M2-R4 Innovation - Vrindawan Computer Institute

M2-R4 Innovation

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Wikipedia

M² (album), a 2001 album by jazz musician Marcus Miller
m² (artist), an ambient project of Mathis Mootz
M2 (TV channel), a Hungarian TV channel
M2 (Ukraine), a Ukrainian music television channel
M.2, a specification for internally mounted expansion cards
Apple M2, a central processing unit in the Apple M series
Socket M2, a CPU socket
Memory Stick Micro, a removable flash memory card format
Fast Universal Digital Computer M-2, an early Russian digital computer (1957)
Opera Mail, formerly known as M2
Modula-2, a computer programming language
Macaulay2, a free computer algebra system
M2 (game developer)
M2 (missile), a French submarine-launched ballistic missile
M2 Bradley, an armored fighting vehicle
M2 half-track car
M2 light tank
M2 medium tank
HMS Havelock (1915) (M2), a WWI British Royal Navy monitor
HMS M2, a 1919 submarine
HSwMS M2, a Swedish Navy mine sweeper
HSwMS Älvsborg (M02), a Swedish Royal Navy mine layer
Miles M.2 Hawk, a 1930s British two-seat light monoplane
M2 High Speed Tractor, M2 High Speed Tractor aircraft tug
M2 Ball, ammunition
M2 Browning, a heavy machine gun in use since the 1920s
M2 carbine, a select-fire carbine
M2 flamethrower
M2 Hyde, submachine gun
M2 mine, a World War II land mine
M2 mortar, a 60 mm infantry mortar
M2 tripod, a weapon mount
Mauser M2, semi-automatic handgun
M2 Aiming Circle, an optical survey device to measure deflection angles and elevation off a predefined azimuth
M2 compass (Brunton compass), used for mortars and field artillery; uses 6400 mils as opposed to 360 degrees
M2 howitzer, the WW2 designation for the M101 howitzer
M2/M4 Selectable Lightweight Attack Munition (SLAM), a land mine
Anti-Aircraft Target Rocket M2, a World War II training rocket
M2 (New York City bus), a New York City Bus route in Manhattan
Route M-2 (MTA Maryland), a bus route in Baltimore, Maryland and its suburbs
M2 (Copenhagen), a line of the Copenhagen Metro, colored yellow on the map
M2 (Istanbul Metro), a metro line in Turkey
M2 (Lausanne), part of the Lausanne Metro in Switzerland
Paris Métro Line 2, part of the Paris Metro in France
Bucharest Metro Line M2, part of the Bucharest Metro, Romania
Line 2 (Budapest Metro), the second line of Budapest Metro, Hungary
Line M2 (Warsaw Metro), the second line of Warsaw Metro, Poland
Line M2 – Milan Subway (Metro politana di Milano)

List of M2 roads
M2 (Brisbane), Australia
M2 (Johannesburg), a Metropolitan Route in Johannesburg, South Africa
M2 (Pretoria), a Metropolitan Route in Pretoria, South Africa
M2 (Sydney), Australia
M2 motorway (Great Britain)

M2 (railcar), a Metro-North Railroad railcar
BMW M2, a variant of the BMW 2 Series
Freight liner M2, a cube truck and chassis variants

M2 protein, an ion channel in the cell membrane of the influenza A virus
ATC code M02, Topical products for joint and muscular pain, a subgroup of the Anatomical Therapeutic Chemical Classification System
British NVC community M2, a mire biological community in the United Kingdom
Messier 2, a globular cluster in the constellation Aquarius
Muscarinic acetylcholine receptor M₂, a muscarinic receptor for acetylcholine found mainly in the heart
M2 or M₂, the principal lunar semi-diurnal constituent of tides on Earth
M2, a form of high speed steel in the tungsten-molybdenum series
M2 macrophage, a phenotype of macro phage
M2 (economics), a measure of the money supply

M2 (Mazda), a marketing approach by Mazda
M2 Group, an Australian seller of telecommunications services, power, gas, and insurance products
M-2 visa, a type of United States visa for the dependents of an individual with an M-1 visa
Leica M2, a 35 mm rangefinder camera introduced in 1957
Panasonic M2, a video game console design
m² or square metre, a unit of area
M2, one of the ISO metric screw thread sizes

In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux between the warmer surface and colder surface of a barrier under steady-state conditions.

The R-value is the building industry term for thermal resistance “per unit area.” It is sometimes denoted RSI-value if the SI units are used. An R-value can be given for a material (e.g. for polyethylene foam), or for an assembly of materials (e.g. a wall or a window). In the case of materials, it is often expressed in terms of R-value per metre. R-values are additive for layers of materials, and the higher the R-value the better the performance.

