- Yu Chen;Zihao Wang;Lun Li;Jingrong Zhang;Xiaohua Wan;Fei Sun;Fa Zhang;
Electron Tomography(ET) is an important method for studying cell ultrastructure in three-dimensional(3 D) space. By combining cryo-electron tomography of frozen-hydrated samples(cryo-ET) and a sub-tomogram averaging approach, ET has recently reached sub-nanometer resolution, thereby realizing the capability for gaining direct insights into function and mechanism. To obtain a high-resolution 3 D ET reconstruction, alignment and geometry determination of the ET tilt series are necessary. However, typical methods for determining geometry require human intervention, which is not only subjective and easily introduces errors, but is also labor intensive for high-throughput tomographic reconstructions. To overcome these problems, we have developed an automatic geometry-determination method, called Auto GDeterm. By taking advantage of the high-contrast re-projections of the Iterative Compressed-sensing Optimized Non-Uniform Fast Fourier Transform(NUFFT) reconstruction(ICON)and a series of numerical analysis methods, Auto GDeterm achieves high-precision fully automated geometry determination. Experimental results on simulated and resin-embedded datasets show that the accuracy of Auto GDeterm is high and comparable to that of the typical "manual positioning" method. We have made Auto GDeterm available as software, which can be freely downloaded from our website http://ear.ict.ac.cn.
2018年04期 v.23 369-376页 [查看摘要][在线阅读][下载 811K] [下载次数：24 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - Yu Chen;Zihao Wang;Lun Li;Jingrong Zhang;Xiaohua Wan;Fei Sun;Fa Zhang;
Electron Tomography(ET) is an important method for studying cell ultrastructure in three-dimensional(3 D) space. By combining cryo-electron tomography of frozen-hydrated samples(cryo-ET) and a sub-tomogram averaging approach, ET has recently reached sub-nanometer resolution, thereby realizing the capability for gaining direct insights into function and mechanism. To obtain a high-resolution 3 D ET reconstruction, alignment and geometry determination of the ET tilt series are necessary. However, typical methods for determining geometry require human intervention, which is not only subjective and easily introduces errors, but is also labor intensive for high-throughput tomographic reconstructions. To overcome these problems, we have developed an automatic geometry-determination method, called Auto GDeterm. By taking advantage of the high-contrast re-projections of the Iterative Compressed-sensing Optimized Non-Uniform Fast Fourier Transform(NUFFT) reconstruction(ICON)and a series of numerical analysis methods, Auto GDeterm achieves high-precision fully automated geometry determination. Experimental results on simulated and resin-embedded datasets show that the accuracy of Auto GDeterm is high and comparable to that of the typical "manual positioning" method. We have made Auto GDeterm available as software, which can be freely downloaded from our website http://ear.ict.ac.cn.
2018年04期 v.23 369-376页 [查看摘要][在线阅读][下载 811K] [下载次数：24 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - Baohua Huang;Xiaolu Cheng;Caixia Huang;Wei Cheng;
Keeping Vehicular Ad hoc Network(VANET) from attacks requires secure and efficient distribution of information about bad entities. Negative messages are pieces of information that define the negative attributes of vehicles. By formally defining the negative message, we observe that accuracy is essential for its efficient distribution. We formally define the coverage percentage and accurate coverage percentage to describe the availability and distribution efficiency of negative message. These two metrics can jointly evaluate the performance of a distribution method. To obtain both high coverage percentage and high accurate coverage percentage, we propose meet-cloud, a scheme based on meet-table and cloud computing to securely and accurately distribute negative messages in VANET. A meet-table in a Road Side Unit(RSU) records the vehicles it encounters. All meettables are sent to cloud service to aggregate a global meet-table. The algorithm for distributing and redistributing negative messages are designed. Security analysis shows that meet-cloud is secure against fake and holding on to negative message attacks. Simulations and analysis demonstrate that meet-cloud is secure under denial of service and fake meet-table attacks. The simulation results also justify that meet-cloud outperforms the RSU broadcast and epidemic model.
