An alternating magnetic field(AMF)was introduced into the narrow gap laser-arc hybrid welding process for 2205 duplex stainless steel thick plates.The corrosion performance of the welded joints was evaluated through e...An alternating magnetic field(AMF)was introduced into the narrow gap laser-arc hybrid welding process for 2205 duplex stainless steel thick plates.The corrosion performance of the welded joints was evaluated through electrochemical studies.The results revealed that joints welded with the application of AMF had a lower corrosion current density compared to those welded without an external AMF.Additionally,these joints showed higher pitting potential and polarization resistance.Microscopic electrochemical analysis indicated that joints subjected to AMF exhibited minimal cathodic current in simulated seawater,with only slight fluctuations in the anodic current peak.Overall,the corrosion levels on the joint surfaces were relatively low.After 4 h of immersion in the corrosive medium,the average impedance of joints exposed to AMF increased by 60.7%compared to those not influenced by a magnetic field.These findings suggest that applying AMF during the narrow gap laser-arc hybrid welding process can significantly improve the corrosion resistance of duplex stainless steel welded joints,reducing their susceptibility to stress corrosion in seawater-like environments.展开更多
Divergence of gene expression and alter native splicing is a crucial driving force in the evolution of species;to date, however the molecular mechanism remains unclear. Hybrids of closely related species provide a sui...Divergence of gene expression and alter native splicing is a crucial driving force in the evolution of species;to date, however the molecular mechanism remains unclear. Hybrids of closely related species provide a suitable model to analyze allele-specific expressi on (ASE) and allele-specific alter native splicing (ASS). Analysis of ASE and ASS can uncover the differences in cis-regulatory elements between closely related species, while eliminating interferenee of trans-regulatory elements. Here, we provide a detailed characterization of ASE and ASS from 19 and 10 transcriptome datasets across five tissues from reciprocal-cross hybrids of horsex don key (mule/hi nny) and cattlexyak (dzo), respectively. Results showed that 4.8%-8.7% and 10.8%-16.7% of genes exhibited ASE and ASS, respectively. Notably, IncRNAs and pseudogenes were more likely to show ASE than protein-coding genes. In addition, genes showing ASE and ASS in mule/hinny were found to be involved in the regulation of muscle strength, whereas those of dzo were involved in high-altitude adaptati on. In con clusi on, our study dem on strated that explorati on of genes showing ASE and ASS in hybrids of closely related species is feasible for species evolution research.展开更多
In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a c...In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a conductive, stable plasma channel for arcs. Plasma radiation strengthened especially in the center of the arc after hybrid. High temperature plasma erupting from keyhole provides an upward reacting force which can prevent droplet from transfer. The charged particles consisted in high temperature plasma reduce the voltage that maintains arc ignition or burning. The results show that laser can influence the arc shape, prevent droplet transfer, reduce resistivity and stabilize arcs.展开更多
Interconnection planning involving bi-directional converters(BdCs)is crucial for enhancing the reliability and robustness of hybrid alternating current(AC)/direct current(DC)microgrid clusters with high penetrations o...Interconnection planning involving bi-directional converters(BdCs)is crucial for enhancing the reliability and robustness of hybrid alternating current(AC)/direct current(DC)microgrid clusters with high penetrations of renewable energy resources(RESs).However,challenges such as the non-convex nature of BdC efficiency and renewable energy uncertainty complicate the planning process.To address these issues,this paper proposes a tri-level BdC-based planning framework that incorporates dynamic BdC efficiency and a data-correlated uncertainty set(DcUS)derived from historical data patterns.The proposed framework employs a least-squares approximation to linearize BdC efficiency and constructs the DcUS to balance computational efficiency and solution robustness.Additionally,a fully parallel column and constraint generation algorithm is developed to solve the model efficiently.Numerical simulations on a practical hybrid AC/DC microgrid system demonstrate that the proposed method reduces interconnection costs by up to 21.8%compared to conventional uncertainty sets while ensuring robust operation under all considered scenarios.These results highlight the computational efficiency,robustness,and practicality of the proposed approach,making it a promising solution for modern power systems.展开更多
Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output system...Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.展开更多
