The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation b...The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation behavior of Cu-containing precipitates, and the resultant mechanical properties of the composites were systematically investigated. The results showed that the increase of Cu content can not only increase the number and size of Cu-containing precipitate generated during the composite fabrication processes, but also promote the interfacial reaction between CNTs and Al matrix, leading to the intensified conversion of CNTs into Al_(4)C_(3). As a result, the composite containing 1 wt.% Cu possesses the highest strength, elastic modulus and hardness among all composites, due to the maintenance of the original structure of CNTs. Moreover, the increase of Cu content can change the dominant strengthening mechanisms for the enhanced strength of the fabricated composites.展开更多
To study the influence of the Soret and Dufour effects on the reactive characteristics of a porous packed bed with endothermic reactions and forced convection, a two-dimensional mathematical model considering the cros...To study the influence of the Soret and Dufour effects on the reactive characteristics of a porous packed bed with endothermic reactions and forced convection, a two-dimensional mathematical model considering the cross-diffusion effects was developed in accordance with the thermodynamics of irreversible processes and the local thermal non-equilibrium model. The simulation results were validated by comparing with experimental data. The influence of the Soret and Dufour effects on the heat transfer, mass transfer and endothermic chemical reaction in the non-thermal equilibrium packed bed is discussed. It was found that when the Peclet number reaches 1865, the maximum relative error of the concentration of gas product induced by the Soret effect is 34.7% and that of the solid fractional conversion caused by the Dufour effect is 10.8% at reaction time 160 s and initial temperature 1473 K. The differences induced by the Soret and Dufour effects are demonstrated numerically to increase gradually with the initial temperature of feeding gas and the Peclet number.展开更多
Single gimbal control moment gyroscope(SGCMG)with high precision and fast response is an important attitude control system for high precision docking,rapid maneuvering navigation and guidance system in the aerospace f...Single gimbal control moment gyroscope(SGCMG)with high precision and fast response is an important attitude control system for high precision docking,rapid maneuvering navigation and guidance system in the aerospace field.In this paper,considering the influence of multi-source disturbance,a data-based feedback relearning(FR)algorithm is designed for the robust control of SGCMG gimbal servo system.Based on adaptive dynamic programming and least-square principle,the FR algorithm is used to obtain the servo control strategy by collecting the online operation data of SGCMG system.This is a model-free learning strategy in which no prior knowledge of the SGCMG model is required.Then,combining the reinforcement learning mechanism,the servo control strategy is interacted with system dynamic of SGCMG.The adaptive evaluation and improvement of servo control strategy against the multi-source disturbance are realized.Meanwhile,a data redistribution method based on experience replay is designed to reduce data correlation to improve algorithm stability and data utilization efficiency.Finally,by comparing with other methods on the simulation model of SGCMG,the effectiveness of the proposed servo control strategy is verified.展开更多
As an incentive to innovation, intellectual property （IP） should be protected by law. However, as it is a key factor in market competition, it should also be subject to competition law. In most jurisdictions, restri...As an incentive to innovation, intellectual property （IP） should be protected by law. However, as it is a key factor in market competition, it should also be subject to competition law. In most jurisdictions, restriction of competition related to IP rights is not a black and white question, and such rights are challenged only when the IP owners hold market power and when protection of their fights has a serious and unreasonable effect on competition. In assessing IP-related restriction of competition, we need to analyze several elements： we have to define the relevant markets, identify the parties concerned, determine their market share, assess the anti-competitive effects of the controls, etc.. China＇s existing legislation is not adequate to solve problems arising from IP-related restriction of competition. Nevertheless, the process of China＇s legislation on this issue shows clearly that the misuse of IP rights for the purpose of excluding or significantly restricting competition is not justifiable under competition law.展开更多
A resource-based economy is an economic system driven by the exploitation of mineral resources and dominated by the energy, mineral and other resource sectors. In resource- rich areas, there is often an investment bia...A resource-based economy is an economic system driven by the exploitation of mineral resources and dominated by the energy, mineral and other resource sectors. In resource- rich areas, there is often an investment bias toward the resource sector because of the existence of a threshold for investment in human capital in the manufacturing sector. Once the resource sector is dominant, it has a particular atwaction effect on the economic factors; its expansion and spread have a viscosity effect on industry families;, and the sunk costs and path dependence that emerge as industrialization evolves have a lock-in effect on the role of resources. This may give rise to development path dependence and the trap of resource advantage, resulting in a self-strengthening mechanism in resource-based economies. The key to escaping this trap is to break down the resource sector＇s original self-perpetuating mechanism and path dependence, introduce learning and innovation, adjust mechanisms far the distribution of resource benefits and realize industry coordination and transformational economic development.展开更多
基金The financial supports from the National Natural Science Foundation of China (Nos. 52004101 and 52071269)the Chinese Postdoctoral Science Foundation (No. 2020T130246)+2 种基金the Fund of the State Key Laboratory of Solidification Processing in NWPU, China (No. SKLSP202121)the Guangdong Basic and Applied Basic Research Foundation, China (No. 2020A1515110621)the Fundamental Research Funds for the Central Universities, China (No. 11620345)。
文摘The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation behavior of Cu-containing precipitates, and the resultant mechanical properties of the composites were systematically investigated. The results showed that the increase of Cu content can not only increase the number and size of Cu-containing precipitate generated during the composite fabrication processes, but also promote the interfacial reaction between CNTs and Al matrix, leading to the intensified conversion of CNTs into Al_(4)C_(3). As a result, the composite containing 1 wt.% Cu possesses the highest strength, elastic modulus and hardness among all composites, due to the maintenance of the original structure of CNTs. Moreover, the increase of Cu content can change the dominant strengthening mechanisms for the enhanced strength of the fabricated composites.
