孔隙水压力与恒定时间对砂岩变形的实验研究

探讨三峡库水位在145-175 m之间涨落及蓄水时水压对岩（石）体的变形特性影响。以实验为基础,进行了不同轴向应力（1σ=55.54,34.18和12.82 MPa）条件下,周期孔隙水压力（Pmin=2 MPa,Pmax=6 MPa）与上、下限恒定时间（ΔT=120和240 s）作用下砂岩的变形特性实验。通过分析1ε-T与p-T关系曲线和p-1ε滞回曲线,可知：1ε-T砂岩曲线呈连续正弦波形演化,当孔隙水压力加载时,应变减小;上限恒定时,应变持续减小到谷值;卸载时,应变逐渐增大;下限恒定时,应变持续增大到峰值。砂岩p-1ε滞回曲线的2个阶段变化,一是微孔隙压密阶段,未形成明显的滞回曲线;二是孔隙水压力耦合阶段,形成了稳定的滞回曲线,表现形式由疏变密,并且稳定的滞回曲线呈逆时针演化。还对比了不同轴向应力和不同恒定时间条件下,每个p-1ε滞回曲线的四区段（加载段、卸载段、上限恒定段和下限恒定段）的Δε-n关系曲线。     

Cycling hardening and serration yielding of Fe-Ni-Cr alloy at high temperature under out-phase TMF

Behaviour of hardening and serration yield of a Fe-Ni-Cr alloy under isothermal cycling (ISC) and out-phase TMF was studied on the basis of varied hysteresis loops. Cycling hardening and serrated yielding for ISC depend on the temperature and the total strain range, stronger hardening with serrated yielding at higher strain range under ISC at 600 °C, but no hardening and serrated yielding occurred under ISC at 800 °C. Stronger hardening with stress serration occurred at the thermal path going to the lowest temperature, no stress serration occurred at the highest temperature under the out-phase. The hardening also depends on the total strain range, higher total strain range with lower cycling temperature resulted in a stronger hardening and remarkable serration yielding behavior. Weaker hardening without serrated yielding occurred at near 800 °C may due to an obvious cycling stress drop under out-phase TMF. Change in the shape of the hysteresis loops also expresses the degree of the damage of the tested alloy under out-phase and ISC.     

新型钢铅组合耗能器性能试验及参数优选

为了考察新型钢铅组合耗能器(NCSLD)的力学性能和提高其耗能能力,利用电液伺服压剪试验机对NCSLD耗能器进行力学性能试验,采用ANSYS实体建模的方法对耗能器进行大量的数值分析,并对性能试验和数值分析的结果进行对比,研究耗能器的滞回特征参数与其6个几何参数之间的关系,回归出二者之间的公式.提出评价耗能器性能优劣的标准及其附加条件,并以此标准为依据,利用均匀设计法和遗传算法分别对耗能器的6个几何参数进行优选.结果表明遗传算法的选优效果要好于均匀设计法,同时得到一系列性能良好的NCSLD耗能器.     

低轨道卫星通信中越区切换信道分配算法研究

该文根据低轨道卫星通信中,呼叫请求到达的特点,以带滞后结构的马尔可夫链模型来模拟信道的占用和分配状态,对新呼叫阻塞率和切换呼叫中断率进行评估。仿真结果表明:较低通信量负载时,这种信道分配策略简单有效,在保证切换呼叫中断率小于0.05%的情况下,呼叫阻塞率大大降低,同时提高资源利用率。     

三维超材料的非线性电、磁响应特性

理论研究了埋入在非线性介质中的由金属线和谐振环构成的具有三维周期性结构的超材料的有效电、磁响应,计算了该种超材料的有效磁导率和介电常数实部和虚部随外场的变化关系.结果表明,这种超材料有效磁导率和介电常数的实部对外磁场的响应具有回滞效应.在一定条件下,这种结构的属性可在右手材料、电单负材料与磁单负材料之间转换,且这种转换可适当选择在某些特定频率范围内的外磁场强度的方式控制.     

Modeling large reversible electric-field-induced strain in ferroelectric materials using 90° orientation switching

Reversible large electric-field-induced strain caused by reversible orientation switchings in BaTiO3 is modeled using the Landau's theory of phase transition. A triple well free energy function is constructed. Each of its minima is associated with one of the polarization orientations involved. Nonlinear constitu- tive laws accounting for reversible orientation switchings and electrostriction effects are obtained by using thermodynamic equilibrium conditions. Hysteretic dynamics of one-dimensional structures is described by coupled nonlinear differential equations. Double hysteretic loops in the electric and me- chanic fields are both successfully modeled. Giant reversible electrostriction is modeled as a conse-quence of reversible orientation switchings via electro-mechanical couplings. Comparisons with ex-perimental results reported in literatures are presented.     

HYSTERESIS OF GAS-LIQUID MASS TRANSFER IN A TRICKLE BED REACTOR

1 INTRODUCTIONTrickle bed reactors are widely used in the process industry,particularly in petroleumhydroprocessing operations,and have been extensively studied by chemical engineers.In atrickle bed reactor,the gas and liquid flow cocurrently down through the packed bedand undergo chemical reactions.However,there exist multiple hydrodynamic stateswhich correspond to either uniform or,in most cases,nonuniform radial distributionof the gas and liquid flows in the packed section.Moreover,the hydrodynamic state is     

椭圆形钢铅耗能器性能及振动台试验

针对工字型钢铅组合耗能器直角区域容易应力集中、过早屈服断裂退出工作的问题,提出一种由钢和铅两种材料组成的椭圆形钢铅耗能器,这种耗能器加工简便且水平两个方向都具有良好耗能性能.首先,对椭圆形钢铅耗能器中钢板的平面应力进行分析.其次,对椭圆形钢铅耗能器进行力学性能试验;利用有限元分析软件ANSYS建立椭圆形钢铅耗能器的非线性计算模型进行数值分析并与性能试验结果进行对比.最后,对一个安装和不安装椭圆形钢铅耗能器的六层钢框架结构模型进行振动台对比试验.研究结果表明:数值分析结果与性能试验结果吻合良好,本文建立椭圆形钢铅耗能器数值计算模型的方法正确;椭圆形钢铅耗能器滞回曲线饱满,具有良好耗能能力;椭圆形钢铅耗能器对多层结构的地震反应具有较好减震效果.     

丝网编织金属橡胶的静态力学性能研究

针对沉孔型金属橡胶制品展开研究,采取了控制变量和对比分析的2种研究方法,对金属橡胶制品的静态压缩和剪切性能进行了系统全面的实验研究。通过实验结果给出了在不同结构参数下金属橡胶制品静态性能的变化关系,同时得到了金属橡胶制品在压缩过程中的线性-软特性-硬特性的变化过程。针对不同状态下的减振耗能情况对金属橡胶减振的机理进行深入的剖析,进而得知相对密度与变形幅值是影响金属橡胶减振器减振能力的2个重要参数。     

Ni含量对TiNi形状记忆合金相变行为的影响

用示差扫描热分析仪和光学显微镜系统研究了Ｎｉ含量对ＴｉＮｉ形状记忆合金Ｒ相和Ｍ相相变温度，相变热，热滞的影响。结果表明：在加热和冷却过程中，Ｔｉ－３３．３％Ｎｉ和Ｔｉ－７５．０％Ｎｉ不发生相变；ＴＭ，ΔＭ，ΔＨＭ和ΔＨＲ是Ｎｉ是含量的函数，ＴＲ和ΔＲ基本为一定值，与Ｎｉ含量有关。