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Effects of melting parameters and quartz purity on silica glass crucible produced by arc method We have investigated the effect of hydroxyl (OH) content in fused silica crucible on the scintillation and optical properties of the CsI single crystal, but not limited to, grown by Bridgman technique. For the purpose, 0.1 mol% Tl doped CsI single crystals were grown in crucibles made from fused silica of different grades with OH content varying from 20 ppm to 200 ppm. Silica glass of crucibles was characterized by FTIR and UV–VIS-NIR spectroscopy for the estimation of OH content. Grown crystals were tested for their scintillation performance and a correlation between OH content in silica glass and crystal quality is established. The possibility of ‘OH’ out-diffusion from silica crucible into the melt at higher temperature was further established by temperature dependent study of outgassing from silica crucible by residual gas analyzer (RGA). Further, an optimized process for silica crucible annealing to remove OH (<20 ppm) is proposed to achieve excellent crystal quality of a 5.6% energy resolution at 662 keV without any co-doping in Tl doped CsI. In photovoltaic industry, silica crucible has an important influence on the quality of single crystal silicon. To obtain a silica glass crucible with large diameter, high uniformity, and low bubble content, two series of crucibles were prepared by the arc melting method, one with various melting parameters (initial power, melting power, and melting time) and crucible sizes, and the other with various high purity quartz crucible. The bubbles inside the crucible wall and pores on the inner surface were all measured using a polarised optical microscope and a portable microscope. The results show that all crucibles have a bubble aggregation area in their inner surface (0–0.4 mm), in which the density and size of bubbles are affected by melting time, melting power, and the distance between the crucible and the graphite electrode. The uniformity of the crucible decreases as the crucible diameter increases (16–28 inches), and the crucible is relatively stable when the initial power is below 400 kW. In final, a silica crucible with large size (diameter of 28 inches) and low bubble content on inner surface (∼50% reduction than that of traditional crucibles) was successfully prepared, which is of great value to the photovoltaic industry. Currently, the primary materials for fabrication of solar cells are polycrystalline silicon and monocrystalline silicon, with a market share greater than 85% [1]. Solar cells with higher efficiency can be fabricated from monocrystalline silicon, which is usually obtained using the Czochralski (Cz) method [2, 3]. The silica crucibles used in the Cz method are typically made from high-purity amorphous silica. In general, these crucibles consist of two different layers: a transparent layer (Almost bubble free) and a bubble-containing layer (BC layer) [4]. In the outer BC layer, the material contains many bubbles, which decrease transparency. The composition of the gas inside the bubbles remains a matter of debate. It is most likely air, perhaps containing traces of carbon, or water vapour [5]. The inner transparent layer is almost completely transparent, and because this layer is in direct contact with the silicon melt, it is important to keep it free from bubbles throughout the Cz process to ensure that fewer bubbles are released into the melt and subsequently into the silicon ingot. The silica crucible, which is in direct contact with liquid silicon, has an important impact on the quality of monocrystalline silicon, and silicon wafers with pinholes or dislocations cannot be used for solar-cell fabrication [6]. The industry has therefore devoted extensive efforts to preventing bubbles from entering the melt during the phase of crystal growth [4]. The high-purity quartz sand used to prepare glass crucibles contains various amounts of mineral inclusions (mica, feldspar, etc) and fluid inclusions [7, 8], which can form bubbles at high temperatures. In addition, other gases can affect the quality of monocrystalline silicon. Gas bubbles of SiO and CO can be produced in the melt–crucible interface [9, 10], forming small gas bubbles in the crystal or leading to the generation of dislocations inside the crystal [11]. Argon may also enter the silicon ingot as a protective gas [12]. Reducing the release of bubbles from the transparent layer into the melt during the Cz process can reduce the number of defects in the structure of monocrystalline silicon [13]. In fact, many experiments have been carried out to improve the properties of polycrystalline silicon by improving the purity of fused silica crucibles, but few studies have been reported in the field of single-crystal silicon [14–16]. Therefore, one of the purposes of this experiment is to reduce the bubble content in the transparent layer of crucibles by reducing the impurity element content of quartz.
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Solar street lighting is a unique opportunity for sustainable recovery In response to the economic fallout from COVID-19, the European Union has formulated a major recovery plan for the continent with a key focus on adapting to the digital age and investing in cleaner and more resilient technologies for the future. In the U.S., the 2021 American Jobs Plan aims to steer $2 trillion into productivity and long-term growth, including a strong focus on building resilient and climate-friendly infrastructure. With economic and climate resilience plans taking a more concrete shape across the globe, Signify believes that solutions such as solar lighting pave the way for countries to build back better. According to Allied Market Research the global market solar energy was $52.5 billion in 2018 and is set to grow to $223.3 billion by 2026, vastly accelerating the scale of renewables. One of the fastest growing solar street light. "Solar street lighting technology has come on leaps and bounds in recent years and is fully aligned with the goals of EU and U.S clean energy and economic stimulus initiatives. Just 15 streetlights can save enough electricity to power a home for a year," said Harry Verhaar, global head of government and public affairs at Signify. "Being a digital technology, it can be connected to sensors and be controlled remotely, enabling forward-thinking municipalities to leapfrog to solar and reap the benefits of the digital age." President Joe Biden’s administration already has proposed $621 billion of additional investment in transportation infrastructure, with $20 billion earmarked to improve road safety and $174 billion for electric vehicles. A sizeable chunk of the latter would be spent on grant and incentive programs to build a national network of 500,000 electric vehicle charging stations by 2030. Signify advocates specifically for the wide adoption of solar and all in one solar street light which will not only help improve road safety, but also pave the way to lower emissions and eliminate the need for extra power stations to power the street lamps. This is particularly useful in more remote areas where existing infrastructure is minimal. With the strain taken off power stations, excess capacity could be diverted towards supporting charging stations for electric vehicles. Greek experience Solar is the ideal technology for serving far-flung communities with intermittent power supply or coverage. For example, in 2020, Signify installed solar streetlights on the Greek island of Leipsoi in areas lacking full electricity coverage including a playground, allowing the community to feel safer. A total of 28 autonomous Philips SunStay luminaires were used, each combining a solar panel, an LED light, a charge controller and a battery in one housing unit. The lights also contained an infrared motion sensor which detects movement and alters brightness accordingly, increasing energy efficiency and minimizing light pollution. "As we have many hours of sunshine throughout the year this is a very effective and functional solution for those areas on our island that are not connected to the power grid," said Fotis Mangos, mayor of Leipsoi. "The lights have such an aesthetic design that they seamlessly blend in with our island’s natural landscape."