2018年04期 v.23 377-388页 [查看摘要][在线阅读][下载 1344K] [下载次数：43 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Baohua Huang;Xiaolu Cheng;Caixia Huang;Wei Cheng;
Keeping Vehicular Ad hoc Network(VANET) from attacks requires secure and efficient distribution of information about bad entities. Negative messages are pieces of information that define the negative attributes of vehicles. By formally defining the negative message, we observe that accuracy is essential for its efficient distribution. We formally define the coverage percentage and accurate coverage percentage to describe the availability and distribution efficiency of negative message. These two metrics can jointly evaluate the performance of a distribution method. To obtain both high coverage percentage and high accurate coverage percentage, we propose meet-cloud, a scheme based on meet-table and cloud computing to securely and accurately distribute negative messages in VANET. A meet-table in a Road Side Unit(RSU) records the vehicles it encounters. All meettables are sent to cloud service to aggregate a global meet-table. The algorithm for distributing and redistributing negative messages are designed. Security analysis shows that meet-cloud is secure against fake and holding on to negative message attacks. Simulations and analysis demonstrate that meet-cloud is secure under denial of service and fake meet-table attacks. The simulation results also justify that meet-cloud outperforms the RSU broadcast and epidemic model.
2018年04期 v.23 377-388页 [查看摘要][在线阅读][下载 1344K] [下载次数：43 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Zaobo He;Yingshu Li;Ji Li;Kaiyang Li;Qing Cai;Yi Liang;
Privacy preserving data releasing is an important problem for reconciling data openness with individual privacy. The state-of-the-art approach for privacy preserving data release is differential privacy, which offers powerful privacy guarantee without confining assumptions about the background knowledge about attackers. For genomic data with huge-dimensional attributes, however, current approaches based on differential privacy are not effective to handle. Specifically, amount of noise is required to be injected to genomic data with tens of million of SNPs(Single Nucleotide Polymorphisms), which would significantly degrade the utility of released data. To address this problem, this paper proposes a differential privacy guaranteed genomic data releasing method. Through executing belief propagation on factor graph, our method can factorize the distribution of sensitive genomic data into a set of local distributions. After injecting differential-privacy noise to these local distributions, synthetic sensitive data can be obtained by sampling on noise distribution. Synthetic sensitive data and factor graph can be further used to construct approximate distribution of non-sensitive data. Finally, non-sensitive genomic data is sampled from the approximate distribution to construct a synthetic genomic dataset.
2018年04期 v.23 389-395页 [查看摘要][在线阅读][下载 273K] [下载次数：36 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Zaobo He;Yingshu Li;Ji Li;Kaiyang Li;Qing Cai;Yi Liang;
Privacy preserving data releasing is an important problem for reconciling data openness with individual privacy. The state-of-the-art approach for privacy preserving data release is differential privacy, which offers powerful privacy guarantee without confining assumptions about the background knowledge about attackers. For genomic data with huge-dimensional attributes, however, current approaches based on differential privacy are not effective to handle. Specifically, amount of noise is required to be injected to genomic data with tens of million of SNPs(Single Nucleotide Polymorphisms), which would significantly degrade the utility of released data. To address this problem, this paper proposes a differential privacy guaranteed genomic data releasing method. Through executing belief propagation on factor graph, our method can factorize the distribution of sensitive genomic data into a set of local distributions. After injecting differential-privacy noise to these local distributions, synthetic sensitive data can be obtained by sampling on noise distribution. Synthetic sensitive data and factor graph can be further used to construct approximate distribution of non-sensitive data. Finally, non-sensitive genomic data is sampled from the approximate distribution to construct a synthetic genomic dataset.
2018年04期 v.23 389-395页 [查看摘要][在线阅读][下载 273K] [下载次数：36 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Ling Tian;Jiaxin Li;Yimin Zhou;Hongyu Wang;
The growing popularity of Internet applications and services has rendered high subjective video quality crucial to the user experience. Increasing needs for better video resolution and faster transmission bandwidths present challenges to the goal of achieving balance between video quality and coding cost. In this paper, we propose a Perceptive Variable Bit-Rate Control(PVBRC) framework for the state-of-the-art video coding standard High-Efficiency Video Coding(HEVC)/H.265. PVBRC allocates a bit-rate to a picture while taking a Comprehensive Picture Quality Assessment(CPQA) model and perceptive target bit-rate allocation into consideration. The CPQA model calculates the objective and perceptive quality of both source and reconstructed pictures by referring to the human vision system. The coding bit-rate is then dynamically allocated by the result of the CPQA model according to differences in picture content. In PVBRC, the quantization parameter for current picture encoding is updated by an effective fuzzy logical controller to satisfy the transmission requirements of the Internet of Things. Experimental results show that the proposed PVBRC can achieve average bit savings by 11.49% when compared with constant bit-rate control under the same objective and subjective video quality.
