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Load Shifting
Load shifting is a dangerous phenomenon in water, air, and ground transportation where cargo shifts in a cargo vehicle. This causes the vehicle to tilt, which causes even more movement of the cargo, and further tilting, thereby creating a positive feedback loop. If not corrected, this will lead to severe tipping or even capsizing. Such a dangerous occurrence is prevented by active load management, avoiding high sea conditions for ships, and proper container/ bulkhead design. On a cargo airplane, a professional loadmaster is necessary to prevent the highly-dangerous phenomenon of load shifting. If cargo is not adequately secured, it can move during flight, and move the center of gravity outside of its safe operating limits, which will cause the aircraft to become uncontrollable or stall, and crash. Ships Ships are used to transport a majority of today's goods which is approximately 90% of all non bulk cargo. Ensuring that loads do not dangerously shift is part of boat design and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive Feedback
Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the magnitude of the perturbation. That is, ''A produces more of B which in turn produces more of A''.Keesing, R.M. (1981). Cultural anthropology: A contemporary perspective (2nd ed.) p.149. Sydney: Holt, Rinehard & Winston, Inc. In contrast, a system in which the results of a change act to reduce or counteract it has negative feedback. Both concepts play an important role in science and engineering, including biology, chemistry, and cybernetics. Mathematically, positive feedback is defined as a positive loop gain around a closed loop of cause and effect. That is, positive feedback is Phase (waves), in phase with the input, in the sense that it adds to make the input larger. Positive feedback tends to cause Control theory#Stability, system i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elsevier
Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell'', the ScienceDirect collection of electronic journals, '' Trends'', the '' Current Opinion'' series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services also include digital tools for data management, instruction, research analytics and assessment. Elsevier is part of the RELX Group (known until 2015 as Reed Elsevier), a publicly traded company. According to RELX reports, in 2021 Elsevier published more than 600,000 articles annually in over 2,700 journals; as of 2018 its archives contained over 17 million documents and 40,000 e-books, with over one billion annual downloads. Researchers have criticized Elsevier for its high profit marg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1981 Pushkin Tu-104 Crash
On 7 February 1981, a Tupolev Tu-104 passenger jet crashed during take off from Pushkin Airport near Leningrad (today's Saint Petersburg), Russia, resulting in the death of all 50 people on board, including 28 high-ranking Soviet military personnel. The official investigation concluded that the aircraft was improperly loaded. Accident At 18:00 local time, the Tu-104 lined up on runway 21 and commenced its take-off run during snowing weather conditions. After rotation, the aircraft pitched up beyond normal take-off attitude, and eight seconds after lift off, at an altitude above ground level of , the Tupolev stalled and entered a right bank. The aircraft continued to roll right until it struck the ground from the departure end of the runway, crashing nearly inverted and bursting into flames, killing 49 of the 50 people on board. One person in the cockpit was ejected from the nose of the aircraft, and was found alive in the snow not far from the crash site, but died on the way to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Airlines Flight 102
National Airlines Flight 102 was a cargo flight operated by National Airlines (N8), National Airlines between Camp Bastion in Afghanistan and Al Maktoum Airport in Dubai, with a refueling stop at Bagram Airfield, Afghanistan. On 29 April 2013, the Boeing 747-400 operating the flight crashed moments after taking off from Bagram, killing all seven people on board. The subsequent investigation concluded that improperly secured cargo broke free during the take-off and Load shifting, rolled to the back of the cargo hold, crashing through the rear pressure bulkhead and disabling the rear flight control systems. This rendered the aircraft uncontrollable, making recovery from a Stall (fluid dynamics), stall, brought on by the damaged rear flight control systems ending up stuck in a pitch-up attitude, impossible. Accident At the time of the crash, the airline had been operating between Camp Bastion and Dubai for a month. The accident flight had originated in Camp Bastion, where it had b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Department Of Transportation
The United States Department of Transportation (USDOT or DOT) is one of the executive departments of the U.S. federal government. It is headed by the secretary of transportation, who reports directly to the President of the United States and is a member of the president's Cabinet. The department's mission is "to develop and coordinate policies that will provide an efficient and economical national transportation system, with due regard for need, the environment, and the national defense." History Prior to the creation of the Department of Transportation, its functions were administered by the under secretary of commerce for transportation. In 1965, Najeeb Halaby, administrator of the Federal Aviation Agency (predecessor to the Federal Aviation Administration, FAA), suggested to President Lyndon B. Johnson that transportation be elevated to a cabinet-level post, and that the FAA be folded into the DOT. It was established by Congress in the Department of Transportation Act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weight Control And Balance Of An Aircraft
In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a vector quantity, the gravitational force acting on the object. Others define weight as a scalar quantity, the magnitude of the gravitational force. Yet others define it as the magnitude of the reaction force exerted on a body by mechanisms that counteract the effects of gravity: the weight is the quantity that is measured by, for example, a spring scale. Thus, in a state of free fall, the weight would be zero. In this sense of weight, terrestrial objects can be weightless: ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, would be weightless. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, and ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Maritime Organization
