CN102999693A - Pre-judging method of characteristics of nuclear component material driven by 252Cf source - Google Patents

Pre-judging method of characteristics of nuclear component material driven by 252Cf source Download PDF

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CN102999693A
CN102999693A CN2012103860053A CN201210386005A CN102999693A CN 102999693 A CN102999693 A CN 102999693A CN 2012103860053 A CN2012103860053 A CN 2012103860053A CN 201210386005 A CN201210386005 A CN 201210386005A CN 102999693 A CN102999693 A CN 102999693A
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neutron
thickness
nuclear component
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CN102999693B (en
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杨帆
魏彪
冯鹏
米德伶
任勇
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Chongqing University
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Abstract

The invention discloses a pre-judging method of characteristics of a nuclear component material driven by a 252Cf source. The method mainly comprises, aiming at thickness and material information of the nuclear component material, pre-judging work by means of a time domain related model and signal processing method. The time domain related model and signal processing method comprises three main aspects: intercepting the thickness of an unknown nuclear component material by a neutron peak position in a source-probe inter-time domain related function; analyzing the ascending edge and descending edge of the neutron peak to put forward a neutron ratio method, and eliminating interference of a non-nuclear material and initially judging the material of the nuclear component; and determining the material of the unknown nuclear component and enhancing the judging result by means of gamma count value of the source-probe inter-time domain related function. According to the method, a better pre-judging effect of the nuclear component material is obtained due to the unprecedented non-nuclear material eliminating capacity and judging capacity for material and thickness characteristics of the nuclear component.

Description

A kind of based on 252The nuclear component material characteristics that the Cf source drives is differentiated method in advance
Technical field
The invention belongs to digital signal processing and verify technical field, relate to a kind of based on 252The unknown nuclear component material that the Cf source drives is differentiated method in advance.
Background technology
Verify nuclear material in the technical field/nuclear weapon recognition system (Nuclear Material Identified System, NMIS), i.e. nuclear material checking system, its aim is to measure the characteristic parameter of nuclear material, thereby infers its use field.Its critical function is the enrichment (enrichment of nuclear material is the important symbol of distinguishing weapongrade and civilian level, and can infer therefrom that it has state's nuclear industry level) that detects nuclear material.From obtaining the approach of nuclear material radiation signal, verify technology path and usually be divided into passive type and active two kinds.Be limited to uranium (U, Uranium) material spontaneous radiation energy is lower, measures for its verification technology formula of need taking the initiative, and namely causes the chain reaction of nuclear material by extrinsic motivated source Implantation Energy, obtain necessary information by surveying its fission product, be called again source drive-type measuring method.
The source drives noise analysis system and verifies principle as shown in Figure 1.At first, the spontaneous fission source in the #1 passage 252Cf is for driving neutron source, and the spontaneous fission neutron of its outgoing is incident to nuclear component to be measured and brings out chain reaction.The chain reaction meeting produces some neutrons and gamma-rays, and is caught by the detector of #2 and #3 passage. 2524 spontaneous fission neutrons and 6 γ photons are emitted in the average each fission in Cf source.The spontaneous fission neutron enters and brings out a series of fission neutrons that bring out of chain reaction generation in the nuclear material to be measured, and after namely nuclear material to be measured " was excited ", the neutron that carries its relevant information was detected device and surveys, and obtains multichannel pulsed neutron signal.Pulsed neutron signal by source driving method obtains after NMIS time-domain signal analyzing and processing, can obtain corresponding time domain coherent signal label.Tradition NMIS time domain coherent signal particle counting forms as shown in Figure 2.The spike that left side slope is larger among the figure is the direct projection γ photon that is detected at first, and it has directly passed nuclear component to be measured and has not passed through any collision; Milder second peak region is respectively by scattering γ photon, direct projection neutron, scattered neutron with bring out fission neutron and form behind a trough, and they roughly are arranged in order on time shaft as marking among the figure.Direct projection neutron, scattered neutron and to bring out generation mechanism and the energy of fission neutron all different, the time that therefore arrives detector is also variant, and has caused the broadening on the time domain.Obviously, between source-detector signal the time domain related function in the count value of bringing out the time interval of fission neutron (usually getting 20-100ns) to tested 235There is susceptibility in the enrichment of U material, along with the enrichment of nuclear material raises and increases, so can utilize this characteristic of nuclear signal time domain coherent signal to identify the nuclear material enrichment.
