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CN107271493A - A kind of Air Concentration in Water Flow computational methods and system based on normal distribution - Google Patents

A kind of Air Concentration in Water Flow computational methods and system based on normal distribution Download PDF

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Publication number
CN107271493A
CN107271493A CN201710548929.1A CN201710548929A CN107271493A CN 107271493 A CN107271493 A CN 107271493A CN 201710548929 A CN201710548929 A CN 201710548929A CN 107271493 A CN107271493 A CN 107271493A
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data sample
aeration
normal distribution
resistance
water flow
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戴晓兵
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PowerChina Zhongnan Engineering Corp Ltd
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PowerChina Zhongnan Engineering Corp Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10Complex mathematical operations
    • G06F17/15Correlation function computation including computation of convolution operations

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Abstract

The invention discloses a kind of Air Concentration in Water Flow computational methods and system based on normal distribution, aeration concentrater calculating is carried out using the dynamic data sample of aerated flow electrical conductivity, in addition to calculating average aeration concentrater, the aeration concentrater for calculating different frequency can also be sought, aeration concentrater is measured achievement more horn of plenty, more can comprehensively reflect the air mixing corrosion reducing effect of air entraining facilities.

Description

A kind of Air Concentration in Water Flow computational methods and system based on normal distribution
Technical field
It is specifically that one kind measures aeration with conductance instrument the present invention relates to a kind of computational methods of Air Concentration in Water Flow The conductivity data of water flow dynamic, and be converted into dynamic aeration resistance and when aeration resistance meets normal distribution, ask calculation The computational methods and system of Air Concentration in Water Flow.
Background technology
In Hydraulic and Hydro-Power Engineering practice, cavitation erosion easily occurs for high-velocity flow outlet structure escape works concrete surface, leads to Normal solution is that air entraining facilities is set in runner, using the effect forcing high-velocity current aeration of air entraining facilities, to reach Reduce or remit the purpose of cavitation erosion.Air Concentration in Water Flow is to weigh air entraining facilities arrangement and the rational important indicator of structural style.
High-velocity flow aeration is a random process, and aeration concentrater is bigger, and (bubble is more in water body) aeration resistance is bigger, Otherwise smaller, clear water resistance during non-aeration is minimum.Aeration resistance is used as the basic Normal Distribution of stochastic variable or Pearson came III type is distributed.When the aeration resistance and clear water resistance of known current, aeration concentrater can be calculated with Maxell formula.
Maxell proposes the computation model for the whole ball resistivity for calculating two kinds of different resistivity materials, model Assuming that one is to be dispersed with the small ball that several resistivity are k2 materials 2, roundlet in the big ball of k1 materials 1 full of resistivity The distance between ball is much larger than the diameter of small ball, to ensure not producing influence each other.The calculation formula of ball resistivity For:
In formula, K is the resistivity of whole ball;K1 is the resistivity of material 1;K2 is the resistivity of material 2;P is material 2 Percentage of the total volume.
Resistivity calculation formula is applied in aerated flow, material 1 is water, material 2 is bubble, takes the resistivity of air K2=+ ∞, abbreviation formula obtains the percentage by volume of bubble in aerated flow, i.e. aeration concentrater C:
In formula, C is aeration concentrater;R0For the clear water resistance of not bubbles;RcFor the aeration resistance of gassiness current.
