检索结果-南通市图书馆

Interior-stress fields produced by a general axisymmetric punch

在线全文

学校读者我要写书评

暂无评论

Friction 2022年第4期10卷 530-544页

作者： Longxiang YANG Zhanjiang WANG Weiji LIU guocheng zhang Bei PENG School of Automotive Engineering Geely University of ChinaChengdu 641423China Department of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China School of Mechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Center for Robotics University of Electronic Science and Technology of ChinaChengdu 611731China

This work is a supplement to the work of Sneddon on axisymmetric Boussinesq problem in 1965 in which the distributions of interior-stress fields are derived here for a punch with general profile.A novel set of mathematical procedures is introduced to process the basic elastic solutions(obtained by the method of Hankel transform,which was pioneered by Sneddon)and the solution of the dual integral *** processes then enable us to not only derive the general relationship of indentation depth D and total load P that acts on the punch but also explicitly obtain the general analytical expressions of the stress fields beneath the surface of an isotropic elastic *** usually known cases of punch profiles are reconsidered according to the general formulas derived in this study,and the deduced results are verified by comparing them with the classical ***,these general formulas are also applied to evaluate the von Mises stresses for several new punch profiles.

关键词： axisymmetric Boussinesq problem interior stress Hankel transform dual integral equations

Multi-Scale Fusion Algorithm for AUVs Integrated Navigation Systems

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 Beijing Institute of Technology 2019年第4期28卷 725-730页

作者： Yushan Sun Fanyu Wu Yuqi Wang guocheng zhang Bin Kong Science and Technology on Underwater Vehicle Laboratory Harbin Engineering UniversityHarbin 150001China Key Laboratory of System Control and Information Processing Shanghai Jiao Tong UniversityShanghai 200030China Wuhan Second Ship Design and Research Institute Wuhan 430205China

To deal with the low location accuracy issue of existing underwater navigation technologies in autonomous underwater vehicles(AUVs),a distributed fusion algorithm which combines the model's analysis method with a multi-scale transformation method is proposed for integrated navigation system based on ***,integrated navigation system theory and system error sources are introduced in ***,a navigation system's observation equation on the original scale is decomposed into different scales by the discrete wavelet transform method,and noise reduction is performed by setting the wavelet de-noising *** last,the dynamic equation and observation equations are fused on different scales by the wavelet transformation and Kalman *** results show that the proposed algorithm has smaller navigation error and higher navigation accuracy.

关键词： autonomous underwater vehicles(AUVs) integrated navigation system wavelet transform multi-scale transform Kalman filter

Microbial and molecular fossils from the Permian Zoophycos in South China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2007年第8期50卷 1121-1127页

作者： GONG YiMing XU Ran XIE ShuCheng HUANG XianYu HU Bin QI YongAn zhang guocheng Key Laboratory of Biogeology and Environmental Geology of Ministry of Education State Key Laboratory of Geological Processes and Mineral ResourcesChina University of GeosciencesWuhan 430074China Institute of Resources and Environment Key Laboratory of Biogenic Traces&Sedimentary Minerals of Henan ProvinceHenan Polytechnic UniversityJiaozuo 454003China

The trace fossil Zoophycos was enriched in the lower part of the Guadalupian Maokou Formation of Permian in Laibin, Guangxi of South China, and characterized by observable lamellae within its spreiten. Associated with these lamellae are the prolific coccus- and spirillum-shaped microbe fossils. These microbes morphologically identified are 0.4―3.0 μm in diameter or length. Molecular fossils, including normal alkanes (dominated by C18, without an odd-over-even predominance), acyclic isoprenoids (such as pristane (Pr) and phytane (Ph)), extended tricyclic terpanes, pentacyclic triterpanes, steranes, al-kylcyclohexanes, dibenzothiophenes, benzonaphthothiophenes, benzobisbenzothiophenes, were in-strumentally identified in the wackestone characterized by the occurrence of abundant Zoophycos (composite ichnofabric indices are 4) and crowded microbial fossils. The value of the Pr/Ph ratio is less than 1, indicative of a dysoxic condition. The identification of abundant sulfur compounds (the thio-phene series) related to the contribution of reductive sulfur favors the occurrence of sulphate-reducing bacteria. The association of abundant microbial colonies with microbial molecular fossils within the spreiten suggests that trace fossils Zoophycos would be a multifunctional garden carefully constructed by the Zoophycos-producer, where different microbial colonies were orderly and carefully planted and cultured in different minor lamellae within spreiten. Hence, it is proposed that the Zoophycos-producer symbiosed with microbial colonies on the mutual basis of food supply and the redox conditions.

