Pub Date : 2011-06-26DOI: 10.1109/SPAWC.2011.5990468
F. Sun, E. de Carvalho
In this paper, we introduce an asymmetrical multi-way relay channel where a base station conveys independent symbols to K different users while receiving independent symbols from the users. In this network, user i Shas Mi antennas (i ∈ [1, …, K]), the base station has Σi=1K Mi antennas and the relay is equipped with NR antennas. To study the capacity of this network, the degree of freedom (DOF) is characterized to be 2 Σi=1K Mi if NR ≥ Σi=1K Mi. The DOF implies that the number of symbols any transmitter can deliver and receive is equivalent to its number of antennas. The DOF is achievable with a proposed joint multiple access and broadcast precoding design using the signal space alignment concept.
{"title":"Degrees of freedom of asymmetrical multi-way relay networks","authors":"F. Sun, E. de Carvalho","doi":"10.1109/SPAWC.2011.5990468","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990468","url":null,"abstract":"In this paper, we introduce an asymmetrical multi-way relay channel where a base station conveys independent symbols to K different users while receiving independent symbols from the users. In this network, user i Shas M<inf>i</inf> antennas (i ∈ [1, …, K]), the base station has Σ<inf>i=1</inf><sup>K</sup> M<inf>i</inf> antennas and the relay is equipped with N<inf>R</inf> antennas. To study the capacity of this network, the degree of freedom (DOF) is characterized to be 2 Σ<inf>i=1</inf><sup>K</sup> M<inf>i</inf> if N<inf>R</inf> ≥ Σ<inf>i=1</inf><sup>K</sup> M<inf>i</inf>. The DOF implies that the number of symbols any transmitter can deliver and receive is equivalent to its number of antennas. The DOF is achievable with a proposed joint multiple access and broadcast precoding design using the signal space alignment concept.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122664865","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990477
F. Harris, Xiaofei Chen, E. Venosa
In this paper we present an extremely efficient FFT based spectrum analyzer that performs constant-Q spectral analysis. Each stage of the proposed structure is formed of a half-band filter and a 2-to-1 down sampler. It shifts successive lower octaves to the same spectral interval; consequently, the same octave processor can be applied in all the stages. Fourier transforms are normally used for performing equally spaced, equal bandwidth spectral estimation; their main advantage is the efficiency of the FFT algorithm. In this paper, by post processing the output of the FFT block with a frequency sliding window having variable bandwidth, we are able to achieve spectral estimations at arbitrary center frequencies with arbitrary resolutions maintaining the advantages of using the FFT algorithm. To further decrease the total workload, a 4-path polyphase channelizer is used to down sample the octaves before processing them in the FFT block.
{"title":"An efficient FFT based spectrum analyzer for arbitrary center frequencies and arbitrary resolutions analysis","authors":"F. Harris, Xiaofei Chen, E. Venosa","doi":"10.1109/SPAWC.2011.5990477","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990477","url":null,"abstract":"In this paper we present an extremely efficient FFT based spectrum analyzer that performs constant-Q spectral analysis. Each stage of the proposed structure is formed of a half-band filter and a 2-to-1 down sampler. It shifts successive lower octaves to the same spectral interval; consequently, the same octave processor can be applied in all the stages. Fourier transforms are normally used for performing equally spaced, equal bandwidth spectral estimation; their main advantage is the efficiency of the FFT algorithm. In this paper, by post processing the output of the FFT block with a frequency sliding window having variable bandwidth, we are able to achieve spectral estimations at arbitrary center frequencies with arbitrary resolutions maintaining the advantages of using the FFT algorithm. To further decrease the total workload, a 4-path polyphase channelizer is used to down sample the octaves before processing them in the FFT block.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125019976","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990402
Yang Yang, Rick S. Blum
The broadcast-based consensus algorithm is one special type of randomized consensus algorithm, and is amenable to practical implementation in wireless networks. This paper focuses on the performance analysis of this broadcast-based consensus algorithm in the presence of non-zero-mean stochastic perturbations. It is demonstrated that as the algorithm proceeds, the deviation of the node states from their average will converge, in expectation, to a fixed value, which is determined by the Laplacian matrix of the network, the mixing parameter, and the mean of the stochastic perturbations. Asymptotic upper and lower bounds on the total mean-square deviation are derived, which describe the range of distances over which the node states deviate from consensus. These bounds can facilitate evaluation of the applicability of this algorithm in practice. In addition, performance of the broadcast-based consensus algorithm under zero-mean stochastic disturbances is also analyzed, and results regarding its convergence and mean-square deviation are given. The theoretical results presented in this work hold true regardless of the statistics of the stochastic disturbances, and are valid for arbitrary network topology as long as the topology is connected.
