|
Security Lighting
In the field of physical security, security lighting is lighting that intended to deter or detect intrusions or other criminal activity occurring on a property or site. It can also be used to increase a feeling of safety. Lighting is integral to crime prevention through environmental design. A 2019 study in New York City found that the provision of street lights, an important type of security lighting, resulted in a "36 percent reduction in nighttime outdoor index crimes." Planning considerations Security lighting to prevent intrusions may be counter-productive. Turning off lights halved the number of thefts and burglary in Övertorneå Sweden. "Outdoor Lighting and Crime, Part 2" by Barry Clark 2003, p. 18 and Figure 5 A test in West Sussex UK showed that adding all-night lighting in some areas made people there feel s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Security
Physical security describes security measures that are designed to deny unauthorized access to facilities, equipment and resources and to protect personnel and property from damage or harm (such as espionage, theft, or terrorist attacks). Physical security involves the use of multiple layers of interdependent systems that can include CCTV surveillance, security guards, protective barriers, locks, access control, perimeter intrusion detection, deterrent systems, fire protection, and other systems designed to protect persons and property. Overview Physical security systems for protected facilities are generally intended to: * deter potential intruders (e.g. warning signs, security lighting and perimeter markings); * detect intrusions and monitor/record intruders (e.g. intruder alarms and CCTV systems); and * trigger appropriate incident responses (e.g. by security guards and police). It is up to security designers, architects and analysts to balance security controls agains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Power Industry
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others. The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field. When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of posit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Astronomical Association
The British Astronomical Association (BAA) was formed in 1890 as a national body to support the UK's amateur astronomers. Throughout its history, the BAA has encouraged observers to make scientifically valuable observations, often in collaboration with professional colleagues. Among the BAA's first presidents was Walter Maunder, discoverer of the seventeenth century dearth in sunspots now known as the Maunder Minimum which he achieved by analysing historical observations. Later, this spirit of observing the night sky scientifically was championed by George Alcock, who discovered five comets and five novae using nothing more than a pair of binoculars. The BAA continues to contribute to the science of astronomy, even despite modern competition from space-based telescopes and highly automated professional observatories. Modern digital sensors, coupled with techniques such as lucky imaging, mean that even modest amateur equipment can rival what professional observatories could hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burglary
Burglary, also called breaking and entering and sometimes housebreaking, is the act of entering a building or other areas without permission, with the intention of committing a criminal offence. Usually that offence is theft, robbery or murder, but most jurisdictions include others within the ambit of burglary. To commit burglary is to ''burgle'', a term back-formed from the word ''burglar'', or to ''burglarize''. Etymology Sir Edward Coke (1552–1634) explains at the start of Chapter 14 in the third part of ''Institutes of the Lawes of England'' (pub. 1644), that the word ''Burglar'' ("''or the person that committeth burglary''"), is derived from the words ''burgh'' and ''laron'', meaning ''house-thieves''. A note indicates he relies on the ''Brooke's case'' for this definition. According to one textbook, the etymology originates from Anglo-Saxon or Old English, one of the Germanic languages. (Perhaps paraphrasing Sir Edward Coke:) "The word ''burglar'' comes from the two Ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Theft
Metal theft is "the theft of items for the value of their constituent metals". It usually increases when worldwide prices for scrap metal rise, as has happened dramatically due to rapid industrialization in India and China. Apart from precious metals like gold and silver, the metals most commonly stolen are non-ferrous metals such as copper, aluminium, brass, and bronze. However, even cast iron and steel are seeing higher rates of theft due to increased scrap metal prices. One defining characteristic of metal theft is the motivation. Whereas other items are generally stolen for their extrinsic value, items involved in metal theft are stolen for their intrinsic value as raw material or commodities. Thefts often have negative consequences much greater than the value of the metal stolen, such as the destruction of valuable statues, power interruptions, and the disruption of railway traffic. Items often stolen Anything made of metal has value as scrap metal, and can be stolen: * Man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South African Energy Crisis
