电网中特大功率负荷的功率动态变化对智能电能表产生不同程度的影响,甚至引起较大误差。为了分析智能电能表动态误差的来源,该文采用机理建模的方法分别建立智能电能表电压通道、具有可编程增益放大器（programmable gain amplifier,PG...电网中特大功率负荷的功率动态变化对智能电能表产生不同程度的影响,甚至引起较大误差。为了分析智能电能表动态误差的来源,该文采用机理建模的方法分别建立智能电能表电压通道、具有可编程增益放大器（programmable gain amplifier,PGA）增益反馈控制的电流通道、有功功率测量单元及电能测量单元的动态数学模型,并集成各单元之间的信号传递关系,综合建立智能电能表全系统模型。以此为基础,建立动态误差仿真平台,分析各单元的模型参数对有功电能动态误差的影响。通过搭建动态误差测试系统,测试典型电能表的动态误差,与仿真分析结果的对比表明,该文提出的全系统模型可用于分析电能表动态条件下的内部误差影响因素、明确误差来源。研究结果可为后续提高智能电能表的动态性能提供定量的决策参考。展开更多
With the rapid development of network technology, the meaning of layers and attributes in respect of information system security must be extended based on the understanding of the concept of information system securit...With the rapid development of network technology, the meaning of layers and attributes in respect of information system security must be extended based on the understanding of the concept of information system security. The layering model (LM) of information system security and the five-attribute model (FAM) based on security factors were put forward to perfect the description and modeling of the information system security framework. An effective framework system of risk calculation and assessment was proposed, which is based on FAM.展开更多
This paper describes the ocean loading tides corrections of GPS stations in Antarctica, such as the Great Wall station and Zhongshan station. Based on the theory of ocean loading tides, the displacement corrections of...This paper describes the ocean loading tides corrections of GPS stations in Antarctica, such as the Great Wall station and Zhongshan station. Based on the theory of ocean loading tides, the displacement corrections of ocean loading tides on GPS stations in Antarctica are calculated by using the CRS4.0 ocean loading tides model. These corrections are also applied to GPS data proc-essing. The GPS data are analyzed by the GAMIT software with and without these corrections. We compared and analyzed the GPS baseline components to get the differences. The results show that the ocean tidal displacement corrections have obvious effects upon GPS baseline components. Therefore, we should not ignore the ocean loading tides corrections of GPS stations in Antarctica to obtain precise and reliable results.展开更多
Estimating the global position of a road vehicle without using GPS is a challenge that many scientists look forward to solving in the near future. Normally, inertial and odometry sensors are used to complement GPS mea...Estimating the global position of a road vehicle without using GPS is a challenge that many scientists look forward to solving in the near future. Normally, inertial and odometry sensors are used to complement GPS measures in an attempt to provide a means for maintaining vehicle odometry during GPS outage. Nonetheless, recent experiments have demonstrated that computer vision can also be used as a valuable source to provide what can be denoted as visual odometry. For this purpose, vehicle motion can be estimated using a non-linear, photogrametric approach based on RAndom SAmple Consensus (RANSAC). The results prove that the detection and selection of relevant feature points is a crucial factor in the global performance of the visual odometry algorithm. The key issues for further improvement are discussed in this letter.展开更多
In this paper, the TEC in China region is calculated by final GIM model and plotted as contour maps, the TEC value calculated from dual frequency GPS measurements(carrier-phase and pseudorange) is used as the referenc...In this paper, the TEC in China region is calculated by final GIM model and plotted as contour maps, the TEC value calculated from dual frequency GPS measurements(carrier-phase and pseudorange) is used as the reference truth and the TEC values from GIM models are then compared with the reference truth, and the accuracy and performance of GIM model in China region are analyzed and concluded.展开更多
In order to ensure the security of information systems, it's essential to make sure that system behaviors are trusted. By analyzing threats that exist in executing procedures, a trust model based on structured pro...In order to ensure the security of information systems, it's essential to make sure that system behaviors are trusted. By analyzing threats that exist in executing procedures, a trust model based on structured protection is proposed. We consider that functional components, system actions and message flows between components are three key factors of information systems. Structured protection requirements on components, connections and action parameters are also provided. Four trusted properties of the model are deducted through formal analysis, and trusted system behavior is defined based on these properties. Furthermore, decision theorem of trusted system behavior is proved. The developed prototype system indicates the model is practical. It is a general theory model built on logic deduction and independent on specific environment and the behaviors of the system designed and implemented following the model are trusted.展开更多
The characteristics of three GPS kinematic data processing models, Least Squares （LS）, Kalman filtering and filtering are discussed and their advantages and disadvantages are compared. With observational data and p...The characteristics of three GPS kinematic data processing models, Least Squares （LS）, Kalman filtering and filtering are discussed and their advantages and disadvantages are compared. With observational data and pertinent data processing software, the applicable condition, context and effect of the three models are experimented. Results show that when the mobile platform is in uniform motion, the accuracy of the three models are almost equal; when the mobile platform is in stochastic acceleration, the accuracy of H∞ filtering model is superior to that of LS, while that of Kalman filtering is the worst.展开更多
