The close proximity and the necessity of coordination between multiple high-voltage direct currents(HVDCs)raise the issue of grid partitioning in multi-infeed HVDC systems.A multi-objective partition strategy is propo...The close proximity and the necessity of coordination between multiple high-voltage direct currents(HVDCs)raise the issue of grid partitioning in multi-infeed HVDC systems.A multi-objective partition strategy is proposed in this paper.Several types of relationships to be coordinated and complemented are analyzed and formulated using quantitative indices.According to the graph theory,the HVDC partition is transformed into a graph-cut problem and solved via the spectral clustering algorithm.Finally,the proposed method is validated for a practical multi-HVDC grid,confirming its feasibility and effectiveness.展开更多
As internet services newly emerge with diversity and complexity, great challenges and demands are presented to the Open Flow controlled software defined optical networks(SDON) to achieve better match between services ...As internet services newly emerge with diversity and complexity, great challenges and demands are presented to the Open Flow controlled software defined optical networks(SDON) to achieve better match between services and SDON. With this aim, this paper proposes a naive Echo-State-Network(Naive-ESN) based services awareness algorithm of the software defined optical network, where the naive ESN model adopts the ring topology structure and generates the probability output result to determine the Qo S policy of SDON. Moreover, the Naive-ESN engine is also designed in controller node of SDON to perform services awareness by obtaining service traffic features from data plan, together with some necessary extension of the Open Flow protocol. Test results show that the proposed approach is able to improved services-oriented supporting ability of SDON.展开更多
Streamer discharges in liquids have received lots of attention with respect to their considerable applications invarious disciplines. Much effort has been spent to understand the basis of streamer ignition and propaga...Streamer discharges in liquids have received lots of attention with respect to their considerable applications invarious disciplines. Much effort has been spent to understand the basis of streamer ignition and propagation in dielectricliquids, but a comprehensive mechanism is far from conclusive. In this review, based on an introduction to the streamerphysics and experimentally observed characteristics in various liquids, the authors emphasise on the current status ofstreamer discharge ignition mechanisms and present their understanding for each theory.展开更多
In recent years,small-size,low-weight aerospace propulsion systems have developed rapidly for space exploration,on-orbit scientific instruments and extra space missions,while additional electron emission devices are c...In recent years,small-size,low-weight aerospace propulsion systems have developed rapidly for space exploration,on-orbit scientific instruments and extra space missions,while additional electron emission devices are commonly required in those propulsion systems.Carbon nanotube(CNT)based field emission cathodes exhibit extraordinary field emission properties and are regarded to be an ideal alternative of conventional thermionic or hollow cathodes.In this study,the authors give an overview of present status of researches on CNT-based electron emission cathodes for utilising as neutralisers or electron sources particularly in space electric propulsion systems,the theory and characteristics of CNT are also illustrated.Furthermore,challenges,problems and possible solutions before actual applications of CNT in a space mission are discussed accordingly.展开更多
A MnO_(2)/carbon nanotube(CNT)nanocomposite was synthesised using a simple hydrothermal treatment.The nanocomposite exhibits a CNT core/MnO_(2)porous sheath hierarchy architecture,which makes it promising as an electr...A MnO_(2)/carbon nanotube(CNT)nanocomposite was synthesised using a simple hydrothermal treatment.The nanocomposite exhibits a CNT core/MnO_(2)porous sheath hierarchy architecture,which makes it promising as an electrode material for supercapacitors.An asymmetric supercapacitor based on activated carbon(AC)as anode,MnO_(2)/CNT nanocomposite as cathode and 1M Na_(2)SO_(4)solution as electrolyte was assembled in a Swagelok cell.The full cell exhibits excellent power capability,cycling stability and a high energy density of 23 W h/kg at a power density of 330 W/kg based on the total mass of the active electrode materials.This AC//MnO_(2)/CNT asymmetric supercapacitor is promising for high-power applications due to its high energy density and power density.展开更多
基金supported by the Science and Technology Project of State Grid Corporation of China:“Control Strategy Optimization Technology for Large-Scale Photovoltaic Power Generation on the Sending-end and Receiving-end of DC Power System”(4000-201934198A-0-0-00)
文摘The close proximity and the necessity of coordination between multiple high-voltage direct currents(HVDCs)raise the issue of grid partitioning in multi-infeed HVDC systems.A multi-objective partition strategy is proposed in this paper.Several types of relationships to be coordinated and complemented are analyzed and formulated using quantitative indices.According to the graph theory,the HVDC partition is transformed into a graph-cut problem and solved via the spectral clustering algorithm.Finally,the proposed method is validated for a practical multi-HVDC grid,confirming its feasibility and effectiveness.
