基于轨迹模式空间解耦及模式能量序列的振荡分析(二)算法及应用

基于状态空间中的模式解耦,及在时域中按其摆次分段,分析振荡能量的时序演化特性。利用互补群惯量中心—相对运动(CCCOI-RM)保稳变换,将非简谐振荡的多机轨迹严格映射为一系列映象上的时变单机系统轨迹,并通过后者在逐次摆动期间振荡能量的演变来刻画原多机系统的振荡行为,在时变单机映象系统的外力—位置平面上分析振荡能量的时空转换,量化其非保守性。文中分别以映象系统轨迹上的动态中心点(DCP)处的动能,及最远点(FEP)处的势能来反映该模式在过去半摆中的振荡总能量;以两者组成的能量序列反映该空间振荡模式的时变性。通过理论分析及数值仿真证实:在描述哈密顿单机系统振荡行为时,轨迹摆次能量序列与特征根分析完全一致,而在分析非哈密顿的单机系统或一般的多机系统时,轨迹摆次能量序列可以克服平衡点特征根的众多缺陷。     

浅阱中双组份玻色- 爱因斯坦凝聚体基态的稳定性研究

应用变分法研究了囚禁在有限深势阱中的双组份玻色-爱因斯坦凝聚体基态的稳定性,结果显示:在有限深势阱中有可能获取稳定的双组份凝聚体,但须满足囚禁原子数的临界条件和基态能量塌缩的临界条件.通过变分法计算还得到了波包的宽度、能量与相互作用系数之间的函数关系,并发现凝聚体之间的相互作用对其稳定性具有非常重要的作用.     

危害计算机信息系统安全犯罪法律适用疑难问题研究

文章根据最高人民法院、最高人民检察院最新出台的危害计算机信息系统安全犯罪司法解释的相关规定,深入分析了侵害信息网络安全犯罪的定罪量刑标准实践把握、单位犯罪司法认定等法律适用疑难问题,运用网络犯罪刑法原理,提出危害计算机信息系统安全犯罪案件中的司法认定规则。     

On repairable earthquake resisting archetypes with a view to resiliency objectives and assisted self‐centering

Performance‐based seismic design, as an alternative to conventional methods of approach, has served engineers and the public rather well during the last two decades. Neither approach guaranties catastrophic collapse prevention nor post‐earthquake realignment and repairs (PERR) due to major seismic events. As a result, most code‐compliant buildings can be regarded as relatively safe but practically disposable. The paper presents a new philosophy that leads to sustainable design of new structures and the upgrading of existing earthquake resisting moment frames. Repairability‐based design (RBD) relies on softening and control rather than strength and resistance to elevate seismic performance to economically viable, physical collapse prevention, damage control, and post‐earthquake realignment and repairs. The new approach was inspired by design led analysis (DLA), performance control (PC), and recent developments in rocking core‐moment frame design. DLA is a displacement based method of analysis with built‐in results. PC is the ability to design a structure in such a way as to expect predetermined modes of response at certain stages of loading, extents of damage, and drift ratios. This paper advocates higher performance objectives than current codes of practice do. Several demonstrative examples have been provided.     

横掠气流作用下波形板壁降膜破裂分析

以边界层理论为基础,基于独立假设建立了波形板通道内降液膜在横向气流驱动下沿屈折角横向偏移的二维边界层模型。通过量纲分析和理想层流假设进行模型简化及边界层方程求解,建立了横向切应力驱动下波形板壁降膜破裂的力平衡模型并给出破膜速度的临界准则,模型包括波形板通道几何参数、气液两相物性及流动参数等多种因素的影响,与本文实验结果和已有理论模型进行对比,所建模型能够更准确地预测液膜发生破裂的临界条件。进一步的量纲分析表明惯性离心力、气流剪切力、壁面黏性力和表面张力共同决定着液膜的运动、变形直至破裂,由它们之间的平衡关系可以确定液膜的稳定与否。     

一种基于竞选领导策略的改进粒子群算法

针对标准粒子群算法由于粒子多样性的大量丧失而导致的算法易陷入局部最优解,收敛精度不高的问题,提出一种基于竞选领导策略的改进粒子群算法,该算法在全局最优粒子的领导能力丧失时,通过引进细菌觅食算法的趋化算子对精英粒子进行优化,然后选出更具领导能力的粒子作为新的领导粒子来带领种群跳出局部最优解,以增强算法的全局搜索能力。通过四个典型函数的测试,结果表明改进算法在较好保留了标准粒子群算法快速收敛优点的前提下,有效地预防了早熟现象的产生,提高了收敛精度。     

基于进化遗传算法的优化计算

针对经典遗传算法在优化计算中存在的弊端,提出进化遗传算法.在染色体基因位编码方式、交叉与变异算子、适合度函数设计、候选解染色体选取方式及收敛准则等方面做了改进.通过对极难优化的Shekel类函数等的优化计算,说明该算法具有良好的全局搜索能力和较快的收敛速度.     

强酸与弱酸混合溶液pH值计算方法的讨论

前言强酸（碱）、一元弱酸（弱碱）、多元酸（碱）、两性物质以及弱酸及其共轭碱（HA＋A－）混合地中的PH值计算方法已有准确的理论计算法,但强酸和一元弱酸（或强碱和一元弱碱）的混合溶依其PH值却无详尽的理论计算法。故对此理论计算进行了数学分析,得出了理论计算公式及近化计算的检验判据,井进行了验证,两者相互吻合。卫理论分析及数学模型的提出在水溶液中,强酸可完全电离jJH3”O,当其浓度＞10‘一1／l一时,强酸在水溶液中的［H＋］为：【H”I—C（设C为强酸摩尔浓度）伯厂／11－‘一VIH才中W自周IZ麻侯世的【H”I不…     

聚磺纳米乳液钻井液在临盘街206井的应用

街206井是胜利油田临盘临南洼陷街斜2鼻状构造高位上采用聚磺纳米乳液钻井液完成的第一口二开中深井,完钻井深3 980 m。该区块在已往的钻井过程中均出现井壁失稳严重垮塌的现象,为了满足钻井施工的需要,经室内综合分析评价优选出适合该区块的钻井液配方,该配方总体性能优良,具有良好的流动性,较强的携砂能力和润滑效果,并在街206井应用获得成功。     

Fracture toughness study for a brittle rock subjected to mixed mode I/II loading

A semi-disk specimen containing an angled edge crack has been used in the past for conducting fracture tests on a brittle rock named Johnstone [Fracture testing of a soft rock with semi-circular specimens under three-point bending. Part 2—mixed mode. Int J Rock Mech Min Sci Geomech Abstr 1994b;31(3):199–212]. The test specimen is appropriate for investigating brittle fracture when the rock samples are subjected to the combined effects of tension and shear along the crack line. However, the experimental results reported in Lim, Johnston, Choi, Boland [Fracture testing of a soft rock with semi-circular specimens under three-point bending. Part 2—mixed mode. Int J Rock Mech Min Sci Geomech Abstr 1994b;31(3):199–212.] are inconsistent with all of the well-known theoretical criteria available for predicting mixed mode brittle fracture. In this paper, a modified criterion is used to provide accurate predictions for the reported experimental results. The modified criterion makes use of a three-parameter model (based on K_I, K_II and T) for describing the crack tip stresses. It is shown that the non-singular stress term T has a significant role when the rock fracture tests are conducted on the semi-disk specimens.