The power and voltage levels of renewable energy resources is growing with the evolution of the power electronics and switching module technologies.For that,the need for the development of a compact and highly efficie...The power and voltage levels of renewable energy resources is growing with the evolution of the power electronics and switching module technologies.For that,the need for the development of a compact and highly efficient solid-state transformer is becoming a critical task in-order to integrate the current AC grid with the new renewable energy systems.The objective of this paper is to present the design,implementation,and testing of a compact multi-port solid-state transformer for microgrid integration applications.The proposed system has a four-port transformer and four converters connected to the ports.The transformer has four windings integrated on a single common core.Thus,it can integrate different renewable energy resources and energy storage systems.Each port has a rated power of 25 kW,and the switching frequency is pushed to 50 k Hz.The ports are chosen to represent a realistic industrial microgrid model consisting of grid,energy storage system,photovoltaic system,and load.The grid port is designed to operate at 4.16 k VAC corresponding to 7.2 kV DC bus voltage,while the other three ports operate at 500 VDC.Moreover,the grid,energy storage and photovoltaic ports are active ports with dual active bridge topologies,while the load port is a passive port with full bridge rectifier one.The proposed design is first validated with simulation results,and then the proposed transformer is implemented and tested.Experimental results show that the designed system is suitable for 4.16 k VAC medium voltage grid integration.展开更多
Solid state transformer(SST)can provide more advanced functionalities compared with conventional transformer,and has great potential in smart grid application.Recently,the SST with medium frequency(MF)isolation link a...Solid state transformer(SST)can provide more advanced functionalities compared with conventional transformer,and has great potential in smart grid application.Recently,the SST with medium frequency(MF)isolation link and magnetic integration feature has been proposed,which can reduce the system volume and thus increase the power density.However,the magnetic integration also introduces strong coupling between the line frequency(LF)and MF variables,which poses a great challenge on modeling and control issues.This paper proposes a modeling and control method for an SST with magnetic integration and mixed-frequency modulation.A mathematical model based on dual d-q references is deduced,and then a cascaded control system is designed according to the model.Parameters of the controller for the variables at one frequency are properly designed to avoid disturbance from the variables at the other frequency.The simulation and experimental results show good decoupling effect and satisfactory dynamics performance of the proposed control system.展开更多
The solid state transformer(SST) can be viewed as an energy router in energy internet. This work presents sliding mode control(SMC) to improve dynamic state and steady state performance of a three-stage(rectifier stag...The solid state transformer(SST) can be viewed as an energy router in energy internet. This work presents sliding mode control(SMC) to improve dynamic state and steady state performance of a three-stage(rectifier stage, isolated stage and inverter stage) SST for energy internet. SMC with three-level hysteresis sliding functions is presented to control the input current of rectifier stage and output voltage of inverter stage to improve the robustness under external disturbance and parametric uncertainties and reduce the switching frequency. A modified feedback linearization technique using isolated stage simplified model is presented to achieve satisfactory regulation of output voltage of the isolated stage. The system is tested for steady state operation, reactive power control, dynamic load change and voltage sag simulations, respectively. The switching model of SST is implemented in Matlab/ Simulink to verify the SST control algorithms.展开更多
