[liruzhi1weqwe37]

Solder is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable for use as solder should have a lower melting point than the pieces to be joined. The solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder used in making electrical connections also needs to have favorable electrical characteristics. Soft solder typically has a melting point range of 90 to 450 °C (190 to 840 °F; 360 to 720 K), and is commonly used in electronics, plumbing, and sheet metal work. Alloys that melt between 180 and 190 °C (360 and 370 °F; 450 and 460 K) are the most commonly used. Soldering performed using alloys with a melting point above 450 °C (840 °F; 720 K) is called "hard soldering", "silver soldering", or brazing. In specific proportions, some alloys are eutectic — that is, the alloy's melting point is the lowest possible for a mixture of those components, and coincides with the freezing point. Non-eutectic alloys can have markedly different solidus and liquidus temperatures, as they have distinct liquid and solid transitions. Non-eutectic mixtures often exist as a paste of solid particles in a melted matrix of the lower-melting phase as they approach high enough temperatures. In electrical work, if the joint is disturbed while in this "pasty" state before it fully solidifies, a poor electrical connection may result; use of eutectic solder reduces this problem. The pasty state of a non-eutectic solder can be exploited in plumbing, as it allows molding of the solder during cooling, e.g. for ensuring watertight joint of pipes, resulting in a so-called "wiped joint".
Solder pallet, the basic unit of surface mount assembly, is used to form the solder pallet pattern of the circuit board, that is, a combination of various solder pallet materials designed for special component types. When a solder pallet structure is not designed correctly, it is difficult, sometimes impossible, to achieve the intended solder joint. There are two words for solder pallet: Land and Pad, and are often used interchangeably; however, functionally, Land is a two-dimensional surface feature used for surface mountable components, while Pad is a three-dimensional feature used for pluggable components. As a general rule, Land does not include PTH, plated through-hole. Vias are plated through holes (PTHs) that connect different circuit layers. A blind via is a buried via that connects the outermost layer and one or more inner layers, and only connects the inner layers.
Fiberglass is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinyl ester resin—or a thermoplastic. Cheaper and more flexible than carbon fiber, it is stronger than many metals by weight, non-magnetic, non-conductive, transparent to electromagnetic radiation, can be molded into complex shapes, and is chemically inert under many circumstances. Applications include aircraft, boats , automobiles, bath tubs and enclosures, swimming pools, hot tubs, septic tanks, water tanks, roofing, pipes, cladding, orthopedic casts, surfboards, and external door skins. Other common names for fiberglass are glass-reinforced plastic (GRP), glass-fiber reinforced plastic (GFRP) or GFK (from German: Glasfaserverstärkter Kunststoff). Because glass fiber itself is sometimes referred to as "fiberglass", the composite is also called fiberglass-reinforced plastic (FRP). This article will adopt the convention that "fiberglass" refers to the complete fiber-reinforced composite material, rather than only to the glass fiber within it. Carbon-fiber-reinforced polymer is a similar composite material in which the reinforcement fiber is carbon fibers.
Fiberglass is an immensely versatile material due to its lightweight, inherent strength, weather-resistant finish and variety of surface textures. The development of fiber-reinforced plastic for commercial use was extensively researched in the 1930s. It was of particular interest to the aviation industry. A means of mass production of glass strands was accidentally discovered in 1932 when a researcher at Owens-Illinois directed a jet of compressed air at a stream of molten glass and produced fibers. After Owens merged with the Corning company in 1935, Owens Corning adapted the method to produce its patented "Fiberglas" (one "s"). A suitable resin for combining the "Fiberglas" with a plastic was developed in 1936 by DuPont. The first ancestor of modern polyester resins is Cyanamid's of 1942. Peroxide curing systems were used by then. During World War II, fiberglass was developed as a replacement for the molded plywood used in aircraft radomes (fiberglass being transparent to microwaves). Its first main civilian application was for the building of boats and sports car bodies, where it gained acceptance in the 1950s. Its use has broadened to the automotive and sport equipment sectors. In the production of some products, such as aircraft, carbon fiber is now used instead of fiberglass, which is stronger by volume and weight. Advanced manufacturing techniques such as pre-pregs and fiber rovings extend fiberglass's applications and the tensile strength possible with fiber-reinforced plastics. Fiberglass is also used in the telecommunications industry for shrouding antennas, due to its RF permeability and low signal attenuation properties. It may also be used to conceal other equipment where no signal permeability is required, such as equipment cabinets and steel support structures, due to the ease with which it can be molded and painted to blend with existing structures and surfaces. Other uses include sheet-form electrical insulators and structural components commonly found in power-industry products. Because of fiberglass's lightweight and durability, it is often used in protective equipment such as helmets. Many sports use fiber glass reinforced protective gear, such as goaltenders' and catchers' masks.
Epoxy sheet is also called insulating board, epoxy board, 3240 epoxy board. Epoxy resins generally refer to organic polymer compounds containing two or more epoxy groups in the molecule. Except for a few, their relative molecular mass is not high. The molecular structure of epoxy resin is characterized by the presence of active epoxy groups in the molecular chain, and the epoxy groups can be located at the end, middle or cyclic structure of the molecular chain. Due to the active epoxy groups in the molecular structure, they can be cross-linked with various types of curing agents to form insoluble and infusible polymers with a three-way network structure. The existence of polar hydroxyl and ether bonds inherent in the molecular chain of epoxy resin makes it have high adhesion to various substances. Epoxy resins have low shrinkage when cured and generate little internal stress, which also contributes to improved adhesion strength.
Fiberglass board alias: fiberglass insulation board, fiberglass board (FR-4), fiberglass composite board, etc. It is composed of fiberglass material and composite material with high heat resistance, and does not contain asbestos harmful to human body. It has high mechanical properties and dielectric properties, good heat resistance and moisture resistance, and good processability. For plastic molds, injection molds, machinery manufacturing, molding machines, drilling machines, injection molding machines, motors, PCB, ICT fixtures, table grinding pads. Injection mold molding usually requires: high temperature material and low temperature mold. In the same machine condition, the heat insulation method must be adopted.
Phenolic sheet is made of phenolic foam material, which is a polymer organic rigid aluminum foil foam product, which is foamed by thermosetting phenolic resin. Phenolic insulation boards are widely used in developed countries. According to statistics and literature records, 40% of fire-proof, thermal-insulation and sound-insulation materials in the United States are phenolic resins; the United Kingdom, Western Europe, and the Middle East stipulate that phenolic foam thermal insulation materials are preferred for new construction projects; Construction departments in France and Northern Europe believe that only phenolic foam insulation materials have good fire performance.

