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海洋条件对波动管热分层效应影响数值分析

原子能科学技术 2021年第S01期55卷 45-51页

作者：刘家仕王建军张蕊哈尔滨工程大学核科学与技术学院黑龙江哈尔滨150001

为探究海洋摇摆条件对核电站稳压器波动管内的热分层现象及流固传热的影响,利用计算流体力学软件FLUENT对三维全尺寸建模的稳压器波动管中发生的热分层现象进行数值模拟研究,并与添加摇摆运动后的管内流动传热现象进行对比分析。与以往... 详细信息

为探究海洋摇摆条件对核电站稳压器波动管内的热分层现象及流固传热的影响,利用计算流体力学软件FLUENT对三维全尺寸建模的稳压器波动管中发生的热分层现象进行数值模拟研究,并与添加摇摆运动后的管内流动传热现象进行对比分析。与以往添加摇摆运动的方法不同,利用FLUENT自带的计算模型即可实现运动过程的模拟。计算结果表明:在该波出瞬态工况下波动管内会出现明显热分层现象,海洋条件的添加可明显改善管内的热分层现象,但可能会带来热振荡影响,摇摆运动下的管内流动传热结果与管内流速、摇摆周期、振幅及摇摆轴均有关。本文结果为后续模拟摇摆条件下热工水力研究提供了一定思路与结果。

关键词：波动管热分层海洋条件数值模拟

Thickness-stretch vibration of a crystal plate carrying a micro-rod array

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Science China(Physics,Mechanics & Astronomy) 2012年第11期55卷 2152-2157页

作者： liu Nan YANG jiashi WANG Ji Department of Engineering Mechanics University of Nebraska Lincoln NE 68588-0526 USA Piezoelectric Device Laboratory School of Mechanical Engineering and Mechanics Ningbo University Ningbo 315211 China

We analyze thickness-stretch vibrations of a plate of hexagonal crystal carrying an array of micro-rods with their bottoms fixed to the top surface of the *** rods undergo longitudinal vibrations when the crystal plate is in thickness-stretch *** plate is modeled by the theory of anisotropic *** rods are modeled by the one-dimensional structural theory for extensional vibration of rods.A frequency equation is obtained and solved using perturbation *** effect of the rod array on the resonant frequencies of the crystal plate is *** results are potentially useful for using thickness-stretch modes of crystal plates to measure the mechanical properties of microrod arrays.

关键词： plate rod vibration sensor

Effects of surface impedance on current density in a piezoelectric resonator for impedance distribution sensing

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Applied Mathematics and Mechanics(English Edition) 2021年第5期42卷 677-688页

作者： Jing liu Jianke DU Ji WANG jiashi YANG Piezoelectric Device Laboratory School of Mechanical Engineering and MechanicsNingbo UniversityNingbo 315211Zhejiang ProvinceChina School of Digital Technology and Engineering Ningbo University of Finance and EconomicsNingbo 315175Zhejiang ProvinceChina Department of Mechanical and Materials Engineering University of Nebraska-LincolnLincolnNE 68588-0526U.S.A.

We study the relationship between the surface mechanical load represented by distributed acoustic impedance and the current density distribution in a shear mode piezoelectric plate acoustic wave resonator.A theoretical analysis based on the theory of piezoelectricity and trigonometric series is *** the specific and basic case when the surface load is due to a local mass layer,numerical results show that the current density concentrates under the mass layer and is sensitive to the physical as well as geometric parameters of the mass layer such as its location and *** provides the theoretical foundation for predicting the surface impedance pattern from the current density distribution,which is fundamental to the relevant acoustic wave sensors.

关键词： piezoelectric resonator sensor plate

Small-signal Analysis of DC Microgrid and Multi-objective Optimization Segmented Droop Control Suitable for Economic Dispatch

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Journal of Modern Power Systems and Clean Energy 2020年第3期8卷 564-572页

作者： Haiyuan liu Yingjie Wang Min Wang Yinan Guo jiashi Wang Gang Shen Guoqiang Liao School of Information and Control Engineering China University of Mining and TechnologyXuzhou 221000China School of Electrical and Power Engineering China University of Mining and TechnologyXuzhou 221000China School of Mechanical Engineering China University of Mining and TechnologyXuzhou 221000China CRRC Zhuzhou Locomotive Co. Ltd.Zhuzhou 412001China

To obtain a larger controllable range of output/input power of droop-control sources,a multi-objective optimization segmented droop control suitable for economic dispatch for a DC microgrid is *** to the small-signal analysis,the worst point of the stability in the droop-control curve is determined through the analysis of a simplified model with multiple droop-control *** considering the worst points of stability as constraints,an elitist non-dominated sorting genetic algorithm is used to search the better turning points of the proposed droop-control curves after obtaining the new rated operation points from the system-layer economic ***,optimization objectives,including the influence of eliminating the line resistance and capacity matching,are considered in the search ***,the simulation results of the DC microgrid simulation model based on RT-Lab are presented to support the stability conclusion and proposed droop control.

