2008年12月1日星期一

Computer

A computer is a machine that manipulates data according to a list of instructions.
The first devices that resemble modern computers date to the mid-20th century (1940–1945), although the computer concept and various machines similar to computers existed earlier. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers (PC).Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space.Today, simple computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the Information Age and are what most people think of as "a computer"; however, the most common form of computer in use today is the embedded computer. Embedded computers are small, simple devices that are used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and children's toys.
The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.

It is difficult to identify any one device as the earliest computer, partly because the term "computer" has been subject to varying interpretations over time. Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.
The history of the modern computer begins with two separate technologies - that of automated calculation and that of programmability.
Examples of early mechanical calculating devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when. This is the essence of programmability.
The "castle clock", an astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer.It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour, and five robotic musicians who play music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed every day in order to account for the changing lengths of day and night throughout the year.
The end of the Middle Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers. However, none of those devices fit the modern definition of a computer because they could not be programmed.
In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine".Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.

Earthship

An Earthship is a type of passive solar home made of natural and recycled materials. Designed and marketed by Earthship Biotecture of Taos, NM, the homes are primarily constructed to work autonomously and are generally made of earth-filled tires, utilising thermal mass construction to naturally regulate indoor temperature. They also usually have their own special natural ventilation system. Earthships are a type of off-grid home, which minimizes their reliance on public utilities and fossil fuels.
Earthships are built to utilize the available local resources, especially energy from the sun. For example, windows on the sunny side admit light and heat, and the buildings are often horseshoe-shaped to maximize southern (or northern in the southern hemisphere) sunlight and warmth in the colder months. Likewise, the thick, dense outer walls provide effective insulation against summer heat.
Internal, non-load-bearing walls are often made of a "honey comb" of recycled cans joined by concrete and are referred to as tin can walls. These walls are usually thickly plastered with adobe or stucco.
The Earthship, as it exists today, began to take shape in the 1970s. Mike Reynolds, founder of Earthship Biotecture, a company that specializes in designing and building Earthships, wanted to create a home that would do three things; first, it would be sustainable, using material indigenous to the entire planet as well as recycled materials wherever possible. Second, the homes would rely on natural energy sources and be independent from the “grid”, therefore being less susceptible to natural disasters and free from the electrical and water lines that Reynolds considered unsightly and wasteful. Finally, it would be economically feasible for the average person with no specialized construction skills to be able to create.
Eventually, Reynolds' vision took the form of the common U-shaped earth-filled tire homes seen today. As a concept, the Earthship was not limited to tires - any dense material with a potential for thermal mass, such as concrete, adobe, or stone could theoretically be used to create an Earthship. However, the earth-rammed tire version of the Earthship is now the most common design, and is usually the only structure referred to as “Earthship”.
Unlike other materials, rammed-earth tires are more accessible to the average person. Scrap tires are ubiquitous around the world and easy to come by; there are an estimated 2 billion tires throughout the United States. According to the Scrap Tire Management Council, as many as 253 million scrap tires are generated each year in the United States and of those 253 million tires only 53% are reclaimed by the scrap tire market[citation needed]. In addition to the availability of scrap tires, the method by which they are converted into usable "bricks", the ramming of the earth, is simple and affordable.
The earth rammed tires of an Earthship are usually assembled by teams of two people working together as part of a larger construction team. One member of the two person team shovels dirt, which usually comes from the building site, placing it into the tire one scoop at a time. The second member, who stands on the tire, uses a sledge hammer to pack the dirt in. The second person moves in a circle around the tire to keep the dirt even and avoid warping the tire. All tires in an Earthship are made in place because, when properly made, they weigh as much as 300 pounds and can be very difficult to relocate.
Additional benefits of the rammed earth tire are its great load-bearing capacity and its resistance to fire.
A fully rammed tire, which is about 2 feet 8 inches wide, is massive enough to surpass conventional requirements for structural load distribution to the earth. Because the tire is full of soil, it does not burn when exposed to fire. In 1996 after a fire swept through many conventional homes in New Mexico, an Earthship discovered in the aftermath was relatively unharmed.Only the south-facing wall and the roof had burned away, compared to the total destruction of the conventional homes. After testing the walls of an Earthship in Ridgway, Colorado, engineer Tom Griepentrog said, “It is my opinion that the construction method is equivalent to or better than the general quality, strength, effectiveness, fire resistance, durability and safety that is required by the uniform building code.”Currently, Earthships are in use in almost every state in the United States, as well as many countries in Europe. The use of insulation on the outside of tire walls, which was not common in early designs, is improving the viability of Earthships in every climate without compromising their durability. In the year 2000, Mike Reynolds, in partnership with Daren Howarth, launched Earthship Biotecture Europe, an organization that aims to explore and evolve the concept of the Earthship within a European context. Two more directors were appointed to Earthship Biotecture Europe in July 2006 - Kevan Trott and Kirsten Jacobsen.

Dishwasher


Unlike manual dishwashing, which relies largely on physical scrubbing to remove soiling, the mechanical dishwasher cleans by spraying hot (55–65 degrees Celsius or 130–150 degrees Fahrenheit) water on the dishes. First detergent-added water is used for cleaning purposes, then clean water to remove the detergent residue. Some dishwashers have multiple wash and rinse periods within the complete cycle. In some dishwashers, a rinsing aid can be added to the rinse cycle. As there is no human contact during the process, strong detergents may be used which would be too alkaline for habitual exposure to the skin. Many dishwashers have a heating element to achieve fast drying and sanitation of the dishes. In some models, this element can also be used to heat cold water to the desired wash temperature.