---

Tufting is a type of textile manufacturing in which a thread is inserted on a primary base. It is an ancient technique for making warm garments, especially mittens. After the knitting is done, short U-shaped loops of extra yarn are introduced through the fabric from the outside so that their ends point inwards (e.g., towards the hand inside the mitten). Usually, the tuft yarns form a regular array of "dots" on the outside, sometimes in a contrasting color (e.g., white on red). On the inside, the tuft yarns may be tied for security, although they need not be. The ends of the tuft yarns are then frayed, so that they will subsequently felt, creating a dense, insulating layer within the knitted garment. Tufting was first developed by carpet manufacturers in Dalton, Georgia. A tufted piece is completed in three steps: tufting, gluing, then backing and finishing. When tufting, the work is completed from the backside of the finished piece. A loop-pile machine sends yarn through the primary backing and leaves the loops uncut. A cut-pile machine produces plush or shaggy carpet by cutting the yarn as it comes through to the front of the piece. Tufted rugs can be made with coloured yarn to create a design, or plain yarn can be tufted and then dyed in a separate process.
Brush tufting machine can make a lot of tufted things like toothbrushes, cleaning brushes, etc. A toothbrush is an oral hygiene tool used to clean the teeth, gums, and tongue. It consists of a head of tightly clustered bristles, atop of which toothpaste can be applied, mounted on a handle which facilitates the cleaning of hard-to-reach areas of the mouth. They should be used in conjunction with something to clean between the teeth where the bristles of the toothbrush cannot reach - for example floss, tape or interdental brushes. They are available with different bristle textures, sizes, and forms. Most dentists recommend using a soft toothbrush since hard-bristled toothbrushes can damage tooth enamel and irritate the gums. Because many common and effective ingredients in toothpaste are harmful if swallowed in large doses and instead should be spat out, the act of brushing teeth is most often done at a sink within the kitchen or bathroom, where the brush may be rinsed off afterwards to remove any debris remaining and then dried to reduce conditions ideal for germ growth (and, if it is a wooden toothbrush, mold as well). Some toothbrushes have plant based handles, often bamboo. However, numerous others are made of cheap plastic; such brushes constitute a significant source of pollution. Over 1 billion toothbrushes are disposed of into landfills annually in the United States alone. Bristles are commonly made of nylon (which, while not biodegradable, as plastic is, may still be recycled) or bamboo viscose.
Cleaning brush is a tool for cleaning a toilet bowl, which belongs to a kind of household brush tufting machine. Generally the toilet brush is used with toilet cleaner or bleach. The cleaning brush can be used to clean the upper area of the toilet, around the bowl. However, it cannot be used to clean very far into the toilet's U-bend and should not be used to clean the toilet seat. In many cultures it is considered impolite to clean away biological debris without the use of chemical toilet cleaning products, as this can leave residue on the bristles. By contrast, others consider it impolite not to clean away biological debris immediately using the toilet brush. A typical cleaning brush consists of a hard bristled end, usually with a rounded shape and a long handle. Today cleaning brushes are commonly made of plastic, but were originally made of wood with pig bristles or from the hair of horses, oxen, squirrels and badgers. The brush is typically stored in a holder, but in some cases completely hidden in a tube. An electric toilet brush is a little different from a normal toilet brush. The bristles are fastened on the rotor of a motor which works similar to an electric tooth brush. The power supply is attached without any metal contact via electromagnetic induction. In recent years, there has been a general shift in design with a new emphasis on ergonomically designed brushes. Further design enhancements have included innovative holders that snap shut around the bristled end, thereby preventing the release of smells, germs and other unpleasantries. Further development of the traditional toilet brush focus on the risk of germ incubation within the brush holder. A cleaning brush has been patented which introduces a reservoir of anti-bacterial fluid, allowing the brush to be dipped and sanitized after each use.
Sanitation brushes belong to the manufacturing range of industrial brush tufting machines. They are disc brushes or wire disc brushes installed in municipal sanitation vehicles for street cleaning, and are the most representative type of sanitation brushes. The products include sweeper roller brush, sheet-type roller combination sweeper brush, roller sweeper brush, sweeper brush, square sweeper brush, round branch sweeper brush, sewage treatment brush, scrubber brush, computer car washing machine brushes, etc. The sanitation truck disc sweeping brush is made of high-strength plastic brush wire, which is used to clean the dirt on the ground; the roller brush is used for the washing machine. Materials available are PP brush wire, PA wire or steel wire.
Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or strip steel after crimping and welding, and the length is generally 6 meters. Welded steel pipes have simple production process, high production efficiency, many varieties and specifications, and less equipment investment, but the general strength is lower than that of seamless steel pipes. Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has been continuously improved, the varieties and specifications of welded steel pipes have been increasing, and more and more fields have replaced non-ferrous steel. Seam steel pipe. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of the weld. It is classified by production method: process classification - arc welded pipe, electric resistance welded pipe, (high frequency, low frequency) gas welded pipe, furnace welded pipe. Smaller diameter welded pipes use straight seam welding, and large diameter welded pipes are mostly spiral welded; according to the shape of the end of the steel pipe, they are divided into circular welded pipes and special-shaped (square, rectangular, etc.) welded pipes; according to different materials and uses, they are divided into mining fluids Conveying welded steel pipe, galvanized welded steel pipe for low-pressure fluid transportation, electric-welded steel pipe for belt conveyor rollers, etc. According to the specification and size table in the current national standard, sort by outer diameter * wall thickness from small to large.
The lap welding machine is mainly used for the production of stainless steel decoration, products, stainless steel pipes and carbon steel pipes for household appliances and can also produce various special-shaped tubes such as elliptical tubes, semi-circular tubes and plum blossom tubes. Shearing butt welding machine is an important equipment on the welded pipe production line. It is used for shearing and butt welding of the irregular parts of the head and tail of the strip to ensure the continuous production of the welded pipe machine unit. The forming and sizing machine is the main equipment in the welded pipe production line. It can continuously roll a certain specification of long steel strip into a tube and weld it into a tube. It can produce both round tubes and special-shaped tubes. This unit adopts the principle of roll forming, and the high-frequency welded pipe can continuously produce steel pipes of a certain specification. The heating method adopts induction welding, that is, a steel strip of a certain specification is fed into the machine, and the steel strip is coiled into a tube blank through the forming roller, and then used The skin effect and proximity effect of the high-frequency current make the current highly concentrated on the welding surface of the pipe edge, so that the pipe edge is quickly heated to the welding temperature and the welding is completed under the extrusion roller, and becomes the steel pipe of the required specification after cooling, sizing and rough straightening.

