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1. Because the energy levels in the nucleus are discrete, the decay of the nucleus is also fixed. What is the same nuclide decaying into is fixed, and some nuclides decays at the same time α Decay and β The ratio of the two decays is also fixed; Some nuclides can only undergo one kind of decay, but these two kinds of decay are accompanied γ Decay. In a word, decay is an inherent property of the nucleus, which can't be regulated or restricted artificially. If you want to know the decay process of each kind of nuclide, please refer to the "decay map of common radionuclides" edited by Liu Yunzuo, Atomic Energy Press

2.

According to modern financial theory, the additional yield of securities investment can be regarded as the sum of two parts. The first part, which has nothing to do with the whole market, is called alpha; The second part is the average rate of return of the whole market multiplied by a beta coefficient. Beta can be called the systemic risk of this portfolio

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stock returns are stock dividends and gains obtained by ownership of shares that exceed the actual purchase price of shares. Investors are most concerned about how much profit they can get when they buy stocks. Specifically, it is the appreciation of dividend and stock market price. There are three kinds of Dividend: cash dividend, share dividend and property dividend

generally, most companies pay cash dividends, and those who don't pay cash dividends are mainly those companies that are growing rapidly, which are for the expansion of the company. More funds need to be held up to meet further needs, which is often accepted by investors. Because dividend is the nominal return of the stock, and the stock price is always changing, the stock holders are more concerned about the expected return brought by the change of the stock price than the dividend

the main indicators to measure the level of return on stock investment are dividend yield, return on holding period and return on holding period after stock split

Dividend yield, also known as yield rate, refers to the ratio of dividend or dividend paid in cash by a joint stock company to the stock market price. Its calculation formula is as follows: the yield can be used to calculate the dividend yield obtained, and can also be used to predict the possible dividend yield in the future

The yield of holding period refers to the ratio of the sum of dividend income and bid ask spread to the purchase price of the stock. The calculation formula is as follows:

the stock has no maturity date, and the time for investors to hold the stock is as short as several days and as long as several years. The yield of holding period reflects the proportion of all dividend income and capital gains of investors in the investment principal in a certain holding period. The yield of holding period is the most concerned index of investors, but if we want to compare it with the yield of bonds, bank interest rates and other financial assets, we should pay attention to the comparability of time, that is, we should convert the yield of holding period into annual rate

The recovery rate of holding period is the ratio of the sum of cash dividend income and the selling price of the stock to the buying price of the stock. This indicator mainly reflects the situation of investment recovery. If the stock price falls or the operation is improper after the investor buys the stock, the selling price of the stock may be lower than the buying price, or even the holding period yield may be negative. At this time, the holding period yield can be used as a supplementary indicator of the holding period yield to calculate the return ratio of the investment principal. The calculation formula is as follows:

4. The return rate of holding period after stock split

after investors buy stocks, the market price of stocks and the number of shares held by investors will change when the stock company issues stock dividends or splits stocks (i.e. stock split). Therefore, it is necessary to adjust the stock price and the number of shares after the split to calculate the holding period yield after the split. The calculation formula is as follows: (closing price - opening price) / opening price the calculation formula of stock return rate is stock return rate = income amount / original investment amount, where: income amount = investment amount recovered + all dividends - (original investment amount + all commission + tax)

3.

1. Look at the title bar to understand the part: look at the title bar to understand the name, material and proportion of the part, so as to roughly understand the function of the part, and judge which kind of part the part belongs to from the name. Judging the rough machining method of the part from the material. Judge the actual size of the part from the proportion, so as to have a preliminary understanding of the part

2. Analyze and study the view, imagine the structure and shape: look at the view, analyze the configuration of each view of the part and the relationship between the views, the expression method and the content of the expression, use the combination of drawing reading method, shape analysis method and line surface analysis method to understand the structure of each part of the part, and imagine the shape, relative position and function of each part of the part

Analyze all dimensions and make clear the dimension requirements: comprehensively analyze the view and shape, analyze the dimension datum of the part in the three directions of length, width and height, then start from the datum, take the structural shape analysis as the clue, understand the setting and positioning dimensions of each shape, and make clear the role of each dimension. Graphics and dimensions express the shape and size of the part Size and shape structure are combined to analyze

Analysis of technical requirements and comprehensive understanding of the whole drawing: when reading the drawing, the technical requirements such as surface roughness, dimensional tolerance and geometric tolerance should be clarified. Understand the meaning of the code. If necessary, contact the parts related to the part for analysis

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precautions:

1. Carefully analyze the drawings to determine a reasonable process route

2. The size of the tool should be selected, and the measured actual size should be filled in the tool card

3. Determine the reasonable cutting parameters. It mainly includes spindle speed, back feed, feed speed, etc

There should be enough space for automatic tool change to avoid collision with workpiece or fixture. It is recommended to set the tool change position at the origin of the machine tool

In order to check and debug the program, the processing contents of each step can be arranged in different subprograms, and the main program mainly completes tool change and subroutine call. This procere is simple and clear

Check and trial run the programmed program, and pay attention to whether there is interference among the tool, fixture or workpiece. When checking m, s and t functions, it can be carried out in the z-axis locking state

reference source: Network NC milling machine

reference source: network drawing

4. Programming is the crystallization of experience, is many years of experience
drawing under normal circumstances is divided into one perspective and three perspectives
coordinates in the machining center there are three: absolute coordinates, relative coordinates, mechanical coordinates, and there is a resial coordinates in the processing mode
to say that fast method, no, this is experience, do more, edit more, write more, think more
an excellent program collection: first class operation experience, first-class adjustment level, first-class process arrangement, first-class tool selection and first-class parameter feeding. So we can only study hard, starting from the most basic

5. Oh, if you can't understand the drawing of the machining center, you can explain it. The manual you just entered can explain it

8.

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