{"title":"On the performance of broadcast based consensus under non-zero-mean stochastic disturbances","authors":"Yang Yang, Rick S. Blum","doi":"10.1109/SPAWC.2011.5990402","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990402","url":null,"abstract":"The broadcast-based consensus algorithm is one special type of randomized consensus algorithm, and is amenable to practical implementation in wireless networks. This paper focuses on the performance analysis of this broadcast-based consensus algorithm in the presence of non-zero-mean stochastic perturbations. It is demonstrated that as the algorithm proceeds, the deviation of the node states from their average will converge, in expectation, to a fixed value, which is determined by the Laplacian matrix of the network, the mixing parameter, and the mean of the stochastic perturbations. Asymptotic upper and lower bounds on the total mean-square deviation are derived, which describe the range of distances over which the node states deviate from consensus. These bounds can facilitate evaluation of the applicability of this algorithm in practice. In addition, performance of the broadcast-based consensus algorithm under zero-mean stochastic disturbances is also analyzed, and results regarding its convergence and mean-square deviation are given. The theoretical results presented in this work hold true regardless of the statistics of the stochastic disturbances, and are valid for arbitrary network topology as long as the topology is connected.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"06 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127193844","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990425
Mustapha Amara, D. Slock, Y. Yuan-Wu
This paper proposes a novel closed form (CF) precoder design for multi-user multiple input multiple output broadcast channel (MU-MIMO BC). The proposed algorithm is based on Null Space Zero-Forcing or Null Space Zero-Forcing with Greedy Stream Selection. The idea is to construct the precoder in a recursive stream-wise manner. The design proceeds in two steps. The first step is a recursive selection of the best streams, under a zero-forcing (ZF) constraint. The selection is based on an extension of Gram-Schmidt orthogonalization for the MIMO channel case, involving SVDs (geared towards per stream DPC). The streams associated to the strongest singular values get selected. In a second step, the precoder for the selected streams are calculated according to one among several possible precoding techniques with eventually a power distribution optimization. The proposed algorithm is then compared to the best algorithms in the literature namely the ZFBF-SUS and to it's DPC version ZFDPC-SUS. The obtained results showed better performances closer to DPC.
{"title":"Near capacity linear closed form precoder design with recursive Stream Selection for MU-MIMO broadcast channels","authors":"Mustapha Amara, D. Slock, Y. Yuan-Wu","doi":"10.1109/SPAWC.2011.5990425","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990425","url":null,"abstract":"This paper proposes a novel closed form (CF) precoder design for multi-user multiple input multiple output broadcast channel (MU-MIMO BC). The proposed algorithm is based on Null Space Zero-Forcing or Null Space Zero-Forcing with Greedy Stream Selection. The idea is to construct the precoder in a recursive stream-wise manner. The design proceeds in two steps. The first step is a recursive selection of the best streams, under a zero-forcing (ZF) constraint. The selection is based on an extension of Gram-Schmidt orthogonalization for the MIMO channel case, involving SVDs (geared towards per stream DPC). The streams associated to the strongest singular values get selected. In a second step, the precoder for the selected streams are calculated according to one among several possible precoding techniques with eventually a power distribution optimization. The proposed algorithm is then compared to the best algorithms in the literature namely the ZFBF-SUS and to it's DPC version ZFDPC-SUS. The obtained results showed better performances closer to DPC.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130405677","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990451
B. Ozbek, D. Le Ruyet
In this paper, we improve the performance of cell-edge users by applying adaptive bit partitioning for intercell interference cancelation in cooperative downlink multicell systems. The strategy for partitioning quantization bits between serving and interfering base stations affects the performance of the cooperative networks which is quite sensitive to the quality of the channel state information. The existing transmission strategies are based on the maximization of average cell rate which results in a reduced rate for the users in the cell-edge regions. We propose an adaptive bit partitioning strategy to improve the rate of cell-edge users at the same average feedback link rate. We show the performance of the cell-edge users is significantly increased while keeping the same average cell rate.