Human dishwashers
The word dishwasher may also refer to a person who washes dishes in a commercial setting. These employees rinse dishes, load them into a stainless steel dishwasher, unload them, and stack them into their respective dish holders. Pots and pans are also washed by hand by scrubbing them in a soap and water mix, immersing them in a rinse of plain water, and then immersing them in a water/sanitizer solution for a period. Silverware is washed by placing loose silverware in a tray, washing them several times like this, then sorting them into circular holders, and washing them again in the dishwasher.

History
The first reports of a mechanical dishwashing device are of an 1850 patent by Joel Houghton of a hand-powered device.
Modern dishwashers are descended from the 1886 invention of Josephine Cochrane, also hand-powered, which she unveiled at the 1893 Chicago World's Fair. Cochrane was quite wealthy and was the granddaughter of John Fitch, the inventor of the steamboat. She never washed dishes herself and only invented the dishwasher as her servants were chipping her fine china.
Models installed with permanent plumbing arrived in the 1920s. In 1937, William Howard Livens invented a small dishwasher suitable for home. It had all the features of a modern dishwasher, including a front door for loading, a wire rack to hold crockery and a rotating sprayer. Electric drying elements were added in 1940.
Adoption was greatest at first in commercial environments, but by the 1970s dishwashers had become commonplace in domestic residences in the US.

Capacity
The international standard for the capacity of a dishwasher is expressed as standard place settings. Dishes or plates of irregular sizes may not fit properly in a dishwasher's cleaning compartment, so it is advisable to check for compatibility before buying a dishwasher.
Commercial dishwashers are rated as plates per hour. The rating is based on standard sized plates of the same size. The same can be said for commercial glass washers, they are based on standard glasses, normally pint glasses.

Size
Dishwashers that are installed into standard kitchen cabinets have a standard width and depth of 60 cm (Europe) or 24 inches (US), and most dishwashers must be installed into a hole a minimum of 86 cm (Europe) or 34 inches (US) tall. Portable dishwashers exist in 45 and 60 cm (Europe) 18 and 24 inch (US) widths, with casters and attached countertops. Dishwashers may come in standard or tall tub designs; standard tub dishwashers have a service kickplate beneath the dishwasher door that allows for simpler maintenance and installation, but tall tub dishwashers have approximately 20% more capacity and better sound dampening from having a continuous front door.

Geomagnetically induced current

Geomagnetically induced currents (GIC), affecting the normal operation of long technological conductor systems, are a manifestation at ground level of space weather. During space weather events (or geomagnetic storms) Earth's near space current systems experience large spatiotemporal variations reflected also in the variations of the Earth’s geomagnetic field. These variations induce currents (GIC) in conductors operated at the surface of Earth. Electric transmission grids and buried pipelines are common examples of such conductor systems. GIC can cause problems such as increased corrosion of pipeline steel and damaged high-voltage power transformers. GIC are one possible consequence of geomagnetic storms, which may also affect geophysical exploration surveys and oil and gas drilling operations.
The Risk to Ground Infrastructures from Geomagnetically Induced Currents

The basic principle for the generation of GIC: variations of the ionospheric currents (I(t)) generate an electric field (E(t)) driving GIC. Shown are also real GIC recordings from the Finnish natural gas pipeline.
A time-varying magnetic field external to the Earth induces electric currents in the conducting ground. These currents create a secondary (internal) magnetic field. As a consequence of Faraday's law of induction, an electric field at the surface of the Earth is induced associated with time variations of the magnetic field. The surface electric field causes electrical currents, known as geomagnetically induced currents (GIC), to flow in any conducting structure, for example, a power or pipeline grid grounded in the Earth. This electric field, measured in V/km, acts as a voltage source across networks.
Examples of conducting networks are electrical power transmission grids, oil and gas pipelines, undersea communication cables, telephone and telegraph networks and railways. GIC are often described as being quasi direct current (DC), although the variation frequency of GIC is governed by the time variation of the electric field. For GIC to be a hazard to technology, the current has to be of a magnitude and occurrence frequency that makes the equipment susceptible to either immediate or cumulative damage. The size of the GIC in any network is governed by the electrical properties and the topology of the network. The largest magnetospheric-ionospheric current variations, resulting in the largest external magnetic field variations, occur during geomagnetic storms and it is then that the largest GIC occur. Significant variation periods are typically from seconds to about an hour, so the induction process involves the upper mantle and lithosphere. Since the largest magnetic field variations are observed at higher magnetic latitudes, GIC have been regularly measured in Canadian, Finnish and Scandinavian power grids and pipelines since the 1970s. GIC of tens to hundreds of Amperes have been recorded. GIC have also been recorded at mid-latitudes during major storms. There may even be a risk to low latitude areas, especially during a storm commencing suddenly because of the high, short-period rate of change of the field that occurs on the dayside of the Earth.
GIC have been known since the mid-1800s when it was noted that electrical telegraph systems could sometimes run without power during geomagnetic storms, described at the time as operating on the “celestial battery”, while at other times they were completely inoperative . See also: Aurora (astronomy)

