大牵引力连续油管牵引器设计及仿真

针对水平井作业工具输送困难的问题,同时在满足钻磨作业的基础上,设计了基于液压伸缩原理的连续管牵引器。为满足井下牵引器对大牵引力、井下适应性、通过性、越障能力的要求,创新提出了自激式液压控制回路(无电缆),来实现牵引器协调控制相关动作,采用一种楔形燕尾滑槽弹性支撑结构,以适应井径变化同时满足障碍通过性,使用SolidWorks三维画图软件、 ADAMS(automatic dynamic analysis of mechanical systems)运动仿真等软件建立连续油管牵引器的虚拟样机,验证其运动性能。结果表明:该牵引器在5~1/_2″套管中能够平稳行进,牵引力最大可达到10 000 N,满足设计标准。     

The decoherence-free in multi-coupled quantum computing system

A subdynamics theory framework for describing multi-coupled quantum computing systems is presented first. A general kinetic equation for the reduced system is given then, enabling a sufficient condition to be formulated for constructing a pure coherent quantum computing system. This reveals that using multi-coupled systems to perform quantum computing in Rigged Liouville Space opens the door to controlling or eliminating the intrinsic de-coherence of quantum computing systems. Foundation item: Supported by the National Natural Science Foundation of China (79970121) Biography: Liu Gui-Ping (1964-), male, Lecturer. Research direction: quantum networks.     

油酸系阴离子型缓蚀剂性能的研究

在实验室合成含有磷酸酯基的油酸系阴离子型缓蚀剂,用失重法研究了其在标准溶液中的缓蚀作用,发现具有优良的缓蚀性能。其水溶液喷涂在金属表面,干后形成一层保护薄膜,防潮防锈,并能抑制已锈蚀金属继续生锈。     

DNA甲基化与基因调控

ＤＮＡ甲基化或去甲基化,改变了ＤＮＡ分子构象,导致某些重要基团的隐蔽或暴露,削弱或增强了ＤＮＡ与蛋白质因子的结合能力,从而改变了基因表达．     

A sperm GPI-anchored protein elicits sperm-cumulus cross-talk leading to the acrosome reaction

The acrosome reaction has long been thought to be induced by the zona pellucida. Here we report the identification and function of a novel human sperm glycosylphosphatidylinositol (GPI)-anchored membrane protein, NYD-SP8. The release of the protein during sperm-egg interaction and its binding to the cumulus, the first layer of egg investment, elicits cross-talk between the gametes and produces calcium dependant release of progesterone, which lead to the acrosome reaction. An in vivo mouse model of NYD-SP8 immunization is also established showing a reduced fertility rate. Thus, contrary to accepted dogma, our study demonstrates for the first time that, prior to reaching the zona pellucida, sperm may release a surface protein that acts on the cumulus cells leading to the acrosome reaction, which may be important for determining the outcome of fertilization. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 11 August 2008; received after revision 18 December 2008; accepted 22 December 2008     

探讨区域雷达网雷达部署数目与检测概率关系

频率编码脉冲是一种大时宽带宽信号,具有良好的距离分辨性能,并可拥有较窄的瞬时带宽。推导了频率编码脉冲信号与步进频率编码脉冲信号的模糊函数,分析了其距离、速度分辨性能及其相应关系,并对频率编码脉冲信号模糊函数的旁瓣抑制问题进行了讨论,结果表明,采用遗传算法得到的频率编码工程优化值,能较好解决目标距离、速度的联合测量问题。     

一种基于特殊训练序列的TH-UWB信号同步捕获算法

超宽带信号的快速同步捕获是实现UWB系统的一个重大挑战。提出了一种基于特殊训练序列的同步捕获算法,它只需对接收信号进行符号速率的积分清洗运算,然后根据信号的依次截取实现同步参数的搜索估计。该算法有效地提高了密集多径信道下极窄脉冲能量捕获,并且降低了运算复杂度和同步捕获时间。通过计算机仿真评估了在密集多径信道下,训练序列长度对捕获精度和系统误码性能的影响,以及捕获性能、系统误码性能与信噪比的变化关系。仿真实验表明,在训练序列长度为16、32时误码性能曲线和理想同步情况下已十分接近。这说明与传统的数据辅助算法相比,该算法只需要较短的训练序列就可以实现较理想的系统性能,从而提高了系统的带宽利用率。     

会计信息失真的原因及控制措施

文章分析了企业会计信息失真的原因及特点,指出了其危害性并论述了防止会计信息失真的措施.     

基于异步电机工作模型的设计

综述了异步电机的分析模型,讨论了什么时候、什么场合,宜选用哪种模型,并根据异步电机模型的功能和用途,详细分析了设计用模型、诊断仿真用模型和控制用模型等几种常见类型.     

发电运行状态带式输送机驱动装置的位置确定

分析了煤矿采区上山采用下端驱动的带式输送机易发生输送带打滑和制动停车失控而造成堆料的原因,并提出了适合于井下生产的另一种安全可靠的下端驱动方式的带式输送机。