检索结果-内蒙古大学图书馆

Efects of Defect,Mean Stress and Lower Loading on High Cycle and Very High Cycle Fatigue Behavior of Ti‑6Al‑4V Alloy

引用

Acta Metallurgica Sinica(English Letters) 2025年第3期38卷 435-448页

作者： Yiyun Guo Lei Wu Yibo Shang Chengqi Sun State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China Guobiao(Beijing)Testing&Certifcation Co. Ltd.Beijing 101400China Fundamentals Department Air Force Engineering UniversityXi’an 710051China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering UniversityXi’an 710038China

In this study,the efects of defect,mean stress and lower loading are investigated for high cycle(HCF)and very high cycle fatigue(VHCF)behavior of Ti-6Al-4V *** indicates that the S-N curve of Ti-6Al-4V alloy exhibits a linear decreasing trend or a plateau characteristic in HCF and VHCF regimes,which depends on the defect size and stress *** strength decreases with increasing the defect size,and it is irrespective of stress *** fatigue crack initiates from specimen surface at R=−1 in both HCF and VHCF *** the fatigue crack initiates from the subsurface or the interior of the specimen at R=0.1 in VHCF regime.A sequence of lower stress amplitude below the fatigue strength at 10^(9) cyc has no or negligible infuence on the fatigue life of 10^(5)-10^(9) *** lower stress amplitude in variable amplitude loadings does not afect the failure *** residual compressive stress relaxation is not observed after a large number of lower loadings under ultrasonic frequency fatigue *** formula and Goodman formula give dangerous predictions of VHCF strength for both smooth specimens and specimens with defects.

关键词： Ti-6Al-4V titanium alloy Very high cycle fatigue Defect Stress ratio Lower stress amplitude

来源：评论

学校读者我要写书评

暂无评论

Disparities in carbon emissions across households: insights from daily diet

引用

Frontiers of Environmental Science and engineering 2025年第7期19卷 87-87页

作者： Yue, Jia Weng, Zhixiong Chen, Siyao Tong, Dan Xie, Yang Xu, Meng Ma, Hao School of Business Xiangtan Institute of Technology Xiangtan411100 China Graduate School University of Perpetual Help System DALTA Las Piñas1740 Philippines Institute of Circular Economy Beijing University of Technology Beijing100124 China State Key Laboratory of Materials Low-Carbon Recycling Beijing University of Technology Beijing100124 China Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modeling Institute for Global Change Studies Tsinghua University Beijing100084 China School of Economics and Management Beihang University Beijing100191 China School of Environmental Sciences and Engineering Peking University Beijing100871 China BGRIMM Technology Group Beijing100160 China

This study examines household food carbon emissions in rural China, focusing on the inequality of these emissions and the influence of household characteristics on their variation. Our findings indicate that the average food consumption per rural household is 1031.66 kg. Among all food types, pork contributes the highest share of carbon emissions at 39.75%, followed by beef and mutton at 15.14%, while milk accounts for the lowest share at just 1.38%. Additionally, as household income increases, both food consumption and associated carbon emissions rise accordingly. The food-related carbon emissions tend to be higher in households that are more educated, younger, and larger in size. There are notable regional and income disparities in rural food-related carbon emissions. The regional inequalities appear primarily driven by interactions between different regions, while income inequality is influenced by both intra-group disparities and overlaps among income groups. The results from our threshold regression suggest that carbon emissions are particularly elevated in households where the head has a college-level education or higher, is aged between 32.80 and 33.25 years, and has a household size of three to five members. It is essential to develop and implement flexible policies aimed at reducing the consumption of high-carbon foods. By taking these steps, we can work toward a more sustainable future and promote greater equity in food-related carbon emissions. © Higher Education Press 2025.

关键词： Beef

来源：评论

学校读者我要写书评

暂无评论

Influences of strain rate on mechanical behaviors of unsaturated and quasi-saturated loess under varying drainage conditions

引用

Journal of Rock Mechanics and Geotechnical engineering 2025年第2期17卷 1163-1181页

作者： Tongwei Zhang Sheng Li Hengxing Lan Huyuan Zhang Fanyu Zhang Key Laboratory of Mechanics on Disaster and Environment in Western China College of Civil Engineering and MechanicsLanzhou UniversityLanzhou730000China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China School of Geological Engineering and Geomatics Chang'an UniversityXi'an710064China

