无缝钢管形变时效强化的实验研究及应用

通常认为形变时效强化会明显地降低塑性。本文用20MnSi,45,30Mn2钠无缝管进行了不同形变量及时效温度的试验。结果表明:时效强化不一定降低塑性。在某些情况下,400℃时效后,强度和塑性都提高了;或其中某一项指标得到提高而另一项并不降低。对形变时效强化的机理作了初步讨论。     

PHS网络优化探讨

结合工程实际，从网络覆盖、同步、呼叫区划分及交界、资源等4个方面，较为详细地论述了PHS网络的优化问题。     

Thickness and grain size monitoring in seamless tube-making process using laser ultrasonics

The seamless tube-making process often causes wall-thickness variations generally in a helical pattern along the tube length. A laser-ultrasonic system installed immediately after the final operation in tube making provides process monitoring. Tube wall thickness and temperature measurements guide the mill adjustments to achieve the desired tolerances. Using the same ultrasonic signals, additional functionality provides the ability to measure the size of austenite grains. A signal processing approach based on a single echo analysis is used for determining wall thickness and austenitic grain size in relatively thick materials. Discussions review challenges specific to on-line conditions such as limited signal-to-noise ratio. A statistical comparison with metallographic results shows that the laser-ultrasonic grain sizes determined on-line have at least the same accuracy.     

螺丝湾水电站压力斜井取消钢衬设计实践

螺丝湾压力斜井承受４７ ．０～２０３．８ ＫＰａ 内水压力，鉴于山坡陡峻、地形完整，满足最小复盖厚度准则，满足最小地应力准则，设计取消了传统的钢衬设计，采用了钢筋混凝土衬砌设计，实践证明是成功的     

基于Mobile IP的WLAN/GPRS融合网络

首先比较了WLAN和GPRS两种技术的特点；接着提出了一种基于Mobile IP的支持WLAN/GPRS网络无缝漫游的融合方案，它利用WLAN网络与GPRS网络在技术上的互补性，可快速为用户提供支持无缝漫游的数据业务。此方案基于如下基本思想：尽量不对GPRS网络做任何修改，而主要通过对对WLAN网络结构进行调整来实现两者的融合。在描述此方案的主要工作流程时，包括以下方面的内容：移动接点接入/附着、WLAN到GPRS的漫游，GPRS到WLAN的漫游、WLAN网络可用性的判断、计费等。     

Effects of space velocity on methanol synthesis from Co2/Co/H2 over Cu/ZnO/Al2O3 catalyst

The space velocity had profound and complicated effects on methanol synthesis from CO₂/CO/H₂ over Cu/ZnO/Al₂O₃ at 523 K and 3.0MPa. At high space velocities, methanol yields as well as the rate of methanol production increased continuously with increasing CO₂ concentration in the feed. Below a certain space velocity, methanol yields and reaction rates showed a maximum at CO₂ concentration of 5–10%. Different coverages of surface reaction intermediates on copper appeared to be responsible for this phenomenon. The space velocity that gave the maximal rate of methanol production also depended on the feed composition. Higher space velocity yielded higher rates for CO₂/ H₂ and the opposite effect was observed for the CO/H₂ feed. For CO₂/CO/H₂ feed, an optimal space velocity existed for obtaining the maximal rate.     

热轧张减管青线问题的探讨

青线是热轧无缝钢管生产中主要的外表缺陷之一，在总结长期现场实际生产经验的基础上，对产生青线的种种原因进行了探讨，并针对性提出了预防青线的几点措施，这对同类机组减少青线现象具有一定的参考意义。     

穿孔机轧辊设计初探

结合我国新近引进的无缝钢管机组，系统地探讨了二辊斜轧穿孔机的轧辊参数设计原则，给出了主要参数的计算公式和设计中应注意的问题。     

SHARE: seamless handover architecture for 3G-WLAN roaming environment

For the transition from 3G communication systems to 4G communication systems, 3G-WLAN interworking systems can be a reference model for 4G communication systems. In this paper, we identify challenging problems in 3G-WLAN interworking systems and propose a loosely coupled architecture called SHARE. In SHARE, each WLAN hotspot access point (AP) is equipped with a 3G radio transmission module to generate radio signals for control channels of 3G networks in addition to a WLAN radio module. Consequently, base stations of the 3G networks share their control channels with hotspot APs. By monitoring these channels, mobile nodes can easily detect available WLAN hotspots without probe delay for handovers.

社区基础教育设施空间配置评价与优化

在我国城市建设主体越来越多元化,城市居住用地开发和居住区建设日益表现为市场行为主导的格局下,传统的基础教育设施规划模式正不断受到严峻挑战。结合余姚案例,旨在探讨在当前的城市发展背景下,研究基础教育设施的布局配置问题,服务于城市空间的未来拓展和功能优化提升。