2018年04期 v.23 396-405页 [查看摘要][在线阅读][下载 856K] [下载次数：18 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Ling Tian;Jiaxin Li;Yimin Zhou;Hongyu Wang;
The growing popularity of Internet applications and services has rendered high subjective video quality crucial to the user experience. Increasing needs for better video resolution and faster transmission bandwidths present challenges to the goal of achieving balance between video quality and coding cost. In this paper, we propose a Perceptive Variable Bit-Rate Control(PVBRC) framework for the state-of-the-art video coding standard High-Efficiency Video Coding(HEVC)/H.265. PVBRC allocates a bit-rate to a picture while taking a Comprehensive Picture Quality Assessment(CPQA) model and perceptive target bit-rate allocation into consideration. The CPQA model calculates the objective and perceptive quality of both source and reconstructed pictures by referring to the human vision system. The coding bit-rate is then dynamically allocated by the result of the CPQA model according to differences in picture content. In PVBRC, the quantization parameter for current picture encoding is updated by an effective fuzzy logical controller to satisfy the transmission requirements of the Internet of Things. Experimental results show that the proposed PVBRC can achieve average bit savings by 11.49% when compared with constant bit-rate control under the same objective and subjective video quality.
2018年04期 v.23 396-405页 [查看摘要][在线阅读][下载 856K] [下载次数：18 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Yang Zhang;Hong Gao;Siyao Cheng;Jianzhong Li;
An Energy-Harvesting Wireless Sensor Network(EH-WSN) depends on harvesting energy from the environment to prolong network lifetime. Subjected to limited energy in complex environments, an EH-WSN encounters difficulty when applied to real environments as the network efficiency is reduced. Existing EH-WSN studies are usually conducted in assumed conditions in which nodes are synchronized and the energy profile is knowable or calculable. In real environments, nodes may lose their synchronization due to lack of energy.Furthermore, energy harvesting is significantly affected by multiple factors, whereas the ideal hypothesis is difficult to achieve in reality. In this paper, we introduce a general Intermittent Energy-Aware(IEA) EH-WSN platform.For the first time, we adopted a double-stage capacitor structure to ensure node synchronization in situations without energy harvesting, and we used an integrator to achieve ultra-low power measurement. With regard to hardware and software, we provided an optimized energy management mechanism for intermittent functioning.This paper describes the overall design of the IEA platform, and elaborates the energy management mechanism from the aspects of energy management, energy measurement, and energy prediction. In addition, we achieved node synchronization in different time and energy environments, measured the energy in reality, and proposed the light weight energy calculation method based on measured solar energy. In real environments, experiments are performed to verify the high performance of IEA in terms of validity and reliability. The IEA platform is shown to have ultra-low power consumption and high accuracy for energy measurement and prediction.
2018年04期 v.23 406-418页 [查看摘要][在线阅读][下载 878K] [下载次数：71 ] |[网刊下载次数：0 ] |[引用频次：27 ] |[阅读次数：0 ] - Yang Zhang;Hong Gao;Siyao Cheng;Jianzhong Li;
An Energy-Harvesting Wireless Sensor Network(EH-WSN) depends on harvesting energy from the environment to prolong network lifetime. Subjected to limited energy in complex environments, an EH-WSN encounters difficulty when applied to real environments as the network efficiency is reduced. Existing EH-WSN studies are usually conducted in assumed conditions in which nodes are synchronized and the energy profile is knowable or calculable. In real environments, nodes may lose their synchronization due to lack of energy.Furthermore, energy harvesting is significantly affected by multiple factors, whereas the ideal hypothesis is difficult to achieve in reality. In this paper, we introduce a general Intermittent Energy-Aware(IEA) EH-WSN platform.For the first time, we adopted a double-stage capacitor structure to ensure node synchronization in situations without energy harvesting, and we used an integrator to achieve ultra-low power measurement. With regard to hardware and software, we provided an optimized energy management mechanism for intermittent functioning.This paper describes the overall design of the IEA platform, and elaborates the energy management mechanism from the aspects of energy management, energy measurement, and energy prediction. In addition, we achieved node synchronization in different time and energy environments, measured the energy in reality, and proposed the light weight energy calculation method based on measured solar energy. In real environments, experiments are performed to verify the high performance of IEA in terms of validity and reliability. The IEA platform is shown to have ultra-low power consumption and high accuracy for energy measurement and prediction.