The International Maritime Organization (IMO, French: ''Organisation maritime internationale'') is a specialised agency of the United Nations responsible for regulating shipping. The IMO was established following agreement at a UN conference held in Geneva in 1948 and the IMO came into existence ten years later, meeting for the first time in 1959. Headquartered in London, United Kingdom, IMO currently has 175 Member States and three Associate Members. The IMO's primary purpose is to develop and maintain a comprehensive regulatory framework for shipping and its remit today includes maritime safety, environmental concerns, legal matters, technical co-operation, maritime security and the efficiency of shipping. IMO is governed by an assembly of members which meets every two years. Its finance and organization is administered by a council of 40 members elected from the assembly. The work of IMO is conducted through five committees and these are supported by technical subcommitte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SOLAS Convention
The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty that sets minimum safety standards in the construction, equipment and operation of merchant ships. The International Maritime Organization convention requires signatory flag states to ensure that ships flagged by them comply with at least these standards. The current version of SOLAS is the 1974 version, known as SOLAS 1974, which came into force on 25 May 1980. , SOLAS 1974 has 167 contracting states, which flag about 99% of merchant ships around the world in terms of gross tonnage. SOLAS in its successive forms is generally regarded as the most important of all international treaties concerning the safety of merchant ships. Signatories The non-parties to SOLAS 1974 include numerous landlocked countries (for obvious reasons), as well as El Salvador, Micronesia and East Timor. Some others including Bolivia, Lebanon and Sri Lanka, all considered flag of convenience states, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bilge
The bilge of a ship or boat is the part of the hull that would rest on the ground if the vessel were unsupported by water. The "turn of the bilge" is the transition from the bottom of a hull to the sides of a hull. Internally, the bilges (usually used in the plural in this context) is the lowest compartment on a ship or seaplane, on either side of the keel and (in a traditional wooden vessel) between the floors. The first known use of the word is from 1513. Bilge water The word is sometimes also used to describe the water that collects in this area. Water that does not drain off the side of the deck or through a hole in the hull, typically via a scupper, drains down into the ship into the bilge. This water may be from rough seas, rain, leaks in the hull or stuffing box, or other interior spillage. The collected water must be pumped out to prevent the bilge from becoming too full and threatening to sink the ship. Bilge water can be found aboard almost every vessel. Depending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Surface Effect
The free surface effect is a mechanism which can cause a watercraft to become unstable and capsize. It refers to the tendency of liquids — and of unbound aggregates of small solid objects, like seeds, gravel, or crushed ore, whose behavior approximates that of liquids — to move in response to changes in the attitude of a craft's cargo holds, decks, or liquid tanks in reaction to operator-induced motions (or sea states caused by waves and wind acting upon the craft). When referring to the free surface effect, the condition of a tank that is not full is described as a "slack tank", while a full tank is "pressed up". Stability and equilibrium In a normally loaded vessel any rolling from perpendicular is countered by a righting moment generated from the increased volume of water displaced by the hull on the lowered side. This assumes the center of gravity of the vessel is relatively constant. If a moving mass inside the vessel moves in the direction of the roll, this counters t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ScienceDirect
ScienceDirect is a website which provides access to a large bibliographic database of scientific and medical publications of the Dutch publisher Elsevier. It hosts over 18 million pieces of content from more than 4,000 academic journals and 30,000 e-books of this publisher. The access to the full-text requires subscription, while the bibliographic metadata is free to read. ScienceDirect is operated by Elsevier. It was launched in March 1997. Usage The journals are grouped into four main sections: ''Physical Sciences and Engineering'', ''Life Sciences'', ''Health Sciences'', and ''Social Sciences and Humanities''. Article abstracts are freely available, and access to their full texts (in PDF and, for newer publications, also HTML) generally requires a subscription or pay-per-view purchase unless the content is freely available in open access. Subscriptions to the overall offering hosted on ScienceDirect, rather than to specific titles it carries, are usually acquired through a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Center Of Mass
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may be applied to cause a linear acceleration without an angular acceleration. Calculations in mechanics are often simplified when formulated with respect to the center of mass. It is a hypothetical point where the entire mass of an object may be assumed to be concentrated to visualise its motion. In other words, the center of mass is the particle equivalent of a given object for application of Newton's laws of motion. In the case of a single rigid body, the center of mass is fixed in relation to the body, and if the body has uniform density, it will be located at the centroid. The center of mass may be located outside the physical body, as is sometimes the case for hollow or open-shaped objects, such as a horseshoe. In the case of a dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
