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Topic Review
BMW 3 Series (E46)
The BMW E46 is the fourth generation of the BMW 3 Series, which was produced from 1997 to 2006. The body styles of the range are: All-wheel drive, last available in the E30 3 Series, was reintroduced for the E46 on the 325xi, 330xi and 330xd models. The E46 was the first 3 Series to be available with an engine using Valvetronic (variable valve lift). Various electronic features were also introduced to the 3 Series in the E46 generation, including satellite navigation, electronic brake-force distribution, rain-sensing wipers and LED tail-lights. Following the introduction of the E90 3 Series sedans in late 2004, the E46 began to be phased out. However the E46 coupé and convertible body styles remained in production until 2006. The E46 M3 is powered by the S54 straight-six engine with either a 6-speed manual or a 6-speed SMG-II transmission. The M3 was introduced in late 2000 and was produced in coupé and convertible body styles only.
  • 46.4K
  • 03 Nov 2022
Topic Review
Shaft Mining
Shaft mining or shaft sinking is excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom. Shallow shafts, typically sunk for civil engineering projects differ greatly in execution method from deep shafts, typically sunk for mining projects. When the top of the excavation is the ground surface, it is referred to as a shaft; when the top of the excavation is underground, it is called a winze or a sub-shaft. Small shafts may be excavated upwards from within an existing mine as long as there is access at the bottom, in which case they are called Raises. A shaft may be either vertical or inclined (between 45 and 90 degrees to the horizontal), although most modern mine shafts are vertical. If access exists at the bottom of the proposed shaft and ground conditions allow then raise boring may be used to excavate the shaft from the bottom up, such shafts are called borehole shafts. Shaft sinking is one of the most difficult of all development methods: restricted space, gravity, groundwater and specialized procedures make the task quite formidable. Historically mine shaft sinking has been among the most dangerous of all the mining occupations and the preserve of mining contractors called sinkers. Today shaft sinking contractors are concentrated in Canada , Germany and South Africa .
  • 19.8K
  • 17 Nov 2022
Topic Review
Mercedes-Benz CLS-Class (W219)
The C219 Mercedes-Benz CLS-Class is the first generation of the CLS-Class range of four-door coupe features a fastback body style by Mercedes-Benz, and was produced between 2004 and 2010. The CLS-Class has only four seats and is marketed by Mercedes as a four-door coupé. For this reason, in Germany and in whole Europe the model code name is C219 while in US the CLS is more commonly named as W219 model. It was the first model globally to introduce this four-door coupe style and VW followed with the Volkswagen CC model in 2008. The car is less practical than the W211 E-Class that it is based on, with less legroom, headroom, and boot space. The CLS-Class is priced above the E-Class, but below the S-Class in the Mercedes model range. It was replaced by the Mercedes-Benz CLS-Class (W218) in 2011.
  • 13.9K
  • 04 Nov 2022
Topic Review
Overhead Camshaft
Overhead camshaft, commonly abbreviated to OHC, is a valvetrain configuration which places the camshaft of an internal combustion engine of the reciprocating type within the cylinder heads ("above" the pistons and combustion chambers) and drives the valves or lifters in a more direct manner compared with overhead valves (OHV) and pushrods.
