Accurate and seamless auxiliary services in the power market can guarantee smooth and continuous power system operation. China’s new round of power system reform has entered a critical period, and reform implementati...Accurate and seamless auxiliary services in the power market can guarantee smooth and continuous power system operation. China’s new round of power system reform has entered a critical period, and reform implementation requires comprehensive improvements in the maturity of the supporting auxiliary service market. This study reviews the development status and evolution path of the European unified power market and the US regional power market, provides experience for the development of China’s regional power market, then identifies the key influencing factors of auxiliary service trading mechanism design in regional power markets. To analyze the rationality of the auxiliary service trading evaluation index, this paper established an evaluation model for assessing regional power markets. Using combined weight optimization, the gray correlation TOPSIS method was applied to comprehensively evaluate auxiliary service trading in the regional power market. Finally, the application of the proposed evaluation method was briefly analyzed to examine four regional power markets in China and evaluate the effectiveness of current market construction in different regions and provide suggestions for future market construction.展开更多
In recent years,countries worldwide have actively advocated electric vehicles for environmental protection.How-ever,restrictions on the driving range and charging have hampered the promotion of electric vehicles.This ...In recent years,countries worldwide have actively advocated electric vehicles for environmental protection.How-ever,restrictions on the driving range and charging have hampered the promotion of electric vehicles.This study proposes a portable,auxiliary photovoltaic power system based on a foldable scissors mechanism for electric vehicles.The system includes a photovoltaic power generation module and an electricity transfer module.The photovoltaic power generation module built based on a foldable scissors mechanism is five times smaller than in its unfolded state,improving its portability in its folded state.The electricity transfer module transfers electricity into the cabin via wireless power transfer units and stores electricity in supercapacitors.Solar simulation exper-iments were conducted to evaluate the system’s performance:maximum output power of 1.736 W is measured when the load is 5Ω,while maximum wireless power transfer efficiency is up to 57.7% with 10Ω load.An elec-tric vehicle in Chengdu city was simulated for a case study.The results show that the annual output of a single photovoltaic power system can drive the MINIEV for 423.625 km,indicating that the proposed system would be able to supply power for electric vehicles as an auxiliary power supply system.展开更多
It is illustrated that there exists an inflection circle on the linkage rigid body by the principle of relative motion. Confirmed methods of the inflection circle, curvature radius and curvature center of the point tr...It is illustrated that there exists an inflection circle on the linkage rigid body by the principle of relative motion. Confirmed methods of the inflection circle, curvature radius and curvature center of the point track on the linkage rigid body are given in the case of the different contact type of move instantaneous center line and static instantaneous center line. The regularity of distribution of curvature radius and curvature center of the point track is researched. The identification methods called determination parameters and auxiliary vertical line of the diameter and direction of the inflection circle in the four bar mechanism are pointed out. A design method of the crane hoisting mechanism is discussed in the end of this paper.展开更多
Dense and submicron-grained NiAl-Al2O3 composite was fabricated by pulse current auxiliary sintering(PCAS).Its microstructure was analyzed by XRD,SEM and TEM,and its mechanical behavior was evaluated through compres...Dense and submicron-grained NiAl-Al2O3 composite was fabricated by pulse current auxiliary sintering(PCAS).Its microstructure was analyzed by XRD,SEM and TEM,and its mechanical behavior was evaluated through compression test and fracture toughness test.The average grain sizes of NiAl and Al2O3 are about 200 nm and 100 nm respectively.The Al2O3 particles dispersed in NiAl matrix,forming intergranular structure and intragranular structure.During sintering,Al2O3 particles were remarkably spherized due to the unique sintering mechanism of PCAS,which is beneficial to the improvement of toughness.The NiAl-Al2O3 composite exhibits high compressive yield strength,whether at room temperature or elevated temperature.Its room-temperature(23 ℃) and elevated-temperature(1 200 ℃) compressive yield strength are up to 2 050 MPa and 140 MPa,respectively.Meanwhile,its fracture toughness is significantly enhanced,which is up to 8.2 MPa?m1/2.It is suggested that the main strengthening-toughening mechanisms are grain refinement strengthening and Al2O3 dispersion strengthening.The fracture of larger NiAl grain is the transgranular cleavage and this is induced by crack tip deflection and grain boundary weakening which are caused by intergranular and intragranular Al2O3 particles,respectively.展开更多