---

Pillow, a sleep tool. It is generally believed that pillows are the stuffing that people use to sleep comfortably. According to modern medical research, the spine of the human body is a straight line when viewed from the front, but a curve with four physiological curves when viewed from the side. In order to protect the normal physiological curvature of the neck and maintain normal physiological activities during sleep, pillows must be used when sleeping. Pillows generally consist of a pillow core and a pillowcase. Pillows consist of a filler material enclosed in a fabric cover or shell. Covers are made of cloth, such as silk, known as the pillow case or pillow slip. Some pillows have a fancier cover called a sham which is closed on all sides and usually has a slit in the back through which the pillow is placed. Rectangular standard bed pillow cases usually do not have zippers, but instead, have one side open all the time. Often, a zippered pillow protector is often placed around standard pillows with the case in turn covering the protector. Fillers are chosen on the basis of comfort, resilience, thermal properties, cost and also for medical and ethical reasons. The most common synthetic fillers are materials derived from polymer fibers, such as polyester and memory foam. Synthetic fillers in general are inexpensive and in the case of memory foam can retain their form longer. Natural fillers have been used since antiquity. The most common are feathers, down, wool, latex, cotton (particularly in India), and buckwheat. More exotic materials have also been used including straw , wood, or stone. Down is usually the softer filler and offer good insulation, but is more expensive due to its relative scarcity. Down has been known to be plucked from live geese, but there are already cruelty-free certifications for down products. In India, traditional pillows are made with kapok, the fluffy, glossy fruit-fibres of the trees Ceiba pentandra and Bombax ceiba.
Latex pillows are made of the sap of rubber trees, and it is impossible to make latex pillows made of 100% pure latex. The latex content of latex pillows on the market is only 80%-97%. Because pure latex cannot achieve coagulation and fluffy effects, it needs to be artificially fermented with safe materials. Latex pillow has the characteristics of natural environmental protection, non-polluting, non-toxic, anti-allergic and so on. Designed according to ergonomic principles, it can effectively promote sleep, effectively prevent snoring, and is suitable for asthma patients. The latex pillow can effectively reduce the static electricity between the human body and the fiber. The honeycomb structure has good air permeability, and quickly dissipates the heat generated by the human body. The most convenient thing about latex pillows is that they can be washed with water. Natural latex pillows are easy to clean by hand. As long as they are dried with a fan after dehydration, or dried in an oven at low temperature, they will never be deformed. They are easy to maintain, foldable, and easy to collect. It is the most comfortable choice for the pursuit of healthy sleep.
A pillow case is something that wraps the pillow under the pillow cover, like a cloth pocket. Pillowcases are an important part of modern pillows. Ancient people did not use pillowcases. They used pillow cores and pillow covers. Modern pillows come in three common one-piece styles, Oxford (with a flat edge) and trim. All three types of pillowcases have an inner seal that secures the pillow, so that there is no need to implement some reinforcement measures on both sides. Cotton, cotton polyester and rayon can all be used to sew pillowcases, but the most comfortable pillowcase material is pure cotton, which is breathable and hygroscopic, and does not irritate the skin. Modern people also like to use silk pillowcases, also known as silk pillowcases. Silk is a good thing and has many reputations such as fiber queen and soft gold. More than 97% of silk is composed of animal protein and rich in 18 kinds of amino acids necessary for the human body. Silk is said to clean and maintain the skin and increase the vitality of skin cells.
A blanket is a swath of soft cloth large enough either to cover or to enfold most of the user's body and thick enough to keep the body warm by trapping radiant body heat that otherwise would be lost through convection. Many types of blanket material, such as wool, are used because they are thicker and have more substantial fabric to them, but cotton can also be used for light blankets. Wool blankets are warmer and also relatively slow to burn compared to cotton. The most common types of blankets are woven acrylic, knitted polyester, mink, cotton, fleece and wool. Blankets also come with exotic crafting and exotic material such as crocheted afghan or a silk covering. The term blanket is often interchanged with comforter, quilt, and duvet , as they all have similar uses.
A towel is a piece of absorbent cloth or paper used for drying or wiping a surface. Towels draw moisture through direct contact. In households, several types of towels are used, such as hand towels, bath towels, and kitchen towels. Paper towels are provided in commercial or office bathrooms via a dispenser for users to dry their hands. They are also used for such duties such as wiping, cleaning, and drying. Bath towel is a cleaning product, which belongs to a type of towel. It is made of cotton fiber and is used to wipe the body, cover the body and keep warm after bathing. Bath towels are made of pure cotton yarn, and are divided into two categories: yarn-woven bath towels and thread-woven bath towels.
Sleep mask refers to a type of mask that is applied to the face and sleeps directly after basic skin care is done at night; it is usually cleaned in the next morning and the face can be washed normally. Generally, sleeping masks are gel or cream textures, which are like a layer of skin care products after applying them. Sleeping mask can also be understood as an upgraded version of cream, which is characterized by leave-on and can be wiped overnight. The principle of sleep mask skin care is: use a thick layer of essence dressing to block the contact between the facial skin and the air, block the evaporation of skin moisture, increase the humidity of the stratum corneum and soften the cuticle; The temperature of the epidermis increases to expand the pores, which is conducive to the smooth absorption of nutrients. After the skin temperature rises, the blood circulation is accelerated, so that the nutrients infiltrated into the skin are spread deeper and wider, and nutrients can be replenished quickly; The water that cannot be evaporated on the surface of the skin will remain in the epidermis. When the water in the epidermis is full, the skin will look smoother and tighter, the fine lines will become lighter, and the whiteness and brightness will be significantly improved.
A picnic blanket, also known as a multi-functional blanket, a cushion, etc., is a flannel (or acrylic) fabric with a waterproof bottom mat configured for a picnic. It can be rolled out at any time outdoors to provide a tidy space for a picnic or leisure. Because it can be folded and stored, it is very convenient to use. It can be used as a picnic bag or as an independent product for outdoor picnics, fitness, children's crawling, beach use, moisture-proof mats, tent bottom mats and other bedding needs. It adopts European and American popular integrated folding design, which can be easily folded back to its original shape along the crease on the seat cushion. There are various styles, such as handbag type, cylinder type, bag type, etc.
A mattress pad, mattress topper, or underpad is designed to lie atop a mattress. Made from a variety of materials such as wool, cotton, memory foam, feather or latex, its function is to provide an extra layer of comfort, especially when the Existing mattress is worn or uncomfortable. Physically, it is a thin mattress, usually 5–10 centimetres (2–4 in) thick. Stand-alone mattresses of this size exist (see futon, and Bed base#Floor beds; traditional European beds were made of a stack of mattresses of this size). But mattress toppers are usually sold for use on top of boxsprings (secured with straps or elasticated cloth corners). They are used to extend the life of the more-expensive boxspring, make a bed warmer or cooler (with airflow , or heat-conductive materials), make a firm bed softer, and for travel and dorms, as they are portable, especially if they are low-density.

---

The slewing drive is a gearbox that can safely hold radial and axial loads, as well as transmit a torque for rotating. The rotation can be in a single axis, or in multiple axes together. Slewing drives are made by manufacturing gearing, bearings, seals , housing, motor and other auxiliary components and assembling them into a finished gearbox. Slewing drives function with standard worm technology, in which the worm on the horizontal shaft acts as the driver for the gear. The rotation of the horizontal screw turns a gear about an axis perpendicular to the screw axis. This combination reduces the speed of the driven member and also multiplies its torque; increasing it proportionally as the speed decreases. The speed ratio of shafts depends upon the relation of the number of threads on the worm to the number of teeth in the worm wheel or gear. As technology has improved, more slewing drives are using hourglass worm technology, in which the worm is shaped to engage more teeth in the gear. This increased tooth engagement results in greater strength, efficiency and durability.
According to the variable speed transmission form of slewing drive, it can be divided into gear slewing drive and worm gear slewing drive, inheriting the respective characteristics of gear drive and worm gear drive. In terms of bearing capacity, the performance of the worm gear type is better than that of the tooth type, and when the enveloping worm drive is used, its bearing capacity, deformation resistance and transmission rigidity are further improved. However, the worm gear slewing drive is inferior to the gear slewing drive in terms of efficiency. According to the openness of the slewing drive transmission mechanism, the slewing drive can be divided into an open housing slewing drive and a closed slewing drive. Usually, the open structure is mostly used in applications where the environment is too harsh and the maintenance and maintenance cycle is short. The structure is more convenient for the inspection, maintenance and maintenance of the machine parts, and it is also more convenient to replace. On the other hand, where the environmental conditions do not change much and the environmental pollution level is below the medium level, the closed structure can provide a longer maintenance life cycle.
The slewing drive can be used in any occasion that requires full-circle rotation and requires variable speed. When it is necessary to realize the power transmission of larger torque, the transmission of higher precision motion or the selection of the mechanism that requires high compactness and integration. The slewing drives are the best solution. The more common applications are generally the full-circle rotary structure of engineering and construction machinery, as well as solar energy, wind energy and various long-term automatic tracking machinery. Due to the compact structure and short transmission chain, precision slewing drives are easier to achieve and easier to digitize. Therefore, it has many applications in the field of industrial robots.
Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with teeth projecting radially. Viewing the gear at 90 degrees from the shaft length (side on) the tooth faces are straight and aligned parallel to the axis of rotation. Looking down the length of the shaft, a tooth's cross section is usually not triangular. Instead of being straight (as in a triangle) the sides of the cross section have a curved form (usually involute and less commonly cycloidal) to achieve a constant drive ratio. Spur gears mesh together correctly only if fitted to parallel shafts. No axial thrust is created by the tooth loads. Spur gears are excellent at moderate speeds but tend to be noisy at high speeds. Spur gear can be classified into two pressure angles, 20° being the current industry standard and 14½° being the former (often found in older equipment). Spur gear teeth are manufactured as either involute profile or cycloidal profile. When two gears are in mesh it is possible that an involute portion of one will contact a non-involute portion of the other gear. This phenomenon is known as "interference" and occurs when the number of teeth on the smaller of the two meshing gears is less than a required minimum . Undercutting (cutting the tooth narrower closer to its base) is sometimes used to avoid interference but is usually not suitable because the decreased thickness leaves the tooth weaker at its base. In this situation, corrected gears are used. In corrected gears the cutter rack is shifted upwards or downwards. Spur gears can be classified into two main categories: External and Internal. Gears with teeth on the outside of the cylinder are known as "external gears". Gears with teeth on the internal side of the cylinder are known as "internal gears". An external gear can mesh with an external gear or an internal gear. When two external gears mesh together they rotate in the opposite directions. An internal gear can only mesh with an external gear and the gears rotate in the same direction. Due to the close positioning of shafts, internal gear assemblies are more compact than external gear assemblies. The spur gear slewing drive type is the more common one.
Active trackers use motors and gear trains to perform solar tracking. They can use microprocessors and sensors, date and time-based algorithms, or a combination of both to detect the position of the sun. In order to control and manage the movement of these massive structures special slewing drives are designed and rigorously tested. The technologies used to direct the tracker are constantly evolving and recent developments at Google and Eternegy have included the use of wire-ropes and winches to replace some of the more costly and more fragile components. Counter rotating slewing drives sandwiching a fixed angle support can be applied to create a "multi-axis" tracking method which eliminates rotation relative to longitudinal alignment. This method if placed on a column or pillar will generate more electricity than fixed PV and its PV array will never rotate into a parking lot drive lane. It will also allow for maximum solar generation in virtually any parking lot lane/row orientation, including circular or curvilinear. Active two-axis trackers are also used to orient heliostats - movable mirrors that reflect sunlight toward the absorber of a central power station. As each mirror in a large field will have an individual orientation these are controlled programmatically through a central computer system, which also allows the system to be shut down when necessary. Light-sensing trackers typically have two or more photosensors, such as photodiodes, configured differentially so that they output a null when receiving the same light flux. Mechanically, they should be omnidirectional (i.e. flat) and are aimed 90 degrees apart. This will cause the steepest part of their cosine transfer functions to balance at the steepest part, which translates into maximum sensitivity. For more information about controllers see active daylighting. Since the motors consume energy, one wants to use them only as necessary. So instead of a continuous motion, the heliostat is moved in discrete steps. Also, if the light is below some threshold there would not be enough power generated to warrant reorientation. This is also true when there is not enough difference in light level from one direction to another, such as when clouds are passing overhead. Consideration must be made to keep the tracker from wasting energy during cloudy periods. And also there are other solar product spare parts.