{"title":"Adaptive bit partitioning strategy for cell-edge users in multi-antenna multicell networks","authors":"B. Ozbek, D. Le Ruyet","doi":"10.1109/SPAWC.2011.5990451","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990451","url":null,"abstract":"In this paper, we improve the performance of cell-edge users by applying adaptive bit partitioning for intercell interference cancelation in cooperative downlink multicell systems. The strategy for partitioning quantization bits between serving and interfering base stations affects the performance of the cooperative networks which is quite sensitive to the quality of the channel state information. The existing transmission strategies are based on the maximization of average cell rate which results in a reduced rate for the users in the cell-edge regions. We propose an adaptive bit partitioning strategy to improve the rate of cell-edge users at the same average feedback link rate. We show the performance of the cell-edge users is significantly increased while keeping the same average cell rate.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128135107","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990403
M. Zavlanos, Alejandro Ribeiro, George J. Pappas
Most coordinated tasks performed by teams of mobile robots, require reliable communications between the members of the team. Therefore, task accomplishment requires that robots navigate their environment with their collective movement restricted to formations that guarantee integrity of the communication network. Maintaining this communication capability induces physical constraints on trajectories but also requires determination of communication variables like routes and transmitted powers. In this paper, we address this problem using a distributed hybrid approach, where continuous motion controllers based on potential fields interact with discrete distributed optimization of the communication variables to result in a muti-robot network that ensures integrity of communications. Our definition of network integrity is defined as the ability of a network to support desired communication rates.
{"title":"Distributed control of mobility & routing in networks of robots","authors":"M. Zavlanos, Alejandro Ribeiro, George J. Pappas","doi":"10.1109/SPAWC.2011.5990403","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990403","url":null,"abstract":"Most coordinated tasks performed by teams of mobile robots, require reliable communications between the members of the team. Therefore, task accomplishment requires that robots navigate their environment with their collective movement restricted to formations that guarantee integrity of the communication network. Maintaining this communication capability induces physical constraints on trajectories but also requires determination of communication variables like routes and transmitted powers. In this paper, we address this problem using a distributed hybrid approach, where continuous motion controllers based on potential fields interact with discrete distributed optimization of the communication variables to result in a muti-robot network that ensures integrity of communications. Our definition of network integrity is defined as the ability of a network to support desired communication rates.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128191270","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990379
M. Beko
In this paper, the energy-based localization problem in wireless sensor networks is addressed. The maximum likelihood (ML) location estimation problem is a difficult optimization problem due to the non-convexity of the objective function, and an exact solution is difficult to obtain. An approximate solution to the ML problem is proposed, by relaxing the minimization problem into semidefinite programming form. Simulation results show that the proposed algorithm outperforms the existing solutions.
{"title":"On energy-based localization in wireless sensor networks","authors":"M. Beko","doi":"10.1109/SPAWC.2011.5990379","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990379","url":null,"abstract":"In this paper, the energy-based localization problem in wireless sensor networks is addressed. The maximum likelihood (ML) location estimation problem is a difficult optimization problem due to the non-convexity of the objective function, and an exact solution is difficult to obtain. An approximate solution to the ML problem is proposed, by relaxing the minimization problem into semidefinite programming form. Simulation results show that the proposed algorithm outperforms the existing solutions.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"310 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134311550","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990388
Pouyan Parvazi, M. Pesavento
In this paper, a novel direction-of-arrival (DOA) method for partly-calibrated arrays composed of multiple identical subarrays is proposed. The new approach enables us not only to estimate the DOAs in this type of arrays but also, to simultaneously, compute the steering vectors of all subarrays. Unlike other methods for partly-calibrated arrays, our proposed algorithm exploits the estimated calibration information and the structure of the steering vector to estimate the DOAs. Simulation results show that the proposed method exhibits superior estimation performance, both in threshold domain and asymptotically as compared to existing methods.