基金Supported by the National Natural Science Foundation of China （51004071, 51164015） Special Project for High-end CNC Machine Tools and Basic Manufacturing Equipment of China （2012ZX04007-021） Liaoning Province College Excellent Talents Fund Project （LJQ2013012）
文摘To study the influence of the Soret and Dufour effects on the reactive characteristics of a porous packed bed with endothermic reactions and forced convection, a two-dimensional mathematical model considering the cross-diffusion effects was developed in accordance with the thermodynamics of irreversible processes and the local thermal non-equilibrium model. The simulation results were validated by comparing with experimental data. The influence of the Soret and Dufour effects on the heat transfer, mass transfer and endothermic chemical reaction in the non-thermal equilibrium packed bed is discussed. It was found that when the Peclet number reaches 1865, the maximum relative error of the concentration of gas product induced by the Soret effect is 34.7% and that of the solid fractional conversion caused by the Dufour effect is 10.8% at reaction time 160 s and initial temperature 1473 K. The differences induced by the Soret and Dufour effects are demonstrated numerically to increase gradually with the initial temperature of feeding gas and the Peclet number.
基金This work was supported by the National Natural Science Foundation of China(No.62022061)Tianjin Natural Science Foundation(No.20JCYBJC00880)Beijing Key Laboratory Open Fund of Long-Life Technology of Precise Rotation and Transmission Mechanisms.
文摘Single gimbal control moment gyroscope(SGCMG)with high precision and fast response is an important attitude control system for high precision docking,rapid maneuvering navigation and guidance system in the aerospace field.In this paper,considering the influence of multi-source disturbance,a data-based feedback relearning(FR)algorithm is designed for the robust control of SGCMG gimbal servo system.Based on adaptive dynamic programming and least-square principle,the FR algorithm is used to obtain the servo control strategy by collecting the online operation data of SGCMG system.This is a model-free learning strategy in which no prior knowledge of the SGCMG model is required.Then,combining the reinforcement learning mechanism,the servo control strategy is interacted with system dynamic of SGCMG.The adaptive evaluation and improvement of servo control strategy against the multi-source disturbance are realized.Meanwhile,a data redistribution method based on experience replay is designed to reduce data correlation to improve algorithm stability and data utilization efficiency.Finally,by comparing with other methods on the simulation model of SGCMG,the effectiveness of the proposed servo control strategy is verified.
基金This article forms part of the 2006 national major project of the Ministry of Justice on the rule of law and judicial theory,"Market Economy and Anti-monopoly Law:From the Perspective of Intellectual Property"(06SFB 1015).
文摘As an incentive to innovation, intellectual property （IP） should be protected by law. However, as it is a key factor in market competition, it should also be subject to competition law. In most jurisdictions, restriction of competition related to IP rights is not a black and white question, and such rights are challenged only when the IP owners hold market power and when protection of their fights has a serious and unreasonable effect on competition. In assessing IP-related restriction of competition, we need to analyze several elements： we have to define the relevant markets, identify the parties concerned, determine their market share, assess the anti-competitive effects of the controls, etc.. China＇s existing legislation is not adequate to solve problems arising from IP-related restriction of competition. Nevertheless, the process of China＇s legislation on this issue shows clearly that the misuse of IP rights for the purpose of excluding or significantly restricting competition is not justifiable under competition law.
文摘A resource-based economy is an economic system driven by the exploitation of mineral resources and dominated by the energy, mineral and other resource sectors. In resource- rich areas, there is often an investment bias toward the resource sector because of the existence of a threshold for investment in human capital in the manufacturing sector. Once the resource sector is dominant, it has a particular atwaction effect on the economic factors; its expansion and spread have a viscosity effect on industry families;, and the sunk costs and path dependence that emerge as industrialization evolves have a lock-in effect on the role of resources. This may give rise to development path dependence and the trap of resource advantage, resulting in a self-strengthening mechanism in resource-based economies. The key to escaping this trap is to break down the resource sector＇s original self-perpetuating mechanism and path dependence, introduce learning and innovation, adjust mechanisms far the distribution of resource benefits and realize industry coordination and transformational economic development.
