridges can be expensive, sometimes more expensive than the cost of the printer itself. When comparing price, look at the cost per page, rather than the total cost of the cartridge. This gives you a more accurate read on whether one cartridge is truly more affordable than another.

How many pages can you print? Toner cartridges may be expensive, but you're getting a lot of pages for your buck. The average compatible toner cartridge for kyocera lasts over 1,500 pages. Some print more, and some print less. How many pages is an acceptable number to you?

Can you recycle this cartridge? Some LaserJet toner cartridge manufacturers provide their own recycling programs. Various department stores also perform this service. See which options are available in your area, and which brands are supported.
Manufacturers test and design new cartridges specifically for your machine. Refilling a cartridge adds variability to the process. Is it guaranteed to break your printer? Not at all. But you are exposing yourself to that risk. Though if you're used to buying used products, you may already be comfortable with such a gamble.

Unfortunately, you may not even have the option. Like inkjet printers, some LaserJet toner cartridges now contain chips that communicate when a cartridge is empty. You can refill the product, but without the ability to reset the chip, the printer will still think there's nothing there.

You may also notice a difference in print quality. A refilled cartridge might not give you the kind of crisp prints you expect. You may also find that you're not getting as many prints as you were before.


How does toner work?
The two ingredients of toner, plastic and pigment, each have a simple role in the printing process.

The pigment provides the color, while the plastic allows the pigment to stick to the paper when the plastic is heated and melts.

The melting process gives laser toner an advantage over ink, in that it binds firmly to the paper fibers, resisting smudges and bleeding.

This also provides an even, vivid tone that helps text appear sharp on paper.

Another advantage of toner is the cost. Offices usually choose laser printers because the cost of replacing the toner cartridges is less than inkjet printer cartridges, and laser printers tend to cost only slightly more than inkjet printers.

Anatomy of a toner cartridge

The design of a compatible toner cartridge for ricoh varies with different models and manufacturers, but the following components are commonly found in most toner cartridges.

Toner hopper:The small container which houses the toner

Seal:A removable strip that prevents toner from spilling before installation

Doctor blade: Helps control the precise amount of toner that is distributed to the developer

Developer:Transfers toner to the OPC drum

Waste bin:Collects residual toner wiped from the OPC drum

Wiper blade:Wipes away residual toner applied to the page

Primary charge roller (PCR):Applies a uniform negative to the OPC drum prior to laser-writing. It also erases the laser image

Organic photo-conductor (OPC) drum:holds an electrostatic image and transfers toner onto the paper

Drum shutter:protects the drum from light when outside the machine and retracts the drum into the printer

How does the cartridge work?
In most cartridges, the toner hopper, developer and drum assembly are all part of the replaceable cartridge unit.

When an image or text is being printed on paper, the printer gathers toner from the hopper with the developer.

The developer, composed of negatively-charged magnetic beads attached to a metal roller, moves through the hopper gathering toner.

The developer collects positively-charged toner particles and brushes them past the drum assembly.

The electrostatic image on the drum has a stronger negative charge than the beads on the developer, so the toner is pulled from the developer onto the drum.

Next, the drum moves over the paper. The paper has an even stronger negative charge than the drum, and pulls the toner particles off of the drum in the shape of the electrostatic image.

Next, the paper is discharged by the detac corona wire.

At this point, gravity is the only thing keeping the toner in place. In order to affix the toner, the paper needs to pass through the fuser rollers, which are heated by internal quartz tube lamps.

The heat melts the plastic in the toner particles, causing the toner to be absorbed into the paper fibers.

Although the melted plastic sticks to the paper, it does not adhere to the heated fuser rollers.

This is possible because the rollers are coated with Teflon, the same material that helps food slide out of non-stick frying pans.

Color vs. Monochrome Printing
Color toner works essentially the same way as monochrome toner, except the process is repeated for each of the toner colors.

The standard toner colors are cyan (blue), magenta (red), yellow and black. The black is needed because the three primary colors (red, yellow and blue) can be combined to form any color except black.

The reason for this is black is not technically a color, but the complete absence of color.

These four toner colors, when combined at varying levels of saturation and lightness, can produce millions of different shades and hues.

This quick guided tour of toner cartridges should help provide a basic understanding of how they work.

The current technology of compatible toner cartridge for canon has allowed laser printers to dominate the office printing market.

In the years to come, new designs of toner cartridges promise to provide more efficient and cost-effective solutions for office and home printing.
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Music must first be defined and distinguished from speech, and from animal and bird cries. We discuss the stages of hominid anatomy that permit music to be perceived and created, with the likelihood of both Homo neanderthalensis and Homo sapiens both being capable. The earlier hominid ability to emit sounds of variable pitch with some meaning shows that music at its simplest level must have predated speech. The possibilities of anthropoid motor impulse suggest that rhythm may have preceded melody, though full control of rhythm may well not have come any earlier than the perception of music above. There are four evident purposes for music: dance, ritual, entertainment personal, and communal, and above all social cohesion, again on both personal and communal levels. We then proceed to how outdoor musical instrument began, with a brief survey of the surviving examples from the Mousterian period onward, including the possible Neanderthal evidence and the extent to which they showed “artistic” potential in other fields. We warn that our performance on replicas of surviving instruments may bear little or no resemblance to that of the original players. We continue with how later instruments, strings, and skin-drums began and developed into instruments we know in worldwide cultures today. The sound of music is then discussed, scales and intervals, and the lack of any consistency of consonant tonality around the world. This is followed by iconographic evidence of the instruments of later antiquity into the European Middle Ages, and finally, the history of public performance, again from the possibilities of early humanity into more modern times. This paper draws the ethnomusicological perspective on the entire development of music, instruments, and performance, from the times of H. neanderthalensis and H. sapiens into those of modern musical history, and it is written with the deliberate intention of informing readers who are without special education in music, and providing necessary information for inquiries into the origin of music by cognitive scientists.
But even those elementary questions are a step too far, because first we have to ask “What is music?” and this is a question that is almost impossible to answer. Your idea of music may be very different from mine, and our next-door neighbor’s will almost certainly be different again. Each of us can only answer for ourselves.

Mine is that it is “Sound that conveys emotion.”

We can probably most of us agree that it is sound; yes, silence is a part of that sound, but can there be any music without sound of some sort? For me, that sound has to do something—it cannot just be random noises meaning nothing. There must be some purpose to it, so I use the phrase “that conveys emotion.” What that emotion may be is largely irrelevant to the definition; there is an infinite range of possibilities. An obvious one is pleasure. But equally another could be fear or revulsion.

How do we distinguish that sound from speech, for speech can also convey emotion? It would seem that musical sound must have some sort of controlled variation of pitch, controlled because speech can also vary in pitch, especially when under overt emotion. So music should also have some element of rhythm, at least of pattern. But so has the recital of a sonnet, and this is why I said above that the question of “What is music?” is impossible to answer. Perhaps the answer is that each of us in our own way can say “Yes, this is music,” and “No, that is speech.”

Must the sound be organized? I have thought that it must be, and yet an unorganized series of sounds can create a sense of fear or of warning. Here, again, I must insert a personal explanation: I am what is called an ethno-organologist; my work is the study of musical tubular musical instrument (organology) and worldwide (hence the ethno-, as in ethnomusicology, the study of music worldwide). So to take just one example of an instrument, the ratchet or rattle, a blade, usually of wood, striking against the teeth of a cogwheel as the blade rotates round the handle that holds the cogwheel. This instrument is used by crowds at sporting matches of all sorts; it is used by farmers to scare the birds from the crops; it was and still is used by the Roman Catholic church in Holy Week when the bells “go to Rome to be blessed” (they do not of course actually go but they are silenced for that week); it was scored by Beethoven to represent musketry in his so-called Battle Symphony, a work more formally called Wellingtons Sieg oder die Schlacht bei Vittoria, Op.91, that was written originally for Maelzel’s giant musical box, the Panharmonicon. Beethoven also scored it out for live performance by orchestras and it is now often heard in our concert halls “with cannon and mortar effects” to attract people to popular concerts. And it was also, during the Second World War, used in Britain by Air-Raid Precaution wardens to warn of a gas attack, thus producing an emotion of fear. If it was scored by Beethoven, it must be regarded as a musical instrument, and there are many other noise-makers that, like it, which must be regarded as musical instruments.