Although comparatively complete for the mathematical analysis of system correlation function in theory, yet only limit to the situation of relative ideal.The principle of work of NMIS has determined that the on-the-spot fundamental function of obtaining must be compared with calibration value and just can reach a conclusion---obviously, traditional NMIS can't learn that UUT is nuclear component, whether is worth measuring, and just mechanically it " is used as " signal that nuclear material produces, and applies mechanically the regular time interval and carry out enrichment and judge.So not only with sizable blindness, may waste time and the system resource of a large amount of preciousnesses, and may introduce very large error, finally affect identification and the sentence read result of NMIS, cause serious consequence.Fig. 3 is that NMIS measures source-detector cross correlation function simulation result under lower several different situations, comprising:
Figure 2012103860053100002DEST_PATH_IMAGE001
Different material comprises nuclear material and non-nuclear material;
Figure 947735DEST_PATH_IMAGE002
Different materials thickness;
Figure DEST_PATH_IMAGE003
Different IPs material enrichment.For the problem of outstanding wish explanation, among the figure certain cut ridge have been done at the γ peak and processed, emphasis is the peak-to-peak difference of neutron relatively.As can be seen from the figure, even in muting situation, no matter be the time of amplitude, downtrending or the appearance at neutron peak, between nuclear material and non-nuclear material, between different enrichment nuclear material so that the different-thickness storeroom all different, mutual tied up in knots.If differentiate enrichment according to traditional NMIS by integral way, probably will be wherein some non-nuclear material be used as nuclear material and judge, or with equal enrichment and the different nuclear material of thickness is judged as the different nuclear material of enrichment, etc.As seen, the judgement that relies on merely the integrated value of time domain related function to carry out enrichment exists its essential defective.
Therefore, a kind of material pre-judging method based on γ and the resolution of neutron time domain waveform correlation is proposed, utilize its character to unknown nuclear component to carry out anticipation, the nuclear component material characteristics that can reject garbage before NMIS running and obtain nuclear component material characteristics parameter is differentiated method in advance, just becomes institute of the present invention problems of concern.
Summary of the invention
The technical matters that the present invention solves is the interference of how to obtain unknown nuclear component thickness information, removing non-nuclear material, determine unknown nuclear component material characteristics, judge material thickness and material, thus overcome existing system without anticipation mechanism, be subject to non-nuclear material and disturb and the single shortcoming of characteristic parameter.
Consider characteristics and the character of NMIS and neutron pulse signal, the purpose of this invention is to provide a kind of based on 252The nuclear component material characteristics that the Cf source drives is differentiated method in advance, does corresponding neutron peak, the extraction of γ peak-to-peak signal and analysis by the cross covariance signal that traditional NMIS is obtained, and extracts unknown nuclear component material, thickness, and rejects the interference of non-nuclear material.The method is abundant to the information utilization, and anti-non-nuclear material interference performance is strong and can obtain the nuclear component material characteristics, makes source driving noise analysis and signal processing method based on the pulsed neutron signal reach higher precision and expand its range of application.