GIC in power grids
Modern electric power transmission systems consist of generating plants inter-connected by electrical circuits that operate at fixed transmission voltages controlled at substations. The grid voltages employed are largely dependent on the path length between these substations and 200kV-700kV system voltages are common. There is a trend towards higher voltages and lower line resistances to reduce transmission losses over longer and longer path lengths. Low line resistances produce a situation favourable to the flow of GIC. Power transformers have a magnetic circuit that is disrupted by the quasi-DC GIC: the field produced by the GIC offsets the operating point of the magnetic circuit and the transformer may go into half-cycle saturation. This produces a harmonic-rich AC waveform, localised heating and leads to high reactive power demands, inefficient power transmission and possible mis-operation of protective measures. Balancing the network in such situations requires significant additional reactive power capacity . The magnitude of GIC that will cause significant problems to transformers varies with transformer type. Modern industry practice is to specify GIC tolerance levels on new transformers.
On 13 March 1989 a severe geomagnetic storm caused the collapse of the Hydro-Québec power grid in a matter of seconds as equipment protection relays tripped in a cascading sequence of events . Six million people were left without power for nine hours, with significant economic loss. Since 1989 power companies in North America, the UK, Northern Europe and elsewhere have invested in evaluating the GIC risk and in developing mitigation strategies.
GIC risk can, to some extent, be reduced by capacitor blocking systems, maintenance schedule changes, additional on-demand generating capacity, and ultimately, load shedding. These options are expensive and sometimes impractical. The continued growth of high voltage power networks results in higher risk. This is partly due to the increase in the interconnectedness at higher voltages; connections in terms of power transmission to grids in the auroral zone, and grids operating closer to capacity than in the past.
To understand the flow of GIC in power grids and to advise on GIC risk, analysis of the quasi-DC properties of the grid is necessary . This must be coupled with a geophysical model of the Earth that provides the driving surface electric field, determined by combining time-varying ionospheric source fields and a conductivity model of the Earth. Such analyses have been performed for North America, the UK and in Northern Europe. The complexity of power grids, the source ionospheric current systems and the 3D ground conductivity make an accurate analysis difficult . By being able to analyse major storms and their consequences we can build a picture of the weak spots in a transmission system and run hypothetical event scenarios.
Grid management is also aided by space weather forecasts of major geomagnetic storms. This allows for mitigation strategies to be implemented. Solar observations provide a 1-3 day warning of an Earth-bound coronal mass ejection (CME), depending on CME speed. Following this, detection of the solar wind shock that precedes the CME in the solar wind, by spacecraft at the Lagrangian L1 point, gives a definite 20-60 minutes warning of a geomagnetic storm (again depending on local solar wind speed). The magnitude and arrival time of a CME after detection is unknown, although there is much research and model development within the space weather community.

Electric blanket


An electric blanket is a blanket with an integrated electrical heating device usually placed above the top bed sheet. Another variation of the electric blanket is the electric mattress pad, which is placed below the bottom bed sheet. Electric blankets usually have a control unit which adjusts the amount of heat the blanket produces. Blankets for larger sized beds often have separate controls for each side of the bed. The electric blanket may be used to pre-heat the bed before use or to keep the occupant warm while in bed.
Modern electric blankets have carbon fibre wires that are barely noticeable and produce heat in the far infra-red part of the spectrum, penetrating through other clothes. These blankets usually work on 24 volts instead of the 110/240 volts. Therefore, they are advertised as being a safer, more efficient and more comfortable alternative.

Safety concerns
Due to the combination of heat, electricity, the abundance of flammable bedding material, and a sleeping occupant, the use of electric blankets is of concern to fire safety officials internationally. Of primary concern are blankets that are older than 10 years and/or have been subject to damage, by creasing, flexing, fraying, or ordinary wear and tear. In the UK, it is estimated that 5,000 fires per year are caused by faulty electric blankets, of which 99% are believed to have been caused by blankets 10 years or older.
Electric blankets also present a burn risk to those who cannot feel pain or are unable to react to it. Individuals included in this group are small children, diabetics, and the elderly.

Popular culture
An anthropomorphic-faced cartoon electrical blanket named "Blanky" was portrayed in the 1987 film The Brave Little Toaster .


mini coffee grinder


keyring led light


12V Battery Charger


dual fuel generator


car backup sensor


air cooled condenser


gas engine scooter


automotive rocker switch


Optical Wired Mouse


digital fishing scales


Conveyor Roller Bearing


Mirror Ball Motor


Portable Cassette Radio


Wireless Speaker Amplifier


Car Amplifier Installation


Laser Diode Pump


TFT-LCD Color TV


Power Window Regulator


Steam Bath Generator


adhesive vinyl sheets


hydraulic pressure regulator


Machine Tig Welding


hydraulic piston cylinder


Power Splitter Cable


electric valve actuator


glass solar collector


ozone generator water


Mechanical Pump Seal


electric mini scooters


Laser Wire Stripping

2008年11月10日星期一

Tall bike

A tall bike is an unusually tall bicycle, typically built for the purpose of fun and recreation, though with occasional practical use.

Modern tall bikes are most commonly constructed by individuals from spare parts. Two conventional bicycle frames are connected, by welding, brazing, or other means, one atop the other. The drive train is reconfigured to connect to the upper set of pedals, and the controls are moved to the upper handlebar area.

