CN100461210C - Nerve network input parameter screening method based on fuzzy logic - Google Patents

Abstract

The invention relates to the field of textiles, it involves neural network input parameters screening method based on the indistinct logic. It includes the following steps: (1) acquiring the necessary data of the neural network modeling; (2) pre-treating the input and output parameters of the neural network; (3) calculating the specific value which can reflect the coincide degree of the changes trend of the experimental data with the expert knowledge; (4)calculating the specific value which can reflect the sensitivity degree of input parameters to output parameters; (5) combining the specific value of coincide degree with the specific value of sensitivity degree to get the specific value which can reflect the intimate relation between the input parameters and output parameters; (6) According to the sequence of the intimate relation, the input parameters of the neural network are screened. The invention can be simpler and quicker to screen the neural network input parameters, particularly applicable to constructing the neural network model of small size samples in the field of textile.

Description

A kind of nerve network input parameter screening method based on fuzzy logic

Technical field

The invention belongs to field of textiles, relate to a kind of nerve network input parameter screening method based on fuzzy logic.

Background technology

Neural network be by a large amount of, also be simultaneously that simple processing unit (being neuron) interconnects and the complex networks system that forms widely.The passage that transmits signal is not only in connection between each neuron, but the more important thing is that a weighting coefficient (being weights) is arranged in the connection between every pair of neuron, and it can strengthen or weaken a last neuronic output to the neuronic stimulation of the next one.Neural network has very strong self-learning capability and adaptive ability, and not resembling the statistical model has strict requirement to data, also can realize effective match to the data that contain noise.Therefore, nerual network technique has application more widely in fields such as system's control, pattern-recognition, medical diagnosis, information retrieval, performance prediction and process optimizations.

But in a lot of fields, the object of application nerual network technique often has only sample seldom, and it is unrealistic to obtain a large amount of samples.Therefore, at this moment just be faced with the less difficulty of sample size.And nerual network technique also has certain requirement to the sample size of modeling.In order to solve the neural net model establishing problem under this type of small sample amount situation, people have carried out many explorations, and wherein a thinking is exactly the scale that reduces neural network by the quantity that reduces input parameter, just nerve network input parameter is screened.Someone screens according to artificial judgement, but this method is too subjective and the shortage universality.Someone utilizes relevant function method to screen, but this method is insensitive to the nonlinear relationship between the input and output, ignores the important input parameter that the nonlinear dependence relation is arranged with output parameter easily.Someone adopts the quadrature least square method to screen, but this method is not suitable for the continuous time series data, and computation process is quite complicated.Someone adopts the pruning method based on susceptibility, but this method belongs to a kind of examination difference method, and what find usually is not globally optimal solution, and calculates also very time-consuming.Someone adopts principal component analysis (PCA), but because this method also is a kind of linear method, therefore can ignore the input parameter that the nonlinear dependence relation is arranged with output parameter; And the major component space do not have physical meaning, is difficult to deep explanation; In addition, major component is the simple transformation of input parameter, does not also consider the situation of output parameter when conversion, and therefore, the major component that comes the front is not necessarily the closest with the output parameter relation.Also do not see at present a kind of explicit physical meaning, calculate simple and efficient nerve network input parameter screening method.

Summary of the invention

The purpose of this invention is to provide a kind of nerve network input parameter screening method, solve technical matters easy, that quickly the input parameter of neural network is screened based on fuzzy logic.This screening technique was both considered from the angle that experimental data concerns each other, investigate the sensitivity of neural network output parameter to its input parameter, consider from the angle of experimental data and expertise mutual relationship again, therefore output parameter is a kind of method of subjective and objective combination with respect to the variation tendency of input parameter and the degree of agreement of expertise in the investigation experimental data.And utilize two kinds of methods determine subjective and objective in conjunction with the time weight coefficient.This screening technique calculates that technology is simple, and physical meaning is clear and definite, can be quickly and easily the input parameter of neural network be screened, and is specially adapted to the less neural net model establishing problem of field of textiles sample size.