2018年04期 v.23 406-418页 [查看摘要][在线阅读][下载 878K] [下载次数：71 ] |[网刊下载次数：0 ] |[引用频次：27 ] |[阅读次数：0 ] - Fan Wu;Wang Yang;Runtong Chen;Xinfang Xie;
With the increasing utilization of High-Speed Trains(HSTs), the need for a reliable and high-bandwidth Internet access under high-speed mobility scenarios has become more demanding. In static, walking, and low mobility environments, TCP/IP(transmission control protocol/Internet protocol) can work well. However, TCP/IP cannot work well in high-speed scenarios because of reliability and handoff delay problems. This is mainly because the mobile node is required to maintain the connection to the corresponding node when it handovers to another access point node. In this paper, we propose a named data networking wireless mesh network architecture for HST wireless communication(NDN-Mesh-T), which combines the advantages of Wireless Mesh Networks(WMNs) and NDN architectures. We attempt to solve the reliability and handoff delay problems to enable high bandwidth and low latency in Internet access in HST scenarios. To further improve reliability and bandwidth utilization, we propose a Direction-Aware Forwarding(DAF) strategy to forward Interest packet along the direction of the running train.The simulation results show that the proposed scheme can significantly reduce the packet loss rate by up to 51%compared to TCP/IP network architecture. Moreover, the proposed mechanism can reduce the network load,handoff delay, and data redundancy.
2018年04期 v.23 419-430页 [查看摘要][在线阅读][下载 1006K] [下载次数：46 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - Fan Wu;Wang Yang;Runtong Chen;Xinfang Xie;
With the increasing utilization of High-Speed Trains(HSTs), the need for a reliable and high-bandwidth Internet access under high-speed mobility scenarios has become more demanding. In static, walking, and low mobility environments, TCP/IP(transmission control protocol/Internet protocol) can work well. However, TCP/IP cannot work well in high-speed scenarios because of reliability and handoff delay problems. This is mainly because the mobile node is required to maintain the connection to the corresponding node when it handovers to another access point node. In this paper, we propose a named data networking wireless mesh network architecture for HST wireless communication(NDN-Mesh-T), which combines the advantages of Wireless Mesh Networks(WMNs) and NDN architectures. We attempt to solve the reliability and handoff delay problems to enable high bandwidth and low latency in Internet access in HST scenarios. To further improve reliability and bandwidth utilization, we propose a Direction-Aware Forwarding(DAF) strategy to forward Interest packet along the direction of the running train.The simulation results show that the proposed scheme can significantly reduce the packet loss rate by up to 51%compared to TCP/IP network architecture. Moreover, the proposed mechanism can reduce the network load,handoff delay, and data redundancy.
2018年04期 v.23 419-430页 [查看摘要][在线阅读][下载 1006K] [下载次数：46 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - Di Liu;Chuanhe Huang;Xi Chen;Xiaohua Jia;
In Future Space-Terrestrial Integrated Networks(FSTINs), mobility is the norm rather than the exception,the current TCP/IP architecture is not competent. As a promising future network architecture, Named Data Networking(NDN) can support content consumer mobility naturally, but the content producer mobility support remains a challenging problem. Most previous research simply considered this problem in terrestrial scenarios, which involve stable infrastructures to achieve node mobility management. In this paper, we consider the problem in an FSTIN scenario without special handover management infrastructures. Specifically, we propose a tracing-based producer mobility management scheme and an addressing-assisted forwarding method via NDN architecture. We formally describe Multi-Layered Satellite Networks via a Time Varying Graph model and define the foremost path calculating problem to calculate the route of space segment, as well as an algorithm that can function in both dense(connected)and sparse(delay/disruption tolerant) scenarios. Finally, we discuss the acceleration method that can improve the Space-Terrestrial Integrated forwarding efficiency. Performance evaluation demonstrates that the proposed scheme can support fast handover and efficient forwarding in the FSTIN scenario.
