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Aethalometer Interior
An aethalometer is an instrument for measuring the concentration of optically absorbing (‘black’) suspended particulates in a gas colloid stream; commonly visualized as smoke or haze, often seen in ambient air under polluted conditions. The word aethalometer is derived from the Classical Greek verb ''aethaloun'', meaning "to blacken with soot". The aethalometer, a device used for measuring black carbon in atmospheric aerosols, was initially deployed in 1980 and was first commercialized by Magee Scientific. Principle of operation The gas stream (frequently ambient air) passes through a filter material which traps the suspended particulates, creating a deposit of increasing density. A light beam projected through the deposit is attenuated by those particles which are absorbing (‘black’) rather than scattering (‘white’). Measurements are made at successive regular time intervals. The increase in attenuation from one measurement to the next is proportional to the incr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aethalometer Exterior
An aethalometer is an instrument for measuring the concentration of optically absorbing (‘black’) Suspension (chemistry), suspended particulates in a gas colloid stream; commonly visualized as smoke or haze, often seen in ambient air under polluted conditions. The word aethalometer is derived from the Classical Greek verb ''aethaloun'', meaning "to blacken with soot". The aethalometer, a device used for measuring black carbon in atmospheric aerosols, was initially deployed in 1980 and was first commercialized by Magee Scientific. Principle of operation The gas stream (frequently ambient air) passes through a Filter paper, filter material which traps the suspended particulates, creating a deposit of increasing density. A light beam projected through the deposit is Attenuation, attenuated by those particles which are Light absorption, absorbing (‘black’) rather than Light scattering, scattering (‘white’). Measurements are made at successive regular time intervals. The i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog-to-digital Converter
In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a Digital signal (signal processing), digital signal. An ADC may also provide an isolated measurement such as an electronic device that converts an analog input voltage or Electric current, current to a digital number representing the magnitude of the voltage or current. Typically the digital output is a two's complement binary number that is proportional to the input, but there are other possibilities. There are several ADC hardware architecture, architectures. Due to the complexity and the need for precisely matched electronic component, components, all but the most specialized ADCs are implemented as integrated circuits (ICs). These typically take the form of metal–oxide–semiconductor (MOS) mixed-signal integrated circuit chips that integrate both Analogue electronics, anal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aethalometer Interior
An aethalometer is an instrument for measuring the concentration of optically absorbing (‘black’) suspended particulates in a gas colloid stream; commonly visualized as smoke or haze, often seen in ambient air under polluted conditions. The word aethalometer is derived from the Classical Greek verb ''aethaloun'', meaning "to blacken with soot". The aethalometer, a device used for measuring black carbon in atmospheric aerosols, was initially deployed in 1980 and was first commercialized by Magee Scientific. Principle of operation The gas stream (frequently ambient air) passes through a filter material which traps the suspended particulates, creating a deposit of increasing density. A light beam projected through the deposit is attenuated by those particles which are absorbing (‘black’) rather than scattering (‘white’). Measurements are made at successive regular time intervals. The increase in attenuation from one measurement to the next is proportional to the incr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Quality
Air pollution is the presence of substances in the Atmosphere of Earth, air that are harmful to humans, other living beings or the environment. Pollutants can be Gas, gases like Ground-level ozone, ozone or nitrogen oxides or small particles like soot and dust. It affects both outdoor air and indoor air. Natural sources of air pollution include Wildfire, wildfires, Dust storm, dust storms, and Volcanic eruption, volcanic eruptions. Indoor air pollution is often Energy poverty and cooking, caused by the use of biomass (e.g. wood) for cooking and heating. Outdoor air pollution comes from some industrial processes, the burning of Fossil fuel, fossil fuels for electricity and transport, waste management and agriculture. Many of the contributors of local air pollution, especially the burning of fossil fuels, also cause greenhouse gas emissions that cause climate change, global warming. Air pollution causes around 7 or 8 million deaths each year. It is a significant risk factor for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rack-mount
A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or ''ears'' that protrude from each side of the equipment, allowing the module to be fastened to the rack frame with screws or bolts. Common uses include computer servers, telecommunications equipment and networking hardware, audiovisual production gear, professional audio equipment, and scientific equipment. Overview and history Equipment designed to be placed in a rack is typically described as rack-mount, rack-mount instrument, a rack-mounted system, a rack-mount chassis, subrack, rack cabinet, rack-mountable, or occasionally simply shelf. The height of the electronic modules is also standardized as multiples of or one rack unit or U (less commonly RU). The industry-standard rack cabinet is 42U tall; however, many data centers have racks taller than this. The term relay rack app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Environmental Protection Agency
