检索结果-南通市图书馆

Influence of Surface Ice Roughness on the Aerodynamic Performance of Wind Turbines

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2024年第9期20卷 2029-2043页

作者： Xin Guan Mingyang Li Shiwei Wu Yuqi Xie yongpeng Sun School of New Energy Shenyang Engineering CollegeShenyang110136China Shenyang Key Laboratory Clean Energy Fine Comprehensive Utilization and Scheduling Energy Storage Shenyang110136China

The focus of this research was on the equivalent particle roughness height correction required to account for the presence of ice when determining the performances of wind *** particular,two icing processes(frost ice and clear ice)were examined by combining the FENSAP-ICE and FLUENT analysis *** ice type on the blade surfaces was predicted by using a multi-time step ***,the influence of variations in icing shape and ice surface roughness on the aerodynamic performance of blades during frost ice formation or clear ice formation was *** results indicate that differences in blade surface roughness and heat flux lead to disparities in both ice formation rate and shape between frost ice and clear *** ice has a greater impact on aerodynamics compared to frost ice,while frost ice is significantly influenced by the roughness of its icy surface.

关键词： Wind turbine icing blade surface roughness aerodynamic characteristics airfoil

Torsional negative stiffness mechanism by thin strips

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2019年第3期9卷 206-211页

作者： Jinyou Li Kangjia Fu yongpeng Gu Zhihua Zhao School of Aerospace Engineering Tsinghua University

Negative stiffness mechanisms have great application potential in different fields, such as vibration isolation, energy absorption and mesh antenna unfolding. Although numerous compliant mechanisms with negative stiffness features have been implemented in literature, the designing work remains in its infancy, and proposing an original design strategy may open a new avenue for the future inventions. In this study, inspired by a toy, we developed a novel type of compliant mechanism composed of thin strips, possessing negative stiffness property under torsion. The negative stiffness feature is achieved by large deformation of the strips rather than mechanical buckling. As a consequence, the obtained negative stiffness segment covers a significantly long range. Demonstrated with examples, it was shown that the proposed mechanisms could be combined with other compliant mechanisms to realize long-range unusual torque-angle relationships, which can be used in different applications.

关键词： Negative stiffness Compliant mechanism Strip Torsional spring Flexible multibody system

N-doped graphene grown on silk cocoon-derived interconnected carbon fibers for oxygen reduction reaction and photocatalytic hydrogen production

在线全文

学校读者我要写书评

暂无评论

Nano Research 2016年第8期9卷 2498-2509页

作者： yongpeng Lei Qi Shi Cheng Han Bing Wang Nan Wu Hong Wang Yingde Wang College of Basic Education National University of Defense Technology Changsha 410073 China Science and Technology on Advanced Ceramic Fiber and Composites Laboratory National University of Defense Technology Changsha 410073 China College of Materials Science and Engineering Wuhan Textile University Wuhan 430074 China Luoyang Ship Material Research Institute Luoyang 477039 China

Carbon-based metal-free catalysts are a promising substitute for the rare and expensive platinum （Pt） used in the oxygen reduction reaction. We herein report N-doped graphene （NG） that is exquisitely integrated into highly conductive frameworks, simultaneously providing more active sites and higher conductivity. The NG was in situ grown on carbon fibers derived from silk cocoon （SCCf） using a simple one-step thermal treatment. The resulting product （NG-SCCf）, possessing a meso-/macroporous structure with three-dimensional （3D） interconnected networks, exhibits an onset potential that is only 0.1 V less negative than that of Pt/C and shows stability and methanol tolerance superior to those of Pt/C in alkaline media. Moreover, in the absence of Pt as co-catalyst, NG-SCCf shows a photocatalytic H2 production rate of 66.0 ~tmol-h l.g 1, 4.4-fold higher than that of SCCf. This outstanding activity is intimately related to the in situ grown NG, hierarchically porous structure, and 3D interconnected networks, which not only introduce more active sites but also enable smooth electron transfer, mass transport, and effective separation of electron-hole pairs. Considering the abundance of the green raw material in combination with easy and low-cost preparation, this work contributes to the development of advanced sustainable catalysts in energy storage/conversion fields, such as electro- and photocatalysis.

关键词： N-doped graphene silk cocoon interconnected carbonfibers oxygen reduction reaction photocatalytic hydrogenproduction

Multiple Input / Output Delays Compensation for Networked MIMO Systems

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Multiple Input / Output Delays Compensation for Networked MI...

