检索结果-南通市图书馆

Analyses of dynamic characteristics of a fluid-filled thin rectangular porous plate with various boundary conditions

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2017年第1期30卷 87-97页

作者： yu xiang Automotive and Transportation Engineering Collage Guangxi University of Science and Technology Liuzhou 545006 China Guangxi Key Laboratory of Automobile Components and Vehicle Technology Guangxi University of Science and Technology Liuzhou 545006 China

Based on the classical theory of thin plate and Biot theory, a precise model of the transverse vibrations of a thin rectangular porous plate is proposed. The first order differential equations of the porous plate are derived in the frequency domain. By considering the coupling effect between the solid phase and the fluid phase and without any hypothesis for the fluid displacement, the model presented here is rigorous and close to the real materials. Owing to the use of extended homogeneous capacity precision integration method and precise element method, the model can be applied in higher frequency range than pure numerical methods. This model also easily adapts to various boundary conditions. Numerical results are given for two different porous plates under different excitations and boundary conditions.

关键词： Thin rectangular porous plate Blot theory Vibration First order differential equations Extended homogeneous capacity high precision integration method

Detection and Estimation of False Data Injection Attacks for Load Frequency Control Systems

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2022年第4期10卷 861-870页

作者： Jun Ye xiang yu Hangzhou Innovation Institute Beihang UniversityHangzhouChina School of Automation Science and Electrical Engineering Beihang UniversityBeijingChina

False data injection attacks(FDIAs)against the load frequency control(LFC)system can lead to unstable operation of power *** this paper,the problems of detecting and estimating the FDIAs for the LFC system in the presence of external disturbances are ***,the LFC system model with FDIAs against frequency and tie-line power measurements is ***,a design procedure for the unknown input observer(UIO)is presented and the residual signal is generated to detect the *** UIO is designed to decouple the effect of the unknown external disturbance on the residual *** that,an attack estimation method based on a robust adaptive observer(RAO)is proposed to estimate the state and the FDIAs *** order to improve the performance of attack estimation,the H¥technique is employed to minimize the effect of external disturbance on estimation errors,and the uniform boundedness of the state and attack estimation errors is proven using Lyapunov stability ***,a two-area interconnected power system is simulated to demonstrate the effectiveness of the proposed attack detection and estimation algorithms.

关键词： External disturbance false data injection attacks load frequency control robust adaptive observer unknown input observer

Design of passive fault-tolerant flight controller against actuator failures

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第1期28卷 180-190页

作者： yu xiang Zhang Youmin Department of Mechanical and Industrial Engineering Concordia University

The problem of designing passive fault-tolerant flight controller is addressed when the normal and faulty cases are prescribed. First of all, the considered fault and fault-free cases are formed by polytopes. As considering that the safety of a post-fault system is directly related to the maximum values of physical variables in the system, peak-to-peak gain is selected to represent the relationships among the amplitudes of actuator outputs, system outputs, and reference commands. Based on the parameter dependent Lyapunov and slack methods, the passive fault-tolerant flight controllers in the absence/presence of system uncertainty for actuator failure cases are designed, respectively. Case studies of an airplane under actuator failures are carried out to validate the effectiveness of the proposed approach

关键词： actuator tolerant uncertainty prescribed addressed nominal matrices validate outputs designing

Remarks on the Extremal Functions for the Moser-Trudinger Inequality

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2006年第2期22卷 545-550页

作者： yu xiang LI Department of Mathematical Science Tsinghua University

We will show in this paper that if A is very close to 1, thenI（M,λ,m） =supu∈H0^1,n（m）,∫m｜△↓u｜^ndV=1∫Ω（e^αn｜u｜^n/（n-1）-λm∑k=1｜αnun/（n-1）｜k/k!）dVcan be attained, where M is a compact-manifold with boundary. This result gives a counter-example to the conjecture of de Figueiredo and Ruf in their paper titled ＂On an inequality by Trudinger and Moser and related elliptic equations＂（Comm. Pure. Appl. Math., 55, 135-152, 2002）.

