Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435802
S. Blunt, K. Gerlach
It is well known that two or more radars operating in close proximity, at the same time, and in the same spectrum can severely interfere with one another despite the use of low cross-correlation waveforms. Recently, an approach was proposed called multistatic adaptive pulse compression (MAPC) based on a minimum mean-square error (MMSE) formulation which has been shown to suppress both range sidelobes and cross-correlation ambiguities to the level of the noise. This paper examines the performance of the MAPC approach under the effects of Doppler mismatch. It is demonstrated that for relatively high Doppler the MAPC approach experiences some Doppler-induced sidelobes around large targets yet is still substantially superior to the standard matched filter.
{"title":"Aspects of multistatic adaptive pulse compression","authors":"S. Blunt, K. Gerlach","doi":"10.1109/RADAR.2005.1435802","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435802","url":null,"abstract":"It is well known that two or more radars operating in close proximity, at the same time, and in the same spectrum can severely interfere with one another despite the use of low cross-correlation waveforms. Recently, an approach was proposed called multistatic adaptive pulse compression (MAPC) based on a minimum mean-square error (MMSE) formulation which has been shown to suppress both range sidelobes and cross-correlation ambiguities to the level of the noise. This paper examines the performance of the MAPC approach under the effects of Doppler mismatch. It is demonstrated that for relatively high Doppler the MAPC approach experiences some Doppler-induced sidelobes around large targets yet is still substantially superior to the standard matched filter.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127383313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435929
Jia Xu, Gang Li, Jun Li, Yingning Peng, X. Xia
This paper reports a low-complexity method for Doppler center estimation of synthetic aperture radar (SAR) based on inner product operation. Compared to the conventional correlation-based method, the optimal performance may be obtained but with a high computational efficiency. Besides, the problem of "spectrum splitting", trouble for existing inner product-based method, may also be well avoided. Last, the effectiveness of the proposed method is demonstrated using detailed performance analysis based on numerical experiments.
{"title":"An effective SAR Doppler center estimation method based on inner product","authors":"Jia Xu, Gang Li, Jun Li, Yingning Peng, X. Xia","doi":"10.1109/RADAR.2005.1435929","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435929","url":null,"abstract":"This paper reports a low-complexity method for Doppler center estimation of synthetic aperture radar (SAR) based on inner product operation. Compared to the conventional correlation-based method, the optimal performance may be obtained but with a high computational efficiency. Besides, the problem of \"spectrum splitting\", trouble for existing inner product-based method, may also be well avoided. Last, the effectiveness of the proposed method is demonstrated using detailed performance analysis based on numerical experiments.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127131839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435936
C. Qu, You He, F. Su, Yong Huang
Synthetic aperture radar (SAR) is an active, all-weather capable system to produce high resolution images of the ground. The two imaging directions are range and azimuth (flight direction). The relative motion between platform and ground is exploited for image generation in the azimuth. In SAR processing it is assumed that the ground is static. Moving targets cause errors in SAR images, like defocusing and displacement, depending on the direction of their motion. Since detection, identification and tracking of moving objects in SAR signals are necessary in both civil and military applications, the errors need to be corrected. In this paper, we propose the method based on the Chirp-Fourier transform (CFT) to detect moving targets. Processing steps of this method and simulated results are given in detail. Simulation results show this method can detect moving targets and estimate its parameters in noise case effectively.
