检索结果-南通市图书馆

Higher-order Optimality Conditions and Duality for Approximate Solutions in Non-convex Set-valued Optimization

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2019年第3期35卷 620-628页

作者： Guo-lin YU tian-tian GONG North Minzu University

This paper deals with higher-order optimality conditions and duality theory for approximate solutions in vector optimization involving non-convex set-valued ***,under the assumption of near cone-subconvexlikeness for set-valued maps,the higher necessary and sufficient optimality conditions in terms of Studniarski derivatives are derived for local weak approximate minimizers of a set-valued optimization ***,applications to Mond-Weir type dual problem are presented.

关键词： studniarski derivatives optimality conditions set-valued optimization problem efficiency duality

Accelerated life-time test of MEA durability under vehicle operating conditions in PEM fuel cell

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2017年第3期11卷 326-333页

作者： tian tian Jianjun TANG Wei GUO Mu PAN State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Hubei Provincical Key Laboratory of Fuel Cell Wuhan University of Technology Wuhan 430070 China

In this paper, a novel accelerated test method was proposed to analyze the durability of MEA, considering the actual operation of the fuel cell vehicle. The proposed method includes 7 working conditions： open circuit voltage （OCV）, idling, rated output, overload, idling-rated cycle, idling-overload cycle, and OCV-idling cycle. The experimental results indicate that the proposed method can effectively destroy the MEA in a short time （165 h）. Moreover, the degradation mechanism of MEA was analyzed by measuring the polarization curve, CV, SEM and TEM. This paper may provide a new research direction for improving the durability of fuel cell.

关键词： polymer electrolyte membrane fuel cell accelerated life-time test load cycling test durability

A Coding Scheme for Noisy Image Based on Layer Segmentation

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

Chinese Journal of Electronics 2016年第4期25卷 700-705页

作者： LI Tao tian Xin XIONG Chengyi tian Jinwen Nanjing Research Institute of Electronics Technology Wuhan University South–Central University for Nationalities Huazhong University of Science and Technology

Heavy noises distribute in the images when imaging in a poor *** randomness of noises makes pixels distributing singularly,which weakens the1-D piecewise smooth property of original ***,wavelets-based compression method no longer works *** this paper,a layer segmentation based compression scheme is proposed for gray *** textures and some high frequency noises are described in a high frequency layer while the coarse part of the image is described in the low frequency *** high frequency layer is represented by a joint dictionary,and the low frequency layer is coded with the traditional *** proposed scheme is tested on nature images and synthetic *** results show that the proposed scheme achieves better rate-distortion performance compared with several competing compression ***,further degradation of edges is avoided by the proposed compression scheme.

关键词： Image coding Noisy image model Sparse representation Edge detection

Improving differential evolution with a new selection method of parents for mutation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2016年第2期10卷 246-269页

作者： Yiqiao CAI Yonghong CHEN tian WANG Hui tian College of Computer Science and Technology Huaqiao University Xiamen 361021 China

In differential evolution （DE）, the salient feature lies in its mutation mechanism that distinguishes it from other evolutionary algorithms. Generally, for most of the DE algorithms, the parents for mutation are randomly chosen from the current population. Hence, all vectors of population have the equal chance to be selected as parents without selective pressure at all. In this way, the information of population cannot be fully exploited to guide the search. To alleviate this drawback and improve the performance of DE, we present a new selection method of parents that attempts to choose individuals for mutation by utilizing the population information effectively. The proposed method is referred as fitnessand-position based selection （FPS）, which combines the fitness and position information of population simultaneously for selecting parents in mutation of DE. In order to evaluate the effectiveness of FPS, FPS is applied to the original DE algorithms, as well as several DE variants, for numerical optimization. Experimental results on a suite of benchmark functions indicate that FPS is able to enhance the performance of most DE algorithms studied. Compared with other selection methods, FPS is also shown to be more effective to utilize information of population for guiding the search of DE.

关键词： differential evolution mutation operator parents selection population information numerical optimization

在线全文

学校读者我要写书评

暂无评论

高速飞行器气动光学效应

中山大学学报（自然科学版）（中英文） 2025年第1期64卷 257-264页

作者：田立丰杨东霖黄开诱中山大学航空航天学院广东深圳518107 深圳市智能微小卫星星座技术与应用重点实验室广东深圳518107

采用数值模拟、计算光学方法和理论,对超声速飞行器流场进行数值模拟研究,获取不同飞行高度和攻角下光学窗口上方流场的密度分布,根据Gladstone-Dale关系得到光学窗口上方的折射率场,利用光线追迹法计算流场光程差分布情况。对流场光程... 详细信息

采用数值模拟、计算光学方法和理论,对超声速飞行器流场进行数值模拟研究,获取不同飞行高度和攻角下光学窗口上方流场的密度分布,根据Gladstone-Dale关系得到光学窗口上方的折射率场,利用光线追迹法计算流场光程差分布情况。对流场光程差的分布情况进行分析,可以得出结论:随着飞行高度的增加,气动光学效应逐渐减弱;随着攻角的增大,气动光学效应逐渐增强。

关键词：气动光学飞行高度攻角光程差

A novel subsidence monitoring technique based on space-surface bistatic differential interferometry using GNSS as transmitters

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第6期58卷 68-83页

作者： ZENG Tao ZHANG tian tian WeiMing HU Cheng Beijing Key Laboratory of Embedded Real-time Information Processing Technology Radar Research Laboratory School of Information and ElectronicsBeijing Institute of Technology

