检索结果-南通市图书馆

Observer-based Multirate Feedback Control Design for Two-time-scale System

International Journal of Automation and computing 2021年第6期18卷 1007-1016页

作者： Ravindra Munje wei-dong zhang Department of Electrical Engineering K.K.Wagh Institute of Engineering Education and ResearchNashik 422003India Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China

The use of a lower sampling rate for designing a discrete-time state feedback-based controller fails to capture information of fast states in a two-time-scale system, while the use of a higher sampling rate increases the amount of computation considerably. Thus,the use of single-rate sampling for systems with slow and fast states has evident limitations. In this paper, multirate state feedback(MRSF) control for a linear time-invariant two-time-scale system is proposed. Here, multirate sampling refers to the sampling of slow and fast states at different sampling rates. Firstly, a block-triangular form of the original continuous two-time-scale system is constructed. Then, it is discretized with a smaller sampling period and feedback control is designed for the fast subsystem. Later, the system is block-diagonalized and equivalently represented into a system with a higher sampling period. Subsequently, feedback control is designed for the slow subsystem and overall MRSF control is derived. It is proved that the derived MRSF control stabilizes the full-order system. Being the transformed states of the original system, slow and fast states need to be estimated for the MRSF control ***, a sequential two-stage observer is formulated to estimate these states. Finally, the applicability of the design method is demonstrated with a numerical example and simulation results are compared with the single-rate sampling method. It is found that the proposed MRSF control and observer designs reduce computations without compromising closed-loop performance.

关键词： Feedback control multirate sampling sequential observer two-stage design two-time-scale system

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Bi-dimension decomposed hidden Markov models for multi-person activity recognition

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 810-819页

作者： wei-dong zhang Feng CHEN Wen-li XU Department of Automation Tsinghua University Beo'ing 100084 China

We present a novel model for recognizing long-term complex activities involving multiple persons. The proposed model, named ‘decomposed hidden Markov model’ (DHMM), combines spatial decomposition and hierarchical abstraction to capture multi-modal, long-term dependent and multi-scale characteristics of activities. Decomposition in space and time offers conceptual advantages of compaction and clarity, and greatly reduces the size of state space as well as the number of parameters. DHMMs are efficient even when the number of persons is variable. We also introduce an efficient approximation algorithm for inference and parameter estimation. Experiments on multi-person activities and multi-modal individual activities demonstrate that DHMMs are more efficient and reliable than familiar models, such as coupled HMMs, hierarchical HMMs, and multi-observation HMMs.

关键词： Multi-channel setting Hierarchical modeling Hidden Markov model Activity recognition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Distributed H_∞ PID Feedback for Improving Consensus Performance of Arbitrary-delayed Multi-agent System

引用

International Journal of Automation and computing 2014年第2期11卷 189-196页

作者： Lin-Lin Ou Jun-Jie Chen dong-Mei zhang Lin-zhang wei-dong zhang Department of Automation Zhejiang University of Technology Department of Automation Shanghai Jiaotong University

The H∞ proportional-integral-differential(PID) feedback for arbitrary-order delayed multi-agent system is investigated to improve the system performance. The closed-loop multi-input multi-output(MIMO) control framework with the distributed PID controller is firstly described for the multi-agent system in a unified way. Then, by using the matrix theory, the prescribed H∞performance criterion of the multi-agent system is shown to be equivalent to several independent H∞ performance constraints of the single-input single-output(SISO) subsystem with respect to the eigenvalues of the Laplacian matrix. Subsequently, for each subsystem,the set of the PID controllers satisfying the required H∞ performance constraint is analytically characterized based on the extended Hermite-Biehler theorem. Finally, the three-dimensional set of the decentralized H∞ PID control parameters is derived by finding the intersection of the H∞ PID regions for all the decomposed subsystems. The simulation results reveal the effectiveness of the proposed method.

关键词： Multi-agent system proportional-integral-differential(PID) controller H∞ performance index parametric space consensus.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Cavity optomechanics with cold atomic gas

引用

Frontiers of physics 2011年第3期6卷 237-250页

作者： Ke-ye zhang Lu ZHOU Guang-jiong dong wei-ping zhang State Key Laboratory of Precision Spectroscopy Department of Physics East China Normal University Shanghai 200062 China

We present a tutorial review on the topics related to current development in cavity optomechanics, with special emphasis on cavity optomechanical effects with ultracold gases, Bose-Einstein condensates, and spinor Bos-Einstein condensates. Topics including the quantum model and nonlinearity of the cavity optomechanics, the principles of optomechanical cooling, radiation-pressure-induced nonlinear states, the chaotic dynamics in a condensate-mirror-hybrid optomechanical setup, and the spin-mixing dynamics controlled by optical cavities are covered.

