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Virtual Fence
An electric fence is a barrier that uses electric shocks to deter humans and other animals from crossing a boundary. Most electric fences are used for agricultural purposes and other non-human animal control. They may also be used to protect high-security areas such as military installations or prisons, where potentially lethal voltages may be applied. Virtual electric fences for livestock using GPS technology have also been developed. Design and function Electric fences are designed to shock animals or humans if they attempt to cross the boundary. A component called a power energiser converts power into a brief high voltage pulse. One terminal of the power energiser releases an electrical pulse along a connected bare wire about once per second. Another terminal is connected to a metal rod implanted in the earth, called a ground or earth rod. An animal touching both the wire and the earth during a pulse will complete an electrical circuit and will conduct the pulse, causing a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stainless Steel
Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromium content of 11% or more, which forms a Passivation (chemistry), passive film that protects the material and can self-healing material, self-heal when exposed to oxygen. It can be further alloyed with elements like molybdenum, carbon, nickel and nitrogen to enhance specific properties for various applications. The alloy's properties, such as luster and resistance to corrosion, are useful in many applications. Stainless steel can be rolled into Sheet metal, sheets, plates, bars, wire, and tubing. These can be used in cookware, cutlery, surgical instruments, major appliances, vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills, chemical plants, water treatment), and storage tanks and tankers for ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invisible Fence Inc
Invisible Fence Inc. (commonly referred to as Invisible Fence Brand) is a company that designs radio pet fences for cats and dogs. Manufactured and distributed by Radio System Corporation, the company sells wireless and fenceless systems that were first introduced in 1973. Its best-known product consists of an underground wire and a collar with an integrated transmitter that provides a signal to the pet when it approaches the perimeter. History In the 1970s, traveling salesman Richard Peck worked as a sales and product manager for companies in Pennsylvania. His work took him from city to city, and as he drove through these towns, he noticed the number of dead pets lying along highways and city streets. He developed the idea of an "Invisible Fence". In 1973, he received a patent for the concept to build the first invisible fence. Peck formed a company called Stay-Put Sales Co. and marketed his product mainly through direct mail and magazines. In 1976, Peck sold the marketing and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pet Fence
A pet fence or radio fence, is an electronic system designed to keep a pet or other domestic animal within a set of predefined boundaries without the use of a physical barrier. A mild electric shock is delivered by an electronic collar if its warning sound is ignored. The system was first invented and patented by Richard Peck in 1973. History The pet fence was created in 1973 by Richard Peck. Peck was a traveling salesman and through his travels, he saw enough dogs hit by cars that it led to him creating the pet fence system. In 1976, salesman John Purtell bought the rights to the pet fence and rebranded it as "Invisible Fence" which offered a different option for pet owners in terms of pet containment. In 1990, Invisible Fence Co became Invisible Fence Inc. Technology A typical invisible fence transmits a radio signal that takes the geometric shape of the area that is enclosed by the system. The pet wears a lightweight collar that emits a sensory cue, such as a warning sound, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
City Of Johannesburg Metropolitan Municipality
The City of Johannesburg Metropolitan Municipality () is a metropolitan municipality that manages the local governance of Johannesburg, the largest city in South Africa. It is divided into several branches and departments in order to expedite services for the city. Zulu is the most spoken home language at 23.4% followed by English at 20.1%. Johannesburg is a divided municipality: the poor mostly live in the southern suburbs or on the peripheries of the far north, and the middle- and upper class live largely in the suburbs of the central and north. As of 2012, unemployment is near 25% and most young people are out of work. Around 20% of the municipality lives in abject poverty in informal settlements that lack proper roads, electricity, or any other kind of direct municipal service. History Following the end of the apartheid era, in April 1991 the Central Witwatersrand Metropolitan Chamber was formed as a "people-based" negotiating forum prior to holding a democratic election a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crime In South Africa
