This paper addresses the time-varying formation-containment(FC) problem for nonholonomic multi-agent systems with a desired trajectory constraint, where only the leaders can acquire information about the desired traje...This paper addresses the time-varying formation-containment(FC) problem for nonholonomic multi-agent systems with a desired trajectory constraint, where only the leaders can acquire information about the desired trajectory. Input the fixed time-varying formation template to the leader and start executing, this process also needs to track the desired trajectory, and the follower needs to converge to the convex hull that the leader crosses. Firstly, the dynamic models of nonholonomic systems are linearized to second-order dynamics. Then, based on the desired trajectory and formation template, the FC control protocols are proposed. Sufficient conditions to achieve FC are introduced and an algorithm is proposed to resolve the control parameters by solving an algebraic Riccati equation. The system is demonstrated to achieve FC, with the average position and velocity of the leaders converging asymptotically to the desired trajectory. Finally, the theoretical achievements are verified in simulations by a multi-agent system composed of virtual human individuals.展开更多
It is necessary for legged robots to walk stably and smoothly on rough terrain.In this paper,a desired landing points(DLP) walking method based on preview control was proposed in which an off-line foot motion trace an...It is necessary for legged robots to walk stably and smoothly on rough terrain.In this paper,a desired landing points(DLP) walking method based on preview control was proposed in which an off-line foot motion trace and an on-line modification of the trace were used to enable the robot to walk on rough terrain.The on-line modification was composed of speed modification,foot lifting-off height modification,step length modification,and identification and avoidance of unsuitable landing terrain.A planner quadruped robot simulator was used to apply the DLP walking method.The correctness of the method was proven by a series of simulations using the Adams and Simulink.展开更多
In this paper, we propose an effective full array and sparse array adaptive beamforming scheme that can be applied for multiple desired signals based on the branch-and-bound algorithm. Adaptive beamforming for the mul...In this paper, we propose an effective full array and sparse array adaptive beamforming scheme that can be applied for multiple desired signals based on the branch-and-bound algorithm. Adaptive beamforming for the multiple desired signals is realized by the improved Capon method. At the same time,the sidelobe constraint is added to reduce the sidelobe level. To reduce the pointing errors of multiple desired signals, the array response phase of the desired signal is firstly optimized by using auxilary variables while keeping the response amplitude unchanged. The whole design is formulated as a convex optimization problem solved by the branch-and-bound algorithm. In addition,the beamformer weight vector is penalized with the modified reweighted l_(1)-norm to achieve sparsity. Theoretical analysis and simulation results show that the proposed algorithm has lower sidelobe level, higher SINR, and less pointing error than the stateof-the-art methods in the case of a single expected signal and multiple desired signals.展开更多
Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissu...Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissue.However,maintaining the viability of a thick tissue structure during tissue growth and maturation is challenging due to lack of adequate vascular perfusion.In a simple tissue model with展开更多
英语中有些表示时间的名词,象moment,minute,instant,second,time,day,month,winter,year等等,可以用来引导时间状语从句。如: 1)I recognized him the moment I saw him. 2)She began taming about you the day we met. 句1)中的the mo...英语中有些表示时间的名词,象moment,minute,instant,second,time,day,month,winter,year等等,可以用来引导时间状语从句。如: 1)I recognized him the moment I saw him. 2)She began taming about you the day we met. 句1)中的the moment很象一个连词。展开更多
In this paper, solution to the LQ inverse problem has been pre-sented. With the control weight in an LQ optimal control system fixed,the state weighting matrix is parametrized in terms of a set of freevariables and th...In this paper, solution to the LQ inverse problem has been pre-sented. With the control weight in an LQ optimal control system fixed,the state weighting matrix is parametrized in terms of a set of freevariables and the closed-loop eigenvalues of the control system. Basedon this parametrization, an algorithmic procedure is proposed to deter-mine the state weighting matrix and the free variables by matrixtransformation. Meanwhile, by using the solved free variables, theoptimal feedback gain matrix K can also be obtained without solving thealgebraic Riccati equation.展开更多