The central aim of this paper is to provide an upto-date snapshot of hybrid and hydrogen technology-related developments and activities in the North American heavy haul railway setting,placed in the context of the tra...The central aim of this paper is to provide an upto-date snapshot of hybrid and hydrogen technology-related developments and activities in the North American heavy haul railway setting,placed in the context of the transportation industry more broadly.An overview of relevant alternative propulsion technologies is provided,including a discussion of applicability to the transportation sector in general and heavy haul freight rail specifically.This is followed by a discussion of current developments and research in alternative and blended fuels,discussed again in both general and specific settings.Key factors and technical considerations for heavy haul applications are reviewed,followed by a discussion of non-technical and human factors that motivate a move toward clean energy in North American Heavy Haul systems.Finally,current project activities are described to provide a clear understanding of both the status and trajectory of hybrid and hydrogen technologies in the established context.展开更多
Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink...Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions.展开更多
A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems. The near body region is discretized by using the body-fitted structured grids, while the remaining computational dom...A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems. The near body region is discretized by using the body-fitted structured grids, while the remaining computational domain is tessellated with the generated Cartesian grids. As the body moves, the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication. By using the alternating digital tree （ADT） algorithm, the computational time of hole-cutting and identification of donor cells can be reduced significantly. A compressible solver for unsteady flow problems is developed. A cell-centered, second-order accurate finite volume method is employed in spatial discreti- zation and an implicit dual-time stepping low-upper symmetric Gauss-Seidei （LU-SGS） approach is employed in temporal discretization. Geometry-based adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weigh- ting interpolation formula. Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method. Then, a 2-D store separation problem is simulated. The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.展开更多
Recently global warming and the depletion of fuel resources have accelerated researchers’ efforts to produce more efficient and clean alternatives. This research presents a comprehensive review of the different adjus...Recently global warming and the depletion of fuel resources have accelerated researchers’ efforts to produce more efficient and clean alternatives. This research presents a comprehensive review of the different adjustments/con figurations of electric vehicles (EVs) and hybrid electric vehicles (HEVs), traction motors for power systems, and wireless speed control of traction drive. Electronic installation of technology can reduce pollution efficiently and effectively. The efficient operation has always been one of the most common investigators’ objectives in the automotive industry and academic areas. There are several renewable energy resources for hybrid vehicles that will replace depleted gasoline worldwide. The purpose of this paper is the development of more efficient pure EVs, HEVs, and fuel cell electric vehicles (FCEV) present both a challenge and a definite solution to current mobility issues. Fuel consumption in cars is a concern due to the harmful effects on the environment. Among other battery sources, fuel cells (FC), super capacitors (SC), and photovoltaic cells are studied for vehicle application. A combination of these renewable energy sources can be used for hybrid electric vehicles (HEV) in the next generation of transportation. With the significant progress of automobile technology, the hybrid electric vehicle has already become the main achievement of transportation electrification due to its excellent fuel-saving performance.展开更多
针对多输入多输出(multiple-input multiple-output,MIMO)雷达通信一体化(dual-function radarcommunication,DFRC)系统性能对信道状态信息(channel state information,CSI)精度敏感的问题,构建了非完美CSI条件下的模数混合波束形成设...针对多输入多输出(multiple-input multiple-output,MIMO)雷达通信一体化(dual-function radarcommunication,DFRC)系统性能对信道状态信息(channel state information,CSI)精度敏感的问题,构建了非完美CSI条件下的模数混合波束形成设计模型,提出了一种鲁棒的混合波束形成器优化方法。利用CSI误差的先验统计信息,在满足通信中断概率约束的同时最小化雷达方向图加权均方误差,以得到期望的发射数字和模拟波束形成矩阵。所提出的非凸优化问题首先利用坎泰利(Cantelli)不等式进行近似处理,再利用交替方向乘子法(alternating direction method of multipliers,ADMM)求解。仿真实验对比了多种算法之间的性能差异,验证了所提出的MIMO-DFRC混合波束形成设计方法具有高效性和鲁棒性。展开更多
基金supported by the National Natural Science Foundation of China(No.52265054)the Inner Mongolia Autonomous Region Natural Science Foundation Project(No.2022ZD03)+3 种基金the Inner Mongolia Autonomous Region Science and Technology Plan Project(No.2020GG0313)the Inner Mongolia Autonomous Region Natural Science Foundation Doctoral Fund Project,(No.2021BS05016)the Construction project of integrated research and development platform for key technologies in the development and processing of new nonferrous metal materials(No.RZ2300001971)the Basic Research Business Fee Project for Autonomous Region Directly Affiliated Universities(Nos.JY20220199 and JY20220028).