Now widely used aeration concentrater measuring instrument is resistance-type entrained air concentration meter, can only measure the average aeration of current Resistance, and must have an aeration sensor (being referred to as clear water measuring point sensor, positioned at the upstream of air entraining facilities) when measuring same The clear water resistance of non-aerated flow is measured in one period.Asked by the ratio measured value of aeration measuring point sensor and clear water measuring point sensor The clear water resistance of each aeration measuring point is calculated, and then calculates the average aeration concentrater of aeration measuring point.
With the development of detecting instrument equipment and computer data acquiring technology, conductance instrument is mixed applied to current In the measurement of gas concentration, and the dynamic measurement of current electrical conductivity is realized, closed because resistance and the electrical conductivity of current are inversely proportional System, therefore the dynamic electric resistor of current can be calculated.Conductance instrument is used for aeration concentrater measurement and is still in starting developing stage, So far without a kind of rational aeration concentrater computational methods, therefore in the urgent need to a kind of dynamic measuring data asks calculation current aeration dense The computational methods of degree.
The content of the invention
The present invention is intended to provide a kind of Air Concentration in Water Flow computational methods and system based on normal distribution, flat except calculating Outside equal aeration concentrater, the aeration concentrater for calculating different frequency can also be sought, aeration concentrater is measured achievement more horn of plenty, more can be comprehensive Ground reflects the air mixing corrosion reducing effect of air entraining facilities.
In order to solve the above technical problems, the technical solution adopted in the present invention is:A kind of current based on normal distribution are mixed Gas density calculating method, comprises the following steps:
1) the conductivity data sample of dynamic acquisition aerated flow;
2) conductivity data sample is converted into resistance data sample, and according to normal distribution " 3 σ rules " to data sample This progress is pre-processed;
3) parameter and graphing of pretreated data sample are calculated;
4) parameter and figure to data sample are analyzed:When coefficient of skew Cs → 0, mode M0 ≈ median Me, generally Rate density curve tends to ± ∞ in two ends, and during using x-axis as the unimodal curve of asymptote, judges that data sample meets normal state point Cloth, into step 5);Otherwise, terminate;
5) the clear water resistance R of aeration measuring point is calculatedi0
6) by given frequency P, the aeration resistance Rcp that frequency is P is calculated;
7) the aeration concentrater Cp that frequency is P is calculated using following formula:
Step 1) in, utilize the conductivity data sample of conductance instrument dynamic acquisition aerated flow.Cost is low, realizes Simply.
Step 1) in, the sample frequency of conductance instrument is 10Hz, and conductivity data sample is no less than at 1024 points.Ensure Measurement accuracy.
Step 3) in, probability density curve is drawn with NORMDIST functions, drawing process is simple, easily realizes.
Step 5) the process that implements be:The clear water electricity of clear water measuring point is calculated with the data sample of clear water measuring point sensor Hinder R0, when the ratio measured value of aeration measuring point sensor and clear water measuring point sensor is ρ i, then the clear water resistance R of aeration measuring pointi0= R0*ρi.The computational methods are simple, and the result of calculation degree of accuracy is high.
Step 6) in, aeration resistance Rcp is calculated with NORMINV functions, calculates simple, easily realizes.
Correspondingly, present invention also offers a kind of Air Concentration in Water Flow computing system based on normal distribution, including:
Acquisition module:Conductivity data sample for dynamic acquisition aerated flow;
