It means the limit value of the number of words.

"Valve (fá) value" is a wrong word, and its correct usage is "threshold (yù) value". Threshold, also called critical value, refers to the lowest or highest value that an effect can produce.

Valve (fá): control, switch, control.

Mechanical term refers to the components used to control liquid or gas in pipelines. It means valve, switch, control. Such as stop valve, pressure reducing valve, safety valve.

Threshold (yù): range, boundary, degree.

Threshold, threshold, extended to the boundary, boundary threshold, vision threshold.

It can be seen that "valve" and "threshold" are two words with different meanings. So is "threshold" a new word? After checking, no. When expressing the meaning of "boundary" and "range", "threshold" should be used instead of "valve". The threshold corresponds to the English threshold value.

In the new editions of "Modern Chinese Dictionary" and "Modern Chinese Standard Dictionary", the word "threshold" is not included; however, it is commonly misused in daily life and even in many scientific research papers. phenomenon.

The limit of a field or a system is called a threshold, and its value is called a threshold. There are thresholds in every science.

1. Mathematics

In mathematics, in the functional relationship y=f(x), the value of the independent variable x must be within the domain of the function, so that the dependent variable y= can have a definite value. The domain of this function is the threshold of x.

2. Chemical system engineering

Thresholds are used to calculate optimization problems in chemical system engineering. It is often unreasonable to make a decision subjectively, and it is often impossible to obtain the optimal value by randomly determining a decision value. Therefore, certain mathematical restrictions must be placed on the value range of the independent variables during calculation, and all points that satisfy these restrictions (thresholds) constitute the feasible domain of the optimization problem.

3. Automatic control system

The minimum input value that can produce a corrective action in the automatic control system.

4. Biological Sciences

The lowest value of the stress tissue response caused by stimulation. The meaning of critical value is that when the biological system is stimulated, although it does not respond to small stimuli, it will react violently when it exceeds a certain limit.

5. Photoshop

Explanation in the graphics computer software photoshop: The "threshold" command converts grayscale or color images into high-contrast black and white images. You can specify a certain color level as a threshold. All pixels lighter than the threshold are converted to white; all pixels darker than the threshold are converted to black. The Threshold command is useful for determining the lightest and darkest areas of an image.

Threshold in PhotoShop? The threshold is the critical value. The threshold in PS is actually a black and white dividing value based on the brightness of the picture. The default value is 50% neutral gray, which is 128, and the brightness is higher than 128 (50% gray) will turn black. You can keep it with the other high contrast in the filter, and then use the threshold for better results.

6. Earthquake Engineering

In earthquake engineering, the duration of strong earthquakes can be defined as the first peak point and the last peak exceeding a certain acceleration threshold (usually 0.05g) The time period between points.