关键词： trace fossils Zoophycos microbes molecular fossils Permian South China

Anomalous Magnetic Behavior in Phase-separated La0.5 Sr0.5 MnO3 +δ Films

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2004年第Z1期22卷 63-65页

作者： Yu Dunbo Ying Qiming zhang guocheng Li Tong Du Yongsheng Wang Bo Yan Hui Grirem Advanced Materials Co. Ltd. Beijing 100088 China Grirem Advanced Materials Co. Ltd.Beijing 100088 China Grirem Advanced Materials Co. Ltd.Beijing 100088 China Thin Film Materials Laboratory Beijing University of Technology Beijing 100022 China Thin Film Materials Laboratory Beijing University of Technology Beijing 100022 China Thin Film Materials Laboratory Beijing University of Technology Beijing 100022 China Thin Film Materials Laboratory Beijing University of Technology Beijing 100022 China

(001)La0.5 Sr0.5MnO3 +δ films on (001)LaA1O3 substrates were prepared by using a RF magnetron sputtering with powder *** low temperature, the films exhibit two phase coexistence, which means that ferromagnetic (FM) clusters are embedded in antiferromagnetic (AFM) ***, a shift in hysteresis loop is unexpectedly observed in this inhomogeneous *** suggest that the anomalous hysteresis loop may result from the unidirectional exchange anisotropy at the interface between AFM and FM clusters.

关键词： phase separation manganite hysteresis loop

Functional traits of tree species with phylogenetic signal co-vary with environmental niches in two large forest dynamics plots

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 Plant Ecology 2014年第2期7卷 115-125页

作者： Jie Yang Xiuqin Ci Mengmeng Lu guocheng zhang Min Cao Jie Li Luxiang Lin Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesNo.88 Xuefu RoadKunmingYunnan 650223China University of Chinese Academy of Sciences No.19A Yuquan RoadBeijing 100049China

Aims While using phylogenetic and functional approaches to test the mechanisms of community assembly,functional traits often act as the proxy of ***,there is little detailed knowledge regarding the correlation between functional traits of tree species and their niches in local *** suggest that the co-varying correlation between functional traits and niches should be the premise for using phylogenetic and functional approaches to test mechanisms of community *** functional traits,phylogenetic and environmental data,this study aims to answer the questions:(i)within local communities,do functional traits of co-occurring species covary with their environmental niches at the species level?and(ii)what is the key ecological process underlying community assembly in Xishuangbanna and Ailaoshan forest dynamic plots(FDPs)?Methods We measured seven functional traits of 229 and 36 common species in Xishuangbanna and Ailaoshan FDPs in tropical and subtropical China,*** also quantified the environmental niches for these species based on conditional *** then analyzed the correlations between functional traits and environmental niches using phylogenetic independent *** examining phylogenetic signals of functional traits using Pagel’sλ,we quantified the phylogenetic and functional dispersion along environmental gradients within local tree *** Findings For target species,functional traits do co-vary with environmental niches at the species level in both of the FDPs,supporting that functional traits can be used as a proxy for local-scale environmental *** traits show significant phylogenetic signals in both of the *** found that the phylogenetic and functional dispersion were significantly clustered along topographical gradients in the Ailaoshan FDP but overdispersion in the Xishuangbanna *** patterns of phylogenetic and functional dispersion suggest that environmental filterin

