鞍山市青少年活动中心裙楼结构设计及体会

通过一个工程实例,介绍高层建筑框架结构设计中遇到的工程问题的处理方法     

Friction compensation design based on state observer and adaptive law for high-accuracy positioning system

Friction is one of the main factors that affect the positioning accuracy of motion system. Friction compensation based on friction model is usually adopted to eliminate the nonlinear effect of friction. This paper presents a proportional-plus-derivative (PD) feedback controller with a friction compensator based on LuGre friction model. We also design a state observer to observe the unknown state of LuGre friction model, and adopt a parameter adaptive law and off-line approximation to estimate the parameters of LuGre friction model. Comparative experiments are carried out among our proposed controller, PD controller with friction compensation based on classical friction model, and PD controller without friction compensation. Experimental results demonstrate that our proposed controller can achieve better performance, especially higher positioning accuracy.     

基于分形接触的湿度对静摩擦因数影响分析

采用分形接触模型推导并计算了由水膜的弯月面效应引起的附加静摩擦力,得到了由水膜的弯月面效应引起的附加静摩擦力的表达式,表明随着分形维数D的增大和分形粗糙度G的减小,计算的附加静摩擦系数增大,同时随着相对湿度的增加,水膜厚度增加,附加的静摩擦系数增加.     

基于数字差动组合式测量法的微摩擦性能测试

在微观领域的滑动摩擦性能测量中，基于一种新的数字差动式测量原理，利用顺、逆时针时独立测量出的拉力，在计算时使这两个测量结果相减，从而使测量过程中的各种等值误差相互抵消．因此，在理论上消除了这些测量误差对最终结果的影响．在实际应用中，该原理能明显减少温度漂移等误差因素对测量结果的影响，显著提高测量系统的重复性．     

线摩擦驱动带式输送机动力分析及动态设计

简述线摩擦驱动原理，分析并实测弹性波在输送带中的传播速度；在分析线摩擦驱动带式输送机动力过程的基础上，提出带式输送机的动态设计方法及其应用程序。     

板料变形中两种摩擦模型的比较

本文应用刚塑性有限元方法，分别采用修正的常剪应力摩擦模型和库仑摩擦模型，对板料在半球形冲头下的拉胀变形和在平底圆柱冲头下的拉延变形过程进行计算，并上述两种摩擦模型的作用机制以及它们板料塑成形过程的影响进行了研究。通过分析、比较与实验验证，表明库仑模型比常剪应力模型更为适合板料成形过程模拟的摩擦描述。     

煤矸石堆积对矿区土壤中重金属的影响

以开采历史达百年煤炭城市-淮南矿区为例,研究煤矸石长期堆积对矿区土壤造成的重金属污染.从不同开采历史的矿井区选择7条土壤采样线,系统采集煤矸石堆附近的土壤样品,使用电感耦合等离子体全谱直读光谱仪(ICP-AES)对土壤中主要有害元素(Cu、Ni、Pb、Zn、Sn、Cr、Co)进行分析,并用沉积物标样(LKSD-1)控制分析质量.研究结果表明煤矸石长期风化、淋溶已导致其堆边土壤中重金属发生累积性污染;不同矿井区土壤中重金属含量呈现随煤矸石堆积和风化时间长短呈递减趋势,且Cu、Co、Zn、Ni、Pb相对较易迁移,其含量在部分矿井区土壤中超过国家土壤一级污染标准,但均未超过二级污染标准,这说明煤矸石中重金属向周围土壤的迁移是一个缓慢过程.     

Axonal transport of neurofilaments in normal and disease states

Neurofilaments are among the most abundant organelles in neurones. They are synthesised in cell bodies and then transported into and through axons by a process termed 'slow axonal transport' at a rate that is distinct from that driven by conventional fast motors. Several recent studies have now demonstrated that this slow rate of transport is actually the consequence of conventional fast rates of movement that are interrupted by extended pausing. At any one time, most neurofilaments are thus stationary. Accumulations of neurofilaments are a pathological feature of several human neurodegenerative diseases suggesting that neurofilament transport is disrupted in disease states. Here, we review recent advances in our understanding of neurofilament transport in both normal and disease states. Increasing evidence suggests that phosphorylation of neurofilaments is a mechanism for regulating their transport properties, possibly by promoting their detachment from the motor(s). In some neurodegenerative diseases, signal transduction mechanisms involving neurofilament kinases and phosphatases may be perturbed leading to disruption of transport. Received 11 July 2001; received after revision 30 August 2001; accepted 31 August 2001     

PC管桩在宁德车站软基处理中的应用

分析与总结了宁德车站中PC管桩的设计与施工中的重点，提出了PC管桩在实际运用中的一些建议。