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On the Move: Unpacking the Challenges and Opportunities of Electric Vehicles SINGAPORE - More than 600 electric vehicle (EV) chargers will be installed at some 200 public carparks in HDB estates, industrial estates and the Central Business District over the next 12 months. The first of these car chargers are expected to be installed by the end of this year. By the third quarter of next year, there will be 210 charging points in the central region, 50 in the north, 100 in the north-east, 120 in the east and 140 in the west. The Urban Redevelopment Authority (URA) and the Land Transport Authority (LTA) said on Friday (Sept 3) that a consortium comprising ComfortDelGro Engineering and Engie South East Asia has been awarded a tender to set up EV charging points in selected carparks in the central, east and west regions. Another consortium comprising Primech A&P, Charge+, Sunseap Group and Oyika has been awarded a tender to install the charging infrastructure in carparks in the north and north-east regions. The tenders, which form a pilot tender put out in November last year, are the first steps towards a national target of 40,000 charging points in public carparks by 2030. URA and LTA said they wanted to ensure that the pilot tender for the charging points was awarded to operators with quality charging services, financially sustainable business models and competitive charging prices. "As such, agencies adopted a price-quality method to assess and select proposals that would provide the best value for both consumers and the authorities," said URA and LTA. They said the consortiums led by ComfortDelGro and Primech A&P have offered competitive charging rates and a sustainable business model. URA and LTA added that these two consortiums have also committed to delivering a complete suite of services, including the installation, operation and maintenance of EV charging infrastructure, among other proposals. They said the consortium will pay the Government concession fees ranging between $0.108/kWh and $0.154/kWh for the right to deploy charging points. ComfortDelGro and Engie said in a joint statement on Friday that they won the tender to install 479 of the 632 metal car charger in the pilot roll-out. They said the chargers installed by them will comprise 192 22kW AC chargers, 279 7kW AC chargers and 8 50kW DC chargers.
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Rising Prices for PE, PVC; Others Flat to Down The trajectory of prices of the five volume commodity PVC resin powder was upward through September; but starting last month, a reversal was underway for most of these resins, possibly excepting PE and PVC. Factors in the continued flat-to-downward trajectory for PP, PS and PET included expectations of improved supply availability, lower feedstock prices, slowed seasonal demand, and loss of export opportunities due to higher prices. Factors maintaining strong pricing for PE and PVC, at least in the short term, included strong demand and tight monomer and polymer supplies brought on by planned and unplanned production shutdowns. These are the views of purchasing consultants from calcium carbide method pvc resin, Inc. (RTi), senior editors from PetroChemWire (PCW), and CEO Michael Greenberg of The Plastics Exchange. Polyethylene prices moved up 5¢/lb in September, capping the fourth consecutive month of price hikes, bringing the total to an unprecedented 19¢/lb. Suppliers also came out with a fifth increase—another 5¢/lb—for October, owing primarily to continued strong demand and tight supplies, made tighter following precautionary shutdowns for Hurricane Laura in late August. Mike Burns, RTi’s v.p. of PE markets, held that PE prices would stay firm, with the October hike—if not implemented right away—hanging over discussions with customers for the remainder of the year, due to sustained demand and tight inventories. PCW’s senior editor David Barry said he would not be surprised if suppliers stuck to their increases, but expected processors would have better leverage this month and in December in the negotiation of 2021 contracts. With the exception of HDPE blow molding grades, where a real shortage occurred, processors were able to get what they needed, but went through it faster than anticipated, noted Burns. PE Price Trends November 2020 Both Burns and Barry ventured that a slow recovery of tight suspension method pvc resin inventories was already underway at the start of the fourth quarter, which ought to help ease price pressure in first quarter of 2021. Going into October, The Plastic Exchange’s Greenberg reported that while demand for spot PE had been good, processors generally opted for just single truckloads, and a whisper of uncertainty had crept into the market. “The fourth quarter often brings softer demand and could provide the market an opportunity to rebalance especially when downed plants return fully online and new reactors begin production,” he commented. PP Prices Up, Then Flat to Down Polypropylene prices moved up 3¢/lb in September, despite stability in propylene monomer contract prices, which remained at August’s 36¢/lb level. Moreover, PP suppliers announced another 3¢/lb “profit-margin increase” for October, a move that looked to be at least partially successful due to tight supply and some rebound in domestic demand, according to Scott Newell, RTi’s v.p. of PP markets, as well as PCW’s Barry, and The Plastic Exchange’s Greenberg. All three saw the recent upward trajectory halting, if not reversing. Newell ventured that suppliers’ attempted margin expansions in September and October would erode between mid-month and December. “Suppliers have had leverage all this time owing to unplanned and planned monomer and PP outages, and low capacity utilization overall (around 83%). But the longer buyers can wait to order for 2021, the better. I expect quite a few pounds of PP and monomer capacity to be brought on stream in that time frame.” PCW’s Barry reported that while suppliers were seeking to boost their margins further in October, there were already signs that high PP prices were crimping demand for price-sensitive products such as PP tubs and totes, which depend heavily on “big-box” retail channels. He cited factors such as slower demand, rising PP imports and improving operating rates in the fourth quarter that could bring a turnabout in the PP supply situation in late November into December.
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A review of a machine design of chocolate extrusion based co-rotating twin screw extruder Based on innovation and competitive market for food industry, there are several food products which have been designed to attract customer. Since there is USD 39,431 millions of chocolate sales in 2018, USA [1], chocolate product shapes have been developed based on manufacturing process. This paper presents a review process of a cocoa machine design of chocolate extrusion based co-rotating twin screw extruder. A property of suitable chocolate for extruder was established. The pros and cons of machine extruder for food processing including, a screw extruder design were exposed. Since there were problems in the chocolate extruder, the process parameters such as barrel temperatures, feed rate, screw speed, motor load and melt pressure were established. These parameters would be applied to design screw extruder for chocolate processing. Demand is growing for higher-quality chocolate, alongside more sustainable manufacturing processes. But current chocolate production faces problems keeping up. The different production stages rely on their own specific cocoa equipment, components can be difficult to clean and potentially harmful metal particles can be released into finished products. EU support helped the BAT project optimise the chocolate manufacturing process with a versatile ‘one-stop shop’ machine which, as well as being easy to clean, avoids the need for producers to run a set of expensive, bulky and energy-intensive machines. The new refining technology There are typically around seven stages to chocolate manufacturing involving three to five dedicated machines. First, beans are toasted before husking to remove the shell surrounding beans. The resulting cocoa goes through a pre-refiner before passing through a refiner to create a smoother consistency. Next, the ingredients enter a separator which ensures no grains are too large before going through a further refining stage. The last stage is conching in which the acidity of the cocoa is removed. The BAT solution combines the pre-refining, refining and conching stages into a single step, reducing the number of machines needed for the process to a single machine. Importantly, the machinery is designed to be easy to clean and does not release metal into the product. Crucially, it can also refine both products containing water (mix hydrated) and those without anhydrous, something that is not possible with current technology. The icing on the cake is that it comes at a comparatively low purchase price. The team built a prototype BAT refining head, to carry out tests. “The refining head is the processing step on which our innovation is based. We had a number of challenges to overcome with these tests, such as keeping temperature and quality constant across the whole product batch. Despite the complexity we managed to solve these with our design,” says Stefano Marello, project coordinator. Opportunities for smaller businesses The chocolate and cocoa market is a fast-evolving market. According to recent research, the demand for chocolate in Europe is predicted to grow by a compound annual growth rate of 3 %, between 2018 and 2022. While Europe is the world’s largest producer, the bulk of this production rests with six big multinationals.
