A smart homing guidance strategy with control saturation against a target-defender team is derived. It is noteworthy that a cooperative strategy of the target-defender team is applied,which has been proved more challe...A smart homing guidance strategy with control saturation against a target-defender team is derived. It is noteworthy that a cooperative strategy of the target-defender team is applied,which has been proved more challenging for the homing guidance.The defender missile is launched by the target and guided by a cooperative augmented proportional navigation(APN). At the same time, the target performs a one-switch maneuver to cooperate and minimize the defender's acceleration requirement. The problem is analyzed for arbitrary-order linear dynamics of the agents in the linearized form but validated by the mathematical simulations by using nonlinear kinematics. The perfect information of three agents' states is assumed. Then, a method to deal with the target-defender team is proposed. It contains a combined performance index penalizing the miss distance relative to the target and energy consumption in the whole duration. Besides, the specific miss distance related to the defender is regarded as an inequality constraint. An analytical solution for the smart guidance strategy against the APN guided defender is derived. Meanwhile, the control saturations are introduced to get more realistic and reasonable insights to this practical target-missile-defender problem. A simple but effective iterative searching technique is proposed to determine the saturation time points. The solution provides an optimal homing strategy to evade the defender with a specific miss distance and intercept the target with the minimum miss distance in the minimum energy manner. Nonlinear two-dimensional simulation results are used to validate the theoretical analysis. By comparison with the optimal differential game guidance(ODGG) and the combined minimum effort guidance(CMEG), the superiority of this smart guidance strategy is concluded.展开更多
An approach of defending against Distributed Denial of Service (DDoS) attack based on flow model and flow detection is presented. The proposed approach can protect targets from DDoS attacking, and allow targets to pro...An approach of defending against Distributed Denial of Service (DDoS) attack based on flow model and flow detection is presented. The proposed approach can protect targets from DDoS attacking, and allow targets to provide good service to legitimate traffic under DDoS attacking, with fast reaction. This approach adopts the technique of dynamic comb filter, yields a low level of false positives of less than 1.5%, drops similar percentage of good traffic, about 1%, and passes neglectable percentage of attack bandwidth to the victim, less than 1.5%. The prototype of commercial product, D-fighter, is developed by implementing this proposed approach on Intel network processor platform IXP1200.展开更多
As to oppositional, multi-objective and hierarchical characteristic of air formation to ground attackdefends campaign, and using dynamic space state model of military campaign, this article establishes a principal and...As to oppositional, multi-objective and hierarchical characteristic of air formation to ground attackdefends campaign, and using dynamic space state model of military campaign, this article establishes a principal and subordinate hierarchical interactive decision-making way, the Nash-Stackelberg-Nash model, to solve the problems in military operation, and find out the associated best strategy in hierarchical dynamic decision-making. The simulating result indicate that when applying the model to air formation to ground attack-defends decision-making system, it can solve the problems of two hierarchies, dynamic oppositional decision-making favorably, and reach preferable effect in battle. It proves that the model can provide an effective way for analyzing a battle,展开更多
The hero in the masterpiece of Charlotte Bronte Jane Eyre--Edward Rochester acts as a faithful defender on the matter of his marriage with Bertha Mason. His compliance with the patriarchal rules mostly displays in thr...The hero in the masterpiece of Charlotte Bronte Jane Eyre--Edward Rochester acts as a faithful defender on the matter of his marriage with Bertha Mason. His compliance with the patriarchal rules mostly displays in three aspects, that is, male dominant household, men's superiority to women in law, and man's supremacy in marriage.展开更多
LIU Jie still remembers the challenges she faced in the fight against the AIDS epidemic during her stint as a medical volunteer in Nigeria six years ago. Ironically, it was not the lack of medicine or funding that was...LIU Jie still remembers the challenges she faced in the fight against the AIDS epidemic during her stint as a medical volunteer in Nigeria six years ago. Ironically, it was not the lack of medicine or funding that was the biggest hurdle, but the difficulty in effectively delivering the treatment drugs and services.展开更多
