检索结果-南通市图书馆

Stability and guaranteed cost control for uncertain time-delay Lur'e systems

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2008年第3期19卷 546-554页

作者： zhang Dongmei yu Li zhang Wen'an Coll. of Science Zhejiang Uinv. of Technology Hangzhou 310032 P. R. China Dept. of Automation Zhejiang Uinv. of Technology Hangzhou 310032 P. R. China

The problem of delay-dependent stability and guaranteed cost control （GCC） for a class of uncertain time-delay Lur＇e systems are studied. By using an improved integral inequality,a less conservative delay-dependent stability criterion is formulated as the feasibility problem of the linear matrix inequality （LMI）. The criterion is proved theoretically to be less conservative than some existing results for linear time-delay systems. Because of the fact that the matrices in the LMI-based stability criteria usually have different dimensions, different structures, and different variables, the conservatism analysis of the criteria is difficult. This study brings about a new insight into the comparison of conservatism among different stability criteria, which are expressed in certain LMI forms. The existence of the guaranteed cost controller is given in terms of matrix inequalities. The condition can be solved by using an iterative procedure and does not need any parameter tuning. A numerical example is given to illustrate the effectiveness of the proposed method.

关键词： guaranteed cost control absolute stability LMI delay-dependent.

Overall water splitting over conjugated polymer photocatalysts with crystal facets modulated

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2020年第11期63卷 1582-1583页

作者： yu Qi Fuxiang zhang State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian National Laboratory for Clean EnergyDalian 116023China

Photocatalytic overall water splitting(OWS)for H2 and O2 evolution with a 2:1 stoichiometric ratio is one of the most promising ways to convert solar energy into chemical one,but it confronts huge challenges in consideration of the uphill water oxidation with four-electron transfer[1].During the past half century,great efforts have been made to the inorganic semiconductors-based photocatalysts,and to date the maximal apparent quantum efficiency(AQE)of OWS under ultra violet(UV)light has reached over 95%,as high as that of natural photosynthesis[2].Comparatively,however,the research on water splitting using conjugated polymers or hybrid metal-organic frameworks(MOFs)for photocatalysts is still in the infancy stage,and the achievement of OWS on them is tremendously limited because of additional challenges in addressing their poor charge separation and photochemical stability[3,4].

关键词： splitting conjugated photochemical

Methods for determining unimpeded aircraft taxiing time and evaluating airport taxiing performance

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第2期30卷 523-537页

作者： yu zhang Qing Wang Civil and Environmental Engineering University of South Florida College of Air Traffic Management Civil Aviation University of China College of Transportation Engineer Tongji University

The objective of this study is to improve the methods of determining unimpeded（nominal） taxiing time,which is the reference time used for estimating taxiing delay,a widely accepted performance indicator of airport surface *** reviewing existing methods used widely by different air navigation service providers（ANSP）,new methods relying on computer software and statistical tools,and econometrics regression models are *** models are highly recommended because they require less detailed data and can serve the needs of general performance analysis of airport surface *** proposed econometrics model outperforms existing ones by introducing more explanatory variables,especially taking aircraft passing and over-passing into the considering of queue length calculation and including runway configuration,ground delay program,and weather *** length of the aircraft queue in the taxiway system and the interaction between queues are major contributors to long taxi-out *** proposed method provides a consistent and more accurate method of calculating taxiing delay and it can be used for ATM-related performance analysis and international comparison.

关键词： Aircraft taxiing Airport performance Econometric regression modeling Queue length Simulation analysis Taxiway system

MULTIGRID ALGORITHM FOR THE COUPLING SYSTEM OF NATURAL BOUNDARY ELEMENT METHOD AND FINITE ELEMENT METHOD FOR UNBOUNDED DOMAIN PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2007年第1期25卷 13-26页

作者： Sheng zhang Dehao yu School of Mathematical Sciences and LPMC Nankai University Tianjin 800071 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

In this paper, some V-cycle multigrid algorithms are presented for the coupling system arising from the discretization of the Dirichlet exterior problem by coupling the natural boundary element method and finite element method. The convergence of these multigrid algorithms is obtained even with only one smoothing on all levels. The rate of convergence is found uniformly bounded independent of the number of levels and the mesh sizes of all levels, which indicates that these multigrid algorithms are optimal. Some numerical results are also reported.

关键词： Multigird algorithm Finite element method Boundary element method Coupling Unbounded domain problem.