关键词： Moser-Trudinger inequality extremal function

Modeling method and preliminary model of Asteroid Toutatis from Chang'E-2 optical images

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2014年第3期30卷 310-315页

作者： xiang-yu Li Dong Qiao School of Aerospace Engineering Beijing Institute of Technology Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education

Shape modeling is fundamental to the analysis of dynamic environment and motion around asteroid. Chang＇E- 2 successfully made a flyby of Asteroid 4179 Toutatis and obtained plenty of high-resolution images during the mis- sion. In this paper, the modeling method and preliminary model of Asteroid Toutatis are discussed. First, the optical images obtained by Chang＇E-2 are analyzed. Terrain and silhouette features in images are described. Then, the modeling method based on previous radar model and preliminary information from optical images is proposed. A preliminary polyhedron model of Asteroid Toutatis is established. Finally, the spherical harmonic coefficients of Asteroid Toutatis based on the polyhedron model are obtained. Some parameters of model are analyzed and compared. Although the model proposed in this paper is only a preliminary model, this work offers a valuable reference for future high-resolution models.

关键词： Chang'E-2 Asteroid Toutatis Shape modeling.Polyhedron method

Evaluation of pelvic lymph node coverage of conventional radiotherapy fields based on bony landmarks in Chinese cervical cancer patients using CT simulation

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第9期10卷 683-688页

作者： xiang ZHANG Hua yu Department of Gynecologic Oncology Zhejiang Cancer Hospital Hangzhou 310022 China

Objective： To evaluate the pelvic lymph node coverage of conventional pelvic fields based on bony landmarks in Chinese patients with cervical cancer by using computed tomography （CT） simulation images to contour pelvic vessels as substitutes for lymph nodes location. Methods： A retrospective review of CT simulation images and conventional pelvic radiation planning data sets was performed in 100 patients with cervical cancer at the International Federation of Gynecology and Obstetrics （FIGO） Stage liB to IIIB in our hospital. Pelvic arteries were contoured on CT simulation images, and the outlines of conventional pelvic fields were drawn as defined by the gynecologic oncology group （GOG） after hiding the contours. The distances between the following vessel contours and field borders were measured： D1, the superior border of the anterior/posterior （AP） field and the bifurcation of abdominal aorta; D2, the ipsilateral border of the AP field and the distal end of external iliac artery; and D3, the anterior border of the lateral （LAT） field and the distal end of the external iliac artery. The distances were recorded as positive values if the measuring point was within the conventional pelvic fields, or they were recorded as negative values. Lymph nodes coverage was considered adequate when D1≥0 mm, D2〉17 mm or D3≥7 mm. Results： All patients had at least 1 inadequate margin, 97 patients （97.0%） had 2, and 22 patients （22.0%） had all the 3. On the AP field, 95 patients （95%） had the measuring point, the bifurcation of the abdominal aorta, out of the field （D1〈0 mm）, and all the patients had a distance less than 17.0 mm between the distal end of the external iliac artery and ipsilateral border （D2〈1 7.0 mm）. On the LAT field, 24 patients （24%） had a distance less than 7.0 mm between the distal end of the external iliac artery and anterior border （D3〈7.0 mm）. Conclusion： We observed that conventional pelvic fields based on bony landmarks provided inadequate coverage of pelvi

关键词： Cervical cancer Radiotherapy planning Computed tomography (CT) simulation Lymph nodes

负载纳米钽的液晶显示光固化聚乳酸支架制备及促成骨性能

在线全文

学校读者我要写书评

暂无评论

中国组织工程研究 2025年第4期29卷 670-677页

作者：李明哲叶翔凌王冰余翔南阳医学高等专科学校针灸骨伤系河南省南阳市473000 广州中医药大学东莞医院广东省东莞市523888 广州中医药大学第一附属医院广东省广州市510405 广东省中医临床研究院广东省广州市510405

