Convection describes the transfer of thermal energy in liquids and gases. The most used method of transferring thermal energy is to heat a substance and then in turn allow the substance to move, therefore carrying the thermal energy to a new location. This is called convection. Convection is used in our everyday lives without us even realizing; steam from a tea kettle, hot exhaust fumes from cars Justise Winslow Heat Jersey , and even smoke from fires all carry thermal energy from one place and disperse it to another. As stated before, this process relies on two characteristics of liquids and gases. One is that they must flow, carrying thermal energy with them Josh McRoberts Heat Jersey , and the other is that warmed liquids and gasses must rise in their cooler surroundings.
Since warm air rises, it is able to transfer thermal energy from one energy source to another. Convection is known as the process of transferring thermal energy by the movement of warm liquids and gasses to cooler surroundings. A perfect example to better understand convection is to think of a radiator in a closed room. With the radiator acting as the energy source, the air near the radiator is warmed and soon rises James Johnson Heat Jersey , as it moves upward, the air interacts with outside things such as the walls and the furniture. Its molecules collide with these things and with each collision; the thermal energy is transferred from the warmer air to the cooler surroundings. In no time, the air will cool Hassan Whiteside Heat Jersey , sink, and then will be drawn back to the radiator. This process repeats over and over until the radiator is turned off.
Conduction describes the transferring process of energy through solid substances. There is no specific motion in which a material’s molecules is carried away from their original location, but you could probably better understand it using this example: when a pan is being heated on the stove it is only touching the bottom of the pan Goran Dragic Heat Jersey , however, if the pan handle is metal, it quickly becomes too hot to touch. This occurs simply because of conduction.
The effects of the many factors of conduction can be combined into one single equation called the thermal conduction equation. This equation can be used to determine the amount of thermal energy conducted through a material. The thermal conduction equation is:
Thermal energy conducted= (Cross-sectional area) X X (Temperature difference)
The final way thermal energy can be transferred is through radiation and absorption. Radiation-absorption is the process by which thermal energy is transferred through empty space and by electromagnetic waves. A thermal energy source Glen Rice Heat Jersey , such as the sun, converts thermal energy into electromagnetic waves. These waves soon travel to an energy receiver, which convert the electromagnetic wave energy back into thermal energy. The energy source is said to “radiate” the energy and the energy receiver is said to “absorb” it. A perfect example of how this happens is one about a bike seat and a hot sunny day. You leave your bike parked outside for a while in the blazing sun and you come back to ride it home and cannot sit on the seat because of how hot it is. This example shows that your bike seat gained thermal energy from the sun. Radiation-absorption is one of the ways in which objects exchange thermal energy with their surroundings. All objects radiate and absorb thermal energy. If they radiate more energy than they can absorb Gerald Green Heat Jersey , the cooler the object becomes.
In conclusion, thermal energy can be transferred from one location to another by three different processes: convection, conduction Dwyane Wade Heat Jersey , and radiation-absorption.
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BEIJING， March 13 (Xinhua) -- Chinese delivery giant SF Holding on Monday announced that its net profit in 2016 rose 112.5 percent as strong e-commerce drove demand for express deliveries.
In its first annual report released after it went public late last month， SF Holding said its net income reached 4.18 billion yuan (605.4 million U.S. dollars) last year.
In 2016 its revenues rose 19.5 percent to 57.5 billion yuan.
With an 8.25 percent market share， SF Holding generated 14.46 percent of all the revenues in the industry， according to the State Post Bureau of China.
Shares in SF Holding closed the morning session 3.05 percent lower on Monday at 60.99 yuan. The shares earlier surged 46 percent to 73.48 yuan in the four trading days following the listing.
SF Express went public on Feb. 24 on the Shenzhen Stock Exchange through a reverse merger with listed company Dingtai， which announced a name change to SF Holding the same day.
SF Express， founded in 1993 in Guangdong Province， is one of the largest private express logistics firms in China.
China's courier services have grown steadily along with e-commerce development.
The total number of packages delivered increased 51.4 percent year on year in 2016 to more than 31 billion. Total industry revenue hit nearly 400 billion yuan， marking year-on-year growth of 43.5 percent， according to the State Post Bureau of China.
All of China's top five courier services -- STO Express， YTO Express， ZTO Express， Shanghai Yunda Express and SF Express -- are now listed on stock markets.
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