Cycle is a Chinese word, pronounced zh ō u q ī, which comes from Jingzhai Ancient and Modern 黈.If a group of events or phenomena recur in the same order, the time or space interval to complete this group of events or phenomena is called cycle.
[period; cycle] In the process of movement and change of things, some features appear repeatedly for many times, and the time passed by two consecutive occurrences is called "cycle".
Period of pendulum[1]。
Citation explanation
1. In the process of movement, change and development of things, some characteristics appear repeatedly for many times, and the time passed by two consecutive appearances is called cycle[2]。
elementLi ZhiVolume I of "Worship to the Zhai Ancient and Modern": "Things that match yin and yang, and the old and young must be equal. For a policy of doing something, there are six in two hundred and ten, and the old yang is the same; for a policy of kun, there are four in one hundred and forty, and the old yin is the same. If the old yin and the old yang are equal, then the cycle is the same."
2. Repeat the time when the object moves back and forth or the physical quantity changes repeatedly[2]。
AC power completed oncePeriodic changeThe time required is called the period of alternating current.
3. Anniversary.
clearZeng Guofan《Reply to the letter of Chen Huchen》: "The number of vassals moved to Jidian has reached the cycle. The land is barren and the people are poor, and there are no facilities.[1]”
4. Tibetan calendar.
The year, month and day of Zhu Yao, whether calculated by solar day, lunar day or palace day, have their parallelism.From the first year, month and day, after several rotations, the parallelism will return to the whole number without surplus and deficiency. The value of this time is called period (that is, the time required for a celestial body to return to a relative position again is the stellar period of the celestial body).
The periodic table of elements is divided into 7 periods.The first cycle (only containing two elements) is called extra short cycle;The second and third cycles (each containing 8 elements) are called short cycles;The fourth and fifth cycles (each containing 18 elements) are called long cycles;The 6th and 7th cycles (including 32 elements) and the 7th cycle (not yet found) are called extra long cycles.The first, second and third cycles are also called short cycles, and the fourth, fifth, sixth and seventh cycles are called long cycles[3]。
6. The concept of cycle of historians is basically an empirical concept, which is far from the concept of theology and philosophy.In the most general sense of historical research, cycle refers to the cycle of a certain historical phenomenon and level movement.
Mathematical cycle
Announce
edit
Mathematical cycle
The time required to complete a vibration is called the vibration period.
If f (x) is a periodic function, the minimum positive number l that makes f (x+l)=f (x) true for any x in the definition domain is called the (basic) period of f (x).
In the computer, the time required to complete a cycle;Or the time required to access the memory once, also called cycle[4]。The essence of periodic function: twoindependent variableWhen the difference of the whole value is equal to the multiple of the periodindependent variableValue integralfunction valueequal.For example, if f (x+6)=f (x-2), the function period is T=8.
oneperiodic table of ele mentsA classification of elements in.A period is a horizontal row of a series of elements with the same number of electronic layers arranged in the order of increasing atomic number.The metallicity of elements in the same period gradually weakens from left to right,NonmetallicGradually increase.
2. It refers to having the same number of electronic layers andAtomic numberA series of elements arranged in ascending order.There are seven horizontal rows in the periodic table, that is, seven cycles.The first cycle (only containing two elements) is called extra short cycle;The second and third cycles (each containing 8 elements) are called short cycles;The fourth and fifth cycles (each containing 18 elements) are called long cycles;The 6th and 7th cycles (including 32 elements) and the 7th cycle (not yet found) are called extra long cycles.The first, second and third cycles are also called short cycles, and the fourth, fifth, sixth and seventh cycles are called long cycles[3]。
Physical cycle
Announce
edit
oneUniform circular motionIt is a kind of periodic movement. Periodicity refers to that the moving object repeatedly returns to the original position after a certain time, and the instantaneous speed repeatedly returns to the original size and direction.The time it takes for an object to move in a uniform circular motion for one cycle is called period.
Period is also a physical quantity that describes the speed of uniform circular motion. A long period indicates the slow motion of an object, while a short period indicates the fast motion of an object.
2. When the object moves back and forth or the physical quantity changes repeatedly, repeat the time experienced.Object or physical quantity (such asAlternating current, voltage, etc.).In various periodic movements or periodic changes, the object or physical quantity changes from any state, and always returns to the starting state after a period or an integral multiple time of a period.
threealternating currentThe time required to complete a complete change is called the cycle, which is often represented by T.The unit of cycle is second (s), and it is also commonly used as the unit of millisecond (ms) or microsecond (μ s).
The spontaneous or passive activity of the object itself, from the beginning to the end, is called a cycle.The biological cycle is like the movement of celestial bodies. One cycle of the earth around the sun is one year.The cell division of an organism is a cycle, which starts with the cell ready to divide and goes through the prophase, metaphase, anaphase, and anaphase, and finally returns to the interphase.
economic cycle
Announce
edit
Economic cycle is also called "business cycle" and "business cycle".In the UK, it is usually called "trade cycle";In Japan, it is often called "boom cycle".The economic cycle refers to the cyclical fluctuation of the national economy, which is characterized by one fall, expansion and contraction.[5]In the past, it was divided into four stages: prosperity, recession, depression and recovery, generally called recession, bottom, expansion and peak.