英语教学的最终目标是培养交际能力,也就是培养学生自由对话的能力。对话是通过话语进行的思想与信息的一种非正式的交流。我们先看一段对话。这段对话是在两个受过教育的美国人之间进行的: A:Ev...Everybody has at least one little s...英语教学的最终目标是培养交际能力,也就是培养学生自由对话的能力。对话是通过话语进行的思想与信息的一种非正式的交流。我们先看一段对话。这段对话是在两个受过教育的美国人之间进行的: A:Ev...Everybody has at least one little superstition,don’t you think? B:I think most people have at least one,展开更多
To reduce the fuel consumption and emissions and also enhance the molten aluminum quality, a mathematical model with user-developed melting model and burning capacity model, were established according to the features ...To reduce the fuel consumption and emissions and also enhance the molten aluminum quality, a mathematical model with user-developed melting model and burning capacity model, were established according to the features of melting process of regenerative aluminum melting furnaces. Based on validating results by heat balance test for an aluminum melting furnace, CFD （computational fluid dynamics） technique, in association with statistical experimental design were used to optimize the melting process of the aluminum melting furnace. Four important factors influencing the melting time, such as horizontal angle between burners, height-to-radius ratio, natural gas mass flow and air preheated temperature, were identified by PLACKETT-BURMAN design. A steepest descent method was undertaken to determine the optimal regions of these factors. Response surface methodology with BOX-BEHNKEN design was adopted to further investigate the mutual interactions between these variables on RSD （relative standard deviation） of aluminum temperature, RSD of furnace temperature and melting time. Multiple-response optimization by desirability function approach was used to determine the optimum melting process parameters. The results indicate that the interaction between the height-to-radius ratio and horizontal angle between burners affects the response variables significantly. The predicted results show that the minimum RSD of aluminum temperature （12.13%）, RSD of furnace temperature （18.50%） and melting time （3.9 h） could be obtained under the optimum conditions of horizontal angle between burners as 64°, height-to-radius ratio as 0.3, natural gas mass flow as 599 m3/h, and air preheated temperature as 639 ℃. These predicted values were further verified by validation experiments. The excellent correlation between the predicted and experimental values confirms the validity and practicability of this statistical optimum strategy.展开更多
There is so much to read today that the ability to read quickly has become an important asset. It is fairly known that the faster readets will have more opportunity and more access to a greater range and quantity of r...There is so much to read today that the ability to read quickly has become an important asset. It is fairly known that the faster readets will have more opportunity and more access to a greater range and quantity of reading material which will give them enhanced pleasure and benifits. Had they not developed their faster reading skills the chances are that they would never have come across many important articles and documents. College students often have a desire and need to be generally informed in some other fields besides their major subjects such as political affairs or cuitur-展开更多
There are several web sites for whichinformation is available to the cotton researchcommunity.Most of these sites relate toresources developed or available to the researchcommunity.Few provide bioinformatic tools,whic...There are several web sites for whichinformation is available to the cotton researchcommunity.Most of these sites relate toresources developed or available to the researchcommunity.Few provide bioinformatic tools,which usually relate to the specific data sets andmaterials presented in the database.Just as thebioinformatics area is evolving,the展开更多
Green Virtual Enterprise (GVE) is a new contemporar y manufacturing mode, which is to adapt and meet the need of sustainable developme nt of humanity. In, this paper, the concept of Total Green Management is first a d...Green Virtual Enterprise (GVE) is a new contemporar y manufacturing mode, which is to adapt and meet the need of sustainable developme nt of humanity. In, this paper, the concept of Total Green Management is first a dvanced. In this based on the analysis of the Virtual Enterprise (VE) and Total Green Management (TGM), the concept of Green Virtual Enterprise and its architec ture is brought forward.展开更多
Goals reasoning and management of pilot is a key issue to monitor pilot's behavior and intention. Traditional modeling methods are based on scenarios or situations, such methods will cause the,covering problem due...Goals reasoning and management of pilot is a key issue to monitor pilot's behavior and intention. Traditional modeling methods are based on scenarios or situations, such methods will cause the,covering problem due to redundancy and are incapable of depicting interactions among various goals and plans of pilot. Petri net integrated with belief, desire and intention (BDI) theory (BDI Petri net) is designed to solve this problem. Focusing on the BDI theory, goal states of agent are discussed firstly. Belief, desire and intention are modeled by places and transitions based on the Petri net theory. In order to simplify the network, colored token is introduced to depict various states of belief, and the hierarchy transition is applied to model the intention, together with tokens' flow derrionstrating the interaction among various goals and relationship among belief, desire and intention. A search and rescue mission is used to validate the proposed method and the result indicates that the model can be used to monitor goals and behaviors of pilots.展开更多
