检索结果-内蒙古大学图书馆

arXiv 2025年

作者： Luo, Chensheng Fang, Le Fang, Jian Xu, Haitao Pumir, Alain Yang, Ping-Fan School of Aeronautics Institute of Extreme Mechanics Northwestern Polytechnical University Xi’an710072 China Research Institute of Aero-Engine Beihang University Beijing100191 China Laboratory of Complex System Ecole Centrale de Pékin School of General Engineering Beihang University Beijing100191 China Scientific Computing Department STFC Daresbury Laboratory WarringtonWA4 4AD United Kingdom Center for Combustion Energy School of Aerospace Engineering Tsinghua University Beijing100084 China Laboratoire de Physique Ecole Normale Supérieure de Lyon CNRS Université de Lyon LyonF-69007 France National Key Laboratory of Aircraft Configuration Design Xi’an710072 China

We analyze the energy flux in compressible turbulence by generalizing the exact decomposition recently proposed by Johnson (Phys. Rev. Lett., vol. 124, 2020. 104501) to study incompressible turbulent flows. This allows us to characterize the effect of dilatational motion on the inter-scale energy transfer in three-dimensional compressible turbulence. Our analysis reveals that the contribution of dilatational motion to energy transfer is due to three different physical mechanisms: the interaction between dilatation and strain, between dilatation and vorticity, and the self-interaction of dilatational motion across scales. By analyzing numerical simulations of flows at moderate turbulent Mach numbers (Mat 0.3), we validate our theoretical derivations and provide a quantitative description of the role of dilatational motion in energy transfer. In particular, we determine the scaling dependence of the dilatational contributions on the turbulent Mach number. Moreover, our findings reveal that the eddy-viscosity assumption often used in large-eddy simulations, in the spirit of the approach used for incompressible flows, effectively neglects the interaction between solenoidal-dilatational energy transfer and overestimate dilatational effects. Copyright © 2025, The Authors. All rights reserved.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Aerodynamic load extraction in the real-time hybrid model test for floating wind turbine

引用

Ocean engineering 2025年 333卷

作者： Jiang, Zhihao Gao, Yuning Tian, Xinliang Chen, Gang Wen, Binrong Peng, Zhike Zhang, Wei Yang, Mindong Gao, Yang State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China SJTU Yazhou Bay Institute of Deepsea Technology Sanya57200 China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China School of Mechanical Engineering Ningxia University Yinchuan750021 China CPI Xinjiang Energy & Chemical Group Bozhou Co. Ltd Bozhou833400 China China Energy Engineering Group Guangdong Electric Power Design Institute Co. Ltd. Guangzhou510663 China Goldwind Sci & Tech Co. Ltd. Beijing100176 China

Physical model test is of great importance in testing new concepts in the field of ocean engineering, and floating wind turbine (FWT), a newly emerging renewable energy developing equipment, is of no exception. However, with the development trend of FWTs towards deeper waters and larger sizes, challenges and higher demands of physical model test are raised. Therefore, the real-time hybrid testing (RTHT) method is a new approach to breakthrough. And the RTHT method in wind tunnel can be applied to evaluate the aerodynamic performance, the control strategy of the wind turbine and the coupling effects between the wind turbine and floating support. This technical route highly relies on the real-time data interaction and aerodynamic load extraction. In the work of this paper, the aerodynamic load extraction method based on load and acceleration measurements is adopted. The performance of the method was evaluated under both steady wind and turbulent wind cases. Then the influence of parametric errors in mass and inertia of the model wind turbine on the RTHT system operation was studied through turbulent wind and irregular wave joint cases. The results indicate that the adopted load extraction method can properly identify the aerodynamic load in the real time. The studied RTHT system is more sensitive to gravitational parameter error than to the inertial parameter error. Under the same level of error, the reproduction of pitch motion is more sensitive among the 3 main discussed degrees of freedom. The study in this paper provides references and support for the data interaction and processing during the practice of the RTHT in wind tunnel. © 2025 Elsevier Ltd

关键词： Ocean engineering

来源：评论

学校读者我要写书评

暂无评论

Categorical Spatial Interpolation of Solar Irradiance for Regional Distributed Photovoltaic Power Forecasting