Objectives:This study investigates the association between victimization experience and the tendency to defend on behalf of victims during school bullying incidents in public settings,with a focus on the mediating eff...Objectives:This study investigates the association between victimization experience and the tendency to defend on behalf of victims during school bullying incidents in public settings,with a focus on the mediating effect of empathy and the moderating role of school level among Chinese children and adolescents.Methods:Data were collected by a cross-sectional survey.A total of 1491 students in Grades 4–11 participated(Boys=52.8%;Mean_(age)=13.00 years,Standard Deviation_(age)=2.31).Structural equation modeling is employed to test the hypotheses.Results:The results indicate that empathy measures partially mediate the relationship between victimization experience and defending tendency in public in-school bullying situations.In particular,individuals with a history of victimization typically demonstrate lower levels of empathy.They are less likely to protect victims in school bullying situations in the presence of others,which suggests that empathy plays a significant mediating role in this relationship.Group differences were found between primary and secondary school students,which indicates that the hypothesized model should be considered through a developmental perspective.Conclusions:The findings of this study emphasize the importance of children’s benign peer relationships,and practitioners are encouraged to prevent victimization in schools and care for students who have been victimized;specific measures include cultivating empathy,teaching defending skills that have been found to help reduce the adverse effects of victimization,and encouraging prosocial behavior during children's socialization development.展开更多
A much-anticipated law protecting homeowners’ rights is on the horizon Television audiences around the country were shocked on November 21,2009,when national broadcaster China Central Television showed clips of two f...A much-anticipated law protecting homeowners’ rights is on the horizon Television audiences around the country were shocked on November 21,2009,when national broadcaster China Central Television showed clips of two families violently fighting lawenforcement officials who were evicting them from their homes.展开更多
Defending the many with the few" is an effectivetraining method to enhance the defensive ability of the whole team. The results of this study indicated that through the system of two-on-three, three-on-four and f...Defending the many with the few" is an effectivetraining method to enhance the defensive ability of the whole team. The results of this study indicated that through the system of two-on-three, three-on-four and four -on-five and intensified training, players could impove themselves in a short period in collective abilitys and consciousness, such as choosing position, adjusting position, coordinating defence and shifting defence. And team ability and style could thus be trained.展开更多
A defender–attacker–target problem with non-moving target is considered.This problem is modelled by a pursuit-evasion zero-sum differential game with linear dynamics and quadratic cost functional.In this game,the pu...A defender–attacker–target problem with non-moving target is considered.This problem is modelled by a pursuit-evasion zero-sum differential game with linear dynamics and quadratic cost functional.In this game,the pursuer is the defender,while the evader is the attacker.The objective of the pursuer is to minimise the cost functional,while the evader has two objectives:to maximise the cost functional and to keep a given terminal state inequality constraint.The open-loop saddle point solution of this game is obtained in the case where the transfer functions of the controllers for the defender and the attacker are of arbitrary orders.展开更多
基金supported by the National Natural Science Foundation of China(91216104 61503302)
文摘A smart homing guidance strategy with control saturation against a target-defender team is derived. It is noteworthy that a cooperative strategy of the target-defender team is applied,which has been proved more challenging for the homing guidance.The defender missile is launched by the target and guided by a cooperative augmented proportional navigation(APN). At the same time, the target performs a one-switch maneuver to cooperate and minimize the defender's acceleration requirement. The problem is analyzed for arbitrary-order linear dynamics of the agents in the linearized form but validated by the mathematical simulations by using nonlinear kinematics. The perfect information of three agents' states is assumed. Then, a method to deal with the target-defender team is proposed. It contains a combined performance index penalizing the miss distance relative to the target and energy consumption in the whole duration. Besides, the specific miss distance related to the defender is regarded as an inequality constraint. An analytical solution for the smart guidance strategy against the APN guided defender is derived. Meanwhile, the control saturations are introduced to get more realistic and reasonable insights to this practical target-missile-defender problem. A simple but effective iterative searching technique is proposed to determine the saturation time points. The solution provides an optimal homing strategy to evade the defender with a specific miss distance and intercept the target with the minimum miss distance in the minimum energy manner. Nonlinear two-dimensional simulation results are used to validate the theoretical analysis. By comparison with the optimal differential game guidance(ODGG) and the combined minimum effort guidance(CMEG), the superiority of this smart guidance strategy is concluded.
