科创中国

In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

无线传感器网络(WSN)是基于IEEE802.15.4标准的一个无线多跳网络协议标准,它本身并不支持IPv6协议.为了整合WSN和IPv6网络来实现异构WSN之间的互联,6LoWPAN定义了如何在IEEE802.15.4网络上传输IPv6报文,但这并不支持WSN节点和IP网络设备的端到端互连.本设计的网关可以实现WSN网络和IPv6主机之间通过IPv6协议进行实时交互操作.通过实验证明本网关可以实现不同WSN网络节点和IPv6主机之间的通信,允许IPv6主机读取WSN节点数据并触发相应的动作.

It is a common phenomenon that the cracks originating from a hole can cause structural damage in engineering.However,the fracture mechanics studies of hole edge crack problems are not sufficient.The problem of an elliptical hole with two collinear edge cracks of unequal length in an infinite plate under uniform tension at infinity is investigated.Based on the complex variable method,the analytical solutions of stress functions and stress intensity factors are provided.The stress distribution along the axes and the edge of the elliptical hole is given graphically.The numerical results show that there is obvious stress concentration near the hole and cracks,and the stresses tend to applied loads at distances far from the defect,which conform to Saint-Venant's principle.Hence,the stress functions are proved to be right.Under special conditions,the present configuration becomes the Griffith crack,two symmetrical cracks emanating from an elliptical hole,two cracks of unequal length emanating from a circular hole,a crack at the edge of a circular hole,or a crack emanating from an elliptical hole.Compared with available results,stress intensity factors for these special shapes of ellipses and cracks show good coincidence.The stress intensity factor for two cracks of unequal length at the edge of an elliptical hole increases with the crack length and the major-to-minor axis ratio of the elliptical hole.The stress distribution in an infinite plate containing an elliptic hole with unsymmetrical cracks is given for the first time.

The flammability, smoke emission behavior and mechanical properties of two oligomeric aryl phosphates [bisphenol A bis(diphenyl phosphate) (BDP) and resorcinol bis(diphenyl phosphate) (RDP)] combined with magnesium hydroxide (MH) in polyamide 6 (PA6) have been investigated. Combining 5 wt% BDP, 50 wt% MH imparts a limiting oxygen index (LOI) of 40.9% and UL94 V-0 rating to PA6, meanwhile the peak rate of smoke release (pRSR), total release of smoke (TSR) and Izod notched impact strength are 41%, 33% and 233% relative to the corresponding value of 55 wt% MH without BDP, respectively. Dynamic mechanical analysis (DMA) indicates that the improvement of toughness attributes to the enhanced compatibility between MH and PA6 by adding BDP. Furthermore, based on the comprehensive analysis of thermogravimetry (TG), cone calorimeter and SEM-EDX investigations, possible flame retardancy and smoke suppression mechanisms were revealed. Besides the fuel dilution and barrier effect of MH, the combination of MH and RDP shows an additional flame inhibition effect. The combination of MH and BDP results in a dominant condensed phase barrier effect which leads to obvious reduction on smoke emission and flammability.

首先对物流配送及相关理论进行了综述,提出了共同配送模式在广西-东盟物流中的应用,同时,对广西现行的自营配送模式与共同配送模式进行了比较,并从成本、路线、经营主体等方面进行了定性、定量分析,由此,得出了自营配送模式存在成本高、路线不完善、经济主体单一等一系列问题,而共同配送模式更适合于广西物流发展的现状,并提出了共同配送的三种组织模式在广西物流应用中的优势和劣势.最后,提出了共同配送模式在广西物流配送应用中需要注意的问题及其对策.

笔者将一台离线的SF6变压器外壳作为试验容器,对变压器内SF6气体进行局部加热试验,全程对气体分解产物进行跟踪检测,将模拟过热点温度下的检测结果进行分析研究,找出SF6气体过热点温度与气体分解产物的变化关系,得出了SF6气体在加热温度不断升高的过程中顺序产生HF、SOF2、SO2、SO2F2的结论,同时确定了上述各分解气体在加热过程中出现的温度区间,旨在给有效评估SF6设备状态、对设备内部故障性质进行判断提供参考.

本文介绍了一种基于HART协议的智能温度变送系统.该系统由AVR单片机、HART芯片SD2015B、A/D转换芯片AD421构成,支持多种传感器信号输入,通过电流环路实现模拟和数字信号的同时传输,能够应用在工业控制、智能仪器仪表等方面,具有较强的实用性.

在利用多项式进行GPS水准拟合时,若转换点位于控制点外部,则由于法方程系数矩阵病态而导致结果不可信.使用岭估计可有效改善法方程的病态性,保证解的稳定性.以不同的岭估计方法对实例进行估计,证实L-曲线法在点位分布不合理时该估计方法较最小二乘法、岭迹法以及经验公式法更有效,精度更高.

原位杂交技术的广泛应用为各学科的研究带来突破性进展,其对组织标本的常规处理要求越来越高.在日常病理组织处理过程中,甲醛和二甲苯作为病理常规试剂被大量应用.但是传统试剂具有强烈的刺激性和一定的毒性,不利于环保和工作人员的健康.作者尝试应用环保型GS(green specimen)组织样本制备套液制作组织蜡块,并应用原位杂交技术检测HPV L1壳蛋白的表达,以探讨GS环保试剂对