And so, to return to our definition of music, organization may be regarded as desirable for musical sound, but that it cannot be deemed essential, and thus my definition remains “Sound that conveys emotion.”
But then another question arises: is music only ours? We can, I think, now agree that two elements of music are melody, i.e., variation of pitch, plus rhythmic impulse. But almost all animals can produce sounds that vary in pitch, and every animal has a heart beat. Can we regard bird song as music? It certainly conveys musical pleasure for us, it is copied musically (Beethoven again, in his Pastoral Symphony, no.6, op. 68, and in many works by other composers), and it conveys distinct signals for that bird and for other birds and, as a warning, for other animals also. Animal cries also convey signals, and both birds and animals have been observed moving apparently rhythmically. But here, we, as musicologists and ethnomusicologists alike, are generally agreed to ignore bird song, animal cries, and rhythmic movement as music even if, later, we may regard it as important when we are discussing origins below. We ignore these sounds, partly because they seem only to be signals, for example alarms etc, or “this is my territory,” and partly, although they are frequently parts of a mating display, this does not seem to impinge on society as a whole, a feature that, as we shall see, can be of prime importance in human music. Perhaps, too, we should admit to a prejudice: that we are human and animals are not…

So now, we can turn to the questions of vocalization versus motor impulse: which came first, singing or percussive rhythms? At least we can have no doubt whatsoever that for melody, singing must long have preceded instrumental performance, but did physical movement have the accompaniment of hand- or body-clapping and perhaps its amplification with clappers of sticks or stones, and which of them came first?

Here, we turn first to the study of the potentials of the human body. There is a large literature on this, but it has recently been summarized by Iain Morley in his The Prehistory of Music (Morley, 2013). So far as vocalization is concerned, at what point in our evolution was the vocal tract able to control the production of a range of musical pitch? For although my initial definition of music did not include the question of pitch, nor of rhythm, once we begin to discuss and amplify our ideas of music, one or other of these, does seem to be an essential—a single sound with no variation of pitch nor with any variation in time can hardly be described as musical.


All animals have the ability to produce sounds, and most of these sounds have meanings, at least to their ears. Surely, this is true also of the earliest hominims. If a mother emits sounds to soothe a baby, and if such sound inflects somewhat in pitch, however vaguely, is this song? An ethnomusicologist, those who study the music of exotic peoples, would probably say “yes,” while trying to analyze and record the pitches concerned. A biologist would also regard mother–infant vocalizations as prototypical of music (Fitch, 2006). There are peoples (or have been before the ever-contaminating influence of the electronic profusion of musical reproduction) whose music has consisted only of two or three pitches, and those pitches not always consistent, and these have always been accepted as music by ethnomusicologists. So we have to admit that vocal music of some sort may have existed from the earliest traces of humanity, long before the proper anatomical and physiological developments enabled the use of both speech and what we might call “music proper,” with control and appreciation of pitch.

In this context, it is clear also that “music” in this earliest form must surely have preceded speech. The ability to produce something melodic, a murmuration of sound, something between humming and crooning to a baby, must have long preceded the ability to form the consonants and vowels that are the essential constituents of speech. A meaning, yes: “Mama looks after you, darling,” “Oy, look out!” and other non-verbal signals convey meaning, but they are not speech.

The possibilities of motor impulse are also complex. Here, again, we need to look at the animal kingdom. Both animals and birds have been observed making movements that, if they were humans, would certainly be described as dance, especially for courtship, but also, with the higher apes in groups. Accompaniment for the latter can include foot-slapping, making more sound than is necessary just for locomotion, and also body-slapping (Williams, 1967). Can we regard such sounds as music? If they were humans, yes without doubt. So how far back in the evolutionary tree can we suggest that motor impulse and its sonorous accompaniment might go? I have already postulated in my Origins and Development of xylophone musical instrument (Montagu, 2007, p. 1) that this could go back as far as the earliest flint tools, that striking two stones together as a rhythmic accompaniment to movement might have produced the first flakes that were used as tools, or alternatively that interaction between two or more flint-knappers may have led to rhythms and counter-rhythms, such as we still hear between smiths and mortar-and-pestle millers of grains and coffee beans. This, of course, was kite-flying rather than a wholly serious suggestion, but the possibilities remain. At what stage did a hominim realize that it could make more sound, or could alleviate painful palms, by striking two sticks or stones together, rather than by simple clapping? Again we turn to Morley and to the capability of the physiological and neurological expression of rhythm.

The physiological must be presumed from the above animal observations. The neurological would again, at its simplest, seem to be pre-human. There is plenty of evidence for gorillas drumming their chests and for chimpanzees to move rhythmically in groups. However, apes’ capacity for keeping steady rhythm is very limited (Geissmann, 2000), suggesting that it constitutes a later evolutionary development in hominins. Perceptions of more detailed appreciation of rhythm, particularly of rhythmic variation, can only be hypothesized by studies of modern humans, especially of course of infantile behavior and perception.

From all this, it would seem that motor impulse, leading to rhythmic music and to dance could be at least as early as the simplest vocal inflection of sounds. Indeed, it could be earlier. We said above that animals have hearts, and certainly, all anthropoids have a heartbeat slow enough, and perceptible enough, to form some basis for rhythmic movement at a reasonable speed. Could this have been a basis for rhythmic movement such as we have just mentioned? This can only be a hypothesis, for there is no way to check it, but it does seem to me that almost all creatures seem to have an innate tendency to move together in the same rhythm when moving in groups, and this without any audible signal, so that some form of rhythmic movement may have preceded vocalization.

But Why Does Music Develop from Such Beginnings? What is the Purpose of Music?
There are four obvious purposes: dance, personal or communal entertainment, communication, and ritual.


Seemingly more important than these fairly obvious reasons for why music developed is one for why music began in the first place. This is something that Steven Mithen mentions again and again in his book, The Singing Neanderthals (Mithen, 2005): that music is not only cohesive on society but almost adhesive. Music leads to bonding, bonding between mother and child, bonding between groups who are working together or who are together for any other purpose. Work songs are a cohesive element in most pre-industrial societies, for they mean that everyone of the group moves together and thus increases the force of their work. Even today “Music while you Work” has a strong element of keeping workers happy when doing repetitive and otherwise boring work. Dancing or singing together before a hunt or warfare binds the participants into a cohesive group, and we all know how walking or marching in step helps to keep one going. It is even suggested that it was music, in causing such bonding, that created not only the family but society itself, bringing individuals together who might otherwise have led solitary lives, scattered at random over the landscape.

Thus, it may be that the whole purpose of music was cohesion, cohesion between parent and child, cohesion between father and mother, cohesion between one family and the next, and thus the creation of the whole organization of society.

Much of this above can only be theoretical—we know of much of its existence in our own time but we have no way of estimating its antiquity other than by the often-derided “evidence” of the anthropological records of isolated, pre-literate peoples. So let us now turn to the hard evidence of early musical practice, that of the surviving musical instruments.1

This can only be comparatively late in time, for it would seem to be obvious that sound makers of soft vegetal origin should have preceded those of harder materials that are more difficult to work, whereas it is only the hard materials that can survive through the millennia. Surely natural materials such as grasses, reeds, and wood preceded bone? That this is so is strongly supported by the advanced state of many early bone pipes—the makers clearly knew exactly what they were doing in making musical instruments, with years or generations of experiment behind them on the softer materials. For example, some end-blown and notch-blown flutes, the earliest undoubted ones that we have, from Geissenklösterle and Hohle Fels in Swabia, Germany, made from swan, vulture wing (radius) bones, and ivory in the earliest Aurignacian period (between 43,000 and 39,000 years BP), have their fingerholes recessed by thinning an area around the hole to ensure an airtight seal when the finger closes them. This can only be the result of long experience of flute making.

So how did tembos musical instrument begin? First a warning: with archeological material, we have what has been found; we do not have what has not been found. A site can be found and excavated, but if another site has not been found, then it will not have been excavated. Thus, absence of material does not mean that it did not exist, only that it has not been found yet. Geography is relevant too. Archeology has been a much older science in Europe than elsewhere, so that most of our evidence is European, whereas in Africa, where all species of Homo seem to have originated, site archeology is in its infancy. Also, we have much evidence of bone pipes simply because a piece of bone with a number of holes along its length is fairly obviously a probable musical instrument, whereas how can we tell whether some bone tubes without fingerholes might have been held together as panpipes? Or whether a number of pieces of bone found together might or might not have been struck together as idiophones? We shall find one complex of these later on here which certainly were instruments. And what about bullroarers, those blades of bone, with a hole or a constriction at one end for a cord, which were whirled around the player’s head to create a noise-like thunder or the bellowing of a bull, or if small and whirled faster sounded like the scream of a devil? We have many such bones, but how many were bullroarers, how many were used for some other purpose?