The transformation process of an m-DOF free-floating robot from one staticstate to a different static state has m degrees of freedom. The proposed approach of thesetransformations utilizes a series of single-DOF trans...The transformation process of an m-DOF free-floating robot from one staticstate to a different static state has m degrees of freedom. The proposed approach of thesetransformations utilizes a series of single-DOF transformation processes as an alternative to them-DOF transformation process. Two static state transformation processes are studied in detail.First, a single-DOF transformation process is established using a newly defined concept, referred toas transformation planning, and the definite integral of conservation of angular momentum. Second,the governing equation of the single-DOF transformation process is established using the dynamicequations of motion of the robot. This allows the joint torques to be computed to effect the statetransformation. Finally, an extension of the single-DOF transformation process is proposed to extendthe application of this proposed transformation methodology to create a transformation net whichallows the reconfiguration of a robot from one state to many other possible states.展开更多
We have succeeded in causing reversible polymorphic transformation of 2,2':6',2"-terpyridine (terpy). By contacting a template terpy crystal with the target crystal, reversible orthorhombic-to-monoclinic ...We have succeeded in causing reversible polymorphic transformation of 2,2':6',2"-terpyridine (terpy). By contacting a template terpy crystal with the target crystal, reversible orthorhombic-to-monoclinic transformation occurred directly without via melting state. The transformation process is successfully visualized and it is found that the template crystal influences the transition temperature itself.展开更多
This paper presents a high-power-density solid-state transformer(SST)designed for 25 kV alternative current railway applications,delivering a 3 kV direct current output to traction inverters.The SST is composed of sub...This paper presents a high-power-density solid-state transformer(SST)designed for 25 kV alternative current railway applications,delivering a 3 kV direct current output to traction inverters.The SST is composed of sub-modules with the adoption of 1.7 kV insulated gate bipolar transistor and SiC metal oxide field effect transistor(MOSFET)in an input-series-output-series structure,providing higher power density than conventional topologies that rely on high-voltage switches(>1.7 kV).Because these high-voltage SiC MOSFETs are still expensive and not fully commercialised,the proposed approach offers a more cost-effective alternative.A total of 42 converter cells ensure a highly modular and scalable design,with precise synchronisation and high-speed control achieved through an EtherCAT-based communication network.Additionally,a distributed control algorithm is introduced,mitigating excessive dependence on the communication link for module-level operations.The effectiveness of the entire system-including the design and control schemes-has been experimentally verified,ranging from individual converter cells to a reduced SST prototype of up to three sub-modules.These results confirm the feasibility and advantages of the proposed SST in terms of power density,cost efficiency and reliability for railway traction applications.展开更多
锂电池健康状态(state of health, SOH)可表征锂电池的老化状态。为准确评估SOH,首先,提取充电阶段的电流、电压、IC曲线中的6个特征,为了提高输入特征的质量,采用核主成分分析(kernel principal component analysis, KPCA)结合Spearma...锂电池健康状态(state of health, SOH)可表征锂电池的老化状态。为准确评估SOH,首先,提取充电阶段的电流、电压、IC曲线中的6个特征,为了提高输入特征的质量,采用核主成分分析(kernel principal component analysis, KPCA)结合Spearman相关性分析,消除多维特征的冗余性获取输入特征的关键信息。其次,为了降低模型复杂度,将全连接层代替Transformer解码器,并利用牛顿-拉夫逊优化算法(Newton-Raphson-based optimization algorithm, NRBO)对模型的超参数寻优,提高预测精度。最后,利用公开数据集不同训练比例划分验证方法的有效性,并采用不同电池交叉验证与灰狼优化算法(gray wolf optimization algorithm, GWO)和鲸鱼优化算法(whale optimization algorithm, WOA)进行比较,结果表明:所提方法在精度和计算耗时方面均优于其他2种算法。展开更多
The paper discusses efforts of finding a simple and transparent method to analyze business processes and developing its management system architecture. By introducing ontology and its state, the approach tried to find...The paper discusses efforts of finding a simple and transparent method to analyze business processes and developing its management system architecture. By introducing ontology and its state, the approach tried to find a unified representation and a flexible choreography of business processes. The main idea of the paper is the transformation of ontology＇s states, which are the most important scenarios of enterprises. The business activity composition, that is, case composition based on an AI technique, Case Based Reason （CBR）, which is to solve new problems by retrieving solutions to previous problems, and then store the modified solution. The main interest in CBR relies on that it allows a system to avoid past failures and exploit past successes.展开更多