关键词： Small signal DC microgrid droop control elitist non-dominated sorting genetic algorithm(NSGA-П)

Deep Learning Models Based on Weakly Supervised Learning and Clustering Visualization for Disease Diagnosis

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Computers, Materials & Continua 2023年第9期76卷 2649-2665页

作者： Jingyao liu Qinghe Feng jiashi Zhao Yu Miao Wei He Weili Shi Zhengang Jiang School of Computer and Information Engineering Chuzhou UniversityChuzhou239000China School of Computer Science and Technology Changchun University of Science and TechnologyChangchun130022China Zhongshan Institute of Changchun University of Science and Technology ZhongshanChina School of Intelligent Engineering Henan Institute of TechnologyXinxiang453003China

The coronavirus disease 2019(COVID-19)has severely disrupted both human life and the health care *** diagnosis and treatment have become increasingly important;however,the distribution and size of lesions vary widely among individuals,making it challenging to accurately diagnose the *** study proposed a deep-learning disease diagnosismodel based onweakly supervised learning and clustering visualization(W_CVNet)that fused classification with ***,the data were *** optimizable weakly supervised segmentation preprocessing method(O-WSSPM)was used to remove redundant data and solve the category imbalance ***,a deep-learning fusion method was used for feature extraction and classification recognition.A dual asymmetric complementary bilinear feature extraction method(D-CBM)was used to fully extract complementary features,which solved the problem of insufficient feature extraction by a single deep learning ***,an unsupervised learning method based on Fuzzy C-Means(FCM)clustering was used to segment and visualize COVID-19 lesions enabling physicians to accurately assess lesion distribution and disease *** this study,5-fold cross-validation methods were used,and the results showed that the network had an average classification accuracy of 85.8%,outperforming six recent advanced classification models.W_CVNet can effectively help physicians with automated aid in diagnosis to determine if the disease is present and,in the case of COVID-19 patients,to further predict the area of the lesion.

关键词： Classification COVID-19 deep learning segmentation unsupervised learning weakly supervised

Functional Safety Development of Vehicle Control System for Electric Four-Wheel Drive Vehicle

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Functional Safety Development of Vehicle Control System for ...

基金投资的差异化竞争策略研究——基于文本分析的视角

2021中国汽车工程学会年会暨展览会

作者： Zhao Yongqiang Li jiashi Zhang Xin Yu Changhong liu Yuanzhi College of Automotive Engineering Jilin university China FAW Corporation Limited New Energy Vehicle Development Institute

The popularity of electric vehicles is increasing day by day,and the development of automotive electronic and electrical systems that meet functional safety requirements is becoming increasingly *** article describes the functional safety development method of the vehicle control system mounted on the electric four-wheel drive vehicle to enable the vehicle control system to achieve the required ASIL,including the item definition,hazard analysis and risk assessment,determination of ASIL and safety goals,functional safety concepts and technical safety concepts. Item definition summarizes the vehicle-level functions undertaken by the vehicle control system,as well as the function-related boundaries and *** HAZOP analysis method is used to identify the possible failure modes of the function,which combined with the possible operating scenarios of the vehicle,then the ASIL that the function needs to achieve and corresponding vehicle-level safety goals are evaluated from three dimensions of severity,exposure and *** functional safety concept takes the torque calculation function of the vehicle control system as an example,combined with the preliminary architectural assumptions,considering that the original torque calculation function is relatively complex,safety requirements of torque monitoring function are gradually derived from the safety goals in order to reduce the ASIL of the original torque calculation *** technical safety concept describes the system-level safety mechanism architecture design method using torque monitoring as an example,according to functional safety requirements,proposes technical safety requirements for hardware and software,including warnings and degraded operation,to guide the subsequent development of software and hardware.

