大容量高密度体全息数据存储

基于晶体体全息存储机理 ,采用半导体泵浦固体激光器取代氩离子激光器作为系统光源 ,设计并构建了小型体全息存储器 ,实现了 15 0 0幅等衍射效率高分辨率全息图的记录和复现 ,其存储容量大于 1 1Gbit ,存储密度大于1 4Gbit/cm3 。     

A New Cooperation Mechanism of Kinesin Motors when Extracting Membrane Tube

Membrane tubes are important functional elements for living cells. Experiments have found that membrane tubes can be extracted from giant lipid vesicles by groups of kinesin. How these motors cooperate in extracting the membrane tube is a very important issue but still unclear so far. In this paper, we propose a cooperation mechanism called two-track-dumbbell model, in which kinesin is regarded as a dumbbell with an end (tail domain) tethered on the fluid-like membrane and the other end (head domain) stepping on the microtubule. Taking account of the elasticity of kinesin molecule and the excluded volume effect of both the head domain and the tail domain of kinesin, which are not considered in previous models, we simulate the growth process of the membrane tube pulled by kinesin motors. Our results indicate that in the case of strong or moderate exclusion of motor tails, the average number of motors pulling the tube can be as high as 9 and thus motors moving along a single microtubule protofilament can generate enough force to extract membrane tubes from vesicles. This result is different from previous studies and may be tested by future experiments.     

A New Higher Order Shear Deformation Model for Static Behavior of Functionally Graded Plates

In this paper, a new displacement based high-order shear deformation theory is introduced for the static response of functionally graded plate. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Numerical illustrations concerned flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The validity of the present theory is investigated by comparing some of the present results with those of the classical, the first-order and the other higher-order theories. It can be concluded that the proposed theory is accurate and simple in solving the static behavior of functionally graded plates.     

Flow Characteristics of Flapping Motion of a Plane Water Jet Impinging onto Free Surface

A submerged turbulent plane jet in shallow water impinging vertically onto the free surface will produce a large-scale flapping motion when the jet exit velocity is larger than a critical one. The flapping phenomenon is verified in this paper through a large eddy simulation where the free surface is modeled by volume of fluid approach. The quantitative results for flapping jet are found to be in good agreement with available experimental data in terms of mean velocity, flapping-induced velocity and turbulence intensity. Results show that the flapping motion is a new flow pattern with characteristic flapping frequency for submerged turbulent plane jets, the mean centerline velocity decay is considerably faster than that of the stable impinging jet without flapping motion, and the flapping-induced velocities are as important as the turbulent fluctuations.     

Neural control of vocalization: Respiratory and emotional influences

Previous research has shown that a region of the midbrain, the periaqueductal gray matter (PAG), is critical for vocalization. In this review, we describe the results of previous investigations in which we sought to find out how PAG neurons integrate the activity and precise timing of respiratory, laryngeal, and oral muscle activity for natural-sounding vocalization using the technique of excitatory amino acid microinjections in cats. In these studies, all surgical procedures were carried out under deep anaesthesia. In the precollicular decerebrate cat two general types of vocalization, classified as voiced and unvoiced, could be evoked by exciting neurons in the lateral part of the intermediate part of the PAG. The patterns of evoked electromyographic activity were strikingly similar to previously reported patterns of human muscle activity. Coordinated patterns of activity were evoked with just-threshold excitation leading to the conclusion that patterned muscle activity corresponding to the major categories of voiced and voiceless sound production are represented in the PAG. In a parallel series of human and animal experiments, we also determined that the speech and vocalization respiratory patterns are integrated and coordinated with afferent signals related to lung volume. These data have led to the proposal of a new hypothesis for the neural control of vocalization: that the PAG is a crucial brain site for mammalian voice production, not only in the production of emotional or involuntary sounds, but also as a generator of specific respiratory and laryngeal motor patterns essential for human speech and song     

用自适应流线网格计算定常超声速流场

提出一个用自适应流线网格计算定常超声速流场的数值方法。Friedrichs-Lax格式推广到任意四边形网格,在迭代过程中得到速度场后,从流线方程计算流线的位置,最后算出由本方法得到高分辨率结果     

平行板间方势阱偶极流体的结构性质研究

在密度泛函理论(DFT)框架下, 应用改进的基本度量理论(MFMT)表达硬球作用对自由能泛函的贡献, 根据统计力学理论结合加权密度近似(WDA)表达偶极作用对自由能泛函的贡献,得到了方势阱偶极流体在平行板间的密度分布表达式, 计算了偶极流体在两平行板间的密度分布, 并探讨了方势阱深度和宽度对体系密度分布的影响. 此外, 通过体系密度分布, 进一步分析了方势阱宽度和深度以及板间尺度与溶剂化力的关系.     

黏弹性熔体充模流动诱导残余应力模拟

流动诱导残余应力是塑料制品产生应力开裂以及翘曲变形等现象的重要原因,对成型过程中流动诱导残余应力研究具有重要意义.推导了基于黏弹性eXtended Pom-Pom本构关系的能量方程,进而建立了描述黏弹性流体非等温充模流动的气-液两相模型.用同位网格有限体积法进行了求解,得到了凝固层和剪切速率分布,给出了充填结束时影响制件力学性能的流动诱导残余应力.结果表明,型腔中凝固层的厚度与注射速率有关,注射速率越大,充模时间越短,凝固层越薄.在制品表层紧邻模壁的地方,剪切速率和残余应力几乎为零;在制品次表层的位置,制件内剪切速率和流动残余应力也较高;而在远离模壁的地方,剪切速率和流动残余应力也较小.     

对酒精-水小孔周期性泄流的实验与分析

介绍酒精-水周期性泄流实验的装置,阐述实验现象,记录实验数据并进行归纳整理,用计算机软件描绘图形,通过反复实验和分析,得出与以往盐水-水等不一样的酒精-水小孔周期性泄流的振荡规律.     

多峰离子源的三维数值模拟优化与设计

本文理论计算了多峰离子源永磁体, 采用二体碰撞模型处理电子之间的库仑碰撞, 运用空碰撞方法处理电子与氢元素相关粒子碰撞, 开发了全三维粒子模拟-蒙特卡罗模拟算法, 并采用此软件对热门多峰离子源JET-60U的两种优化设计模型进行数值模拟研究, 探索了两种离子源空间分布特性和体积负氢离子产率相关问题, 提出了负氢离子源设计的基本思想: 适当调整离子源多峰磁场分布情况可以输出均匀离子束; 适当调整引出磁场大小和离子源结构, 可以达到离子束空间均匀性和高产率兼顾的效果.