{"title":"SAR moving targets detection based on the Chirp-Fourier transform","authors":"C. Qu, You He, F. Su, Yong Huang","doi":"10.1109/RADAR.2005.1435936","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435936","url":null,"abstract":"Synthetic aperture radar (SAR) is an active, all-weather capable system to produce high resolution images of the ground. The two imaging directions are range and azimuth (flight direction). The relative motion between platform and ground is exploited for image generation in the azimuth. In SAR processing it is assumed that the ground is static. Moving targets cause errors in SAR images, like defocusing and displacement, depending on the direction of their motion. Since detection, identification and tracking of moving objects in SAR signals are necessary in both civil and military applications, the errors need to be corrected. In this paper, we propose the method based on the Chirp-Fourier transform (CFT) to detect moving targets. Processing steps of this method and simulated results are given in detail. Simulation results show this method can detect moving targets and estimate its parameters in noise case effectively.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129976581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435955
H. A. Khan, W. Malik, D. Edwards, C. Stevens
The utilization of ultra wideband (UWB) signals enables the radar designer to solve the most important problems of radar target observation. The extremely wide bandwidth enables greater information to be obtained due to high time resolution and the frequency dependence of the scattering centers over this large bandwidth. Increase in the radar's signal bandwidth can improve radar performance by providing better range measurement accuracy, improving the target identification and tracking capability, improving radar immunity to passive interference, and enhancing radar countermeasure against narrowband electromagnetic signal interference. Recently there have been many advances in multiple-input multiple-output (MIMO) antenna systems in communications. These diversity systems have been shown to have the potential to dramatically improve the performance of the communications systems. Unlike the traditional beamforming approach, which uses highly correlated signals of an array of transmitting or receiving antenna elements to collimate a beam towards a certain direction in space, MIMO capitalizes on the independence between signals from different transmitters and on the diversity of target scattering to improve the information received from the response, Motivated by the advances and benefits of MIMO in communications and advantages of using UWB signals, this paper presents the experimental investigation of UWB-MIMO radars. The analysis of such radars has been carried out to demonstrate its promising features in terms of better target identification and improved signal to noise ratio (SNR).
{"title":"Ultra wideband multiple-input multiple-output radar","authors":"H. A. Khan, W. Malik, D. Edwards, C. Stevens","doi":"10.1109/RADAR.2005.1435955","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435955","url":null,"abstract":"The utilization of ultra wideband (UWB) signals enables the radar designer to solve the most important problems of radar target observation. The extremely wide bandwidth enables greater information to be obtained due to high time resolution and the frequency dependence of the scattering centers over this large bandwidth. Increase in the radar's signal bandwidth can improve radar performance by providing better range measurement accuracy, improving the target identification and tracking capability, improving radar immunity to passive interference, and enhancing radar countermeasure against narrowband electromagnetic signal interference. Recently there have been many advances in multiple-input multiple-output (MIMO) antenna systems in communications. These diversity systems have been shown to have the potential to dramatically improve the performance of the communications systems. Unlike the traditional beamforming approach, which uses highly correlated signals of an array of transmitting or receiving antenna elements to collimate a beam towards a certain direction in space, MIMO capitalizes on the independence between signals from different transmitters and on the diversity of target scattering to improve the information received from the response, Motivated by the advances and benefits of MIMO in communications and advantages of using UWB signals, this paper presents the experimental investigation of UWB-MIMO radars. The analysis of such radars has been carried out to demonstrate its promising features in terms of better target identification and improved signal to noise ratio (SNR).","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131082634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435819
K. Morrison
The use of a frequency-agile waveform is proposed as a way of providing significantly increased bandwidth for a stepped frequency continuous wave (SF-CW) SAR, than is provided by traditional imaging schemes. The range resolution is set by the bandwidth of the transmitted waveform, and is built up as a set of monotonically increasing stepped frequencies. As these frequencies are sampled sequentially, a constraint with SF-CW waveforms is the time restriction available to build up the bandwidth, imposed by the spatial sampling requirements along the aperture to avoid grating-lobe effects. To address this problem, an approach is outlined which allows the frequency spectrum to be greatly under-sampled to provide a greater effective bandwidth. It was found that randomizing the set of frequencies omitted from sweep to sweep allowed significant thinning before the appearance of significant unwanted image artifacts due to the under-sampling. This scheme allows great flexibility in the choice of bandwidths that can be realized for a particular imaging scenario. Their application is considered from the point of view of operation from UAV SAR platforms.
{"title":"Increasing the effective bandwidth of an SF-CW SAR using frequency agility","authors":"K. Morrison","doi":"10.1109/RADAR.2005.1435819","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435819","url":null,"abstract":"The use of a frequency-agile waveform is proposed as a way of providing significantly increased bandwidth for a stepped frequency continuous wave (SF-CW) SAR, than is provided by traditional imaging schemes. The range resolution is set by the bandwidth of the transmitted waveform, and is built up as a set of monotonically increasing stepped frequencies. As these frequencies are sampled sequentially, a constraint with SF-CW waveforms is the time restriction available to build up the bandwidth, imposed by the spatial sampling requirements along the aperture to avoid grating-lobe effects. To address this problem, an approach is outlined which allows the frequency spectrum to be greatly under-sampled to provide a greater effective bandwidth. It was found that randomizing the set of frequencies omitted from sweep to sweep allowed significant thinning before the appearance of significant unwanted image artifacts due to the under-sampling. This scheme allows great flexibility in the choice of bandwidths that can be realized for a particular imaging scenario. Their application is considered from the point of view of operation from UAV SAR platforms.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127881071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435902
Y. Abramovich, N. Spencer
We demonstrate that by adopting the new class of "expected-likelihood" (EL) covariance matrix estimates, instead of the traditional maximum-likelihood (ML) estimates, we can significantly enhance adaptive detection performance. These new estimates are found by searching within the properly parameterized class of admissible covariance matrices for the one that produces the likelihood ratio (LR) that is "closest possible" to the LR generated by the true (exact) covariance matrix.