To solve the problems of updating sub-secrets or secrets as well as adding or deleting agents in the quantum secret sharing protocol, we propose a two-particle transform of Bell states, and consequently present a nove...To solve the problems of updating sub-secrets or secrets as well as adding or deleting agents in the quantum secret sharing protocol, we propose a two-particle transform of Bell states, and consequently present a novel dynamic quantum secret sharing protocol. The new protocol can not only resist some typical attacks, but also be more efficient than the existing protocols. Furthermore, we take advantage of the protocol to establish the dynamic secret sharing of a quantum state protocol for two-particle maximum entangled states.展开更多
The phase transformation activation energy of the Cu61.13Zn33.94A14.93 alloys, which were treated at 4 GPa and 700 ℃ for 15 minutes, was calculated by means of differential scanning calorimetry curves obtained at var...The phase transformation activation energy of the Cu61.13Zn33.94A14.93 alloys, which were treated at 4 GPa and 700 ℃ for 15 minutes, was calculated by means of differential scanning calorimetry curves obtained at various heating and cooling rates. Then, the effects of high-pressure heat treatments on the solid-state phase transformation and the microstructures of Cu61.13Zn33.94A14.93 alloys were investigated. The results show that high-pressure heat treatments can refine the grains and can change the preferred orientation from （111） to （200） of α phase. Compared with the as-cast alloy, the sample with high-pressure heat treatment has finer grains, lower β＇→β and/β→β＇ transformation temperature and activation energy. Furthermore, we found that high cooling rate favours the formation of fine needle-like α phase in the range of 5-20℃/min.展开更多
视频字幕生成(Video Captioning)旨在用自然语言描述视频中的内容,在人机交互、辅助视障人士、体育视频解说等领域具有广泛的应用前景。然而视频中复杂的时空内容变化增加了视频字幕生成的难度,之前的方法通过提取时空特征、先验信息等...视频字幕生成(Video Captioning)旨在用自然语言描述视频中的内容,在人机交互、辅助视障人士、体育视频解说等领域具有广泛的应用前景。然而视频中复杂的时空内容变化增加了视频字幕生成的难度,之前的方法通过提取时空特征、先验信息等方式提高生成字幕的质量,但在时空联合建模方面仍存在不足,可能导致视觉信息提取不充分,影响字幕生成结果。为了解决这个问题,本文提出一种新颖的时空增强的状态空间模型和Transformer(SpatioTemporal-enhanced State space model and Transformer,ST2)模型,通过引入最近流行的具有全局感受野和线性的计算复杂度的Mamba(一种状态空间模型),增强时空联合建模能力。首先,通过将Mamba与Transformer并行结合,提出空间增强的状态空间模型(State Space Model,SSM)和Transformer(Spatial enHanced State space model and Transformer module,SH-ST),克服了卷积的感受野问题并降低计算复杂度,同时增强模型提取空间信息的能力。然后为了增强时间建模,我们利用Mamba的时间扫描特性,并结合Transformer的全局建模能力,提出时间增强的SSM和Transformer(Temporal enHanced State space model and Transformer module,TH-ST)。具体地,我们对SH-ST产生的特征进行重排序,从而使Mamba以交叉扫描的方式增强重排序后特征的时间关系,最后用Transformer进一步增强时间建模能力。实验结果表明,我们ST2模型中SH-ST和TH-ST结构设计的有效性,且在广泛使用的视频字幕生成数据集MSVD和MSR-VTT上取得了具有竞争力的结果。具体的,我们的方法分别在MSVD和MSR-VTT数据集上的绝对CIDEr分数超过最先进的结果6.9%和2.6%,在MSVD上的绝对CIDEr分数超过了基线结果4.9%。展开更多
Failure mechanisms of power transformers are complex and uncertain; it is difficult to determine index weights of insulation state. Therefore, it is a challenge to acquire an accurate assessment of insulation state of...Failure mechanisms of power transformers are complex and uncertain; it is difficult to determine index weights of insulation state. Therefore, it is a challenge to acquire an accurate assessment of insulation state of power transformers. In this paper, an assessing strategy for transformer insulation is proposed base on part-division of transformer and a comprehensive weight determination method. An index system of transformer is established on the basis of part-division of transformer. Each index’s weight is consisted of two parts, the constant weight and the variable weight, which are determined by improved analytic hierarchy process (AHP) and entropy method respectively. Af- ter categorizing insulation state into four levels and standardizing assessing indexes, a Cauchy membership function is forged, and a fuzzy algorithm is employed to simulate the uncertainty of the insulation state. Finally, a confidence criterion is employed to perform part-division based condition assessment of transformer. Case studies reveal that the proposed assessing strategy method is effective, convenient, and practical; with the new strategy, potential failures of transformers can be forecasted and insulation state of transformer parts can also be as- sessed. Furthermore, the assessing results can be used to guide condition-based maintenance.展开更多