Although time-dependent deformation of geomaterials underpins slope-failure prediction models,the influence of strain rate on shearing strength and deformation behavior of loess remains *** consolidated undrained(CU)and drained(CD)triaxial testing elucidated the impact of strain rate(0.005–0.3 mm/min)on strength envelopes,deformation moduli,pore pressures,and dilatancy characteristics of unsaturated and quasi-saturated *** drained conditions with a controlled matric suction of 50 kPa,increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress(qf),initial deformation modulus(Ei),and cohesion(c),while friction angles remained *** displayed initial contractive volumetric strains transitioning to dilation across varying confining *** rates diminished contractive volumetric strains and drainage volumes,indicating reduced densification and strength in the shear *** undrained conditions,both unsaturated and quasi-saturated(pore pressure coefficient B=0.75)loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/*** unsaturated loess,reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress *** strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective *** porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain *** to previous studies,the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent *** underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides.

关键词： Unsaturated loess Strain rate Shearing strength Deformation modulus Drainage conditions

来源：评论

学校读者我要写书评

暂无评论

A Two-Stage Payload Dynamic Parameter Identification Method for Interactive Industrial Robots With Large Components

引用

IEEE Transactions on Automation Science and engineering 2025年 22卷 13871-13883页

作者： Liu, Mingxuan Li, Pengcheng Duan, Jinjun Liu, Lunqian Shen, Ye Tian, Wei Ji, Yuqi Nanjing University of Aeronautics and Astronautics College of Mechanical and Electrical Engineering Nanjing210016 China State Key Laboratory of Intelligent Manufacturing System Technology for Complex Products Beijing100854 China Shanghai Aircraft Manufacturing Company Shanghai200120 China Shanghai Aerospace Electronic Technology Research Institute Shanghai201109 China

Taking human-robot collaborative assembly as an example, the methods based on contact forces can improve the assembly efficiency of industrial robots with large components in industrial manufacturing. However, due to the large size, high payload, assembly accuracy and dynamic changes in grip position, accurately estimating the contact forces between the payload and the operator becomes challenging when handling these large components. In this paper, a two-stage method is proposed for payload dynamic parameter identification. The parameter identification equation in the sensor coordinate system is initially established. Furthermore, the identification model of recursive restricted total least squares (RRTLS) based on total least squares (TLS) is constructed to achieve low-consumption online identification. According to the assembly requirements and payload characteristics, the posture coordinate system is designed for safety, including the feasible workspace for the robot. Subsequently, the static identification postures and dynamic excitation trajectory are planned to obtain static values and dynamic inertial parameters. In the end, a high-payload human-robot collaborative assembly system is built to validate the proposed method. Experimental results show that compared with the existing methods, the proposed approach can effectively identify and compensate the payload, leading to more accurate external force sensing. © 2004-2012 IEEE.

关键词： Industrial robots

来源：评论

学校读者我要写书评

暂无评论

Investigation of the Effect of Bonding Wires Degradation on Switching Stress Waves Released During Power Cycling in Discrete IGBT

引用

IEEE Journal of Emerging and Selected Topics in Power Electronics 2025年第2期13卷 2057-2069页

作者： Geng, Xuefeng He, Yunze Tang, Longhai Chang, Shan Zhang, Jie Yang, Wenxue Yuan, Man Wang, Guangxin Li, Qiying Ping, Yang Huang, Songling Hunan University College of Electrical and Information Engineering Changsha410082 China Tsinghua University State Key Laboratory of Power System Operation and Control Beijing100084 China Hunan University Shenzhen Research Institute Shenzhen518000 China Tsinghua University Department of Electrical Engineering Beijing100084 China

Effective condition monitoring (CM) technology ensures the safe operation of insulated gate bipolar transistors (IGBTs). Most CM methods for IGBTs focus on extracting electrical, thermal, and magnetic parameters. Recent studies indicate that at the switching moment, IGBTs can emit the switching stress wave (SSW) that is detectable by the acoustic emission (AE) sensors. However, using these SSWs to monitor the health status of IGBTs, even for discrete devices with relatively simple package structures, remains challenging. This article investigates how SSWs from discrete IGBTs during power cycling change as bonding wires degrade and whether these waves are promising for monitoring the condition of internal bonding wires. In this work, a power cycle test platform and an SSW test platform for discrete IGBTs are built, and SSWs from discrete IGBTs during power cycling are analyzed. Results show that SSWs vary with the degradation of the device’s bonding wires, with changes in the time domain indicator of signal energy, reflecting SSW strength, and the frequency domain indicator of the center of gravity (COG) frequency, reflecting frequency shifts. These findings suggest the possibility for developing AE-based detection technology (AEDT) in CM of the IGBT. © 2013 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