文摘An alternating magnetic field(AMF)was introduced into the narrow gap laser-arc hybrid welding process for 2205 duplex stainless steel thick plates.The corrosion performance of the welded joints was evaluated through electrochemical studies.The results revealed that joints welded with the application of AMF had a lower corrosion current density compared to those welded without an external AMF.Additionally,these joints showed higher pitting potential and polarization resistance.Microscopic electrochemical analysis indicated that joints subjected to AMF exhibited minimal cathodic current in simulated seawater,with only slight fluctuations in the anodic current peak.Overall,the corrosion levels on the joint surfaces were relatively low.After 4 h of immersion in the corrosive medium,the average impedance of joints exposed to AMF increased by 60.7%compared to those not influenced by a magnetic field.These findings suggest that applying AMF during the narrow gap laser-arc hybrid welding process can significantly improve the corrosion resistance of duplex stainless steel welded joints,reducing their susceptibility to stress corrosion in seawater-like environments.
基金supported by grants from the National Natural Science Foundation of China(31572381)National Thousand Youth Talents Plan of the International Science and Technology Cooperation Project of China(2013DFA31420)Science and Technology Innovation Capability Promotion Program of the Science and Technology Department of Qinghai Province(2015-ZJ-712)
文摘Divergence of gene expression and alter native splicing is a crucial driving force in the evolution of species;to date, however the molecular mechanism remains unclear. Hybrids of closely related species provide a suitable model to analyze allele-specific expressi on (ASE) and allele-specific alter native splicing (ASS). Analysis of ASE and ASS can uncover the differences in cis-regulatory elements between closely related species, while eliminating interferenee of trans-regulatory elements. Here, we provide a detailed characterization of ASE and ASS from 19 and 10 transcriptome datasets across five tissues from reciprocal-cross hybrids of horsex don key (mule/hi nny) and cattlexyak (dzo), respectively. Results showed that 4.8%-8.7% and 10.8%-16.7% of genes exhibited ASE and ASS, respectively. Notably, IncRNAs and pseudogenes were more likely to show ASE than protein-coding genes. In addition, genes showing ASE and ASS in mule/hinny were found to be involved in the regulation of muscle strength, whereas those of dzo were involved in high-altitude adaptati on. In con clusi on, our study dem on strated that explorati on of genes showing ASE and ASS in hybrids of closely related species is feasible for species evolution research.
文摘In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a conductive, stable plasma channel for arcs. Plasma radiation strengthened especially in the center of the arc after hybrid. High temperature plasma erupting from keyhole provides an upward reacting force which can prevent droplet from transfer. The charged particles consisted in high temperature plasma reduce the voltage that maintains arc ignition or burning. The results show that laser can influence the arc shape, prevent droplet transfer, reduce resistivity and stabilize arcs.
基金supported by the National Natural Science Foundation of China(72271213)the Shenzhen Science and Technology Program(JCYJ20220530143800001 and RCYX20221008092927070)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(2024A1515240024)the National Key Research and Development Program of China(2022YFB2403500).
文摘Interconnection planning involving bi-directional converters(BdCs)is crucial for enhancing the reliability and robustness of hybrid alternating current(AC)/direct current(DC)microgrid clusters with high penetrations of renewable energy resources(RESs).However,challenges such as the non-convex nature of BdC efficiency and renewable energy uncertainty complicate the planning process.To address these issues,this paper proposes a tri-level BdC-based planning framework that incorporates dynamic BdC efficiency and a data-correlated uncertainty set(DcUS)derived from historical data patterns.The proposed framework employs a least-squares approximation to linearize BdC efficiency and constructs the DcUS to balance computational efficiency and solution robustness.Additionally,a fully parallel column and constraint generation algorithm is developed to solve the model efficiently.Numerical simulations on a practical hybrid AC/DC microgrid system demonstrate that the proposed method reduces interconnection costs by up to 21.8%compared to conventional uncertainty sets while ensuring robust operation under all considered scenarios.These results highlight the computational efficiency,robustness,and practicality of the proposed approach,making it a promising solution for modern power systems.