So how did pipes begin? Did someone hear the wind whistle over the top of a broken reed and then try to emulate that sound with his own breath? Did he or his successors eventually realize that a shorter piece of reed produced a higher pitch and a longer segment a lower one? Did he ever combine these into a group of tubes, either disjunctly, each played by a separate player, as among the Venda of South Africa and in Lithuania, or conjointly lashed together to form a panpipe for a single player? Did, over the generations, someone find that these grouped pipes could be replaced with a single tube by boring holes in it, with each hole representing the length of one of that group? All this is speculation, of course, but something like it must have happened.

Or were instruments first made to imitate cries? The idea of the hunting lure, the device to imitate an animal’s cry and so lure it within reach, is of unknown age. Or were they first made to imitate the animal in a ritual to call for the success of tomorrow’s hunt? Some cries can be imitated by the mouth; others need a tool, a short piece of cane, bits of reed or grass or bone blown across the end like a key or a pen-top. Others are made from a piece of bark held between the tongue and the lip (I have heard a credit card used in this way!). The piece of cane or bone would only produce a single sound, but the bark, or in Romania a carp scale, can produce the most beautiful music as well as being used as a hunting call. The softer materials will not have survived and with the many small segments of bone that we have, there is no way to tell whether they might have been used in this way or whether they are merely the detritus from the dining table.


This bone does raise the whole question of whether H. neanderthalensis knew of or practised music in any form. For rhythm, we can only say surely, as above—if earlier hominids could have, so could H. neanderthalensis. Could they have sung? A critical anatomical feature is the position of the larynx (Morley, 2013, 135ff); the lower the larynx in the throat the longer the vocal cords and thus the greater flexibility of pitch variation and of vowel sounds (to put it at its simplest). It would seem to have been that with H. heidelbergensis and its successors that the larynx was lower and thus that singing, as distinct from humming, could have been possible, but “seems to have been” is necessary because, as is so often, this is still the subject of controversy. However, it does seem fairly clear that H. neanderthalensis could indeed have sung. It follows, too, that while the Divje Babe “pipe” may or may not have been an instrument, others may yet be found that were ensemble musical instrument. There is evidence that the Neanderthals had at least artistic sensibilities, for there are bones with scratch marks on them that may have been some form of art, and certainly there is a number of small pierced objects, pieces of shell, animal teeth, and so forth, found in various excavations that can only have served as beads for a necklace or other ornamentation – or just possibly as rattles. There have also been found pieces of pigments of various colors, some of them showing wear marks and thus that they had been used to color something, and at least one that had been shaped into the form of a crayon, indicating that some reasonably delicate pigmentation had been desired. Burials have been found, with some small deposits of grave goods, though whether these reveal sensibilities or forms of ritual or belief, we cannot know (D’Errico et al., 2003, 19ff). There have also been found many bone awls, including some very delicate ones which, we may presume, had been used to pierce skins so that they could be sewn together. All this leads us to the conclusion that the Neanderthals had at least some artistic and other feelings, were capable of some musical practices, even if only vocal, and were clothed, rather than being the grunting, naked savages that have been assumed in the past.

Velvet is a sleek, soft fabric that is commonly used in intimate garments, upholstery and other textile applications. Due to how expensive it was to produce velvet textiles in the past, this fabric is often associated with the aristocracy. Even though most types of modern velvet are adulterated with cheap synthetic materials, this unique fabric remains one of the sleekest, softest man-made materials ever engineered.
The first recorded mention of velvet fabric is from the 14th century, and scholars of the past mostly believed that this textile was originally produced in East Asia before making its way down the Silk Road into Europe. Traditional forms of velvet were made with pure silk, which made them incredibly popular. Asian silk was already very soft, but the unique production processes used to make velvet result in a material that’s even more sumptuous and luxurious than other silk products.
Until velvet gained popularity in Europe during the Renaissance, this fabric was commonly used in the Middle East. The records of many civilizations located within the borders of in modern Iraq and Iran, for instance, indicate that velvet was a favorite fabric among the royalty the region.
When machine looms were invented, velvet production became much less expensive, and the development of synthetic fabrics that somewhat approximate the properties of silk finally brought the wonders of velvet to even the lowest rungs of society. While today’s velvet may not be as pure or exotic as the velvet of the past, it remains prized as a material for curtains, blankets, stuffed animals, and all manner of other products that are supposed to be as soft and cuddly as possible.
While various materials can be used to make velvet, the process used to produce this burnout velvet fabric is the same regardless of which base textile is used. Velvet can only be woven on a unique type of loom that spins two layers of fabric simultaneously. These fabric layers are then separated, and they are wound up on rolls.

Velvet is made with vertical yarn, and velveteen is made with horizontal yarn, but otherwise, these two textiles are made with largely the same processes. Velveteen, however, is often mixed with normal cotton yarn, which reduces its quality and changes its texture.

Silk, one of the most popular velvet materials, is made by unraveling the cocoons of silkworms and spinning these threads into yarn. Synthetic textiles such as rayon are made by rendering petrochemicals into filaments. Once one of these yarn types is woven into velvet cloth, it can be dyed or treated depending on the intended application.
The main desirable attribute of velvet is its softness, so this textile is primarily used in applications in which fabric is placed close to the skin. At the same time, velvet also has a distinctive visual allure, so it’s commonly used in home decor in applications such as curtains and throw pillows. Unlike some other interior decor items, velvet feels as good as it looks, which makes this fabric a multi-sensory home design experience.

Due to its softness, velvet is sometimes used in bedding. In particular, this fabric is commonly used in the insulative blankets that are placed between sheets and duvets. Velvet is much more prevalent in womenswear than it is in clothing for men, and it is often used to accentuate womanly curves and create stunning eveningwear. Some stiff forms of velvet are used to make hats, and this material is popular in glove linings.
China leads the world as the most prolific producer of synthetic textiles. These and other reckless industrial practices have rapidly made this communist nation the world’s largest polluter as well, and China is lagging far behind the rest of the world’s gradual switch to sustainable fabrics and non-polluting production processes.
Since “velvet” refers to a fabric weave instead of a material, it can’t technically be said that velvet as a concept has any impact on the environment. The different materials used to make velvet, however, have varying degrees of environmental impact that should be carefully considered.

Environmental impact of silk
Silk is the closest thing we have to an ideal fabric from an environmental standpoint. This embossed velvet fabric is still, in most cases, produced the same way it has been produced for thousands of years, and since the production of silk is not aided by any pesticides, fertilizers, or other toxic substances, making this fabric does not have any significant negative environmental impact.

Environmental impact of rayon and other synthetic textiles
Rayon is the most commonly used substitute for silk in velvet and velvet-inspired fabrics, and the production of this synthetic substance is significantly harmful to the environment. The rayon production process involves multiple chemical washes, and the base material of this substance is petroleum.

Essentially, rayon is non-biodegradable fossil fuel product that introduces tons of harmful chemicals into the water supply as it is created. With these detractors in full view, the only reason that rayon is still produced is that it is inexpensive.
The term “velvety” means soft, and it takes its meaning from its namesake fabric: velvet. The soft, smooth fabric epitomizes luxury, with its smooth nap and shiny appearance. Velvet has been a fixture of fashion design and home decor for years, and its high-end feel and appearance make it an ideal textile for elevated design.
Velvet is a soft, luxurious fabric that is characterized by a dense pile of evenly cut fibers that have a smooth nap. Velvet has a beautiful drape and a unique soft and shiny appearance due to the characteristics of the short pile fibers.

Velvet fabric is popular for evening wear and dresses for special occasions, as the jaguar velvet fabric was initially made from silk. Cotton, linen, wool, mohair, and synthetic fibers can also be used to make velvet, making velvet less expensive and incorporated into daily-wear clothes. Velvet is also a fixture of home decor, where it’s used as upholstery fabric, curtains, pillows, and more.
The first velvets were made from silk and, as such, were incredibly expensive and only accessible by the royal and noble classes. The material was first introduced in Baghdad, around 750 A.D., but production eventually spread to the Mediterranean and the fabric was distributed throughout Europe.

