The origin of world civilization is probably, the origin of world civilization in ancient history?

When did the origin of world civilization be, about 5,000 years ago, there was a world civilization.

The origin of world civilization is probably in China and ancient Egypt!

1. The birthplace of the world's civilization is documented by the four ancient civilizations, all of which have something in common, all near rivers, and are generally used to refer to the four regions where human civilization was born at the earliest, such as ancient Babylon, ancient Egypt, ancient China, and ancient India;

2. However, due to the lack of accurate documentary records of ancient civilizations, there is still a debate in the academic circles about the specific birth time of ancient civilizations. There are references to ancient Greece rather than ancient Babylon, as well as Mesopotamia and sub-arts. And a lot of philosophical, scientific, literary, artistic and other knowledge that human beings have today can generally be traced back to these ancient civilizations;

3. Scholars believe that the four major civilizations were all established near the river plateau, because there were fixed water sources that made it easier for agriculture and commerce to develop, and the two river basins, the Nile, the Yellow River, the Yangtze River basin, and the Indus River and the Ganges River basin in the northern hemisphere successively produced the world's four major civilizations;

4. From 7,000 to 4,000 years ago, the ancient civilization entered the Bronze Age from the Neolithic Age, and then entered the Iron Age; The social system was mostly slavery, and state power was born relatively late, and Sumerian in Mesopotamia was the earliest known civilization in the world.

Discharge cooling is another type of convection cooling. Unlike regenerative cooling, the coolant used for exhaust cooling absorbs heat to the thrust chamber and is discharged out of the combustion chamber instead of entering the combustion chamber to participate in combustion. Direct drain coolant reduces the thrust chamber specific impulse, so the coolant flow for drain cooling needs to be minimized while only using drain cooling at the outlet section of the nozzle that is relatively less heated.

There is also radiative cooling, in which the heat flow is transferred from the combustion products to the thrust chamber, and then the heat is radiated by the thrust chamber wall to the surrounding space. Radiative cooling is characterized by simplicity and small structural mass. It is mainly used in the extension section of large nozzles and the thrust chamber of small thrust engines using high-temperature resistant materials.

When cooling in the thrust chamber of the tissue, a relatively low temperature liquid or gas protective layer is established on the surface of the thrust chamber wall to reduce the heat flow to the thrust chamber wall, reduce the wall temperature, and achieve cooling. Internal cooling is mainly divided into three methods: internal cooling (shield cooling), membrane cooling and diaphoretic cooling of head tissues. After the internal cooling measures are adopted in the thrust chamber, the mixing ratio near the wall of the combustion chamber is different from the optimal mixing ratio in the central area (in most cases, the near-wall layer rich in fuel is used) due to the need to reduce the temperature of the protective layer, resulting in the uneven distribution of the mixing ratio along the cross-section of the combustion chamber, so that the combustion efficiency is reduced to a certain extent.

Membrane cooling is similar to shield cooling in that it cools the thrust chamber wall by establishing a uniform and stable coolant film or air film protective layer near the inner wall surface, except that the coolant used to establish the protective layer is not injected by the injector, but is supplied through a special cooling belt. The cooling band is generally arranged in a cross-section of the combustion chamber or the convergence section of the nozzle. There can be several cooling bands along the length of the combustion chamber.

In order to improve the stability of the membrane, the coolant often flows through the gaps or small holes in the cooling belts, and when sweating is used, the thrust chamber wall or part of the inner wall is made of porous material with a pore diameter of tens of microns. Porous materials are usually sintered with metal powders or pressed with metal mesh. In this case, the number of pores per unit area is increased by making the micropores in the material as evenly distributed as possible.

The liquid coolant penetrates into the inner wall, creating a protective film that reduces the density of the heat transferred to the wall. When the flow rate of liquid coolant used for sweat cooling is above a certain threshold, a liquid film is formed near the wall of the thrust chamber. When the coolant flow rate is below the critical flow, the inner wall temperature will be higher than the coolant boiling point at the current pressure, and some or all of the coolant will evaporate, forming an air film.

In addition to the above thermal protection, there are other thermal protection methods such as: ablation cooling, thermal insulation cooling, hot melt cooling and composite protection of chamber walls. 3. Thermal protection scheme of high enthalpy gas generator Based on the above methods and the actual situation, the thermal protection method of high enthalpy gas generator is obtained.

The combustion chamber of a high-enthalpy gas generator differs from that of a liquid rocket engine, eliminating the front thrust chamber part, making its structure simpler and more effective. Then, the thermal protection involved is the thermal protection part of the combustion chamber wall. As the fuel enters the combustion chamber, it quickly decomposes and releases large quantities.

Ancient Chinese civilization originated in 3000 BC.

The focus of the exploration of ancient Chinese civilization is from the period of the "Five Emperors" recorded in literature to the establishment of the Qin Dynasty, that is, from 3000 BC to 221 BC.

The preliminary topics include: the culture and society of the Yellow Emperor, the Yan Emperor and the Yao Shunyu period, the origin of Chinese characters, the changes in the environment during the Xia, Shang and Zhou dynasties, the origin of agriculture and animal husbandry, the development of handicrafts, the origin of cities, the relationship between the origin of war and civilization and the formation of kingship, the origin of religious beliefs, and the comparison of ancient Chinese civilization with other ancient civilizations in the world.

Archaeologists will extract the genes of ancient humans from 5,000 years ago in the main activity area of the legendary Yanhuang Group, and compare them with those of the Xia, Shang and Zhou dynasties, the Qin and Han dynasties, and even modern China to study the formation process of the Chinese nation.

The Origin of the Four Great Civilizations:

1. Two River Basins: The Two River Basins gave birth to ancient Babylon, which was located in the Mesopotamian plain, roughly within the territory of the present-day Republic of Iraq. About 5,000 years ago, the ancient Babylonian kingdom appeared here;

2. Nile River Basin: Ancient Egypt, located in the middle and lower reaches of the Nile River in northeast Africa. The ancient Egyptian civilization was formed around 6,000 years ago, and the pre-dynasty of ancient Egypt began around 5,100 years ago.

3. Ganges River Basin: Ancient India, including present-day India, Pakistan and other countries. The Ganges culture flourished between 1800 and 600 BC during the famous Vedic era in India.

The Vedic era is divided into the Early and Later Vedic periods, the early period is the Rig Vedic period, which is about 1800 to 1000 BC; The later period was between 1000 and 600 BC;

4. The Yellow River and Yangtze River Basin: "Ancient China" is the name of China, that is, the Chinese civilization, which belongs to the great river Wennachaiming. China has been an ancient cultural country since ancient times, and its 5,000-year-old civilization has never had a complete cultural fault.

Backed by the two mother rivers of the Yellow River and the Yangtze River, the Chinese nation has continued to reproduce and develop, and finally gave birth to China's 5,000-year-old broad and profound cultural tradition.

It can be roughly divided into three stages: the foundation period of the three major material prerequisites for the origin of civilization, the generation period of the three major elements of the origin of civilization, and the period of the formation of the overall symbol of civilization.

1. The foundation period of the three major material premises: the revolution in the origin of the agricultural reputation sail industry, the Neolithic revolution, and the pottery revolution.

So far, archaeology and history, from the West to the East, have mostly excluded this stage from the era of the origin of civilization, and at most can be traced back to the origin of bronze, cities, and writing. The new proposition put forward here is to lay the foundation of the three material prerequisites of "agriculture, Neolithic, and pottery" as the first stage of the era of the origin of civilization.

2. The generation period of the three major elements of civilization: the pluralistic occurrence of "bronze, city, and writing".

The elements of civilization are also necessary.