检索结果-南通市图书馆

Science China(Information Sciences) 2024年第7期67卷 224-239页

作者： Zhijia ZHAO Jiale WU Zhijie lIU We HE C.l.Philip CHEN School of Mechanical and Electrical Engineering Guangzhou University School of Intelligence Science and Technology and Key laboratory of Intelligent Bionic Unmanned Systems of Ministry of Education University of Science and Technology Beijing School of Computer Science and Engineering South China University of Technology Pazhou lab

In this study, an adaptive neural network(nn) control is proposed for nonlinear two-degree-offreedom(2-DOF) helicopter systems considering the input constraints and global prescribed ***, radial basis function nn(RBFnn) is employed to estimate the unknown dynamics of the helicopter system. Second, a smooth nonaffine function is exploited to approximate and address nonlinear constraint functions. Subsequently, a new prescribed function is proposed, and an original constrained error is transformed into an equivalent unconstrained error using the error transformation and barrier function transformation methods. The analysis of the established lyapunov function proves that the controlled system is globally uniformly bounded. Finally, the simulation and experimental results on a constructed Quanser's test platform verify the rationality and feasibility of the proposed control.

关键词： adaptive nn control 2-DOF helicopter global prescribed performance input constraints

Effect of extraction method on Mycochemicals and Proximate composition of Pyrrhoderma noxium(Corner)***&***,(Hymenochaetales,Basidiomycota)

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Studies in Fungi 2019年第1期4卷 223-229页

作者： Nagadesi PK Naveen Babu D Suneetha nn Prasad KSM Devi PP Department of Botany P.G.BlockAndhra Loyola CollegeNear GunadalaVijayawada-8Andhra PradeshIndia Department of Biochemistry R&D WingSt.Joseph Dental CollegeDuggiralaEluruAndhra PradeshIndia

Several medicines obtained from Pyrrhoderma mushrooms are widely used against several diseases throughout the ***,in preparation of crude drugs/folk medicines of mushroom *** noxium collected from Krishna district,Andhra Pradesh,India was studied and identified *** present work aims to test the presence of Mycochemicals and proximate composition for standardization of powder of *** solvents used for extraction and method of extraction played a vital role on mycochemical and proximate composition of *** *** maceration water bath assisted extraction method is the best extraction method compared to maceration and Reflux extraction methods for all parameters studied in this *** present study shows the extraction method and type of solvent influencing the presence of mycochemical composition like alkaloids,carbohydrates,phenols,flavonoids,tannins,terpenoids,diterpenoids,and anthocyanin in hymenochaetales *** proximate composition evaluation is very much useful for standardisation of *** in powder *** will help to identify the genuine species and check for adulteration of powder available commercially.

关键词： Extraction type Hymenophore Phytochemicals Phenotypical Phellinus noxius

模块化多电平有源电力滤波器误差反馈模型预测控制策略

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

电力建设 2024年第3期45卷 107-115页

作者：刘琛吕世轩刘宗沛郑丽君太原理工大学电气与动力工程学院太原市030024

有源电力滤波器(active power filter, APF)应用在高电压大容量场合需要采用模块化多电平换流器(modular multilevel converter, MMC)结构,然而,由于系统阻抗等参数与实际参数存在偏差,导致传统模型预测控制(model predictive control, ... 详细信息

有源电力滤波器(active power filter, APF)应用在高电压大容量场合需要采用模块化多电平换流器(modular multilevel converter, MMC)结构,然而,由于系统阻抗等参数与实际参数存在偏差,导致传统模型预测控制(model predictive control, MPC)输出预测值失去最优性,最终影响MMC-APF补偿效果。为此,针对MMC-APF提出一种误差反馈模型预测控制策略,通过结合MPC与电压排序算法将每个控制周期开关状态计算量从C2nn次降低至N+1次,并分别设计输出补偿谐波控制、环流抑制以及子模块电容能量均衡控制的评价函数,同时引入误差反馈对预测值进行修正,降低了预测值与输出值之间的稳态跟踪误差,从而提高了网侧电流谐波补偿效果,并实现对环流的有效抑制以及子模块电容能量均衡。在Matlab/Simulink仿真平台进行了验证,仿真实验结果表明:采用所提控制策略,MMC-APF能够将网侧电流谐波含量由27.6%降至0.2%,证明了所提控制策略的正确性及有效性。

关键词：模块化多电平变换器(MMC) 有源电力滤波器(APF) 误差反馈模型预测控制(MPC)