英语中有些形容词因源于同一动词或名词,拼写有些相似,但发音及意义不同,有时候很容易混淆,往往导致用法及理解方面的错误。现汇集几组举例如下。 1、regrettable与regretful regrettable意为“令人遗憾的,可惜的”,只能用来修饰事物。 ...英语中有些形容词因源于同一动词或名词,拼写有些相似,但发音及意义不同,有时候很容易混淆,往往导致用法及理解方面的错误。现汇集几组举例如下。 1、regrettable与regretful regrettable意为“令人遗憾的,可惜的”,只能用来修饰事物。 例:It is regrettable that they have leftthe city already.很遗憾他们已经离开这个城市。展开更多
文摘This paper addresses the time-varying formation-containment(FC) problem for nonholonomic multi-agent systems with a desired trajectory constraint, where only the leaders can acquire information about the desired trajectory. Input the fixed time-varying formation template to the leader and start executing, this process also needs to track the desired trajectory, and the follower needs to converge to the convex hull that the leader crosses. Firstly, the dynamic models of nonholonomic systems are linearized to second-order dynamics. Then, based on the desired trajectory and formation template, the FC control protocols are proposed. Sufficient conditions to achieve FC are introduced and an algorithm is proposed to resolve the control parameters by solving an algebraic Riccati equation. The system is demonstrated to achieve FC, with the average position and velocity of the leaders converging asymptotically to the desired trajectory. Finally, the theoretical achievements are verified in simulations by a multi-agent system composed of virtual human individuals.
基金supported in part by the National Natural Science Foundation of China under Grant 60875067the Natural Science Foundation of Heilongjiang Province under Grant F200602the Technical Innovation Talent Foundation of Harbin under Grant 2010RFQXG010
文摘It is necessary for legged robots to walk stably and smoothly on rough terrain.In this paper,a desired landing points(DLP) walking method based on preview control was proposed in which an off-line foot motion trace and an on-line modification of the trace were used to enable the robot to walk on rough terrain.The on-line modification was composed of speed modification,foot lifting-off height modification,step length modification,and identification and avoidance of unsuitable landing terrain.A planner quadruped robot simulator was used to apply the DLP walking method.The correctness of the method was proven by a series of simulations using the Adams and Simulink.
基金the National Key Research and Development Program(2021YFB3502500).
文摘In this paper, we propose an effective full array and sparse array adaptive beamforming scheme that can be applied for multiple desired signals based on the branch-and-bound algorithm. Adaptive beamforming for the multiple desired signals is realized by the improved Capon method. At the same time,the sidelobe constraint is added to reduce the sidelobe level. To reduce the pointing errors of multiple desired signals, the array response phase of the desired signal is firstly optimized by using auxilary variables while keeping the response amplitude unchanged. The whole design is formulated as a convex optimization problem solved by the branch-and-bound algorithm. In addition,the beamformer weight vector is penalized with the modified reweighted l_(1)-norm to achieve sparsity. Theoretical analysis and simulation results show that the proposed algorithm has lower sidelobe level, higher SINR, and less pointing error than the stateof-the-art methods in the case of a single expected signal and multiple desired signals.
基金funded by the American Heart Association Scientist Development Grant SDG12050083National Institutes of Health grant R21 HL102773
文摘Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissue.However,maintaining the viability of a thick tissue structure during tissue growth and maturation is challenging due to lack of adequate vascular perfusion.In a simple tissue model with
文摘英语中有些表示时间的名词,象moment,minute,instant,second,time,day,month,winter,year等等,可以用来引导时间状语从句。如: 1)I recognized him the moment I saw him. 2)She began taming about you the day we met. 句1)中的the moment很象一个连词。
文摘In this paper, solution to the LQ inverse problem has been pre-sented. With the control weight in an LQ optimal control system fixed,the state weighting matrix is parametrized in terms of a set of freevariables and the closed-loop eigenvalues of the control system. Basedon this parametrization, an algorithmic procedure is proposed to deter-mine the state weighting matrix and the free variables by matrixtransformation. Meanwhile, by using the solved free variables, theoptimal feedback gain matrix K can also be obtained without solving thealgebraic Riccati equation.