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Why Hot Foil Stamping Helps Packaging To Shine Differentiation. It’s what every brand owner wants for their product, but in increasingly crowded markets, it is becoming harder and harder to achieve. Brand owners know that packaging is the key differentiator on the shelf, and special finishing techniques – such hot foil stamping and thermal embossing – can elevate their product compared to others, and provide consumers with a visual shortcut to the quality of what’s inside. Hot foil stamping is the process of using heat and pressure to apply metallic foil or holograms to materials such as light papers, carton board, laminated board, plastics and corrugated board. “In a world where we have very mature markets with limited opportunity for major growth, there is no question that products need to differentiate themselves somehow,” said Jacques Reymond, head of product marketing Business Unit Sheet-fed at BOBST. “Hot foil stamping helps to reinforce the value to the product and is often associated with premium products. Ultimately, the box is a marketing instrument, and by using hot foil stamping, you can convey the quality of what it inside.” The term can encompass simple flat foil stamping, deep embossing or embossing combined with foil stamping, hologram and holographic foil application and foil stamping combined with micro & structural embossing. Traditionally, gold or silver are the most common colors used for foiling, but a wide range of colored foils are available. Application across industries Hot foil stamping is used across a wide range of industry sectors, but most notably in food and drink (particularly confectionary such as premium chocolate, wine and liquor bottles, and other premium foods), cosmetics, electronics, banknotes, business cards, greeting cards and art work. There is no doubt about the value of embellishments like cold stamping foil. According to a study by the Foil & Specialty Effects Association (FSEA), hot foil stamping and other similar enhancements on product packaging can help attract consumer attention faster and keep attention longer than ordinary packaging. In another study of disposable single-serve coffee packaging, the packaging with gold foil attracted the study participants’ attention 2.5 times faster than the control packaging. It’s not just about looking good. Hot foil stamping is also used for its anti-counterfeiting properties, particularly in pharmaceuticals, and in technology such as smart phones.
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Sandblasting Air-abrasion (sandblasting) techniques have long been employed in restorative dentistry to enhance the mechanical adhesion between metals and adhesive resins. Sandblasting uses a high-speed stream of aluminum oxide particles propelled by compressed air to remove unfavorable oxides and contaminants, increase surface energy, bonding surface area, and surface roughness. Sandblasting in orthodontics has been implemented to improve the bond strength of new brackets/bands or to remove adhesive remnants from debonded brackets prior to rebonding.71 However, in vivo data from a randomized trial indicate that no significant difference exists in the bond failure rates of sandblasted and non-sandblasted brackets or in the ARI of debonded brackets.72 Finally, sandblaster has also been implemented directly on the tooth enamel surface as an alternative or adjunct to conventional acid-etching techniques, but as no randomized trial exists on this subject, the efficacy cannot be assessed in an evidence-based way at the present time. Grit-blasting or sandblasting, if available, may also be used. A specially-trained operator is needed to produce uniformity within pieces by sand blasting tank. A clean, uniform-size grit is essential for proper surface preparation with sandblasting. This may be a problem when treating GPR surfaces, and for that reason this technique is rarely used. After sanding or sandblasting, the surface is sometimes wiped with solvent such as MEK, acetone, toluene, trichloroethylene, Freon® TF, or Freon® TMC, depending on the known mold lubricants. In some cases, a solvent is used before and after abrading the surface. If water-break-free surfaces are not obtained, the procedure should be repeated. Glass-reinforced plastic laminates prepared for bonding by hand- and machine-sanding can be stored to 30 days at 23°C and 50% RH with no adverse effect on bond strength. Machine sanding gave slightly better results than hand sanding. Tear ply and sanding gave about the same results, but the tear-ply method has less risk of surface contamination. Variations in bond strength are more likely to occur as a result of changes in sanding techniques than by the difference in methods. In general, bond quality diminished with increased surface exposure time (SET). The best overall adhesive evaluated was epoxy film adhesive, which was found to be the least sensitive to the method of surface preparation. In general, the best result was obtained when GPR laminates were bonded within four hours after sanding. If absolutely necessary, bonding can be carried out after periods of time up to 14 days SET with only moderate strength loss. Brass is an alloy of copper and zinc. Sandblasting or other mechanical means of surface preparation may be used. Shot peening (which is a similar process to sandblasting, but has more controlled peening power, intensity, and direction) is a cold working process in which the surface of a part is bombarded with small spherical media called shot. Each piece of shot striking the material acts as a tiny hammer, imparting to the surface small indentations or dimples. In order for a dimple to be created, the surface fibers of the material must be yielded in tension. Below the surface, the fibers try to restore the surface to its original shape, thereby producing below the dimple a hemisphere of cold-worked material highly stressed in compression.
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Ball Valve - How They Work A ball valve is a shut off valve that controls the flow of a liquid or gas by means of a rotary ball having a bore. By rotating the ball a quarter turn (90 degrees) around its axis, the medium can flow through or is blocked. They are characterized by a long service life and provide a reliable sealing over the life span, even when the valve is not in use for a long time. As a result, they are more popular as a shut off valve then for example the gate valve. For a complete comparison, read our gate valve vs ball valve article. Moreover, they are more resistant against contaminated media than most other types of valves. In special versions, ball valves are also used as a control valve. This application is less common due to the relatively limited accuracy of controlling the flow rate in comparison with other types of control valves. However, the valve also offers some advantages here. For example, it still ensures a reliable sealing, even in the case of dirty media. Figure 1 shows a sectional view of a ball valve. Standard floating ball valves consist of the housing, seats, ball and lever for ball rotation. They include valves with two, three and four ports which can be female or male threaded or a combination of those. Threaded valves are most common and come in many varieties: with approvals for specific media or applications, mini ball valves, angled ball valves, ISO-top ball valves, with an integrated strainer or a bleed point and the list goes on. They have a wide range of options and a large operating range for pressure and temperature. For more information on a threaded connection, read our trunnion ball valve connection types article. Hydraulic Hydraulic ball valves are specially designed for hydraulic and heating systems due to their high operating pressure rating and hydraulic and heating oil resistance. These valves are made of either steel or stainless steel. Besides these materials, the seats also make hydraulic valves suitable for high operating pressure. The seats of these valves are made of polyoxymethylene (POM), which is suitable for high pressure and low temperature applications. The maximum operating pressure of hydraulic ball valves goes above 500 bar while the maximum temperature goes up to 80°C. Flanged Flanged ball valves are characterized by their connection type. The ports are connected to a piping system via flanges that are usually designed in accordance with a certain standard. These valves provide a high flow rate since they typically have a full-bore design. When choosing a flanged ball valve, besides the pressure rating, you also have to check the flange compression class which indicates the highest pressure this connection type can withstand. These ball valves are designed with two, three or four ports, they can be approved for specific media, have an ISO-top and everything else a standard quarter turn valve could have. They are typically made out of stainless steel, steel, or cast iron.
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Air Fryer If you are a family of two, you can make easy meals with a small air fryer. While there are many different sizes of air fryers available in the market, for a family of two, an air fryer from 2 to 4 quarts will be ideal. As these air fryers are small in size, they do not take much space on the kitchen shelf, and they cook ample food for two family members. You can cook a variety of meals in these air fryers without causing any food wastage. In this article, we will take a look at some of the popular air fryers that are ideal for a family of two. We will also compare each air fryer’s features along with the pros and cons of each air fryer. GoWISE is a well-known brand for air fryers of all sizes. You can find the GoWISE USA 3.7 quart air fryer ideal for the needs of a small family. If there are only two people in the family, this air fryer will suit their needs to cook quick meals of all kinds. The air fryer takes up little space on the kitchen counter and comes with a range of features that make air frying food fun and easy. There are eight presets on the 2.4l air fryer, and you can choose the dish you want to make from the buttons on the panel of the air fryer. The temperature and time settings are also available on the panel. The air fryer is ideal for cooking everything from chicken to french fries, fish, steak, pork, shrimp etc. The food is healthy to eat as it uses very little to no oil, and you can cook in the air fryer without the need to mess with oil or flames. The NUWAVE BRIO is a 3-Quart air fryer that makes the ideal amount of food for two people. If you have a small family, you can get this air fryer to cook food in small batches. The air fryer also has an air-flow design that makes delicious food quickly and efficiently. Another interesting feature is the Flavor-Infusion technology that allows you to cook food without needing to defrost it before putting it in the air fryer. The air fryer has an extensive cooking range so that you can cook all kinds of food at temperatures ranging from 100F to 400F. You can also choose from different cooking options depending on the dish that you want to cook. Whether you want to air fry, roast, grill, bake or reheat food, you can do it all. This is a small-sized air fryer that does not take too much space in the kitchen. You can also keep this 2.6l air fryer in a dorm room, a van, or an RV as needed. If you are looking for a small, powerful, and efficient air fryer, this is the machine you want to pick.
