不断延伸的服务解答市民疑问 公交集团相关部门负责人做客《政府与百姓》栏目

党的群众路线教育实践活动开展以来,公交集团本着“正视矛盾不回避,坚持开门搞活动”的原则,密切联系群众,就公交营运、服务方面的问题与市民乘客进行面对面的沟通与交流,通过开门纳谏、积极整改,努力提高服务群众的能力和水平。     

Experimental study on frictional and sealing performances of packing rings in an oil-free gas compressor

To enhance the reliability and to extend service life of packing rings, tribological and sealing performances are investigated based on the experimental results. Friction force, leakage rate and power consumption of three materials of pressure packing seals are measured in a refitted vertical gas compressor. The rings are made of common filled polytetrafluroethylene (Filled PTFE), PTFE reinforced with 30% mass fraction carbon fiber (30%CF+PTFE), and carbon-carbon composites infiltrated with PTFE (C/C+PTFE), respectively. It is found that packing rings will periodically vibrate with the periodic vibration of pressure packing after the travel direction of motion abruptly turns to the reverse direction. Furthermore, the amplitude of vibration slows down with the increasing crank angle. Approximate value of friction force is available by multiple-point fast Fourier transformation (FFT) employed to process the experimental results by reducing the impact of vibration to a great extent. Of three materials of rings employed in experiments, Filled PTFE presents minimal leakage rate accompanied with maximum power consumption. And 30%CF+PTFE exhibits minimum friction power and moderate leakage rate. As for C/C+PTFE, its high mechanical and thermal properties are favorable factors to enhance the ability of operating under high pressure and velocity and to improve the wear resistance. Unfortunately, this also leads to a large leakage rate. Comprehensive consideration should be taken into to evaluate the availability, reliability and service life for a type of packing ring under dry running conditions.     

用结构化非线性最小范数法识别包装系统模态参数

考虑到包装系统的复杂性,可将包装件建模为多模态系统.对结构化非线性最小范数法进行改进,推导出了识别系统自由响应的零点和留数的迭代法,该方法采用以Prony方法识别出的系统的零点和留数为迭代起点,模拟结果表明：该方法与Prony方法相比具有更好的精确性,为准确识别包装系统各模态的参数打下基础.     

手把手汽修（七） 常见的刹车故障（下）

《驾驶园》杂志携手专业汽车修理厂开设＂手把手汽修专栏＂,介绍常见的客车故障及维修办法。本栏目少去了专业性很强的说教,更多的是便于驾驶司机亲手实践的操作说明,意为读者搭建一个自己动手排除故障的DIY平台。本栏目信箱：xywang@jiacheren.com     

定位包装论--关于产品包装的新思维

包装既有“容纳”产品的功能,也有“文饰”产品的作用。对于汽车、火车、飞机、轮船等无须容纳的产品,则可以通过文饰进行包装。显然,提出“定位包装”的概念,不但是包装概念的升华,而且是包装观念的发展。     

Two Bandwidth Packing Algorithms for the Centralized Wireless Network and Their Average-case Analysis

This paper presents a detail analysis of two bandwidth packing algorithms, used for processing connection requests in the centralized wireless network. Each call comes with a specific bandwidth request. A request can be satisfied only if there is sufficient bandwidth available during resource scheduling and allocation. Unsatisfied requests were held in a queue. The metric of bandwidth utilization ratio was used to quantify the performance of our algorithms. By theoretical analysis, our algorithms can improve the average bandwidth usage ratio significantly, about 8%~10% without adding much computation complexity. Moreover, our algorithms outperform next fit with fragmentation (NFF) algorithm when the bandwidth resource is scarce. In this paper, the contributions follows: Introducing bandwidth packing problem into wireless network; Proposing two new bandwidth packing algorithms for wireless network where the complicate scheduling algorithms are prohibited; Studying the average performance of our algorithms mathematically, which agree well with the simulation results.     

F关于《国际船舶安全载运包装的辐放射性核燃料、钚和高放射性废料（INF）规则》修正案生效的公告

国际海事组织海上安全委员会第79届会议于2004年12月10日以MSC178（79）号决议通过了《国际船舶安全载运包装的辐放射性核燃料、钚和高放射性废料（INF）规则》（以下简称“INF规则”）的修正案。     

校园快递包装的绿色回收物流优化建议

大学生是重要的网上购物群体,使高校成为产生快递包装的重要场所。本文以大学校园为研究对象,首先分析大学和全国快递包裹的消费状况和特点,其次找出快递包装回收过程中遇到的问题,最后针对其存在的问题提出快递包装回收物流发展的建议,对我国的可持续发展和低碳环保绿色回收物流理念有着重要意义。     

陈总编直线

电动助力转向可以打到底陈总编好!在2011年第2期《汽车知识》的陈总编直线第七小项问题中,提问者的电控助力转向,我理解的应是电动助力转向,也就是用电动机作为转向助力源的转向系统,这类电动助力转向有很多优点,其中之一就是可以将转向随便打到底,不用在乎烧损液压泵的问题,因为它根本就没有液压系统。不知我说的是否正确。