Alternatively, a bicycle can be built by inverting the frame, and inserting the forks from the 'wrong side', flipping the rear wheel, and adding a long gooseneck and tall handlebars, then welding a long seatpost tube to the 'bottom' (now the top) of the frame. This type of tall bike is made with only one bike frame, and is often called an upside-down bike rather than a tall bike, though the seat can be quite high, depending on the frame shape used. This type can be somewhat safer, as there is less tubing between the rider's legs and dismounting in a hurry can be easily accomplished.

Tall bikes are a popular mode of transportation for modern 'bicycle clubs' (SCUL, Rat Patrol, Zoobomb, Black Label Bike Club, The Winking Circle, Dead Baby Bikes, C.h.u.n.k. 666, Cyclecide, etc.) and activist groups. They are also a mainstay among builders of Clown bikes, art bikes, Clown alleys and parade groups. Bicycle modification is considered a fun and cheap hobby, and never fails to attract a lot of attention. Most modern cities contain large quantities of unused or abandoned bicycles that provide the raw materials for tall bikes and other mutant cycles.
Practical uses

Tall bikes can be used for general transportation and recreation, just like other bicycles. Regular tall-bike commuters note that both their increased visibility and the simple 'wow factor' give them a safety advantage in automobile traffic over 'short bikes.'

A Giraffe Lamplighter Bicycle, manufactured in 1898.

Historically, one of the first practical uses of the tall bike was as a late 1800s lamp lighting system, by which a worker would mount a specialized tall bicycle while equipped with a torch for lighting gas lamps. As the worker rode to each lamp, they would lean against the lamp post, light the lamp, and then ride to the next. Upon completing the circuit of lamps, an assistant would help the rider dismount.

In Bugbrooke, Northamptonshire, England The Clark Brothers in the 1950s built tall bikes to get to work when it flooded. These bikes they called 'Flood Bikes'. They have been on BBC TV and even did a Welsh language programme on them. They are currently in a museum somewhere.

Sporting

Tall bike jousting is a popular sport among bicycle hackers, and is commonly considered to have been introduced by Jake Houle and Lil' Bob of the Hard Times/Black Label Bike Club. Combatants arm themselves with lances, and attempt to score points by dislodging the other rider. Rules vary by area, and with the mood of the combatants. Like all jousting games, participants consider it a sport where honor plays a role and dishonorable wins are frowned upon.

Jousters create lances that vary from simple PVC pipe and foam devices that are flexible, soft, and relatively safe, up to wooden or metal lances that may be quite dangerous. Regional rules vary, some specifying flaming lances for effect, or glass containers attached to the end, the goal being to break the glass container in order to score points.

Design considerations

Tall bikes present some interesting design considerations, and different localities tend to have different methods of dealing with them.

One consistent issue is that the seat tends to end up in line with, or behind, the rear axle, which creates a powerful tendency to lift the front wheel of the bicycle on acceleration. Some bicycle builders simply accept this tendency, but others solve the problem by moving the seat post forward, lowering the handlebars, or by using a smaller wheel in front, typically a 24" instead of a 26".

Stability can also be negatively affected, and enhancements such as extended wheelbase by welding extensions on the front and rear dropouts can benefit stability. Contest holders often place restrictions on such modification to prevent unfair advantages.

See the bicycle and motorcycle geometry and bicycle and motorcycle dynamics articles for more on these issues.


Bamboo Table Set


mirror wall tile


Ride On Motorbike


Socket Tool Set


embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Electric motor

An electric motor uses electrical energy to produce mechanical energy. The reverse process, that of using mechanical energy to produce electrical energy, is accomplished by a generator or dynamo. Traction motors used on locomotives and some electric and hybrid automobiles often perform both tasks if the vehicle is equipped with dynamic brakes. Electric motors are found in household appliances such as fans, refrigerators, washing machines, pool pumps, floor vacuums, and fan-forced ovens. They are also found in many other devices such as computer equipment, in its disk drives, printers, and fans; and in some sound and video playing and recording equipment as DVD/CD players and recorders, tape players and recorders, and record players. Electric motors are also found in several kinds of toys such as some kinds of vehicles and robotic toys.

The principle of conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821 and consisted of a free-hanging wire dipping into a pool of mercury. A permanent magnet was placed in the middle of the pool of mercury. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a circular magnetic field around the wire. This motor is often demonstrated in school physics classes, but brine (salt water) is sometimes used in place of the toxic mercury. This is the simplest form of a class of electric motors called homopolar motors. A later refinement is the Barlow's Wheel. These were demonstration devices, unsuited to practical applications due to limited power.

The first real electric motor, using electromagnets for both stationary and rotating parts, was demonstrated by Ányos Jedlik in 1828 Hungary. He built an electric-motor propelled vehicle in 1828.

The first English commutator-type direct-current electric motor capable of a practical application was invented by the British scientist William Sturgeon in 1832. Following Sturgeon's work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American Thomas Davenport and patented in 1837. Although several of these motors were built and used to operate equipment such as a printing press, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same cost issues with primary battery power. No electricity distribution had been developed at the time. Like Sturgeon's motor, there was no practical commercial market for these motors.

The modern DC motor was invented by accident in 1873, when Zénobe Gramme connected the dynamo he had invented to a second similar unit, driving it as a motor. The Gramme machine was the first electric motor that was successful in the industry.

In 1888 Nikola Tesla invented the first practicable AC motor and with it the polyphase power transmission system. Tesla continued his work on the AC motor in the years to follow at the Westinghouse company.