关键词： cavity optomechanics Bose-Einstein condensate spinor Bose-Einstein condensate,optical bistability

来源：

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

Celastrol as a tool for the study of the biological events of metabolic diseases

引用

Science China Chemistry 2019年第4期62卷 409-416页

作者： Gongcai Lan Jie zhang Wenbo Ye Fan Yang Ang Li weiwei He wei-dong zhang Guangdong Pharmaceutical University Shanghai Key Laboratory of New Drug Design School of Pharmacy East China University of Science and Technology State Key Laboratory of Bioorganic and Natural Products Chemistry Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Department of Phytochemistry School of Pharmacy Second Military Medical University State Key Laboratory of Innovative Natural Medicine and Traditional Chinese Medicine Injections Jiangxi Qingfeng Pharmaceutical Co.Ltd.

Celastrol is a pentacyclic triterpenoid isolated from Tripterygium wilfordii that has long been used in traditional Chinese medicine for treating rheumatoid arthritis. Previous studies showed that celastrol possessed diverse biological activities, including anti-inflammatory and anticancer properties. Interestingly, most recent literatures revealed the important role of celastrol against metabolic disorders. Herein, we provide an overview of the modes of action of celastrol for combating metabolic diseases such as obesity and type 2 diabetes. The anti-obesity effect of celastrol results from relieving endoplasmic reticulum stress in hypothalamus, regulating HSF1-PGC1α axis in the adipose tissue and muscle, and alleviating inflammation via Nur77 mediated autophagy. Celastrol also reverses insulin resistance via NF-κB signaling pathway to protect against type 2 diabetes.

关键词： celastrol obesity type 2 diabetes endoplasmic reticulum stress inflammation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhancement of CD4^+ T cell activities and modulation of Th1/Th2 lineage development in radiated tumor-bearing rats treated with male zooid of Antheraea pernyi extracts

引用

World Journal of Gastroenterology 2008年第13期14卷 2094-2099页

作者： Wen-Hua Zhao Ling Li Bo zhang wei-dong zhang Min Zong Ji-dong Tang Hong-Yu zhang Sheng Li Shandong Tumor Hospital Jinan 250117 Shandong Province China Shandong Academy of Medical Sciences Jinan 250062 Shandong Province China Institute of of Basic Medicine Shandong Academy of Medical Sciences Jinan 250062 Shandong Province China Qilu Hospital of Shandong University Jinan 250011 Shandong Province China

AIM： To investigate whether supplementation of male zooid of Antheraea pernyi extracts （MZAPE） could enhance immune function of radiated tumor-bearing rats. METHODS： Eighty male Wistar rats were randomly divided into a control group, a simple radiation group, a MZAPE group, and a radiation plus MZAPE group. With the tumor model established by implanting Walker-256 ascites tumor cells, tumor weight and tumor control rate were calculated. The rats in the simple radiation and radiation plus MZAPE groups were underwent to radiation at 10 Gy within 2 d. In the MZAPE and radiation plus MZAPE groups, the MZAPE was gavaged at a dose of 16.53 mg/kg once a day for 7 d. T cell subsets in peripheral blood were determined by flow cytometry and the expression of IL-2, IFN-γ, IL-4 and IL-10 in sera were determined by ELISA on the 8th d. RESULTS： The tumor weight of simple radiation group, MZAPE group and radiation plus MZAPE group was lower than that of control group （P 〈 0.01） and tumor control rates were 63.08% ± 6.43%, 69.86%± 7.12% and 35.30% ± 7.67%, respectively. CD^4＋ T and CD^8＋ T cells in the peripheral blood of the simple radiation group were fewer than in control group. In the MZAPE and radiation plus MZAPE groups, the number of CD^4＋ T cells was higher while CD^8＋ T cells was lower than in the control and simple radiation groups. Expression of IL-2 and INF-y in the radiation group was lower than in control group, and significantly enhanced during MZAPE therapy （P 〈 0.05）. Expression of IL-4 and IL-10 in the radiation group had no significant changes compared with the control group, and decreased significantly after MZAPE treatment （P 〈 0.01）. CONCLUSION： MZAPE administration may help improve the immune function of the radiated tumor-bearing rats and reverse the radiation-induced immune inhibition by promoting the proliferation of T helper cells and inducing the transdifferentiation from Th2 to Th1.