Pretreatment module:Conductivity data sample for acquisition module to be gathered is converted to resistance data sample, and according to Data sample is pre-processed according to " the 3 σ rules " of normal distribution;
Graphic plotting module:Parameter and graphing for calculating pretreated data sample;
Analytic unit:Analyzed for parameter and figure to data sample:When coefficient of skew Cs → 0, mode M0 ≈ Median Me, probability density curve tends to ± ∞ in two ends, and during using x-axis as the unimodal curve of asymptote, judges data sample Meet normal distribution;
First computing unit:Following parameter calculating is carried out for the data sample to normal distribution:Calculate aeration measuring point Clear water resistance Ri0With the aeration resistance Rcp that frequency is P;
Second computing unit:For the output according to the first computing unit, the aeration concentrater Cp that frequency is P is calculated:
In the present invention, in order to react sample properties more fully hereinafter, the parameter of the data sample is flat including aeration resistance Average Rc, standard deviation sigma, coefficient variation Cv, coefficient of skew Cs, mode M0, median Me and time graph, probability density are bent Line.
Compared with prior art, the advantageous effect of present invention is that:The present invention is averaged in addition to aeration concentrater except calculating, The aeration concentrater for calculating different frequency can also be sought, aeration concentrater is measured achievement more horn of plenty, more can comprehensively reflect that aeration is set The air mixing corrosion reducing effect applied.
Brief description of the drawings
Fig. 1 is flow chart of the method for the present invention;
Fig. 2 is the time course line of the embodiment of the present invention;
Fig. 3 is the probability density curve of the embodiment of the present invention;
Fig. 4 is the fit curves of the embodiment of the present invention.
Embodiment
As shown in figure 1, the method flow of the present invention is as follows:
Step 1, with the electrical conductivity number of conductance instrument coupled computer data collecting system dynamic acquisition aerated flow According to sample, sample frequency 10Hz, sample data is no less than at 1024 points;
Step 2, conductivity data sample is converted into resistance data sample, and according to normal distribution " 3 σ rules " to sample Notebook data is pre-processed;
Step 3, the parameter and graphing of data sample are calculated, including:Aeration resistance average value Rc, standard deviation are (square Difference) it is σ, coefficient variation (coefficient of dispersion) Cv, the coefficient of skew (deviation factor) Cs, mode M0, median Me and time graph, general Rate density curve etc. (as shown in table 1 and Fig. 2, Fig. 3);
The embodiment data sample parameter table of table 1
Parameter name Numerical value
Aeration resistance average value Rc 1156
Standard deviation sigma 131
Coefficient variation Cv 0.114
Coefficient of skew Cs 0.112
Mode M0 1284
Median Me 1167
Step 4, parameter and figure to data sample carries out comprehensive analysis:The time course line of data sample reflects number According to the rule that changes with time, the general statistical property with stationary random process may determine that the reasonability of data accordingly.By In Cs → 0, M0 ≈ Me, probability density curve tends to ± ∞ in two ends, and the unimodal curve by asymptote of x-axis is (such as Fig. 3 institutes Show), so can judge that data sample meets normal distribution substantially;
Step 5, clear water resistance R is calculated with the data sample of clear water measuring point sensor0=829 Ω;
Step 6, measurement is compared with aeration measuring point sensor and clear water measuring point sensor, obtained ratio measured value ρ i are 0.9891, calculate the clear water resistance Ri0=820 Ω of aeration measuring point;
Step 7, by given frequency P, the aeration resistance Rcp (as shown in Figure 4) that frequency is P is calculated with NORMINV functions;
Step 8, the aeration concentrater Cp that frequency is P is calculated:
Embodiment calculating achievement is as shown in table 2.
The embodiment aeration concentrater calculating achievement table of table 2