We present a scheme for probabilistic transformation of special quantum states assisted by auxiliary qubits.In our scheme,if quantum states can be rewritten in a particular form,it is possible to transform such states...We present a scheme for probabilistic transformation of special quantum states assisted by auxiliary qubits.In our scheme,if quantum states can be rewritten in a particular form,it is possible to transform such states into other states using lowerdimensional unitary operations that can be more easily realized in physical experiments.Furthermore,as an important application,we propose a generalized scheme that helps construct faithful quantum channels via various probabilistic channels when considering the existence of nonmaximally-entangled states.展开更多
基金supported by the National Science Foundation under Grant No.1650470,GRAPES I/UCRC program。
文摘The power and voltage levels of renewable energy resources is growing with the evolution of the power electronics and switching module technologies.For that,the need for the development of a compact and highly efficient solid-state transformer is becoming a critical task in-order to integrate the current AC grid with the new renewable energy systems.The objective of this paper is to present the design,implementation,and testing of a compact multi-port solid-state transformer for microgrid integration applications.The proposed system has a four-port transformer and four converters connected to the ports.The transformer has four windings integrated on a single common core.Thus,it can integrate different renewable energy resources and energy storage systems.Each port has a rated power of 25 kW,and the switching frequency is pushed to 50 k Hz.The ports are chosen to represent a realistic industrial microgrid model consisting of grid,energy storage system,photovoltaic system,and load.The grid port is designed to operate at 4.16 k VAC corresponding to 7.2 kV DC bus voltage,while the other three ports operate at 500 VDC.Moreover,the grid,energy storage and photovoltaic ports are active ports with dual active bridge topologies,while the load port is a passive port with full bridge rectifier one.The proposed design is first validated with simulation results,and then the proposed transformer is implemented and tested.Experimental results show that the designed system is suitable for 4.16 k VAC medium voltage grid integration.
基金the National Natural Science Foundation of China under Grant 51777085.
文摘Solid state transformer(SST)can provide more advanced functionalities compared with conventional transformer,and has great potential in smart grid application.Recently,the SST with medium frequency(MF)isolation link and magnetic integration feature has been proposed,which can reduce the system volume and thus increase the power density.However,the magnetic integration also introduces strong coupling between the line frequency(LF)and MF variables,which poses a great challenge on modeling and control issues.This paper proposes a modeling and control method for an SST with magnetic integration and mixed-frequency modulation.A mathematical model based on dual d-q references is deduced,and then a cascaded control system is designed according to the model.Parameters of the controller for the variables at one frequency are properly designed to avoid disturbance from the variables at the other frequency.The simulation and experimental results show good decoupling effect and satisfactory dynamics performance of the proposed control system.
基金Projects(61403404,71571187)supported by the National Natural Science Foundation of China
文摘The solid state transformer(SST) can be viewed as an energy router in energy internet. This work presents sliding mode control(SMC) to improve dynamic state and steady state performance of a three-stage(rectifier stage, isolated stage and inverter stage) SST for energy internet. SMC with three-level hysteresis sliding functions is presented to control the input current of rectifier stage and output voltage of inverter stage to improve the robustness under external disturbance and parametric uncertainties and reduce the switching frequency. A modified feedback linearization technique using isolated stage simplified model is presented to achieve satisfactory regulation of output voltage of the isolated stage. The system is tested for steady state operation, reactive power control, dynamic load change and voltage sag simulations, respectively. The switching model of SST is implemented in Matlab/ Simulink to verify the SST control algorithms.