关键词： Antheraea pernyi Male zooid Rats Radiotherapy Immune suppression

来源：

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

A special recurrent pattern in small hepatocellular carcinoma after treatment:Bile duct tumor thrombus formation

引用

World Journal of Gastroenterology 2011年第43期17卷 4817-4824页

作者： Qing-Yu Liu dong-Ming Lai Chao Liu Lei zhang wei-dong zhang Hai-Gang Li Ming Gao Department of Radiology Sun Yatsen Memorial Hospital Sun Yat-sen University Guangzhou 510120 Guangdong Province China

AIM:To investigate the clinicopathologic features of bile duct tumor thrombus(BDTT) occurrence after treatment of primary small hepatocellular carcinoma(sHCC) .METHODS:A total of 423 patients with primary sHCC admitted to our hospital underwent surgical resection or local *** follow-up,only six patients were hospitalized due to obstructive jaundice,which occurred 5-76 mo after initial *** clinicopathologic features of these six patients were ***:Six patients underwent hepatic resection(n=5) or radio-frequency ablation(n=1) due to primary *** cases had an R1 resection margin,and one case had an ablative margin less than 5.0 *** vascular infiltration,microsatellites or bile duct/canaliculus affection was noted in the initial resected *** the follow-up,imaging studies revealed a macroscopic BDTT extending to the common bile duct in all six *** patients had a concomitant intrahepatic recurrent *** re-resection of intrahepatic recurrent tumors and removal of BDTTs(n=4) ,BDTT removal through choledochotomy(n= 1) ,and conservative treatment(n=1) was *** portal vein invasion was noted in three of the four resected *** six patients died,with a mean survival of 11 mo after BDTT removal or conservative ***:BDTT occurrence is a rare,special recurrent pattern of primary *** with BDTTs extending to the common bile duct usually have an unfavorable prognosis even following aggressive *** resection or ablative margins against primary sHCC may be a risk factor for BDTT development.

关键词： Small hepatocellular carcinoma Recurrence Bile ducts Jaundice Diagnosis

来源：

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

Establishment and industrial practice of high-temperature process evaluation system in sintering

引用

Journal of Iron and Steel Research International 2018年第9期25卷 910-922页

作者： Yuan-dong Pei Sheng-li Wu Xiao-jing Shao Zhi-xing Zhao Gang An Ze-jun Ma wei-dong zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083 China Shougang Research Institute of Technology Beijing 100043China Beijing Key Laboratory of Green Recyclable Process for Iron and Steel Production Technology Beijing 100043 China Shougang Jingtang Integrated Iron and Steel Co. Ltd.Tangshan 063200 Hebei China

The behaviors of typical iron ores at high temperature were observed by confocal scanning laser microscopy. Four critical temperature points and liquid flow velocity at high temperatures of iron ores were obtained and the temperature points contain temperature at which sample starts to shrink, temperature at which the initial liquid phase forms, temperature at which a lot of liquid forms and temperature at which liquid consolidation ends. Under the same CaO to Fe203 ratio, the liquid phase fluidity of iron ore fines of Carajas （IOC） is good. However, under the same basicity, as the content of SiO2 in IOC is low, the liquid phase fluidity of IOC is much smaller than that of Yandi fine. After analysis of the initial formation and development of the liquid phase and the final consolidation process, the high-temperature process evaluation system （HTPES for short） of iron ore was established. The idea of ＂dense ore matching fusible ore＂ instead of ＂relatively fusible ore＂ was proposed based on the results of HTPES and applied in ore matching of a sinter plant from Shougang Jingtang. The use of IOC （13-18%） instead of standard sintering fines （SSF） improved liquid phase fluidity and ensured the sinter quality. Furthermore, the use of IOC fine （18-23%） with Hainan fine （0-2%） instead of SSF, a mixture of hematite and Marra Mamba ore and concentrates guaranteed the quality of sinter ore through improving fluidity, in the meantime reducing ore matching costs. With the establishment and application of HTPES, the sinter plant has achieved good economic benefits under the premise of ensuring the quality of sinter ore.