Synthetic Aperture Radar Differential Interferometry(DIn SAR) technique is an effective tool with large coverage and high spatial accuracy for subsidence monitoring. Nevertheless, the temporal resolution is usually poor so that rapid deformation cannot be measured due to the long revisit time of radar *** SAR Differential Interferometry technique using Global Navigation Satellite System(GNSS) as illuminator has a shorter revisit time, whereas the measurement accuracy is constrained by low signal power, narrow bandwidth and atmospheric delay error. To cope with these problems, in this paper, we propose a novel subsidence monitoring technique based on Space-Surface bistatic Differential Interferometry(SS-DI) with GNSS transmitters, where two stations consist of a reference one and a measurement one that are deployed on the ground. First, we applied a space differential processing between two stations to cancel identical errors such as tropospheric and ionospheric errors etc. Then we used a long time coherent integration to improve the signal noise ratio. Subsequently, we also utilized a time differential processing to construct double differential equations with respect to unknown deformation variables. Finally, we solved the equations to obtain a highly accurate estimation of three dimension deformation. Furthermore, an SS-DI experiment using Beidou-2 as transmitters was carried out to validate the proposed method, where a high accuracy(0.01 mm) device was utilized to simulate subsidence deformation. The experimental results reveal that the proposed method has better performance of spatial measurement accuracy of 0.53 mm compared with differential GPS method.

关键词： differential interferometry subsidence monitoring Beidou-2/Compass-2 space-surface bistatic radar differential GPS

Multivariable Intelligent Decoupling Control System and its Application

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

自动化学报 2005年第1期31卷 123-131页

作者： tian-YouCHAI HengYUE NationalEngineeringandTechnologyResearchCenterforMetallurgicIndustryAutomation NortheasternUniversityShenyang110004P.R.China

Many industrial processes have compositive complexities including multivariable, strong coupling, nonlinearity, time-variant and operating condition variations. Combining multivariable adaptive decoupling control with neural networks, this paper presents a multivariable neural networkbased decoupling control algorithm. This control algorithm is integrated with distributed control technique and intelligent control technique, and a three-leveled intelligent decoupling control system consisting of basic control level, coordinating control level, and management and decision level is developed. The configuration and function of the control system are discussed in detail. This system has been successfully applied in ball mill pulverizing systems of 200MW power units, and remarkable benefits have been obtained.

关键词：神经网络去耦合控制智能去耦合控制系统煤粉碎系统多变量系统应用

Development of a compact DOI-TOF detector module for high-performance PET systems

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第4期28卷 1-7页

作者： Qing-Yang Wei tian-Peng Xu tian-tian Dai Shi Wang Ya-Qiang Liu Yu Gu tian-Yu Ma School of Automatic and Electrical Engineering University of Science and Technology Beijing Beijing 100083 China Department of Engineering Physics Tsinghua UniversityBeijing 100084 China Key Laboratory of Particle and Radiation Imaging (Tsinghua University) Ministry of Education Beijing 100084 China Department of Radiation Oncology China-Japan Friendship Hospital Beijing 100029 China

To increase spatial resolution and signal-to-noise ratio in PET imaging,we present in this paper the design and performance evaluation of a PET detector module combining both depth-of-interaction(DOI) and time-offlight(TOF) *** detector module consists of a staggered dual-layer LYSO block with2 mm × 2 mm × 7 mm ***-compatible SiPM sensors(MicroFJ-30035-TSV,SensL) are assembled into an 8× 8 *** signals from both fast and slow outputs are read out by a 128-channel ASIC *** test its performance,a flood histogram is acquired with a ^(22)Na point source on top of the detector,and the energy resolution and the coincidence resolving time(CRT) value for each individual crystal are *** flood histogram shows excellent crystal separation in both *** average energy resolution at 511 keV is 14.0 and 12.7%at the bottom and top layers,*** average CRT of a single crystal is 635 and 565 ps at the bottom and top layers,*** conclusion,the compact DOI-TOF PET detector module is of excellent crystal identification capability,good energy resolution and reasonable time resolution and has promising application prospective in clinical TOF PET,PET/MRI,and brain PET systems.

关键词： Positron emission tomography SiPM Depth of interaction (DOI) Time-of-flight (TOF)

Design of process and control scheme for cyclohexanol production from cyclohexene using reactive distillation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2021年第12期34卷 96-105页

作者： Mingyuan Hu Hui tian College of Chemistry and Chemical Engineering Yantai UniversityYantai 264005China Collaborative Innovation Center of Comprehensive Utilization of Light Hydrocarbon Resource Yantai UniversityYantai 264005China

Cyclohexanol is a commonly used organic ***,the most promising industrial process for synthesizing cyclohexanol,by cyclohexene hydration,suffers from a low conversion rate and difficult *** this paper,a three-column process for catalytic distillation applicable in the hydration of cyclohexene to cyclohexanol was established to solve *** with Aspen Plus shows that the process has good advantages,the conversion of cyclohexene reached 99.3%,and the product purity was>99.2%.The stable operation of the distillation system requires a good control *** design of the control scheme is very ***,at present,the reactive distillation process for cyclohexene hydration is under investigation experimentally and by steady-state ***,three different plant-wide control schemes were established(CS1,CS2,CS3) and the position of temperature sensitive stage was selected by using sensitivity analysis method and singular value decomposition *** Tyreus-Luyben empirical tuning method was used to tune the controller ***,Aspen Dynamics simulation software was used to evaluate the performance of the three control *** introducing ΔF±20% and χ_(ENE)±5%,comparison the changes in product purity and yield of the three different control *** comparison,we can see that the control scheme CS3 has the best performance.

关键词： Cyclohexene hydration Catalytic distillation Control schemes Dynamic Simulation