{"title":"A new direction-of-arrival estimation and calibration method for arrays composed of multiple identical subarrays","authors":"Pouyan Parvazi, M. Pesavento","doi":"10.1109/SPAWC.2011.5990388","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990388","url":null,"abstract":"In this paper, a novel direction-of-arrival (DOA) method for partly-calibrated arrays composed of multiple identical subarrays is proposed. The new approach enables us not only to estimate the DOAs in this type of arrays but also, to simultaneously, compute the steering vectors of all subarrays. Unlike other methods for partly-calibrated arrays, our proposed algorithm exploits the estimated calibration information and the structure of the steering vector to estimate the DOAs. Simulation results show that the proposed method exhibits superior estimation performance, both in threshold domain and asymptotically as compared to existing methods.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116897642","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990384
M. R. Gholami, H. Wymeersch, E. Strom, M. Rydstrom
The problem of positioning targets based on distance estimates is studied for cooperative wireless sensor networks when there is limited a priori information about measurements noise. To solve this problem, two different methods of positioning are considered: statistical and geometrical. Based on a geometric interpretation, we show that the positioning problem can be rendered as finding the intersection of a number of convex sets. To find this intersection, we propose two different methods based on projection onto convex sets and outer-approximation. In the statistical approach, a partly novel two-step linear estimator is proposed which can be expressed in a closed-form solution. We also propose a new constrained non-linear least squares algorithm based on constraints derived in the outer-approximation approach. Simulation results show that the geometrical methods are more robust against non-line-of-sight measurements than the statistical approaches while in dense networks with line-of-sight measurements statistical approaches outperform geometrical methods.
{"title":"Robust distributed positioning algorithms for cooperative networks","authors":"M. R. Gholami, H. Wymeersch, E. Strom, M. Rydstrom","doi":"10.1109/SPAWC.2011.5990384","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990384","url":null,"abstract":"The problem of positioning targets based on distance estimates is studied for cooperative wireless sensor networks when there is limited a priori information about measurements noise. To solve this problem, two different methods of positioning are considered: statistical and geometrical. Based on a geometric interpretation, we show that the positioning problem can be rendered as finding the intersection of a number of convex sets. To find this intersection, we propose two different methods based on projection onto convex sets and outer-approximation. In the statistical approach, a partly novel two-step linear estimator is proposed which can be expressed in a closed-form solution. We also propose a new constrained non-linear least squares algorithm based on constraints derived in the outer-approximation approach. Simulation results show that the geometrical methods are more robust against non-line-of-sight measurements than the statistical approaches while in dense networks with line-of-sight measurements statistical approaches outperform geometrical methods.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114432120","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 : 2011-06-26DOI: 10.1109/SPAWC.2011.5990381
Tsang-Yi Wang, Jwo-Yuh Wu
Energy consumption is a vital concern when implementing distributed decision fusion in most wireless sensor networks. This paper studies the impact of sensor censoring on the decision fusion performance when the number of sensors is unknown at the fusion center. The global decision rule adopted at the fusion center is the Chair-Varshney fusion rule modified to take account of the unknown network size. It is shown that under the assumption of equally likely hypotheses, allowing more transmitting sensors does not necessarily yield better decision fusion; rather, there exists a censoring probability threshold below which the increase in the number of active sensors just incurs more intra-network communication overhead but will not improve the global decision performance. Our findings establish that the design of energy-efficient local detection rules should commence with the censoring rate threshold.
{"title":"Further results on decision fusion in censoring sensor networks: An unknown network size","authors":"Tsang-Yi Wang, Jwo-Yuh Wu","doi":"10.1109/SPAWC.2011.5990381","DOIUrl":"https://doi.org/10.1109/SPAWC.2011.5990381","url":null,"abstract":"Energy consumption is a vital concern when implementing distributed decision fusion in most wireless sensor networks. This paper studies the impact of sensor censoring on the decision fusion performance when the number of sensors is unknown at the fusion center. The global decision rule adopted at the fusion center is the Chair-Varshney fusion rule modified to take account of the unknown network size. It is shown that under the assumption of equally likely hypotheses, allowing more transmitting sensors does not necessarily yield better decision fusion; rather, there exists a censoring probability threshold below which the increase in the number of active sensors just incurs more intra-network communication overhead but will not improve the global decision performance. Our findings establish that the design of energy-efficient local detection rules should commence with the censoring rate threshold.","PeriodicalId":102244,"journal":{"name":"2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125246939","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：