New loom technology lowered the cost of production during the Renaissance. During this period, Florence, Italy became the dominant velvet production center.
Velvet is made on a special loom known as a double cloth, which produces two pieces of velvet simultaneously. Velvet is characterized by its even pile height, which is usually less than half a centimeter.

Velvet today is usually made from synthetic and natural fibers, but it was originally made from silk. Pure silk velvet is rare today, as it’s extremely expensive. Most velvet that is marketed as silk velvet combines both silk and rayon. Synthetic velvet can be made from polyester, nylon, viscose, or rayon.
There are several different Holland velvet fabric types, as the fabric can be woven from a variety of different materials using a variety of methods.

Crushed velvet. As the name suggests, crushed velvet has a “crushed” look that is achieved by twisting the fabric while wet or by pressing the pile in different directions. The appearance is patterned and shiny, and the material has a unique texture.
Panne velvet. Panne velvet is a type of crushed velvet for which heavy pressure is applied to the material to push the pile in one direction. The same pattern can appear in knit fabrics like velour, which is usually made from polyester and is not true velvet.
Embossed velvet. Embossed velvet is a printed fabric created via a heat stamp, which is used to apply pressure to velvet, pushing down the piles to create a pattern. Embossed velvet is popular in upholstery velvet materials, which are used in home decor and design.
Ciselé. This type of patterned velvet is created by cutting some looped threads and leaving others uncut.
Plain velvet. Plain velvet is usually a cotton velvet. It is heavy with very little stretch and doesn’t have the shine that velvet made from silk or synthetic fibers has.
Stretch velvet. Stretch velvet has spandex incorporated in the weave which makes the material more flexible and stretchy.
Pile-on-pile velvet. This type of velvet has piles of varying lengths that create a pattern. Velvet upholstery fabric usually contains this type of velvet.
Velvet, velveteen, and velour are all soft, drapey fabrics, but they differ in terms of weave and composition.

Velour is a knitted fabric made from cotton and polyester that resembles velvet. It has more stretch than velvet and is great for dance and sports clothes, particularly leotards and tracksuits.
Velveteen pile is much shorter pile than velvet pile, and instead of creating the pile from the vertical warp threads, velveteens pile comes from the horizontal weft threads. Velveteen is heavier and has less shine and drape than velvet, which is softer and smoother.
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The presented paper provides a modelling strategy for roll forming of a high strength aluminum alloy tube. Roll forming allows the cost-effective production of large quantities of long profiles. Forming of high strength aluminum brings challenges like high springback and poor formability due to the low Young’s modulus, low ductility and high yield strength. Forming processes with high strength aluminum, such as the AA7075 alloy, therefore require a detailed process design. Three different forming strategies, one double radius strategy and two W-forming strategies are discussed in the paper. The paper addresses the question whether common roll forming strategies are appropriate for the challenge of roll forming of a high strength aluminum micro channel tube. For this purpose, different forming strategies are investigated numerically regarding buckling, longitudinal strain distribution and final geometry. While geometry is quite the same for all strategies, buckling and strain distribution differ with every strategy. The result of the numerical investigation is an open tube that can be welded into a closed tube in a subsequent step. Finally, roll forming experiments are conducted and compared with the numerical results.Current research in production technology focuses primarily on increasing resource efficiency and thus follows the approach of fundamental sustainability of processes and products. High strength aluminum alloys (e.g. AA7075) are commonly used in aerospace applications in spite of their high cost of about 5 €/kg and poor formability [1]. Due to ambitious legal requirements, such as the CO2 target in automotive engineering, new lightweight construction concepts are still needed [2]. An excellent basis is offered by the production of high strength AA7075 thin walled tubes as semi-finished products by roll forming. These can be further processed in subsequent customized processes such as welding, stamping, cutting or rotary swaging.

According to DIN 8586, roll forming is a bending technology with rotating tool motion to produce open and closed profiles [3]. Several pairs of forming rolls are aligned one behind the other for the forming process. The friction between the rotating forming rolls and the sheet metal causes a forward movement of the sheet. Simultaneously the sheet is formed in and between the stations. For the production of large quantities, roll forming is a cost-effective manufacturing process, compared to tube extrusion or tube drawing. Roll forming can also be competitive for smaller quantities, if the number of forming passes is small enough [4]. The incremental nature of the roll forming process also allows forming of high strength materials, such as ultra high strength steel (UHSS) [5].

During roll forming there is a limit for the amount of deformation regarding buckling limit strain (BLS), which can be reached in one forming station [6]. Abeyrathna [5], Park [7] and Bui [8] showed that longitudinal strain has a major impact on product defects, such as bow or buckling. The maximum longitudinal strain occurs in the area of the band edge. Plastic elongation in the roll gap between the forming rolls followed by compression when the sheet leaves the forming rolls leads to buckling. Figure 1 illustrates the elongation, followed by compression when forming a tube. To prevent buckling, the maximum longitudinal strain must be low. Once buckling takes place, welding of the formed tube becomes very difficult or even impossible [9]. Parameters with a large influence on buckling are the stiffness of the sheet and the yield strength of the material. According to Halmos [10], elongation of the band edge depends on the flange height and inter-station distance ld. High bending angles of a single forming station Θp and a small inter-station distance ld lead to large elongation of the band edge and thus to buckling. For circular sections (e.g. tube), the BLS is 5–10 times higher than the BLS for a U-profile [6].Groche et al. [11], Park et al. [7], Zou et al. [12] and Lee et al. [13] showed that roll forming of high strength materials and especially of high strength aluminum drawn tube brings challenges compared to commonly roll formed steel grades. High strength leads to high springback and thus to less dimensional accuracy in the processed part. Parameters, which have an influence on springback are shown in Table 1. Difficulties regarding aluminum include early fracture due to low ductility, higher springback and redundant deformation. This requires a well-designed forming strategy in order to get the lowest possible springback and buckling in the roll forming process and the best quality of the processed part. In contrast, aluminum shows a good-natured behavior with regard to buckling due to a higher value of BLS compared to steel [14].The single radius-forming strategy has the advantage to form tubes with different sheet thickness on the same tool. A flower pattern with constant bending radius over the entire cross-section of the sheet is characteristic for the single radius-forming. For high-strength materials, the single radius-forming strategy is not applicable due to high springback caused by the high elastic bending content [10, 18].

The double radius- and W-forming strategies are appropriate for high strength steels. For both strategies, two radii are combined in each pass, whereby the radius in the edge area is equal to the end radius already in the first pass of the process [18]. In contrast to double radius forming, a negative bending is initially introduced in the middle section in the W-forming process. The main advantage of this strategy is that the final radius can be formed into the band edge area at the first pass of the process [18]. Another approach is described by Jiang et al. [19] with a cage roll forming mill for the production of electric resistance welded pipes.

The height displacement of the profile is called “up-hill” or “down-hill”. During the down-hill strategy, the profile is lowered step by step in each pass. The use of a down-hill forming strategy can reduce plastic elongation in the band edge and thus the number of forming stations [10]. Based on the fundamental differences in roll forming between aluminum and steel, this publication addresses the question if one of the strategies suits for forming a tube of the high-strength aluminum alloy AA7075.

FE-Simulation of the roll forming process
The roll forming tools are designed by numerical simulation of the process. The target geometry is a tube with an outer diameter of d=54.98mm (ro=27,49mm/ri=25,99mm) and a wall thickness of s0=1.5mm. An AA7075-T6 aluminum alloy is used for the roll forming process. Table 2 shows the mechanical properties of the alloy.The first forming strategy suggested automatically by UBECO Profil after defining the target geometry is a double radius-forming strategy and has 27 passes in total. Based on tube forming sequences in literature [15, 16], the number of passes is reduced to 14 passes by skipping every second pass, in order to increase process efficiency. After the reduction to 14 passes, the edge strain is still below the critical limit in every stage of the process according to the PSA. The approach for the first forming strategy is to form the tube in uniform increments and to keep the longitudinal strain low in the band edge. The further approach is to calculate the stresses of the formed tube to arrive at the number of passes required. Forming strategy 2R is the first strategy numerically investigated by the FE-software Marc Mentat.In this paper, roll forming of a high strength extruded aluminum tube is investigated. Due to the difficult determination of the design parameters, roll forming of high strength aluminum is a challenge. Conventional roll forming strategies quickly reach their limits when forming aluminum or high strength steels. To form a tube out of high-strength aluminum alloys such as AA7075, a W-forming strategy is recommended. Another positive influence is the application of a down-hill strategy. The investigations have shown that an efficient roll forming production line for high strength aluminum tubes can be set up even with a small number of forming passes. The W-forming strategies showed a good behavior with regard to buckling, compared to the double radius forming strategy. Forming strategy W2 combines the advantages of few passes with a good final part geometry thanks to detailed process design. The numerical investigation and the following experiments demonstrated the feasibility of roll forming a high-strength aluminum tube. It is shown that conventional design methods are also valid for high-strength materials.A further result of the numerical investigation is that the design of the tools should not be based on longitudinal strain in the band edge alone. For a first estimation, the elongation of the band edge is a valid factor, but for an exact process design a numerical simulation should always be performed. In addition, BLS is material dependent, which makes an analytical calculation even more difficult.