背景:聚乳酸因具有良好的生物相容性和可控的降解速率在生物医学工程中得到了广泛应用,然而存在机械强度低和生物活性不足等缺陷,限制了其在骨组织工程中的进一步应用。目的:构建聚乳酸/聚多巴胺/钽(PLA/PDA/Ta)骨组织工程支架,探究其... 详细信息

背景:聚乳酸因具有良好的生物相容性和可控的降解速率在生物医学工程中得到了广泛应用,然而存在机械强度低和生物活性不足等缺陷,限制了其在骨组织工程中的进一步应用。目的:构建聚乳酸/聚多巴胺/钽(PLA/PDA/Ta)骨组织工程支架,探究其生物安全性和体外促成骨性能。方法:利用液晶显示光固化技术制备具有多孔结构的聚乳酸(PLA)支架,将PLA支架分别浸泡在多巴胺溶液与多巴胺-纳米钽混合溶液中分别制备聚乳酸/聚多巴胺(PLA/PDA)支架、PLA/PDA/Ta支架,表征支架的微观形貌与水接触角。将MC3T3-E1细胞分别与PLA、PLA/PDA、PLA/PDA/Ta支架共培养,进行CCK-8检测与活/死细胞染色;成骨诱导分化后,进行碱性磷酸酶、茜素红染色及成骨基因检测。结果与结论:①扫描电镜下可见3种支架均具有互连的多孔三维结构,平均孔径为200μm;PLA/PDA/Ta支架的水接触角低于PLA、PLA/PDA支架(P<0.05);②CCK-8检测显示,相较于PLA、PLA/PDA支架,PLA/PDA/Ta支架可促进细胞的增殖(P<0.05);活/死细胞染色显示3组细胞增殖良好;③碱性磷酸酶与茜素红染色显示,相较于PLA、PLA/PDA支架,PLA/PDA/Ta支架可促进细胞碱性磷酸酶的表达与矿化结节形成;RT-qPCR检测显示,相较于PLA、PLA/PDA支架,PLA/PDA/Ta支架可促进细胞骨形态发生蛋白、Runx-2及Ⅰ型胶原mRNA的表达(P<0.05,P<0.01);④结果表明,PLA/PDA/Ta支架具有优异的促细胞增殖与成骨活性。

关键词：液晶显示光固化打印聚乳酸聚多巴胺纳米钽 MC3T3-E1细胞骨组织工程支架

Potential Effects of the COVID-19 Pandemic on the Developing Brain

在线全文

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2023年第2期39卷 343-347页

作者： xiang yu Xiu Xu State Key Laboratory of Membrane Biology School of Life SciencesPeking-Tsinghua Center for Life Sciencesand Peking University McGovern InstitutePeking UniversityBeijing 100871China Autism Research Center of Peking University Health Science Center Beijing 100191China Chinese Institute for Brain Research Beijing 102206China Department of Child Healthcare Children’s Hospital of Fudan UniversityShanghai 201102China

By now,the COVID-19 pandemic has affected all corners of the world for over two *** years constitutes 4%of the life experience of a 50-year-old,or 50%of the life experience of a ***,in terms of the sheer proportion of... 详细信息

关键词： has she ID

Optimal constant in an L^2 extension problem and a proof of a conjecture of Ohsawa

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

Science China Mathematics 2015年第1期58卷 35-59页

作者： GUAN Qi'An ZHOU xiang yu Beijing International Center for Mathematical Research Peking University School of Mathematical Sciences Peking University Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of Sciences Hua Loo-Keng Key Laboratory of Mathematics Chinese Academy of Sciences

In this paper,we solve the optimal constant problem in the setting of Ohsawa’s generalized L2extension *** applications,we prove a conjecture of Ohsawa and the extended Suita conjecture,we also establish some relatio... 详细信息

关键词： L2 extension theorem optimal L2 estimate Bergman kernel a conjecture of Ohsawa extendedSuita conjecture