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。     

低松装密度水雾化铜粉工艺的研究

本文研究了氧化 还原法生产铜粉的新工艺 ,该工艺是通过氧化还原将水雾化铜粉加以表面改性 ,形成海绵状的粉末 ,显著降低水雾化铜粉的松装密度 ,这种铜粉既具有电解铜粉低的松装密度 ,又具有水雾化铜粉高的流动性。讨论了氧化时间、氧化温度对铜粉松装密度的影响。本工艺是一种新型环保、节能、可替代电解法生产铜粉的先进工艺     

基于关键节点和多播节点的多播路由算法

在视频会议等多播应用中，降低多播树网络费用非常重要。本文提出了基于关键节点和目的节点的多播路由KDDMC算法。由于在算法中优先考虑采用关键节点，实现更多链路的共享，从而降低网络费用。在随机网络上的仿真结果表明，KDDMC算法的多播树网络费用优于SPH算法。同时证明了KDDMC算法的复杂度为O(n^3)，且利用所提出的路由表算法易于分布式实现。     

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.     

主动约束层阻尼板结构动力学建模研究

将有限元法和GHM法相结合，给出了建立主动约束层阻尼（ACLD）板结构动力学模型的新方法。建模时，考虑到粘弹材料（VEM）的纵向位移影响，采用GHM方法描述VEM的本构关系，解决了VEM的力学特性随温度和频率变化的难点，避免因VEM的复杂本构关系而产生的微分积分方程。算例表明本文给出的建模方法是准确的，ACLD结构能够有效控制结构振动。     

柴油机针阀体的乙炔低压渗碳

乙炔低压渗碳可以有效地避免在真空渗碳过程中产生炭黑和焦油，同时由于乙炔具有较高的供碳能力，使这一技术尤其适用于针阀体这样的小直径深盲孔零件。