矿井提升系统的强非线性振动

矿井提升机在提升重物的过程中,由于质量和刚度的变化引起的系统固有频率十分缓慢的变化,因此考虑钢绳质量的矿井提升机系统是一个慢变参数振动系统．本文首先应用Kuzmak—Luke的多尺度法得到有一般非线性弹性力的强非线性振动系统解的周期性条件及用Jacobi椭圆函数表示的平方非线性振动和立方非线性振动的首阶渐近解．其次,将得到的结果分别应用于有平方、立方非线性弹性力的质量慢变的矿井提升系统．最后,将理论结果应用于某个矿井提升系统,应用算例的渐近解和数值解的比较表明本方法是有效的．     

低序级不整合圈闭描述关键技术——以东营凹陷南部斜坡带为例

济阳坳陷东营凹陷南部斜坡带古近系发育多期低序级不整合,是形成地层圈闭（油藏）的有利区带。由于低序级不整合经历的地质时间短,不整合面上、下地层的产状和岩石学特征差异小,常规测井和地震响应差别不明显,难以识别和描述不整合面和上、下地层尖灭线,影响了地层油藏的勘探评价。为此,提出了基于有序数列最优分割的测井综合分层曲线法,与高分辨率地震时频分析相结合,形成低序级不整合面识别的有效技术;研发了地震“DNA”检测方法,将地震数据转换为字符表达式,创建地层模式“基因”,在字符域中自动搜索,实现地层尖灭线的精细描述。该方法应用于东营凹陷南部斜坡带的地层圈闭评价,取得了很好的效果。     

A CL mode detector for rapid catalyst selection and environmental detection fabricated by perovskite nanoparticles

La(1-x)Sr(x)MnO3 (x = 0, 0.2, 0.5, 0.8) nanoparticles were synthesized and their chemiluminescence (CL) and catalytic properties of CO oxidation were determined. We mainly investigated the influences of filter band length, flow rate of gas, test temperature, catalyst compositions, and particle size on CL intensities and catalytic activities of the catalysts. The catalysts were characterized by means of XRD, TEM, N2 adsorption isotherm, CO-TPD, and O2-TPD, etc. It was found that the strong CL response signals occurred over these perovskites nanoparticles; and that CL properties of the catalysts were well correlated with the reaction activities. These nanoparticles can be used to fabricate a stable gas detector due to a high activity and stability of perovskite structure. CL mode could be a rapid and effective method for the selection of new catalysts from thousands of materials, as well as for the detection of environmental deleterious gases.     

Testing and Modeling of the Dynamic Response Characteristics of Pulsating Heat Pipes during the Start-up Process

Pulsating heat pipes(PHPs) are two-phase heat transfer heat pipes with high heat transfer capability and simple structure. Heating power is an important factor that affects the start-up response characteristics of PHPs. The operational characteristics during the start-up and stable operating stages were studied through experiments, and the corresponding dynamic response model under a specified heating power was established based on experimental data and flow pattern in the tube. The starting time, starting temperature, and dynamic response characteristic parameters at a certain heating power were calculated by the dynamic response model. The response characteristics of working fluid during the stable operation of PHPs were deduced based on the dynamic response curve of PHPs during the non-operational and stable operation stages. The response characteristics of PHPs for the step effect(given heating power) were quantitatively described by amplification factor K and time constant τ, thereby presenting the basis for the study on heat and mass transfer mechanisms of PHPs from non-operational to steady operation stage. Results showed that the minimum thermal resistance and the minimum time constant of the PHP are approximately 0.28 °C/W and 75, respectively, obtained at a heating power of 160 W. Moreover, these results indicated that the dynamic response of PHPs demonstrates a favourable performance and rapidly reaches another stable working state when their heat transfer performance is stable. However, the dynamic response time constant of pure fluids decreases when the quantity of the liquid working fluid in the PHP decreases with the increase in heating power.     

广州新电视塔结构健康监测应变修正计算的研究

大型钢筋混凝土结构做长期的结构健康监测,需要综合考虑混凝土的收缩徐变影响.对应变传感器采集的原始应变数据做适当的修正,可提高监测的准确度.本文以广州新电视塔结构健康监测中应变修正的计算为例,阐述了美国混凝土学会(ACI)推荐的收缩徐变分析理论在结构健康监测中的应用,并结合实验室的试件测试数据,修正徐变和收缩的具体计算公...     

Single-stage aging behaviour and precipitate evolution in a high Zn-containing Al–9.78Zn–2.02Mg–1.76Cu alloy

Property evolution in a high Zn-containing Al–9.78Zn–2.02Mg–1.76Cu alloy treated at 120°C, with the microstructure subjected to under-aging (UA), peak-aging (PA) and over-aging (OA), is investigated. Precipitate size distributions and distances between neighbouring precipitates are determined. Results indicate that a certain time is required to reach peak hardness and yield strength, and that peak values can be sustained for a relatively long time. As the aging time increases, the conductivities increase persistently. As the alloy temper varies from UA to PA to OA, the main matrix precipitates change from ‘GPI zone and GPII zone and η′ phase’ to ‘GPII zone and η′ phase’ and then to η′ phase. Meanwhile, the precipitate size distribution becomes broader, and the average precipitate size increases.     

Effect of Zn addition on two-step aging behaviour of Al–Mg–Si–Cu alloy

This study investigates the effect of Zn addition two-step behaviour in an Al–Mg–Si–Cu alloy. During pre-aging at 100°C for 3?h, the Zn can partition into clusters because of the strong Zn–Mg interaction, prompting the formation of clusters. During subsequent artificial aging at 180°C for up to 240?min (peak hardness condition), the Zn does not significantly partition into clusters or precipitates, and the majority of Zn remains in the Al matrix. However, the presence of Zn in the matrix stimulates the transformation from clusters to GP zones to β′′ phases. The enhanced formation of GP zones and β′′ phases correlates well with the remarkable age-hardening response.     

门限签名方案的研究及其安全性分析

对谢君琴等人提出的无可信中心的门限签名方案进行了安全性分析,指出了该方案不能抵抗合谋攻击和已知消息攻击,不具有可追踪性。针对上述问题,在谢君琴等人的方案的基础上提出了一个无可信中心的门限签名方案：由签名组织者发起对消息的签名,限制门限签名的发布权于签名组织者,从而抵抗合谋攻击和已知消息攻击;建立追踪方程,实现签名者的追踪。通过安全性分析,证明了所提出的方案具有抗合谋攻击、在已知消息攻击下和选择消息攻击下的存在性不可伪造性、可追踪性等安全性能。与谢君琴等人的方案相比,所提出的方案降低了计算复杂度,提高了签名执行效率。     

聚合物纳米电介质材料研究进展及其在埋入式无源元件中的应用概述

聚合物纳米电介质材料由于其出色的机械加工特性、电可调制特性已成为当今高密度封装技术等诸多学科的前沿领域。通过在聚合基体中引入高介电陶瓷或纳米导电颗粒形成具有高介电常数的复合材料,并通过印刷电路板(Printed Circuit Board,PCB)制备工艺内置于PCB基板内部形成埋入式元件(电容、电感及其他无源元件),这已经在电子系统小型化方面显示出巨大的应用前景。文章综述了高介电纳米聚合物复合材料领域近年来的研究进展,探讨了聚合物纳米复合材料在埋入式电容器、电感器中的应用及埋入式无源滤波器的设计方法、制备工艺以及复合材料的电磁特性对埋入式元件电学性能的影响。