僵尸网络(Botnet)是一种从传统恶意代码形态进化而来的新型攻击方式,为攻击者提供了隐匿、灵活且高效的一对多命令与控制信道(Command and Control channel,C&C)机制,可以控制大量僵尸主机实现信息窃取、分布式拒绝服务攻击和垃圾...僵尸网络(Botnet)是一种从传统恶意代码形态进化而来的新型攻击方式,为攻击者提供了隐匿、灵活且高效的一对多命令与控制信道(Command and Control channel,C&C)机制,可以控制大量僵尸主机实现信息窃取、分布式拒绝服务攻击和垃圾邮件发送等攻击目的。该文提出一种与僵尸网络结构和C&C协议无关,不需要分析数据包的特征负载的僵尸网络检测方法。该方法首先使用预过滤规则对捕获的流量进行过滤,去掉与僵尸网络无关的流量;其次对过滤后的流量属性进行统计;接着使用基于X-means聚类的两步聚类算法对C&C信道的流量属性进行分析与聚类,从而达到对僵尸网络检测的目的。实验证明,该方法高效准确地把僵尸网络流量与其他正常网络流量区分,达到从实际网络中检测僵尸网络的要求,并且具有较低的误判率。展开更多
Adaptive optimization is one of the means that agile organization of command and control resource （AOC2R） adapts for the dynamic battlefield environment. A math model of the adaptive optimization of AOC2R is put for...Adaptive optimization is one of the means that agile organization of command and control resource （AOC2R） adapts for the dynamic battlefield environment. A math model of the adaptive optimization of AOC2R is put forward by analyzing the interrelating concept and research. The model takes the adaptive process as a multi-stage decision making problem. The 2-phases method is presented to calculate the model, which obtains the related parameters by running the colored Petri net （CPN） model of AOC2R and then searches for the result by ant colony optimization （ACO） algorithm integrated with genetic optimization techniques. The simulation results demonstrate that the proposed algorithm greatly improves the performance of AOC2R.展开更多
The global economic downturn caused primarily by the US sub-prime mortgage crisis in 2007 engendered revenue loss of the multinational corporations. Existing studies have yet to depict the detrimental impacts on city...The global economic downturn caused primarily by the US sub-prime mortgage crisis in 2007 engendered revenue loss of the multinational corporations. Existing studies have yet to depict the detrimental impacts on city＇s command and control functions induced by the sub-prime mortgage crisis together with its residual wave of global economic recession on the global spatial economy. Recent and previous studies have produced an ＇instant history＇ of the global spatial economy before the global economic downturn undermines the global economy in late 2008. How- ever, the waxes and wanes of major cities＇ command and control functions on the global economic arena before and after the outbreak of financial crisis and its associated geo-economic transitions are still poorly understood. This paper attempts to contribute a new set of customized data to update and fill in the gap in the literature with the investigation of the command and control functions of cities arotmd the world from 2005 to 2009. Particular attentions are paid to the time-space relationship of the geo-economic transition that can capture the recent historical images of the com- mand and control situation of different cities in the world.展开更多
New precisely cooperative attacks, such as the coordi- nated cross plane session termination （CXPST） attack, need thou- sands upon thousands machines to attack diverse selected links simultaneously with the given ra...New precisely cooperative attacks, such as the coordi- nated cross plane session termination （CXPST） attack, need thou- sands upon thousands machines to attack diverse selected links simultaneously with the given rate. However, almost all command and control（C＆C） mechanisms only provide publishing one com- mand to the whole once, so-called one-to-all C＆C model, and are not productive to support CXPST-alike attacks. In this paper, we present one-to-any C＆C model on coordination among the unco- operative controlled nodes. As an instance of one-to-any C＆C model, directional command publishing （DCP） mechanism lever- aging on Kademlia is provided with a range-mapping key creating algorithm for commands to compute the publishing range and a statistically stochastic node querying scheme to obtain the com- mands immediately. With theoretical analysis and simulation, it is indicated that one-to-any C＆C model fits for precisely coordi- nated operation on uncooperative controlled nodes with least complexity, better accuracy and efficiency. Furthermore, DCP mechanism can support one-to-all command publishing at the same time. As an example of future C＆C model, studying on one-to-any C＆C model may help to promote the development of more efficient countermeasures.展开更多
