交通设计在城市道路工程设计中的应用

随着经济的发展，交通设计是解决大城市交通拥挤的一种有效措施。以北京市京开高速公路桥下道路改造工程设计为例，阐述了交通设计在城市道路工程设计中是如何应用的，以期对其它正在进行道路交通建设的城市具有参考作用。     

矿用隔爆型三相异步电动机提高能效的设计与分析

针对当前矿用电机效率偏低的状况及造成偏低的因素，并具体结合矿用隔爆型电机YB2-315L1-4的改进设计，分别从设计、原材料采用、制造等角度进行了研究，并结合试验给出了对铁心损耗、铜耗、机械损耗等详细的试验数据分析，提出了较为有效的设计方法和技术措施，确定了新的设计方案，样机的试验结果验证了设计方法的有效性，对提高矿用隔爆型三相异步电动机的能效具有实际的指导意义。     

论我国电力电子产业发展

电力电子产业是我国工业领域的一个基础产业,是装备制造业的一个分支。这一点未必能得到很多人的认同,但是,从目前电力电子技术广泛应用和渗透情况已经可以得出这个结论。     

中国结·塞上结回汉——银川火车站方案设计

在城市越来越失去特色的今天,为了找回对城市的印象,我们必须将地域文化融入到建筑设计中来.     

A simple method for purification of bromelain in a thermosensitive triblock copolymer-based protection system and recycling of phase components

In the work, we chose stem bromelain as a model to investigate the storage and purification of bromelain from pineapple peel. Extraction of bromelain from pineapple peel using a two-stage aqueous two-phase extraction system composed of a thermoseparating copolymer EOPOEO and K₂HPO₄. Bromelain predominantly partitioned to the EOPOEO-rich phase and then re-extract to the top dilute phase. The recovery of enzyme activity (68.6%) and purification factor (6.53) were determined under optimum conditions. The EOPOEO-rich phase and salt were recycled, and the recovery of enzyme activity could reach up to 60%. This method has been proved to obtain highly purified and stable bromelain.     

螺旋管埋弧精焊工艺研究

试验研究了X80管线钢埋弧精焊工艺。通过对不同内外焊参数下多丝埋弧焊焊缝成形的研究,得到一组合理的焊丝搭配方案;利用焊缝和热影响区的金相组织照片分析了焊后接头的组织组成;通过试样的拉伸、弯曲、夏比冲击试验和接头硬度试验,对接头的力学性能进行了相应的分析和研究。     

Robust and minimum norm partial quadratic eigenvalue assignment in vibrating systems: A new optimization approach

The partial quadratic eigenvalue assignment problem (PQEVAP) concerns reassigning a few undesired eigenvalues of a quadratic matrix pencil to suitably chosen locations and keeping the other large number of eigenvalues and eigenvectors unchanged (no spill-over). The problem naturally arises in controlling dangerous vibrations in structures by means of active feedback control design. For practical viability, the design must be robust, which requires that the norms of the feedback matrices and the condition number of the closed-loop eigenvectors are as small as possible. The problem of computing feedback matrices that satisfy the above two practical requirements is known as the Robust Partial Quadratic Eigenvalue Assignment Problem (RPQEVAP). In this paper, we formulate the RPQEVAP as an unconstrained minimization problem with the cost function involving the condition number of the closed-loop eigenvector matrix and two feedback norms. Since only a small number of eigenvalues of the open-loop quadratic pencil are computable using the state-of-the-art matrix computational techniques and/or measurable in a vibration laboratory, it is imperative that the problem is solved using these small number of eigenvalues and the corresponding eigenvectors. To this end, a class of the feedback matrices are obtained in parametric form, parameterized by a single parametric matrix, and the cost function and the required gradient formulas for the optimization problem are developed in terms of the small number of eigenvalues that are reassigned and their corresponding eigenvectors. The problem is solved directly in quadratic setting without transforming it to a standard first-order control problem and most importantly, the significant “no spill-over property” of the closed-loop eigenvalues and eigenvectors is established by means of a mathematical result. These features make the proposed method practically applicable even for very large structures. Results on numerical experiments show that the proposed method considerably reduces both feedback norms and the sensitivity of the closed-loop eigenvalues. A study on robustness of the system responses of the method under small perturbations show that the responses of the perturbed closed-loop system are compatible with perturbations.     

Publication and Distribution of Chinese Standard and Quality Books

1.A Brief Introduction to SPC Standards Press of China (SPC),founded in October,1963,is the largest publisher of standard and quality products in China.It publishes national standards,trade standards,and audio,video,electronic,and network products.