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How to choose the right retractable monitor? A retractable LCD monitor for use in aircraft and the like is supplied with power from a power supply that is secured in a fixed off-monitor location on the monitor's housing. The power supply also provides power for a motor assembly that controls a pivoting of the monitor between open and retracted positions. This configuration allows for a compact monitor assembly that can be stowed screen up within a restricted space housing, thus protecting the display from damage by passengers and presenting a pleasing appearance, while still pivoting the monitor by more than 90° to its open position. The motor that is used to pivot the monitor to the open position remains coupled to the monitor pivot mechanism during the retraction cycle, providing a back-emf that resists a spring force used to retract the monitor, and thereby cushion its retraction. A game machine has a display part connected so as to freely enable storage within a seat on which a player sits. The game machine has a display part for showing game images generated according to a game program and player input, an input reception part for receiving input from the player, a control part for executing the game program according to predetermined external input, including input from the input reception part, a seat part for enabling the player to sit, a storage part for storing the display part formed in the seat part, and a connection rod for connecting the display part to the storage part such as to freely enable storage thereof, of which one end is fixed to the seat part and the other end is connected to the display part. Arthur Holm is launching its first 24-in 4K motorized retractable monitor during ISE 2018, held next month in Amsterdam. The DB2 has 20° of adjustable inclination, the housing is made from solid aluminium and the operation button is placed on the top of the screen. The monitor provides a 2mm. double-sided anti-reflective black edged glass. The motorized retractable monitor with fixed tilt is configurable by way of a secondary LCD 2.2-in display, and by remote control, being able to be configurable and operational without having to remove the monitor from the furniture. When the display is connected to the AH ERT interface, the intuitive addressing system facilitates the address configuration easier due to a single accessible push button. The unit provides embedded speed and protection pre-sets to restore factory values and an auto-check diagnostic and internal protection functions as well as an auto calibration mode for mechanical speeds and safety parameters .It is firmware upgradeable through a USB port. A safety system detects obstructions (in this eventuality the unit stops). The adjustable mechanical parameters are operational via AHnet or ISD for calibration and mechanical adjustments. Adjustable parameters of brightness, contrast and backlight are available via RS- 422. An auto calibration mode is available for mechanical speeds and safety parameters. So, your screen, cheap or expensive, if it is non-tensioned (cheap ones aren't) will likely have or develop waves.
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The PCR tube is highly optimized to achieve excellent PCR Supplies performance in various thermal cyclers. These innovative and RNase-free PCR tubes are the results of years of research on the best design of PCR tubes, coupled with meticulous craftsmanship to ensure that each product is as perfect as the first product. The results speak for themselves, and we are happy to introduce our ultimate PCR tube to the world. We will explore some of the defining characteristics of these advanced thin-walled PCR tubes. RNase-free PCR tubes with broad thermal cycler compatibility Our RNase free PCR Tubes are compatible with all the most common thermal cyclers on the market. We make sure to optimize their design to ensure PCR performance that is agnostic to the thermal cycler. This means that no matter which brand of thermal cycler you use, their performance is the same. The pipette is one of the most commonly used handheld instruments in a research laboratory and the model of the pipette is chosen based on your needs for performance, ergonomics and quality. But it doesn’t end there - you may have the most advanced pipette on the market but a poor quality tip means that the reproducibility of your results may be at risk. Don’t be caught out; the fact is that quality Pipette Tips are critical to ensuring that the correct volume of liquid is aspirated and dispensed and that your samples are not contaminated in the process. Here are some quick hints to ensure that your pipette tips are a perfect match for your pipette of choice and do not compromise your lab work. The Reagent Bottle is a special container for various liquids and solid reagents in the laboratory. The shape of the reagent bottle is mainly divided into narrow mouth and wide mouth. Since reagent bottles are only used for normal temperature storage reagents, they are usually made of sodium calcium plain glass. In order to ensure a certain strength, the bottle wall is generally thicker. Reagent bottle is divided into narrow mouth or wide mouth, clear or amber,and with stopper or without stopper. Among them, glass stopper, no matter small mouth, wide mouth, should have inside ground sand processing craft. The specifications of HDPE Reagent Bottles are expressed in volume size, small to 30mL, 60mL, ranging from thousands to tens of thousands of ml. Precautions for use: (1) when the reagent bottle is not used, you need to slip the paper between the bottle stopper and the bottle mouth to prevent adhesion. As mentioned above, none of the reagent bottles can be used for heating. (2) according to holding the physical and chemical properties of the reagents needed reagent bottles of the general principle is: dress up solid reagent selection jar, holding liquid reagent - choose fine mouth bottle, all see light is easy to break down, or metamorphic reagent to choose a brown bottle, holding low boiling point volatile reagent chooses frosted PP Reagent Bottles, holding an alkaline reagent selection with a rubber plug reagent bottles, and so on. If the reagent has the above multiple physical and chemical indexes, the appropriate reagent bottle can be selected according to the above principles. (3) some special reagents, such as hydrofluoric acid, are not available in any glass reagent bottles and are used in plastic bottles.
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Automatic classification of granite tiles through colour and texture features This paper is about the development of an expert system for automatic classification of granite tiles through computer vision. We discuss issues and possible solutions related to image acquisition, robustness against noise factors, extraction of visual features and classification, with particular focus on the last two. In the experiments we compare the performance of different visual features and classifiers over a set of 12 granite classes. The results show that classification based on colour and texture is highly effective and outperforms previous methods based on textural features alone. As for the classifiers, Support Vector Machines show to be superior to the others, provided that the governing parameters are tuned properly. Highlights We discuss the development of an expert system for automatic classification of granite tiles. We propose new approaches to granite classification based on combined colour and texture analysis. We evaluate the performance of different visual descriptors and classifiers. Combination of colour and texture features proves highly effective in discriminating granite appearance. Classification based on SVM support vector classification outperforms the other methods. People have used granite for thousands of years. It is used as a construction material, a dimension stone, an architectural stone, a decorative stone, and it has also been used to manufacture a wide variety of products. Granite is used in buildings, bridges, paving, monuments, and many other exterior projects. Indoors, polished granite slabs and tiles are used in countertops, tile floors, stair treads and many other design elements. Granite is a prestige material, used in projects to produce impressions of elegance and quality. Some interesting and common uses of granite are shown in the photo collection below. The definition of "granite" varies. A geologist might define granite as a coarse-grained, quartz- and feldspar-bearing igneous rock that is made up entirely of crystals. However, in the dimension stone trade, the word "granite" is used for any feldspar-bearing rock with interlocking crystals that are large enough to be seen with the unaided eye. By this classification, rocks such as anorthosite, gneiss, granite, granodiorite, diabase, monzonite, syenite, gabbro and others are all sold under the trade name of "granite." The quality control process in stone industry is a challenging problem to deal with nowadays. Due to the similar visual appearance of different rocks with the same mineralogical content, economical losses can happen in industry if clients cannot recognize properly the rocks delivered as the ones initially purchased. In this paper, we go toward the automation of rock-quality assessment in different image resolutions by proposing the first data-driven technique applied to granite tiles classification. Our approach understands intrinsic patterns in small image patches through the use of Convolutional Neural Networks tailored for this problem. Experiments comparing the proposed approach to texture descriptors in a well-known dataset show the effectiveness of the proposed method and its suitability for applications in some uncontrolled conditions, such as classifying granite slab under different image resolutions. These ceramic and granite tiles from Italian company Cerdomus are unusual, modern and effortlessly beautiful. The ceramic-granite made tiles mimic gorgeous wood flooring. Their unique appearance brings dynamic contrasts into a modern interior design, offering practical, convenient flooring. Wood-like floor tiles are a timeless choice that turns living spaces into luxurious and unique rooms, filled with comfort, warmth and timeless elegance. These modern floor tiles are excellent for creating an original interior design, adding a contemporary touch to home decorating. Suitable for decorating almost all home interiors, from bathrooms, laundry rooms and entryways to kitchens and living rooms. The nature of granite ensures durability and practicality, exceeding over marble or man-made stone. The durable and attractive floor tiles are made of ceramic-granite. Encouraging to experiment and create fresh and sophisticated floor decor. Designed for few stylish collections, ideal for different interior design and home decorating styles. From country home style to classic, contemporary and eco style. Numerous tile colour shades reflect natural wood yellowish to bleached white and brown colours of natural wood.