2018年04期 v.23 431-439页 [查看摘要][在线阅读][下载 1205K] [下载次数：33 ] |[网刊下载次数：0 ] |[引用频次：6 ] |[阅读次数：0 ] - Di Liu;Chuanhe Huang;Xi Chen;Xiaohua Jia;
In Future Space-Terrestrial Integrated Networks(FSTINs), mobility is the norm rather than the exception,the current TCP/IP architecture is not competent. As a promising future network architecture, Named Data Networking(NDN) can support content consumer mobility naturally, but the content producer mobility support remains a challenging problem. Most previous research simply considered this problem in terrestrial scenarios, which involve stable infrastructures to achieve node mobility management. In this paper, we consider the problem in an FSTIN scenario without special handover management infrastructures. Specifically, we propose a tracing-based producer mobility management scheme and an addressing-assisted forwarding method via NDN architecture. We formally describe Multi-Layered Satellite Networks via a Time Varying Graph model and define the foremost path calculating problem to calculate the route of space segment, as well as an algorithm that can function in both dense(connected)and sparse(delay/disruption tolerant) scenarios. Finally, we discuss the acceleration method that can improve the Space-Terrestrial Integrated forwarding efficiency. Performance evaluation demonstrates that the proposed scheme can support fast handover and efficient forwarding in the FSTIN scenario.
2018年04期 v.23 431-439页 [查看摘要][在线阅读][下载 1205K] [下载次数：33 ] |[网刊下载次数：0 ] |[引用频次：6 ] |[阅读次数：0 ] - Gongming Zhao;Liusheng Huang;Ziqiang Li;Hongli Xu;
In recent years, Software-Defined Networks(SDNs) have become a promising technology to improve network utilization. However, limited flow table size and long deployment delays may result in low network performance in large-scale networks and a poor user experience. While a typical solution to this issue is routing aggregation(i.e., wildcard routing), the aggregation feasibility problem and reduced network performance may be encountered. To address this dilemma, we first design a novel wildcard routing scheme, called the Tag-based Rule Placement Scheme(TRPS). We then formulate a Hybrid Routing by Joint optimization of Per-flow routing and Tagbased routing(HR-JPT) problem, and prove its NP-hardness. An algorithm with a bounded approximation factor is designed for this problem, and the proposed methods are implemented on a Mininet platform. Extensive simulation results show that our methods are efficient for wildcard/hybrid routing. For example, our proposed tag-based wildcard rule placement scheme can reduce the number of required rules by about 65% on average compared with previous wildcard routing methods. Our proposed hybrid routing algorithm can increase network throughput by about 43% compared with existing hybrid routing solutions.
2018年04期 v.23 440-452页 [查看摘要][在线阅读][下载 904K] [下载次数：15 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Gongming Zhao;Liusheng Huang;Ziqiang Li;Hongli Xu;
In recent years, Software-Defined Networks(SDNs) have become a promising technology to improve network utilization. However, limited flow table size and long deployment delays may result in low network performance in large-scale networks and a poor user experience. While a typical solution to this issue is routing aggregation(i.e., wildcard routing), the aggregation feasibility problem and reduced network performance may be encountered. To address this dilemma, we first design a novel wildcard routing scheme, called the Tag-based Rule Placement Scheme(TRPS). We then formulate a Hybrid Routing by Joint optimization of Per-flow routing and Tagbased routing(HR-JPT) problem, and prove its NP-hardness. An algorithm with a bounded approximation factor is designed for this problem, and the proposed methods are implemented on a Mininet platform. Extensive simulation results show that our methods are efficient for wildcard/hybrid routing. For example, our proposed tag-based wildcard rule placement scheme can reduce the number of required rules by about 65% on average compared with previous wildcard routing methods. Our proposed hybrid routing algorithm can increase network throughput by about 43% compared with existing hybrid routing solutions.
2018年04期 v.23 440-452页 [查看摘要][在线阅读][下载 904K] [下载次数：15 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Dan Yin;Yiran Shen;
Graph clustering has a long-standing problem in that it is difficult to identify all the groups of vertices that are cohesively connected along their internal edges but only sparsely connected along their external edges. Apart from structural information in social networks, the quality of the location-information clustering has been improved by identifying clusters in the graph that are closely connected and spatially compact. However, in real-world scenarios,the location information of some users may be unavailable for privacy reasons, which renders existing solutions ineffective. In this paper, we investigate the clustering problem of privacy-preserving social networks, and propose an algorithm that uses a prediction-and-clustering approach. First, the location of each invisible user is predicted with a probability distribution. Then, each user is iteratively assigned to different clusters. The experimental results verify the effectiveness and efficiency of our method, and our proposed algorithm exhibits high scalability on large social networks.