The present invention is achieved through the following technical solutions:

A kind of nerve network input parameter screening method based on fuzzy logic is characterized in that this method comprises the steps:

(1) obtain the neural net model establishing desired data: this method is that the relation of non-weaving cloth structural parameters and ultimate strength is set up a neural network model, must obtain following data: fibre length, fibre fineness, porosity, weight uniformity, thickness, weight per unit area, fiber volume density and ultimate strength, wherein, the first seven is the non-weaving cloth structural parameters, the input parameter of neural network just, ultimate strength is the output parameter of neural network;

(2) input and output parameter to neural network carries out pre-service: in order to eliminate the difference of all kinds of parameter yardsticks aspect, input and output parameter all be normalized between-1 and 1;

(3) calculate the character numerical value of reflection experimental data variation tendency and expertise degree of agreement: the degree of agreement character numerical value is to be that output parameter calculates with respect to the variation tendency of input parameter and the degree of agreement of expertise in the experimental data according to experimental data and expertise mutual relationship;

If X _s=(x _S1, x _S2..., x _Sk..., x _Sn) ^TBe the input vector of neural network, Y _s=(y _S1, y _S2..., y _Sj..., y _Sm) ^TOutput vector for neural network; S sample s ∈ of subscript " s " expression 1 ..., i ..., 1 ..., z};

With domain y _jOn average be divided into t interval C _Jp, p ∈ 1 ..., t-1} is according to output parameter y _jInterval C _JpConstruct input parameter x _kCorresponding interval A _Kp

Set up following fuzzy rule:

(a) if certain input parameter x _kIncrease certain output parameter y _jAlso corresponding increase, the pass coefficient value R (x between them so _k, y _j) be+1;

(b) if certain input parameter x _kIncrease certain output parameter y _jCorresponding reducing, the pass coefficient value R (x between them so _k, y _j) be-1;

(c) if certain input parameter x _kReduce certain output parameter y _jCorresponding increase, the pass coefficient value R (x between them so _k, y _j) be-1;

(d) if certain input parameter x _kReduce certain output parameter y _jAlso corresponding reducing, the pass coefficient value R (x between them so _k, y _j) be+1;

Degree of agreement character numerical value V is calculated by formula (1):

$\left\{\begin{array}{c}{V}_k(x_k,y_j)=\frac{1}{t-1}\underset{p=1}{\overset{t-1}{\mathrm{\Σ}}}{v}_p\\ \begin{array}{cc}{x}_{\mathrm{kp}}^{\inf }=\underset{s\∈\{1,...,z\}}{\min }\left\{x_{\mathrm{sk}}\right|y_{\mathrm{sj}}\∈C_{\mathrm{jp}}\}& x_{\mathrm{kp}}^{\sup }=\underset{s\∈\{1,...,z\}}{\max }\left\{x_{\mathrm{sk}}\right|y_{\mathrm{sj}}\∈C_{\mathrm{jp}}\}\end{array}\\ \mathrm{if}{I}_{\mathrm{kp}}=\mathrm{\φ},\left\{\begin{array}{c}{v}_p=\frac{1}{2}\left|R(x_k,y_j)\right|\×[1+R(x_k,y_j)],\mathrm{if}{x}_{\mathrm{kp}+1}^{\inf }\≥x_{\mathrm{kp}}^{\sup }\\ v_p=\frac{1}{2}\left|R(x_k,y_j)\right|\×[1-R(x_k,y_j)],\mathrm{if}{x}_{\mathrm{kp}+1}^{\sup }\≤x_{\mathrm{kp}}^{\inf }\end{array}\right.\\ \mathrm{if}{I}_{\mathrm{kp}}\≠\mathrm{\φ},\left\{\begin{array}{c}{v}_p=\frac{1}{2}\left|R(x_k,y_j)\right|\×[1+R(x_k,y_j)]\×(1-\frac{\left|I_{\mathrm{kp}}\right|}{{|U}_{\mathrm{kp}}|}),\mathrm{if}{x}_{\mathrm{kp}+1}^{\sup }\≥x_{\mathrm{kp}}^{\sup }\\ v_p=\frac{1}{2}\left|R(x_k,y_j)\right|\×[1-R(x_k,y_j)]\×(1-\frac{\left|I_{\mathrm{kp}}\right|}{{|U}_{\mathrm{kp}}|}),\mathrm{if}{x}_{\mathrm{kp}+1}^{\inf }\≤x_{\mathrm{kp}}^{\inf }\end{array}\right.\end{array}\right.$

