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Topic Review
Coppermine Expedition of 1819–22
The Coppermine Expedition of 1819–1822 had as its goal the exploration of the northern coast of Canada , which was accessed by way of the Coppermine River. The British expedition was organised by the Royal Navy as part of its attempt to discover and map the Northwest Passage. It was the first of three Arctic expeditions to be led by John Franklin, and also included George Back and Dr. John Richardson, both of whom would become notable Arctic explorers in their own right. The expedition was plagued by poor planning, bad luck and unreliable allies. The expected assistance from the local fur trading companies and native peoples was less forthcoming than expected, and the dysfunctional supply line, coupled with unusually harsh weather and the resulting absence of game, meant that the explorers were never far from starvation. Eventually the Arctic coast was reached, but barely 500 mi (800 km) had been explored before the exhaustion of the party's supplies and the onset of winter forced it to turn back. The expedition made a desperate retreat across uncharted territory in a state of starvation, often with nothing more than lichen to eat. Eleven of the twenty-strong party died amid accusations of murder and cannibalism before the survivors were rescued by people of the Yellowknives First Nation, who had previously given them up for dead. In the aftermath of the expedition, Franklin was much criticised by local fur traders for his haphazard planning and failure to adapt to the circumstances he faced, but in Britain he was received as a hero, and fêted for the courage he had shown in extreme adversity. The expedition captured the public imagination, and in reference to a desperate measure he took while starving, he became known as "the man who ate his boots".
  • 448
  • 24 Oct 2022
Topic Review
Neolithic Subpluvial
The Neolithic Subpluvial, or the Holocene Wet Phase, was an extended period (from about 7500–7000 BCE to about 3500–3000 BCE) of wet and rainy conditions in the climate history of northern Africa. It was both preceded and followed by much drier periods. The Neolithic Subpluvial was the most recent of a number of periods of "Wet Sahara" or "Green Sahara", during which the Sahara region was much moister and supported a richer biota and human population than the present-day desert.
  • 1.3K
  • 24 Oct 2022
Topic Review
Coal Assay
Coal analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.
  • 406
  • 24 Oct 2022
Topic Review
Chemical Waste
Chemical waste is waste , that is made from chemicals that are mostly produced by large factories. Chemical waste can damage , the environment and cause health problems and as such may fall under regulations such as COSHH in the United Kingdom or the Clean Water Act and Resource Conservation and Recovery Act in the United States . In the U.S., the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA), as well as state and local regulations also regulate chemical use and disposal. The disposal and handling of radioactive waste is a particular focus for regulatory bodies due to the environmental and health risks of radiation and the challenges of safe disposal. Chemical waste may or may not be classed as hazardous waste. A chemical hazardous waste is a solid, liquid, or gaseous material that displays either a "Hazardous Characteristic" or is specifically "listed" by name as hazardous waste. There are four characteristics chemical wastes may have to be considered hazardous. These are ignitability, corrosivity, reactivity, and toxicity. This type of hazardous waste must be categorized as to its identity, constituents, and hazards so that it may be safely handled and managed. Chemical waste is a broad term and encompasses many types of materials. The Material Safety Data Sheet (MSDS), Product data sheet or Label can provide a list of constituents. These sources should state whether this chemical waste is a waste that needs special disposal.
  • 1.6K
  • 24 Oct 2022
Topic Review
Image-Based Obstacle Detection Methods
Mobile robots lack a driver or a pilot and, thus, should be able to detect obstacles autonomously. These various image-based obstacle detection techniques include Unmanned Surface Vehicles (USVs), Unmanned Aerial Vehicles (UAVs), and Micro Aerial Vehicles (MAVs). The techniques were divided into monocular and stereo. The former uses a single camera, while the latter makes use of images taken by two synchronised cameras. Monocular obstacle detection methods are discussed in appearance-based, motion-based, depth-based, and expansion-based categories. Monocular obstacle detection approaches have simple, fast, and straightforward computations. Thus, they are more suited for robots like MAVs and compact UAVs, which usually are small and have limited processing power. On the other hand, stereo-based methods use pair(s) of synchronised cameras to generate a real-time 3D map from the surrounding objects to locate the obstacles. Stereo-based approaches have been classified into Inverse Perspective Mapping (IPM)-based and disparity histogram-based methods. Whether aerial or terrestrial, disparity histogram-based methods suffer from common problems: computational complexity, sensitivity to illumination changes, and the need for accurate camera calibration, especially when implemented on small robots.