文摘英语教学的最终目标是培养交际能力,也就是培养学生自由对话的能力。对话是通过话语进行的思想与信息的一种非正式的交流。我们先看一段对话。这段对话是在两个受过教育的美国人之间进行的: A:Ev...Everybody has at least one little superstition,don’t you think? B:I think most people have at least one,
基金Project(2009BSXT022) supported by the Dissertation Innovation Foundation of Central South University, ChinaProject(07JJ4016) supported by Natural Science Foundation of Hunan Province, ChinaProject(U0937604) supported by National Natural Science Foundation of China
文摘To reduce the fuel consumption and emissions and also enhance the molten aluminum quality, a mathematical model with user-developed melting model and burning capacity model, were established according to the features of melting process of regenerative aluminum melting furnaces. Based on validating results by heat balance test for an aluminum melting furnace, CFD （computational fluid dynamics） technique, in association with statistical experimental design were used to optimize the melting process of the aluminum melting furnace. Four important factors influencing the melting time, such as horizontal angle between burners, height-to-radius ratio, natural gas mass flow and air preheated temperature, were identified by PLACKETT-BURMAN design. A steepest descent method was undertaken to determine the optimal regions of these factors. Response surface methodology with BOX-BEHNKEN design was adopted to further investigate the mutual interactions between these variables on RSD （relative standard deviation） of aluminum temperature, RSD of furnace temperature and melting time. Multiple-response optimization by desirability function approach was used to determine the optimum melting process parameters. The results indicate that the interaction between the height-to-radius ratio and horizontal angle between burners affects the response variables significantly. The predicted results show that the minimum RSD of aluminum temperature （12.13%）, RSD of furnace temperature （18.50%） and melting time （3.9 h） could be obtained under the optimum conditions of horizontal angle between burners as 64°, height-to-radius ratio as 0.3, natural gas mass flow as 599 m3/h, and air preheated temperature as 639 ℃. These predicted values were further verified by validation experiments. The excellent correlation between the predicted and experimental values confirms the validity and practicability of this statistical optimum strategy.
文摘There is so much to read today that the ability to read quickly has become an important asset. It is fairly known that the faster readets will have more opportunity and more access to a greater range and quantity of reading material which will give them enhanced pleasure and benifits. Had they not developed their faster reading skills the chances are that they would never have come across many important articles and documents. College students often have a desire and need to be generally informed in some other fields besides their major subjects such as political affairs or cuitur-
文摘There are several web sites for whichinformation is available to the cotton researchcommunity.Most of these sites relate toresources developed or available to the researchcommunity.Few provide bioinformatic tools,which usually relate to the specific data sets andmaterials presented in the database.Just as thebioinformatics area is evolving,the
文摘Green Virtual Enterprise (GVE) is a new contemporar y manufacturing mode, which is to adapt and meet the need of sustainable developme nt of humanity. In, this paper, the concept of Total Green Management is first a dvanced. In this based on the analysis of the Virtual Enterprise (VE) and Total Green Management (TGM), the concept of Green Virtual Enterprise and its architec ture is brought forward.
文摘Goals reasoning and management of pilot is a key issue to monitor pilot's behavior and intention. Traditional modeling methods are based on scenarios or situations, such methods will cause the,covering problem due to redundancy and are incapable of depicting interactions among various goals and plans of pilot. Petri net integrated with belief, desire and intention (BDI) theory (BDI Petri net) is designed to solve this problem. Focusing on the BDI theory, goal states of agent are discussed firstly. Belief, desire and intention are modeled by places and transitions based on the Petri net theory. In order to simplify the network, colored token is introduced to depict various states of belief, and the hierarchy transition is applied to model the intention, together with tokens' flow derrionstrating the interaction among various goals and relationship among belief, desire and intention. A search and rescue mission is used to validate the proposed method and the result indicates that the model can be used to monitor goals and behaviors of pilots.
文摘英语中有些形容词因源于同一动词或名词,拼写有些相似,但发音及意义不同,有时候很容易混淆,往往导致用法及理解方面的错误。现汇集几组举例如下。 1、regrettable与regretful regrettable意为“令人遗憾的,可惜的”,只能用来修饰事物。 例:It is regrettable that they have leftthe city already.很遗憾他们已经离开这个城市。