Crime in South Africa includes all violent and non-violent crimes that take place in the country of South Africa, or otherwise within its jurisdiction. When compared to other countries, South Africa has notably high rates of violent crime and has a reputation for consistently having one of the highest murder rates in the world. The country also experiences high rates of Organized crime, organised crime relative to other countries. Causes Crime levels have been attributed to poverty, problems with delivery of public services, and wealth disparity. The Institute for Security Studies also highlighted factors beyond poverty and inequality in post-apartheid South Africa, inequality, particularly social stress from uncaring environments in early childhood and subsequent lack of guardianship. South Africa's high crime rates, recidivism and overburdened criminal justice system have been described as a crisis which will require a radical rethink of Law, crime and punishment in young peo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wildfire
A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire (Bushfires in Australia, in Australia), desert fire, grass fire, hill fire, Peat#Peat fires, peat fire, prairie fire, vegetation fire, or veld fire. Some natural forest ecosystems Fire ecology, depend on wildfire. Modern forest management often engages in prescribed burns to mitigate fire risk and promote natural forest cycles. However, controlled burns can turn into wildfires by mistake. Wildfires can be classified by cause of ignition, physical properties, combustible material present, and the effect of weather on the fire. Wildfire severity results from a combination of factors such as available fuels, physical setting, and weather. Climatic cycles with wet periods that create substantial fuels, followed by drought and heat, of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wire Rope
Steel wire rope (right hand lang lay) Wire rope is composed of as few as two solid, metal wires twisted into a helix that forms a composite ''rope'', in a pattern known as ''laid rope''. Larger diameter wire rope consists of multiple strands of such laid rope in a pattern known as ''cable laid''. Manufactured using an industrial machine known as a strander, the wires are fed through a series of barrels and spun into their final composite orientation. In stricter senses, the term ''wire rope'' refers to a diameter larger than , with smaller gauges designated cable or cords. Initially wrought iron wires were used, but today steel is the main material used for wire ropes. Historically, wire rope evolved from wrought iron chains, which had a record of mechanical failure. While flaws in chain links or solid steel bars can lead to catastrophic failure A catastrophic failure is a sudden and total failure from which recovery is impossible. Catastrophic failures often lead to cascadi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palisade
A palisade, sometimes called a stakewall or a paling, is typically a row of closely placed, high vertical standing tree trunks or wooden or iron stakes used as a fence for enclosure or as a defensive wall. Palisades can form a stockade. Etymology ''Palisade'' derives from ''pale'', from the Latin word ', meaning stake, specifically when used side by side to create a wood defensive wall. In turn, ''pālus'' derives from the Old Italic word ''palūts'', which may possibly derive from the Proto-Indo-European word ''pelh'', meaning pale or gray. It may be related to the Proto-Uralic word ''pil'me'' (uncertain meaning) or the word ''pilwe'', meaning cloud. (see wikt:pale#Etymology_2, 'pale', English: Etymology 2 on Wiktionary). Typical construction Typical construction consisted of small or mid-sized tree trunks aligned vertically, with as little free space in between as possible. The trunks were sharpened or pointed at the top, and were driven into the ground and sometimes rein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage
Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), work needed per unit of Electric charge, charge to move a positive Test particle#Electrostatics, test charge from the first point to the second point. In the SI unit, International System of Units (SI), the SI derived unit, derived unit for voltage is the ''volt'' (''V''). The voltage between points can be caused by the build-up of electric charge (e.g., a capacitor), and from an electromotive force (e.g., electromagnetic induction in a Electric generator, generator). On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect, and the thermoelectric effect. Since it is the difference in electric potential, it is a physical Scalar (physics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminum
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has a great affinity towards oxygen, passivation (chemistry), forming a protective layer of aluminium oxide, oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, magnetism, nonmagnetic, and ductility, ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the abundance of the chemical elements, 12th-most abundant element in the universe. The radioactive decay, radioactivity of aluminium-26, 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot-dip Galvanizing
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 . When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (Oxygen, O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2, CO2) to form zinc carbonate (Smithsonite, 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 ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