Regarding the springback angle, the experimental investigations show little deviations from the FE-model. The reasons for this are the simplified material model, which does not consider combined hardening effects, the influence of the smaller modulus of elasticity after plastic deformation and compliance of the forming stand. Nevertheless, the simplified FE-model provides sufficiently accurate results regarding buckling and geometry of the tube.
Axial crash of thin-walled circular seamless aluminum tube is investigated in this study. These kinds of tubes usually are used in automobile and train structures to absorb the impact energy. An explicit finite element method (FEM) is used to model and analyse the behaviour. Formulation of the energy absorption and the mean crash force in the range of variables is presented using design of experiments (DOE) and response surface method (RSM). Comparison with experimental tests has been accomplished in some results for validation. Also, comparison with the analytical aspect of this problem has been done. Mean crash force has been considered as a constraint as its value is directly related to the crash severity and occupant injury. The results show that the triggering causes a decrease in the maximum force level during crash.

This work presents a model of a transformer substation with parallel connection of independent consumers via vacuum switches. Several options of an electric arc model are considered upon switching off a vacuum switch such as: KEMA model and "black box" model. Modern computer models of vacuum switches were analyzed. Since the model data were not suitable for the conditions of the experiment, a simulation computer model was developed that reflects the specifics of the operation of the substation and of the transition process upon disconnection of one or several vacuum switches. The results of the developed methodology of analyzing transition processes were verified. To check the results of computer simulation, an experimental model was constructed, it consisted of: an electric load (inductive nature), a power supply, two vacuum switches, and a measuring circuit. The circuit is switched on and off using a pneumatic system controlled by a microcontroller. The primary purpose of the work is to check mutual influence of vacuum switches upon parallel disconnection, since there may be a restrike caused by effects of switching overvoltage between neighboring switches upon irregular disconnection. The effects of a transition process in one switch on the total current of the entire system were identified. A stand for a projected trial was demonstrated as well.
With continuing development of science and technology, high voltage electrical equipment performance has been improved very fast, and dashed out some of the new switch gear, for example, the F-C circuit. Through understanding and analyzing the principle, characteristic and function, etc of F-C circuit , describes its advantages in some areas relative to the circuit breaker, For example, the protection of a more timely, overvoltage lower, functions in line with more reasonable; the lower cost for. Purpose is to allow engineers to correct reasonable selection of high voltage switch when used in the design and to promote domestic F-C circuit development.
The design, operation and use are characterized for high voltage vacuum contactors in underground coal mines endangered by methane and coal dust explosions. Design of a vacuum contactor is shown in a scheme. Vacuum contactors are superior to electromagnetic contactors. Vacuum contactors have a reduced size and weight and are characterized by improved commutation properties. Under vacuum conditions, intensity of electric discharges is lower than in an electromagnetic contactor. Reliability of vacuum contactors is 16 to 20 times higher than that of electromagnetic contactors (90% of metal vapors caused by an electric arc settle on contact surface). No time consuming buildup removal or cleaning is necessary. Optimizing contactor position in a power system in underground mines is discussed. Efficiency of using vacuum contactors and the RC systems is discussed.
Vacuum contactor is an electrically controlled switch that is used to make or break an electrical circuit with the help of vacuum interrupter, relay, and fuse. The drivers of the this market are influenced by the trends in the commercial sector and by the trends in the process and manufacturing industry. Growth in the related as well as complementary markets, such as motors, capacitors, switchgear, and transformer, also contribute towards the growth of vacuum contactors.
The global vacuum contactor market size is estimated to reach $4,814.6 Million by 2020 from $3,426.8 Million in 2015. Vacuum contactor is an electrically controlled switch that is used to make or break an electrical circuit with the help of vacuum interrupter, relay and fuse. It is mainly found in motor starters, switchgear and control gear of medium voltage fast switching devices.  The drivers of the high voltage vacuum contactormarket are influenced by the trends in the process industries, manufacturing industries, commercial and large residential sectors that use HVAC systems.

This market study covers medium voltage vacuum contactors of various voltage ratings, applications, and end-users for arriving at the global market size from 2013 to 2020. In terms of voltage rating, the vacuum contactor market is segmented into four divisions: less than 5kV, 5-10 kV, 10-15 kV and more than 15kV.

On the basis of application the vacuum contactors market is classified into six segments: motors, transformers, capacitors, reactors, resistive loads and others (such as generators, pumps, variable frequency drives, feeders, power transmitters and switchgears). Motors, transformers and capacitors are the top three applications of this industry that covers more than 65% market share.

On the basis of end-use, the vacuum contactor market is segmented into six sectors: utilities, industrial, commercial, mining, oil & gas and other medium voltage end-users. The other sector includes marine, water & waste water pumping, street lighting and transportation sector.

In terms of region, the single phase vacuum contactor is segmented on the basis of its market presence in the following regions namely North America, South America, Europe, Asia-Pacific and Middle East & Africa. These regions are further classified on the basis of top countries and their end user analyses have been made. Asia-Pacific held the largest market share owing to growth in industrialization and urbanization, followed by Europe and North America.
The global vacuum contactor market is projected to witness high growth on account of rising energy demand, growing commercial and industrial sector, and increased up-gradation of electrical infrastructure. The market was valued at $3,210 Million globally in 2014 and is projected to grow at a CAGR of 7.04% from 2015 to 2020.

The Asia-Pacific region holds a majority of market share owing to urbanization and significant development in process industries such as paper & pulp, cement, metal processing industries, and growth in manufacturing industries, followed by North America and Europe. In terms of individual countries, the U.S. and China show high growth potential. This growth can be attributed to the increasing demand for reliable power and investments for replacing aging T&D infrastructure in the U.S. and progressive economic growth of China.

Amongst the end-users, utilities sector is estimated to hold the major market share owing to increasing installation of power infrastructure. North American region is currently focussing on grid modernization and replacement of existing power infrastructure. Few countries in Europe are shifting towards renewable sources for power generation that has boosted the low voltage vacuum contactor market in the region. Vacuum contactor finds vast application in industrial and commercial sectors as well.

In terms of growth strategies, market players have mainly been forming mergers and acquisitions in order to expand as well as strengthen their market foothold. Contracts & agreements is the most commonly adopted strategy that is followed by mergers & acquisitions, and expansions. This shows a mix of both organic and inorganic growth strategies.

Leading players in the industry, based on their recent developments and other strategic industrial activities, include ABB Ltd. (Switzerland), Eaton Corporation Plc. (Ireland), Mitsubishi Electric Corporation (Japan), Schneider Electric SE (France), and Siemens AG (Germany).
With continuing development of science and technology, high voltage electrical equipment performance has been improved very fast, and dashed out some of the new switch gear, for example, the F-C circuit. Through understanding and analyzing the principle, characteristic and function, etc of F-C circuit , describes its advantages in some areas relative to the circuit breaker, For example, the protection of a more timely, overvoltage lower, functions in line with more reasonable; the lower cost for. Purpose is to allow engineers to correct reasonable selection of high voltage switch when used in the design and to promote domestic F-C circuit development.

Flight cases, carrying cases or equipment cases are sturdy, rigid trunks or enclosures designed for protecting personal goods in transit and storage. They’re typically made from plastic or metal. Many models feature a range of additional options, like heavy-duty foam inserts or additional protective padding.

High-end transit equipment cases are widely used in a range of demanding industries and roles. This includes the avionics, transport, electronic, entertainment, photography and video, test and measurement, medical, security and military sectors, to name just a few.

Flight cases are primarily designed to shield and protect fragile or high-value items during transit. Some are specifically designed to house particular pieces of equipment or instruments. Others are more adaptable and can be used to protect almost any important goods that may otherwise be at risk of damage.