Short range correlations in nuclei

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2010年第9期34卷 1224-1228页

作者： l.B.Weinstein Physics Department Old Dominion University

Studying nucleon-nucleon （nn） correlated pairs will teach us a great deal about the high momentum part of the nuclear wave function,the short range part of the nn interaction,and the nature of cold dense nuclear *** correlations are similar in all nuclei,differing only in *** momentum nucleons,p 〉p fermi,all have a correlated partner with approximately equal and opposite *** pair relative momenta of 300 〈prel 〈500 MeV/c,these correlated pairs are dominated by tensor *** is shown by the dominance of pn over pp pairs at pair total momentum and by the parity of pn to pp pairs at large pair total momentum.

关键词： correlations nucleon momentum distributions tensor correlations

Decomposition of methylamine on Mo(100) surface: A DFT study

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2012年第2期21卷 132-137页

作者： Jianhong liu Cunqin lü Dongli Du Yong Guo College of Chemistry and Chemical Engineering Shanxi Datong UniversityDatong 037009ShanxiChina

The initial decomposition of methylamine on Mo（100） surface has been investigated by self-consistent （GGA-PW91） density functional theory combined with periodic slab model. The adsorption energies of possible species and the activation energies for possible elementary reactions involved are obtained in the present work. Our results indicate that the barriers decreased with the order of C-nn-HC-H. In addition, metastable adsorption of the abstracted hydrogen atom on the hollow site in the final state is also considered for the N-H and C-H bond breaking. For the C-H bond cleavage, the reaction barrier that the abstracted hydrogen located on the hollow site in the final state is lower than that on the bridge site. However, for the N H bond breaking, the barriers are alike for the abstracted hydrogen on both hollow and bridge sites in the final state.

关键词： methylamine decomposition Mo(100) DFT calculations slab model

Performance analysis of fuzzy BlS using different cluster methods for classification

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2021年第4期64卷 232-234页

作者： Shuang FENG C.l.Philip CHEN School of Applied Mathematics Beijing Normal University Faculty of Science and Technology University of Macau

Dear editor,Neural networks (nns) and fuzzy systems are commonly used computational intelligence techniques, each with their own merits in terms of applications. The integration of nns and fuzzy systems, which leads to a hybrid framework known as neuro-fuzzy systems, inherits the useful properties of its constituents:the learning power of an nn and the knowledge representation of a fuzzy inference system,

关键词： Information Systems and Communication Service

活体肾脏捐献者发生妊娠期高血压及子痫前期的风险

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中华高血压杂志 2015年第7期23卷 682-684页

作者： Garg AX Nevis IF McArthur E Sontrop JM Koval JJ lain nn Hildebrand AM Reese PP Storsley l Gill JS Segev Dl Habbous S Bugeja A Knoll GA Dipchand C Cuadros MM lentine Kl 《中华高血压杂志》编辑部

每年全球活体肾脏捐献者〉27 000人,其中大部分为女性[1]。年轻女性捐献者常会询问肾脏切除是否对其日后怀孕造成影响[2]。目前多个关于肾脏捐献者与非捐献者的非妊娠期高血压患病风险差异性的研究结果彼此冲突。

关键词：妊娠期高血压肾脏切除患病风险捐献者子痫前期活体女性

ON KANTOROVICH-STIElTJES OPERATORS

在线全文

学校读者我要写书评

暂无评论

Analysis in Theory and Applications 1993年第3期9卷 53-60页

作者： l.Szili 1. Department of Numerical Analysis Loránd E?tv?s University Bogdánfy u. 10/B H-1117 Budapest Hungary

let ν be a finite Borel measure on[0,1]The Kantorovich-Stieltjes polynomials are de- fined by K_n ν=(n+1)N_(k,n)(nn), where N_(k,n)(x)=x^k(1-x)^(n-k)(x[0,1],k=1,2,…,n)are the basic Bernstein polynomials and I_(k,n):=[k/(n+1),(k+1)/(n+1)](k=0,1,…,n;nn).We prove that the maximal operator of the sequence(K_n)is of weak type and the sequence of polynomials(K_n ν)con- verges ***[0,1]to the Radon-Nikodym derivative of the absolutely continuous part of

