曲轴TR法成形的三维有限变形弹塑性有限元模拟

大型曲轴的全纤维盛开有工艺是保证曲轴能够在复杂的应力状态下正常工作的一种有效的工艺方案。由于其成形过程复杂,变开吕的应力场和应变场很难用实验方法确定。本文基于ＡＮＳＹＳ工作平台,利用开发的三维有限变形弹塑性有限元程序,并利用开发的三维网格重划功能模块,模拟了曲轴的ＴＲＩ地成形过程,得到了曲轴在成形全过程中的应力场、应变场以及载荷位移曲线,为制定合理的成形工艺方案,优化模具设计,提高成形质量,以及提     

脉冲涡流TR探头解析模型的快速求解方法

作为分析脉冲涡流响应的常用工具,解析模型因具有物理意义明确、精度高、计算速度快等优点而得到了广泛关注;近年来,随着脉冲涡流阵列探头的应用,对其阵列单元--即激励和接收线圈非同轴的Transmitter-Receiver阵列单元(以下简称TR探头)的解析分析需求迫切;而当前关于TR探头的解析模型大多数将试件缺陷等效为大面积壁厚减薄缺陷,模型精度较低;为提高TR传感器解析模型的求解精度,将构件缺陷等效为平底盲孔缺陷,建立了含平底盲孔构件脉冲涡流TR探头的解析模型,且提出了一种快速求解该模型解析解的方法:首先,通过分析典型模型解析解的形式,发现其由广义反射系数、线圈系数等乘积组成,且广义反射系数仅与构件结构有关,线圈系数仅与探头有关;然后,参考已有的含平底盲孔构件同轴式探头检测模型和均匀壁厚减薄缺陷的TR探头模型,分别获取广义反射系数和线圈系数解析表达式;最后,将其组合得到含平底盲孔构件脉冲涡流TR探头的解析解;通过和实验数据做比较验证了上述解析解的正确性;所提出的方法可应用到其他脉冲涡流解析模型的快速求解中,降低解析模型的求解难度。     

Vertically installed Venturi tubes for wet-gas flow measurement: Possible improvements to ISO/TR 11583 to extend its range of applicability

Venturi tubes are commonly used for wet-gas flow measurement, and the majority of commercial wet-gas flow meters generally include a Venturi tube installed vertically with embedded secondary instrumentation. The presence of the liquid causes an increase in the measured differential pressure and results in the Venturi tube over-reading the actual amount of gas passing through the meter. Most of the research in the literature is focused on the investigation of the over-reading for horizontally oriented Venturi tubes, thus limiting the development of over-reading correlations for vertical installation. An experimental campaign was recently conducted at the TÜV SÜD National Engineering Laboratory (NEL) high-pressure wet-gas loop, where three Venturi tubes of the same nominal diameter (4”) but different throat to inlet diameter ratio (0.4, 0.6, 0.75) were tested, installed vertically after a blind tee. The results of this experimental campaign are presented in this paper and the effects of various parameters (line pressure, gas Froude number, diameter ratio) on the over-reading are briefly discussed. It is shown that the over-reading correlation included in the ISO/TR 11583:2012 and developed for horizontally oriented Venturis, is not applicable to vertically oriented Venturis. However, if modified, the correlation included in the ISO/TR 11583 is capable of meeting its stated uncertainty limits for the experimental data presented here for vertically installed Venturis.     

Can mobile TV be a new revolution in the television industry?

The development within the mobile communications industry has provided a new mechanism for individuals to watch television programs via mobile device, known as mobile television (m-TV). Considering that m-TV is an emerging technology among traditional television services where critical success factors depend on user-centered, it is important to understand users' behavioral intention (BI). Unlike previous studies which have mainly focused on flow experience, perceived value, motivation and social cognitive theories, this study examines user-centered factors of technology readiness (TR) and technical support and training (TST). Therefore, 244 valid data were tested using partial least squares structural equation modeling (PLS-SEM) to measure both reflective and formative constructs based on the proposed framework. Findings reported that performance expectancy (PE), effort expectancy (EE) and TST have a positive and significant impact on BI. TR however has a negative relationship with BI. In addition, TR was also found to influence PE and EE. Similarly, TST has a direct effect factor on EE and EE was a significant determinant of PE. The findings of this study not only provide guidance for future researchers, but also valuable insights for designers, marketers and system providers of m-TV to tailor their services in the near future.     

Improving the peak‐to‐average power ratio of the single‐carrier frequency‐division multiple access system through the integration of tone injection and tone reservation techniques

This paper proposes a new method for reducing the peak‐to‐average power ratio of the single‐carrier frequency‐division multiple access system. The method is an integration of the tone injection (TI) and tone reservation (TR) techniques. A recommended method that uses TI to improve TR's low data transmission rate problem that is caused by the reservation of subcarriers. Additionally, to reduce the massive amount of computation required by the combined needs of TI and TR, an iterative flipping algorithm was adopted for this purpose. Simulation results indicate that the proposed method is not only capable of effectively improving the peak‐to‐average power ratio–reduction efficiency of the single‐carrier frequency‐division multiple access system but it can also improve the data transmission rate of the conventional TR technique.     

一种新型高效收发组件的研究与设计

对多层微波数字复合基板和宽禁带高效电路进行了研究,并设计了一种基于高效宽禁带器件和多层微波数字复合基板技术的收发组件。该收发组件的发射功率大于10W,发射通道射频功率效率超过60％,大大高于传统收发组件的效率。     

基于TR-069协议的配置管理功能研究与应用

首先,提出了一种远程配置管理功能模块的设计方案,然后详细介绍该模块的TR-069参数模型设计原则和数据配置文件读写保护机制,最后介绍该设计方案的应用实例。经验证,所提供的设计方案可有效地增强设备的可用性和可管理性。     

时间反转技术在超宽带穿墙雷达中的应用

将时间反转(Time Reversal,TR)技术与阵列成像技术相结合,通过数值仿真研究了该技术在超宽带穿墙雷达(Through-the-Wall-Radar,TWR)探测中的应用。仿真分别考虑了单层和多层墙体环境下隐蔽的单目标和多目标探测问题,并将相应的时间反转成像与改进的后向投影(Improved Back Projection,IBP)算法成像进行了对比。结果显示,时间反转技术能够为超宽带穿墙雷达探测系统提供更高分辨率的探测结果。     

基于TR069的IPTV远程升级系统的设计与实现

随着IPTV机顶盒大批量进驻用户家庭,电信运营商对机顶盒的业务变更及版本升级有了更高的需求。为了满足这一需求,本文设计了一套方案来实现对IPTV机顶盒的远程在线升级。这套方案基于TR069协议,采用Yc／S及客户端／服务器模式。在机顶盒开机时通过TR．069协议来控制流程,判断机顶盒的版本号是否需要升级。如需要升级,则发布命令使机顶盒从升级服务器上下载升级包,然后在本地完成升级。实际测试结果表明,该方案可以实现安全稳定的远程在线升级,最后总结了该方法的优点和今后进一步的研究重点。     

一种Ka频段瓦片式TR组件子阵集成方案

提出了一种Ka频段瓦片式TR组件子阵集成方案,采用多层电路技 术、内层带状线功分器、优化脊波导口径、同型端口集中分布等手段大幅提高集成度,采用 高可靠性小截面脊波导实现模块间高性能垂直互联。给出了TR组件子阵电路布局设计,对小 截面脊波导传输特性、脊波导-微带探针过渡和集成功率分配网络等关键无源电路进行了设 计、仿真和测试。测试结果表明其性能和尺寸满足Ka频段TR组件子阵集成要求。