---

A T shirt, or tee shirt, is a style of fabric shirt named after the T shape of its body and sleeves. Traditionally, it has short sleeves and a round neckline, known as a crew neck, which lacks a collar. T-shirts are generally made of a stretchy, light, and inexpensive fabric and are easy to clean. The T-shirt evolved from undergarments used in the 19th century and, in the mid-20th century, transitioned from undergarment to general-use casual clothing. They are typically made of cotton textile in a stockinette or jersey knit, which has a distinctively pliable texture compared to shirts made of woven cloth. Some modern versions have a body made from a continuously knitted tube, produced on a circular knitting machine, such that the torso has no side seams. The manufacture of T-shirts has become highly automated and may include cutting fabric with a laser or a water jet. T-shirts are inexpensive to produce and are often part of fast fashion, leading to outsized sales of T-shirts compared to other attire. For example, two billion T-shirts are sold per year in the United States, or the average person from Sweden buys nine T-shirts a year. Production processes vary but can be environmentally intensive, and include the environmental impact caused by their materials, such as cotton which is both pesticide and water intensive.
A hoodie (in some cases it is also spelled hoody and alternatively known as a hooded sweatshirt) is a sweatshirt with a hood. Hoodies often include a muff sewn onto the lower front, and (usually) a drawstring to adjust the hood opening. It covers most of the head and neck and sometimes the face. Hoodies may be worn for protection against the environment (cold weather, rain, etc.) Hoodies have become a mainstream fashion in the U.S., transcending the clothing item's original utilitarian purpose, similar to jeans. This clothing item has found its way into a variety of styles, even so far as to be worn under a suit jacket. Hoodies with zippers are generally referred to as zip-up hoodies, while a hoodie without a zipper may be described as a pullover hoodie. Throughout the U.S., it is common for teenagers and young adults to wear sweatshirts—with or without hoods—that display their respective school names or mascots across the chest, either as part of a uniform or personal preference. The hooded sweatshirt is a utilitarian garment that originated in the 1930s for workers in cold New York warehouses and thus have been around for over 80 years. In the 70s and 80s, hoodies were adopted by hip hop culture as a symbol of what one reporter termed "cool anonymity and vague menace" When the garment was depicted in FBI composite drawings of Unabomber Ted Kaczynski, the hoodie became linked to "seedy threatening criminality," thereby further asserting its non-mainstream symbolism.
Sweatpants are a casual variety of soft trousers intended for comfort or athletic purposes, although they are now worn in many different situations. In the United Kingdom, Ireland, Australia, New Zealand, and South Africa they are known as tracksuit bottoms. In Australia and New Zealand, they are also commonly known as track pants, trackies or tracky daks. Sweatpants are usually made from stretchy knitted jersey fabrics of differing weights, including single jersey, double jersey, fleeceback jersey, and loopback jersey (terry). They are a pull-on style pants and often have a flexible elasticated waistband with a drawstring closure. They may or may not have a fly and pockets. Some sweatpants can also feature elasticized cuffs at the hem of the leg. Sweatpants are traditionally ash gray in color but are now available in most colors. Traditionally quite "baggy" and loose, sweatpants are now also available in more form-fitting shapes; moreover, they have flexibility and comfort.
A sweatshirt is a long-sleeved pullover shirt fashioned out of thick, usually cotton cloth material. Sweatshirts are almost exclusively casual attire and hence not as dressy as some sweaters. Sweatshirts may or may not have a hood. A sweatshirt with a hood is now usually referred to as a hoodie, although more formal media still use the term "hooded sweatshirt". The sweatshirt's potential as a portable advertising tool was discovered in the 1960s when U.S. universities began printing their names on the medium. For students and parents alike, university names on sweatshirts became the preferred casual attire for exhibiting school pride. The sweatshirt, along with the T-shirt, provided a cheap and effective way of disseminating information on a mass scale. The T-shirt slogan fad of the seventies inevitably translated to sweatshirts. Due to the relative simplicity of customization and the power of clever graphics combined with catchphrases, sweatshirts became a vehicle for personal expression for both the designer and the person wearing them. In Australia, the sweatshirt is referred to as a 'Sloppy Joe'.
Yoga pants/gym Leggings are high-denier hosiery reaching from ankle to waist, originally designed for yoga as exercise and first sold in 1998 by Lululemon, a company founded for that purpose. They were initially made of a mix of nylon and Lycra; more specialised fabrics have been introduced to provide moisture-wicking, compression, and odour reduction. The market has increased both through the popularity of yoga and because many women wear yoga pants as casual everyday dress. This is part of a long-term "athleisure" trend of increasing informality in dress, threatening sales of traditional jeans. In the United States, the wearing of yoga pants other than for exercise has aroused controversy, both for school use and when worn by women. Global sales of yoga clothing have all the same grown rapidly, reaching some $31 billion by 2018. Styles include the traditional boot-cut and flared yoga pants with a flat waistband. Basic yoga pants are black, tight-fitted, boot-cut, flared, and reversible; they are made of a four-way stretch fabric, with a flat elastic waistband at the top. They provide flexibility and comfort, wicking moisture away from the body and helping to keep the wearer cool and comfortable. They may be made from blends of cotton, Lycra spandex, nylon, polyester, wool, or similar light and stretchy synthetic material giving the pants a soft, smooth finish.
A sleeveless shirt is a shirt manufactured without sleeves, or whose sleeves have been cut off. Depending on the style, they can be worn as undershirts, worn by athletes in sports such as track and field and triathlon, or as casual wear. In the United States and Canada, any casual sleeveless shirt can be called tank top or tank shirt, with several specific varieties. It is named after tank suits, one-piece bathing suits of the 1920s worn in tanks or swimming pools. The upper garment is worn commonly by both men and women. The build of a tank top/singlet is simple: the neck and armholes are often reinforced for durability. One usually has large armholes and neck holes and a neckline that can reach down as far as the bottom of the chest. (Women's tank tops have smaller holes, to conceal their breasts). They are also sometimes made long to make tucking into pants easier. In almost all cases, they are buttonless, collarless, and pocketless. A sleeveless T-shirt, also called a muscle shirt, is the same design as a T-shirt, but without sleeves. Some sleeveless T-shirts, which possess smaller, narrower arm holes, can be worn by both women and men, usually with sports bras underneath for women. They are often worn during athletic activities or as casual wear during warmer weather. They are colloquially known as shooter shirts in the southern United States. They were quite popular in the 1980s and were commonly associated with surfers and bodybuilders (hence the name "muscle" shirt) and often bore the names and logos of gyms. Such shirts without logos are now more commonly worn as casual wear.
Nursing bras are a type of nursing wear. A nursing bra is a specialized brassiere that provides additional support to women who are lactating and permits comfortable breastfeeding without the need to remove the bra. This is accomplished by specially designed bra cups that include flaps which can be opened with one hand to expose the nipple. The flap is usually held closed with a simple clasp or hook. There are an increasing variety of nursing bras designs, including softcup, underwire, seamless, and lounging styles. Some nursing bras can also serve as a sports bra, allowing a nursing mother to exercise more easily. Some outerwear like tank tops and T-shirts have nursing bras that are built into the garment, and there are also padded and plus-size nursing bras. Some experts advise against wearing an underwire nursing bra because they can restrict the flow of milk and cause mastitis. Most nursing bras have traditionally been white , but manufacturers now offer an increasing selection of colors and styles, including brown, teal, floral, and floral animal prints, and some are accessorized with lace and ribbon.