2018年04期 v.23 453-462页 [查看摘要][在线阅读][下载 365K] [下载次数：50 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Dan Yin;Yiran Shen;
Graph clustering has a long-standing problem in that it is difficult to identify all the groups of vertices that are cohesively connected along their internal edges but only sparsely connected along their external edges. Apart from structural information in social networks, the quality of the location-information clustering has been improved by identifying clusters in the graph that are closely connected and spatially compact. However, in real-world scenarios,the location information of some users may be unavailable for privacy reasons, which renders existing solutions ineffective. In this paper, we investigate the clustering problem of privacy-preserving social networks, and propose an algorithm that uses a prediction-and-clustering approach. First, the location of each invisible user is predicted with a probability distribution. Then, each user is iteratively assigned to different clusters. The experimental results verify the effectiveness and efficiency of our method, and our proposed algorithm exhibits high scalability on large social networks.
2018年04期 v.23 453-462页 [查看摘要][在线阅读][下载 365K] [下载次数：50 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Xuefeng Yan;Xiangwen Feng;Chengbo Song;Xiaolin Hu;
Particle Filter(PF) is a data assimilation method to solve recursive state estimation problem which does not depend on the assumption of Gaussian noise, and is able to be applied for various systems even with non-linear and non-Gaussian noise. However, while applying PF in dynamic systems, PF undergoes particle degeneracy,sample impoverishment, and problems of high computational complexity. Rapidly developing sensing technologies are providing highly convenient availability of real-time big traffic data from the system under study like never before. Moreover, some sensors can even receive control commands to adjust their monitoring parameters. To address these problems, a bidirectional dynamic data-driven improvement framework for PF(B3 DPF) is proposed.The B3 DPF enhances feedback between the simulation model and the big traffic data collected by the sensors,which means the execution strategies(sensor data management, parameters used in the weight computation,resampling) of B3 DPF can be optimized based on the simulation results and the types and dimensions of traffic data injected into B3 DPF can be adjusted dynamically. The first experiment indicates that the B3 DPF overcomes particle degeneracy and sample impoverishment problems and accurately estimates the state at a faster speed than the normal PF. More importantly, the new method has higher accuracy for multidimensional random systems.In the rest of experiments, the proposed framework is applied to estimate the traffic state on a real road network and obtains satisfactory results. More experiments can be designed to validate the universal properties of B3 DPF.
2018年04期 v.23 463-478页 [查看摘要][在线阅读][下载 748K] [下载次数：21 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - Xuefeng Yan;Xiangwen Feng;Chengbo Song;Xiaolin Hu;
Particle Filter(PF) is a data assimilation method to solve recursive state estimation problem which does not depend on the assumption of Gaussian noise, and is able to be applied for various systems even with non-linear and non-Gaussian noise. However, while applying PF in dynamic systems, PF undergoes particle degeneracy,sample impoverishment, and problems of high computational complexity. Rapidly developing sensing technologies are providing highly convenient availability of real-time big traffic data from the system under study like never before. Moreover, some sensors can even receive control commands to adjust their monitoring parameters. To address these problems, a bidirectional dynamic data-driven improvement framework for PF(B3 DPF) is proposed.The B3 DPF enhances feedback between the simulation model and the big traffic data collected by the sensors,which means the execution strategies(sensor data management, parameters used in the weight computation,resampling) of B3 DPF can be optimized based on the simulation results and the types and dimensions of traffic data injected into B3 DPF can be adjusted dynamically. The first experiment indicates that the B3 DPF overcomes particle degeneracy and sample impoverishment problems and accurately estimates the state at a faster speed than the normal PF. More importantly, the new method has higher accuracy for multidimensional random systems.In the rest of experiments, the proposed framework is applied to estimate the traffic state on a real road network and obtains satisfactory results. More experiments can be designed to validate the universal properties of B3 DPF.