{"title":"Expected-likelihood covariance matrix estimation for adaptive detection","authors":"Y. Abramovich, N. Spencer","doi":"10.1109/RADAR.2005.1435902","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435902","url":null,"abstract":"We demonstrate that by adopting the new class of \"expected-likelihood\" (EL) covariance matrix estimates, instead of the traditional maximum-likelihood (ML) estimates, we can significantly enhance adaptive detection performance. These new estimates are found by searching within the properly parameterized class of admissible covariance matrices for the one that produces the likelihood ratio (LR) that is \"closest possible\" to the LR generated by the true (exact) covariance matrix.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129220343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435814
H. Borrion, H. Griffiths, P. Tait, D. Money, C. Baker
In this paper, we consider the estimation of scattering centre parameters for the case of extended targets. In general, models are tested on synthetic targets made up of few scatterers. This choice is imposed by the maximum model-order assumed by the method. It is limited by the rank of the observation matrix and by the noise which corrupts the signal subspace. However real-world systems have to deal with complex targets such as aircrafts. For this reason, we revisit the theory for the case of targets made up of a large number of scatterers. We present a novel method for selecting poles corresponding to true physical scatterers. Finally, we propose a technique for reducing the model order based on a modification to the ISAR technique. The resulting 2D-model results in lower noise compared to traditional techniques and can be used for pole selection, data compression, image enhancement and high resolution ISAR-imaging.
{"title":"Scattering centre extraction for extended targets","authors":"H. Borrion, H. Griffiths, P. Tait, D. Money, C. Baker","doi":"10.1109/RADAR.2005.1435814","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435814","url":null,"abstract":"In this paper, we consider the estimation of scattering centre parameters for the case of extended targets. In general, models are tested on synthetic targets made up of few scatterers. This choice is imposed by the maximum model-order assumed by the method. It is limited by the rank of the observation matrix and by the noise which corrupts the signal subspace. However real-world systems have to deal with complex targets such as aircrafts. For this reason, we revisit the theory for the case of targets made up of a large number of scatterers. We present a novel method for selecting poles corresponding to true physical scatterers. Finally, we propose a technique for reducing the model order based on a modification to the ISAR technique. The resulting 2D-model results in lower noise compared to traditional techniques and can be used for pole selection, data compression, image enhancement and high resolution ISAR-imaging.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123309191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435844
H. Griffiths, C. Baker
Passive coherent location (PCL) radar systems make use of broadcast or communications 'illuminators of opportunity' in a bistatic configuration. In order to understand the performance limitations of this type of radar it is necessary to know the ambiguity properties of these waveforms, and how they vary with the form of modulation and with the bistatic geometry. This paper presents and analyses the ambiguity functions of a set of off-air measurements of signals that might be used for PCL systems. We find that the ambiguity behavior of analog modulation formats, such as FM radio or analog television, depend significantly on the instantaneous program content, and can be very poor, for example during pauses in speech. Digital modulation formats, in contrast, are much more favorable and much more constant with time. This suggests that the choice of signals to be used for PCL may be made on a dynamic basis, according to the modulation and bistatic geometry.