Bamboo Table Set


mirror wall tile


Ride On Motorbike


Socket Tool Set


embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Small appliance

Small appliance refers to a class of home appliances that are portable or semi-portable or which are used on tabletops, countertops, or other platforms. Such items are contrasted with major appliances, which are typically fixtures that cannot be easily moved. All appliances are intended to perform, enable, or assist in performing a job or changing a status, such as the humidity of a room. In this way, they can be differentiated from other portable electrical items that provide only entertainment. Some items not typically considered appliances, such as lamps, can be used as appliances if they are used to cook or warm food.

Many small appliances are powered by electricity. The appliance may use a permanently attached cord which is plugged into a wall outlet or a detachable cord. The appliance may have a cord storage feature. A few hand-held appliances use batteries, which may be disposable or rechargeable. Some appliances consist of an electrical motor upon which is mounted various attachments so as to constitute several individual appliances, such as a blender, a food processor, or a juicer. Many stand mixers, while functioning primarily as a mixer, have attachments which can perform additional functions.

A few gas-powered appliances exist for use in situations where electricity is not expected to be available, but these are typically larger and not as portable as most small appliances. Items that perform the same function as small appliances but are hand powered are generally referred to as tools or gadgets, for example a hand-powered meat grinder.

Some small appliances perform the same or similar function as their larger counterparts. For example, a toaster oven is a small appliance that performs a similar function as an oven. Small appliances often have a home version and a commercial version. The commercial, or industrial, version is designed to be used nearly continuously in a restaurant or other similar setting. Commercial appliances are typically connected to a more powerful electrical outlet, are larger and stronger, have more user-serviceable parts, and cost significantly more.

Small appliances can be very inexpensive, such as a basic can opener or coffee maker which may cost only a few U.S. dollars, or very expensive, such as an elaborate espresso maker, which may cost several thousand U.S. dollars. Most homes contain several cheaper home appliances, with perhaps a few more expensive appliances, such as a high-end microwave oven or mixer.

Small appliances which are defective or improperly used or maintained may cause house fires and other property damage, or may harbor bacteria if not properly cleaned. It is important that users read the instructions carefully and that appliances that use a grounded cord be attached to a grounded outlet. Because of the risk of fire, some appliances have a short detachable cord that is connected to the appliance magnetically. If the appliance is moved further than the cord length from the wall, the cord will detach from the appliance.


Bamboo Table Set


mirror wall tile


Ride On Motorbike


Socket Tool Set


embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Locomotive

A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco - "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine,. first used in the early 19th century to distinguish between mobile and stationary steam engines.

A locomotive has no payload capacity of its own, and its sole purpose is to move the train along the tracks. In contrast, some trains have self-propelled payload-carrying vehicles. These are not normally considered locomotives, and may be referred to as multiple units, motor coaches or railcars. The use of these self-propelled vehicles is increasingly common for passenger trains, but very rare for freight (see CargoSprinter). Vehicles which provide motive power to haul an unpowered train, but are not generally considered locomotives because they have payload space or are rarely detached from their trains, are known as power cars.

Traditionally, locomotives pull trains from the front. Increasingly common is push-pull operation, where a locomotive pulls the train in one direction and pushes it in the other, and is optionally controlled from a control cab at the opposite end of the train.

The first successful locomotives were built by Cornish inventor Richard Trevithick. In 1804 his unnamed steam locomotive hauled a train along the tramway of the Penydarren ironworks, near Merthyr Tydfil in Wales. Although the locomotive hauled a train of 10 tons of iron and 70 passengers in five wagons over nine miles (14 km), it was too heavy for the cast iron rails used at the time. The locomotive only ran three trips before it was abandoned. Trevithick built a series of locomotives after the Penydarren experiment, including one which ran at a colliery in Tyneside where it was seen by the young George Stephenson.

The first commercially successful steam locomotive was Matthew Murray's rack locomotive, The Salamanca, built for the narrow gauge Middleton Railway in 1812. This was followed in 1813 by the Puffing Billy built by Christopher Blackett and William Hedley for the Wylam Colliery Railway, the first successful locomotive running by adhesion only. Puffing Billy is now on display in the Science Museum in London, the oldest locomotive in existence.

In 1814 George Stephenson, inspired by the early locomotives of Trevithick and Hedley persuaded the manager of the Killingworth colliery where he worked to allow him to build a steam-powered machine. He built the Blücher, one of the first successful flanged-wheel adhesion locomotives. Stephenson played a pivotal role in the development and widespread adoption of steam locomotives. His designs improved on the work of the pioneers. In 1825 he built the Locomotion for the Stockton and Darlington Railway which became the first public steam railway. In 1829 he built The Rocket which was entered in and won the Rainhill Trials. This success led to Stephenson establishing his company as the pre-eminent builder of steam locomotives used on railways in the United Kingdom, the United States and much of Europe.


Bamboo Table Set


mirror wall tile


Ride On Motorbike


Socket Tool Set


embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


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Iron

An iron is a small appliance used in ironing to remove wrinkles from fabric. Ironing works by loosening the ties between the long chains of molecules that exist in polymer fiber materials. With the heat and the weight of the ironing plate, the fibers are stretched and maintain its new shape when cooled. Some materials such as cotton require the use of water to loosen the intermolecular bonds. Many materials developed in the twentieth century are advertised as not needing or needing only a little ironing

Metal pans filled with charcoal were used for smoothing fabrics in China in the 1st century BC[citation needed]. From the 17th century, sadirons or sad irons (from an old word meaning solid) began to be used. They were thick slabs of cast iron, delta-shaped and with a handle, heated in a fire. These were also called flat irons. A later design consisted of an iron box which could be filled with hot coals, which had to be periodically aerated by attaching a bellows. In Kerala in India, burning coconut shells were used instead of charcoal, as they have a similar heating capacity. This method is still in use as a backup device since power outage is frequent. Other box irons had heated metal inserts instead of hot coals. Another solution was a cluster of solid irons that were heated from the single source: as the iron currently in use cools down, it can be quickly replaced by another one that is hot.