来源：评论

学校读者我要写书评

暂无评论

Experimental demonstration of D-band signals wireless transmission over 30 km

引用

Science China(Technological Sciences) 2025年第2期68卷 318-320页

作者： Yi WEI Xiongwei YANG Jianjun YU Xianming ZHAO Mingxu WANG Jingwen TAN Weiping LI Feng ZHAO Chengzhen BIAN Hansong MA Qinyi ZHANG Qiutong ZHANG Bing Zhang Wen ZHOU Kaihui WANG Sicong XU Jianguo YU State Key Laboratory of ASIC and System Key Laboratory for Information Science of Electromagnetic Waves(MoE)and School of Information Science and TechnologyFudan UniversityShanghai 200433China Harbin Institute of Technology Harbin 150001China School of Automation Xi’an University of Posts and TelecommunicationsXi’an 710121China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Due to the rise of innovative technologies like artificial intelligence(AI),the Internet of Things(IoT),and telemedicine,the demand for internet traffic is rapidly *** order to achieve ultra-high-speed wireless communication,many researchers are directing their efforts towards the *** D-band,spanning the frequency band 110-170 GHz,has abundant spectrum resources and license-free characteristics[1,2].

关键词： IoT wireless band

来源：评论

学校读者我要写书评

暂无评论

Atomically thin MoS_(2)with ultra-low friction properties based on strong interface interaction

引用

Friction 2025年第4期13卷 139-148页

作者： Xinjian He Tongtong Yu Zishuai Wu Changhe Du Haoyu Deng Yongkang Zhao Shuang Li Yange Feng Liqiang Zhang Zhinan Zhang Daoai Wang State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of ChineseAcademy of SciencesBeijing 100049China Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai Yantai 265503China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Qingdao Center of Resource Chemistry and New Materials Qingdao 266100China

Atomically thin lubrication materials with anti-friction properties are crucial for reducing energy consumption and extending the servicelifeofmicro/nanoelectromechanical systems(MEMS/NEMS).However,achieving atomically thin films with ultra-low friction properties at the atomic/nanoscale even at the micrometer scale presents significant *** this study,large-size and high-quality monolayer MoS_(2)(ML MoS_(2))was grown on SiO2/Si substrate by chemical vapor deposition(CVD)*** with mechanically exfoliated ML MoS_(2),the CVD-grown ML MoS,(CVD-MoS_(2))exhibits an ultra-lower friction coefficient(0.00904).Based on the stick-slip effect and Prandtl-Tomlinson(P-T)model,the reduction of puckering effect indicates stronger interaction and lower interface potential barrier in tip,CVD-MoS_(2),and SiO,/Si substrate ***,combining with the density functional theory calculations,the stronger interface adhesion and higher overall charge redistribution degree of CVD-MoS_(2)can also be used to explain its ultralow friction *** work will provide theoretical guidance for designing ultra-thin lubricating materials with ultra-low friction properties.

关键词： chemical vapor deposition(CVD) MoS_(2) ultra-thin ultra-low friction interface interaction

来源：评论

学校读者我要写书评

暂无评论

Dynamic Response Characteristics of Multi-Generation system Integrated with Gas and Heat Storage

引用

Journal of Thermal Science 2025年第3期34卷 913-935页

作者： WANG Xiaomeng DUAN Liqiang ZHENG Nan WANG Qiushi Beijing Laboratory of New Energy Storage Technology North China Electric Power University School of Energy Power and Mechanical Engineering North China Electric Power University State Key Laboratory of Alternate Electric Power System with Renewable Energy Sources (NCEPU) North China Electric Power University Institute of Technology for Carbon Neutralization College of ElectricalEnergy and Power EngineeringYangzhou University

In this paper,a new multi-generation system,incorporating solid oxide fuel cell(SOFC),gas turbine(GT),lithium bromide chiller,gas and heat storage components is proposed to address the issues of volatility in user load and energy source input and mismatching between supply and *** dynamic model and control strategy of the system are established,and the system dynamic characteristics in response to solar DNI and external load disturbances are *** system can rapidly adjust the key output and input parameters to realize a new supply-demand balance in a shorter period of time by multiple PID control *** response processes of two combined cooling,heating and power(CCHP) systems with and without gas storage to cope with load changes are *** results show that the CCHP system with gas storage can effectively shorten the response time of load *** solar collector and the SOFC-GT can reach a new equilibrium within a few tens of seconds under the *** response time of the methanol reactor is longer compared to those of solar collector and the SOFC-GT,taking several minutes to *** the cooling and heating load change,the system can adjust the output to the demand value within 500 and 260 seconds.