Because of the rapid growth of new energy and the accompanying considerable uncertainty in the power market,the demand for flexibility in a power sys-tem has risen sharply.In the meantime,the market structure of auxil...Because of the rapid growth of new energy and the accompanying considerable uncertainty in the power market,the demand for flexibility in a power sys-tem has risen sharply.In the meantime,the market structure of auxiliary services has changed,resulting in market participants(MPs)benefiting less than expected from providing flexible services.To encourage MPs to provide flexibility,this study proposes a dynamic design framework for an auxiliary service compensation mech-anism.To evaluate the proposed framework,a case study is conducted,examining a peak-shaving service in Liao-ning province in northeast China.First,the operational status and limitations of the typical product,the peak-shaving service,in China’s flexibility auxiliary ser-vices market are analyzed.Then,taking into consideration the time value of the flexible products provided by the MPs,a dynamic mechanism for hierarchical compensation of flexibility auxiliary service costs is proposed,and a mathematical model aimed at optimizing the MPs’comprehensive income is constructed.The results show that,compared with the existing traditional mechanism,the proposed method can effectively guarantee fair remu-neration for the flexibility provider,while easing the tense supply-demand relationship in the flexibility market.展开更多
Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstrea...Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.展开更多
为提高综合能源系统(integrated energy system, IES)低碳规划及优化运行的技术水平,推进能源结构低碳转型及新型电力系统建设,梳理和总结研究学者在IES的模型构建、系统规划、运行调度等方面的研究成果,该文开展了相关领域的综述研究...为提高综合能源系统(integrated energy system, IES)低碳规划及优化运行的技术水平,推进能源结构低碳转型及新型电力系统建设,梳理和总结研究学者在IES的模型构建、系统规划、运行调度等方面的研究成果,该文开展了相关领域的综述研究。首先,阐述了综合能源系统的典型架构、典型设备及其能流特性。其次,针对IES低碳规划和运行策略及其相关支撑技术,分别论述了多态不确定性模型及功率预测、柔性负荷调控策略、IES参与电力辅助服务及其低碳运营机制、优化模型及其求解算法等方面的技术路线及研究成果;研究表明,规划与运行策略是支撑IES低碳、高效、经济运行水平的关键技术,计及不确定性的高维、非线性、多目标、非凸问题的精确建模和快速求解等难点问题亟待深入研究。最后,展望了人工智能、大数据、电力物联网等新技术在IES低碳规划和运行方面的应用前景,归纳了该领域亟待应对的技术挑战和关键问题。展开更多
Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as therma...Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as thermal history,residual stress accumulation,and columnar grain epitaxial growth,consistently hinders their broad application in standardized industrial production.To overcome these challenges,performance-control-oriented hybrid AM(HAM)technologies have been introduced.These technologies,by leveraging external auxiliary processes,aim to regulate microstructural evolution and mechanical properties during metal AM.This paper provides a systematic and detailed review of performance-control-oriented HAM technology,which is categorized into two main groups:energy field-assisted AM(EFed AM,e.g.ultrasonic,electromagnetic,and heat)technologies and interlayer plastic deformation-assisted AM(IPDed AM,e.g.laser shock peening,rolling,ultrasonic peening,and friction stir process)technologies.This review covers the influence of external energy fields on the melting,flow,and solidification behavior of materials,and the regulatory effects of interlayer plastic deformation on grain refinement,nucleation,and recrystallization.Furthermore,the role of performance-control-oriented HAM technologies in managing residual stress conversion,metallurgical defect closure,mechanical property improvement,and anisotropy regulation is thoroughly reviewed and discussed.The review concludes with an analysis of future development trends in EFed AM and IPDed AM technologies.展开更多
基金supported by the Beijing Power Exchange Center (Study on the Medium and Long Term Time Division Transaction Mode and Balance Mechanism of Electric Power)supported by the National Natural Science Foundation of China(No. 72171082)。
文摘Accurate and seamless auxiliary services in the power market can guarantee smooth and continuous power system operation. China’s new round of power system reform has entered a critical period, and reform implementation requires comprehensive improvements in the maturity of the supporting auxiliary service market. This study reviews the development status and evolution path of the European unified power market and the US regional power market, provides experience for the development of China’s regional power market, then identifies the key influencing factors of auxiliary service trading mechanism design in regional power markets. To analyze the rationality of the auxiliary service trading evaluation index, this paper established an evaluation model for assessing regional power markets. Using combined weight optimization, the gray correlation TOPSIS method was applied to comprehensively evaluate auxiliary service trading in the regional power market. Finally, the application of the proposed evaluation method was briefly analyzed to examine four regional power markets in China and evaluate the effectiveness of current market construction in different regions and provide suggestions for future market construction.