In order to reach above purpose, the present invention adopts following technical scheme: a kind of based on 252The nuclear component material characteristics that the Cf source drives is differentiated method in advance, at first, adopts 252The Cf source drives noise analysis method and series of standards material and sets up when count value nominal data storehouse, γ peak of the neutron peak position that can embody material thickness and material, neutron peak; Then, adopt 252The Cf source drives the noise analysis method UUT is carried out the when γ peak count value extraction of neutron peak position, neutron peak; At last, three numerical value and the described nominal data storehouse of extracting compared and calculates the part materials characteristic parameter;
Described material characteristics parameter comprises thickness interpretation, the rejecting of non-nuclear material, material interpretation and recognition result reinforcement; Wherein:
(1) thickness interpretation: obtain the nuclear component thickness information by source-detector time domain related function neutron peak time point analysis;
Figure 989509DEST_PATH_IMAGE001
Its source of pulsed neutron calculated signals by nuclear material that the nuclear weapon checking system based on source drive-type noise analysis approach is obtained-detector cross covariance function; Raw data is divided into
Figure 383626DEST_PATH_IMAGE004
Piece, and
Figure 965786DEST_PATH_IMAGE006
Be point sometime on the time shaft in a certain blocks of data, the computing formula that any nothing of the pulsed neutron source of employing-detector cross covariance function is estimated partially is:
Figure DEST_PATH_IMAGE007
Thereby the nothing of whole cross covariance signal is estimated as partially:
Figure 406257DEST_PATH_IMAGE008
Wherein
Figure DEST_PATH_IMAGE009
Represent a certain road signal
Figure 353353DEST_PATH_IMAGE010
Complex conjugate,
Figure DEST_PATH_IMAGE011
It then is another road detector signal;
Figure 184168DEST_PATH_IMAGE012
Be data block length, with the discrete expression of counting, because sampling interval is 1ns, then dot spacing is 1ns; Be time delay; And
Figure 507702DEST_PATH_IMAGE014
It is total number of data block;
Extract
Figure DEST_PATH_IMAGE015
The neutron peak, from physical model essence, be seen as the combination that first half scattering γ photon, direct projection neutron, scattered neutron and latter half bring out fission neutron.Experimental results show that, first half is that whether the radioactive nucleus material is also insensitive for material for the neutron peak time of occurrence, and only relevant with the stroke of particle in material---material is thicker, the stroke of particle is larger, the three particularly direct projection neutron and scattered neutron to arrive the required time of detector just longer;
In fact be a time series that is formed by the time point of different amplitudes, comprise two parts in neutron peak and γ peak.γ peak and neutron peak always order occur and are non-interfering.Therefore, only need utilize the time interval method to incite somebody to action
Figure 737324DEST_PATH_IMAGE015
In second peak extract, namely obtain required neutron peak image and value;
Figure 474335DEST_PATH_IMAGE003
By 252Cf source drive-type noise analysis system obtains its pulsed neutron signal that produces and carries out correlation analysis in time domain for the standard nuclear material under different-thickness, produce a series of neutrons peak nominal data, as the part in the reference standard that obtains material thickness and nominal data storehouse;
Figure 935404DEST_PATH_IMAGE016
Accurately the time of location neutron peak point appearance, itself and material thickness nominal data storehouse are compared, obtained the thickness of unknown nuclear component material;
(2) non-nuclear material rejecting and nuclear component material are tentatively judged: the material of rejecting non-nuclear material and preliminary interpretation nuclear component by neutron peak accounting method;
Based on the atomic nuclear physics experimental technique, from the source fission event, by fission event conditional probability, fission chain correlated condition probability events of equal probability, infer as drawing a conclusion:
A. gamma-ray count value is subject to the atomic number impact of material thickness and material simultaneously, and is relevant with atomic number in the similar situation of thickness;
B. the count value at neutron peak changes along with the variation of material and thickness, but nuclear material is owing to there is the existence of bringing out fission neutron, so the more non-nuclear material of its negative edge obviously slows down, and namely the negative edge neutron counting ratio that accounts for tale raises; Accordingly, because of without bringing out the existence of fission neutron, non-nuclear material negative edge is without above-mentioned feature;