In the late nineteenth and early twentieth centuries, there were many irons in use which were heated by a fuel such as kerosene, alcohol, whale oil, natural gas, carbide gas (acetylene) as with carbide lamps, or even gasoline. Some houses were equipped with a system of pipes for distributing natural gas or carbide gas to different rooms in order to operate appliances such as irons, in addition to lights. Despite the risk of fire, liquid-fuel irons were sold in U.S. rural areas up through World War II.

In the industrialized world, these designs have been superseded by the electric iron, which uses resistive heating from an electric current. The hot plate, called the sole plate, is made of aluminium or stainless steel. The heating element is controlled by a thermostat which switches the current on and off to maintain the selected temperature. The invention of the resistively heated electric iron is credited to Henry W. Seely of New York in 1882. In the same year an iron heated by a carbon arc was introduced in France, but was too dangerous to be successful. The early electric irons had no easy way to control their temperature, and the first thermostatically controlled electric iron appeared in the 1920s. Later, steam was used to iron clothing. Credit for the invention of the steam iron goes to Thomas Sears.


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embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Pylon transformer

Pylon transformers are normally located at a service drop, where wires run from a utility pole to a customer's premises. They are often used for the power supply of facilities outside settlements, such as isolated houses, farmyards or pumping stations at voltages below 30kV. Another application is the power supply of switch heatings from the overhead wire of railways electrified with AC. In this case single phase pylon transformers are used.
In North American utility practice, these devices are very commonly used in areas with overhead primary distribution lines. An alternative to a pole pig is used with underground distribution systems; a transformer in a locked steel case mounted on a concrete pad on the customer's premises. This is called a pad mount transformer. They are used in many urban areas and neighborhoods where the primary distribution lines run underground. Many large buildings have electric service provided at primary distribution voltage. These buildings have customer-owned transformers in the basement for step-down purposes.
High voltage hobbyists often use these transformers in reverse (step-up) by feeding 120 or 240 volts into the secondary and drawing the resulting high voltage off the primary bushings, using it to power devices like Jacob's Ladders and Tesla coils.

Connections
Both pole mount and pad mount transformers convert the high voltage of the 'primary' overhead or underground distribution lines to the lower voltage of the 'secondary' distribution wires inside the building. The primary wires supply power using the three phase system, so there are three wires, at one of a wide range of standard voltages from 4,600 to 33,000 volts but most commonly 7,200 or 14,400 volts.

Primary
The high voltage primary windings are brought out to bushings on the top of the case. Single phase transformers, generally used in the USA system, are attached to the overhead wires with two different types of connections:
If a primary neutral wire is available, a 'wye' or 'phase to neutral' transformer can be used. This usually has only one bushing on top, connected to one of the primary phases. The other end of the primary winding is 'grounded' to the transformer's case, which is connected to the neutral wire of the 3 phase system, and also earth ground. This type of distribution system, called 'grounded wye', is preferred because the pylon transformers present unbalanced loads on the line, causing currents in the neutral wire. With the 'delta' connection, this can cause variations in the voltages on the 3 phase wires.
If no neutral wire is available, a 'delta' or 'phase to phase' transformer must be used. This has two bushings on top which are connected to two of the three primary wires, so the voltage across the primary winding is the phase-to-phase voltage. This type is used on long distribution lines where it is uneconomical to run a fourth neutral wire.
Transformers providing three-phase secondary power, which are used for residential service in the European system, have three secondary windings and are attached to all three primary phase wires. The transformer is always connected to the primary distribution lines through protective fuses and disconnect switches. In the USA this usually takes the form of a 'fused cutout'. An electrical fault causes the fuse to melt, and the device drops open to give a visual indication of trouble. It can also be manually opened while the line is energized by lineworkers using insulated hot sticks.

Secondary
The low voltage secondary windings are attached to three terminals on the transformer's side.
In the USA and countries using its system, the secondary is most often the single phase 240/120 volt system. The 240 V secondary winding is center-tapped and the center neutral wire is grounded, making the two end conductors "hot" with respect to the center tap. These three wires run down the service drop to the electric meter and service panel inside the building. Connecting a load between either hot wire and the neutral gives 120 volts. Connecting between both hot wires gives 240 volts.
In Europe and countries using its system, the secondary is often the three phase 416Y/240 system. There are three 240 V secondary windings, each receiving power from a primary winding attached to one of the primary phases. The three secondary windings are connected together to a 'neutral' wire, which is grounded. The other end of the 3 secondary windings, along with the neutral, are brought down the service drop to the service panel. 240 V loads are connected between any of the three phase wires and the neutral.
Higher secondary voltages, such as 480 volts, are sometimes required for commercial and industrial uses. Some industrial customers require three-phase power at secondary voltages. To provide this, three-phase transformers can be used, or three identical single phase transformers can be wired in a transformer bank in either a wye or delta connection.