2018年04期 v.23 463-478页 [查看摘要][在线阅读][下载 748K] [下载次数：21 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - Lizong Zhang;Nawaf R Alharbe;Guangchun Luo;Zhiyuan Yao;Ying Li;
The ability to perform short-term traffic flow forecasting is a crucial component of intelligent transportation systems. However, accurate and reliable traffic flow forecasting is still a significant issue due to the complexity and variability of real traffic systems. To improve the accuracy of short-term traffic flow forecasting, this paper presents a novel hybrid prediction framework based on Support Vector Regression(SVR) that uses a Random Forest(RF) to select the most informative feature subset and an enhanced Genetic Algorithm(GA) with chaotic characteristics to identify the optimal forecasting model parameters. The framework is evaluated with real-world traffic data collected from eight sensors located near the I-605 interstate highway in California. Results show that the proposed RFCGASVR model achieves better performance than other methods.
2018年04期 v.23 479-492页 [查看摘要][在线阅读][下载 976K] [下载次数：227 ] |[网刊下载次数：0 ] |[引用频次：74 ] |[阅读次数：0 ] - Lizong Zhang;Nawaf R Alharbe;Guangchun Luo;Zhiyuan Yao;Ying Li;
The ability to perform short-term traffic flow forecasting is a crucial component of intelligent transportation systems. However, accurate and reliable traffic flow forecasting is still a significant issue due to the complexity and variability of real traffic systems. To improve the accuracy of short-term traffic flow forecasting, this paper presents a novel hybrid prediction framework based on Support Vector Regression(SVR) that uses a Random Forest(RF) to select the most informative feature subset and an enhanced Genetic Algorithm(GA) with chaotic characteristics to identify the optimal forecasting model parameters. The framework is evaluated with real-world traffic data collected from eight sensors located near the I-605 interstate highway in California. Results show that the proposed RFCGASVR model achieves better performance than other methods.
2018年04期 v.23 479-492页 [查看摘要][在线阅读][下载 976K] [下载次数：227 ] |[网刊下载次数：0 ] |[引用频次：74 ] |[阅读次数：0 ] - Wei Zhao;Lin Zhao;Weidong Wu;Sigen Chen;Shaohui Sun;Yong Cao;
A Relay-Assisted(RA) network with relay selection is considered as a type of effective technology to improve the spectrum and energy efficiency of a cellular network. However, loading balance of the assisted relay node becomes an inevitable bottleneck in RA network development because users do not follow uniform distribution. Furthermore, the time-varying channel condition of wireless communication is also a major challenge for the RA network with relay selection. To solve these problems and improve the practicability of the RA network, a Loading Balance-Relay Selective(LBRS) strategy is proposed for the RA network in this paper. The proposed LBRS strategy formulates the relay selection of the RA network under imperfect channel state information assumption as a Multistage Decision(MD) problem. An optimal algorithm is also investigated to solve the proposed MD problem based on stochastic dynamic program. Numerical results show that the performance of the LBRS strategy is better than that of traditional greedy algorithm and the former is effective as an exhaustive search-based method.
2018年04期 v.23 493-500页 [查看摘要][在线阅读][下载 452K] [下载次数：30 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - Wei Zhao;Lin Zhao;Weidong Wu;Sigen Chen;Shaohui Sun;Yong Cao;
A Relay-Assisted(RA) network with relay selection is considered as a type of effective technology to improve the spectrum and energy efficiency of a cellular network. However, loading balance of the assisted relay node becomes an inevitable bottleneck in RA network development because users do not follow uniform distribution. Furthermore, the time-varying channel condition of wireless communication is also a major challenge for the RA network with relay selection. To solve these problems and improve the practicability of the RA network, a Loading Balance-Relay Selective(LBRS) strategy is proposed for the RA network in this paper. The proposed LBRS strategy formulates the relay selection of the RA network under imperfect channel state information assumption as a Multistage Decision(MD) problem. An optimal algorithm is also investigated to solve the proposed MD problem based on stochastic dynamic program. Numerical results show that the performance of the LBRS strategy is better than that of traditional greedy algorithm and the former is effective as an exhaustive search-based method.