基金supported by NSFC (No. 61571055)fund of SKL of MMW (No. K201815)Important National Science & Technology Specific Projects (2017ZX03001028)
文摘Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.
文摘The central aim of this paper is to provide an upto-date snapshot of hybrid and hydrogen technology-related developments and activities in the North American heavy haul railway setting,placed in the context of the transportation industry more broadly.An overview of relevant alternative propulsion technologies is provided,including a discussion of applicability to the transportation sector in general and heavy haul freight rail specifically.This is followed by a discussion of current developments and research in alternative and blended fuels,discussed again in both general and specific settings.Key factors and technical considerations for heavy haul applications are reviewed,followed by a discussion of non-technical and human factors that motivate a move toward clean energy in North American Heavy Haul systems.Finally,current project activities are described to provide a clear understanding of both the status and trajectory of hybrid and hydrogen technologies in the established context.
文摘Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions.
基金supported partly by the National Basic Research Program of China(″973″Program)(No.2014CB046200)
文摘A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems. The near body region is discretized by using the body-fitted structured grids, while the remaining computational domain is tessellated with the generated Cartesian grids. As the body moves, the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication. By using the alternating digital tree （ADT） algorithm, the computational time of hole-cutting and identification of donor cells can be reduced significantly. A compressible solver for unsteady flow problems is developed. A cell-centered, second-order accurate finite volume method is employed in spatial discreti- zation and an implicit dual-time stepping low-upper symmetric Gauss-Seidei （LU-SGS） approach is employed in temporal discretization. Geometry-based adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weigh- ting interpolation formula. Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method. Then, a 2-D store separation problem is simulated. The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.
文摘Recently global warming and the depletion of fuel resources have accelerated researchers’ efforts to produce more efficient and clean alternatives. This research presents a comprehensive review of the different adjustments/con figurations of electric vehicles (EVs) and hybrid electric vehicles (HEVs), traction motors for power systems, and wireless speed control of traction drive. Electronic installation of technology can reduce pollution efficiently and effectively. The efficient operation has always been one of the most common investigators’ objectives in the automotive industry and academic areas. There are several renewable energy resources for hybrid vehicles that will replace depleted gasoline worldwide. The purpose of this paper is the development of more efficient pure EVs, HEVs, and fuel cell electric vehicles (FCEV) present both a challenge and a definite solution to current mobility issues. Fuel consumption in cars is a concern due to the harmful effects on the environment. Among other battery sources, fuel cells (FC), super capacitors (SC), and photovoltaic cells are studied for vehicle application. A combination of these renewable energy sources can be used for hybrid electric vehicles (HEV) in the next generation of transportation. With the significant progress of automobile technology, the hybrid electric vehicle has already become the main achievement of transportation electrification due to its excellent fuel-saving performance.
文摘针对多输入多输出(multiple-input multiple-output,MIMO)雷达通信一体化(dual-function radarcommunication,DFRC)系统性能对信道状态信息(channel state information,CSI)精度敏感的问题,构建了非完美CSI条件下的模数混合波束形成设计模型,提出了一种鲁棒的混合波束形成器优化方法。利用CSI误差的先验统计信息,在满足通信中断概率约束的同时最小化雷达方向图加权均方误差,以得到期望的发射数字和模拟波束形成矩阵。所提出的非凸优化问题首先利用坎泰利(Cantelli)不等式进行近似处理,再利用交替方向乘子法(alternating direction method of multipliers,ADMM)求解。仿真实验对比了多种算法之间的性能差异,验证了所提出的MIMO-DFRC混合波束形成设计方法具有高效性和鲁棒性。