Claims (9)

1. a kind of Air Concentration in Water Flow computational methods based on normal distribution, it is characterised in that comprise the following steps:
1) the conductivity data sample of dynamic acquisition aerated flow;
2) conductivity data sample is converted into resistance data sample, and data sample entered according to " the 3 σ rules " of normal distribution Row pretreatment;
3) parameter and graphing of pretreated data sample are calculated;
4) parameter and figure to data sample are analyzed:When coefficient of skew Cs → 0, mode M0 ≈ median Me, probability is close Line of writing music tends to ± ∞ in two ends, and during using x-axis as the unimodal curve of asymptote, judges that data sample meets normal distribution, enter Enter step 5);Otherwise, terminate;
5) the clear water resistance R of aeration measuring point is calculatedi0
6) by given frequency P, the aeration resistance Rcp that frequency is P is calculated;
7) the aeration concentrater Cp that frequency is P is calculated using following formula:
2. the Air Concentration in Water Flow computational methods according to claim 1 based on normal distribution, it is characterised in that step 1) In, utilize the conductivity data sample of conductance instrument dynamic acquisition aerated flow.
3. the Air Concentration in Water Flow computational methods according to claim 2 based on normal distribution, it is characterised in that step 1) In, the sample frequency of conductance instrument is 10Hz, and conductivity data sample is no less than at 1024 points.
4. the Air Concentration in Water Flow computational methods according to claim 1 based on normal distribution, it is characterised in that step 3) In, the parameter of the data sample includes aeration resistance average value Rc, standard deviation sigma, coefficient variation Cv, coefficient of skew Cs, mode M0, median Me and time graph, probability density curve.
5. the Air Concentration in Water Flow computational methods according to claim 1 based on normal distribution, it is characterised in that step 3) In, draw probability density curve with NORMDIST functions.
6. the Air Concentration in Water Flow computational methods according to claim 1 based on normal distribution, it is characterised in that step 5) The process that implements be:The clear water resistance R of clear water measuring point is calculated with the data sample of clear water measuring point sensor0, when aeration is surveyed When the ratio measured value of point sensor and clear water measuring point sensor is ρ i, then the clear water resistance R of aeration measuring pointi0=R0*ρi。
7. the Air Concentration in Water Flow computational methods according to claim 1 based on normal distribution, it is characterised in that step 6) In, calculate aeration resistance Rcp with NORMINV functions.
8. a kind of Air Concentration in Water Flow computing system based on normal distribution, it is characterised in that including:
Acquisition module:Conductivity data sample for dynamic acquisition aerated flow;
Pretreatment module:Conductivity data sample for acquisition module to be gathered is converted to resistance data sample, and according to just " the 3 σ rules " of state distribution is pre-processed to data sample;
Graphic plotting module:Parameter and graphing for calculating pretreated data sample;
Analytic unit:Analyzed for parameter and figure to data sample:When coefficient of skew Cs → 0, mode M0 ≈ middle positions Number Me, probability density curve tends to ± ∞ in two ends, and during using x-axis as the unimodal curve of asymptote, judges that data sample meets Normal distribution;
First computing unit:Following parameter calculating is carried out for the data sample to normal distribution:Calculate the clear water of aeration measuring point Resistance Ri0With the aeration resistance Rcp that frequency is P;
Second computing unit:For the output according to the first computing unit, the aeration concentrater Cp that frequency is P is calculated:
9. the Air Concentration in Water Flow computing system according to claim 8 based on normal distribution, it is characterised in that the number Include aeration resistance average value Rc, standard deviation sigma, coefficient variation Cv, coefficient of skew Cs, mode M0, median according to the parameter of sample Me and time graph, probability density curve.
CN201710548929.1A 2017-07-07 2017-07-07 A kind of Air Concentration in Water Flow computational methods and system based on normal distribution Pending CN107271493A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108875223A (en) * 2018-06-25 2018-11-23 中国电建集团中南勘测设计研究院有限公司 A kind of judgment method of air mixing corrosion reducing facility validity
CN110866043A (en) * 2019-10-12 2020-03-06 上海上湖信息技术有限公司 Data preprocessing method and device, storage medium and terminal
CN111898071A (en) * 2020-07-30 2020-11-06 江西理工大学 Method for calculating in-path velocity of high-pressure submerged water jet

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CN104007142A (en) * 2014-06-04 2014-08-27 浙江省水利河口研究院 Tide head reoxygenation capability testing method for strong tidal bore spreading process
CN105929016A (en) * 2016-04-20 2016-09-07 浙江中烟工业有限责任公司 Value determination method for selenium content of quality control sample of tobacco leaf
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CN1589399A (en) * 2001-11-19 2005-03-02 松下电器产业株式会社 Measurement device for measuring electric signal emitted by biological sample and measurement method
US20070134651A1 (en) * 2002-05-13 2007-06-14 Matsushita Electric Industrial Co., Ltd. Apparatus and method for measuring activity signals of biological samples
CN101324908A (en) * 2008-08-01 2008-12-17 重庆大学 Multi-dimension analogy method of solid-oxide fuel battery
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108875223A (en) * 2018-06-25 2018-11-23 中国电建集团中南勘测设计研究院有限公司 A kind of judgment method of air mixing corrosion reducing facility validity
CN110866043A (en) * 2019-10-12 2020-03-06 上海上湖信息技术有限公司 Data preprocessing method and device, storage medium and terminal
CN111898071A (en) * 2020-07-30 2020-11-06 江西理工大学 Method for calculating in-path velocity of high-pressure submerged water jet
CN111898071B (en) * 2020-07-30 2024-01-30 江西理工大学 Calculation method for high-pressure submerged water jet flow along-distance speed

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