---

In automatic control, a regulator is a device which has the function of maintaining a designated characteristic. It performs the activity of managing or maintaining a range of values in a machine. The measurable property of a device is managed closely by specified conditions or an advance set value; or it can be a variable according to a predetermined arrangement scheme. It can be used generally to connote any set of various controls or devices for regulating or controlling items or objects. Regulators can be designed to control anything from gases or fluids, to light or electricity. Speed can be regulated by electronic, mechanical, or electro-mechanical means. Such instances include: Electronic regulators as used in modern railway sets where the voltage is raised or lowered to control the speed of the engine; Mechanical systems such as valves as used in fluid control systems. Purely mechanical pre-automotive systems included such designs as the Watt centrifugal governor whereas modern systems may have electronic fluid speed sensing components directing solenoids to set the valve to the desired rate.
Designed in 1835, the gas regulator's concept is easy, and its impact has been long-lasting. There are various types of regulators, but their function is the same: to use a valve system to control natural gas or propane pressure or other gas flow. Common appliances that use regulators include gas stoves, propane grills, or oxy-fuel bottles for welding. Each type of regulator's components consists of a set spring attached to a rod that runs down from a set screw through a diaphragm into the valve. There are three primary operating components working together to regulate the pressure within the valve. The loading mechanism determines the delivery pressure. Most often, it is a spring. The sensing element, or diaphragm, senses the force against the spring. Finally, the control element accomplishes the reduction of the inlet pressure through to the outlet pressure. Gas enters the regulator's chamber, putting pressure on the diaphragm. The diaphragm then moves upward as controlled by the set spring. This allows a specific flow of fuel from the source to the appliance or device. Adjusting the control knob determines the rate of flow and the pressure. Turning clockwise will push the diaphragm down and allow more gas to come into the valve. Turn counter-clockwise to reduce the amount of fuel and pressure.
Liquefied petroleum gas (LPG, LP gas, or condensate) is a fuel gas made of petrol which contains a flammable mixture of hydrocarbon gases, most commonly propane, butane, and propylene. However, the latter two typically compose 5% or less of the mixture. LPG is used as a fuel gas in heating appliances, cooking equipment, and vehicles. It is increasingly used as an aerosol propellant and a refrigerant, replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. When specifically used as a vehicle fuel, it is often referred to as autogas. Varieties of LPG that are bought and sold include mixes that are mostly propane (C3H8), mostly butane (C4H10), and, most commonly, mixes including both propane and butane. In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane. In the United States, mainly two grades of LPG are sold: commercial propane and HD-5. These specifications are published by the Gas Processors Association (GPA) and the American Society of Testing and Materials. Propane/butane blends are also listed in these specifications. Propylene, butylenes and various other hydrocarbons are usually also present in small concentrations such as C2H6, CH4, and C3H8. HD-5 limits the amount of propylene that can be placed in LPG to 5% and is utilized as an autogas specification. A powerful odorant, ethanethiol, is added so that leaks can be detected easily. The internationally recognized European Standard is EN 589. In the United States, tetrahydrothiophene (thiophane) or amyl mercaptan are also approved odorants, although neither is currently being utilized. An LPG regulator is a device that maintains a stable downstream pressure regardless of changes in gas flow and upstream pressure. Among them, the LPG jumbo regulator and the LPG quick-on regulator are typical representatives.
A hose is a flexible hollow tube designed to carry fluids from one location to another. Hoses are also sometimes called pipes (the word pipe usually refers to a rigid tube, whereas a hose is usually a flexible one), or more generally tubing. The shape of a hose is usually cylindrical (having a circular cross section). Hose design is based on a combination of application and performance. Common factors are size, pressure rating, weight, length, straight hose or coilhose, and chemical compatibility. Applications mostly use nylon, polyurethane, polyethylene, PVC, or synthetic or natural rubbers, based on the environment and pressure rating needed. In recent years, hoses can also be manufactured from special grades of polyethylene (LDPE and especially LLDPE). Other hose materials include PTFE (Teflon), stainless steel, and other metals. Dredge rubber hoses have a long story, which features high strength and flexibility. A flexible dredging hose widely used in dredgers to convey silt or gravel. It is resistant to abrasion and wear to ensure long service life. Types of flexible dredge hose include the floating rubber hose, discharge hose, suction hose, armored hose and ceramic hose. To achieve a better pressure resistance, hoses can be reinforced with fibers or a steel cord. Commonly used reinforcement methods are braiding, spiraling, knitting and wrapping of fabric plies. The reinforcement increases the pressure resistance but also the stiffness. To obtain flexibility, corrugations or bellows are used. Usually these corrugated internal or helical reinforcement rings are applied to maintain these corrugated or bellowed structures under pressure.
The gas hose includes a pipe joint, the pipe joint is composed of a pipe body and a steel sleeve fastened to one end of the pipe body, the pipe body has a through hole, and the one end of the pipe body is formed with a an annular coupling groove into which the hose is inserted, the axial depth of the annular coupling groove is greater than the length of the steel sleeve, and a part of the inner surface of the annular coupling groove is a tapered surface, a step is formed where the inner end of the tapered surface abuts another part of the inner surface of the annular coupling groove. The structure avoids the phenomenon that when the pipe joint is matched with the hose, the hose is inserted too deeply into the pipe joint, which causes deformation of the end of the pipe joint, which is beneficial to the smooth flow of gas and has high safety. A circular arc transition is adopted at the junction between the outer surface and the inner surface of the annular coupling groove to prevent stress concentration.
A gas stove is a stove that is fuelled by combustible gas such as syngas, natural gas, propane, butane, liquefied petroleum gas or other flammable gas. Before the advent of gas, cooking stoves relied on solid fuels such as coal or wood. The first gas stoves were developed in the 1820s and a gas stove factory was established in England in 1836. This new cooking technology had the advantage of being easily adjustable and could be turned off when not in use. The gas stove, however, did not become a commercial success until the 1880s, by which time supplies of piped gas were available in cities and large towns in Britain. The stoves became widespread on the European Continent and in the United States in the early 20th century. Gas stoves became more common when the oven was integrated into the base and the size was reduced to better fit in with the rest of the kitchen furniture. By the 1910s, producers started to enamel their gas stoves for easier cleaning. Ignition of the gas was originally by match and this was followed by the more convenient pilot light. This had the disadvantage of continually consuming gas. The oven still needed to be lit by match and accidentally turning on the gas without igniting it could lead to an explosion. To prevent these types of accidents, oven manufacturers developed and installed a safety valve called a flame failure device for gas hobs (cooktops) and ovens. Most modern gas stoves have electronic ignition, automatic timers for the oven and extractor hoods to remove fumes. Gas stoves are a significant source of indoor air pollution, and require good ventilation to maintain acceptable air quality.