关键词： functional safety VCU system electrical four-wheel drive

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复旦学报（社会科学版） 2021年第6期63卷 189-200页

作者：宋军刘劲吕佳石复旦大学经济学院上海200433 清华大学五道口金融学院北京100083

随着基金市场规模的不断扩大,为增加竞争力,基金公司更加注重基金产品的差异化和多样化。本文对2015~2019年开放式股票基金的招募说明书中的投资策略文本进行分析,构建基于文本的投资策略独特性指标来测度基金投资策略的差异化程度。研... 详细信息

随着基金市场规模的不断扩大,为增加竞争力,基金公司更加注重基金产品的差异化和多样化。本文对2015~2019年开放式股票基金的招募说明书中的投资策略文本进行分析,构建基于文本的投资策略独特性指标来测度基金投资策略的差异化程度。研究结果显示:(1)文本独特性测度能有效识别绿色环保、国企改革、高股息和事件驱动等独特的主题型基金;(2)基金Alpha收益与业绩投资策略的文本独特性负相关,说明差异化高的基金在投资收益外的其他方面满足了投资者效用;(3)基金文本独特性越高,其初始发行募集到的基金份额越多,但基金开始运行后,投资策略的独特性无法吸引更多资金流入;(4)基金的文本独特性越高,资金流对业绩的敏感程度越低,表明文本独特性为基金管理人带来了更稳定的资金流。本文的研究结果为基金公司开展差异化竞争策略提供了支持,不仅有利于其自身风险管理,也有利于形成金融市场的多元特征,促进金融市场的稳定健康发展。

关键词：股票型基金投资策略文本独特性资金流

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北京市住宅租金影响因素空间分异研究

城市规划 2023年第3期47卷 75-84页

作者：刘涛刘嘉杰唐琳陈家实北京大学城市与环境学院

住房租赁市场的健康发展事关居民生活福祉,是住房制度改革的重点内容。以北京市为例,利用GWR模型对住宅租金的空间分异特征和差异化影响因素进行分析。研究发现:(1)北京住宅租金呈现中心-外围梯度递减和北高南低的空间结构特征,同时存... 详细信息

住房租赁市场的健康发展事关居民生活福祉,是住房制度改革的重点内容。以北京市为例,利用GWR模型对住宅租金的空间分异特征和差异化影响因素进行分析。研究发现:(1)北京住宅租金呈现中心-外围梯度递减和北高南低的空间结构特征,同时存在局部高值和低值集中区;(2)中心区位优势、公共交通便捷性,以及商业、教育、游憩等邻里环境的质量与可达性对住宅租金产生显著的积极影响;(3)各因素对租金的影响作用都存在较大的空间分异,中心区位条件与就业机会分布叠加对住宅租金产生影响,地铁分布的积极影响突出体现于郊区,邻里环境的影响在局部生活圈内呈现强空间依赖性。最后从资源均衡布局和人群需求的角度探讨了实证结果的规划意义。

关键词：住宅租金空间分异邻里环境地理加权回归模型北京

基于Fourier-Legendre级数展开的主动配电网储能容量优化

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电网技术 2017年第4期41卷 1123-1131页

作者：韩为超刘俊勇刘友波向月杨嘉湜陈龙李斌四川大学电气信息学院四川省成都市610065 四川省电力公司四川省成都市610061

主动配电网中储能运行过程具有明显的时序特性,尤其在细分运行时段或考虑储能组数配置的优化问题中,决策变量的维数急剧增加,加剧了模型问题求解难度。针对这一问题,提出一种对储能的能量状态(state of energy,SOE)进行Fourier-Legendr... 详细信息

主动配电网中储能运行过程具有明显的时序特性,尤其在细分运行时段或考虑储能组数配置的优化问题中,决策变量的维数急剧增加,加剧了模型问题求解难度。针对这一问题,提出一种对储能的能量状态(state of energy,SOE)进行Fourier-Legendre级数展开的容量优化方法。首先,通过Fourier-Legendre级数展开的方法建立储能的模型,优化展开项的系数,由此得储能SOE的连续化函数表达式。其次,考虑分布式电源(distributed generation,DG)出力不确定性,建立了同时以DG消纳和削峰填谷为目标的机会约束模型。由此,求解出主动配电网不同运行状况下储能充放电功率和储能电池容量。通过算例验证了所提方法的快速性和有效性,并分析了储能电池容量、风光渗透率、网络电压分布状况等的相互作用。

关键词： Fourier-Legendre级数储能不确定性主动配电网优化