检索结果-南通市图书馆

Social-Aware Cooperation Among Mobile Terminals for Wireless Downlink Transmission

在线全文

学校读者我要写书评

暂无评论

China Communications 2015年第9期12卷 1-10页

作者： mao Hongliang Feng Wei Ge ning Tsinghua National Lab for Information Science and Technology Tsinghua University

This paper investigates the social-aware cooperation(SAC) among mobile terminals(MTs), motivated by the fact that modern smart devices have much improved context awareness. Aware of the social ties, the cooperative network contains two layers of property: social and physical. In order to observe how the social awareness benefit the cooperation performance, we first formulate the social ties between MTs into parameters that can describe the cooperative behaviors by taking the mobility feature into account, defined as the conviction-approval-suspicion(CAS) model. Limited by the processing capability, partner selection is of great practical significance. To this end, the social-aware partner selection strategy is analyzed, and a significant superiority is observed compared to social-unaware selection. By analyzing the cooperative throughput, an explicit relationship between the degrees-of-freedom gain and the social-physical property is finally derived. Simulation results validate the theoretical analysis.

关键词： social-aware cooperation partner selection degrees-of-freedom

A variational formula for controlled backward stochastic partial differential equations and some application

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2014年第3期29卷 295-306页

作者： MENG Qing-xin TANG mao-ning Department of Mathematics Huzhou Teachers College School of Mathematical Sciences Fudan University

An optimal control problem for a controlled backward stochastic partial differential equation in the abstract evolution form with a Bolza type performance functional is considered. The control domain is not assumed to be convex, and all coefficients of the system are allowed to be random. A variational formula for the functional in a given control process direction is derived, by the Hamiltonian and associated adjoint system. As an application, a global stochastic maximum principle of Pontraygins type for the optimal controls is established.

关键词： Variational formula stochastic evolution equation backward stochastic evolution equation,stochastic maximum principle spike variation.

中国电网全生命周期碳排放及发电结构转型路径规划研究

在线全文

学校读者我要写书评

暂无评论

气候变化研究进展 2024年第1期20卷 97-106页

作者：田佩宁梁肖官雨捷赵义馨毛保华薛婷北京交通大学综合交通运输大数据应用技术交通运输行业重点实验室北京100044 北京交通大学中国综合交通研究中心北京100044

为评估中国电网全生命周期碳排放强度并研究其转型达峰路径,首先提出全国和各地区电网全生命周期碳排放因子测算模型,测算历年全网全生命周期碳排放强度并分析其影响因素;其次利用情景分析法,分析不同电力转型情景下2022—2060年我国电... 详细信息

为评估中国电网全生命周期碳排放强度并研究其转型达峰路径,首先提出全国和各地区电网全生命周期碳排放因子测算模型,测算历年全网全生命周期碳排放强度并分析其影响因素;其次利用情景分析法,分析不同电力转型情景下2022—2060年我国电网全生命周期碳排放量及其达峰情况。研究表明:(1)2011—2021年我国发电结构转型取得一定成效,全网全生命周期碳排放因子由763.94 g/(kW·h)降至557.73 g/(kW·h);但清洁能源发电减少的碳排放量无法平衡火电增加的碳排放量,全网全生命周期碳排放量仍以年均2.6%的速度增长,由36.1亿t增至46.8亿t。(2)发电结构清洁化和煤电减碳技术进步是降低全网全生命周期碳排放强度的重要举措。(3)快转型情景、基准情景、慢转型情景下我国电网全生命周期碳排放量可分别于2025、2027、2030年达峰,基准情景的碳排放量峰值为52.05亿t,2060年碳排放量为15.78亿t。

关键词：碳达峰全生命周期碳排放因子发电结构情景分析法

基于数值仿真的十字型内高压成形吸能盒优化设计

在线全文

学校读者我要写书评

暂无评论

精密成形工程 2024年第1期16卷 181-191页

作者：李欢李柏週毛成明刘宁刘志波一汽奔腾轿车有限公司长春130012 长春职业技术学院机电学院长春130022

目的实现吸能盒的高碰撞吸能性和低成本化设计。方法以传统的方形冲焊结构吸能盒为研究对象,将其优化为十字型冲焊和十字型内高压成形结构吸能盒,并利用成形数值仿真技术对十字型内高压成形吸能盒进行了成形性研究,还利用碰撞数值仿真... 详细信息