---

Galvanized steel pipes are divided into cold galvanized steel pipes and hot-dip galvanized steel pipes. Cold galvanized steel pipes have been banned. In the 1960s and 1970s, developed countries in the world began to develop new types of pipes and gradually banned galvanized pipes. Four ministries and commissions including the Ministry of Construction of China have also issued a document stating that galvanized pipes are prohibited from being used as water supply pipes since 2000. Galvanized pipes are rarely used for cold water pipes in newly built communities, and galvanized pipes are used for hot water pipes in some communities. Hot-dip galvanized steel pipes have a wide range of applications in fire protection, power and highways. Galvanized steel pipe is a welded steel pipe with a hot-dip galvanized or electro-galvanized layer on the surface. Galvanizing can increase the corrosion resistance of steel pipes and prolong the service life. Galvanized pipes are widely used. In addition to being used as pipeline pipes for general low-pressure fluids such as water, gas, and oil, they are also used as oil well pipes and oil pipes in the petroleum industry, especially in offshore oil fields, and oil heaters and condensers in chemical coking equipment. Pipes for coolers, coal distillation washing oil exchangers, and pipes for trestle piles, supporting frames for mine tunnels, etc.
Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around 450 °C ( 842 °F). When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that protects the steel underneath from further corrosion in many circumstances. Galvanized steel is widely used in applications where corrosion resistance is needed without the cost of stainless steel, and is considered superior in terms of cost and life-cycle. It can be identified by the crystallization patterning on the surface (often called a "spangle"). Galvanized steel can be welded; however, one must exercise caution around the resulting toxic zinc fumes. Galvanized fumes are released when the galvanized metal reaches a certain temperature. This temperature varies by the galvanization process used. In long-term, continuous exposure, the recommended maximum temperature for hot-dip galvanized steel is 200 °C (392 °F), according to the American Galvanizers Association. The use of galvanized steel at temperatures above this will result in peeling of the zinc at the inter metallic layer. Electrogalvanized sheet steel is often used in automotive manufacturing to enhance the corrosion performance of exterior body panels; this is, however, a completely different process which tends to achieve lower coating thicknesses of zinc.
Hot dipped galvanized steel pipes are made by reacting the molten metal with the iron matrix to produce an alloy layer, so that the matrix and the coating are combined. Hot-dip galvanizing is to first pickle the steel pipe to remove iron oxide on the surface of the steel pipe. After pickling, it is cleaned in a tank of ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to a hot dip plating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. The hot-dip galvanized steel pipe substrate undergoes complex physical and chemical reactions with the molten bath to form a corrosion-resistant zinc-iron alloy layer with a tight structure. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix, so it has strong corrosion resistance. Hot dipped galvanized steel pipes are widely used in construction, machinery, coal mines, chemicals, electric power, railway vehicles, automobile industry, highways, bridges, containers, sports facilities, agricultural machinery, petroleum machinery, prospecting machinery, greenhouse construction and other manufacturing industries.
Stainless steel pipe is a kind of hollow long round steel, which is mainly used in industrial transportation pipelines and mechanical structural components such as petroleum, chemical industry, medical treatment, food, light industry, mechanical instrument and so on. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures. It is also commonly used as furniture and kitchenware. There are various connection methods for stainless steel pipes. The common types of pipe fittings are compression type, compression type, union type, push type, push thread type, socket welding type, union flange connection, welding type and welding and traditional connection. Combined derivative series connection method. These connection methods have different application scopes according to their different principles, but most of them are easy to install, firm and reliable. The sealing ring or gasket material used for the connection is mostly made of silicone rubber, nitrile rubber and EPDM rubber that meet the requirements of national standards, which relieves users from worries.
Scaffolding, also called scaffold or staging, is a temporary structure used to support a work crew and materials to aid in the construction, maintenance and repair of buildings, bridges and all other man-made structures. Scaffolds are widely used on site to get access to heights and areas that would be otherwise hard to get to. Unsafe scaffolding has the potential to result in death or serious injury. Scaffolding is also used in adapted forms for formwork and shoring, grandstand seating, concert stages, access/viewing towers, exhibition stands, ski ramps, half pipes and art projects. There are five main types of scaffolding used worldwide today. These are tube and coupler (fitting) components, prefabricated modular system scaffold components, H-frame / façade modular system scaffolds, timber scaffolds and bamboo scaffolds (particularly in China and India). Each type is made from several components which often include: A base jack or plate which is a load-bearing base for the scaffold; The standard, the upright component with connector joins; The ledger, a horizontal brace; The transom, a horizontal cross-section load-bearing component which holds the batten, board, or decking unit; Brace diagonal and/or cross section bracing component; Batten or board decking component used to make the working platform; Coupler, a fitting used to join components together; Scaffold tie, used to tie in the scaffold to structures; Brackets, used to extend the width of working platforms.
Steel coil, also known as coil steel. The steel is hot-pressed and cold-pressed into rolls. In order to facilitate storage and transportation, it is convenient to carry out various processing (such as processing into steel plates, steel strips, etc.). Formed coils are mainly hot-rolled coils and cold-rolled coils. Hot rolled coil is the processed product before the recrystallization of the steel billet. Cold rolled coil is the subsequent processing of hot rolled coil. The general weight of the steel coil is about 15-30T. my country's hot rolling production capacity has been continuously expanded. There are already dozens of hot rolling production lines, and some projects are about to start construction or put into production.
The hot rolled steel plate is made of continuous casting slab or blooming slab as raw material, heated in a walking furnace, descaled by high-pressure water, and then sent to the rough rolling mill. Rolling, laminar cooling (computer-controlled cooling rate) and coiling by coiler after finishing rolling. The head and tail of the straight hair curler are often tongue-shaped and fish-tail-shaped, with poor thickness and width accuracy, and the edges often have defects such as wave shape, folded edge, and tower shape. The coil weight is heavier, and the inner diameter of the steel coil is 760mm. It has good processing performance and compressive strength, and is used to produce high-pressure gas pressure vessels filled with LPG, acetylene gas and various gases with an inner volume of less than 500L.

---

The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled at the anus as feces. Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. Most animals have a "through-gut" or complete digestive tract. Exceptions are more primitive ones: sponges have small pores (ostia) throughout their body for digestion and a larger dorsal pore (osculum) for excretion, comb jellies have both a ventral mouth and dorsal anal pores, while cnidarians and acoels have a single pore for both digestion and excretion. The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts. The GI tract includes all structures between the mouth and the anus, forming a continuous passageway that includes the main organs of digestion, namely, the stomach, small intestine, and large intestine. The complete human digestive system is made up of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver and gallbladder). The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment. The whole human GI tract is about nine metres (30 feet) long at autopsy. It is considerably shorter in the living body because the intestines, which are tubes of smooth muscle tissue, maintain constant muscle tone in a halfway-tense state but can relax in spots to allow for local distention and peristalsis.
Endoscopic submucosal dissection (ESD) is an advanced surgical procedure using endoscopy to remove gastrointestinal tumors that have not entered the muscle layer. ESD may be done in the esophagus, stomach or colon. Application of endoscopic resection (ER) to gastrointestinal (GI) neoplasms is limited to lesions with no risk of nodal metastasis. Either polypectomy or endoscopic mucosal resection (EMR) is beneficial for patients because of its low level of invasiveness. However, to ensure the curative potential of these treatment modalities, accurate histopathologic assessment of the resected specimens is essential because the depth of invasion and lymphovascular infiltration of the tumor is associated with considerable risk for lymph node metastasis. For accurate assessment of the appropriateness of the therapy, en bloc resection is more desirable than piecemeal resection. For a reliable en bloc resection of GI neoplasms, a new method of ER called endoscopic submucosal dissection (ESD) has been developed. The ESD technique has developed from one of the EMR techniques, namely endoscopic resection after local injection of a solution of hypertonic saline-epinephrine (ERHSE). Initially, the ESD technique was called by various names such as cutting EMR, exfoliating EMR, EMR with circumferential incision etc. However, a new name was proposed to this technique in 2003, as a treatment positioned between EMR and laparoscopic surgery, since this technique is innovative and enables complete resection of neoplasms that were impossible to resect en bloc by EMR.
A speculum is a medical tool for investigating body orifices, with a form dependent on the orifice for which it is designed. In old texts, the speculum may also be referred to as a diopter or dioptra. Like an endoscope, a speculum allows a view inside the body; endoscopes, however, tend to have optics while a speculum is intended for direct vision. The best-known speculum is the bivalved vaginal speculum; the two blades are hinged and are "closed" when the speculum is inserted to facilitate its entry and "opened" in its final position where they can be arrested by a screw mechanism, so that the operator is freed from keeping the blades apart. A cylindrical-shaped speculum, introduced in 2001, the dilating vaginal speculum (also known as the Veda-scope) invented by Clemens van der Weegen, inflates the vagina with filtered air. The device has two main functions: a) to take a normal Pap smear with a cervical brush or a cytology brush; and b) as an internal colposcope so that the operator can pivot the Veda-scope to view any part of the vagina barrel and cervix facilitated by an internal light source that can illuminate the vaginal wall and cervix with multi-coloured light filters, which can detect pre-cancerous cells with the aid of acetic acid solution and iodine solution. It also has a facility to attach a digital camera for viewing and recording.
Percutaneous transhepatic cholangiography, percutaneous hepatic cholangiogram (PTHC) is a radiological technique used to visualize the anatomy of the biliary tract. A contrast medium is injected into a bile duct in the liver, after which X-rays are taken. It allows access to the biliary tree in cases where endoscopic retrograde cholangiopancreatography has been unsuccessful. Initially reported in 1937, the procedure became popular in 1952. PTBD is done one to two weeks before the procedure to reduce oedema of the biliary ducts and sphincter of Oddi oedema. Either high osmolar contrast medium or low osmolar contrast medium can be used (with concentration of 150 mg/ml). Low density contrast medium is used to prevent obscuring of the calculus. Antibiotic prophylaxis and pre-medication is given one hour before the procedure. Painkillers is given during the procedure. The subject lie down in supine position on the table. PTHC is performed if biliary drainage catheter is not in-situ. The drainage catheter is then removed over the guidewire and sheath is inserted into the ducts (7 to 8 French size). Contrast is then injected through the sheath to identify any stones or strictures. If a stricture is identified, put in biliary manipulation catheter with guidewire measuring 0.035 inches and commence balloon dilatation (with balloon sizes of 8, 10, and 12 mm). Using the balloon catheter, the stones are pushed into the duodenum. If the stones are difficult to push, Dormier basket is used to push them into the duodenum. The basket is removed and guidewire is inserted back into the sheath. The sheath is then removed and biliary drainage catheter is inserted back through the guidewire. Contrast is then injected intermittently through the drainage catheter to follow-up on the position of the stones.
Endoscopic retrograde cholangiopancreatography (ERCP) is a technique that combines the use of endoscopy and fluoroscopy to diagnose and treat certain problems of the biliary or pancreatic ductal systems. It is primarily performed by highly skilled and specialty trained gastroenterologists. Through the endoscope, the physician can see the inside of the stomach and duodenum, and inject a contrast medium into the ducts in the biliary tree and pancreas so they can be seen on radiographs. ERCP is used primarily to diagnose and treat conditions of the bile ducts and main pancreatic duct, including gallstones, inflammatory strictures (scars), leaks (from trauma and surgery), and cancer. ERCP can be performed for diagnostic and therapeutic reasons, although the development of safer and relatively non-invasive investigations such as magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasound has meant that ERCP is now rarely performed without therapeutic intent.
A snare is a device used to ligate blood vessels, polyps or other duct structures by tightening a slip knot made with absorbable thread or synthetic thread with a nylon rod. It is easy to operate and has been used as a polypectomy snare in a variety of laparoscopic abdominal surgeries. Snare has the advantages of safety, convenience and economy. (1) Safety: The snare is made of absorbable thread, which has little response to human tissue after being placed in the body; the operation is reversible, and the ligation position can be directly cut off; the cutting force on the tissue is smaller than that of the titanium clip, which is not easy to occur. (2) Convenience: Compared with suturing and ligating tissue under laparoscopy, the operation of using snare ligation is simple, no other special instruments are required, and the operation time can be shortened, especially for beginners, which is easy to master and use; (3) Economical: The snare is inexpensive, and its application can correspondingly reduce the consumption of the expensive endoscopic incision closure device (Endo-GIA), which reduces medical expenses to a certain extent.