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TURN YOUR KID’S ARTWORK INTO A SCRAPBOOK The kids have only been in school for two months, but the papers and artwork are piling up. Normally I keep a select pieces of artwork and recycle the rest (after the kids are in bed). This year I’m taking a different approach. Armed with my Straight Talk Samsung Galaxy S6, I’m taking pictures of their artwork and turning it into a kids art scrapbook. What, you don’t have time to make a scrapbook? Don’t worry, this scrapbook is low maintenance and costs less than $10 to make. Even if you’re not crafty, you’ll be surprised by how simple it is to turn your kid’s artwork into a scrapbook. Grab your smartphone and let’s get started! Now grab that stack of artwork you have piled up in the corner. Pull out your favorite pieces (or have your child help) to photograph. Natural lighting is the best, so photograph outside or near a window. I set up a photography station on our patio. I already have foam boards for my food photography, but you can also use posterboard or cardboard. Make sure it’s bigger than your child’s artwork and the board is a solid neutral color. Here I used black foam board. Set the foam board on a chair or something sturdy. Alternately, you can tape it to a wall or window. Take a 3″ piece of masking or washi tape and roll it onto itself. Attach it to the board. You’re essentially creating a reusable sticky surface to attach the artwork to the board. The hobby of scrapbooking is quite popular. People use kids' scratch coding book to tell a story, chronicle the history of their family, and preserve cherished memories. Most scrapbookers are also having fun and relieving stress. If you have thought about giving scrapbooking a whirl but are clueless where to start, this guide will help. Even if you are not the artistic type, you can still make lovely pages when following some simple rules and guidelines. There are many types of glues sold for scrapbooking; decide what kind you prefer. Examples are glue sticks, liquid glue pens, photo tape, foam dots, and more. The glue needs to photo-safe and acid-free. Albums and Sheet Protectors Albums come in a variety of sizes; the standard size that most beginners use is 12 x 12 inch. This size allows you to use many sizes of photos and still have room for other scrapbooking elements. Make sure the page protectors are Mylar, polypropylene, or polyethylene. Any other page protector will damage and fade your pages with time. Cutting Tools You will want large and small straight edge pairs of scissors. Other options include decorative scissors, paper trimmers, and shape cutters. For advanced art stencil book, a digital die-cut machine is useful.
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Calculation Inductance of Toroidal Inductor Wound by Rectangular Cross-Sectional Wire In this article, we present two methods for calculation of the inductance of toroidal core power inductors wound by rectangular cross-sectional wire, considering that the current density is inversely proportional to the circular coil radius. The first method is to simplify the helical toroidal coil into a thick-walled toroidal, and based on Grover’s toroidal inductor formula, the inductance is obtained by calculation the magnetic flux and the calculation method is simple, but the applicability is poor. The second method is to simplify the helical toroidal coil into a collection of self-closing circular coils, the calculation method is complex but has high accuracy, and the mutual inductance between the circular coils is calculated by the filament method based on the adjusted Grover’s mutual inductance of circular coils with inclined axes. We verify the adjusted Grover’s mutual inductance of filamentary circular coils with inclined axes and the mutual inductance between inclined circular coils with a rectangular cross section. Finally, we compared and analyzed the results calculated by the two methods proposed in this article and the results calculated by the finite element method. The various advantages of toroidal inductors, which are cooler, smaller and more EMI-resistant are discussed. With toroidal inductors, there is an advantage to maintaining a single layer of windings due to which the inductor behaves closer to an ideal component of lower levels of parasitic capacitance. Multi-layer toroidal inductors involve both turn-to-turn capacitance and layer-to-layer capacitance and a very significat start/finish gap capacitance since there is no start/finish gap. This increases the total amount of parasitic capacitance by orders of magnitude. This paper presents a micromachined implementation of embedded toroidal solenoids for high-performance on-chip inductors and transformers, which is highly demanded in radio-frequency integrated circuits (RFICs). Microfabricated on CMOS compatible silicon wafers with post-CMOS micromachining techniques, the RF toroidal components can constrain the magnetic flux into a well-defined path and away from other on-chip RF devices, thereby, being in favor of decrease in RF loss, increase in Q-factor and elimination of electromagnetic interference. By using a technical combination of an anisotropic wet etch and an isotropic dry etc., the micromachined toroidal structure can be used for the formation of metal solenoid by copper electroplating. Processed under low temperature (Max 120 °C for photoresist hard-baking), the three mask microfabrication can be compatible with CMOS IC fabrication in a post-process way. The formed toroidal inductors with 4.92 nH and 8.48 nH inductance are tested, and we obtain maximum Q-factors of 25.7 and 17.8 at 3.6 GHz and 3.1 GHz, while the self-resonant frequencies are 17.3 GHz and 7.4 GHz, respectively. On the other hand, two types of toroidal transformers are also formed and tested, resulting in satisfactory RF-performance. Therefore, the novel techniques for close-loop solenoid inductors are promising for high-performance RF ICs. In electrical engineering a toroidal inductor is used to measure or monitor the electric currents of an AC power circuit as a function of the harmonic distortion [1,2]. A galvanically isolated current measurement is required, such that the advantages of lower losses nd measurement signals processed directly must be attained [3]. The ferrite core toroid inductors produces a reduced current accurately proporonal to the measured current. The toroidal inductor can be also commonly used for feedback control, and other applications [4].The design method of toroidal inductors have been developed by a non iterative method, which introduce an equation for estimation of the core size required as function of the wanted inductance and the maximum values specified for induction and current [5]. Another method solution consists in modeling inductors along with the equivalent circuits, calculation of the leakage inductance, core material characteristics, and geometrical configuretion for the minimization of volume inductors in order to simplify the design procedure [3]. Nevertheless, the trend for the current monitoring is driven by cost reduction, an increased functionality, and limited weight/space in some applications [3,4].This finally results in constantly increasing frequencies, which comes along with and increased bandwidth and poor stability.Based on electric and magnetic properties, like saturation magnetization, and toroidal-core losses, here is proposed the possibility of application of the grain-oriented silicon-iron cores for current monitoring, because these can reduce phase error and improve its accuracy in measurements of AC current at low frequencies (50 - 60 Hz) [6,7]. A simple method for toroidal-inductor design at minimum losses is suggested to calculate several inductors accepting a broad tolerance of the core material features.In general, the inductor design procedure described in literature makes use of numerous monograms, and the final result is achieved through several iterations. In special, toroidal inductors have been designed by several engineers with tedious methods [8-10]. For that reason, the lack of deeper understanding of the fundamental electromagnetic laws, it makes many engineers to consider the design of inductive components a difficult task.The purpose here is to explain a design method based on well-known tools by engineers [11]; presenting in a simple and easy way the relationships that exists between equivalent circuit and transfer function of a toroidal inductor. The proposed work is developed to meet the following objectives:1) To explain the relationship between equivalent circuit and magnetic parameters of a toroidal inductor;2) To develop the method based on normalized parameters;3) To demonstrate the method validation with a current-signal sensor and evaluate the EN-50160-2-2 standard as a function of single harmonic distortion (SHD) in home use loads [1]. The design method for an anti interference toroidal inductor is proposed as an alternative to power-quality evaluation. The method is based on well-known tools by the engineers in which is presented the relationships that exist between equivalent circuit and transfer function of a toroidal inductor. The proposed design method has been explained with normalized functions based on physical parameters of a toroidal inductor. This work presents the main arguments of the suggested methodology and as demonstration of the design method as function of normalized parameters, is developed a current-signal sensor which has been validated in the laboratory by the EN-50160-2-2 standard to evaluate the power quality in home use loads.