关键词： Sinter Iron ore In situ observation Fluidity Evaluation Industrial practice

来源：

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

Hepatic focal nodular hyperplasia in children:Imaging features on multi-slice computed tomography

引用

World Journal of Gastroenterology 2012年第47期18卷 7048-7055页

作者： Qing-Yu Liu wei-dong zhang dong-Ming Lai Ying Ou-yang Ming Gao Xiao-Feng Lin Department of Radiology Sun Yat-sen Memorial HospitalSun Yat-sen University Department of Radiology Cancer CenterSun Yat-sen University Department of General Surgery Sun Yat-sen Memorial HospitalSun Yat-sen University Department of Pediatrics Sun Yat-sen Memorial HospitalSun Yat-sen University

AIM:To retrospectively analyze the imaging features of hepatic focal nodular hyperplasia(FNH) in children on dynamic contrast-enhanced multi-slice computed tomography(MSCT) and computed tomography angiography(CTA) ***:From September 1999 to April 2012,a total of 218 cases of hepatic FNH were confirmed by either surgical resection or biopsy in the Sun Yat-sen Memorial Hospital of Sun Yat-sen University and the Cancer center of Sun Yat-sen University,including 12 cases(5.5%) of FNH in children(age ≤ 18 years old).All the 12 pediatric patients underwent *** retrospectively analyzed the imaging features of FNH lesions,including the number,location,size,margin,density of FNH demonstrated on pre-contrast and contrastenhanced computed tomography(CT) scanning,central scar,fibrous septa,pseudocapsule,the morphology of the feeding arteries and the presence of draining vessels(portal vein or hepatic vein).RESULTS:All the 12 pediatric cases of FNH had solitary *** maximum diameter of the lesions was 4.0-12.9 cm,with an average diameter of 5.5 ± 2.5 *** majority of the FNH lesions(10/12,83.3%) had well-defined *** scar(10/12,83.3%) and fibrous septa(11/12,91.7%) were commonly found in children with *** scar was either isodense(n = 7) or hypodense(n = 3) on pre-contrast CT images and showed progressive enhancement in 8 cases in the equilibrium *** septa were linear hypodense areas in the arterial phase and isodense in the portal and equilibrium *** was very rare(1/12,8.3%) in pediatric *** the exception of central scars and fibrous septa within the lesions,all 12 cases of pediatric FNH were homogenously enhanced on the contrast-enhanced CT images,significantly hyperdense in the arterial phase(12/12,100.0%),and isodense in the portal venous phase(7/12,58.3%) and equilibrium phase(11/12,91.7%).Central feeding arteries inside the tumors were observed on CTA images for all 12 cases of FNH,whereas no neovascu

关键词： Focal nodular hyperplasia Liver Children Benign hepatic lesions X-ray Computed tomography

来源：

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

Effect of sigma phase precipitation on microstructure and properties of cast ZG0Cr26Ni5Mo3Cu3 duplex stainless steel under different heat treatments

引用

China Foundry 2018年第3期15卷 182-188页

作者： Ze-hua Zhu wei-dong zhang Xiao-hui Tu Xiao-jian Wang wei Li Institute of Advanced Wear & Corrosion Resistant and Functional Materials Jinan University National Joint Engineering Research Center of High Performance Metal Wear Resistant Materials Technology Jinan University Zhongshan Guangzhong Foundry & Rolling Co. Ltd.

ZG0Cr26Ni5Mo3Cu3 Duplex Stainless Steel （DSS） was solution treated at 1,060 ℃ for 3 h,followed by water cooling. Tempering treatments were conducted at 720, 750 and 780 ℃, respectively, for 16 h,followed by air cooling. The microstructures of ZG0Cr26Ni5Mo3Cu3 duplex stainless steel samples treated at different tempering temperatures were observed by scanning electron microscope （SEM） and energy dispersal spectroscopy （EDS）, and the phase consitutions were analyzed using X-ray diffraction （XRD）. The effects of the precipitation of sigma （σ） phase on the duplex phase percentage, hardness, impact toughness and corrosion resistance of the DSS were studied. Results showed that microstructures of ZG0Cr26Ni5Mo3Cu3 after solution treatment consists of ferrite （α） phase and austenite （γ） phase; after being tempered at different temperatures,σ phase appeared due to a eutectoid-type reaction of α→σ＋γ2 during tempering treatment. It was observed that σ phase distributed along the grain boundary. The volume fraction of σ and γ phases increased with increasing tempering temperature in the range of 720 to 780 oC, whereas the volume fraction of α phase showed the opposite trend. When the percentage of σ phase increased, the hardness of steel also increased. In the solution treated steel, hardness was measured to be only 244.0 HB, because σ phase did not appear. However, itincreased to 391.8 HB when the DSS was tempered at 780 oC because a great of deal of σ phase appeared. The impact toughness and corrosion resistance of DSS decreased when the percentage of σ phase increased.

关键词： Duplex stainless steel tempering sigma phase hardness impact toughness corrosion resistance

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

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：