(1)

In the formula, R (x _k, y _j) be input parameter x _kWith output parameter y _jRelational index, v _pBe interval C _JpThe degree of agreement character numerical value, φ is an empty set,

With Be the interval A of difference _KpLower boundary and coboundary, I _KpAnd U _KpBe respectively interval A _KpAnd A _Kp+1Common factor and union, see Fig. 1, V _kBig more, output parameter y then _jWith respect to input parameter x _kThe variation tendency and the degree of agreement of expertise high more;

(4) calculate the character numerical value of reflection input parameter to the output parameter sensitivity: sensitivity character numerical value S concerns to be that the neural network output parameter calculates the sensitivity of nerve network input parameter each other according to experimental data;

Set up following fuzzy rule:

(e) if the very little variation of input parameter can cause the great changes of output parameter, this input parameter is responsive for this output parameter so;

(f) if the great changes of input parameter can cause the very little variation of output parameter, this input parameter is exactly insensitive for this output parameter so;

Then,, set up the computing formula that embodies above fuzzy rule, calculate the character numerical value S of each input parameter of reflection each output parameter sensitivity from the notion of Euclidean distance and vector space;

$T_k=\underset{1}{\overset{z}{\underset{i\≠l}{\mathrm{\Σ}}}}\frac{d(y_{\mathrm{ij}},y_{\mathrm{lj}})}{d_k^{\′}(X_i,X_l)}$

(2)

$S_k=\frac{\underset{k\∈\{1,...,n\}}{\max }\left(T_k\right)-T_k}{\underset{k\∈\{1,...,n\}}{\max }\left(T_k\right)-\underset{k\∈\{1,...,n\}}{\min }\left(T_k\right)}$

(3)

In the formula, $d_k^{\′}(X_i,X_l)=\sqrt{d^2(X_i,X_l)-d_k^2(X_i,X_l)}$

D (X _i, X ₁) be input vector X _iWith X ₁Between Euclidean distance, d _k(X _i, X ₁) be d (X _i, X ₁) at x _kAxial projection, d (y _Ij, y _1j) be j output parameter y _iWith y ₁Between Euclidean distance; S _kBig more, output parameter y then _jTo input parameter x _kSensitivity high more;

(5) degree of agreement character numerical value and sensitivity character numerical value are combined, obtain reflecting the character numerical value of input parameter and output parameter degree in close relations: degree of agreement character numerical value and sensitivity character numerical value are combined according to formula (4);

F _k＝g ₁·V _k(x _k，y _j)+g ₂·S _k k∈{1，…，n}，j∈{1，…，m} (4)

Utilize two kinds of methods to determine weight coefficient g in the formula (4) ₁And g ₂Method 1 is according to V _kAnd S _kThe coefficient of variation calculate their weight coefficient, be designated as respectively

With

Subscript " 1 " representative method 1, its computing formula are formula (5) and formula (6); Method 2 calculates weight coefficient according to the deviation maximization principle

With

Subscript " 2 " representative method 2, its computing formula are formula (7) and formula (8); The weight coefficient that more than calculates carries out normalization according to formula (9), weight coefficient g ₁And g ₂Be the algebraic mean value that two kinds of methods are calculated weight coefficient, determine by formula (10) and formula (11);

$g_{11}^{*}=\frac{\sqrt{\frac{1}{n-1}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{({\mathrm{VA}}_k-\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{VA}}_k)}^2}}{\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{VA}}_k}$

(5)

$g_{21}^{*}=\frac{\sqrt{\frac{1}{n-1}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{(S_k-\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{S}_k)}^2}}{\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{S}_k}$

(6)