Because they’re chiefly used as a handy solution for long-distance travel, long-term storage or frequent location changes, rack flight case are also commonly known as shipping cases or transportation cases. You will sometimes see them referred to as roadie cases, as they make a popular solution for conveying musical instruments and technical equipment between different locations.Flight cases can be used to store, protect and transport a wide variety of equipment types and tools, depending on which sort of case you choose. As mentioned above, musical instruments are one of the common types of flight case hardware, but you will find all sorts of items being shipped in these robust, heavy-duty enclosures.

Flight Cases for Guitars
Flight cases for guitars are a popular choice among musicians. Many such equipment or roadie cases are specially designed to provide added protection for guitars in transit. Both acoustic and electric guitars require careful handling during shipping or air travel. Their weight, size, and relative fragility mean that they are prone to damage, and this is why protection with a quality flight case during a trip is essential.

Guitar flight cases tend to be built in such a way as to provide additional support and padding around the most vulnerable parts of the instrument. These normally include both the headstock and neck of the guitar, particularly at key joints and where cutaways on the body taper sharply.

You’ll often see flight cases intended specifically for travel with guitars that include a good deal of strong secondary bracing, packing or foam padding at these vital points. They’re usually designed to provide reliable cushioning and support around the bridge and headstock of the instrument. Additional reinforcement is sometimes focused on areas where the main sections of the head, neck and body join together.

Guitar flight cases are often made from fairly lightweight but sturdy materials, such as rigid plastic or aluminium. This generally provides a good level of overall protection, while also being more convenient to carry between locations. Cases designed for shipping multiple guitars together often include built-in racking systems. These typically come with wheels for easier manoeuvring on the ground.

Flight Cases for Guitar Amps
Just as with guitars themselves, flight cases for guitar amps are another important piece of kit for many travelling musicians and road crews.

A guitar amp flight case can come in many sizes and configurations, depending on the type and size of amp or speaker you need to pack up safely ready for shipping. Again, they tend to focus on delivering robust knock and fall protection, with heavy padding on the interior.

Like many such equipment cases, they’re often made from high-grade plastic or metals like cast aluminium. Their bodies may be ribbed for further strength and rigidity, offering an ideal combination of strength and a lighter carry weight for travel.

Additional features can include:

Sturdy comfort grip handles with increased lift capacities

Retaining straps

Toggle catches with wire seals and padlock facilities

Rubber seals for better waterproofing

Stacking locators in the lid, to help when you need to pack or store more than one crate together

Flight Cases for Drums
Flight cases for drums are also a popular choice as proper storage and transportation of drumkits is equally important. It’s particularly vital to protect drum kits in transit as their large size and hollow construction can leave them extremely vulnerable to damage if they are not properly protected.

The best drum and cymbal flight case options generally tend to include many similar features to guitar and amp lighting&speaker flight case. Look out for benefits such as watertight, airtight and crushproof certifications. These offer reassurance that the case will guard against damage from knocks or falls, water, humidity, and prolonged exposure to heat.

Additionally, some models may even offer functions such as an automatic pressure purge valve. This helps to ensure the shifting forces acting on delicate instruments during air travel remain balanced within safe limits.

Production Flight Cases
Production flight cases and equipment containers also include a wide range of products suitable for shipping important and valuable tech between locations. Common examples include mixer flight cases or sound desk flight cases.

As with all such items, you’ll usually want to look for a robust plastic or aluminium model. Rugged body reinforcement and a good amount of interior shock proofing provided by thick foam inserts are also important.

When buying flight cases for mixers, it’s vital to look out for designs offering features that directly benefit electronics in transit. Waterproof models are particularly popular for shipping mixers, PAs and other production equipment. Shop for cases with sturdier rubber seals and secure fastening/locking systems, helping to guard delicate electronics from humidity, moisture, dust and debris.

Padlock compatibility is another common feature for production flight cases. This makes the cases more secure and helps to prevent unauthorised access to the contents.

Different Flight Case Types
Flight Case Racks
A flight case rack can be extremely important when shipping multiple items together in the same crate or equipment box. Case racks may be integrated into some designs, often called rackmount flight cases. Alternatively, racks can be purchased as an additional accessory designed to fit inside an existing transit case.

Plastic or metal equipment containers featuring two or more racks are available for both larger and smaller items. These can include various types of electronic equipment, organised spaces for securing different tools, or any other fragile items that need to remain protected and separated during travel.

Quality rackmount flight cases often feature benefits such as panel-mounting capabilities for creating more robust compartments, with shock-mounted rack sleeving and suspension systems for added impact guard.

They make an ideal solution when used as a server flight case, as they’ll often allow for multiple units to be organised and shipped together. This helps you to keep track of exactly which components should be kept together. It also makes reassembly of servers and other computing or electronics arrays much easier when you reach your destination.

Lightweight Flight Cases
Since the items being stored and transported in equipment cases tend to be too large or heavy to carry easily outside of a case, the last thing you want is for the container itself to add a huge amount of bulk to the overall package.

Many of the best lightweight flight case options tend to be made from sturdy plastic or cast aluminium. These materials offer an ideal balance of strength, rigidity and durability while being easy to pick up and move around.

You may also be surprised at the manoeuvrability of some of the larger light flight cases. These also tend to be easily stackable when not in use. Some models even feature stacking locators embedded into their secure-latching lids to make the job even more straightforward.

Hard Carry Cases
Transporting delicate items like laptops or test equipment is an increasingly common necessity. In situations like this, hard carry cases are often chosen for travel with smaller individual pieces of technology or electronics equipment.

Equipment carrying cases are designed to hit the ideal middle ground between portability and protection. This type of hard carrying case tends to be constructed from lighter materials, with prominent easy-grip handles. They also commonly feature a range of additional locking, latching and security measures.

Useful features on cases in this category tend to include IP-rated rubber seals for all-round moisture and dirt protection, and various types of secure latching or locking systems. Whether you opt for a metal or plastic hard carrying case, other handy benefits might include:

Sturdy plug-in lid hinges

Stable and robust case feet

Ergonomic handle designs

High-grade foam inserts for enhanced impact protection Lcd tv flight case with wheels and castors are a popular choice due to their accessibility and ease of movement. Equipment cases with wheels tend to come in several different variants. Firstly, storage boxes with wheels added as an additional convenience tend to have smaller and potentially less sturdy castors and bearings. These are often recessed further into the body of the case, allowing for easier stacking. These models may be less suitable for wheeling over longer distances.

On the other hand, transport cases which feature more prominent wheels often cite full manoeuvrability as a key part of their overall design. This becomes increasingly important with large, heavy or bulky items.

Such models will frequently list features like heavy-duty wheels made from strong materials like polyurethane. Bearings will often be steel or reinforced with other rugged materials and may be self-oiling for smoother free-running action over a wider variety of terrains and surfaces.In addition to protecting against unwanted moisture, waterproof equipment cases also offer a fairly robust level of protection from dust and dirt ingress. When you’re looking for a waterproof hard case, paying attention to the all-important IP rating is key to finding the exact product you need for a particular job or environment. For assistance with this, you can read our comprehensive guide to IP ratings.

Once again, waterproof hard cases can be made from materials such as aluminium and plastic. Certain options are also graded for protection against chemicals, as well as against general environmental hazards such as humidity, rain, spillages and dust.

Regardless of the material you choose, among the most important things to look out for will be thick rubber seals or O-rings around openings, hinges and latches. These will allow you to maintain a watertight (and sometimes completely airtight) interior to your equipment case, even under varying pressures at different altitudes.

Similarly, some models also include automatic one-way pressure release valves. Again, this will help to keep conditions inside the trunk balanced within safe limits at all times.Small flight cases tend to be designed around both portability and protection. This means that they are normally focused on convenience and comfort during journeys, as well as being built sturdily enough to withstand various types of impact, damage or ingress.

Small carrying cases made from aluminium or rigid plastic will also commonly feature some arrangement of foam inserts or padding. This is ideal for protecting less bulky items such as electronics and tools, as well as preventing the contents from moving around too much in transit, and potentially sustaining damage from knocking against the interior of the case.

These smaller cases are less commonly found with wheels attached, as their size usually does not warrant this addition. However, they will often include sturdy feet and a full range of security measures such as latches, locks and wrist straps.Plastic flight cases are a highly popular option. This is due to the impressive combination of ruggedness and low weight offered by modern plastics and polymers. Many of the leading plastic carry cases in the UK and beyond are virtually indestructible under normal transport conditions. Plastic equipment cases offer robust protection against both knocks and impacts, as well as bringing a certain level of water and chemical resistance.