{"title":"Measurement and analysis of ambiguity functions of passive radar transmissions","authors":"H. Griffiths, C. Baker","doi":"10.1109/RADAR.2005.1435844","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435844","url":null,"abstract":"Passive coherent location (PCL) radar systems make use of broadcast or communications 'illuminators of opportunity' in a bistatic configuration. In order to understand the performance limitations of this type of radar it is necessary to know the ambiguity properties of these waveforms, and how they vary with the form of modulation and with the bistatic geometry. This paper presents and analyses the ambiguity functions of a set of off-air measurements of signals that might be used for PCL systems. We find that the ambiguity behavior of analog modulation formats, such as FM radio or analog television, depend significantly on the instantaneous program content, and can be very poor, for example during pauses in speech. Digital modulation formats, in contrast, are much more favorable and much more constant with time. This suggests that the choice of signals to be used for PCL may be made on a dynamic basis, according to the modulation and bistatic geometry.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115278200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435858
M. Picciolo, G. N. Schoenig, L. Mili, K. Gerlach
This paper describes an adaptive radar method that significantly improves the signal to interference-plus-noise ratio (SINR) convergence performance of a block-processed cascaded canceller that uses a generic robust adaptive algorithm in its multiple building blocks. It is shown empirically that implementing a simple reiterative processing technique, whereby the canceller output channels are directed back to its own input channels multiple times, produces a subsequent overall adaptive convergence rate that is approximately independent of the effective rank of the input sample covariance matrix. It is noted that cascaded cancellers lend themselves to practical real-time implementation as systolic processors due to their highly parallel / pipelined signal flow structure. However, it is shown that reiterative processing provides the desired SMI-like convergence independence feature when used in conjunction with generic (i.e., nonGSCC) robust adaptive cascaded cancellers; without reiterative processing this feature is generally lost. Thus, by using reiterative processing, generic cascaded canceller building block algorithms may be made robust to realistic data without concern for placing an unintentional, rank-dependent, convergence limitation on the processor. Results for several disparate robust adaptive algorithms support this conclusion.
{"title":"Rank-independent convergence for generic robust adaptive cascaded cancellers via reiterative processing","authors":"M. Picciolo, G. N. Schoenig, L. Mili, K. Gerlach","doi":"10.1109/RADAR.2005.1435858","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435858","url":null,"abstract":"This paper describes an adaptive radar method that significantly improves the signal to interference-plus-noise ratio (SINR) convergence performance of a block-processed cascaded canceller that uses a generic robust adaptive algorithm in its multiple building blocks. It is shown empirically that implementing a simple reiterative processing technique, whereby the canceller output channels are directed back to its own input channels multiple times, produces a subsequent overall adaptive convergence rate that is approximately independent of the effective rank of the input sample covariance matrix. It is noted that cascaded cancellers lend themselves to practical real-time implementation as systolic processors due to their highly parallel / pipelined signal flow structure. However, it is shown that reiterative processing provides the desired SMI-like convergence independence feature when used in conjunction with generic (i.e., nonGSCC) robust adaptive cascaded cancellers; without reiterative processing this feature is generally lost. Thus, by using reiterative processing, generic cascaded canceller building block algorithms may be made robust to realistic data without concern for placing an unintentional, rank-dependent, convergence limitation on the processor. Results for several disparate robust adaptive algorithms support this conclusion.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116717016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-09DOI: 10.1109/RADAR.2005.1435878
Wang Min, Yu Shuyuan
In this paper, a new edge detection method for SAR image using a hybrid genetic algorithm (HGA) is proposed depending on a full study about the characteristics of SAR images. According to this method, firstly some new types of edges are defined, and then the edge detection is reduced to an optimization problem. Not only original image data, but also some local information of edge, such as the continuity, thickness and regional difference of edges are included to define a cost function. Therefore, by the global searching capability of genetic algorithm, more continuous and accurate edges can be detected than other traditional methods. Moreover, a local optimization operator is employed to speed up the convergence of algorithm. So the method presents a remarkably rapider speed than classical genetic algorithm, as well as better edges. The simulations results also demonstrate its efficiency.
{"title":"A hybrid genetic algorithm-based edge detection method for SAR image","authors":"Wang Min, Yu Shuyuan","doi":"10.1109/RADAR.2005.1435878","DOIUrl":"https://doi.org/10.1109/RADAR.2005.1435878","url":null,"abstract":"In this paper, a new edge detection method for SAR image using a hybrid genetic algorithm (HGA) is proposed depending on a full study about the characteristics of SAR images. According to this method, firstly some new types of edges are defined, and then the edge detection is reduced to an optimization problem. Not only original image data, but also some local information of edge, such as the continuity, thickness and regional difference of edges are included to define a cost function. Therefore, by the global searching capability of genetic algorithm, more continuous and accurate edges can be detected than other traditional methods. Moreover, a local optimization operator is employed to speed up the convergence of algorithm. So the method presents a remarkably rapider speed than classical genetic algorithm, as well as better edges. The simulations results also demonstrate its efficiency.","PeriodicalId":444253,"journal":{"name":"IEEE International Radar Conference, 2005.","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123797410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：