  • 12.7K
  • 21 Nov 2022
Topic Review
Jet Engine Thrust
The familiar explanation for jet thrust is a "black box" description which only looks at what goes into the jet engine, air and fuel, and what comes out, exhaust gas and an unbalanced force. This force, called thrust, is the sum of the momentum difference between entry and exit and any unbalanced pressure force between entry and exit, as explained in "Thrust calculation". As an example, an early turbojet, the Bristol Olympus Mk. 101, had a momentum thrust of 9300 lb. and a pressure thrust of 1800 lb. giving a total of 11,100 lb. Looking inside the "black box" shows that the thrust results from all the unbalanced momentum and pressure forces created within the engine itself. These forces, some forwards and some rearwards, are across all the internal parts, both stationary and rotating, such as ducts, compressors, etc., which are in the primary gas flow which flows through the engine from front to rear. The algebraic sum of all these forces is delivered to the airframe for propulsion. "Flight" gives examples of these internal forces for two early jet engines, the Rolls-Royce Avon Ra.14 and the de Havilland Goblin
  • 12.4K
  • 23 Nov 2022
Topic Review
Fuel Economy in Aircraft
The fuel economy in aircraft is the measure of the transport energy efficiency of aircraft. Efficiency is increased with better aerodynamics and by reducing weight, and with improved engine BSFC and propulsive efficiency or TSFC. Endurance and range can be maximized with the optimum airspeed, and economy is better at optimum altitudes, usually higher. An airline efficiency depends on its fleet fuel burn, seating density, air cargo and passenger load factor, while operational procedures like maintenance and routing can save fuel. Average fuel burn of new aircraft fell 45% from 1968 to 2014, a compounded annual reduction 1.3% with a variable reduction rate. In 2018, CO₂ emissions totalled 747 million tonnes for passenger transport, for 8.5 trillion revenue passenger kilometres (RPK), giving an average of 88 gram CO₂ per RPK. A 88 gCO₂/km represents 28 g of fuel per km, or a 3.5 L/100 km (67 mpg‑US) fuel consumption. New technology can reduce engine fuel consumption, like higher pressure and bypass ratios, geared turbofans, open rotors, hybrid electric or fully electric propulsion; and airframe efficiency with retrofits, better materials and systems and advanced aerodynamics.
  • 12.4K
  • 01 Nov 2022
Topic Review
Longitudinal Static Stability
In flight dynamics, longitudinal static stability is the stability of an aircraft in the longitudinal, or pitching, plane under steady flight conditions. This characteristic is important in determining whether a human pilot will be able to control the aircraft in the pitching plane without requiring excessive attention or excessive strength.
  • 11.7K
  • 20 Oct 2022
Topic Review
V-twin Engine
A V-twin engine, also called a V2 engine, is a two-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration. Although widely associated with motorcycles (installed either transversely or longitudinally), V-twin engines have also been used for industrial engines and in several small cars. The V-twin design dates back to the late 1880s.
  • 11.1K
  • 21 Oct 2022
Topic Review
Standard Conditions for Temperature and Pressure
Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted standards. Other organizations have established a variety of alternative definitions for their standard reference conditions. In chemistry, IUPAC changed the definition of standard temperature and pressure in 1982: STP should not be confused with the standard state commonly used in thermodynamic evaluations of the Gibbs energy of a reaction. NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa). This standard is also called normal temperature and pressure (abbreviated as NTP). These stated values of STP used by NIST have not been verified and require a source. However, values cited in Modern Thermodynamics with Statistical Mechanics by Carl S. Helrich and A Guide to the NIST Chemistry WebBook by Peter J. Linstrom suggest a common STP in use by NIST for thermodynamic experiments is 298.15 K (25°C, 77°F) and 1 bar (14.5038 psi, 100 kPa). The International Standard Metric Conditions for natural gas and similar fluids are 288.15 K (15.00 °C; 59.00 °F) and 101.325 kPa. In industry and commerce, standard conditions for temperature and pressure are often necessary to define the standard reference conditions to express the volumes of gases and liquids and related quantities such as the rate of volumetric flow (the volumes of gases vary significantly with temperature and pressure): standard cubic meters per second (Sm3/s), and normal cubic meters per second (Nm3/s). However, many technical publications (books, journals, advertisements for equipment and machinery) simply state "standard conditions" without specifying them; often substituting the term with older "normal conditions", or "NC". In special cases this can lead to confusion and errors. Good practice always incorporates the reference conditions of temperature and pressure. If not stated, some room environment conditions are supposed, close to 1 atm pressure, 293 K (20 °C), and 0% humidity.
  • 10.8K
  • 09 Nov 2022
Topic Review
Cigarette Lighter Receptacle
The cigarette lighter receptacle (also called a cigar lighter receptacle or cigar lighter socket) in an automobile was initially designed to power an electrically heated cigarette lighter, but became a de facto standard DC connector to supply electrical power for portable accessories used in or near an automobile. While the cigarette lighter receptacle is a common feature of automobiles and trucks, as a DC power connector it has the disadvantages of bulkiness, relatively low current rating, and poor contact reliability. Examples of devices that can be operated from a cigarette lighter receptacle include lights, fans, beverage heating devices, and small motorized tools such as air compressors for inflating tires. Many portable electronic devices such as music players or mobile telephones use a cigarette lighter receptacle to recharge their internal batteries or to directly operate from the vehicle electrical system. Adapters for electronic devices may change voltage to be compatible with the supplied device. Devices that require alternating-current mains electricity can be operated with a plug-in inverter. Automobiles may provide several 12 V receptacles that are intended only to operate electrical accessories, and which cannot be used with a cigarette lighter. Car manufacturers may offer a cigarette lighter only as an optional extra-cost accessory. Usually, only one 12 V receptacle near the driver will be able to accommodate an actual cigarette lighter, with other receptacles designated as "12 V auxiliary power outlets" which are not physically able to power a lighter.