Weighted sum power maximization for STAR-RIS-aided SWIPT systems with nonlinear energy harvesting

第25届中国控制与决策会议

作者： Xiangxin Meng yongpeng Zhang Jian Zhang School of Mechanical Engineering Southwest Jiaotong University Department of Engineering Technology Prairie View A&M University Department of Electrical and Computer Engineering Prairie View A&M University

ISBN: (纸本)9781467355339

With the ever increasing complexity of Networked Control System, system integration is becoming much more challenging. It is because the individual controller designed in delay-free environment may not work properly in networking environment, especially when interconnected coupling between distributed nodes are involved. To address such a challenge, this paper proposes a virtual observer to realize multiple delays spin-off from the closed-loop system. To this end, input/output delays are firstly combined and allocated to the output side, and the resulting system is equivalent to the original one in terms of input-output relationship. Then a virtual observer is utilized based on the derived virtual plant with combined output delays, and delay-free states can be retrieved for feedback. Since the resulting closed-loop characteristic equation is equivalent to that of the delay-free system, the original controller can still achieve a comparable performance in networking environment. Finally, the 2D helicopter is utilized to demonstrate the effectiveness of the proposed methodology through software simulations and hardware experiments.

关键词： MIMO Time delays LQR Observer Helicopter

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第10期67卷 343-358页

作者： Weiping SHI Cunhua PAN Feng SHU yongpeng WU Jiangzhou WANG Yongqiang BAO Jin TIAN School of Network and Communication Nanjing Vocational College of Information Technology National Mobile Communications Research Laboratory Southeast University School of Information and Communication Engineering Hainan University School of Electronic and Optical Engineering Nanjing University of Science and Technology Shanghai Key Laboratory of Navigation and Location Based Services Shanghai Jiao Tong University School of Engineering University of Kent School of Information and Communication Engineering Nanjing Institute of Technology Engineering School of Networks and Telecommunications Jinling Institute of Technology

The conventional reconfigurable intelligent surface(RIS) is limited to reflecting incident signals,thereby imposing constraints on the placement of the transmitter and receiver, which hinders achieving comprehensive signal coverage across an entire area. This paper investigates a simultaneously transmitting and reflecting(STAR)-RIS-aided simultaneous wireless information and power transfer(SWIPT) system with a nonlinear energy harvesting model under three different RIS transmission protocols: energy splitting(ES),time switching(TS), and mode switching(MS). The objective of this paper is to maximize the weighted sum power(WSP) of all energy harvesting receivers(EHRs) while ensuring fairness in the collected power among them. This is achieved by jointly optimizing the transmit beamforming at the base station(BS)and the transmission and reflection coefficients at the STAR-RIS, subject to rate constraints for information decoding receivers(IDRs), transmit power constraint at the BS, and coefficient constraints of each element at the STAR-RIS corresponding to the three protocols. Solving this optimization problem poses challenges because of the complicated objective function and numerous coupled optimization variables of the ES STAR-RIS. To address this complexity, an efficient alternating optimization(AO) approach is proposed as an iterative solution method that achieves suboptimal results. The AO algorithm is then extended to MS STAR-RIS and TS STAR-RIS. Specifically, for MS STRA-RIS, binary constraints in the STAR-RIS coefficient optimization subproblem are handled using the first-order approximation technique along with the penalty function method. For TS STAR-RIS, apart from optimizing BS transmit beamforming and STAR-RIS coefficients subproblems, the transmission and reflection time allocation of STAR-RIS also needs *** findings demonstrate that compared to conventional RIS-aided systems, utilizing three different protocols in a STAR-RIS-aided sy

关键词： STAR-RIS beamforming SWIPT alternating optimization nonlinear energy harvesting

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

全速度区间内车体多重被动式吸振器减振方法

中南大学学报（自然科学版） 2020年第3期51卷 853-862页

作者：文永蓬宗志祥翁琳邹钰上海工程技术大学城市轨道交通学院上海201620

为了降低轨道车辆车体垂向振动,建立包含多重被动式吸振器的轨道车辆垂向振动模型,讨论一重被动式吸振器对轨道车辆车体的减振效果,指出一重被动式吸振器的局限性,进一步提出多重被动式吸振器的优化算法,明确多重动力吸振器的重数和目... 详细信息

为了降低轨道车辆车体垂向振动,建立包含多重被动式吸振器的轨道车辆垂向振动模型,讨论一重被动式吸振器对轨道车辆车体的减振效果,指出一重被动式吸振器的局限性,进一步提出多重被动式吸振器的优化算法,明确多重动力吸振器的重数和目标频率的选取,从而提出适用于城市轨道车辆在全速度区间内车体多重被动式吸振器的减振方法,最后分析多重被动式吸振器能够实现全速度减振的原因,并验证该方法的有效性。研究结果表明:多重被动式吸振器能够实现全速度减振的关键在于吸振器重数和目标频率的选取,其中,吸振器重数要选取三重以上;目标频率的选取要包含最小峰值频率和最大峰值频率,并兼顾典型频率,使其发挥共同协调作用。多重被动式吸振器在全速度区间内都能减振的原因是多个固有频率不同的动力吸振器能够针对不同振动频率点进行减振,从而拓宽了动力吸振器的吸振频带。

关键词：车体多重被动式吸振器减振 Sperling指标目标频率

N-doped defective carbon with trace Co for efficient rechargeable liquid electrolyte-/all-solid-state Zn-air batteries