$g_{12}^{*}=\frac{\underset{1}{\underset{i\&NotEqual;k}{\overset{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C200610147213E00161.png"\; state="\{\{state\}\}">n</figure-callout>}}{\mathrm{\&Sigma;}}}}|{\mathrm{VA}}_i-{\mathrm{VA}}_k|}{\sqrt{{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|{\mathrm{VA}}_i-{\mathrm{VA}}_k|\right)}^2+{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|S_i-S_k|\right)}^2}}$

(7)

$g_{22}^{*}=\frac{\underset{1}{\underset{i\&NotEqual;k}{\overset{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C200610147213E00161.png"\; state="\{\{state\}\}">n</figure-callout>}}{\mathrm{\&Sigma;}}}}|S_i-S_k|}{\sqrt{{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|{\mathrm{VA}}_i-{\mathrm{VA}}_k|\right)}^2+{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|S_i-S_k|\right)}^2}}$

(8)

$g_{11}=\frac{g_{11}^{*}}{g_{11}^{*}+g_{21}^{*}}$ $g_{21}=\frac{g_{21}^{*}}{g_{11}^{*}+g_{21}^{*}}$ $g_{12}=\frac{g_{12}^{*}}{g_{12}^{*}+g_{22}^{*}}$ $g_{22}=\frac{g_{22}^{*}}{g_{12}^{*}+g_{22}^{*}}$

(9)

${\mathrm{<figure-callout\; id="1"\; label="g"\; filenames="C200610147213E00161.png"\; state="\{\{state\}\}">g</figure-callout>}}_1=\frac{1}{2}(g_{11}+g_{12})$

(10)

$g_2=\frac{1}{2}(g_{21}+g_{22})$

(11)

With weight coefficient g ₁And g ₂Substitution formula (4) has just calculated the character numerical value F that reflects input parameter and output parameter degree in close relations;

(6) according to level of intimate character numerical value size order, nerve network input parameter is screened: level of intimate character numerical value F _k, big more, output parameter y _jWith input parameter x _kDegree of correlation just big more; All F values are pressed descending order arrange, then input parameter and this output parameter relation of F value correspondence more in front are close more, should keep more when input parameter is screened; According to the actual needs of neural network, remove the Several Parameters that comes the back, thereby realize the screening of nerve network input parameter.

Description of drawings

Fig. 1 is the input space and output region graph of a relation.

Embodiment

Below in conjunction with specific embodiment the present invention is further elaborated.

The nerve network input parameter screening method that utilization the present invention is based on fuzzy logic is the neural network model that 18 non-weaving cloth samples are set up structural parameters and ultimate strength relation, carries out according to the steps in sequence among the present invention.

(1) obtains the neural net model establishing desired data

Set up a neural network model for the relation of non-weaving cloth structural parameters and ultimate strength, obtain following data: fibre length, fibre fineness, porosity, weight uniformity, thickness, weight per unit area, fiber volume density and ultimate strength.Wherein, the first seven is the non-weaving cloth structural parameters, the input parameter of neural network just, and ultimate strength is the output parameter of neural network.

(2) input and output parameter to neural network carries out pre-service

The relevant structural parameters and the ultimate strength of 18 non-weaving cloth samples see Table 1.All data normalizations are arrived between-1 and 1.

(3) calculate the character numerical value that reflects experimental data variation tendency and expertise degree of agreement

Calculate degree of agreement character numerical value V according to formula (1).The value of relational index R sees Table 2 in the formula (1).The degree of agreement character numerical value V that calculates is in table 3.

(4) calculate the character numerical value of reflection input parameter to the output parameter sensitivity

Calculate sensitivity character numerical value S according to formula (2) and formula (3).The sensitivity character numerical value S that calculates is in table 3.

(5) degree of agreement character numerical value and sensitivity character numerical value are combined, obtain reflecting the character numerical value of input parameter and output parameter degree in close relations

Calculate weight coefficient g according to formula (5) to formula (11) ₁And g ₂, calculate level of intimate character numerical value F according to formula (4).Weight coefficient that calculates and level of intimate character numerical value F are in table 3.