---

High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device. HDMI is a digital replacement for analog video standards. HDMI implements the EIA/CEA-861 standards, which define video formats and waveforms, transport of compressed and uncompressed LPCM audio, auxiliary data, and implementations of the VESA EDID.  CEA-861 signals carried by HDMI are electrically compatible with the CEA-861 signals used by the Digital Visual Interface (DVI). No signal conversion is necessary, nor is there a loss of video quality when a DVI-to-HDMI adapter is used. The Consumer Electronics Control (CEC) capability allows HDMI devices to control each other when necessary and allows the user to operate multiple devices with one handheld remote control device. An electrical cable is an assembly of one or more wires running side by side or bundled, which is used to carry electric current. One or more electrical cables and their corresponding connectors may be formed into a cable assembly, which is not necessarily suitable for connecting two devices but can be a partial product (e.g. to be soldered onto a printed circuit board with a connector mounted to the housing). Cable assemblies can also take the form of a cable tree or cable harness, used to connect many terminals together.
AOC refers to a communication cable that needs to use external energy to convert electrical signals into optical signals, or convert optical signals into electrical signals in the communication process. The optical transceivers of the two sections of the optical cable provide photoelectric conversion and optical transmission functions. It consists of optoelectronic devices (two optical transceivers and cable jumpers). Active optical cables are mainly used in data centers, high-performance computers, large-capacity storage devices and other equipment for high-speed and reliable interconnection and transmission equipment. AOC application is an electrical interface that meets the requirements of industrial standards. It uses the internal electrical-optical-electrical conversion of the optical cable to enable the optical cable to perform efficient and stable data transmission. The maximum signal transmission distance that an HDMI AOC cable can achieve depends on the entire system: the performance of the source device, the performance of the display device, the data transfer rate of the signal, the performance and length of the cable itself. It can also be divided into HDMI AOC cable 4K, HDMI AOC cable 8K and so on. In the digital age, we use data rate to describe the amount of data in bits per second. The length of the HDMI cable is closely related to the maximum data transfer rate. If the distance is too long, the signal received by the HDMI device will have no image, dropped frames, snow, or no sound. The shorter the HDMI cable, the higher the maximum data transfer rate that can be achieved. For example, the data transmission rate of an HDMI cable with a length of 2m is 19Gb/s, which can meet the video transmission of 1080p, 120Hz, and 48bit color depth. However, if the length reaches 6 meters, the data transmission rate will drop to 10Gb/s, which can only meet the video transmission of 1080p, 120Hz, and 24bit color depth. So, as the length of the cable increases, the data transfer rate also decreases.
The USB cable is used for the connection and communication between the computer and external devices, and can also be used for the charging of the mobile phone and the connection with the outside, that is, for data transmission and charging. USB is the most widely used external bus standard in the PC field. It is used to standardize the connection and communication between the computer and external devices. The USB interface supports the plug-and-play and hot-swap functions of the device. With the rapid development of computer hardware, the application of USB has increased the speed of data transmission between external devices. The greatest benefit to users of increased speed is that users can use more efficient external devices. For example, it only takes about 0.1 seconds to scan a 4M picture with a USB 2.0 scanner, and the work efficiency is greatly improved. According to different interfaces and data lines of USB, supported devices: mouse, keyboard, printer, scanner, camera, flash disk, MP3 player, mobile phone, digital camera, mobile hard disk, external optical floppy drive, USB network card, ADSL modem, cable modem and other electronic products.
USB Type-C is a USB interface shape standard, which has a smaller volume than Type-A and Type-B, and can be applied to both PC (host device) and external device (eg mobile phone) interface type. USB Type-C has 4 pairs of TX/RX split lines, 2 pairs of USBD+/D-, a pair of SBU, 2 CCs, and 4 VBUS and 4 ground wires. USB 3.1 Type C cables are considered full-featured USB-C cables. They are electronically marked cables that contain a chip with an ID function based on the configuration channel and vendor-defined messages (VDM) from the USB Power Delivery 2.0 specification. Cable length should be ≤2 m for Gen 1 or ≤1 m for Gen 2. The electronic ID chip provides information about product/vendor, cable connectors, USB signalling protocol (2.0, Gen 1, Gen 2), passive/active construction, use of VCONN power, available VBUS current, latency, RX/TX directionality, SOP controller mode, and hardware/firmware version. USB-C cables that do not have shielded SuperSpeed pairs, sideband use pins, or additional wires for power lines can have increased cable length, up to 4 m. These USB-C cables only support 2.0 speeds and do not support alternate modes. All USB-C cables must be able to carry a minimum of 3 A current (at 20 V, 60 W) but can also carry high-power 5 A current (at 20 V, 100 W). USB-C to USB-C cables supporting 5A current must contain e-marker chips (also marketed as E-Mark chips) programmed to identify the cable and its current capabilities. USB Charging ports should also be clearly marked with capable power wattage.
Thunderbolt is the brand name of a hardware interface for the connection of external peripherals to a computer. It has been developed by Intel, in collaboration with Apple. It was initially marketed under the name Light Peak, and first sold as part of an end-user product on 24 February 2011. Thunderbolt combines PCI Express (PCIe) and DisplayPort (DP) into two serial signals, and additionally provides DC power, all in one cable. Up to six peripherals may be supported by one connector through various topologies. Thunderbolt 1 and 2 use the same connector as Mini DisplayPort (MDP), whereas Thunderbolt 3 and 4 reuse the USB-C connector from USB. Several other brands have released copper Thunderbolt cables, with some going up to the maximum 3 metres (9.8 feet) allowable for copper Thunderbolt 1 & 2 cables. Initially, most devices did not come with an included Thunderbolt cable to keep selling cost lower, hence the mass usage of Apple's cables or third-party cables, especially if a user wanted 3 m (9.8 ft) length, but most devices eventually began including some length of copper Thunderbolt cable with the product. With the introduction of Thunderbolt 3, Intel announced that otherwise-standard passive USB-C cables would be able to connect Thunderbolt devices at lower speeds than full active Thunderbolt cables, but still faster than USB 3.1. This allows for cheaper connections to new Thunderbolt devices, with inexpensive USB-C cables costing significantly less than active Thunderbolt cables. Released from mid-2016, copper versions of Thunderbolt 3 cables were released at lengths up to 2 m (6.6 ft). However, shorter lengths up to 0.8 m (3 ft) (initially only available at up to 0.5 m (1.6 ft)) are passive cables offering the full 40 Gbit/s speed. 2 m (6.6 ft) cables are available in two types: passive ones offering only 20Gbit/s speed but cheaper in cost, and more expensive active 2 m (6.6 ft) ones offering the full 40 Gbit/s speed. Additionally, only the passive cables are able to offer compatibility with up to USB 3 (20 Gbit/s) ports, while active ones only support up to USB 2.0 (480 Mbit/s). Much later on, from April 2020, optical Thunderbolt 3 cables were finally released.