2018年04期 v.23 493-500页 [查看摘要][在线阅读][下载 452K] [下载次数：30 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - Jianjiang Li;Peng Wei;Shaofeng Yang;Jie Wu;Peng Liu;Xinfu He;
Kinetic Monte Carlo(KMC) is a widely used method for studying the evolution of materials at the microcosmic level. At present, while there are many simulation software programs based on this algorithm, most focus on the verification of a certain phenomenon and have no analog-scale requirement, so many are serial in nature. The dynamic Monte Carlo algorithm is implemented using a parallel framework called SPPARKS, but it does not support the Embedded Atom Method(EAM) potential, which is commonly used in the dynamic simulation of metal materials. Metal material — the preferred material for most containers and components — plays an important role in many fields, including construction engineering and transportation. In this paper, we propose and describe the development of a parallel software program called Crystal-KMC, which is specifically used to simulate the lattice dynamics of metallic materials. This software uses MPI to achieve a parallel multiprocessing mode, which avoid the limitations of serial software in the analog scale. Finally, we describe the use of the parallel-KMC simulation software Crystal-KMC in simulating the diffusion of vacancies in iron, and analyze the experimental results. In addition, we tested the performance of Crystal-KMC in "meta-Era" supercomputing clusters, and the results show the Crystal-KMC parallel software to have good parallel speedup and scalability.
2018年04期 v.23 501-510页 [查看摘要][在线阅读][下载 1138K] [下载次数：69 ] |[网刊下载次数：0 ] |[引用频次：7 ] |[阅读次数：0 ] - Jianjiang Li;Peng Wei;Shaofeng Yang;Jie Wu;Peng Liu;Xinfu He;
Kinetic Monte Carlo(KMC) is a widely used method for studying the evolution of materials at the microcosmic level. At present, while there are many simulation software programs based on this algorithm, most focus on the verification of a certain phenomenon and have no analog-scale requirement, so many are serial in nature. The dynamic Monte Carlo algorithm is implemented using a parallel framework called SPPARKS, but it does not support the Embedded Atom Method(EAM) potential, which is commonly used in the dynamic simulation of metal materials. Metal material — the preferred material for most containers and components — plays an important role in many fields, including construction engineering and transportation. In this paper, we propose and describe the development of a parallel software program called Crystal-KMC, which is specifically used to simulate the lattice dynamics of metallic materials. This software uses MPI to achieve a parallel multiprocessing mode, which avoid the limitations of serial software in the analog scale. Finally, we describe the use of the parallel-KMC simulation software Crystal-KMC in simulating the diffusion of vacancies in iron, and analyze the experimental results. In addition, we tested the performance of Crystal-KMC in "meta-Era" supercomputing clusters, and the results show the Crystal-KMC parallel software to have good parallel speedup and scalability.
2018年04期 v.23 501-510页 [查看摘要][在线阅读][下载 1138K] [下载次数：69 ] |[网刊下载次数：0 ] |[引用频次：7 ] |[阅读次数：0 ] -
<正>The publication of Tsinghua Science and Technology was started in 1996.Since then,it has been an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-the-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital
2018年04期 v.23 511页 [查看摘要][在线阅读][下载 40K] [下载次数：18 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] <正>The publication of Tsinghua Science and Technology was started in 1996.Since then,it has been an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-the-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital
2018年04期 v.23 511页 [查看摘要][在线阅读][下载 40K] [下载次数：18 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] -
<正>The publication of Tsinghua Science and Technology was started in 1996.Since then,it has been an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-the-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital
2018年04期 v.23 512页 [查看摘要][在线阅读][下载 40K] [下载次数：18 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] <正>The publication of Tsinghua Science and Technology was started in 1996.Since then,it has been an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-the-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital
2018年04期 v.23 512页 [查看摘要][在线阅读][下载 40K] [下载次数：18 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] -
<正>Tsinghua Science and Technology(Tsinghua Sci Technol),an academic journal sponsored by Tsinghua University,is published bimonthly.This journal aims at presenting the up-to-date scientific achievements with high creativity
2018年04期 v.23 513页 [查看摘要][在线阅读][下载 763K] [下载次数：9 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] <正>Tsinghua Science and Technology(Tsinghua Sci Technol),an academic journal sponsored by Tsinghua University,is published bimonthly.This journal aims at presenting the up-to-date scientific achievements with high creativity
2018年04期 v.23 513页 [查看摘要][在线阅读][下载 763K] [下载次数：9 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ]