检索结果-南通市图书馆

Weighted average consensus problem in networks of agents with diverse time-delays

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2014年第6期25卷 1056-1064页

作者： wenhui liu Feiqi Deng Jiarong Liang Xuekui Yan College of Automation Science and Engineering South China University of Technology School of Computer and Electronic Information Guangxi University

This paper studies the weighted average consensus problem for networks of agents with fixed directed asymmetric unbalance information exchange topology. We suppose that the classical distributed consensus protocol is destroyed by diverse time-delays which include communication time-delay and self time-delay. Based on the generalized Nyquist stability criterion and the Gerschgorin disk theorem, some sufficient conditions for the consensus of multi-agent systems are obtained. And we give the expression of the weighted average consensus value for our consensus protocol. Finally, numerical examples are presented to illustrate the theoretical results.

关键词： networks of agents distributed control weighted average consensus time-delay digraph theory

Random packing of tetrahedral particles using the polyhedral discrete element method

在线全文

学校读者我要写书评

暂无评论

Particuology 2015年第6期13卷 109-117页

作者： Shiwei Zhao Xiaowen Zhou wenhui liu Chengguang Lai School of Civil Engineering and Transportation South China University of Technology Guangzhou 510640 China State Key Laboratory of Subtropical Building Science Guangzhou 510640 China Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong Higher Education Institutes Cuangzhou 510275 China

The random packing of tetrahedral particles is studied by applying the discrete element method （DEM）, which simulates the effects of friction, height ratio, and eccentricity. The model predictions are ana- lyzed in terms of packing density and coordination number （CN）. It is demonstrated that friction has the maximal effect on packing density and mean CN among the three parameters. The packing den- sity of the regular tetrahedron is 0.71 when extrapolated to a zero friction effect. The shape effects of height ratio and eccentricity show that the regular tetrahedron has the highest packing density in the family of tetrahedra, which is consistent with what has been reported in the literature. Compared with geometry-based packing algorithms, the DEM packing density is much lower. This demonstrates that the inter-particle mechanical forces have a considerable effect on packing. The DEM results agree with the published experimental results, indicating that the polyhedral DEM model is suitable for simulating the random packing of tetrahedral particles.

关键词： Discrete element method Random packing Tetrahedral particle Coordination number Packing density

Observer-Based Event-Triggered Tracking Control of Leader-Follower Systems with Time Delay

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

Journal of Systems Science & Complexity 2016年第4期29卷 865-880页

作者： liu wenhui YANG Chunjie SUN Youxian QIN Jiaxiang College of Control Science and Engineering Zhejiang University

This paper studies the tracking control of general linear multi-agent systems with out time delays. The observer-based event-triggered control schemes will be considered or with- For the conventional distributed tracking protocol, the authors will not update the relative state in continuous time, i.e., the relative state will be updated by some events which happened in discrete time. A completely decentralized event-trigger will be designed for leader-follower systems. It is shown that all followers can track the leader asymptotically by the proposed protocol, if the feedback gain matrices are designed appropriately. Numerical simulations are also provided and the results show highly consistent with the theoretical results.

关键词： Consensus distributed control event-triggered control multi-agent systems time delay tracking control.

The microstructure evolution and deformation mechanism in a casting AM80 magnesium alloy under ultra-high strain rate loading

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第11期10卷 3205-3216页

作者： Pengcheng Guo Xiao liu Biwu Zhu wenhui liu Liqiang Zhang School of Mechanical and Electrical Engineering Central South University of Forestry and TechnologyChangsha 410004China School of Material Science and Engineering Hunan University of Science and TechnologyXiangtanHunan 411201China

Ultra-high strain rate impact tests were conducted by Split-Hopkinson pressure bar to investigate the microstructure evolution and impact deformation mechanism of a solution treated casting AM80 Mg alloy at 25, 150 and 250 ℃ with a strain rate of 5000 s^(-1). The microcrack and dynamic recrystallization(DRX) preferentially nucleate at grain boundary(GB) and twin boundary(TB), especially at the intersections between GBs and TBs, and then propagate along twin direction. In contrast, the adiabatic shear bands preferentially occur at high-density twined regions. At 25 ℃, the dominated deformation mechanisms are basal slip and twinning. As deformation temperature increases to 150and 250℃, the deformation gradually shifts to be dominated by a coordinated mechanism among non-basal slip, twinning and DRX. The flow stress behavior and deformation mechanism indicate that the degree of decrease in flow stress with temperature is associated with the change of deformation mode.

