Architectural Control of Hierarchical Nanobelt Superstructures in Catanionic Reverse Micelles

BaXO₄ (X = Mo, W) nanobelts and a variety of hierarchical superstructures assembled from the nanobelts have been synthesized in a catanionic reverse‐micelle system. The effects of various factors, such as the mixing ratio (r) between the anionic and cationic surfactants, the temperature, and the presence of polymeric additives, on the formation of the nanobelts and their hierarchical assembly have been examined in detail. In particular, r has been shown to be powerful in modulating the formation and assembly of the BaMoO₄ and BaWO₄ nanobelts. Architectural control of the penniform nanobelt superstructures has been readily achieved by changing the experimental parameters. A plausible two‐stage growth mechanism has been proposed for the formation of penniform BaXO₄ nanobelt superstructures in catanionic reverse micelles.     

MHD simulation of high-current subsonic vacuum arc under different distributed axial magnetic fields

Based on two-temperature magnetic hydrodynamic (MHD) model, the influence of saddle-shaped distributed axial magnetic field (AMF, linearly increases along radial position) and bell-shaped distributed AMF (linearly decreases along radial position) on plasma loss and heat flux density to anode in subsonic high-current vacuum arc (HCVA) is simulated and analyzed. According to the simulation results, the saddle-shaped AMF can more effectively inhibit plasma loss from arc column than that of bell-shaped AMF. Comparisons between simulation results and experimental results further verify the correctness of model and simulation.     

8字形管角部裂纹问题研究

冷弯异型管在角部存在应力集中现象，有时存在裂纹倾向。通过对沈阳东洋异型管有限公司一异型管产品——8字形管产生裂纹的原因进行分析，确定了解决方案：①修理轧辊，加大有开裂倾向的内陷角；②选用塑性更好的板材。实践证明，该措施能有效地防止管角角部裂纹的产生。     

油库防爆电气设备运行安全管理注意事项

分析了油库防爆电气设备运行中安全管理应注意的几个事项。     

回龙电站地下厂房开挖施工技术

回龙电站地下厂房设计开挖尺寸为112m×42m×16m(长×高×宽),采用岩壁吊车梁新型结构形式。厂房结构布置自上而下共分6层,结构复杂;施工面相互交叉,干扰因素多,爆破施工安全隐患大。通过精心组织,结合优质的施工技术和周密的措施,较好地完成了开挖任务。图1幅,表3个。     

A NEW LARGE CAVITATION CHANNEL IN CHINA SHIP SCIENTIFIC RESEARCH CENTER

1 .　INTRODUCTIONIntherecentdecades ,itisrealizedthatitisquitenecessarytocarryouttestsathighReynoldsnumberwithalowbackgroundnoiselevelinordertomeetmoreandmoreurgentneedsofmodernnavyandmaritimeindustry .Anewlargecavita tionchannelisdevelopedinCSSRCfortestingcompletehull/ propulsor/appendagesarrange ments[1] .Itrepresentsoneofthelatestintechno logicallyadvancedlargecavitationtestfacilities.Inthefollowingsections ,thefeaturesandthefirsttestresultsofthechannelwillbedescribed .2 .　DICRIP…     

Programmable group-delay module using binary polarization switching

We demonstrate the first programmable group-delay module based on polarization switching. With a unique binary tuning mechanism, the device can generate any differential group delay value from -45 to +45 ps with a resolution of 1.40 ps, or any true-time-delay value from 0 to 45 ps with a resolution of 0.7 ps. The delay varying speeds for both applications are under 1 ms and can be as fast as 0.1 ms. We evaluate both the dynamic and static performances of the device while paying special attention to its dynamic figures of merit for polarization-mode dispersion emulation and compensation applications. Our experiment shows that the device exhibits a negligible transient-effect induced power penalty (<0.2 dB) in a 10-Gb/s nonreturn-to-zero system.     

IEEE 802.11 roaming and authentication in wireless LAN/cellular mobile networks

A wireless LAN service integration architecture based on current wireless LAN hot spots is proposed so that migration to a new service becomes easier and cost effective. The proposed architecture offers wireless LAN seamless roaming in wireless LAN/cellular mobile networks. In addition, a link-layer-assisted mobile IP handoff mechanism is introduced to improve the network/domain switching quality in terms of handoff delay and packet loss. An application layer end-to-end authentication and key negotiation scheme is proposed to overcome the open-air connection problem existing in wireless LAN deployment. The scheme provides a general solution for Internet applications running on a mobile station under various authentication scenarios and keeps the communications private to other wireless LAN users and foreign network. A functional demonstration of the scheme is given. The research results can contribute to rapid deployment of wireless LANs.