基金supported by the National Natural Science Foundation of China under grants no.51975490the Science and Technology Projects of Sichuan under grant nos.2021JDRC0118,2021JDRC0096,2021YFSY0059,and 2021YFQ0055.
文摘In recent years,countries worldwide have actively advocated electric vehicles for environmental protection.How-ever,restrictions on the driving range and charging have hampered the promotion of electric vehicles.This study proposes a portable,auxiliary photovoltaic power system based on a foldable scissors mechanism for electric vehicles.The system includes a photovoltaic power generation module and an electricity transfer module.The photovoltaic power generation module built based on a foldable scissors mechanism is five times smaller than in its unfolded state,improving its portability in its folded state.The electricity transfer module transfers electricity into the cabin via wireless power transfer units and stores electricity in supercapacitors.Solar simulation exper-iments were conducted to evaluate the system’s performance:maximum output power of 1.736 W is measured when the load is 5Ω,while maximum wireless power transfer efficiency is up to 57.7% with 10Ω load.An elec-tric vehicle in Chengdu city was simulated for a case study.The results show that the annual output of a single photovoltaic power system can drive the MINIEV for 423.625 km,indicating that the proposed system would be able to supply power for electric vehicles as an auxiliary power supply system.
文摘It is illustrated that there exists an inflection circle on the linkage rigid body by the principle of relative motion. Confirmed methods of the inflection circle, curvature radius and curvature center of the point track on the linkage rigid body are given in the case of the different contact type of move instantaneous center line and static instantaneous center line. The regularity of distribution of curvature radius and curvature center of the point track is researched. The identification methods called determination parameters and auxiliary vertical line of the diameter and direction of the inflection circle in the four bar mechanism are pointed out. A design method of the crane hoisting mechanism is discussed in the end of this paper.
文摘Dense and submicron-grained NiAl-Al2O3 composite was fabricated by pulse current auxiliary sintering(PCAS).Its microstructure was analyzed by XRD,SEM and TEM,and its mechanical behavior was evaluated through compression test and fracture toughness test.The average grain sizes of NiAl and Al2O3 are about 200 nm and 100 nm respectively.The Al2O3 particles dispersed in NiAl matrix,forming intergranular structure and intragranular structure.During sintering,Al2O3 particles were remarkably spherized due to the unique sintering mechanism of PCAS,which is beneficial to the improvement of toughness.The NiAl-Al2O3 composite exhibits high compressive yield strength,whether at room temperature or elevated temperature.Its room-temperature(23 ℃) and elevated-temperature(1 200 ℃) compressive yield strength are up to 2 050 MPa and 140 MPa,respectively.Meanwhile,its fracture toughness is significantly enhanced,which is up to 8.2 MPa?m1/2.It is suggested that the main strengthening-toughening mechanisms are grain refinement strengthening and Al2O3 dispersion strengthening.The fracture of larger NiAl grain is the transgranular cleavage and this is induced by crack tip deflection and grain boundary weakening which are caused by intergranular and intragranular Al2O3 particles,respectively.