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

Split nitrogen fertilizer application improved grain yield in winter wheat (Triticum aestivum L.) via modulating antioxidant capacity and ^(13)C photosynthate mobilization under water-saving irrigation conditions

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2021年第1期10卷 290-302页

作者： Zhen zhang Zhenwen yu Yongli zhang yu Shi Key Laboratory of Crop Ecophysiology and Farming System Ministry of AgricultureShandong Agricultural UniversityTai-an 271017ShandongChina

A water-saving cultivation technique of supplementary irrigation based on soil moisture levels has been adopted for winter wheat production in the Huang-Huai-Hai Plain of China,due to the enhanced water-use ***,appropriate split nitrogen management may further improve crop growth and grain ***,we conducted a 2-year field experiment to determine if split nitrogen management might improve wheat productivity by enhancing ^(13)C photosynthate mobilization and the antioxidant defense system under water-saving *** nitrogen management involved a constant total nitrogen rate(240 kg ha^(−1))split in four different proportions between sowing and jointing stage,i.e.,10:0(N1),7:3(N2),5:5(N3),and 3:7(N4).The N3 treatment significantly enhanced“soil-plant analysis development”values,superoxide dismutase antioxidant activity,soluble protein content,sucrose content,and sucrose phosphate synthetase activity,although it reduced the accumulation of malondialdehyde(MDA).The N3 treatment ultimately increased the amount of dry matter assimilation after anthesis *** addition,the ^(13)C isotope tracer experiment revealed that the N3 treatment promoted the assimilation of carbohydrates after anthesis and their partitioning to the developing *** to the unequal ratio treatments(N1,N2,and N4),the equal ratio treatment(N3)increased grain yield by 5.70–16.72%via increasing 1000-grain weight and number of grains per spike in both growing ***,we recommend the use of a 5:5 basal-topdressing split nitrogen fertilizer application under water-saving irrigation conditions to promote antioxidant enzyme activity and the remobilization of photosynthate after anthesis for improving wheat grain yield.

关键词： Split nitrogen fertilization Modulating antioxidant capacity ^(13)C photosynthate mobilization Water-saving irrigation

Local-Do Fs of Airborne Radar Clutter for Reduced-Dimensional STAP with Sparse Antenna Array

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 2015年第2期24卷 426-433页

作者： zhang Zenghui yu Wenxian School of Electronic Science and Electrical Engineering Shanghai Jiao Tong University

Space-time adaptive processing(STAP)technique can mitigate airborne radar clutter and detect moving targets effectively. Based on adaptive radar theory, the Degrees-of-freedom(Do F) of a STAP processor should be larger than that of the received clutter. The local-Do Fs of clutter for Reduced-dimensional STAP(RDSTAP) methods with sparse linear array are studied. The proposed formulas show that the local-Do Fs of clutter can be estimated as the product of the equivalent clutter bandwidth with the equivalent sampling interval.

关键词： Local-Do Fs of clutter Space-time adaptive processing Reduced-dimension Sparse linear array Clutter mitigation

Single-atom catalysts for neutral zinc-air batteries

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Materials 2024年第5期67卷 1674-1675页

作者： Jiaxu zhang Minghao yu Faculty of Chemistry and Food Chemistry&Center for Advancing Electronics Dresden(CfAED) Technische Universität DresdenDresden01062Germany

The escalating global energy demand underscores the urgency of developing sustainable battery ***-air batteries(ZABs)have emerged as promising candidates due to their costeffectiveness,safety,and high energy density[1-4].Conventional ZABs typically rely on a four-electron(4e-)oxygen reduction reaction(ORR)in strongly alkaline electrolytes.

关键词： battery neutral typically

Differences in hoarding behavior between captive and wild sympatric rodent species

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2011年第6期57卷 725-730页

作者： Hongmao zhang yu WANG Laboratory of Ecology and Evolutionary Biology College of Life Science Central China Normal University Wuhan 430079 China Institute of Zoology the Chinese Academy of Sciences Beijing 100101 China

In hand reared birds and mammals, it is generally considered that the development of hoarding behavior is the result of an interaction between the development and maturation of the nervous system and learning from individual experience. How- ever, few studies have been done on wild animals. We tested differences in hoarding behavior between captive reared and wild individuals of two sympatric small rodents, Korean field mice Apodemus peninsulae and Chinese white-bellied rats Niviventer confucianus. Our aim was to identify if lack of experience from the wild would result in poorly developed hoarding behavior. The Korean field mice perform scatter- and larder-hoarding behaviors whereas Chinese white-bellied rats hoard food in larders only. Within outdoor enclosures we compared seed-hoarding behavior in reared juveniles （RJ, 40-50 d old, pregnant mothers were captured in the wild）, wild juveniles （WJ, as young as the RJ） and wild adults （WA, over-winter animals）. We found that a lack of experience from the wild had significant effects on seed-hoarding behavior for both species. The RJ-group removed and hoarded fewer seeds than the WJ- and WA-groups. The two latter groups hoarded seeds in a similar way. In the Korean filed mouse the ILl-group placed more seeds on the ground surface than other groups. These findings suggest that wild experience is important for the acquisition of an appropriate food-hoarding behavior （especially for scatter-hoarding） in these species

关键词： Behavioral ontogeny Food-hoarding behavior Instinct Learning Practice Social experience