As with all flight case types, plastic equipment boxes can be bought in a wide range of configurations. Advanced IP ratings offer full guarding against moisture, humidity, dust and dirt. Many such products with higher levels of ingress protection will feature thick rubber seals and double-step latching, delivering an extremely reliable performance when closed and secured.Among the most common types of modern metal flight cases are aluminium flight cases with foam inserts. These, alongside other metal flight cases, can be found in widespread use across a huge range of industries and sectors.

Metal Equipment&tool Flight Case are available in both large and small sizes and offer a perfect solution for transporting a huge variety of delicate or high-value goods safely across long distances. Common uses include shipping fragile electronics, instruments and tools.

Lockable metal flight cases with foam padding are highly robust, often featuring reinforced or ribbed cast aluminium side and top panels for added strength. Hinged lids and secure latching mechanisms are frequently coupled with ergonomic comfort grip handles. Wheels or castors tend to be extremely sturdy and smooth-running.

You may notice that many models and types of aluminium flight case are also designed with corners made from toughened, impact-resistant plastic. Not only does this provide extra protection during travel, but it also allows for easier stacking, so you can reduce the amount of storage space needed.

As with all flight cases, metal versions typically include removable PE foam inserts around the walls, base and lid for advanced protection against damage.

Aeroacoustic performance of fans is essential due to their widespread application. Therefore, the original aim of this paper is to evaluate the generated noise owing to different geometric parameters. In current study, effect of five geometric parameters was investigated on well performance of a Bladeless fan. Airflow through this fan was analyzed simulating a Bladeless fan within a 2 m×2 m×4 m room. Analysis of the flow field inside the fan and evaluating its performance were obtained by solving conservations of mass and momentum equations for aerodynamic investigations and FW-H noise equations for aeroacoustic analysis. In order to design table bladeless fan Eppler 473 airfoil profile was used as the cross section of this fan. Five distinct parameters, namely height of cross section of the fan, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter and aspect ratio for circular and quadratic cross sections were considered. Validating acoustic code results, we compared numerical solution of FW-H noise equations for NACA0012 with experimental results. FW-H model was selected to predict the noise generated by the Bladeless fan as the numerical results indicated a good agreement with experimental ones for NACA0012. To validate 3-D numerical results, the experimental results of a round jet showed good agreement with those simulation data. In order to indicate the effect of each mentioned parameter on the fan performance, SPL and OASPL diagrams were illustrated.
Nowadays, the axial and radial fans are employed for various applications, such as cooling systems, air conditioning, ventilation of underground spaces, etc. The aeroacoustic performance of fans have been improved by increasing advancements in the computational fluid dynamics (CFD) and economic growth, then different types of fans with various applications and higher efficiency is offered. In 2009, a new fan was invented that its appearance and performance was different from conventional fans. The main differences of this fan with respect to conventional fans (axial and radial fans) are the multiplying intake air flow and lack of observable impeller [1]. This fan namely Bladeless/Air Multiplier fan was named on the basis of the two mentioned features. Until now, this fan is manufactured for domestic applications by diameter of 30 cm.

There are two typical fans widely used: axial and radial types, however Bladeless fans are completely distinct from those fans in mechanism aspect. Bladeless fan is similar to centrifugal fans in terms of radial impellers for intake air and also it is similar to axial fans in terms of preparing higher rate of outlet airflow. Although studies about wall and table bladeless fan are rare in the literature, numerous experimental and numerical studies have been performed on the axial and centrifugal fans. Lin, et al [2], designed a Forward–Curved (FC) centrifugal fan by numerical simulation and experimental tests. They selected NACA 0012 airfoil profile for its blade and indicated that this fan produces a higher maximum flow rate and static efficiency when the blade inlet angle is 16.5º. The influence of enlarged impeller on performance of a centrifugal fan was experimentally examined by Chunxi, et al [3]. By comparison of obtained results, they observed that flow rate, total pressure rise, shaft power and sound pressure level increased while the efficiency of fan decreased for larger blades. Govardhan, et al [4], investigated the flow field in a cross flow fan by three-dimensional simulation via the commercial software code, CFX. They simulated three impeller geometries for different radius ratio and blade angles, and then they compared their efficiency with each other. Sarraf, et al [5], experimentally studied axial fans performance for two identical fans but with different impeller thickness. They indicated that the overall performance of these two fans is same, but the fan with thicker blades contained higher rate of pressure loss by the means of 8%. Also the efficiency of the fan with thinner blades was 3% higher than the fan with thicker blade. Mohaideen [6] improved an axial fan blade by using the finite element method (FEM) and reduced 18.5% of the blade weight after optimizing on the blade thickness via stress analysis by ANSYS commercial software.

There are a lot of studies on the generated noise by various airfoils that is carried out by experimental and/or numerical approaches. Chong, et al [7], measured the generated noise by a 2-D NACA 0012 airfoil at the angles of attack 0º, 1.4º and 4.2º, in a wind tunnel. They performed their experiments for some Reynolds numbers between 1×105 and 6×105. The experimental results indicated that the pressure gradient was raised on the airfoil pressure surface by increasing of attack angle, so the noise can be produced by this phenomenon. Devenport, et al [8], carried out experimental tests on the noise propagation of NACA 0012, NACA 0015 and S831 airfoil. The obtained results indicated that the airfoils with more thickness made lower noise and revealed the different angles of attack had little influence on the sound production for NACA 0012 and NACA 0015 airfoil. Casper, et al [9], solved the equations of FW-H and developed new equations. They computed the produced noise by a NACA 0012 airfoil in a low Mach number flow. The analytical results and experimental data for NACA 0012 airfoil were in good agreement.

So far, many experimental and numerical studies have been performed on the generated sound by axial and centrifugal fans. Many researchers have used the FW-H equations to predict the sound radiation of fan by numerical simulation. Ballesteros-Tajadura, et al [10], measured the noise of a centrifugal fan via FW-H noise model using the CFD code, FLUENT. By comparing numerical and experimental noise results, they showed the FW-H model was able to predict the tonal noise with reasonable accuracy. Solving FW-H equations, Moon, et al [11] and Cho, et al [12] calculated the amount of radiated sound from an axial fan and a cross flow fan, respectively. Younsi, et al [13], used numerical simulation to predict the noise level in a HVAC forward centrifugal fan. By comparing numerical and experimental data, they showed the good agreement between simulation and the experimental data. In some papers, researchers have studied the source of generating noise in different fans by using the computational aeroacoustics (CAA) [14]. Khelladi, et al [15], calculated the noise of a high rotational speed centrifugal fan via FW-H analogy and solving the Reynolds Averaged Navier-Stokes (RANS) equations. They compared the numerical and experimental data and also evaluated the aerodynamic performance of fan. In 2009, Sorguven, et al [16], studied aerodynamic and aeroacoustic performance of two radial fans. Moreover in their study, LES turbulence modeling and FW-H noise modeling were employed. They showed a satisfied agreement of experimental and numerical results and reported FW-H model as a reasonable model for evaluating aeroacoustic performance of fans.

Although Bladeless fan is invented in 2009, but until now aeroacoustic performance of this fan has not been studied numerically or experimentally for different conditions. This fan is designed for home applications by diameter of 30 cm and the only available geometric information is mentioned in patent documentation [1]. In the present study, the effect of five geometric parameters is investigated on performance of a Bladeless fan by diameter 30 cm. The studied parameters are height of fan cross section, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter and aspect ratio for circular and quadratic cross sections. The unsteady conservation of mass and momentum equations are solved to simulate three-dimensional incompressible flow in the Bladeless fan. The Ffowcs Williams and Hawkings (FW-H) formulation is solved to calculate the noise propagation of smart bladeless fan. Firstly, the generated noise of a NACA 0012 airfoil is computed to validate aeroacoustic results by experimental data [17]. The obtained numerical results and the experimental data are in the reasonable agreement, so the FW-H model is employed to measure the tonal noise of Bladeless fan. To validate 3-D numerical simulations, the experimental results of a round jet [18] are compared with numerical simulation results. Since there is not any experimental data about Bladeless fans, round jet is selected due to much similarity. The turbulence in the Bladeless fan is simulated by standard k−ε turbulence model. In order to design cross section of Bladeless fan, Eppler 473 airfoil is chosen among standard airfoils. Eppler 473 airfoil is selected because it is an appropriate airfoil for low Reynolds numbers and high similarity of this airfoil profile to original cross section (designed by inventor) [1]. The volume flow rate is calculated at a distance up to 3 times of nozzle diameter in front of the fan (around 1000 mm) [1]. The numerical results for Bladeless fan show that the investigated parameters in this study are very important to improve the fan performance. Thus these parameters should be considered to design a high performance Bladeless fan.