---

Honeycomb ceramic is a new type of ceramic product with a honeycomb-like structure. It is widely used in chemical, electric power, metallurgy, petroleum, electronic appliances, machinery and other industries from the earliest use in small automobile exhaust purification, and it is becoming more and more extensive, and its development prospects are considerable. Honeycomb ceramics are composed of numerous and equal pores in various shapes. The maximum number of pores has reached 120 to 140 per square centimeter, the density is 0.3 to 0.6 grams per cubic centimeter, and the water absorption rate is as high as 20%. Due to the characteristics of porous thin wall, the geometric surface area of the carrier is greatly increased and the thermal shock resistance performance is improved. The meshed pores of the produced products are mainly triangular and square. These are especially important as catalytic supports. With the increase of the number of pores per unit area and the decrease of the thickness of the carrier hole wall, the thermal shock resistance of the ceramic carrier increases, and the temperature of thermal shock damage also increases. Therefore, the honeycomb ceramic must reduce the expansion coefficient and increase the pore size per unit area. number. The thermal expansion coefficient is the main performance index. The current foreign level is α25-800℃≤1.0×10-6℃-1, which has a certain gap with the domestic comparison, but the gap is getting smaller and smaller. The earliest raw materials for the production of honeycomb ceramics are mainly kaolin, talc, aluminum powder, clay, etc., especially the application of diatomite, zeolite, expansive soil and refractory materials.
Honeycomb ceramics are more advantageous in catalysts. The honeycomb ceramic material is used as the carrier, and the unique coating material is used to prepare the precious metal, rare earth metal and transition metal, so it has the advantages of high catalytic activity, good thermal stability, long service life, high strength and so on. Honeycomb ceramics for catalytic cracking are replacing existing products. Catalytic cracking uses heavy distillate oil between 200 ~ 500 ℃ as raw material (including vacuum distillate, straight-run light diesel oil, coking wax oil, etc.), uses aluminosilicate as catalyst, and the reaction temperature is between 450 ~ 550 ℃ ( varies by reactor type). It has a large output (each large-scale catalytic cracking unit cracks more than one million tons of oil products per year), and requires high technical conditions (for example, the catalyst needs to be regenerated every few minutes or even seconds when it contacts the oil, and the fluidized bed catalyst flows through the fluidized bed catalyst every minute. Up to 10t or more) With the improvement of catalytic activity, in order to speed up the regeneration, more severe regeneration conditions are required. For example, at 600 to 650 °C, or even 700 °C, the consumption of catalyst is large, and each ton of feed oil consumes 0.3 to 0.6 kg of catalyst. If the mechanical strength of the catalyst is poor, the consumption is much larger. This requires a slight improvement in catalyst activity, selectivity, and stability, which will be of great significance to actual production. Because of this, honeycomb ceramic catalysts are constantly innovating, and the market demand is also increasing. These catalysts for catalytic cracking are replaced by honeycomb ceramic catalysts. Honeycomb ceramic catalysts with large size and number of pores have emerged and have a strong development momentum.
A catalytic converter is part of a car's exhaust system. Catalytic conversion device is an exhaust purification device that converts CO, HC, and NOx in exhaust gas into gases that are harmless to human body by using the action of catalyst, also known as catalytic conversion device. The catalytic conversion device converts the three harmful gases CO, HC, and NOx in the exhaust gas into harmless gases carbon dioxide, nitrogen, Hydrogen and water. According to the purification form of catalytic converter, it can be divided into oxidation catalytic converter, reduction catalytic converter and three-way catalytic converter. The ceramic carrier is also a key component of the catalytic converter. One of its important materials is cordierite, which is resistant to high temperature, with a maximum continuous working temperature of 1200 °C, high strength and low coefficient of linear expansion. The carrier adopts an effective surface and a suitable pore structure. The opening rate of the domestic ceramic carrier can reach 400-460 mesh/inch2, and the minimum wall thickness can reach about 0.16mm. It can enhance the mechanical strength of the catalyst, as well as its ability to resist wear, impact, gravity, compression, high temperature, and phase change, improve the conductivity of the catalyst, and reduce the content of active components. Especially when using precious metal catalysts platinum, palladium and rhodium, the active components can be highly dispersed and the dosage can be reduced. In conclusion, the quality of the carrier is extremely important for the catalyst.
The urea pump is an important part of the urea solution injection metering system. Its main function is to extract the urea solution in the urea tank, maintain a certain pressure, and then deliver it to the injection unit to meet the requirements of the injection metering system for flow and pressure. As an important means of controlling diesel engine exhaust emissions, it has been widely used in developed countries such as Europe, and has played a significant role in improving the environmental pollution caused by exhaust emissions. After using SCR technology, the emission performance of the engine depends to a large extent on the calibration of the urea injection system and the related performance of the urea pump. Based on the basic principle of nitrogen and oxygen reduction, the SCR device uses a 32.5% urea aqueous solution as a reducing agent to reduce NOX in the exhaust gas to N2 and H2O under the catalytic action of the catalyst surface coating. The exhaust temperature of the diesel engine is generally 200-500 °C, which basically meets the activity requirements of the vanadium-based catalyst used in SCR. Therefore, the NOX in the exhaust gas discharged from the diesel engine quickly reacts with the urea aqueous solution to generate nitrogen and water. The urea dosing pump is the core component of the SCR system, and its performance is closely related to the emission function of the engine. In order to ensure that the working reliability of the urea dosing pump meets the working requirements of the SCR system, the urea dosing pump needs to be calibrated.
A nitrogen oxygen sensor or NOx sensor is typically a high-temperature device built to detect nitrogen oxides in combustion environments such as an automobile, truck tailpipe or smokestack. The drive to develop a NOx sensor arises from environmental factors. NOx gases can cause various problems such as smog and acid rain. Many governments around the world have passed laws to limit their emissions (along with other combustion gases such as SOx (oxides of sulfur), CO (carbon monoxide) and CO2 (carbon dioxide) and hydrocarbons). Companies have realized that one way of minimizing NOx emissions is to first detect them and then to employ some sort of feedback loop in the combustion process, thereby enabling the minimization of NOx production by, for example, combustion optimization or regeneration of NOx traps. Therefore, in many applications with exhaust-gas treatment systems, one NOx sensor is used upstream of the exhaust-gas treatment system (upstream) and a second sensor is used downstream of the exhaust-gas treatment system. The upstream sensor is used for the aforementioned feedback loop. Meanwhile, the downstream sensor is used mainly to confirm that the legislated emissions limits have not been exceeded.