(6) according to level of intimate character numerical value size order, nerve network input parameter is screened

By table 3 as seen, according to the ordering of level of intimate character numerical value F, the level of intimate of structural parameters and ultimate strength relation is fiber volume density, fibre fineness, weight uniformity, porosity, fibre length, weight per unit area, thickness in proper order.According to the needs of building neural network, keep the input parameter of preceding 5 structural parameters as neural network.

Set up neural network as input and output parameter respectively with these 5 structural parameters and ultimate strength.This neural network is made up of an input layer, a hidden layer and an output layer.Input layer has 5 neurons, and hidden layer has 2 neurons, and output layer has 1 neuron.The transport function of hidden neuron adopts tangent Sigmoid function, and the neuronic transport function of output layer adopts linear function.In turn as test data, all the other 17 groups of data utilize error backpropagation algorithm that neural network is carried out training and testing as training data with every group of data.Table 4 has provided the predicted value and the predicated error of test data.

The computing formula of fibre diameter predicated error is in the table 4

By table 4 as seen, for these 18 non-weaving cloth samples, ultimate strength predicted value and measured value coincide fairly goodly, and the absolute value maximum of predicated error is no more than 10%, and the consensus forecast error is-0.88% only, illustrate that the neural network of being set up passed through test.Present embodiment shows, the nerve network input parameter screening method based on fuzzy logic of the present invention can be quickly and easily screens the input parameter of neural network, and the neural network that the screening back is set up is small scale not only, and the precision of prediction height.The present invention is specially adapted to the less neural net model establishing problem of sample size, also can be used for the screening of input parameter in other modeling methods, thereby has more wide application prospect.

The predicted value of table 4 test data and predicated error

Claims (1)

1. the nerve network input parameter screening method based on fuzzy logic is characterized in that this method comprises the steps:

(1) obtain the neural net model establishing desired data: this method is that the relation of non-weaving cloth structural parameters and ultimate strength is set up a neural network model, must obtain following data: fibre length, fibre fineness, porosity, weight uniformity, thickness, weight per unit area, fiber volume density and ultimate strength, wherein, the first seven is the non-weaving cloth structural parameters, the input parameter of neural network just, ultimate strength is the output parameter of neural network;

(2) input and output parameter to neural network carries out pre-service: in order to eliminate the difference of all kinds of parameter yardsticks aspect, input and output parameter all be normalized between-1 and 1;

(3) calculate the character numerical value of reflection experimental data variation tendency and expertise degree of agreement: the degree of agreement character numerical value is to be that output parameter calculates with respect to the variation tendency of input parameter and the degree of agreement of expertise in the experimental data according to experimental data and expertise mutual relationship;

If X _s=(x _S1, x _S2..., x _Sk..., x _Sn) ^TBe the input vector of neural network, Y _s=(y _S1, y _S2..., y _Sj..., y _Sm) ^TOutput vector for neural network; S sample s ∈ of subscript " s " expression 1 ..., i ..., 1 ..., z};

With domain y _jOn average be divided into t interval C _Jp, p ∈ 1 ..., t-1} is according to output parameter y _jInterval C _JpConstruct input parameter x _kCorresponding interval A _Kp

Set up following fuzzy rule:

(a) if certain input parameter x _kIncrease certain output parameter y _jAlso corresponding increase, the pass coefficient value R (x between them so _k, y _j) be+1;

(b) if certain input parameter x _kIncrease certain output parameter y _jCorresponding reducing, the pass coefficient value R (x between them so _k, y _j) be-1;

(c) if certain input parameter x _kReduce certain output parameter y _jCorresponding increase, the pass coefficient value R (x between them so _k, y _j) be-1;

(d) if certain input parameter x _kReduce certain output parameter y _jAlso corresponding reducing, the pass coefficient value R (x between them so _k, y _j) be+1;

Degree of agreement character numerical value V is calculated by formula (1):