引用

IEEE Transactions on Sustainable Energy 2025年

作者： Ruan, Chenglong Li, Kangping Li, Zhenghui Huang, Chunyi Wang, Fei Shanghai Jiao Tong University College of Smart Energy Shanghai200240 China Shanghai Jiao Tong University Shanghai Non-Carbon Energy Conversion and Utilization Institute Shanghai200240 China Ministry of Education Shanghai Jiao Tong University Key Laboratory of Control of Power Transmission and Conversion Shanghai200240 China North China Electric Power University Department of Electrical Engineering Baoding071003 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing102206 China Hebei Key Laboratory of Distributed Energy Storage and Microgrid North China Electric Power University Baoding071003 China

High-spatial-resolution (HSR) solar irradiance forecast data is important for regional distributed photovoltaic (PV) power forecasting. Distributed PV sites are widely geographically distributed and the cost of obtaining HSR irradiance forecast data with full regional coverage is very high. Improving spatial resolution through interpolation based on limited sparse irradiance forecast reference points is a low-cost and feasible approach. However, existing irradiance spatial interpolation methods would produce large errors under variable weather conditions (e.g., cloudy) with limited reference points, because local abrupt changes in irradiance usually occur under such weather conditions due to cloud movement. This paper proposes a categorical spatial interpolation method to improve the accuracy of distributed PV power forecasting with limited sparse irradiance forecast data. The method first converts satellite-derived shortwave radiation images into binary irradiance maps through adaptive thresholding, then trains a 3D U-net model to predict future irradiance category probabilities for each grid. These probability maps dynamically govern two parallel interpolation processes: one using reference stations in predicted clear-sky regions, another utilizing stations in cloudy zones, with final irradiance values determined by probability-weighted fusion. Case studies on a real dataset verify the effectiveness and superiority of the proposed method. © 2025 IEEE.

关键词： Solar irradiance

来源：评论

学校读者我要写书评

暂无评论

STAR-RIS Enabled ISAC systems With RSMA: Joint Rate Splitting and Beamforming Optimization

引用

IEEE Transactions on Cognitive Communications and Networking 2025年

作者： Liu, Yuan Zhang, Ruichen Jiang, Ruihong Zhu, Yongdong Hu, Huimin Ni, Qiang Fei, Zesong Niyato, Dusit Zhejiang Laboratory Research Center for Space Computing System Hangzhou311100 China Nanyang Technological University College of Computing and Data Science Singapore 639798 Singapore Beijing University of Posts and Telecommunications State Key Laboratory of Networking and Switching Technology Beijing100876 China Cambridge Mechatronics Ltd CambridgeCB1 2PH United Kingdom Xi’an University of Posts and Telecommunications School of Communications and Information Engineering School of Artificial Intelligence Xi’an710121 China Lancaster University School of Computing and Communications LancasterLA1 4WA United Kingdom Beijing Institute of Technology School of Information and Electronics Beijing100081 China

This paper delves into an integrated sensing and communication (ISAC) system bolstered by a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS). Within this system, a base station (BS) is equipped with communication and radar capabilities, enabling it to communicate with ground terminals (GTs) and concurrently probe for echo signals from a target of interest. Moreover, to manage interference and improve communication quality, the rate splitting multiple access (RSMA) scheme is incorporated into the system. The signal-to-interference-plus-noise ratio (SINR) of the received sensing echo signals is a measure of sensing performance. We formulate a joint optimization problem of common rates, transmit beamforming at the BS, and passive beamforming vectors of the STAR-RIS. The objective is to maximize sensing SINR while guaranteeing the communication rate requirements for each GT. We present an iterative algorithm to address the non-convex problem by invoking Dinkelbach’s transform, semidefinite relaxation (SDR), majorization-minimization, and sequential rank-one constraint relaxation (SROCR) theories. simulation results manifest that the performance of the studied ISAC network enhanced by the STAR-RIS and RSMA surpasses other benchmarks considerably. The results evidently indicate the superior performance improvement of the ISAC system with the proposed RSMA-based transmission strategy design and the dynamic optimization of both transmission and reflection beamforming at STAR-RIS. © 2015 IEEE.