  • 1.4K
  • 24 Oct 2022
Topic Review
Enhanced 9-1-1
Enhanced 911, E-911 or E911 is a system used in North America to automatically provide the caller's location to 911 dispatchers. 911 is the universal emergency telephone number in the region. In the European Union, a similar system exists known as E112 (where 112 is the emergency access number) and known as eCall when called by a vehicle. An incoming 911 call is routed to a Public Safety Answering Point (PSAP), which is a call center operated by the local government. At the PSAP, the call is answered by a specially trained official known as a 9-1-1 dispatcher. The dispatcher's computer receives information from the telephone company about the physical address (for landlines) or geographic coordinates (for wireless) of the caller. This information is used to dispatch police, fire, medical, and other services as needed.
  • 400
  • 24 Oct 2022
Topic Review
Steamboat Springs (Nevada)
Steamboat Springs is a small volcanic field of rhyolitic lava domes and flows in western Nevada, located south of Reno. There is extensive geothermal activity in the area, including numerous hot springs, steam vents, and fumaroles. The residential portions of this area, located mostly east of Steamboat Creek and south of modern-day SR 341, are now known simply as Steamboat. The state of Nevada has a Steamboat Springs Historical Marker (#198) situated along the eastern shoulder of the busy Carson–Reno Highway (US 395 Alt.), approximately 1.65 miles (2.66 km) south of the Mount Rose Junction (the intersection with SR 341 and SR 431). There were once several mineral spas operating here along Steamboat Creek, with at least one still in business called Steamboat Hot Springs Healing Center & Spa. The water from the springs contains many minerals including: calcium carbonate, magnesium, sodium sulfate, carbon dioxide, lithia, soda and silica.
  • 341
  • 24 Oct 2022
Topic Review
Dry Permanent Magnetic Separator
Dry magnetic separation is a technology that sorts magnetic minerals from gangue using air as the medium instead of water. When raw ore is fed to the magnetic separator, the magnetic particles are subjected to magnetic force due to the nonuniform magnetic field. When the magnetic force exceeds the competitive force (i.e., gravity and fluid drag force), the particles are captured on or attracted towards the surface of the drum and consequently enter the magnetic product. Meanwhile, the gangue or poor intergrowth particles are not subjected to magnetic force and are separated into the non-magnetic product under the action of competitive force. In other words, magnetic minerals and gangue have different trajectories in a magnetic separator, thereby achieving the purpose of separation. Dry magnetic separation has been recently adopted by plants to cope with cost and environmental pressures.
  • 2.7K
  • 24 Oct 2022
Topic Review
Sulfide Minerals
The sulfide minerals are a class of minerals containing sulfide (S2−) or persulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulfarsenides and the sulfosalts. Sulfide minerals are inorganic compounds.
  • 618
  • 24 Oct 2022
Topic Review
Ordovician–Silurian Extinction Events
The Ordovician–Silurian extinction events, when combined, are the second-largest of the five major extinction events in Earth's history in terms of percentage of genera that became extinct. This event greatly affected marine communities, which caused the disappearance of one third of all brachiopod and bryozoan families, and further numerous groups of conodonts, trilobites, and graptolites. The Ordovician–Silurian extinction occurred during the Hirnantian stage of the Ordovician Period and the subsequent Rhuddanian stage of the Silurian Period. The last event, the Late Ordovician mass extinction (LOME), is dated in the interval of 455 to 430 million years ago, lasting from the Middle Ordovician to Early Silurian, thus including the extinction period. This event was the first of the big five Phanerozoic events and was the first to significantly affect animal-based communities. In May 2020, geologists reported that this mass extinction, the Late Ordovician mass extinction, 445 million years ago, may have been the result of global warming. Almost all major taxonomic groups were affected during this extinction event. Extinction was global during this period, eliminating 49–60% of marine genera and nearly 85% of marine species. Brachiopods, bivalves, echinoderms, bryozoans and corals were particularly affected. Before the late Ordovician cooling, temperatures were relatively warm and it is the suddenness of the climate changes and the elimination of habitats due to sea-level fall that are believed to have precipitated the extinctions. The falling sea level disrupted or eliminated habitats along the continental shelves. Evidence for the glaciation was found through deposits in the Sahara Desert. A combination of lowering of sea level and glacially driven cooling were likely driving agents for the Ordovician mass extinction.
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  • 23 Oct 2022
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