文摘The transformation process of an m-DOF free-floating robot from one staticstate to a different static state has m degrees of freedom. The proposed approach of thesetransformations utilizes a series of single-DOF transformation processes as an alternative to them-DOF transformation process. Two static state transformation processes are studied in detail.First, a single-DOF transformation process is established using a newly defined concept, referred toas transformation planning, and the definite integral of conservation of angular momentum. Second,the governing equation of the single-DOF transformation process is established using the dynamicequations of motion of the robot. This allows the joint torques to be computed to effect the statetransformation. Finally, an extension of the single-DOF transformation process is proposed to extendthe application of this proposed transformation methodology to create a transformation net whichallows the reconfiguration of a robot from one state to many other possible states.
文摘We have succeeded in causing reversible polymorphic transformation of 2,2':6',2"-terpyridine (terpy). By contacting a template terpy crystal with the target crystal, reversible orthorhombic-to-monoclinic transformation occurred directly without via melting state. The transformation process is successfully visualized and it is found that the template crystal influences the transition temperature itself.
基金Korea Institute of Energy Technology Evaluation and Planning funded by the Korea Government,Grant/Award Number:20224000000160Korea Agency for Infrastructure Technology Advancement,Grant/Award Number:RS 2021-KA163337。
文摘This paper presents a high-power-density solid-state transformer(SST)designed for 25 kV alternative current railway applications,delivering a 3 kV direct current output to traction inverters.The SST is composed of sub-modules with the adoption of 1.7 kV insulated gate bipolar transistor and SiC metal oxide field effect transistor(MOSFET)in an input-series-output-series structure,providing higher power density than conventional topologies that rely on high-voltage switches(>1.7 kV).Because these high-voltage SiC MOSFETs are still expensive and not fully commercialised,the proposed approach offers a more cost-effective alternative.A total of 42 converter cells ensure a highly modular and scalable design,with precise synchronisation and high-speed control achieved through an EtherCAT-based communication network.Additionally,a distributed control algorithm is introduced,mitigating excessive dependence on the communication link for module-level operations.The effectiveness of the entire system-including the design and control schemes-has been experimentally verified,ranging from individual converter cells to a reduced SST prototype of up to three sub-modules.These results confirm the feasibility and advantages of the proposed SST in terms of power density,cost efficiency and reliability for railway traction applications.
基金Supported bythe Shandong Province Great ScienceTechnology National Projects (004GG4201022)
文摘The paper discusses efforts of finding a simple and transparent method to analyze business processes and developing its management system architecture. By introducing ontology and its state, the approach tried to find a unified representation and a flexible choreography of business processes. The main idea of the paper is the transformation of ontology＇s states, which are the most important scenarios of enterprises. The business activity composition, that is, case composition based on an AI technique, Case Based Reason （CBR）, which is to solve new problems by retrieving solutions to previous problems, and then store the modified solution. The main interest in CBR relies on that it allows a system to avoid past failures and exploit past successes.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB338002)
文摘To solve the problems of updating sub-secrets or secrets as well as adding or deleting agents in the quantum secret sharing protocol, we propose a two-particle transform of Bell states, and consequently present a novel dynamic quantum secret sharing protocol. The new protocol can not only resist some typical attacks, but also be more efficient than the existing protocols. Furthermore, we take advantage of the protocol to establish the dynamic secret sharing of a quantum state protocol for two-particle maximum entangled states.
