新型相变储能材料研究进展

介绍了相变材料的种类、特点以及储能机理,重点论述了新型相变材料的研究发展,对于复合相变材料和胶囊化相变材料做了较为详细的说明,概括了相变材料的主要研究方向.     

空调方案优化与CAD

本文对常用制冷和空调方式的几个主要因素进行量化，提出因素权重系数概念，以反映空调方案设计阶段的客观条件和主观设计思想。运用计算机辅助设计，所选方案可行、优越     

A practical robust nonlinear controller for maglev levitation system

In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller, a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step. Based on the coupled model, the stresses of the modules are analyzed, and it is pointed out that the inherent nonlinearity, the inner coupling, misalignments between the sensors and actuators, and external disturbances are the main issues that should be considered for the maglev engineering. Furthermore, a feedback linearization controller based on the mathematical model of a maglev module is derived, in which the nonlinearity, coupling and misalignments are taken into account. Then, to attenuate the effect of external disturbances, a disturbance observer is proposed and the dynamics of the estimation error is analyzed using the input-to-state stability theory. It shows that the error is negligible under a low-frequency disturbance. However, at the high-frequency range, the error is unacceptable and the disturbances can not be compensated in time, which lead to over designed fluctuations of levitation gap, even a clash between the upper surface of electromagnet and lower surface of guideway. To solve this problem, a novel nonlinear acceleration feedback is put forward to enhancing the attenuation ability of fast varying disturbances. Finally, numerical comparisons show that the proposed controller outperforms the traditional feedback linearization controller and maintains good robustness under disturbances.     

Self-excited vibration problems of maglev vehicle-bridge interaction system

The self-excited vibration problems of maglev vehicle-bridge interaction system were addressed, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the coupled model containing the quintessential parts was built, and the mechanism of self-excited vibration was explained in terms of energy transmission from levitation system to bridge. Then, the influences of the parameters of the widely used integral-type proportion and derivation（PD） controller and the delay of signals on the stability of the interaction system were analyzed. The result shows that the integral-type PD control is a nonoptimal approach to solve the self-excited vibration completely. Furthermore, the differential-type PD controller can guarantee the passivity of levitation system at full band. However, the differentiation of levitation gap should be filtered by a low-pass filter due to noise of gap differentiation. The analysis indicates that a well tuned low-pass filter can still keep the coupled system stable.     

基于Pro/E的远程零件参数化设计系统研究

提出了一种远程设计机械零部件的新方案.利用VC+ +对Pro/E进行二次开发,将开发的程序封装成COM组件,利用Pro/E进行参数化建模,通过ASP技术调用COM组件实现远程参数化设计.以斜齿圆柱齿轮为例说明机械零部件远程设计系统的实现过程.     

利用聚合氯化铝铁处理电镀废水的研究

电镀废水是污染严重的废水之一,采用絮凝的方法处理电镀废水,操作简单,经济适用.合成无机高分子絮凝剂聚合氯化铝铁处理电镀废水,可降低处理成本,提高絮凝效果.探讨了pH值以及投药量对絮凝效果的影响,并与聚铁、聚铝的絮凝效果作了比较研究.结果表明,聚合氯化铝铁兼有聚合铝和聚合铁的优点,形成的絮凝体大而重,并且沉降速度快,适用的pH值范围也更广,絮凝效果较聚铁、聚铝更为优异,而且用药量少,具有明显的价格优势.     

稀土变质消除铝合金压铸件中硬质点

初生硅和AlSiMnFe金属间化合物是造成铝合金压铸件中硬质点区域的主要因素,常规钠盐变质不能细化初生硅和Fe相,含有一定比例La,Ce,Pr,Nd和Yb的特殊配制的稀土合金不仅能细化共晶硅,而且细化初生硅并改善Fe相形貌,其中初生硅可细化到小于10μm,因此能有效消除铝合金压铸件中的硬质点区域。     

浅谈双侧壁导坑法在工程中的应用

根据穿黄隧洞进口段(35m)工程特点,进行隧洞开挖及支护设计,考虑到穿黄隧洞进口段重要性,而且洞身较短,经建设各方讨论决定,洞口段采用双侧壁导坑法,本文重点阐述双侧壁导坑法及轻型井点降水在工程中的应用。     

浅谈退水洞进口侧盾构安装扩挖段施工技术

退水洞开工以来,因地下水位高、围土力学性能差等原因,施工进展缓慢。为扭转不利局面。经业主和监理工程师批准,在退水洞进口侧以"敞开式盾构法"替代当前使用的"矿山法",进行退水洞洞身开挖支护。为满足盾构机组装需要,对进口侧掌子面前方洞段做扩大开挖处理,开挖支护后实施临时性钢筋混凝土衬砌,确保盾构组装期间的施工安全。     

基于ICA的控制回路故障诊断方法

针对控制回路中各种设备的监测信号之间存在较强的关联性和非高斯分布的特点,首次将独立分量分析法(ICA)用于控制回路的故障诊断中。分别选取回路中控制器输入和输出、执行器输出、变送器输入和输出作为信号观测点,选择控制回路正常运行状况的数据进行ICA建模,获得I2和SPE统计限,当控制回路某个元件发生故障时可以通过统计量的变化对其进行监测。此外,还采用均值贡献率进行故障点定位,有效降低了故障的误诊率。