The Environmental Protection Agency (EPA) is an independent agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on December 2, 1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its administrator, who is appointed by the president and approved by the Senate. The current administrator is Lee Zeldin. The EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D.C. There are regional offices for each of the agency's ten regions, as well as 27 laboratories around the country. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of environmental laws, in consultation w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Congress
The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, U.S. House of Representatives, and an Upper house, upper body, the United States Senate, U.S. Senate. They both meet in the United States Capitol in Washington, D.C. Members of Congress are chosen through direct election, though vacancies in the Senate may be filled by a Governor (United States), governor's appointment. Congress has a total of 535 voting members, a figure which includes 100 United States senators, senators and 435 List of current members of the United States House of Representatives, representatives; the House of Representatives has 6 additional Non-voting members of the United States House of Representatives, non-voting members. The vice president of the United States, as President of the Senate, has a vote in the Senate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Change In The Arctic
Due to climate change in the Arctic, this polar region is expected to become "profoundly different" by 2050. The speed of change is "among the highest in the world", with the rate of warming being 3-4 times faster than the global average. This warming has already resulted in the profound Arctic sea ice decline, the accelerating melting of the Greenland ice sheet and the thawing of the permafrost Permafrost () is soil or underwater sediment which continuously remains below for two years or more; the oldest permafrost has been continuously frozen for around 700,000 years. Whilst the shallowest permafrost has a vertical extent of below ... landscape. These ongoing transformations are expected to be irreversible for centuries or even millennia. Natural life in the Arctic is affected greatly. As the tundra warms, its soil becomes more hospitable to earthworms and larger plants, and the taiga, boreal forests spread to the north - yet this also makes the landscape more prone to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures is Scientific consensus on climate change, driven by human activities, especially fossil fuel burning since the Industrial Revolution. Fossil fuel use, Deforestation and climate change, deforestation, and some Greenhouse gas emissions from agriculture, agricultural and Environmental impact of concrete, industrial practices release greenhouse gases. These gases greenhouse effect, absorb some of the heat that the Earth Thermal radiation, radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary gas driving global warming, Carbon dioxide in Earth's atmosphere, has increased in concentratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diesel Exhaust
Diesel exhaust is the exhaust gas produced by a diesel engine, plus any contained particulates. Its composition may vary with the fuel type, rate of consumption or speed of engine operation (e.g., idling or at speed or under load), and whether the engine is in an on-road vehicle, farm vehicle, locomotive, marine vessel, or stationary generator or other application. Diesel exhaust causes lung cancer and other diseases such as asthma, and many premature deaths. Methods exist to reduce nitrogen oxides (NOx) and particulate matter (PM) in the exhaust. Some countries have set a date to stop selling diesel vehicles, and some city centres will ban diesel cars. Composition The primary products of petroleum fuel combustion in air are carbon dioxide, water, and nitrogen. The other components exist primarily from incomplete combustion and pyrosynthesis. While the distribution of the individual components of raw (untreated) diesel exhaust varies depending on factors like load, engi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long-range Transport
Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released. The effect of POPs on human and environmental health was discussed, with intention to eliminate or severely restrict their production, by the international community at the Stockholm Convention on Persistent Organic Pollutants in 2001. Most POPs are pesticides or insecticides, and some are also solvents, pharmaceuticals, and industrial chemicals. Although some POPs arise naturally (e.g. from volcanoes), most are man-made. The "dirty dozen" POPs identified by the Stockholm Convention include aldrin, chlordane, dieldrin, endrin, heptachlor, HCB, mirex, toxaphene, PCBs, DDT, dioxins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soot
Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. Soot is considered a hazardous substance with carcinogenic properties. Most broadly, the term includes all the particulate matter produced by this process, including black carbon and residual pyrolysed fuel particles such as coal, cenospheres, charred wood, and petroleum coke classified as cokes or char. It can include polycyclic aromatic hydrocarbons and heavy metals like mercury. Soot causes various types of cancer and lung disease. Terminology Definition Among scientists, exact definitions for soot vary, depending partly on their field. For example, atmospheric scientists may use a different definition compared to toxicologists. Soot's definition can also vary across time, and from paper to paper even among scientists in the same field. A common feature of the definitions is that soot is composed largely of carbon based particles resulting from the incomplete burni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