基金supported by the National Key Research and Development Program“Renewable Energy and Thermal Power Coupling Integration and Flexible Operation Control Technology”(No.2019YFB1505400).
文摘Because of the rapid growth of new energy and the accompanying considerable uncertainty in the power market,the demand for flexibility in a power sys-tem has risen sharply.In the meantime,the market structure of auxiliary services has changed,resulting in market participants(MPs)benefiting less than expected from providing flexible services.To encourage MPs to provide flexibility,this study proposes a dynamic design framework for an auxiliary service compensation mech-anism.To evaluate the proposed framework,a case study is conducted,examining a peak-shaving service in Liao-ning province in northeast China.First,the operational status and limitations of the typical product,the peak-shaving service,in China’s flexibility auxiliary ser-vices market are analyzed.Then,taking into consideration the time value of the flexible products provided by the MPs,a dynamic mechanism for hierarchical compensation of flexibility auxiliary service costs is proposed,and a mathematical model aimed at optimizing the MPs’comprehensive income is constructed.The results show that,compared with the existing traditional mechanism,the proposed method can effectively guarantee fair remu-neration for the flexibility provider,while easing the tense supply-demand relationship in the flexibility market.
基金supported by the 2022 MTC Young Individual Research Grants(Grant No.M22K3c0097)the Singapore Research,Innovation and Enterprise(RIE)2025 PlanSingapore Aerospace Programme Cycle 16(Grant No.M2215a0073)。
文摘Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.
文摘为提高综合能源系统(integrated energy system, IES)低碳规划及优化运行的技术水平,推进能源结构低碳转型及新型电力系统建设,梳理和总结研究学者在IES的模型构建、系统规划、运行调度等方面的研究成果,该文开展了相关领域的综述研究。首先,阐述了综合能源系统的典型架构、典型设备及其能流特性。其次,针对IES低碳规划和运行策略及其相关支撑技术,分别论述了多态不确定性模型及功率预测、柔性负荷调控策略、IES参与电力辅助服务及其低碳运营机制、优化模型及其求解算法等方面的技术路线及研究成果;研究表明,规划与运行策略是支撑IES低碳、高效、经济运行水平的关键技术,计及不确定性的高维、非线性、多目标、非凸问题的精确建模和快速求解等难点问题亟待深入研究。最后,展望了人工智能、大数据、电力物联网等新技术在IES低碳规划和运行方面的应用前景,归纳了该领域亟待应对的技术挑战和关键问题。
基金The financial support was provided by National Natural Science Foundation of China(Grant Numbers:52335008,52175409 and 52305469)Jiangsu Provincial Science and Technology Projects in China(Grant Numbers:BE2023026and BE2022069)+1 种基金Natural Science Foundation of Jiangsu Province(No.BK20220530)the Graduate Research Innovation Program of Jiangsu Province in China(Grant Number:KYCX23_3723)。
文摘Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as thermal history,residual stress accumulation,and columnar grain epitaxial growth,consistently hinders their broad application in standardized industrial production.To overcome these challenges,performance-control-oriented hybrid AM(HAM)technologies have been introduced.These technologies,by leveraging external auxiliary processes,aim to regulate microstructural evolution and mechanical properties during metal AM.This paper provides a systematic and detailed review of performance-control-oriented HAM technology,which is categorized into two main groups:energy field-assisted AM(EFed AM,e.g.ultrasonic,electromagnetic,and heat)technologies and interlayer plastic deformation-assisted AM(IPDed AM,e.g.laser shock peening,rolling,ultrasonic peening,and friction stir process)technologies.This review covers the influence of external energy fields on the melting,flow,and solidification behavior of materials,and the regulatory effects of interlayer plastic deformation on grain refinement,nucleation,and recrystallization.Furthermore,the role of performance-control-oriented HAM technologies in managing residual stress conversion,metallurgical defect closure,mechanical property improvement,and anisotropy regulation is thoroughly reviewed and discussed.The review concludes with an analysis of future development trends in EFed AM and IPDed AM technologies.