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The integrated impact indicator revisited We propose the I3* indicator as a non-parametric alternative to the journal impact factor (JIF) and h-index. We apply I3* to more than 10,000 journals. The results can be compared with other journal metrics. I3* is a promising variant within the general scheme of non-parametric I3 indicators introduced previously: I3* provides a single metric which correlates with both impact in terms of citations (c) and output in terms of publications (p). We argue for weighting using four percentile classes: the top-1% and top-10% as excellence indicators; the top-50% and bottom-50% as shock indicators. Like the h-index, which also incorporates both c and p, I3*-values are size-dependent; however, division of I3* by the number of publications (I3*/N) provides a size-independent indicator which correlates strongly with the 2- and 5-year journal impact factors (JIF2 and JIF5). Unlike the h-index, I3* correlates significantly with both the total number of citations and publications. The values of I3* and I3*/N can be statistically tested against the expectation or against one another using chi-squared tests or effect sizes. A template (in Excel) is provided online for relevant tests. Citations create links between publications; but to relate citations to publications as two different things, one needs a model (for example, an equation). The journal impact factor (JIF) indexes only one aspect of this relationship: citation impact. Using the h-index, papers with at least h citations are counted. One can also count papers with h2 or h/2 citations (Egghe 2008). This paper is based on a different and, in our opinion, more informative model: the Integrated Impact Indicator I3. The 2-year JIF was outlined by Garfield and Sher (1963; cf. Garfield 1955; Sher and Garfield 1965) at the time of establishing the Institute for Scientific Information (ISI). JIF2 is defined as the number of citations in the current year (t) to any of a journal’s publications of the two previous years (t − 1 and t − 2), divided by the number of citable items (substantive articles, reviews, and proceedings) in the same journal in these two previous years. Although not strictly a mathematical average, JIF2 provides a functional approximation of the mean early citation rate per citable item. A JIF2 of 2.5 implies that, on average, the citable items published 1 or 2 years ago were cited two and a half times. Other JIF variants are also available; for example, JIF5 covers a 5-year window.Footnote1 The central problem that led Garfield (1972, 1979) to use the JIF when developing the Science Citation Index, was the selection of journals for inclusion in this database. He argued that citation analysis provides an excellent source of information for evaluating journals. The choice of a 2-year time window was based on experiments with the Genetics Citation Index and the early Science Citation Index (Garfield 2003, at p. 364; Martyn and Gilchrist 1968). However, one possible disadvantage of the short term (2 years) could be that “the journal impact factors enter the picture when an individual’s most recent papers have not yet had time to be cited” (Garfield 2003, p. 365; cf. Archambault and Larivière 2009). Bio-medical fields have a fast-moving research front with a short citation cycle, and JIF2 may be an appropriate measure for such fields but less so for other fields (Price 1970). In the 2007 edition of Journal Citation Reports (reissued for this reason in 2009) a 5-year JIF (JIF5, considering five instead of only two publication years) was added to balance the focus on short-term citations provided by JIF2 (Jacsó 2009; cf. Frandsen and Rousseau 2005).Footnote2 The skew in citation distributions provides another challenge to the evaluation (Seglen 1992, 1997). The mean of a skewed distribution provides less information than the median as a measure of central tendency. To address this problem, McAllister et al. (1983, at p. 207) proposed the use of percentiles or percentile classes as a non-parametric tilt indicators (Narin 1987Footnote3; see later: Bornmann and Mutz 2011; Tijssen et al. 2002). Using this non-parametric approach, and on the basis of a list of criteria provided by Leydesdorff et al. (2011), two of us first developed the Integrated Impact Indicator (I3) based on the integration of the quantile values attributed to each element in a distribution (Leydesdorff and Bornmann 2011). Since I3 is based on integration, the development of I3 presents citation analysts with a construct fundamentally different from a methodology based on averages. An analogy that demonstrates the difference between integration and averaging is given by basic mechanics: the impact of two colliding bodies is determined by their combined mass and velocity, and not by the average of their velocities. So, it can be argued that the gross impact of the journal as an entity is the combined volume and citation of its contents (articles and other items); but not an average. Journals differ both in size (the number of published items) and in the skew and kurtosis of the distribution of citations across items. A useful and informative indicator for the comparison of journal influences should respond to these differences. A citation average cannot reflect the variation in both publications and citations but an indicator based on integration can do so. One route to indexing both performance and impact via a single number has been provided by the h-index (Hirsch 2005) and its variants (e.g., Bornmann et al. 2011a, b; Egghe 2008). However, the h-index has many drawbacks, not least mathematical inconsistency (Marchant 2009; Waltman and Van Eck 2012). Furthermore, Bornmann et al. (2008) showed that the h-index is mainly determined by the number of papers (and not by citation impact). In other words, the impact dimension of a publication set may not be properly measured using the h-index. One aspect that I3 has in common with the h-index is that the focus is no longer on impact as an attribute but on the information production process (Egghe and Rousseau 1990; Ye et al. 2017). This approach could be applied not only to journals but also to other sets of documents with citations such as the research portfolios of departments or universities. In this study, however, we focus on journal indicators.