目的实现吸能盒的高碰撞吸能性和低成本化设计。方法以传统的方形冲焊结构吸能盒为研究对象,将其优化为十字型冲焊和十字型内高压成形结构吸能盒,并利用成形数值仿真技术对十字型内高压成形吸能盒进行了成形性研究,还利用碰撞数值仿真技术对3种吸能盒结构进行了碰撞性能研究。结果为提高碰撞吸能性,将传统方形冲焊结构吸能盒的4条主吸能常规传力路径,优化为十字型冲焊和十字型内高压成形结构吸能盒的12条主吸能传力路径,十字型内高压成形吸能盒同时能实现减重6.4%;利用成形数值仿真技术对十字型内高压成形吸能盒进行了成形性研究,结果显示十字型内高压成形吸能盒通过一模十二件生产,能具备优良的可制造性和经济性,相比方形冲焊吸能盒,十字型内高压成形吸能盒可实现降成本5.7%;利用碰撞数值仿真技术对3种吸能盒进行正面100%碰撞和正面40%偏置碰撞性能研究,相比方形冲焊吸能盒,结果显示十字型内高压成形吸能盒吸收能量分别增加12.8%和32.0%,碰撞力峰值分别降低8.4%和39.2%,比吸能分别增加20.5%和41.0%。结论相比方形冲焊吸能盒,十字型内高压成形吸能盒可实现轻量化、低成本和高碰撞吸能性,同时还兼具优良的可制造性的特点。

关键词：吸能盒十字型内高压成形数值仿真碰撞性

维普期刊数据库博看期刊

卫星遥感北大西洋风暴“尤尼斯”生成和发展特征

在线全文

学校读者我要写书评

暂无评论

气象学报 2024年第1期82卷 80-94页

作者：任素玲毛冬艳蒋建莹杨冰韵牛宁国家卫星气象中心(国家空间天气监测预警中心) 北京100081 许健民气象卫星创新中心北京100081 中国遥感卫星辐射测量和定标重点开放实验室北京100081 中国气象局气象干部培训学院北京100081

2022年2月中旬,北大西洋冬季风暴“尤尼斯”(Eunice)给欧洲中、西部带来严重自然灾害。以卫星观测数据为主,研究了“尤尼斯”发生的环境场、卫星水汽图像干侵入特征、对流层中高层位涡强迫对爆发性发展的影响等。结果表明:“尤尼斯”活... 详细信息

2022年2月中旬,北大西洋冬季风暴“尤尼斯”(Eunice)给欧洲中、西部带来严重自然灾害。以卫星观测数据为主,研究了“尤尼斯”发生的环境场、卫星水汽图像干侵入特征、对流层中高层位涡强迫对爆发性发展的影响等。结果表明:“尤尼斯”活动期间,北半球高纬度西半球偏冷、东半球偏暖,极涡偏向北美大陆,北美极区附近平均气温偏低。“尤尼斯”的生成和北美极区附近极涡分裂南下的冷空气沿着西风带东传有关。爆发性发展期间,海平面气压下降率约40 hPa/(24 h),远超爆发性发展指标(24 hPa/(24 h)),且出现在海温正距平区。格陵兰岛南部气旋提供的极区冷空气对爆发性发展尤为重要,该冷空气在北大西洋洋面形成强西北风转偏西风,表现为排列整齐的大范围细胞状积云一直延伸至风暴中心附近,卫星水汽图像上表现为快速增强的干侵入特征,并伴有高位涡异常。发展至最强阶段,高位涡向下伸展,400 hPa最强高位涡区位于风暴中心的正上方,500 hPa以下高位涡向东南方向倾斜,并伴随着对流层中、下层强下沉运动,下沉运动为低空风速增强提供了一定的高空能量来源,高位涡侵入的下方也有利于低层气旋式环流发展。

关键词：风云气象卫星北大西洋冬季风暴“尤尼斯” 卫星洋面风极涡

基于低相干干涉的孔类零件内表面测量系统研究

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

机床与液压 2024年第5期52卷 138-143页

作者：陈骏丁斌毛敏陈宁郭钢祥祖洪飞浙江理工大学机械工程学院浙江杭州310018 南通市计量检定测试所江苏南通226001 浙江省计量科学研究院浙江杭州310018