  • 10.1K
  • 24 Oct 2022
Topic Review
List of ASTM International Standards (D)
This is a list of ASTM International standards for "Materials for Specific Applications".
  • 9.3K
  • 11 Oct 2022
Topic Review
Straight-Six Engine
The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is an internal combustion engine, with six cylinders mounted in a straight line along the crankcase with all the pistons driving a common crankshaft (straight engine). The bank of cylinders may be oriented at any angle, and where the bank is inclined away from the vertical, the engine is sometimes called a slant-six (although this is also a Chrysler-specific design). The straight-six layout is the simplest engine layout that possesses both primary and secondary mechanical engine balance, resulting in much less vibration than engines with fewer cylinders.
  • 8.4K
  • 15 Nov 2022
Topic Review
GAZ Tigr
The GAZ Tigr (Russian: Тигр and English: Tiger) is a Russia n 4x4, multipurpose, all-terrain infantry mobility vehicle manufactured by GAZ, first delivered to the Russian Army in 2006. Primarily used by the Russian Federation's armed forces, it is also used by numerous other countries.
  • 7.6K
  • 26 Oct 2022
Topic Review
List of DCS Modules
The below list includes all standalone products (commonly known as "modules") in Digital Combat Simulator, an air combat video game developed by Russian developer Eagle Dynamics. Fighter aircraft, helicopters and trainer aircraft modules can be flown by human players and artificial intelligence. Aircraft carriers, tanker aircraft and airborne early warning and control aircraft cannot be operated by human players.
  • 7.1K
  • 14 Nov 2022
Topic Review
DeLorean DMC-12
The DeLorean DMC-12 (commonly referred to simply as "the DeLorean", as it was the only model ever produced by the company) is a sports car originally manufactured by John DeLorean's DeLorean Motor Company for the American market from 1981 to 1983. The car features gull-wing doors and an innovative fiberglass body structure with a steel backbone chassis, along with external brushed stainless-steel body panels. It became widely known and iconic for its appearance, and because a modified DMC-12 was immortalized as the DeLorean time machine in the Back to the Future media franchise. The first prototype appeared in October 1976. Production officially began in 1981 in Dunmurry, a suburb of southwest Belfast, Northern Ireland, where the first DMC-12 rolled off the production line on January 21. Over the course of production, several features of the car were changed, such as the hood style, wheels, and interior. About 9,000 DMC-12s were made before production halted in early 1983. The DMC-12 was the only model produced by the company, which was later liquidated as the US car market went through its largest slump since the 1930s. In 2007, about 6,500 DeLorean Motor cars were thought to still exist. In 1995, Stephen Wynne, a British entrepreneur from Liverpool, created a separate company based in Texas using the "DeLorean Motor Company" name. Wynne acquired the trademark on the stylized "DMC" logo shortly thereafter, along with the remaining parts inventory of the original DeLorean Motor Company. The company builds new cars at its suburban Humble, Texas location from new old stock (NOS) parts, original equipment manufacturer (OEM), and reproduction parts on a "made to order" basis using existing vehicle identification number (VIN) plates. On January 27, 2016, DMC in Texas announced that it planned to build about 300–325 replica 1982 DMC-12 cars, each projected to cost just under US$100,000.
  • 7.0K
  • 01 Dec 2022
Topic Review
Shenyang J-31
The Shenyang J-31 (or "FC-31 fifth Generation Multi-Purpose light Fighter") also known as the "Gyrfalcon" (鹘鹰), or "Falcon Hawk" by some military enthusiasts, is a twin-engine, mid-size fifth-generation jet fighter currently under development by Shenyang Aircraft Corporation. The fighter has also been referred to as the "F-60" or "J-21 Snowy Owl" (雪鸮) in some media reports. Its official name is Shenyang FC-31; J-xx nomenclatures in the Chinese military are reserved to programs launched and financed by the army, while this plane was developed by a state-owned company.