关键词： AM80 mg alloy Deformation mechanism Ultra-high strain rate Twinning Dynamic recrystallization

The Enormous Potential of Gas Generation from Carboxylic Acid Salts

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2021年第4期95卷 1429-1430页

作者： WANG Qingtao liu wenhui LI Yining liu Jinzhong State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi'an 710069China State Key Laboratory of Organic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

Objective Up to 45% of total organic carbon(TOC) was probably lost during acid treatment in carbonate-rich rocks(Froelich, 1980). Some scientists thought these acidsoluble organic matters were largely contributed from carboxylic acid salts, which were commonly developed in alkaline carbonate formations and could potentially be excellent sources for natural gas stored in Early Paleozoic carbonate rocks in the Ordos Basin(Chong and McKay, 1984;liu et al., 2017).

关键词： alkaline salts carbonate

The Openness Degree Study of the Jiaoshiba Shale Gas, Sichuan Basin, China–Potential Factor Responsible for Reversed Isotope Series

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2018年第6期92卷 2457-2459页

作者： ZHAO Heng liu wenhui WANG Xiaofeng Key Laboratory of Mineral Resources in Coal Measures China National Administration of Coal GeologyKey Laboratory of Shale GasChina National Administration of Coal GeologyJiangsu Geology and Mineral Resources Design and Research InstituteXuzhou 221006JiangsuChina Gansu Provincial Key Laboratory of Petroleum Resources Key Laboratory of Petroleum Resources ResearchLanzhou Center for Oil and Gas ResourcesInstitute of Geology and GeophysicsChinese Academy of SciencesLanzhou 730000China Wuxi Research Institute of Petroleum Geology Sinopec Petroleum Exploration & Production Research InstituteWuxi 214151JiangsuChina University of Chinese Academy of Sciences Beijing 100049China Northwest University Xian 710069China

Objective Reversed alkane δ;C and δ;H values in many prolific shale plays all over the world have aroused much attention in the study of the formation mechanism of reversed isotope series in alkanes in the past few years（Zou Caineng et al., 2016）. Although many researchers have put forward different hypotheses, the mechanism has not been well understood yet. The openness degree of oil and gas system

关键词： Potential Factor Responsible for Reversed Isotope Series The Openness Degree Study of the Jiaoshiba Shale Gas China

Inhibitory Effect of Vibrio neocaledinocus sp. and Pseudoalteromonas piscicida Dual-Species Biofilms on the Corrosion of Carbon Steel

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2022年第4期35卷 551-562页

作者： Masoumeh Moradi Jianlin Li wenhui liu Dake Xu Fuhui Wang Shenyang National Laboratory for Materials Science Northeastern UniversityShenyang 110819China Key Laboratory for Anisotrotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China

Multi-species biofilms are found in various bacterial habitats and have industrial relevance. These complex bacterial communities have synergetic effects, unlike a single species. Therefore, it is critical to evaluate these complex communities as a whole. Here, the inhibitory eff ect of single-and dual-species biofilms of Vibrio neocaledinocus sp. and Pseudoalteromonas piscicida for A36 carbon steel corrosion was investigated. The results demonstrated that the synergistic interactions of the monoculture increased the overall biomass production of the dual-species biofilm, but the growth rate was reduced in the presence of the dual-species culture due to a lack of nutrients. Field emission scanning electron microscopy images also confirmed the development of biofilms—they became more homogenized via exposure time in both the mono-and dual-species cultures. The corrosion resistance of A36 carbon steel positively increased because of the dual-species interactions. This reached the highest value after four weeks of exposure. The highest corrosion inhibition e fficiency of 99.8% was achieved in the dual-species cultures. Microbial community analysis revealed the high relative abundance of Pseudoalteromonas piscicida during the initial days of exposure, demonstrating the dominant role of this bacterium in the biofilm structure.