Figure 295289DEST_PATH_IMAGE002
The neutron peak that extracts the cross covariance function between source-detector carries out rise/fall along analysis, introduces a new model identification parameter herein r, i.e. pulse rise/fall is along proportion:
Figure DEST_PATH_IMAGE017
In the formula
Figure 508096DEST_PATH_IMAGE018
The rising edge integrated value,
Figure DEST_PATH_IMAGE019
Be the negative edge integrated value, and
Figure 338517DEST_PATH_IMAGE020
The time interval of expression neutron peak rising edge,
Figure DEST_PATH_IMAGE021
Expression neutron peak negative edge time interval,
Figure 299782DEST_PATH_IMAGE022
It is the cross covariance function of source channels and probe access;
Figure 28704DEST_PATH_IMAGE003
According to nuclear physics and particle handling technique relative theory, determine neutron peak each integrating range of accounting method.Consider and bring out just dominate of fission neutron in the certain hour interval behind neutron peak, therefore the start time of negative edge is taken as 10ns behind the peak point, and integrating range is 80ns.Similarly, the interval of rising edge is made as 4ns, and terminal point is taken as 2ns place before the neutron peak point.If suppose time to peak point be t 0, then following formula can be expressed as:
Figure DEST_PATH_IMAGE023
Figure 45202DEST_PATH_IMAGE016
Standard nuclear component pulsed neutron signal for unlike material carries out correlation analysis in time domain, draws it in neutron peak accounting value rOn obvious difference, according to rValue is classified, as the part in nominal data storehouse;
Figure 730130DEST_PATH_IMAGE024
To calculate gained rValue and nominal data storehouse are compared, and reject the interference of non-nuclear material, and preliminary interpretation nuclear component material;
(3) the nuclear component material clearly reaches recognition result and strengthens: by γ peak counting diagnostic method further front two ones of identification fail the material nuance accurately distinguished, and strengthen recognition effect;
According to identification resulting materials thickness in the step (1) cross covariance function of different-thickness material is classified, and therefrom extract the count value of γ peak point;
Figure 390098DEST_PATH_IMAGE002
Standard nuclear component pulsed neutron signal for the same thickness unlike material carries out correlation analysis in time domain, draws its obvious difference on the count value of γ peak point, classifies according to count value, as the part in nominal data storehouse;
Compared in count value and the nominal data storehouse of actual measurement γ peak point, obtain the nuclear component material information;
Figure 313503DEST_PATH_IMAGE003
The information of obtaining in material information and the step (2) is verified, further distinguished dissimilar, thickness nuclear component.
Described signals collecting frequency can be 1GHz, can certainly be 500MHz or other frequencies.
The length of described data block is 1024 bytes, can certainly get other length such as 256,512,2048.
Compared to existing technology, the present invention has following beneficial effect:
1, traditional NMIS can't learn that unknown component is nuclear component, whether is worth measuring, should comparing with which nominal data storehouse, and just mechanically it " is used as " signal that nuclear material produces, and applies mechanically the regular time interval and carry out follow-up Discern and judge.Therefore what the present invention took the lead in adopting differentiates mechanism and method and is not increasing the weight of the NMIS system burden and do not changing the interference of having rejected non-nuclear material in the situation of system architecture this in advance.
2, the position is identified and interpretation owing to time domain related function neutron peak between source-detector is occurred, NMIS can be extracted from the traditional characteristic label differ from the traditional characteristic value, unknown this brand-new eigenwert of nuclear component material geometric thickness, thereby geometric thickness and nominal data storehouse are mapped, clear and definite database comparison other has reduced the corresponding inaccurate possibility that causes erroneous judgement of factor data bank.
3, determine the material of unknown nuclear component by neutron peak accounting method and γ peak counting diagnostic method, extract and the signal intractability thereby alleviate subsequent characteristics.The present invention has additionally segmented the kind of nuclear component material except rejecting non-nuclear material and disturb and obtained the parameter such as unknown nuclear component thickness, thereby more accurate for obtaining, comprehensively verify the result useful information is provided.