The impact of environmental regulation on technology innovation is a hot spot in current research where a large number of empirical studies are based on Porter Hypothesis(PH). However, there are still controversies in...The impact of environmental regulation on technology innovation is a hot spot in current research where a large number of empirical studies are based on Porter Hypothesis(PH). However, there are still controversies in academia about the establishment of "weak" and "narrow" versions of PH. Based on the panel data of application for patent of energy conservation and emission reduction(ECER) technology of Chinese city scale during 2008-2014, comprehensive energy price, pollutant emission, etc., mixed regression model and systematic generalized method of moments method were adopted, respectively,to study the impact of market-oriented and command-and-control policy tool on China's ECER technology innovation. The results show that the environmental regulation hindered the technological innovation in the immediate phase; however, it turned out to be positive in the first-lag phase. Hence, the establishment of "weak" PH is time-bounded. The command-and-control policy tool played a more positive role in promoting technological innovation in the first-lag phase than market-oriented policy tool. Therefore, "narrow" PH is not tenable. The reason is that the main participants of China's ECER technology innovation are state-owned companies and public institutions. Regionally speaking, the impact which command-and-control policy tool has on technological innovation at sight was nonsignificant in the eastern, the central, and the western regions of China whilst market-oriented policy tool had a negative effect. And market-oriented policy tool in the central region had strongest negative effect, which would diminish in the eastern region and become weakest in the western region. This was related to regional energy consumption level and the market economic vitality.展开更多
Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with param...Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.展开更多
In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated...In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.展开更多
新能源出力大幅波动下区域控制偏差(area control error,ACE)中出现不平衡调节量,导致其不能准确表征系统调频需求。由此生成的储能自动发电控制(automatic generation control,AGC)指令与储能一次调频指令冲突,从而引发储能调频响应效...新能源出力大幅波动下区域控制偏差(area control error,ACE)中出现不平衡调节量,导致其不能准确表征系统调频需求。由此生成的储能自动发电控制(automatic generation control,AGC)指令与储能一次调频指令冲突,从而引发储能调频响应效率低下问题。针对现有储能控制策略调频需求分配与协调合理性不足的问题,该文首先从储能调频指令冲突演化过程剖析指令冲突成因,进一步考虑调频指令冲突抑制与优化分配,提出一种分层调频控制策略,包括区域调度层、指令协调层和储能优化层。区域调度层根据电网调频需求划分死区、正常调节区和紧急调节区,确定各区间出力目标以协调储能与常规机组的功率分配;指令协调层针对储能调频指令同向和反向调节情况,分别提出基于指令优先级和考虑指令协调附加系数的动态协调方法以抑制调频指令冲突;储能优化层考虑多储能单元的功率特性和能量特性,计算权重调整系数以优化多储能单元间出力分配。在MATLAB/Simulink中进行仿真并选取电网实际运行数据进一步验证策略的有效性,结果表明,所提策略实现了储能调频指令的合理分配与协调控制,显著提升了电网频率调节的稳定性和效率。展开更多
文摘僵尸网络(Botnet)是一种从传统恶意代码形态进化而来的新型攻击方式,为攻击者提供了隐匿、灵活且高效的一对多命令与控制信道(Command and Control channel,C&C)机制,可以控制大量僵尸主机实现信息窃取、分布式拒绝服务攻击和垃圾邮件发送等攻击目的。该文提出一种与僵尸网络结构和C&C协议无关,不需要分析数据包的特征负载的僵尸网络检测方法。该方法首先使用预过滤规则对捕获的流量进行过滤,去掉与僵尸网络无关的流量;其次对过滤后的流量属性进行统计;接着使用基于X-means聚类的两步聚类算法对C&C信道的流量属性进行分析与聚类,从而达到对僵尸网络检测的目的。实验证明,该方法高效准确地把僵尸网络流量与其他正常网络流量区分,达到从实际网络中检测僵尸网络的要求,并且具有较低的误判率。
文摘Adaptive optimization is one of the means that agile organization of command and control resource （AOC2R） adapts for the dynamic battlefield environment. A math model of the adaptive optimization of AOC2R is put forward by analyzing the interrelating concept and research. The model takes the adaptive process as a multi-stage decision making problem. The 2-phases method is presented to calculate the model, which obtains the related parameters by running the colored Petri net （CPN） model of AOC2R and then searches for the result by ant colony optimization （ACO） algorithm integrated with genetic optimization techniques. The simulation results demonstrate that the proposed algorithm greatly improves the performance of AOC2R.