Mechanism of Bladeless Fan
This fan is produced for domestic applications and its diameter is 30 cm. The mechanism of inlet and outlet airflow from this fan is shown in Fig. 1. At the first stage, the airflow is sucked into the fan through a rotating DC brushless motor and a mixed flow impeller. The intake air is accelerated by passing through an annular aperture which the cross section of this fan is similar to an airfoil profile. Then air is pushed out from a ring shape region, so the air velocity is increased in this region. A considerable pressure difference is generated between both sides of the fan and the discharged air can be described by Bernoulli’s principle. This pressure difference draws the behind and surrounding air toward front of fan. Therefore, a smart tower bladeless fan amplifies the intake air by drawing the air behind and around the fan. Thereby the inventor of this fan claims that [1] this fan multiplies intake air at about 15 times at distance 3D front of fan (around 1000-1200 mm) [1, 19]. All of described stages are shown in Fig.

Manufacturing and development of a bolted GFRP flange joint for oil and gas applications
The manufacturing industry saw a significant rebound, and oil prices started to recover as well. Both of these trends are expected to continue in 2017.

At Allied Valve, we also saw some big changes this year. We expanded our product line to include Masoneilan control valves, CDC rupture discs, and Groth relief valves and flame arresters. We also beefed up our service capabilities with a new Mobile Lab trailer and new control valve testing systems.

Finally, we continued our initiative to bring you valuable content related to valves, actuators, and the many industries we serve. Here are our top 5 industrial valve articles of 2016.

Maximizing Your Control Valve Performance: A Guide to Control Valve Selection, Maintenance, and Repair
Process plants can contain thousands of control valves, responsible for keeping process variables like flow, level, pressure, and temperature within the desired operating range. Despite their importance to product quality, efficiency, and a company’s bottom line, control valves are often neglected. This article provides an in-depth look at the factors that affect control valve performance and how to keep your valves always working their best.
It came to our attention earlier this year that some safety valves containing Thermodiscs (e.g., Consolidated 1811 and Consolidated 1711 series) were being put through hydrostatic testing. These valve parts are designed for steam service only and water can cause damage, potentially beyond repair. This article describes the problems that hydrostatic testing can cause and what you can do to mitigate these problems.
The American National Standards Institute (ANSI) and the International Society of Automation (ISA) provide standards for the hydrostatic testing of control valves. The goal of the test is to verify the valves’ structural integrity and leak tightness. This article summarizes the fluid, pressure, and time requirements of hydrostatic testing as well as the standards for acceptable performance.
To work properly when they’re needed, all valves must be maintained. It used to be that preventative maintenance was the only option. But with the diagnostic tools available today, it’s possible in some cases to use a data-based predictive approach instead. Both of these approaches are part of an effective valve disc maintenance program. This article helps you understand when each of them is most appropriate.
Sand casting can be used for the majority of metals. Even highly reactive magnesium is sand cast provided care is taken and the correct materials used by adding what are called inhibitors into the sand.

Sand castings inevitably have a slow cooling rate because of the large insulating mass of sand surrounding the liquid metal as it cools. Grain sizes and dendrite arm spacings tend to be larger than in equivalent section sizes in die-castings.
Sand casting involves the pouring of molten metal into a cavity-shaped sand mould where it solidifies (Fig. 6.8). The mould is made of sand particles held together with an inorganic binding agent. After the metal has cooled to room temperature, the sand mould is broken open to remove the casting. The main advantage of sand casting is the low cost of the mould, which is a large expense with permanent mould casting methods. The process is suitable for low-volume production of castings with intricate shapes, although it does not permit close tolerances and the mechanical properties of the casting are relatively low owing to the coarse grain structure as a result of slow cooling rate.
The goal of this experimental study is to manufacture a bolted GFRP forged flange connection for composite pipes with high strength and performance. A mould was designed and manufactured, which ensures the quality of the composite materials and controls its surface grade. Based on the ASME Boiler and Pressure Vessel Code, Section X, this GFRP flange was fabricated using biaxial glass fibre braid and polyester resin in a vacuum infusion process. In addition, many experiments were carried out using another mould made of glass to solve process-related issues. Moreover, an investigation was conducted to compare the drilling of the GFRP flange using two types of tools; an Erbauer diamond tile drill bit and a Brad & Spur K10 drill. Six GFRP flanges were manufactured to reach the final product with acceptable quality and performance. The flange was adhesively bonded to a composite pipe after chamfering the end of the pipe. Another type of commercially-available composite flange was used to close the other end of the pipe. Finally, blind flanges were used to close both ends, making the pressure vessel that will be tested under the range of the bolt load and internal pressure.
In manufacturing of the steel bridge, fillet welded T-joint is widely used and angular distortion is often generated. So, reduction or control of angular distortion without additional processes to welding is strongly demanded because it takes great time and effort to correct the angular distortion. In this study, the effectiveness of welding with trailing reverse-side flame line heating for preventing angular distortion was investigated through the welding experiment and numerical simulation in submerged arc welding of fillet T-joint with three different thick flange plate. First, the heat source models for numerical analysis of both submerged arc welding and flame line heating were constructed based on the comparison with the measured temperature histories and angular distortion. And then, these heat source models were used in combination with various kinds of distance between two heat sources to make clear the appropriate distance condition for smallest angular distortion was 150 mm, and it does not depend on thickness of flange plate. It was also confirmed that the experimental angular distortions were in good agreement with those calculated. With a focus on the influence of thickness of flange plate, the reduction of angular distortion by welding with trailing reverse-side flame line heating becomes smaller with increasing thickness of flange plate. However, angular distortion could be adequately prevented under the appropriate flame line heating condition in either thickness of flange plate because the welding-induced angular distortion also becomes smaller with increasing thickness of flange plate. Thus, it was concluded that welding with trailing reverse-side flame line heating could be useful for preventing angular distortion of fillet T-joint, which is a component of steel bridge, enough not to correct it after welding.
Garlock offers a range of Butterfly Valves for different applications. Ranging from GAR-SEAL Butterfly Valves are used extensively where corrosive, abrasive and toxic media, to STERILE-SEAL valves are used in applications where sterile processes need to be maintained in the pharmaceutical and food industries.
Depending on your application, different air valve material and design type should be used. For a better understanding on which type of Garlock Butterfly Valve will best fit the application, you can refer to our Chart
The mechanism of opening of the aortic valve was investigated in dogs by attaching radiopaque markers to the commissures and the leaflets. Analysis of abnormal cardiac cycles demonstrated that, when the ventricular pressure first equalled the aortic pressure, the intercommissural distances increased 9 percent, and the valve opened with a stellate orifice without forward flow and without a rise in aortic pressure. Further opening of the aortic valve was dependent on forward flow over a narrow range. A new mechanism of aortic valve opening is proposed. This mechanism results in minimal flexion stresses on the leaflets and is important for the longevity of the normal aortic valve. It can occur only if the leaflets arise from an expansile aortic root.
Original LESER spare parts are the guarantee that also after maintenance works your safety valve precisely fulfills its task to protect people and environment. Learn with the spare pare finder which subassemblies are installed in your individual safety valve to be able to order the correct LESER spare part. The spare part finder shows the bill of materials of your individually configured valve body.
The list shown contains all components, regardless whether they are needed as spare parts. As initial spare parts supply for API, High Efficiency, High Performance, Compact Performance and Modulate Action safety relief valves, we recommend the Spare Part Kits. For the other product groups please contact us for an inital spare part offer. Find out more about LESER-Spare Parts Kits.
Please enter a combination of a serial number (SerNr.) and an article number (ArtNr.) to bring up the right spare parts (e.g. SerNr: 10202021, ArtNr: 4411.4443). You can find the serial and article numbers on the name plate of the valve or on the Certificate for Gobal Application, which you can download in the CERTIFICATES-area.
Please pay attention to the following user instruction:
The spare part finder currently only shows bills of materials for valves assembled in our Hohenwestedt plant. For spare parts lists of other valves, please contact your local partner.
Some items in the bill of materials are subassemblies which contain one or several of the following items. In most cases the subassembly should be ordered as a spare part.