关键词： Signal to noise ratio

来源：评论

学校读者我要写书评

暂无评论

Development of database of real-world diesel vehicle emission factors for China

引用

Journal of Environmental Sciences 2015年第5期27卷 209-220页

作者： Xianbao Shen Zhiliang Yao Qiang Zhang David Vance Wagner Hong Huo Yingzhi Zhang Bo Zheng Kebin He State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University School of Food and Chemical Engineering Beijing Technology and Business University Ministry of Education Key Laboratory for Earth System Modeling Center for Earth System Science Tsinghua University International Council on Clean Transportation (ICCT) Institute of Energy Environment and Economy Tsinghua University State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Tsinghua University

A database of real-world diesel vehicle emission factors, based on type and technology, has been developed following tests on more than 300 diesel vehicles in China using a portable emission measurement system. The database provides better understanding of diesel vehicle emissions under actual driving conditions. We found that although new regulations have reduced real-world emission levels of diesel trucks and buses significantly for most pollutants in China, NOx emissions have been inadequately controlled by the current standards, especially for diesel buses, because of bad driving conditions in the real world. We also compared the emission factors in the database with those calculated by emission factor models and used in inventory studies. The emission factors derived from COPERT（Computer Programmer to calculate Emissions from Road Transport） and MOBILE may both underestimate real emission factors, whereas the updated COPERT and PART5（Highway Vehicle Particulate Emission Modeling Software） models may overestimate emission factors in China. Real-world measurement results and emission factors used in recent emission inventory studies are inconsistent,which has led to inaccurate estimates of emissions from diesel trucks and buses over recent years. This suggests that emission factors derived from European or US-based models will not truly represent real-world emissions in China. Therefore, it is useful and necessary to conduct systematic real-world measurements of vehicle emissions in China in order to obtain the optimum inputs for emission inventory models.

关键词： Diesel vehicle Emission factor Portable emission measurement system Database China

来源：评论

学校读者我要写书评

暂无评论

Constructing wall turbulence using hierarchically attached hairpin vortices

arXiv

引用

arXiv 2025年

作者： Shen, Weiyu Ge, Yuchen Han, Zishuo Zhao, Yaomin Yang, Yue State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing100871 China Max Planck Institute for Solar System Research Göttingen37077 Germany HEDPS-CAPT Peking University Beijing100871 China

Wall-bounded turbulence is characterized by coherent, worm-like structures such as hairpin vortices. The organization of these vortices near the wall can be modeled using the attached-eddy hypothesis, which effectively describes velocity statistics in the log-law region and energy-containing motions. However, the complex geometry and diverse scales of vortex structures in wall turbulence present significant challenges for developing and applying physics-based models. Here, we model wall turbulence as an ensemble of complex vortices, offering a systematic approach to constructing turbulence fields enriched with hierarchically organized hairpin vortex packets at a range of Reynolds numbers. The geometry and distribution of these vortex packets are calibrated to match physical observations and flow statistics. Our model successfully reproduces key features of wall turbulence, including mean velocity profiles, higher-order velocity fluctuation moments, near-wall streaks, and energy spectra that align with theoretical and numerical findings of turbulent channel flows at friction Reynolds numbers from 1,000 to 10,000. Furthermore, the constructed channel turbulence transitions rapidly to fully developed turbulence through direct numerical simulation, demonstrating its practicality for generating inlet or initial conditions in numerical simulations. This approach significantly reduces computational costs associated with turbulence development while providing a robust framework for testing and advancing turbulence models based on vortex structures. Copyright © 2025, The Authors. All rights reserved.

关键词： Computational geometry

来源：评论

学校读者我要写书评

暂无评论

Modeling of service correlation for service composition in cloud manufacturing 31

Modeling of service correlation for service composition in c...

引用

31st European Modeling and simulation Symposium, EMSS 2019

作者： Wang, Fei Laili, Yuanjun Zhang, Lin Xing, Chi Guo, Liqin School of Automation Science and Electrical Engineering Beihang University China Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing Simulation Center China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System Engineering Beijing Simulation Center China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center China

ISBN: (纸本)9788885741263

Cloud manufacturing (CMfg), integrating distributed manufacturing resources as services to cloud center, aims at intelligent, green, and economic customized manufacturing. The optimal composition of services to fulfill particular manufacturing requirement is a core issue to realize efficient cloud manufacturing. Many researchers have studied the problem considering the Quality-of-Service (QoS) of independent services. However, the correlation between services is rarely considered. In this paper, the importance of service correlation is emphasized. Two kinds of service correlation, service exclusion and service collaboration, are modeled for service composition. An improved algorithm DET, which combines Differential Evolution Algorithm (DE) with a Tabu table based on service exclusive and collaborative relationships, is designed to filter composable services and find better solutions for complex tasks. Experiments have shown the effects of service correlation on the quality of composed services and demonstrated the effectiveness of the proposed method DET compared with traditional DE. © 2019 Dime Universita di Genova, DIMEG University of Calabria.