基金Supported by the National High Technology Research and Development Program of China (863 Program)(No.2003AA142080, 2005AA775060)the National Natural Sicence Foundation of China(No.60203004)National Basic Research Program of China (973Program) (No.2003CB314805)the National Outstanding Youth Foundation (No.60325102)
文摘An approach of defending against Distributed Denial of Service (DDoS) attack based on flow model and flow detection is presented. The proposed approach can protect targets from DDoS attacking, and allow targets to provide good service to legitimate traffic under DDoS attacking, with fast reaction. This approach adopts the technique of dynamic comb filter, yields a low level of false positives of less than 1.5%, drops similar percentage of good traffic, about 1%, and passes neglectable percentage of attack bandwidth to the victim, less than 1.5%. The prototype of commercial product, D-fighter, is developed by implementing this proposed approach on Intel network processor platform IXP1200.
基金College Doctor Foundation (20060699026)Aviation Basic Scientific Foundation (05D53021).
文摘As to oppositional, multi-objective and hierarchical characteristic of air formation to ground attackdefends campaign, and using dynamic space state model of military campaign, this article establishes a principal and subordinate hierarchical interactive decision-making way, the Nash-Stackelberg-Nash model, to solve the problems in military operation, and find out the associated best strategy in hierarchical dynamic decision-making. The simulating result indicate that when applying the model to air formation to ground attack-defends decision-making system, it can solve the problems of two hierarchies, dynamic oppositional decision-making favorably, and reach preferable effect in battle. It proves that the model can provide an effective way for analyzing a battle,
文摘The hero in the masterpiece of Charlotte Bronte Jane Eyre--Edward Rochester acts as a faithful defender on the matter of his marriage with Bertha Mason. His compliance with the patriarchal rules mostly displays in three aspects, that is, male dominant household, men's superiority to women in law, and man's supremacy in marriage.
文摘LIU Jie still remembers the challenges she faced in the fight against the AIDS epidemic during her stint as a medical volunteer in Nigeria six years ago. Ironically, it was not the lack of medicine or funding that was the biggest hurdle, but the difficulty in effectively delivering the treatment drugs and services.
基金supported by the Philosophy and Social Science Foundation of Hunan Province(Grant Number 21YBQ005).
文摘Objectives:This study investigates the association between victimization experience and the tendency to defend on behalf of victims during school bullying incidents in public settings,with a focus on the mediating effect of empathy and the moderating role of school level among Chinese children and adolescents.Methods:Data were collected by a cross-sectional survey.A total of 1491 students in Grades 4–11 participated(Boys=52.8%;Mean_(age)=13.00 years,Standard Deviation_(age)=2.31).Structural equation modeling is employed to test the hypotheses.Results:The results indicate that empathy measures partially mediate the relationship between victimization experience and defending tendency in public in-school bullying situations.In particular,individuals with a history of victimization typically demonstrate lower levels of empathy.They are less likely to protect victims in school bullying situations in the presence of others,which suggests that empathy plays a significant mediating role in this relationship.Group differences were found between primary and secondary school students,which indicates that the hypothesized model should be considered through a developmental perspective.Conclusions:The findings of this study emphasize the importance of children’s benign peer relationships,and practitioners are encouraged to prevent victimization in schools and care for students who have been victimized;specific measures include cultivating empathy,teaching defending skills that have been found to help reduce the adverse effects of victimization,and encouraging prosocial behavior during children's socialization development.
文摘A much-anticipated law protecting homeowners’ rights is on the horizon Television audiences around the country were shocked on November 21,2009,when national broadcaster China Central Television showed clips of two families violently fighting lawenforcement officials who were evicting them from their homes.
文摘Defending the many with the few" is an effectivetraining method to enhance the defensive ability of the whole team. The results of this study indicated that through the system of two-on-three, three-on-four and four -on-five and intensified training, players could impove themselves in a short period in collective abilitys and consciousness, such as choosing position, adjusting position, coordinating defence and shifting defence. And team ability and style could thus be trained.
文摘A defender–attacker–target problem with non-moving target is considered.This problem is modelled by a pursuit-evasion zero-sum differential game with linear dynamics and quadratic cost functional.In this game,the pursuer is the defender,while the evader is the attacker.The objective of the pursuer is to minimise the cost functional,while the evader has two objectives:to maximise the cost functional and to keep a given terminal state inequality constraint.The open-loop saddle point solution of this game is obtained in the case where the transfer functions of the controllers for the defender and the attacker are of arbitrary orders.
