Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In t...Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In this paper,nonlinear finite element method is used to investigate the interaction between a polar ship and an ice ridge.The ice ridge is modelled as elastic-plastic material based on Drucker-Prager yield function,with the consideration of the influence of cohesion,friction angle and material hardening.The material model is developed in LS-DYNA and solved using semi-implicit mapping algorithm.The stress distribution of ice ridge and ship,and the ice load history are evaluated through the simulation of multiple collisions.In addition,parametric analysis is performed to investigate the influence of ridge thickness and impact velocity on the ice load and energy absorption.展开更多
延迟容忍移动传感器网络(DTMSN)是一种广泛应用的数据采集网络.提出一种基于社会网络的数据传输策略SNBD(social network-based data delivery scheme)应用于DTMSN.SNBD引入社会网络中的相互作用强度和相称机制,通过计算两传感器节点之...延迟容忍移动传感器网络(DTMSN)是一种广泛应用的数据采集网络.提出一种基于社会网络的数据传输策略SNBD(social network-based data delivery scheme)应用于DTMSN.SNBD引入社会网络中的相互作用强度和相称机制,通过计算两传感器节点之间的相互作用强度值和相称值,作为消息传输时选择下一跳的依据.为了优化节点队列,SNBD采用消息的重要因子和TTL决定队列中消息传递的优先顺序和丢弃原则.模拟实验表明,与现有的几种数据传输策略相比,SNBD不但具有较高的数据传输成功率,而且具有较低的数据传输能耗和传输延迟,并且通过分析发现SNBD的网络寿命是SRAD和FAD的8倍.展开更多
The compaction and stress generation on terrain were always investigated based on empirical approaches or testing methods for tire/soil interaction.However,the analysis should be performed for various tires and at dif...The compaction and stress generation on terrain were always investigated based on empirical approaches or testing methods for tire/soil interaction.However,the analysis should be performed for various tires and at different soil strengths.With the increasing capacity of numerical computers and simulation software,finite element modeling of tire/terrain interaction seems a good approach for predicting the effect of change on the parameters.In this work,an elaborated 3D model fully complianning with the geometry of radial tire 115/60R13 was established,using commercial code Solidwork Simulation.The hyper-elastic and incompressible rubber as tire main material was analyzed by Moony-Rivlin model.The Drucker-Prager yield criterion was used to model the soil compaction.Results show that the model realistically predicts the laboratory tests outputs of the modeled tire on the soft soil.展开更多
Abstract： With the substitution of part Mg in LaMg3 by Cu, the elastic constants CH and C12 increase while C44 decreases, implying an enhanced Poisson effect and smaller resistance to 〈001〉（100） shear. Furthermor...Abstract： With the substitution of part Mg in LaMg3 by Cu, the elastic constants CH and C12 increase while C44 decreases, implying an enhanced Poisson effect and smaller resistance to 〈001〉（100） shear. Furthermore, the bulk modulus B increases, while the shear modulus G, elastic modulus E and anisotropie ratio A are reduced. The calculated Debye temperature of LaCuMg2 is lower, implying the weaker interaction between atoms in LaCuMg2. Then, the stress-strain curves in entire range and the ideal strength at critical strain are studied. The present results show that the lowest ideal tensile strength for LaMg3 and LaCuMg2 is in the 〈100〉 direction. The ideal shear strength on the 〈 1 ^-1 0〉（110） slip system of LaMg3 is greater than LaCuMg2. The density of states and charge density distribution are further studied to understand the inherent mechanism of the mechanical properties.展开更多
文摘Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In this paper,nonlinear finite element method is used to investigate the interaction between a polar ship and an ice ridge.The ice ridge is modelled as elastic-plastic material based on Drucker-Prager yield function,with the consideration of the influence of cohesion,friction angle and material hardening.The material model is developed in LS-DYNA and solved using semi-implicit mapping algorithm.The stress distribution of ice ridge and ship,and the ice load history are evaluated through the simulation of multiple collisions.In addition,parametric analysis is performed to investigate the influence of ridge thickness and impact velocity on the ice load and energy absorption.
文摘延迟容忍移动传感器网络(DTMSN)是一种广泛应用的数据采集网络.提出一种基于社会网络的数据传输策略SNBD(social network-based data delivery scheme)应用于DTMSN.SNBD引入社会网络中的相互作用强度和相称机制,通过计算两传感器节点之间的相互作用强度值和相称值,作为消息传输时选择下一跳的依据.为了优化节点队列,SNBD采用消息的重要因子和TTL决定队列中消息传递的优先顺序和丢弃原则.模拟实验表明,与现有的几种数据传输策略相比,SNBD不但具有较高的数据传输成功率,而且具有较低的数据传输能耗和传输延迟,并且通过分析发现SNBD的网络寿命是SRAD和FAD的8倍.
文摘The compaction and stress generation on terrain were always investigated based on empirical approaches or testing methods for tire/soil interaction.However,the analysis should be performed for various tires and at different soil strengths.With the increasing capacity of numerical computers and simulation software,finite element modeling of tire/terrain interaction seems a good approach for predicting the effect of change on the parameters.In this work,an elaborated 3D model fully complianning with the geometry of radial tire 115/60R13 was established,using commercial code Solidwork Simulation.The hyper-elastic and incompressible rubber as tire main material was analyzed by Moony-Rivlin model.The Drucker-Prager yield criterion was used to model the soil compaction.Results show that the model realistically predicts the laboratory tests outputs of the modeled tire on the soft soil.
基金Project(51071053)supported by the National Natural Science Foundation of ChinaProject(X071117)supported by the Scientific Research Foundation of Guangxi University,ChinaProject(KF0803)supported by the Open Project of Key Laboratory of Materials Design and Preparation Technology of Hunan Province,China
文摘Abstract： With the substitution of part Mg in LaMg3 by Cu, the elastic constants CH and C12 increase while C44 decreases, implying an enhanced Poisson effect and smaller resistance to 〈001〉（100） shear. Furthermore, the bulk modulus B increases, while the shear modulus G, elastic modulus E and anisotropie ratio A are reduced. The calculated Debye temperature of LaCuMg2 is lower, implying the weaker interaction between atoms in LaCuMg2. Then, the stress-strain curves in entire range and the ideal strength at critical strain are studied. The present results show that the lowest ideal tensile strength for LaMg3 and LaCuMg2 is in the 〈100〉 direction. The ideal shear strength on the 〈 1 ^-1 0〉（110） slip system of LaMg3 is greater than LaCuMg2. The density of states and charge density distribution are further studied to understand the inherent mechanism of the mechanical properties.