The South African energy crisis is an ongoing period of widespread national blackouts of electricity supply. It began in the later months of 2007 and continues to the present. The South African government-owned national power utility and primary power generator, Eskom, and various parliamentarians attributed these rolling-blackouts to insufficient generation capacity. According to Eskom and government officials, the solution requires the construction of additional power stations and generators. Corruption and mismanagement of Eskom, most notably during the Jacob Zuma administration, have exacerbated this energy crisis; neglect by Eskom staff in addition to multiple acts of sabotage has also contributed to ongoing power supply problems. Background In a December 1998 report, analysts and leaders in Eskom and in the South African government predicted that Eskom would run out of electrical power reserves by 2007 unless action was taken to prevent it. To improve power supply and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Dark-Sky Association
The International Dark-Sky Association (IDA) is a United States-based non-profit organization incorporated in 1988 by founders David Crawford, a professional astronomer, and Tim Hunter, a physician/amateur astronomer. The mission of the IDA is "to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting." Light pollution is the result of outdoor lighting that is not properly shielded, allowing light shine into the eyes and night sky. Direct light that shines into the eyes is called glare, and light directed into the night sky above the horizon causes skyglow. Lighting can also cause light trespass when it enters areas where unwanted (e.g. a neighbor's yard and windows). IDA was the first organization in the dark-sky movement, and is currently the largest. Principal approach IDA's principal approach is to raise awareness about the value of dark, star-filled night skies and encourage their protection and restoration through e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photocell
Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response. Semiconductor-based photodetectors typically photo detector have a p–n junction that converts light photons into current. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy. Types Photodetectors may be classified by their mechanism for detection: * Photoemission or photoelectric effect: Photons cause electrons to transition from the conduction band of a material to free electrons in a vacuum or gas. * Thermal: Photons cause electrons to transition to mid-gap states then decay back to lower bands, inducing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Infrared Sensor
A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications. PIR sensors detect general movement, but do not give information on who or what moved. For that purpose, an imaging IR sensor is required. PIR sensors are commonly called simply "PIR", or sometimes "PID", for "passive infrared detector". The term ''passive'' refers to the fact that PIR devices do not radiate energy for detection purposes. They work entirely by detecting infrared radiation (radiant heat) emitted by or reflected from objects. Operating principles All objects with a temperature above absolute zero emit heat energy in the form of electromagnetic radiation. Usually this radiation isn't visible to the human eye because it radiates at infrared wavelengths, but it can be detected by ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-intensity Discharge Lamp
High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with noble gas and often also contains suitable metal or metal salts. The noble gas enables the arc's initial strike. Once the arc is started, it heats and evaporates the metallic admixture. Its presence in the arc plasma greatly increases the intensity of visible light produced by the arc for a given power input, as the metals have many emission spectral lines in the visible part of the spectrum. High-intensity discharge lamps are a type of arc lamp. Brand new high-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps, since a greater proportion of their radiation is visible light in contrast to infrared. However, the lumen output of HID lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Vapor Lamp
A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm. Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps are highly efficient electrical light sources, but their yellow light restricts applications to outdoor lighting, such as street lamps, where they are widely used. High-pressure sodium lamps emit a broader spectrum of light than the low-pressure lamps, but they still have poorer color rendering than other types of lamps. Low-pressure sodium lamps only give monochromatic yellow light and so inhibit color vision at night. Single ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap. They include the sodium-vapor lamp that is the gas-discharge lamp in street lighting. Development The low-pressure sodium arc discharge lamp was first made practical around 1920 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-intensity Discharge Lamp
High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with noble gas and often also contains suitable metal or metal salts. The noble gas enables the arc's initial strike. Once the arc is started, it heats and evaporates the metallic admixture. Its presence in the arc plasma greatly increases the intensity of visible light produced by the arc for a given power input, as the metals have many emission spectral lines in the visible part of the spectrum. High-intensity discharge lamps are a type of arc lamp. Brand new high-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps, since a greater proportion of their radiation is visible light in contrast to infrared. However, the lumen output of HID lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