The U-factor or U-value is the overall heat transfer coefficient and can be found by taking the inverse of the R-value. It is a property that describes how well building elements conduct heat per unit area across a temperature gradient. The elements are commonly assemblies of many layers of materials, such as those that make up the building envelope. It is expressed in watts per square metre kelvin: W/(m²⋅K). The higher the U-value, the lower the ability of the building envelope to resist heat transfer. A low U-value, or conversely a high R-Value usually indicates high levels of insulation. They are useful as it is a way of predicting the composite behaviour of an entire building element rather than relying on the properties of individual materials.

This relates to the technical/constructional value.

R_{\text{val}}={\frac {\Delta T}{\phi _{q}}}

where:

$R_{\text{val}}$ (K⋅m²/W) is the R-value,
$\Delta T$ (K) is the temperature difference between the warmer surface and colder surface of a barrier,
$\phi _{q}$ (W/m²) is the heat flux through the barrier.

The R-value per unit of a barrier’s exposed surface area measures the absolute thermal resistance of the barrier.

{\frac {R_{\text{val}}}{A}}=R

where:

$R_{\text{val}}$ is the R-value (m²⋅K⋅W⁻¹)
$A$ is the barrier’s exposed surface area (m²)
$R$ is the absolute thermal resistance (K⋅W⁻¹)

Absolute thermal resistance, $R$ , quantifies the temperature difference per unit of heat flow rate needed to sustain one unit of heat flow rate. Confusion sometimes arises because some publications use the term thermal resistance for the temperature difference per unit of heat flux, but other publications use the term thermal resistance for the temperature difference per unit of heat flow rate. Further confusion arises because some publications use the character R to denote the temperature difference per unit of heat flux, but other publications use the character R to denote the temperature difference per unit of heat flow rate. This article uses the term absolute thermal resistance for the temperature difference per unit of heat flow rate and uses the term R-value for the temperature difference per unit of heat flux.

In any event, the greater the R-value, the greater the resistance, and so the better the thermal insulating properties of the barrier. R-values are used in describing the effectiveness of insulating material and in analysis of heat flow across assemblies (such as walls, roofs, and windows) under steady-state conditions. Heat flow through a barrier is driven by temperature difference between two sides of the barrier, and the R-value quantifies how effectively the object resists this drive: The temperature difference divided by the R-value and then multiplied by the exposed surface area of the barrier gives the total rate of heat flow through the barrier, as measured in watts or in BTUs per hour.

\phi ={\frac {\Delta T\cdot A}{R_{\text{val}}}}

where:

$R_{\text{val}}$ is the R-value (K⋅m²/W),
$\Delta T$ is the temperature difference (K) between the warmer surface and colder s urface of the barrier,
$A$ is the exposed surface area (m²) of the barrier,
$\phi$ is the heat flow rate (W) through the barrier.

As long as the materials involved are dense solids in direct mutual contact, R-values are additive; for example, the total R-value of a barrier composed of several layers of material is the sum of the R-values of the individual layers.

For example, in winter it might be 2 °C outside and 20 °C inside, making a temperature difference of 18 °C or 18 K. If the material has an R-value of 4, it will lose 0.25 W/(°C⋅m²). With an area of 100 m², the heat energy being lost is 0.25 W/(K⋅m²) × 18 °C × 100 m² = 450 W. There will be other losses through the floor, windows, ventilation slots, etc. But for that material alone, 450 W is going out, and can be replaced with a 450 W heater inside, to maintain the inside temperature.

Note that the R-value is the building industry term for what is in other contexts called “thermal resistance” “for a unit area. It is sometimes denoted RSI-value if the SI (metric) units are used.

An R-value can be given for a material (e.g. for polyethylene foam), or for an assembly of materials (e.g. a wall or a window). In the case of materials, it is often expressed in terms of R-value per unit length (e.g. per inch of thickness). The latter can be misleading in the case of low-density building thermal insulations, for which R-values are not additive: their R-value per inch is not constant as the material gets thicker, but rather usually decreases.

The units of an R-value (see below) are usually not explicitly stated, and so it is important to decide from context which units are being used: an R-value expressed in I-P (inch-pound) units is about 5.68 times larger than when expressed in SI units, so that, for example, a window that is R-2 in I-P units has an RSI of 0.35 (since 2/5.68 = 0.35). For R-values there is no difference between US customary units and imperial units. As far as how R-values are reported, all of the following mean the same thing: “this is an R-2 window”; “this is an R2 window”; “this window has an R-value of 2”; “this is a window with R = 2” (and similarly with RSI-values, which also include the possibility “this window provides RSI 0.35 of resistance to heat flow”).