基金supported by the Science and Technology Project of State Grid Corporation of China:“Research on the Power-Grid Services Oriented “IP+Optical” Coordination Choreography Technology”.
文摘As internet services newly emerge with diversity and complexity, great challenges and demands are presented to the Open Flow controlled software defined optical networks(SDON) to achieve better match between services and SDON. With this aim, this paper proposes a naive Echo-State-Network(Naive-ESN) based services awareness algorithm of the software defined optical network, where the naive ESN model adopts the ring topology structure and generates the probability output result to determine the Qo S policy of SDON. Moreover, the Naive-ESN engine is also designed in controller node of SDON to perform services awareness by obtaining service traffic features from data plan, together with some necessary extension of the Open Flow protocol. Test results show that the proposed approach is able to improved services-oriented supporting ability of SDON.
基金the PlasmaShape project from the European Union under grant agreement no 316216.
文摘Streamer discharges in liquids have received lots of attention with respect to their considerable applications invarious disciplines. Much effort has been spent to understand the basis of streamer ignition and propagation in dielectricliquids, but a comprehensive mechanism is far from conclusive. In this review, based on an introduction to the streamerphysics and experimentally observed characteristics in various liquids, the authors emphasise on the current status ofstreamer discharge ignition mechanisms and present their understanding for each theory.
基金This work is supported by the National Natural Science Foundation of China(grant no.11802244)the Natural Science Foundation of Shaanxi Province(grant no.2019JQ-033)the Fundamental Research Funds for the Central Universities,China(grant no.1191329723,PY3A083).
文摘In recent years,small-size,low-weight aerospace propulsion systems have developed rapidly for space exploration,on-orbit scientific instruments and extra space missions,while additional electron emission devices are commonly required in those propulsion systems.Carbon nanotube(CNT)based field emission cathodes exhibit extraordinary field emission properties and are regarded to be an ideal alternative of conventional thermionic or hollow cathodes.In this study,the authors give an overview of present status of researches on CNT-based electron emission cathodes for utilising as neutralisers or electron sources particularly in space electric propulsion systems,the theory and characteristics of CNT are also illustrated.Furthermore,challenges,problems and possible solutions before actual applications of CNT in a space mission are discussed accordingly.
基金supported by Nanjing University of Science and Technology through the research grant NUST Research Funding(AB41385 and 2011ZDJH21).
文摘A MnO_(2)/carbon nanotube(CNT)nanocomposite was synthesised using a simple hydrothermal treatment.The nanocomposite exhibits a CNT core/MnO_(2)porous sheath hierarchy architecture,which makes it promising as an electrode material for supercapacitors.An asymmetric supercapacitor based on activated carbon(AC)as anode,MnO_(2)/CNT nanocomposite as cathode and 1M Na_(2)SO_(4)solution as electrolyte was assembled in a Swagelok cell.The full cell exhibits excellent power capability,cycling stability and a high energy density of 23 W h/kg at a power density of 330 W/kg based on the total mass of the active electrode materials.This AC//MnO_(2)/CNT asymmetric supercapacitor is promising for high-power applications due to its high energy density and power density.