Description of drawings
Fig. 1 is 252The Cf source drives noise analysis and signal processing system synoptic diagram;
Fig. 2 is that source-detector time domain coherent signal particle forms synoptic diagram;
Fig. 3 is different material and different-thickness time domain related function neutron peak comparison diagram;
Fig. 4 is that material of the present invention is differentiated process flow diagram in advance;
Fig. 5 is that embodiment of the invention thickness is that 2cm different materials neutron peak time of occurrence compares;
Fig. 6 is that embodiment of the invention thickness is that 0.95cm different materials neutron peak time of occurrence compares;
Fig. 7 is that embodiment of the invention thickness is that 0.45cm different materials neutron peak time of occurrence compares;
Fig. 8 is relatively histogram of the final recognition result of the embodiment of the invention.
Embodiment
Below by embodiment the present invention is described in further detail, therefore do not limit the present invention among the described scope of embodiments.
Referring to Fig. 4, a kind of based on 252The nuclear component material characteristics that the Cf source drives is differentiated method in advance: at first, adopt 252The Cf source drives noise analysis method and series of standards material and sets up when count value nominal data storehouse, γ peak of the neutron peak position that can embody material thickness and material, neutron peak; Then, adopt 252The Cf source drives the noise analysis method UUT is carried out the when γ peak count value extraction of neutron peak position, neutron peak; At last, three numerical value and the described nominal data storehouse of extracting compared and calculates the part materials characteristic parameter;
Described material characteristics parameter comprises thickness interpretation, the rejecting of non-nuclear material, material interpretation and nuclear component Material Identification, and concrete steps are:
(1) obtaining of thickness information: obtain the nuclear component thickness information by source-detector time domain related function neutron peak time point analysis.(referring to Fig. 1) is with spontaneous fission source 252Cf is for driving neutron source (#1 passage), and the spontaneous fission neutron of its outgoing is incident to nuclear component to be measured and brings out chain reaction; The chain reaction meeting produces some neutrons and gamma-rays, and is caught by the detector of #2 and #3 passage; 2524 spontaneous fission neutrons and 6 γ photons are emitted in the average each fission in Cf source.The spontaneous fission neutron enters and brings out a series of fission neutrons that bring out of chain reaction generation in the nuclear material to be measured, and after namely nuclear material to be measured " was excited ", the neutron that carries its relevant information was detected device and surveys, and obtains multichannel pulsed neutron signal; Pulsed neutron signal by the source driving method acquisition; The neutron pulse data are gathered the time distribution that obtains neutron source and counted by the neutron detection that the unknown nuclear material that neutron source excites produces, the neutron pulse sequence that the form that the described time distributes is comprised of " 0 " and " 1 "; Subsequently the neutron pulse sequence that collects is carried out the covariance computing and obtained cross covariance function; Thereby the position of extracting the appearance of cross covariance function neutron peak point obtains thickness information.
(2) non-nuclear material rejecting and nuclear component material are tentatively judged: the material of rejecting non-nuclear material and preliminary interpretation nuclear component by neutron peak accounting method.According to following formula:
Figure 193734DEST_PATH_IMAGE026
In the formula
Figure 631669DEST_PATH_IMAGE028
The rising edge integrated value,
Figure 239237DEST_PATH_IMAGE030
Be the negative edge integrated value, and
Figure 649489DEST_PATH_IMAGE032
The time interval of expression neutron peak rising edge,
Figure 762939DEST_PATH_IMAGE034
Expression neutron peak negative edge time interval,
Figure 376585DEST_PATH_IMAGE036
It is the cross covariance function of source channels and probe access.
Standard nuclear component pulsed neutron signal for unlike material carries out correlation analysis in time domain, draws it in neutron peak accounting value rOn obvious difference, according to rValue is classified, as the part in nominal data storehouse;
To calculate gained rValue and nominal data storehouse are compared, and reject the interference of non-nuclear material, and preliminary interpretation nuclear component material;
(3) the nuclear component material clearly reaches recognition result and strengthens: by γ peak counting diagnostic method further front two ones of identification fail the material nuance accurately distinguished, and strengthen recognition effect.