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mirror wall tile


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embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Electromagnetic interference

Integrated circuits are often a source of EMI, but they are never the "antenna". They must couple their energy to larger objects such as heatsinks, circuit board planes and cables to radiate significantly .
On integrated circuits, important means of reducing EMI are: the use of bypass or "decoupling" capacitors on each active device (connected across the power supply, as close to the device as possible), rise time control of high-speed signals using series resistors, and VCC filtering. Shielding is usually a last resort after other techniques have failed because of the added expense of RF gaskets and the like.
The efficiency of the radiation depends on the height above the ground or power plane (at RF one is as good as the other) and the length of the conductor in relation to the wavelength of the signal component (fundamental, harmonic or transient (overshoot, undershoot or ringing)). At lower frequencies, such as 133 MHz, radiation is almost exclusively via I/O cables; RF noise gets onto the power planes and is coupled to the line drivers via the VCC and ground pins. The RF is then coupled to the cable through the line driver as common-mode noise. Since the noise is common-mode, shielding has very little effect, even with differential pairs. The RF energy is capacitively coupled from the signal pair to the shield and the shield itself does the radiating. One cure for this is to use a braid-breaker or choke to reduce the common-mode signal.
At higher frequencies, usually above 500 MHz, traces get electrically longer and higher above the plane. Two techniques are used at these frequencies: wave shaping with series resistors and embedding the traces between the two planes. If all these measures still leave too much EMI, shielding such as RF gaskets and copper tape can be used. Most digital equipment is designed with metal, or conductive-coated plastic, cases.

Susceptibilities of different radio technologies
Interference tends to be more troublesome with older radio technologies such as analogue amplitude modulation, which have no way of distinguishing unwanted in-band signals from the intended signal, and the omnidirectional dipole antennas used with broadcast systems. Newer radio systems incorporate several improvements that improve the selectivity. In digital radio systems, such as Wi-Fi, error-correction techniques can be used. Spread-spectrum and frequency-hopping techniques can be used with both analogue and digital signalling to improve resistance to interference. A highly directional receiver, such as a parabolic antenna or a diversity receiver, can be used to select one signal in space to the exclusion of others.
The most extreme example of digital spread-spectrum signalling to date is ultra-wideband (UWB), which proposes the use of large sections of the radio spectrum at low amplitudes to transmit high-bandwidth digital data. UWB, if used exclusively, would enable very efficient use of the spectrum, but users of non-UWB technology are not yet prepared to share the spectrum with the new system because of the interference it would cause to their receivers. The regulatory implications of UWB are discussed in the Ultra-wideband article.

Interference to consumer devices
Complex electronic circuitry is found in all sorts of devices used in the home. This results in a vast interference potential that didn't exist in earlier, simpler decades. In the US, Public Law 97-259, enacted in 1982, gave the FCC the authority to regulate the susceptibility of consumer electronic equipment sold in the United States. The FCC, working with equipment manufacturers, decided to allow them to develop standards for EMI immunity and implement their own voluntary compliance programs.
Broadcast transmitters, two-way radio transmitters, paging transmitters, and cable TV are potential sources of RFI and EMI.Other possible sources of interference include a wide variety of devices, such as doorbell transformers, toaster ovens, electric blankets, ultrasonic pest control devices, electric bug zappers, heating pads, and touch controlled lamps. Multiple CRT computer monitors or televisions sitting too close to one another can sometimes cause a "shimmy" effect in each another, due to the electromagnetic nature of their picture tubes, especially when one of their de-gaussing coils is activated.
Switching inductive loads, such as electric motors, off causes interference, but it is easily suppressed by connecting a snubber network, a resistor in series with a capacitor, across the switch. Exact values can be optimised for each case, but 100 ohms in series with 100 nanofarads is usually satisfactory.
Switched-mode power supply can be a source of EMI, but have become less of a problem as design techniques have improved, such as integrated power factor correction.
Most countries have legal requirements that mandates electromagnetic compatibility: electronic and electrical hardware must still work correctly when subjected to certain amounts of EMI, and should not emit EMI which could interfere with other equipment (such as radios).


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mirror wall tile


Ride On Motorbike


Socket Tool Set


embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Heating pad

Electrical
Electric pads usually operate from household current and must have protection against overheating.
A moist heating pad is used dry on the user's skin. These pads register temperatures from 170 to 180 degrees Fahrenheit (76 to 82 °C) and are intended for deep tissue treatment and can be dangerous if left on unattended. Moist heating pads are used mainly by physical therapists but can be found for home use. A moist cloth can be added with a stupe cover to add more moisture to the treatment.

Chemical
Chemical pads employ a chemical heat reservoir or a one-time chemical reaction such as catalyzed rusting of iron.

A sodium acetate heat pad
A sodium acetate heat pad is a reusable heat reservoir. It contains a supersaturated solution of sodium acetate (CH3COONa). Crystallization is triggered by flexing a (patented ) small flat disc of notched ferrous metal embedded in the liquid. Pressing the disc releases very tiny adhered crystals of sodium acetate into the solution which then act as nucleation sites for the recrystallization of the remainder of the salt solution. Because the liquid is supersaturated, this makes the solution crystallize suddenly, thereby releasing the energy of the crystal lattice.
See sodium acetate for a more technical discussion.
The pad can be reused by placing it in boiling water for 10-15 minutes, which redissolves the sodium acetate in the contained water and recreates a supersaturated solution. Once the pad has returned to room temperature it can be triggered again. Triggering the pad before it has reached room temperature results in the pad reaching a lower peak temperature, as compared to waiting until it had completely cooled.

