Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
Transmission (Mechanics)
A transmission is a machine in a power transmission system, which provides controlled application of power. Often the term 5-speed transmission refers simply to the gearbox, that uses gears and gear trains to provide speed and torque block conversions from a rotating power source to another device. The term transmission properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differential, and final drive shafts. In the United States the term is sometimes used in casual speech to refer more specifically to the gearbox alone, and detailed usage differs. The most common use is in motor vehicles, where the transmission adapts the output of the internal combustion engine to the drive wheels. Such engines need to operate at a relatively high rotational speed, which is inappropriate for starting, stopping, and slower travel. The transmission reduces the higher engine speed to the slower wheel speed, increasing torque in the process. Transmissions are also used on pedal bicycles, fixed machines, and where different rotational speeds and torques are adapted. Often, a transmission has multiple gear ratios (or simply "gears") with the ability to switch between them as the speed varies. This switching may be done manually (by the operator) or automatically (by a control unit). Directional (forward and reverse) control may also be provided. Single-ratio transmissions also exist, which simply change the speed and torque (and sometimes direction) of motor output. In motor vehicles, the transmission generally is connected to the engine crankshaft via a flywheel or clutch or fluid coupling, partly because internal combustion engines cannot run below a particular speed. The output of the transmission is transmitted via the driveshaft to one or more differentials, which drive the wheels. While a differential may also provide gear reduction, its primary purpose is to permit the wheels at either end of an axle to rotate at different speeds (essential to avoid wheel slippage on turns) as it changes the direction of rotation. Conventional gear/belt transmissions are not the only mechanism for speed/torque adaptation. Alternative mechanisms include torque converters and power transformation (e.g. diesel-electric transmission and hydraulic drive system). Hybrid configurations also exist. Automatic transmissions use a valve body to shift gears using fluid pressures in response to engine RPM, speed, and throttle input.
  • 2.3K
  • 01 Nov 2022
Topic Review
Gaming Computer
A gaming computer, also known as a gaming PC, is a specialized personal computer designed for playing video games. Gaming PCs typically differ from mainstream personal computers by using high-performance video cards and high core-count central processing units with raw performance. Gaming PCs are also used for other demanding tasks such as video editing. Many gamers and computer enthusiasts choose to overclock their CPU(s) and GPU(s) in order to gain extra performance. The added power draw needed to overclock either processing unit often requires additional cooling, using upgraded air cooling or water cooling.
  • 7.5K
  • 01 Nov 2022
Topic Review
List of ASTM International Standards
This is a list of ASTM International standards. Standard designations usually consist of a letter prefix and a sequentially assigned number. This may optionally be followed by a dash and the last two digits of the year in which the standard was adopted. Prefix letters correspond to the following subjects: This list may include either current or withdrawn standards. A withdrawn standard has been discontinued by its sponsoring committee. A standard may be withdrawn with or without replacement.
  • 4.2K
  • 01 Nov 2022
Topic Review
Ozone Depletion by Rocket Launches
Rocket launches used for space exploration continue to gain popularity as the human population grows and technology advances toward the future. Large increases in rocket launch demand could come about for a variety of reasons, including national decisions regarding security, space exploration, significant reductions in launch costs, or the emergence of new markets such as space tourism, manufacturing, or solar power. Rocket launches can affect the natural environment, most specifically the composition of the atmosphere as they travel through it. A major environmental problem faced today is the depletion of the ozone layer in the atmosphere by rockets and other molecular species such as chlorofluorocarbons. Up to forty percent of the total ozone present in the wake of a rocket is destroyed from rocket plumes. Ozone concentrations are calculated using ultraviolet and visible light radiometers attached to rockets. Calculations analyzed from these radiometers are where scientists first noticed the depletion of ozone caused by rockets.
  • 1.5K
  • 01 Nov 2022
Topic Review
Mast Aft Rig
A mast aft rig, alternately referred to as aft-mast rig, is a sailboat sail-plan that uses a single mast set in the aft half of the hull. The mast supports fore-sails that may consist of a single jib multiple staysails, or a crab claw sail. The mainsail is either small or completely absent. Mast aft rigs are uncommon, but are found on a few custom, and production sailboats.
  • 486
  • 01 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.
  • 11.5K
  • 01 Nov 2022
Topic Review
High Dynamic Range (Display and Formats)
High Dynamic Range (HDR) is a video and image technology that improves the way light is represented. It overcomes the limits of the standard format that is named Standard Dynamic Range (SDR). HDR offers the possibility to represent substantially brighter highlights, darker shadows, more details in both sides and more colorful colors than what was previously possible. HDR do not increase display's capabilities, rather it allows to make better use of displays that have high brightness, contrast and colors capabilities. Not all HDR displays have the same capabilities and HDR contents will thus look different depending the display used. HDR emerged first for videos in 2014. HDR10, HDR10+, Dolby Vision and HLG are common HDR formats. Some still pictures formats do also support HDR.
  • 5.6K
  • 01 Nov 2022
Topic Review
Ghost Gun
A ghost gun is a term for a (typically) homemade firearm that lacks commercial serial numbers. The term is used mostly in the United States by gun control advocates, gun rights advocates, law enforcement, and some in the firearm industry. Because home-manufacture of firearms for personal use is not considered to fall under the federal government’s authority to regulate interstate (as opposed to intrastate) commerce, individuals making their own firearms are not subject to federal or state commercial background check regulations. Persons otherwise prohibited from owning firearms are still legally barred from the manufacture, transfer, or possession of firearms or ammunition, regardless of the method of manufacture or acquisition.
  • 343
  • 01 Nov 2022
Topic Review
QuikSCAT
The NASA QuikSCAT (Quick Scatterometer) was an Earth observation satellite carrying the SeaWinds scatterometer. Its primary mission was to measure the surface wind speed and direction over the ice-free global oceans. Observations from QuikSCAT had a wide array of applications, and contributed to climatological studies, weather forecasting, meteorology, oceanographic research, marine safety, commercial fishing, tracking large icebergs, and studies of land and sea ice, among others. This SeaWinds scatterometer is referred to as the QuikSCAT scatterometer to distinguish it from the nearly identical SeaWinds scatterometer flown on the ADEOS-2 satellite.
  • 358
  • 01 Nov 2022
Topic Review
Automobile Dependency
Automobile dependency or car dependency is the concept that some city layouts cause automobiles to be favoured over alternate forms of transportation, such as bicycles, public transit, and walking.
  • 806
  • 01 Nov 2022
  • Page
  • of
  • 678
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
ScholarVision Creations
Feedback