规则波作用下垂直圆柱局部波浪力

在ＫＣ为４.０～３５，雷诺数Ｒｅ为６×１０＾３～２×１０＾４参数范围内就规则波作用下垂直圆柱局部波浪力进行了实验研究，给出横向力随ＫＣ数类型变化的划分，基于Ｓｏｔｋｅｓ二阶波理论和Ｍｏｉｒｓｏｎ公式得到圆柱阻力系数ＣＤ，惯性力系数ＣＭ和最大升力系数ＣＬｍａｘ沿桩柱的分布及其随ＫＣ数的变化规律，结果表明，在波表面间歇区桩柱的局部水动力系数变化显著，越向波峰位水动力系数ＣＤ和ＣＬｍａｘ越减小，而ＣＭ值却越增高.

Some features of the turbulence produced by rising air bubbles in water

Presented in this paper is an experimental study on the characteristics of the turbulence produced by rising air bubbles in water. The measurements of turbulent velocities were made by using visualization technique of particle streak and computer image processing of the flow field. The turbulence features have been examined, showing that the rising bubble-produced turbulence can be approximately modeled by homogeneous turbulence as in the case of grid turbulence in air.

Pyrex玻璃/铝多层阳极键合界面结构与力学分析

采用公共阳极法实现了Pyrex玻璃与铝多层晶片的静电键合,对玻璃/铝/玻璃阳极接合界面的组织结构及其连接机理和力学特征进行了重点研究。分别利用微拉伸测试设备和ANSYS软件分析了连接区的力学性能和残余应力分布特征。分析认为键合区由玻璃-过渡层-铝组成,过渡层为Al_2O_3-SiO_2复合氧化物。玻璃/铝界面的微观组织和元素分布均以铝为对称轴呈对称分布。在玻璃/铝/玻璃多层连接区,键合界面附近的残余应力和应变呈对称分布,多层结构的对称性有利于缓解接头应变和应力,表明应用公共阳极法可实现多层玻璃/铝/玻璃的良好键合。

用反射式达曼光栅产生飞秒激光双脉冲

采用反射式达曼光栅建立了一种产生飞秒激光双脉冲的新装置．由于采用反射式结构，避免了材料色散和吸收导致的脉冲畸变，并构建了一台二次谐波一频率分辨光学开关装置对产生的双脉冲进行了测量．实验结果表明可以实现脉冲强度相等、时间宽度相同、不同间隔的双脉冲输出．产生双脉冲的装置在飞秒激光领域有着应用的价值．

Optical two-dimensional SW-banyan network: Optical implementation, routing control, and determination of permissible permutations

A 2-D SW-banyan network is introduced by properly folding the 1-D SW-banyan network, and its corresponding optical setup is proposed by means of polarizing beamsplitters and 2-D phase spatial light modulators. Then, based on the characteristics and the proposed optical setup, the control for the routing path between any source-destination pair is given, and the method to determine whether a given permutation is permissible or not is discussed. Because the proposed optical setup consists of only optical polarization elements, it is compact in structure, its corresponding energy loss and crosstalk are low, and its corresponding available number of channels is high. (C) 1996 Society of Photo-Optical Instrumentation Engineers.

Relaxation of yeast mitochondrial functions after whole-genome duplication

Mitochondria are essential for cellular energy production in most eukaryotic organisms. However, when glucose is abundant, yeast species that underwent whole-genome duplication (WGD) mostly conduct fermentation even under aerobic conditions, and most can

中国的生物多样性保护与自然保护区

生物多样性保护是当今社会的热点话题"而建立自然保护区是对其进行 就地保护的最有效措施+目前中国自然保护区对生物多样性保护起到了巨大的 作用"但由于其建设速度较快"在管理,科研和开发方面不配套"还存在一系列问 题"必须在宏观上对保护区进行科学规划"在资金投入上拓宽渠道"在管理方面 引入新的机制"才能使自然保护区对生物多样性的保护起到积极的作用+

流式细胞术在细胞凋亡研究中的应用

流式细胞术做为一种高新生物技术,在动物医学的各个领域,包括细胞生物学、病毒学、肿瘤学、免疫学和病理学中都得到广泛应用,为细胞凋亡研究提供了有效的技术手段。该技术具有简便、快速、多参数分析等优点,可针对细胞在凋亡时产生的一系列形态学、生物化学及分子生物学性质的变化,包括细胞皱缩,核染色质凝聚,细胞膜通透性改变,Caspases 激活,线粒体跨膜电位降低,膜磷酯酰丝氨酸外化,胞质 Ca2+ 浓度升高,DNA片段化及含量变化等特点,进行定性、定量测试分析,从而实现对细胞凋亡的准确测定。

A Low Power Baseband Chain for CMMB Application

This paper presents experimental results of an analog baseband circuit for China Multimedia Mobile Broadcasting (CMMB) direct conversion receiver in 0.35um SiGe BiCMOS process. It is the first baseband of CMMB RFIC reported so far. A 8(th)-order chebyshev low pass filter (LPF) with calibration system is used in the analog baseband circuit, the filter provides 0.5 dB passband ripple and -35 dB attenuation at 6MHz with the cutoff frequency at 4MHz, the calibration of filter is reported to achieve the bandwidth accuracy of 3%. The baseband variable gain amplifier (VGA) achieves more than 40 dB gain tuning with temperature compensation. In addition, A DC offset cancellation circuit is also introduced to remove the offset from layout and self-mixing, and the remaining offset voltage and current consumption are only 6mV and 412uA respectively. Implemented in a 0.35um SiGe technology with 1.1 mm(2) die size, this tuner baseband achieves OIP3 of 25.5 dBm and dissipate 16.4 mA under 2.8-V supply.

目标检测中的空间位置约束模型

针对目前常见的星形模型等易受部件缺失影响的问题,提出一种空间位置约束模型.该模型以目标中心作为参考点,衡量所有局部特征之间的位置关系,避免了特殊结点缺失带来的不利影响.基于模板中目标的表面特征和形状因素构造空间位置约束模型,利用待检测目标的表面特征信息形成相关假设,通过假设检验定量地衡量目标出现的位置及可能性,并提出了一种搜索目标中心位置的加速算法.实验结果表明,该空间位置约束模型不受部件缺失的影响,性能稳定.