High specific-heat capacity materials
Heating packs can also be made by filling a container with a material that has a high specific heat capacity, which then gradually releases the heat over time. A hot water bottle is the most familiar example of this type of heating pad.
A microwavable heating pad is a heating pad that is warmed by placing it in a microwave oven before use. Microwavable heating pads are typically made out of a thick insulative fabric such as flannel and filled with grains such as buckwheat or flax seed. Due to their relative simplicity to make, they are frequently sewn by hand, often with a custom shape to fit the intended area of use. In rare instances, these types of pads have been known to ignite during or after the microwave process and cause fires.
Often, aromatic compounds will also be added to the filler mixture to create a pleasant or soothing smell when heated. The source of these can vary significantly, ranging from adding essential oils to ground up spices such as cloves and nutmeg, or even dried rose petals.


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vinyl acetate monomer


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Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Roller printing on textiles

Roller printing, also called cylinder printing or machine printing, on fabrics is a textile printing process patented by Thomas Bell of Scotland in 1783 in an attempt to reduce the cost of the earlier copperplate printing. This method was used in Lancashire fabric mills to produce cotton dress fabrics from the 1790s, most often reproducing small monochrome patterns characterized by striped motifs and tiny dotted patterns called "machine grounds".

Improvements in the technology resulted in more elaborate roller prints in bright, rich colours from the 1820s; Turkey Red and chrome yellow were particularly popular.Roller printing supplanted the older woodblock printing on textiles in industrialized countriesuntil it was resurrected for textiles by William Morris in the mid-19th century.

The printing of textiles from engraved copperplates was first practiced by Bell in 1770. It was entirely obsolete, as an industry, in England, by the end of the 19th century.

The presses first used were of the ordinary letterpress type, the engraved plate being fixed in the place of the type. In later improvements the well-known cylinder press was employed; the plate was inked mechanically and cleaned off by passing under a sharp blade of steel; and the cloth, instead of being laid on the plate, was passed round the pressure cylinder. The plate was raised into frictional contact with the cylinder and in passing under it transferred its ink to the cloth.

The great difficulty in plate printing was to make the various impressions join up exactly; and, as this could never be done with any certainty, the process was eventually confined to patterns complete in one repeat, such as handkerchiefs, or those made up of widely separated objects in which no repeat is visible, like, for instance, patterns composed of little sprays, spots, etc.


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vinyl acetate monomer


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AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight

Laser engraving

Laser engraving is the practice of using lasers to engrave or mark an object. The technique can be very technical and complex, and often a computer system is used to drive the movements of the laser head. Despite this complexity, very precise and clean engravings can be achieved at a high rate. The technique does not involve tool bits which contact the engraving surface and wear out. This is considered an advantage over alternative engraving technologies where bit heads have to be replaced regularly.

The impact of laser engraving has been more pronounced for specially-designed "laserable" materials. These include polymer and novel metal alloys.

In situations where physical alteration of a surface by engraving is undesirable, an alternative such as "marking" is available. This is a generic term that covers a broad spectrum of surfacing techniques including printing, hot-branding and laser bonding. In many instances, laser engraving machines are able to do marking that would have been done by other processes.
A laser engraving machine can be thought of as three main parts: a laser, a controller, and a surface. The laser is like a pencil - the beam emitted from it allows the controller to trace patterns onto the surface. The controller (usually a computer) controls the direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The surface is picked to match what the laser can act on.

There are three main genres of engraving machines: The most common is the X-Y table where, usually, the workpiece (surface) is stationary and the laser moves around in X and Y directions drawing vectors. Sometimes the laser is stationary and the workpiece moves. Sometimes the workpiece moves in the Y axis and the laser in the X axis. A second genre is for cylindrical workpieces (or flat workpieces mounted around a cylinder) where the laser effectively traverses a fine helix and on/off laser pulsing produces the desired image on a raster basis. In the third method, both the laser and workpiece are stationary and galvo mirrors move the laser beam over the workpiece surface. Laser engravers using this technology can work in either raster or vector mode.

The point where the laser (the terms "laser" and "laser beam" may be used interchangeably) touches the surface should be on the focal plane of the laser's optical system, and is usually synonymous with its focal point. This point is typically small, perhaps less than a fraction of a millimeter (depending on the optical wavelength). Only the area inside this focal point is significantly affected when the laser beam passes over the surface. The energy delivered by the laser changes the surface of the material under the focal point. It may heat up the surface and subsequently vaporize the material, or perhaps the material may fracture (known as "glass" or "glass up") and flake off the surface. This is how material is removed from the surface to create an engraving.


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mirror wall tile


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Socket Tool Set


embroidered denim jeans


Plastic Ball Valve


foam folding chair


decorative glass bottle


blister packaging machinery


vinyl acetate monomer


Impact Screw Driver


Bicycle Spare Parts


AA Battery Case


iron stepping stone


cotton tote bags


Portable Car Lifts


european leather sofa


electric soldering iron


VoIP USB Handset


Heavy Duty Webbing


solenoid valve coil


key selector switch


Floating Ball Light


Yarn Dyed Shirt


USB DVB Stick


bathroom wall panel


metal engraving machine


electric heating pad


Black CRT Monitor


acrylic paper weight