基金Foundation item:Under the auspices of Hui Oi Chow Trust Fund(No.200902172004)Mrs.Li Ka Shing Fund,Strategic Research Theme on Contemporary China,Small Project Funding provided by the University of Hong Kong(No.200807176152)
文摘The global economic downturn caused primarily by the US sub-prime mortgage crisis in 2007 engendered revenue loss of the multinational corporations. Existing studies have yet to depict the detrimental impacts on city＇s command and control functions induced by the sub-prime mortgage crisis together with its residual wave of global economic recession on the global spatial economy. Recent and previous studies have produced an ＇instant history＇ of the global spatial economy before the global economic downturn undermines the global economy in late 2008. How- ever, the waxes and wanes of major cities＇ command and control functions on the global economic arena before and after the outbreak of financial crisis and its associated geo-economic transitions are still poorly understood. This paper attempts to contribute a new set of customized data to update and fill in the gap in the literature with the investigation of the command and control functions of cities arotmd the world from 2005 to 2009. Particular attentions are paid to the time-space relationship of the geo-economic transition that can capture the recent historical images of the com- mand and control situation of different cities in the world.
基金Supported by the National Natural Science Foundation of China(61402526,61502528)
文摘New precisely cooperative attacks, such as the coordi- nated cross plane session termination （CXPST） attack, need thou- sands upon thousands machines to attack diverse selected links simultaneously with the given rate. However, almost all command and control（C＆C） mechanisms only provide publishing one com- mand to the whole once, so-called one-to-all C＆C model, and are not productive to support CXPST-alike attacks. In this paper, we present one-to-any C＆C model on coordination among the unco- operative controlled nodes. As an instance of one-to-any C＆C model, directional command publishing （DCP） mechanism lever- aging on Kademlia is provided with a range-mapping key creating algorithm for commands to compute the publishing range and a statistically stochastic node querying scheme to obtain the com- mands immediately. With theoretical analysis and simulation, it is indicated that one-to-any C＆C model fits for precisely coordi- nated operation on uncooperative controlled nodes with least complexity, better accuracy and efficiency. Furthermore, DCP mechanism can support one-to-all command publishing at the same time. As an example of future C＆C model, studying on one-to-any C＆C model may help to promote the development of more efficient countermeasures.
文摘The impact of environmental regulation on technology innovation is a hot spot in current research where a large number of empirical studies are based on Porter Hypothesis(PH). However, there are still controversies in academia about the establishment of "weak" and "narrow" versions of PH. Based on the panel data of application for patent of energy conservation and emission reduction(ECER) technology of Chinese city scale during 2008-2014, comprehensive energy price, pollutant emission, etc., mixed regression model and systematic generalized method of moments method were adopted, respectively,to study the impact of market-oriented and command-and-control policy tool on China's ECER technology innovation. The results show that the environmental regulation hindered the technological innovation in the immediate phase; however, it turned out to be positive in the first-lag phase. Hence, the establishment of "weak" PH is time-bounded. The command-and-control policy tool played a more positive role in promoting technological innovation in the first-lag phase than market-oriented policy tool. Therefore, "narrow" PH is not tenable. The reason is that the main participants of China's ECER technology innovation are state-owned companies and public institutions. Regionally speaking, the impact which command-and-control policy tool has on technological innovation at sight was nonsignificant in the eastern, the central, and the western regions of China whilst market-oriented policy tool had a negative effect. And market-oriented policy tool in the central region had strongest negative effect, which would diminish in the eastern region and become weakest in the western region. This was related to regional energy consumption level and the market economic vitality.
文摘Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.
文摘In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.
文摘新能源出力大幅波动下区域控制偏差(area control error,ACE)中出现不平衡调节量,导致其不能准确表征系统调频需求。由此生成的储能自动发电控制(automatic generation control,AGC)指令与储能一次调频指令冲突,从而引发储能调频响应效率低下问题。针对现有储能控制策略调频需求分配与协调合理性不足的问题,该文首先从储能调频指令冲突演化过程剖析指令冲突成因,进一步考虑调频指令冲突抑制与优化分配,提出一种分层调频控制策略,包括区域调度层、指令协调层和储能优化层。区域调度层根据电网调频需求划分死区、正常调节区和紧急调节区,确定各区间出力目标以协调储能与常规机组的功率分配;指令协调层针对储能调频指令同向和反向调节情况,分别提出基于指令优先级和考虑指令协调附加系数的动态协调方法以抑制调频指令冲突;储能优化层考虑多储能单元的功率特性和能量特性,计算权重调整系数以优化多储能单元间出力分配。在MATLAB/Simulink中进行仿真并选取电网实际运行数据进一步验证策略的有效性,结果表明,所提策略实现了储能调频指令的合理分配与协调控制,显著提升了电网频率调节的稳定性和效率。