Figure 600893DEST_PATH_IMAGE038
According to identification resulting materials thickness in the step (1) cross covariance function of different-thickness material is classified, and therefrom extract the count value of γ peak point;
Figure 600073DEST_PATH_IMAGE040
Standard nuclear component pulsed neutron signal for the same thickness unlike material carries out correlation analysis in time domain, draws its obvious difference on the count value of γ peak point, classifies according to count value, as the part in nominal data storehouse;
Figure 71375DEST_PATH_IMAGE040
Compared in count value and the nominal data storehouse of actual measurement γ peak point, obtain the nuclear component material information;
Figure 483901DEST_PATH_IMAGE042
The information of obtaining in material information and the step (2) is verified, further distinguished dissimilar, thickness nuclear component.
Described signals collecting frequency can be 1GHz, can certainly be 500MHz or other frequencies.
The length of described data block is 1024 bytes, can certainly get other length such as 256,512,2048.
Present embodiment enrichment exemplary aspect adopts annular cast as unknown nuclear component, and it is 90.15% and 93.15% U that its material is respectively Fe, Au and enrichment, and thickness is respectively 0.45cm, 0.95cm and 2cm.The flow process that step (1) is mentioned as shown in Figure 4.The source that obtains-detector time domain related function is carried out the identification of neutron peak position, and then obtain the differentiation of the material related function image of different-thickness, such as Fig. 5, Fig. 6 and shown in Figure 7.Recognition result sees Table 1.
1 different materials neutron peak time point compares:
Figure DEST_PATH_IMAGE043
Described step (2) is carried out as follows: a. carries out the neutron peak to the source of 12 kinds of experiment samples of unlike material and thickness-detector time domain related function and extracts and analytical work; B. calculate neutron peak accounting between the different experiments sample, and the relatively difference between them, thereby non-nuclear material rejected; Accounting value in neutron peak is as shown in table 2 in different materials and the thickness situation.
Neutron peak accounting in table 2 different materials and the thickness situation rRelatively:
Figure 449583DEST_PATH_IMAGE044
After this carry out the counting discriminatory analysis of stack pile material γ peak according to the principle shown in the step (3), it the results are shown in Table 3.Compare with nominal data subsequently, obtain unknown nuclear component material and the first two steps result is strengthened.Shown in Fig. 8 is relatively histogram of final recognition result.
Table 3 different materials γ peak count value compares:
Figure DEST_PATH_IMAGE045
After above-mentioned calculating is complete, with the material feature fusion of acquisition in the thickness characteristics information that obtains in the step 1 and the step 2,3, obtain the pre-differentiation result of the unknown nuclear component character of comprehensive embodiment.