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Refrigerators Now here's a cool idea: a metal box that helps your food last longer! Have you ever stopped to think how a refrigerator keeps cool, calm, and collected even in the blistering heat of summer? Food goes bad because bacteria breed inside it. But bacteria grow less quickly at lower temperatures, so the cooler you can keep food, the longer it will last. A food meat refrigerator is a machine that keeps food cool with some very clever science. All the time your refrigerator is humming away, liquids are turning into gases, water is turning into ice, and your food is staying deliciously fresh. Let's take a closer look at how a refrigerator works! What’s your favorite late night snack – that go-to treat that melts away the troubles of the day as you curl up in front of the TV? Perhaps it’s a creamy bowl of Rocky Road or maybe some delicious, spicy Szechuan chicken left over from a recent take-out feast. Refrigerator-finds like these may make you feel bad about indulging in guilty pleasures, but at least you don't have to feel bad about how high your energy bill will be to cure your cravings. That’s because of innovative technology and meaningful energy conservation standards put into place by the Office of Energy Efficiency and Renewable Energy's Building Technologies Program. In recent decades, the Energy Department has led technological innovation that vastly improved the energy efficiency of our refrigerators and freezers (and thousands of other household appliances). As a result, it’s a lot easier on your pocket and on the environment to keep that ice cream at peak frosty perfection. In fact, today’s refrigerators use only about 25 percent of the energy that was required to power models built in 1975. Even while continually improving efficiency to meet standards, refrigerators have increased in size by almost 20 percent, have added energy-using features such as through-the-door ice, and provide more benefits than ever before. Refrigerators today can be customized to fit consumer needs with touch-screen displays, glass doors, or even a beer tap. The dramatic rise in efficiency began in response to the oil and energy crises of the 1970s when refrigerators typically cost about $1,300 when adjusted for inflation, a hefty price to pay for an energy waster. Refrigeration labels and standards have improved efficiency by two percent per year since 1975. Due to research, useful tools, partnerships with utilities and other organizations, and market initiatives that helped enable top open air curtain refrigerator and other appliance standards, the Energy Department has helped avoid the construction of up to 31 1-GW power plants with the energy saved since the first Federal standards in 1987. That’s the same amount of electricity consumed by Spain annually. The Department will soon have strengthened the standards for household refrigerators three times. Each time, manufacturers have responded with new innovations that enabled their products to meet the new requirements and often to exceed them. Refrigerators that performed above and beyond the minimum standards qualified for the ENERGY STAR label, motivated consumers to care about energy usage, and primed the market for continued efficiency improvements. Decades worth of progressive energy-efficiency standards for refrigerators have translated into big savings for consumers. Compared to refrigerators of the 1970s, today's refrigerators save the nation about $20 billion per year in energy costs, or $150 per year for the average American family. The next proposed increase in refrigerator and freezer efficiency -- scheduled to take effect in 2014 -- will save the nation almost four and a half quadrillion BTUs over 30 years. That’s three times more than the total energy currently used by all refrigeration products in U.S. homes annually. It’s also the equivalent amount of energy savings that could be used to power a third of Africa for an entire year The Energy Department is continuing to invest even more in future innovations for energy efficient products. So go ahead and indulge with those late night snacks and frozen treats. Your fridge has you covered. To learn more about Appliance Standards and how they save consumers money go to the Building Technologies Program website. In this position, Roland Risser was responsible for leading all of EERE's applied research, development and demonstration for renewable energy, including geothermal, solar, and wind and water power.In this position, Roland Risser was responsible for leading all of EERE's applied research, development and demonstration for renewable energy, including geothermal, solar, and wind and water power.
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What is a Filter Press? In some batch filtration processes, highly permeable suspensions dewater fast compared to the rest of the process. This work explores the impact of fast-filtering compressible materials on the throughput of fixed-chamber filter presses. The dewatering properties for a compressible yet highly permeable minerals processing slurry are used as inputs to a standard filter press model to explore the effects of operating and design parameters. For fast-filtering materials, maximum throughput is achieved with wide cavities and minimal handling time, while membrane resistance can be significant. Pressure affects the maximum achievable concentration, as given by the strength of the material. Overall, this work demonstrates the combined use of material characterisation and device modelling for filter press optimisation. This article answers three common inquiries. What is a filter press? How does a filter press work? What is a filter press used for? We’ll also give you some advice on sizing your equipment (including your feed pump). Our Sales and Service Team is looking forward to answering any other questions you might have. WHAT IS A FILTER PRESS? A pressure leaf filter is a batch operation, fixed volume machine that separates liquids and solids using pressure filtration. A slurry is pumped into the filter press and dewatered under pressure. It is used for water and wastewater treatment in a variety of different applications ranging from industrial to municipal. M.W. Watermark manufacturers filter presses ranging from .06-600 cubic feet. Slurry is pumped into the filter press. The solids are distributed evenly during the feed (fill) cycle. Solids begin to build on the filter cloth. Most of the solid/liquid separation is done by the filter cake building on the cloths. At first some fines may pass through the cloth (1), but eventually the solids begin to form a layer on the filter cloth (2) much like a pre-coat. That layer traps the fine particles and forms a filter cake (3). As the vertical pressure leaf filter builds pressure, the solids build within the chambers until they are completely full of filter cake. When the chambers are full, the fill cycle is complete. The filtrate (liquid) exits the filter pack (plates) through the corner ports into the manifold; when the correct valves in the manifold are open, the filtrate exits the press through one single point, the filtrate outlet. HOW LONG DOES A FILTER PRESS CYCLE TAKE? The Total Cycle time is the Fill Cycle time plus a constant. For presses of 125 cubic feet and under this constant is usually around 45 minutes. This is the time required to close/open the press, perform the Air Blow Down and discharge the filter cake. If the particular application requires operations such as Core Blow or Cake Wash, for example, this constant is longer. HOW LONG DOES A FILL CYCLE TAKE? The Fill Cycle is dependent on many parameters. The most important parameter is the nature of material to be dewatered. A sand slurry releases its water readily and dewaters quickly. On the other hand, an Aluminum Hydroxide waste slurry from beverage can manufacture does not readily release its water and dewaters slowly. The next most important parameter is the concentration of the solids by weight in the slurry. The Fill Cycle for a 5% solids slurry is about twice as long as a 10% solids slurry (with all other parameters being equal). This is because the press has to process half of the water to fill with solids.