关键词： Dual-species biofilm Steel alloys Corrosion inhibitory Electrochemical analysis Cooperative interaction

Accumulation mechanism of mantle-derived helium resources in petroliferous basins, eastern China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第12期65卷 2322-2334页

作者： Xiaofeng WANG Quanyou liu wenhui liu Dongdong ZHANG Xiaofu LI Dong ZHAO State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Beijing 100083China Institute of Energy Peking UniversityBeijing 100871China Petroleum Exploration and Production Research Institute SINOPECBeijing 100083China

A series of marginal-sea basins and fault-depression basins were formed in eastern China under the background of subduction of the West Pacific *** types of helium-rich natural gas reservoirs(He>1000 ppm,1 ppm=1μmol mol^(-1))have been found in these basins:helium-rich CO_(2)gas reservoirs,helium-rich N_(2)gas reservoirs,and helium-rich hydrocarbon gas *** on the analysis of gas geochemical data,the source and accumulation mechanism of helium in these heliumrich natural gas reservoirs were ***-rich natural gas has relatively high 3He/4He ratios(0.88-4.91 Ra,average 2.82 Ra).The ^(3)He/^(4)He ratio characteristics of mantle xenoliths and mantle-derived CO_(2)gas reservoirs indicate that the helium in these helium-rich natural gas reservoirs is mainly mantle-derived(>70%).The original mantle volatile is mainly CO_(2)with a low helium concentration(Helium in the gas reservoir is mainly related to the dissolution and mineralization of CO_(2).During this process,the CO_(2)/3He ratio decreases from 2×10^(9)to approximately 2×10^(6).As CO_(2)dissolves and mineralizes,the concentration of conservative gases(He and N_(2))increases in the remaining CO_(2)gas proportionally to the loss of CO_(2).Large amounts of carbonate minerals,such as dawsonite,which are relatively enriched in 13C,are found in CO_(2)reservoirs in eastern *** relative enrichment of^(12)C in residual CO_(2)gas is important evidence of the dissolution and mineralization of CO_(2).The relative abundance of mantle-derived helium and N_(2)gas increases thousands of times during the dissolution and mineralization of CO_(2),which is the main accumulation mechanism of mantle-derived helium-rich CO_(2)gas reservoirs and helium-rich N_(2)gas ***-rich gas from the mantle is mixed with alkane gas generated by organic matter in the sedimentary basin to form helium-rich hydrocarbon gas reservoirs.

关键词： Mantle-derived helium ^(3)He/4He ratio,Helium resources,Helium-rich natural gas,Accumulation mechanism

同方期刊数据库

Unveiling the mechanical response and accommodation mechanism of pre-rolled AZ31 magnesium alloy under high-speed impact loading

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第4期10卷 1096-1108页

作者： Xiao liu Hui Yang Biwu Zhu Yuanzhi Wu wenhui liu Changping Tang Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province Hunan University of Science and TechnologyXiangtanHunan 411201China Research Institute of Automobile Parts Technology Hunan Institute of TechnologyHengyangHunan 421002China

Split Hopkinson pressure bar(SHPB)tests were conducted on pre-rolled AZ31 magnesium alloy at 150–350℃ with strain rates of 2150s-1,3430s^(-1) and *** mechanical response,microstructural evolution and accommodation mechanism of the pre-rolled AZ31 magnesium alloy under high-speed impact loading were *** twin and shear band are prevailing at low temperature,and the coexistence of twins and recrystallized grains is the dominant microstructure at medium temperature,while at high temperature,dynamic recrystallization(DRX)is almost *** increment of temperature reduces the critical condition difference between twinning and DRX,and the recrystallized temperature decreases with increasing strain *** mechanical response is related to the competition among the shear band strengthen,the twin strengthen and the fine grain strengthen and determined by the prevailing grain *** fine grain strengthen could compensate soften caused by the temperature increase and the reduction of twin and shear *** high-speed deformation,different twin variants,introduced by pre-rolling,induce different deformation mechanism to accommodate plastic deformation and are in favor for non-basal *** low temperature,the high-speed deformation is achieved by twinning,dislocation slip and the following deformation shear band at different deformation *** high temperature,the high-speed deformation is realized by twinning and dislocation slip of early deformation stage,transition shear band of medium deformation stage and DRX of final deformation stage.

关键词： Mechanical response Pre-twinning Accommodation mechanism Pre-rolled AZ31 magnesium alloy High-speed impact loading