文摘The phase transformation activation energy of the Cu61.13Zn33.94A14.93 alloys, which were treated at 4 GPa and 700 ℃ for 15 minutes, was calculated by means of differential scanning calorimetry curves obtained at various heating and cooling rates. Then, the effects of high-pressure heat treatments on the solid-state phase transformation and the microstructures of Cu61.13Zn33.94A14.93 alloys were investigated. The results show that high-pressure heat treatments can refine the grains and can change the preferred orientation from （111） to （200） of α phase. Compared with the as-cast alloy, the sample with high-pressure heat treatment has finer grains, lower β＇→β and/β→β＇ transformation temperature and activation energy. Furthermore, we found that high cooling rate favours the formation of fine needle-like α phase in the range of 5-20℃/min.
文摘视频字幕生成(Video Captioning)旨在用自然语言描述视频中的内容,在人机交互、辅助视障人士、体育视频解说等领域具有广泛的应用前景。然而视频中复杂的时空内容变化增加了视频字幕生成的难度,之前的方法通过提取时空特征、先验信息等方式提高生成字幕的质量,但在时空联合建模方面仍存在不足,可能导致视觉信息提取不充分,影响字幕生成结果。为了解决这个问题,本文提出一种新颖的时空增强的状态空间模型和Transformer(SpatioTemporal-enhanced State space model and Transformer,ST2)模型,通过引入最近流行的具有全局感受野和线性的计算复杂度的Mamba(一种状态空间模型),增强时空联合建模能力。首先,通过将Mamba与Transformer并行结合,提出空间增强的状态空间模型(State Space Model,SSM)和Transformer(Spatial enHanced State space model and Transformer module,SH-ST),克服了卷积的感受野问题并降低计算复杂度,同时增强模型提取空间信息的能力。然后为了增强时间建模,我们利用Mamba的时间扫描特性,并结合Transformer的全局建模能力,提出时间增强的SSM和Transformer(Temporal enHanced State space model and Transformer module,TH-ST)。具体地,我们对SH-ST产生的特征进行重排序,从而使Mamba以交叉扫描的方式增强重排序后特征的时间关系,最后用Transformer进一步增强时间建模能力。实验结果表明,我们ST2模型中SH-ST和TH-ST结构设计的有效性,且在广泛使用的视频字幕生成数据集MSVD和MSR-VTT上取得了具有竞争力的结果。具体的,我们的方法分别在MSVD和MSR-VTT数据集上的绝对CIDEr分数超过最先进的结果6.9%和2.6%,在MSVD上的绝对CIDEr分数超过了基线结果4.9%。
基金Project supported by Fund for Innovative Research Groups of China (51021005)Fundamental Research Fund for the Central Universities of China(CDJRC10150004)
文摘Failure mechanisms of power transformers are complex and uncertain; it is difficult to determine index weights of insulation state. Therefore, it is a challenge to acquire an accurate assessment of insulation state of power transformers. In this paper, an assessing strategy for transformer insulation is proposed base on part-division of transformer and a comprehensive weight determination method. An index system of transformer is established on the basis of part-division of transformer. Each index’s weight is consisted of two parts, the constant weight and the variable weight, which are determined by improved analytic hierarchy process (AHP) and entropy method respectively. Af- ter categorizing insulation state into four levels and standardizing assessing indexes, a Cauchy membership function is forged, and a fuzzy algorithm is employed to simulate the uncertainty of the insulation state. Finally, a confidence criterion is employed to perform part-division based condition assessment of transformer. Case studies reveal that the proposed assessing strategy method is effective, convenient, and practical; with the new strategy, potential failures of transformers can be forecasted and insulation state of transformer parts can also be as- sessed. Furthermore, the assessing results can be used to guide condition-based maintenance.
基金supported by the National Natural Science Foundation of China(61104002,60904034and61071214)the Natural Science Foundation of Jiangsu Province(BK2011283and BK2011377)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(10KJB510024)
文摘We present a scheme for probabilistic transformation of special quantum states assisted by auxiliary qubits.In our scheme,if quantum states can be rewritten in a particular form,it is possible to transform such states into other states using lowerdimensional unitary operations that can be more easily realized in physical experiments.Furthermore,as an important application,we propose a generalized scheme that helps construct faithful quantum channels via various probabilistic channels when considering the existence of nonmaximally-entangled states.
