高温高压汽缸连接螺栓松驰损伤失效机理研究

为确保火电厂高温高压状态下的汽缸结合面不漏气,必须对连接螺栓松驰失效进行分析。提出了火电厂高温高压汽缸连接螺栓应力松驰、蠕变损伤及其二者交互作用的特征和机理,以及松驰后的剩余弹性应力不应低于最小密封应力和应控制塑性变形量即不过大也不过早产生。     

大学新生心理咨询个案报告

大学新生初入校门由于环境的变化、学习内容的加深等而出现了紧张、烦躁、失眠、学习效率下降、情绪大起大落等一心理问题，内心痛苦前来咨询。运用认知疗法和放松训练对问题进行分析和诊治，消除不合理的认知及行为模式．使其症状得到缓解。     

一类特殊二次分配问题及其求解

二次分配问题(quadratic assignment problem,QAP)是应用于诸多领域的组合优化NP-难题,许多从实际问题中抽象出来的二次分配问题,其流矩阵与距离矩阵中存在大量零元素,如果在该类二次分配问题的求解中,能够充分利用这些零元素的信息,将大大缩减问题的规模,节省大量运算时间.本文以二次分配问题的线性松弛模型为基础,分别从理论和实验的角度对这类二次分配问题的求解进行了研究,说明了二次分配问题求解中,先行利用零元素信息减小问题规模的可行性和重要性.     

液晶高分子流体在拉伸流动中拉伸粘度的解析计算研究

在液晶高分子熔液挤出过程中,剪切拉伸是主要考虑因素.用液晶高分子B模型本构方程,并考虑取向运动的影响得到拉伸粘度随松驰时间与拉伸率之间的变化关系和曲线.     

一类自适应松弛算法的算法模型

对于一类自适应松弛算法,本文提出了一个算法模型。在一些通常的假定下,证明了该模型生成的序列的收敛性定理。     

丝状液晶非线性光学衍射效应的弛豫时间研究

本文研究了丝状液晶在光感应下产生衍射光束的弛豫时间,找出了与分子重新取向的响应时间相联系的对应关系,对影响弛豫时间的三种重要因素作了理论分析。对MBBA的弛豫时间测量结果与理论计算结果一致。     

伸展运动、热身运动、放松运动的生理学审视

运动员在进行训练或比赛前后都要做不同形式的热身运动和放松活动．因此,了解这些运动的生理学机制,就可以充分发挥其活动的作用,提高运动成绩,延长运动寿命．本文运用人体生理学的原理对伸展运动、热身运动和放松运动进行剖析．     

Enhanced dielectric performance of Dy - substituted YMn2O5 for high-frequency applications

The dielectric performances as well as the effects of Dy³⁺ ions content at A sites of YMn₂O₅ (YMO) [x ​= ​0 (YDM₀) and x ​= ​0.4 (YDM_0.4)] polycrystalline samples were explored. These compounds were synthesized via sol–gel method. X-Ray diffraction and Raman measurements proved the high quality of the compounds that crystallized in an orthorhombic structure with the Pbam space group. Besides, impedance spectroscopy and electrical modulus studies revealed that both samples exhibited a non-Debye's type of relaxation. The decrease of impedance for YDM_0.4 compared to the pure YDM₀, may be attributed to the decrease in charge transfer resistance. Concerning the fit of impedance spectra, they confirmed that both compounds were simultaneously capacitive and resistive. Furthermore, the activation energies obtained from Modulus and complex impedance were proven to be neighboring, suggesting that the relaxation process refers to electron hopping. For each compound, the evolution of ε' and tan ​δ with temperature indicated a clearer relaxor behavior, namely the existence of two relaxations. The first one detected at low temperature is related to the charge carriers hopping between Mn³⁺ and Mn⁴⁺ and the second at high temperature is associated with oxygen vacancies. The reduced hopping rate with Dy³⁺ substitution for Y³⁺ ions at A sites is responsible for the decrease in dielectric constant and dielectric loss. These significant findings demonstrate that these materials can be invested in a fruitful use in UV photo-detector and power applications in high frequency as microwave, millimeter wave signal processing, for civilian, military and space applications.     

金属快速凝固理论及材料制备方法

快速凝固技术是近年来得到广泛发展和应用的新型材料的制备技术，其特点是具有较高的冷却速率和明显的非平衡效应，文章讨论了金属非平衡凝固过程的原理与方法．并对非平衡凝固技术在制备新材料中的应用作详细介绍。     

Radar Cross-Section Measurement Using the Near-Field Single-Frequency Angular-Diversity Technique

1.INTaODUCTIONRadarcross-sectionisaphysicalparametertorepreseDttheabilityofatargettoscsttertheelectromagneticwavefromaradar.IntheoreticalandexperimeDtalstudies,itisknownthatthehighfrequencyscatteringfromanelectricallylargetargetcanbewellapproximatelymodeledasifitisemanatedfromadiscretesetofpointsonthetargetcalledscatteringcenters[l,ZI.Thescatteringcentermodelisconceptuallyconciseanditprovidesasparseabstractionoftheactualcomplextargetfornumerousapplications.ForRCSmeasuremellt,asphericalw…