关键词： dynamic analysis energy storage load-following methanol to hydrogen multi-generation system

来源：评论

学校读者我要写书评

暂无评论

A Valuable and Low-Budget Process Scheme of Equivalized 1 nm Technology Node Based on 2D Materials

引用

Nano-Micro Letters 2025年第8期17卷 294-305页

作者： Yang Shen Zhejia Zhang Zhujun Yao Mengge Jin Jintian Gao Yuhan Zhao Wenzhong Bao Yabin Sun He Tian College of Integrated Circuit Science and Engineering Shanghai Key Laboratory of Multidimensional Information ProcessingEast China Normal UniversityShanghai 200241People’s Republic of China Institute of Microelectronics and Beijing National Research Center for Information Science and Technology(BNRist) Tsinghua UniversityBeijing 100084People’s Republic of China State Key Laboratory of ASIC and System School of MicroelectronicsFudan UniversityShanghai 200433People’s Republic of China Shaoxin Laboratory Shaoxing 312000People’s Republic of China

Emerging two-dimensional(2D)semiconductors are among the most promising materials for ultra-scaled transistors due to their intrinsic atomic-level *** the stacking process advances,the complexity and cost of nanosheet field-effect transistors(NSFETs)and complementary FET(CFET)continue to *** 1 nm technology node is going to be based on Si-CFET process according to international roadmap for devices and systems(IRDS)(2022,https://***/),but not publicly confirmed,indicating that more possibilities still *** miniaturization advantage of 2D semiconductors motivates us to explore their potential for reducing process costs while matching the performance of next-generation nodes in terms of area,power consumption and *** this study,a comprehensive framework is built.A set of MoS2 NSFETs were designed and fabricated to extract the key parameters and *** then for benchmarking,the sizes of 2D-NSFET are scaled to a extent that both of the Si-CFET and 2D-NSFET have the same average device *** these conditions,the frequency of ultra-scaled 2D-NSFET is found to improve by 36%at a fixed power *** work verifies the feasibility of replacing silicon-based CFETs of 1 nm node with 2D-NSFETs and proposes a 2D technology solution for 1 nm nodes,i.e.,“2D eq 1 nm”*** the same time,thanks to the lower characteristic length of 2D semiconductors,the miniaturized 2D-NSFET achieves a 28%frequency increase at a fixed power ***,developing a standard cell library,these devices obtain a similar trend in 16-bit RISC-V *** work quantifies and highlights the advantages of 2D semiconductors in advanced nodes,offering new possibilities for the application of 2D semiconductors in high-speed and low-power integrated circuits.

关键词： Two-dimensional semiconductors 1 nm technology node Nanosheet field-effect transistors Complementary field-effect transistors Horizontal scaling

来源：评论

学校读者我要写书评

暂无评论

Numerical simulation of Streamer Discharge in Transformer Oil Under Various Ionization Energies 19th

Numerical Simulation of Streamer Discharge in Transformer Oi...

引用

19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Bao, Yanyan Liang, Shaobin Wang, Feng Zhang, Guangdong Chen, Jianning Zhou, Yuanxiang State Grid Gansu Electric Power Research Institute Lanzhou730070 China State Key Laboratory of Power System Operation and Control Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789819613786

Discharge in transformer oil is one of the primary causes of transformer failures. The physical mechanisms of oil discharges are not yet fully understood. Scholars have simulated the discharge process with electrodynamics model, but there is limited research on how the ionization energy, which changes due to various factors such as components and temperature of transformer oil, affect the streamer discharge characteristic. To improve the mechanism of discharge in transformer oil, this paper adopts an electrohydrodynamic model to study the impact of different ionization energies on the streamer discharge characteristics of transformer oil, including initiation voltage, discharge voltage, development speed, and electric field strength. When the ionization energy is between 6.1 eV and 8.1 eV, the initiation voltage and discharge voltage increase linearly with the ionization energy. Within the range of 7.1 eV to 8.1 eV, the time in the streamer accumulation phase increases exponentially with the ionization energy, while the streamer development speed decreases. © beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Electrohydrodynamics

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：