$\left\{\begin{array}{c}{V}_k(x_k,y_j)=\frac{1}{t-1}\underset{p=1}{\overset{t-1}{\mathrm{\&Sigma;}}}{v}_p\\ \begin{array}{cc}{x}_{\mathrm{kp}}^{\inf }=\underset{s\&Element;\{1,...,z\}}{\min }\left\{x_{\mathrm{sk}}\right|y_{\mathrm{sj}}\&Element;C_{\mathrm{jp}}\}& x_{\mathrm{kp}}^{\sup }=\underset{s\&Element;\{1,...,z\}}{\max }\left\{x_{\mathrm{sk}}\right|y_{\mathrm{sj}}\&Element;C_{\mathrm{jp}}\}\end{array}\\ \mathrm{if}{I}_{\mathrm{kp}}=\mathrm{\&phi;},\left\{\begin{array}{c}{v}_p=\frac{1}{2}\left|R(x_k,y_j)\right|\&times;[1+R(x_k,y_j)],\mathrm{if}{x}_{\mathrm{kp}+1}^{\inf }\&GreaterEqual;x_{\mathrm{kp}}^{\sup }\\ v_p=\frac{1}{2}\left|R(x_k,y_j)\right|\&times;[1-R(x_k,y_j)],\mathrm{if}{x}_{\mathrm{kp}+1}^{\sup }\&le;x_{\mathrm{kp}}^{\inf }\end{array}\right.\\ \mathrm{if}{I}_{\mathrm{kp}}\&NotEqual;\mathrm{\&phi;},\left\{\begin{array}{c}{v}_p=\frac{1}{2}\left|R(x_k,y_j)\right|\&times;[1+R(x_k,y_j)]\&times;(1-\frac{\left|I_{\mathrm{kp}}\right|}{{|U}_{\mathrm{kp}}|}),\mathrm{if}{x}_{\mathrm{kp}+1}^{\sup }\&GreaterEqual;x_{\mathrm{kp}}^{\sup }\\ v_p=\frac{1}{2}\left|R(x_k,y_j)\right|\&times;[1-R(x_k,y_j)]\&times;(1-\frac{\left|I_{\mathrm{kp}}\right|}{{|U}_{\mathrm{kp}}|}),\mathrm{if}{x}_{\mathrm{kp}+1}^{\inf }\&le;x_{\mathrm{kp}}^{\inf }\end{array}\right.\end{array}\right.$

(1)

In the formula, R (x _k, y _j) be input parameter x _kWith output parameter y _jRelational index, v _pBe interval C _JpThe degree of agreement character numerical value, φ is an empty set; With

Be the interval A of difference _KpLower boundary and coboundary, I _KpAnd U _KpBe respectively interval A _KpAnd A _Kp+1Common factor and union, V _kBig more, output parameter y then _jWith respect to input parameter x _kThe variation tendency and the degree of agreement of expertise high more;

(4) calculate the character numerical value of reflection input parameter to the output parameter sensitivity: sensitivity character numerical value S concerns to be that the neural network output parameter calculates the sensitivity of nerve network input parameter each other according to experimental data;

Set up following fuzzy rule:

(e) if the very little variation of input parameter can cause the great changes of output parameter, this input parameter is responsive for this output parameter so;

(f) if the great changes of input parameter can cause the very little variation of output parameter, this input parameter is exactly insensitive for this output parameter so;

Then,, set up the computing formula that embodies above fuzzy rule, calculate the character numerical value S of each input parameter of reflection each output parameter sensitivity from the notion of Euclidean distance and vector space;

$T_k=\underset{1}{\overset{z}{\underset{i\&NotEqual;l}{\mathrm{\&Sigma;}}}}\frac{d(y_{\mathrm{ij}},y_{\mathrm{lj}})}{d_k^{\&prime;}(X_i,X_l)}$

(2)

$S_k=\frac{\underset{k\&Element;\{1,...,n\}}{\max }\left(T_k\right)-T_k}{\underset{k\&Element;\{1,...,n\}}{\max }\left(T_k\right)-\underset{k\&Element;\{1,...,n\}}{\min }\left(T_k\right)}$

(3)