  • 7.0K
  • 10 Nov 2022
Topic Review
Mitsubishi Challenger
The Mitsubishi Challenger is a mid-size SUV produced by the Japanese manufacturer Mitsubishi Motors since 1996, spanning over three generations. Since 2015, for the third generation model, Mitsubishi has no longer used the Challenger name, but using the Pajero Sport/Montero Sport/Shogun Sport name instead.
  • 6.7K
  • 10 Oct 2022
Topic Review
Slope Stability Analysis
Slope stability analysis is performed to assess the safe design of a human-made or natural slopes (e.g. embankments, road cuts, open-pit mining, excavations, landfills etc.) and the equilibrium conditions. Slope stability is the resistance of inclined surface to failure by sliding or collapsing. The main objectives of slope stability analysis are finding endangered areas, investigation of potential failure mechanisms, determination of the slope sensitivity to different triggering mechanisms, designing of optimal slopes with regard to safety, reliability and economics, designing possible remedial measures, e.g. barriers and stabilization. Successful design of the slope requires geological information and site characteristics, e.g. properties of soil/rock mass, slope geometry, groundwater conditions, alternation of materials by faulting, joint or discontinuity systems, movements and tension in joints, earthquake activity etc. The presence of water has a detrimental effect on slope stability. Water pressure acting in the pore spaces, fractures or other discontinuities in the materials that make up the pit slope will reduce the strength of those materials. Choice of correct analysis technique depends on both site conditions and the potential mode of failure, with careful consideration being given to the varying strengths, weaknesses and limitations inherent in each methodology. Before the computer age stability analysis was performed graphically or by using a hand-held calculator. Today engineers have a lot of possibilities to use analysis software, ranges from simple limit equilibrium techniques through to computational limit analysis approaches (e.g. Finite element limit analysis, Discontinuity layout optimization) to complex and sophisticated numerical solutions (finite-/distinct-element codes). The engineer must fully understand limitations of each technique. For example, limit equilibrium is most commonly used and simple solution method, but it can become inadequate if the slope fails by complex mechanisms (e.g. internal deformation and brittle fracture, progressive creep, liquefaction of weaker soil layers, etc.). In these cases more sophisticated numerical modelling techniques should be utilised. Also, even for very simple slopes, the results obtained with typical limit equilibrium methods currently in use (Bishop, Spencer, etc.) may differ considerably. In addition, the use of the risk assessment concept is increasing today. Risk assessment is concerned with both the consequence of slope failure and the probability of failure (both require an understanding of the failure mechanism). Within the last decade (2003) Slope Stability Radar has been developed to remotely scan a rock slope to monitor the spatial deformation of the face. Small movements of a rough wall can be detected with sub-millimeter accuracy by using interferometry techniques.
  • 6.5K
  • 19 Oct 2022
Topic Review
SSC Aero
The SSC Ultimate Aero is a mid-engined sports car that was produced by SSC North America (formerly known as Shelby SuperCars) from 2004 until 2013. The SSC Ultimate Aero held the world production car speed record title, according to the Guinness World Records, from 2007 (when it was officially timed at 410 km/h) until the introduction of the Bugatti Veyron Super Sport in 2010. In April 2013, the Guinness World Records temporarily disqualified the Veyron's record time for a period of five days due to concerns about electronic speed limiting changing the function of the car, but after investigation reinstated the Veyron as the record holder. The SSC Ultimate Aero was not sold with electronic driver aids such as an anti-lock braking system or traction control system, as according to Jerod Shelby (no relations to Carroll Shelby), "Early design philosophy on the car was to make it a driver's car. I wanted a car that you not only throttled with your right foot but at times you could steer with your right foot and a sensor."
  • 6.4K
  • 04 Nov 2022
Topic Review
Straight-Three Engine
A straight-three engine, also known as an inline-triple, or inline-three (abbreviated I3 or L3), is a reciprocating piston internal combustion engine with three cylinders arranged in a straight line or plane, side by side.
  • 6.1K
  • 31 Oct 2022
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