关键词： forest dynamics plot local scale phylogenetic independent contrast phylogenetic signal phylogenetic dispersion functional dispersion

Contrasting effects of space and environment on functional and phylogenetic dissimilarity in a tropical forest

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 Plant Ecology 2019年第2期12卷 314-326页

作者： Mengesha Asefa Calum Brown Min Cao guocheng zhang Xiuqin Ci Liqing Sha Jie Li Luxiang Lin Jie Yang Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of Sciences666303 YunnanChina Karlsruhe Institute of Technology Institute of Meteorology and Climate ResearchAtmospheric Environmental Research(IMK-IFU)Kreuzeckbahnstraße 1982467 Garmisch-PartenkirchenGermany

Aims The evolutionary history and functional traits of species can illumi-nate ecological processes supporting coexistence in diverse forest ***,little has been done in decoupling the rela-tive importance of these mechanisms on the turnover of phylogenetic and functional characteristics across life stages and spatial ***,this study aims to estimate the contribution of environment and dispersal on the turnover of phylogenetic and functional diversity across life stages and spatial scales,in order to build a coherent pic-ture of the processes responsible for species *** We conducted the study in Xishuangbanna Forest Dynamics Plot in Yunnan Province,southwest *** used four different spatial point process models to estimate the relative importance of disper-sal limitation and environmental *** functional traits and phylogenetic relationships of all individual trees were incorporated in the analyses to generate measures of dissimilarity in terms of pair-wise and nearest-neighbor phylogenetic and functional characteris-tics across life stages and spatial *** Findings We found non-random patterns of phylogenetic and functional turnover across life stages and spatial *** filtering structured pairwise phylogenetic and functional beta diversity across spatial scales,while dispersal limitation alone,and in combination with environment filtering,shaped nearest neighbor phylogenetic and functional beta *** relative importance of dispersal limitation and environmental filtering appeared to change with life stage but not with spatial *** findings suggest that phylogenetic and functional beta diversity help to reveal the ecological processes responsible for evolu-tionary and functional assembly and highlight the importance of using a range of different metrics to gain full insights into these processes.

关键词： community assembly functional beta diversity life stage phylogenetic beta diversity spatial point pattern

Dynamics Modeling and Simulation of Autonomous Underwater Vehicles with Appendages

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 Marine Science and Application 2013年第1期12卷 45-51页

作者： Yumin Su Jinxin Zhao Jian Cao guocheng zhang State Key Laboratory of Autonomous Underwater Vehicle Harbin Engineering University Harbin 150001 China

To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle＇s （AUV） motion controller, a six-degree of freedom （6-DOF） dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV＇s motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.

关键词： autonomous underwater vehicle (AUV) motion performance dynamics modeling appendages simulation system

Model Predictive Controller Design for the Dynamic Positioning System of a Semi-submersible Platform

在线全文

学校读者我要写书评

暂无评论

Journal of Marine Science and Application 2012年第3期11卷 361-367页

作者： Hongli Chen Lei Wan Fang Wang guocheng zhang Key Laboratory of Science and Technology for National Defense Harbin Engineering University Harbin 150001 China

This paper researches how to apply the advanced control technology of model predictive control （MPC） to the design of the dynamic positioning system （DPS） of a semi-submersible platform. First, a linear low-frequency motion model with three degrees of freedom was established in the context of a semi-submersible platform. Second, a model predictive controller was designed based on a model which took the constraints of the system into account. Third, simulation was carried out to demonstrate the feasibility of the controller. The results show that the model predictive controller has good performance and good at dealing with the constraints or the system.

关键词： dynamic positioning system model predictive controller constraints handling semi-submersibleplatform low-frequency motion model

Predictive S Control of AUV Based on Model of Support Vector Machine

在线全文

学校读者我要写书评

暂无评论

Predictive S Control of AUV Based on Model of Support Vector...