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2018年第9期63卷 548-555页

作者： Zhiyan Chen Qichen Wang Xiaobin Zhang yongpeng Lei Wei Hu Yao Luo Yaobing Wang College of Materials Science and Engineering Central South University of Forestry and Technology State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University Center for Nano Materials and Technology Japan Advanced Institute of Science and Technology School of Aeronautics and Astronautics & Science and Technology on High Strength Structural Materials Laboratory Central South University College of Basic Education National University of Defense Technology Design and Assembly of Functional Nanostructures Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences

Simple synthesis of multifunctional electrocatalysts with plentiful active sites from earth-abundant materials is especially fascinating. Here, N-doped defective carbon with trace Co （1.5 wt%） was prepared via a scalable one pot solid pyrolysis process. The sample exhibits efficient bifunctional OER/ORR activiW in alkaline, mainly ascribed to the unique micro-mesoporous structure （1-3 nm）, high population of graphitic-N doping （up to 49.0%）, abundant defects and the encapsulated Co nanoparticles with graphitized carbon. The according rechargeahle liquid Zn-air batteries showed excellent performance （maximum power density of 154.0 mWcm-2： energy density of 773Wh kg -1 at 5 mAcm 2 and charging-discharging cycling stability over 100 cycles）. As a proof-of-concept, the flexible, rechargeable all-solid-state Zn-air batteries were constructed, and displayed a maximum power density as high as 45.9 mW cm 2 among the top level of those reported previously.

关键词： Defect Oxygen electrocatalysts Rechargeable all-solid-state batteries

Ab initio Molecular Dynamics Study of Local Atomic Structure Evolution of U–Zr Alloy Melts upon Solidification

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2023年第9期36卷 1549-1558页

作者： Mingfeng Liu Jiantao Wang yongpeng Shi Heyu Zhu Yan Sun Peitao Liu Xing-Qiu Chen Shenyang National Laboratory for Materials Sciences Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China

We study the local atomic structure evolution of UZr and UZr_(2) alloy melts upon solidification through ab initio molecular dynamics *** is achieved by analyzing in detail the temperature dependence of structure factors,pair correlation functions,the bond angle distributions,Honeycutt-Anderson index and Voronoi tessellation analysis as well as local bond orientation order *** observe that as the temperature decreases the pair correlation functions and structure factors become more structured with clear distinctions at the liquid–solid phase transition *** Honeycutt-Anderson indices and Voronoi tessellation analysis indicate that the liquid phase is predominantly comprised of the icosahedra-like local structures,whose fraction increases with decreasing temperature up to the transition temperature and then abruptly drops at the transition temperature,whereas the bcc-like local atomic structures dominate during the solidification ***,the bond orientation order analyses with\({\overline{w}}_{6}\)–\({\overline{q}}_{6}\)correlation map and bond angle distribution imply that the local structures mainly consist of the bcc-type during the solidification below the transition *** the analyses are consistent with each other,showing a first-order liquid to solid phase transition for both UZr and UZr_(2) solid solutions,which only differ in different predicted transition *** work provides a comprehensive insight into the detailed local structure evolution during the solidification of the U–Zr alloy melts at the atomic *** strategies used here can be extended to studying the liquid–solid phase transition in other alloy systems.

关键词： Local atomic structure Molecular dynamics Solidification U-Zr alloy melts

Hierarchical Ag-SiO_2@Fe_3O_4magnetic composites for elemental mercury removal from non-ferrous metal smelting flue gas

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2019年第5期31卷 111-120页

作者： yongpeng Ma Bailong Mu Xiaojing Zhang Hongzhong Zhang Haomiao Xu Zan Qu Li Gao Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration School of Material and Chemical Engineering Zhengzhou University of Light Industry School of Environmental Science and Engineering Shanghai Jiao Tong University College of Resources and Environmental Science Ningxia University

Hierarchical Ag-SiO_2@Fe_3O_4 magnetic composites were selected for elemental mercury(Hg^0) removal from non-ferrous metal smelting flue gas in this study. Results showed that the hierarchical Ag-SiO_2@Fe_3O_4 magnetic composites had favorable Hg^0 removal ability at low temperature. Moreover, the adsorption capacity of hierarchical magnetic composite is much larger than that of pure Fe_3O_4 and SiO_2@Fe_3O_4. The Hg^0 removal efficiency reached the highest value as approximately 92% under the reaction temperature of 150°C, while the removal efficiency sharply reduced in the absence of O_2. The characterization results indicated that Ag nanoparticles grew on the surface of SiO_2@Fe_3O_4 support. The large surface area of SiO_2 supplied efficient reaction room for Hg and Ag atoms. Ag–Hg amalgam is generated on the surface of the composites. In addition, this magnetic material could be easily separated from fly ashes when adopted for treating real flue gas, and the spent materials could be regenerated using a simple thermal-desorption method.

关键词： Elemental mercury Silver nanoparticles Magnetic composites Non-ferrous metal Flue gas