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60 years of integrated circuits An integrated circuit is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated. Sometimes called a chip or microchip. The invention of the integrated circuit made technologies of the Information Age feasible. ICs are now used extensively in all walks of life, from cars to toasters to amusement park rides. Integrated circuits (ICs) are self-contained circuits with many separate components such as transistors, diodes, resistors and capacitors etched into a tiny silicon chip. Related Journals of Integrated circuit Journal of Physical Chemistry & Biophysics, Journal of Electrical & Electronic Systems, Analog Integrated Circuits and Signal Processing, IEEE Radio Frequency Integrated Circuits Symposium, IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Journal of Integrated Circuits and Systems, Proceedings of the Custom Integrated Circuits Conference. On 12 September 1958, Jack Kilby of Texas Instruments demonstrated a working integrated circuit1. The circuit was a phase-shift oscillator that used transistor, resistor and capacitor elements built from a single piece of germanium; the elements were connected into a circuit with the help of thin gold wires. A few months later, Robert Noyce, working at Fairchild Semiconductor, proposed a monolithic integrated circuit2. This planar design was based on silicon and used lines of aluminium, deposited on the insulating silicon dioxide layer that can form on the surface of silicon wafers, to connect the different circuit elements in the single chip. By 1960, a team of engineers at Fairchild Semiconductor had turned this design into a reality. Electronic components, which had previously been discrete units connected with individual wires, could now be integrated into the same piece of semiconducting material. In the 60 years since Kilby’s initial demonstration, progress in STM8S207C8T6 has been astounding. Noyce would go on to co-found Intel, and just how far the company — and the design of integrated circuits — has come in that time is highlighted in this issue of Nature Electronics. In a News & Views article, Suman Datta of the University of Notre Dame reports on Intel’s 10-nanometre logic technology. With this latest design iteration3, the company has introduced a number of unconventional approaches to improve transistor density and performance, including a technique to reduce the spacing between cells and a method to add gate contacts directly over the active area. As a result, they can deliver around 100 million transistors per square millimetre — a transistor density that is 2.7 times higher than that of their previous 14-nm technology, which was introduced in 2014. At this level of complexity, developments are far from straightforward. Earlier this year, it emerged that Intel have encountered problems in the manufacturing of the 10-nm chips, leading to delays in mass production4; the chips are now expected to ship in volume in 2019. And in the past few weeks, GlobalFoundries announced5 that they would stop development of their 7-nm chips (thought to be comparable to Intel’s 10-nm technology). The continued scaling of silicon complementary metal–oxide–semiconductor (CMOS) technology beyond these levels is also likely to prove increasingly difficult. But, at the same time, the applications of computers are evolving, and demand the processing of ever larger amounts of data. As a result, the search for strategies and materials beyond silicon, which could help create the next generation of devices and integrated circuits, remains vital. Carbon nanotubes are among the contenders fighting for a place in the future of electronics, and in our Reverse Engineering column in this issue, Cees Dekker recounts how the first carbon nanotube transistor was built back in 1998. A related contender in this fight is two-dimensional materials, as well as the vertical stacks of different two-dimensional materials known as van der Waals heterostructures. These materials have been used to build a range of promising devices and some basic circuits — even a microprocessor6. The unique challenges involved in trying to build practical integrated circuits from two-dimensional materials are just starting to be addressed, but innovative ideas are emerging. For example, in an Article in this issue, Moon-Ho Jo and colleagues illustrate how a scanning light probe can be used to write monolithic integrated circuits For ST on two-dimensional molybdenum ditelluride (MoTe2). The researchers — who are based at the Institute for Basic Science in Pohang, Pohang University of Science and Technology, the Korea Institute of Materials Science, and Yonsei University — first pattern gold electrodes onto the MoTe2. Then, by shining the light probe (a visible laser) onto the electrodes, the semiconducting MoTe2 beneath can be converted from an n-type semiconductor to a p-type semiconductor. (With silicon CMOS technology, such doping is typically achieved using ion implantation.) The approach allows the two-dimensional material to be doped precisely and quickly, and Jo and colleagues use it to create arrays of bipolar junction transistors and circular diodes.
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Engineering Essentials: Fundamentals of Hydraulic Pumps When a hydraulic pump operates, it performs two functions. First, its mechanical action creates a vacuum at the pump inlet which allows atmospheric pressure to force liquid from the reservoir into the inlet line to the pump. Second, its mechanical action delivers this liquid to the pump outlet and forces it into the hydraulic system. A pump produces liquid movement or flow: it does not generate pressure. It produces the flow necessary for the development of pressure which is a function of resistance to fluid flow in the system. For example, the pressure of the fluid at the pump outlet is zero for a pump not connected to a system (load). Further, for a pump delivering into a system, the pressure will rise only to the level necessary to overcome the resistance of the load. Classification of pumps All pumps may be classified as either positive-displacement or non-positive-displacement. Most pumps used in hydraulic systems are positive-displacement. A non-positive-displacement pump produces a continuous flow. However, because it does not provide a positive internal seal against slippage, its output varies considerably as pressure varies. Centrifugal and propeller pumps are examples of non-positive-displacement pumps. If the output port of a non-positive-displacement pump were blocked off, the pressure would rise, and output would decrease to zero. Although the pumping element would continue moving, flow would stop because of slippage inside the pump. In a positive-displacement pump, slippage is negligible compared to the pump's volumetric output flow. If the output port were plugged, pressure would increase instantaneously to the point that the pump's pumping element or its case would fail (probably explode, if the drive shaft did not break first), or the pump's prime mover would stall. Positive-displacement principle A positive-displacement pump is one that displaces (delivers) the same amount of liquid for each rotating cycle of the pumping element. Constant delivery during each cycle is possible because of the close-tolerance fit between the pumping element and the pump case. That is, the amount of liquid that slips past the pumping element in a positive-displacement pump is minimal and negligible compared to the theoretical maximum possible delivery. The delivery per cycle remains almost constant, regardless of changes in pressure against which the pump is working. Note that if fluid slippage is substantial, the harvester hydraulic pump is not operating properly and should be repaired or replaced. Positive-displacement pumps can be of either fixed or variable displacement. The output of a fixed displacement pump remains constant during each pumping cycle and at a given pump speed. The output of a variable displacement pump can be changed by altering the geometry of the displacement chamber. Other names to describe these pumps are hydrostatic for positive-displacement and hydrodynamic pumps for non-positive-displacement. Hydrostatic means that the pump converts mechanical energy to hydraulic energy with comparatively small quantity and velocity of liquid. In a hydrodynamic pump, liquid velocity and movement are large; output pressure actually depends on the velocity at which the liquid is made to flow.
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What is a 3-Phase Motor and How Does it Work? Three-phase motors (also annotated numerically as 3-phase motors) are widely used in industry and have become the workhorse of many mechanical and electromechanical systems because of their relative simplicity, proven reliability, and long service life. Three-phase motors are one example of a type of induction motor, also known as an asynchronous motor, that operates using the principals of electromagnetic induction. While there are also single-phase induction motors available, those types of induction motors are used less frequently in industrial applications but are widely used in domestic applications such as in vacuum cleaners, refrigerator compressors, and air conditioners, owing to the use of single-phase AC power in homes and offices. In this article, we will discuss what a three-phase motor is and describe how it operates. To access other resources about motors, consult one of our other motor guides covering AC motors, DC motors, Induction motors, or the more general article on the types of motors. A full list of related motor articles is found in the section on related articles. To understand single phase motor, it is useful to first understand three-phase power. In electrical power generation, alternating current (AC) that is created by a generator has the characteristic that its amplitude and direction changes with time. If shown graphically with the amplitude on the y-axis and time on the x-axis, the relationship between the voltage or current vs. time would resemble a sine wave as shown below: Electrical power carried to homes is single-phase, meaning that there is one current-carrying conductor plus a neutral connection and a ground connection. In three-phase power, which is used in industrial and commercial settings to run larger machinery that has greater power needs, there are three conductors of electrical current, each of which is operating at a phase difference of 120o of 2π/3 radians apart. If viewed graphically, each phase would appear as a separate sine wave, which then combines as shown in the image below: Three-phase motors are powered from the electrical voltage and current that is generated as three-phase input power and is then used to produce mechanical energy in the form of a rotating motor shaft. What is a 3-Phase Motor? Three-phase motors are a type of AC motor that is a specific example of a reducer motor. These motors can be either an induction motor (also called an asynchronous motor) or a synchronous motor. The motors consist of three main components – the stator, the rotor, and the enclosure. The stator consists of a series of alloy steel laminations around which are wound with wire to form induction coils, one coil for each phase of the electrical power source. The stator coils are energized from the three-phase power source. The rotor also contains induction coils and metal bars connected to form a circuit. The rotor surrounds the motor shaft and is the motor component that rotates to produce the mechanical energy output of the motor. The enclosure of the motor holds the rotor with its motor shaft on a set of bearings to reduce the friction of the rotating shaft. The enclosure has end caps that hold the bearing mounts and house a fan that is attached to the motor shaft which spins as the motor shaft turns. The spinning fan draws ambient air from outside the enclosure and forces the air across the stator and rotor to cool the motor components and dissipate heat that is generated in the various coils from the coil resistance. The enclosure also typically has raised mechanical fins on the exterior that serve to further conduct heat to the outside air. The end cap will also provide a location to house the electrical connections for the three-phase power to the motor.
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