Explanation is at last, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although with reference to preferred embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not breaking away from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (1)

  1. One kind based on 252The nuclear component material characteristics that the Cf source drives is differentiated method in advance, it is characterized in that, at first, adopts 252The Cf source drives noise analysis method and series of standards material and sets up when count value nominal data storehouse, γ peak of the neutron peak position that can embody material thickness and material, neutron peak; Then, adopt 252The Cf source drives the noise analysis method UUT is carried out the when γ peak count value extraction of neutron peak position, neutron peak; At last, three numerical value and the described nominal data storehouse of extracting compared and calculates the part materials characteristic parameter;
    Described material characteristics parameter comprises thickness interpretation, the rejecting of non-nuclear material, material interpretation and recognition result reinforcement; Wherein:
    (1) material thickness interpretation: obtain the nuclear component thickness information by source-detector time domain related function neutron peak time point analysis;
    Its source of pulsed neutron calculated signals by nuclear material that the nuclear weapon checking system based on source drive-type noise analysis approach is obtained-detector cross covariance function; To be divided into by the time domain pulse sequence signal that detector collects Piece, and Be point sometime on the time shaft in a certain blocks of data, the computing formula that any nothing of the pulsed neutron source of employing-detector cross covariance function is estimated partially is:
    Figure DEST_PATH_IMAGE008
    Thereby the nothing of whole cross covariance signal is estimated as partially:
    Wherein
    Figure DEST_PATH_IMAGE012
    Represent a certain road signal
    Figure DEST_PATH_IMAGE014
    Complex conjugate,
    Figure DEST_PATH_IMAGE016
    It then is another road detector signal;
    Figure DEST_PATH_IMAGE018
    Be data block length, with the discrete expression of counting, because sampling interval is 1ns, then dot spacing is 1ns; Be time delay; And
    Figure DEST_PATH_IMAGE022
    It is total number of data block;
    Extract The neutron peak:
    Figure 710247DEST_PATH_IMAGE026
    Comprise two parts in neutron peak and γ peak; Utilize the time interval method to incite somebody to action
    Figure 689705DEST_PATH_IMAGE026
    In second peak extract, namely obtain required neutron peak image and value;
    Figure DEST_PATH_IMAGE028
    By 252Cf source drive-type noise analysis system obtains its pulsed neutron signal that produces and carries out correlation analysis in time domain for the standard nuclear material under different-thickness, produce a series of neutrons peak nominal data, as the part in the reference standard that obtains material thickness and nominal data storehouse;
    Figure DEST_PATH_IMAGE030
    Accurately the time of the neutron peak point appearance of location nuclear component, itself and material thickness nominal data storehouse are compared, obtained the thickness of nuclear component material;
    (2) non-nuclear material rejecting and nuclear component material are tentatively judged: by following formula, namely be called the material that neutron peak accounting method is rejected non-nuclear material and preliminary interpretation nuclear component;
    Figure DEST_PATH_IMAGE032
    In the formula
    Figure DEST_PATH_IMAGE034
    The rising edge integrated value,
    Figure DEST_PATH_IMAGE036
    Be the negative edge integrated value, and
    Figure DEST_PATH_IMAGE038
    The time interval of expression neutron peak rising edge,
    Figure DEST_PATH_IMAGE040
    Expression neutron peak negative edge time interval,
    Figure DEST_PATH_IMAGE042
    It is the cross covariance function of source channels and probe access;
    Standard nuclear component pulsed neutron signal for unlike material carries out correlation analysis in time domain, draws it in neutron peak accounting value rOn obvious difference, according to rValue is classified, as the part in nominal data storehouse;
    To calculate gained rValue and nominal data storehouse are compared, and reject the interference of non-nuclear material, and preliminary interpretation nuclear component material;
    (3) the nuclear component material clearly reaches recognition result and strengthens: further identify first two steps by γ peak counting diagnostic method and fail the material nuance accurately distinguished, and strengthen recognition effect;
    Figure 282491DEST_PATH_IMAGE002
    According to identification resulting materials thickness in the step (1) cross covariance function of different-thickness material is classified, and therefrom extract the count value of γ peak point;
    Figure 241482DEST_PATH_IMAGE024
    Standard nuclear component pulsed neutron signal for the same thickness unlike material carries out correlation analysis in time domain, draws its obvious difference on the count value of γ peak point, classifies according to count value, as the part in nominal data storehouse;
    3. will survey count value and the nominal data storehouse of γ peak point and compare, obtain the nuclear component material information;
    4. the information of obtaining in material information and the step (2) is verified, further distinguished dissimilar, thickness nuclear component.
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CN105893779A (en) * 2016-04-29 2016-08-24 东北林业大学 Construction method of model for forecasting durability of polylactic acid-based ternary degradable compound material

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CN105893779A (en) * 2016-04-29 2016-08-24 东北林业大学 Construction method of model for forecasting durability of polylactic acid-based ternary degradable compound material
CN105893779B (en) * 2016-04-29 2018-09-07 东北林业大学 A kind of construction method of prediction polylactic acid base ternary degradable composite material durability model

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