For program behavior-based anomaly detection, the only way to ensure accurate monitoring is to construct an efficient and precise program behavior model. A new program behavior-based anomaly detection model, called co...For program behavior-based anomaly detection, the only way to ensure accurate monitoring is to construct an efficient and precise program behavior model. A new program behavior-based anomaly detection model, called combined pushdown automaton (CPDA) model was proposed, which is based on static binary executable analysis. The CPDA model incorporates the optimized call stack walk and code instrumentation technique to gain complete context information. Thereby the proposed method can detect more attacks, while retaining good performance.展开更多
文摘电网中特大功率负荷的功率动态变化对智能电能表产生不同程度的影响,甚至引起较大误差。为了分析智能电能表动态误差的来源,该文采用机理建模的方法分别建立智能电能表电压通道、具有可编程增益放大器（programmable gain amplifier,PGA）增益反馈控制的电流通道、有功功率测量单元及电能测量单元的动态数学模型,并集成各单元之间的信号传递关系,综合建立智能电能表全系统模型。以此为基础,建立动态误差仿真平台,分析各单元的模型参数对有功电能动态误差的影响。通过搭建动态误差测试系统,测试典型电能表的动态误差,与仿真分析结果的对比表明,该文提出的全系统模型可用于分析电能表动态条件下的内部误差影响因素、明确误差来源。研究结果可为后续提高智能电能表的动态性能提供定量的决策参考。
文摘With the rapid development of network technology, the meaning of layers and attributes in respect of information system security must be extended based on the understanding of the concept of information system security. The layering model (LM) of information system security and the five-attribute model (FAM) based on security factors were put forward to perfect the description and modeling of the information system security framework. An effective framework system of risk calculation and assessment was proposed, which is based on FAM.
基金the National 863 Program of China (No.2007AA12Z312)
文摘This paper describes the ocean loading tides corrections of GPS stations in Antarctica, such as the Great Wall station and Zhongshan station. Based on the theory of ocean loading tides, the displacement corrections of ocean loading tides on GPS stations in Antarctica are calculated by using the CRS4.0 ocean loading tides model. These corrections are also applied to GPS data proc-essing. The GPS data are analyzed by the GAMIT software with and without these corrections. We compared and analyzed the GPS baseline components to get the differences. The results show that the ocean tidal displacement corrections have obvious effects upon GPS baseline components. Therefore, we should not ignore the ocean loading tides corrections of GPS stations in Antarctica to obtain precise and reliable results.
文摘Estimating the global position of a road vehicle without using GPS is a challenge that many scientists look forward to solving in the near future. Normally, inertial and odometry sensors are used to complement GPS measures in an attempt to provide a means for maintaining vehicle odometry during GPS outage. Nonetheless, recent experiments have demonstrated that computer vision can also be used as a valuable source to provide what can be denoted as visual odometry. For this purpose, vehicle motion can be estimated using a non-linear, photogrametric approach based on RAndom SAmple Consensus (RANSAC). The results prove that the detection and selection of relevant feature points is a crucial factor in the global performance of the visual odometry algorithm. The key issues for further improvement are discussed in this letter.
文摘In this paper, the TEC in China region is calculated by final GIM model and plotted as contour maps, the TEC value calculated from dual frequency GPS measurements(carrier-phase and pseudorange) is used as the reference truth and the TEC values from GIM models are then compared with the reference truth, and the accuracy and performance of GIM model in China region are analyzed and concluded.
基金supported by National Science and Technology Major Project under Grant No.2012ZX03002003Funds of Key Lab of Fujian Province University Network Security and Cryptology under Grant No.2011009Open Research Project of State Key Laboratory of Information Security in Institute of Software,Chinese Academy of Sciences
文摘In order to ensure the security of information systems, it's essential to make sure that system behaviors are trusted. By analyzing threats that exist in executing procedures, a trust model based on structured protection is proposed. We consider that functional components, system actions and message flows between components are three key factors of information systems. Structured protection requirements on components, connections and action parameters are also provided. Four trusted properties of the model are deducted through formal analysis, and trusted system behavior is defined based on these properties. Furthermore, decision theorem of trusted system behavior is proved. The developed prototype system indicates the model is practical. It is a general theory model built on logic deduction and independent on specific environment and the behaviors of the system designed and implemented following the model are trusted.
基金the National Natural Foundation of China (No.40574002)the Natural Foundation of Guang Xi Zhuang Autonomous Re-gion (No. 0728097)
文摘The characteristics of three GPS kinematic data processing models, Least Squares （LS）, Kalman filtering and filtering are discussed and their advantages and disadvantages are compared. With observational data and pertinent data processing software, the applicable condition, context and effect of the three models are experimented. Results show that when the mobile platform is in uniform motion, the accuracy of the three models are almost equal; when the mobile platform is in stochastic acceleration, the accuracy of H∞ filtering model is superior to that of LS, while that of Kalman filtering is the worst.
文摘For program behavior-based anomaly detection, the only way to ensure accurate monitoring is to construct an efficient and precise program behavior model. A new program behavior-based anomaly detection model, called combined pushdown automaton (CPDA) model was proposed, which is based on static binary executable analysis. The CPDA model incorporates the optimized call stack walk and code instrumentation technique to gain complete context information. Thereby the proposed method can detect more attacks, while retaining good performance.