In the formula, $d_k^{\&prime;}(X_i,X_l)=\sqrt{d^2(X_i,X_l)-d_k^2(X_i,X_l)}$

D (X _i, X _l) be input vector X _iWith X _lBetween Euclidean distance, d _k(X _i, X _l) be d (X _i, X _l) at x _kAxial projection, d (y _Ij, y _Lj) be j output parameter y _iWith y _lBetween Euclidean distance; S _kBig more, output parameter y then _jTo input parameter x _kSensitivity high more;

(5) degree of agreement character numerical value and sensitivity character numerical value are combined, obtain reflecting the character numerical value of input parameter and output parameter degree in close relations: degree of agreement character numerical value and sensitivity character numerical value are combined according to formula (4);

F _k＝g ₁·V _k(x _k，y _j)+g ₂·S _k k∈{1，…，n}，j∈{1，…，m} (4)

Utilize two kinds of methods to determine weight coefficient g in the formula (4) ₁And g ₂Method 1 is according to V _kAnd S _kThe coefficient of variation calculate their weight coefficient, be designated as respectively With

, subscript " 1 " representative method 1, its computing formula are formula (5) and formula (6); Method 2 calculates weight coefficient according to the deviation maximization principle

With

, subscript " 2 " representative method 2, its computing formula are formula (7) and formula (8); The weight coefficient that more than calculates carries out normalization according to formula (9), weight coefficient g ₁And g ₂Be the algebraic mean value that two kinds of methods are calculated weight coefficient, determine by formula (10) and formula (11);

$g_{11}^{*}=\frac{\sqrt{\frac{1}{n-1}\underset{k=1}{\overset{n}{\mathrm{\&Sigma;}}}{({\mathrm{VA}}_k-\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{VA}}_k)}^2}}{\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{VA}}_k}$

(5)

$g_{21}^{*}=\frac{\sqrt{\frac{1}{n-1}\underset{k=1}{\overset{n}{\mathrm{\&Sigma;}}}{(S_k-\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\&Sigma;}}}{S}_k)}^2}}{\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\&Sigma;}}}{S}_k}$

(6)

$g_{12}^{*}=\frac{\underset{1}{\underset{i\&NotEqual;k}{\overset{n}{\mathrm{\&Sigma;}}}}|{\mathrm{VA}}_i-{\mathrm{VA}}_k|}{\sqrt{{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|{\mathrm{VA}}_i-{\mathrm{VA}}_k|\right)}^2+{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|S_i-S_k|\right)}^2}}$

(7)

$g_{22}^{*}=\frac{\underset{1}{\underset{i\&NotEqual;k}{\overset{n}{\mathrm{\&Sigma;}}}}|S_i-S_k|}{\sqrt{{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|{\mathrm{VA}}_i-{\mathrm{VA}}_k|\right)}^2+{\left(\underset{1}{\overset{n}{\underset{i\&NotEqual;k}{\mathrm{\&Sigma;}}}}|S_i-S_k|\right)}^2}}$

(8)

$g_{11}=\frac{g_{11}^{*}}{g_{11}^{*}+g_{21}^{*}}$ $g_{21}=\frac{g_{21}^{*}}{g_{11}^{*}+g_{21}^{*}}$ $g_{12}=\frac{g_{12}^{*}}{g_{12}^{*}+g_{22}^{*}}$ $g_{22}=\frac{g_{22}^{*}}{g_{12}^{*}+g_{22}^{*}}$

(9)

$g_1=\frac{1}{2}(g_{11}+g_{12})$

(10)

$g_2=\frac{1}{2}(g_{21}+g_{22})$

(11)

With weight coefficient g ₁And g ₂Substitution formula (4) has just calculated the character numerical value F that reflects input parameter and output parameter degree in close relations;

(6) according to level of intimate character numerical value size order, nerve network input parameter is screened: level of intimate character numerical value F _k, big more, output parameter y _jWith input parameter x _kDegree of correlation just big more; All F values are pressed descending order arrange, then input parameter and this output parameter relation of F value correspondence more in front are close more, should keep more when input parameter is screened; According to the actual needs of neural network, remove the Several Parameters that comes the back, thereby realize the screening of nerve network input parameter.

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