关键词： Quality of service

来源：评论

学校读者我要写书评

暂无评论

BLOOD FLOW AND MACROMOLECULAR TRANSPORT IN CURVED BLOOD VESSELS

引用

Applied Mathematics and Mechanics(English Edition) 2006年第9期27卷 1223-1231页

作者：魏兰温功碧谭文长 Department of Mechanics and Engineering Science State Key Laboratory for Turbulence and Complex System Peking University Beijing 100871 P. R. China Institute of Applied Physics and Computational Mathematics Beijing 100088 P. R. China Department of Mechanics and Engineering Science State Key Laboratory for Turbulence and Complex System Peking University Beijing 100871 P. R. China

A numerical analysis of the steady/pulsatile flow and macromolecular （such as LDL and Albumin） transport in curved blood vessels was carried out. The computational results predict that the vortex of the secondary flow is time-dependent in the aortic arch. The concentration of macromolecule concentrates at the region of sharp curve, and the wall concentration at the outer part is higher than that at the inner part. Atherosclerosis and thrombosis are prone to develop in such regions with sharp flow.

关键词： curved blood vessels blood flow macromolecular transport atherosclerosis

来源：评论

学校读者我要写书评

暂无评论

Contrasting temporal dynamics of land surface temperature responses to different types of forest loss

引用

Innovation 2025年第6期6卷

作者： Li, Jing Li, Zhao-Liang Liu, Xiangyang Li, Yitao Liu, Meng You, Nanshan Wu, Hua He, Lei Si, Menglin Tang, Ronglin Zhou, Chenghu Zhao, Wei Duan, Si-Bo Leng, Pei Liu, Wenqi Zhao, Enyu Tang, Bo-Hui Jin, Zhenong State Key Laboratory of Efficient Utilization of Arable Land in China Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing100081 China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China Key Lab for Resources Use and Environmental Remediation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China School of Resources and Environment University of Electronic Science and Technology of China Chengdu610054 China Guangzhou Institute of Geography Guangdong Academy of Sciences Guangzhou510070 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu610041 China Department of Geography Oklahoma State University StillwaterOK74078 United States College of Information Science and Technology Dalian Maritime University Dalian116026 China Faculty of Land Resource Engineering Kunming University of Science and Technology Kunming650093 China Department of Bioproducts and Biosystems Engineering University of Minnesota St. PaulMN55108 United States Institute of Ecology College of Urban and Environmental Science Peking University Beijing100871 China Peking University Beijing100871 China

Forest loss impacts local climate through biophysical processes. However, our understanding of this impact remains limited due to the neglect of its temporal dynamics. Using a space-and-time scheme that incorporates a change-detection method, we assess the dynamics of land surface temperature (LST) responses to various forest-loss types. Globally, LST increased by 0.12 K one year after forest loss, followed by a decreasing trend of −0.14 K per decade. Deforestation driven by commodity production and urbanization results in persistent warming, while forest disturbances such as shifting agriculture, forestry, and fire trigger diverse response dynamics with significant spatial variation due to differences in subsequent vegetation recovery. These disturbances cause attenuated warming in low and mid-latitudes, while, in the boreal zone, contrasting dynamics are observed: shifting agriculture causes attenuated cooling, whereas forestry and fire result in enhanced cooling. In addition to amplifying the amplitude of the LST seasonal cycle, forest loss also shifts the seasonal phase, which has not been previously reported. These findings demonstrate that climate feedback from forest loss is climate specific, loss-type dependent, and time varying, providing new insights for the development of local climate policies. © 2025 The Author(s)

关键词： Forest ecology

来源：评论

学校读者我要写书评

暂无评论

UNSTEADY FLOWS OF A GENERALIZED SECOND GRADE FLUID WITH THE FRACTIONAL DERIVATIVE MODEL BETWEEN TWO PARALLEL PLATES

引用

Acta Mechanica Sinica 2004年第5期20卷 471-476页

作者：谭文长徐明喻 1 Department of Mechanics and Engineering Science & State Key Laboratory for Turbulence and Complex System Research Peking UniversityBeijing 100871China Institute of Mathematics and Systematical Science Shandong UniversityJinan 250100China

The fractional calculus approach in the constitutive relationship model of a generalized second grade fluid is *** analytical solutions are obtained for a class of unsteady flows for the generalized second grade fluid with the fractional derivative model between two parallel plates by using the Laplace transform and Fourier transform for fractional *** unsteady flows are generated by the impulsive motion or periodic oscillation of one of the *** addition,the solutions of the shear stresses at the plates are also determined.

关键词： fractional derivative unsteady flows generalized second grade fluid parallel plates

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：