对孔类零件的内表面进行测量是判断其加工质量和使用寿命的重要手段。针对精密孔类零件内表面测量的需求,提出一种基于低相干干涉的内表面测量及信号处理方法,并搭建了完整的检测系统。对低相干干涉的测量原理进行了分析;搭建了以迈克... 详细信息

对孔类零件的内表面进行测量是判断其加工质量和使用寿命的重要手段。针对精密孔类零件内表面测量的需求,提出一种基于低相干干涉的内表面测量及信号处理方法,并搭建了完整的检测系统。对低相干干涉的测量原理进行了分析;搭建了以迈克尔逊干涉仪为主体,主要包含光源、探测器、数据采集仪、参考臂、样品臂等部分的检测系统;研究了干涉信号滤波以及包络峰值提取算法;最后,通过实验验证了此系统可以表征孔类零件的内部特征,并且其测量精度可达10μm以内。

关键词：孔类零件低相干干涉内表面内径测量

The Galois Correspondence in Field Algebra of G-spin Model

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2005年第4期21卷 673-680页

作者： Li ning JIANG mao Zheng GUO Department of Mathematics Beijing Institute of Technology Beijing 100081. P. R. China LMAM Department of Mathematics Peking University. Beijing 100871. P. R. China

Suppose that G is a finite group and D（G） the double algebra of G. For a given subgroup H of G, there is a sub-Hopf algebra D（G; H） of D（G）. This paper gives the concrete construction of a D（G; H）-invariant su... 详细信息

关键词： G-spin model Double algebra Observable algebra Galois closed

Gabor Order Tracking Filtering Technology in Rotary Machinery

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2010年第5期23卷 613-619页

作者： LI ning QIN Shuren mao Yongfang YANG Jiongming College of Mechanical Engineering Chongqing University Chongqing 400044 China Goldwind Science and Technology Co. Ltd. Wulumuqi 830026 China

Order analysis is one of the most important technique means of condition monitoring and fault diagnosis for rotary *** traditional order analyses usually employ the Vold-Kalman filtering,however this method is confined to the expensive hardware *** paper starts from Gabor transform and applies the Gabor time-frequency filtering to vibration *** order component＇s time-frequency coefficients are extracted by mask *** order component is reconstructed from the obtained *** following four key technologies,such as smoothing rotary speed curve,defining filtering band width,constructing the mask operation matrix and reconstructing signal component,are also deeply ***,the technique to smooth the rotary speed curve based on polynomial approximation,the method to determine filtering band width,the arithmetic to constitute mask array and the iterative algorithm to reconstruct signal based on minimum mean square error are specifically *** 4th order component is successfully gained by using the methods that Gabor time-frequency filter,and the validity and feasibility of this method are *** method can solve the problem of order tracking filter technologies which used to depend on hardware and efficiently improve the accuracy of order analysis.

关键词： Gabor transform order tracking filtering component extraction

Hydrodynamics features of dispersed bubbles in the ventilated wake flow of a cylinder

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2018年第9期26卷 1803-1813页

作者： ning mao Can Kang Wisdom Opare Yang Zhu School of Energy and Power Engineering Jiangsu University Faculty of Engineering Takoradi Technical University

An experimental study was conducted to investigate the 2 D bubbly flow downstream of a cylinder. Sparsely distributed bubbles were produced using the ventilation method. The carrier flow was measured using the particle image velocimetry(PIV) technique. The shadow imaging technique was used to capture instantaneous bubbly flow images. An image-processing code was compiled to identify bubbles in acquired image, calculate the bubble equivalent diameter and the bubble velocity. The effects of Reynolds number and the flow rate of the injected air were considered. The result indicates that the carrier flow is featured by distinct flow structures and the wake region is suppressed as the upstream velocity increases. Regarding the bubbles trapped in the wake flow, the number of small bubbles increases with the upstream velocity. On the whole, the bubble velocity is slightly lower than that of the carrier flow. The consistency between small bubbles and the carrier flow is high in terms of velocity magnitude, which is justified near the wake edge. The difference between the bubble velocity and the carrier flow velocity is remarkable near the wake centerline. For certain Reynolds number, with the increase in the air flow rate, the bubble equivalent diameter increases and the bubble void fraction is elevated.

关键词： Bubble Ventilation Wake flow PIV Photography Bubble size distribution