关键词： ON KANTOROVICH-STIElTJES OPERATORS

国产雷帕霉素药物洗脱支架和紫杉醇药物洗脱球囊对冠心病患者近期预后的影响

在线全文

学校读者我要写书评

暂无评论

河南医学研究 2024年第18期33卷 3291-3295页

作者：王卓吕风华司澳洋新乡医学院第一附属医院心血管内科河南新乡453000

目的探究国产雷帕霉素药物洗脱支架与紫杉醇药物洗脱球囊对冠心病患者经皮冠状动脉介入术(PCI)近期预后的影响。方法研究对象为2020年3月至2021年3月在新乡医学院第一附属医院接受介入治疗的冠心病患者,回顾性选取56例接受国产雷帕霉素... 详细信息

目的探究国产雷帕霉素药物洗脱支架与紫杉醇药物洗脱球囊对冠心病患者经皮冠状动脉介入术(PCI)近期预后的影响。方法研究对象为2020年3月至2021年3月在新乡医学院第一附属医院接受介入治疗的冠心病患者,回顾性选取56例接受国产雷帕霉素药物洗脱支架置入的患者作为药物洗脱支架组,另选取57例接受紫杉醇药物洗脱球囊扩张的患者作为药物球囊洗脱组,均进行1 a随访,对术前术后1周时的心率变异性指标、冠状动脉造影结果参数、靶病变管腔直径及狭窄情况及血清激肽释放酶1(KlK1)、基质金属蛋白酶组织抑制因子-1(TIMP-1)、内皮素-1(ET-1)、一氧化氮(NO)水平进行比较,并比较术后1 a内发生不良心血管事件情况。结果两组术前和术后1周的正常窦性RR间期标准差(SDnn)、均值标准差(SDAnn)、相邻nn间期之间差大于50 ms数占比(pnn50)、靶病变参考血管直径、最小管腔直径、直径狭窄率组间差异无统计学意义(P>0.05),术后1周两组SDnn、SDAnn、pnn50、靶病变最小管腔直径指标均较术前升高(P0.05)。术前,两组患者的KlK1、TIMP-1、ET-1、NO水平差异无统计学意义(P>0.05),术后1周两组KlK1、NO水平较术前升高且研究组更高,TIMP-1、ET-1水平较术前降低且研究组更低(P0.05)。结论在对冠心病患者进行PCI治疗时,使用国产雷帕霉素药物洗脱支架与紫杉醇药物洗脱球囊近期预后方面的效果相似,且不会增加患者预后不良风险。

关键词：冠心病经皮冠状动脉介入术国产雷帕霉素紫杉醇药物洗脱支架药物洗脱球囊近期预后

Neural Network-Based Second Order Reliability Method(nnBSORM)for laminated Composite Plates in Free Vibration

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

Computer Modeling in Engineering & Sciences 2018年第4期115卷 105-129页

作者： Mena E.Tawfik Peter l.Bishay Edward E.Sadek Aerospace Engineering Department Faculty of EngineeringCairo UniversityEgypt Mechanical and Aerospace Engineering Department Rutgersthe State University of New JerseyNew BrunswickNJUSA Mechanical Engineering Department College of Engineering and Computer ScienceCalifornia State UniversityNorthridgeCAUSA.

Monte Carlo Simulations(MCS),commonly used for reliability analysis,require a large amount of data points to obtain acceptable accuracy,even if the Subset Simulation with Importance Sampling(SS/IS)methods are *** Second Order Reliability Method(SORM)has proved to be an excellent rapid tool in the stochastic analysis of laminated composite structures,when compared to the slower MCS ***,SORM requires differentiating the performance function with respect to each of the random variables involved in the *** most suitable approach to do this is to use a symbolic solver,which renders the simulations very slow,although still faster than ***,the inability to obtain the derivative of the performance function with respect to some parameters,such as ply thickness,limits the capabilities of the classical *** this work,a Neural Network-Based Second Order Reliability Method(nnBSORM)is developed to replace the finite element algorithm in the stochastic analysis of laminated composite plates in free *** of the ability to obtain expressions for the first and second derivatives of the nn system outputs with respect to any of its inputs,such as material properties,ply thicknesses and orientation angles,the need for using a symbolic solver to calculate the derivatives of the performance function no longer *** proposed approach is accordingly much faster,and easily allows for the consideration of ply thickness *** present analysis showed that dealing with ply thicknesses as random variables results in 37%increase in the laminate’s probability of failure.

关键词： Reliability analysis artificial neural network composite laminates subset simulation importance sampling Monte Carlo