旋流式气液分离器内流场的数值模拟

气液分离器作为制冷系统中的关键部件,其分离性能的优劣对系统有着重要的影响。为了研究旋流式气液分离器的分离性能,首先从理论上介绍了旋流式气液分离器的分离机理,列出其主要结构参数,然后基于计算流体动力学(CFD)方法,采用Gambit建模,利用Fluent软件,对旋流式气液分离器进行了模拟仿真,并对进口附近壁面速度场、不同尺寸和进出口截面流场矢量图、纵向剖面气液体积分数分布图等进行了重点分析。仿真结果表明设计是正确、合理的。     

Modelling of spall damage in ductile materials and its application to the simulation of the plate impact on copper

A statistical model of dynamic spall damage due to void nucleation and growth is proposed for ductile materials under intense loading, which takes into account inertia, the elastic-plastic effect, and initial void size. To some extent, void interaction could be accounted for in this approach. Based on this model, the simulation of spall experiments for copper is performed by using the Lagrangian finite element method. The simulation results are in good agreement with experimental data for the free surface velocity profile, stress record behind copper target, final porosity, and void concentrations across the target. The influence of elastic-plastic effect upon the damage evolution is explored. The correlation between the damage evolution and the history of the stress near the spall plane is also analyzed.     

二维颗粒气体在堆积过程中的能量耗散

通过高速摄像的方法观测了玻璃颗粒组成的准二维气态颗粒流的冷凝耗散过程,并和理想情况下的均匀耗散的颗粒流体理论作了比较,实验发现气态颗粒部分在耗散堆积过程中近似地满足高斯分布;从动能的结果来看,实际耗散过程和流体理论所预测的不同.实验发现冷凝分为两个阶段：当动能的贡献以气体颗粒为主时,发现颗粒以恒定的速度堆积,动能耗散主要由其中以气态分布的颗粒的沉积速率α,颗粒温度T和气态部分的平动速度ν_g决定;当气态颗粒数目趋向于0,能量耗散主要来自于密堆颗粒的表面层部分 关键词： 离散体系 耗散性     

一种高速多通道光纤阵列光开关

为了对短时间大视场一维光强信息进行采集,采用编码转换技术和自聚焦透镜矩形阵列设计了光开关,用小口径电光晶体实现了大视场的测量.采用MOS管级联的高压同步电路,使得系统具有结构紧凑、性价比高、寿命长等优点.实验结果表明:开关选通时间100±5 ns,前后沿小于25 ns,消光比1 100∶1.     

Fabrication and observation of nanowire-assemblages of Si-Ge

A few of the interesting structures made by the assemblage of Si-Ge nanowires fabricated by the floating-zone melting-vapor method have been observed. They reveal shapes that are similar to coral, jellyfish and sea anemones. The pre-sintered substrate bar has some large crystalline particles (1–15 μm), which produce sites that are energetically predisposed to nucleation. The peculiar structures created by the assemblage of Si-Ge nanowires form on favored nucleation sites that consist of numerous bundles of nanowires with diameters of 20–50 nm. The periodic variation in the diameter of the bundles of nanowires is a common feature of these structures. In addition, a growth mechanism assisted by the coexistence of Ge and Si-Ge oxides is suggested. The growth process of these assemblages opens up new possibilities for the study of the growth mechanism of Si-Ge nanowires. Received: 25 July 2002 / Accepted: 9 September 2002 / Published online: 17 December 2002 RID="*" ID="*"Corresponding author. Fax: 81-298/59-2736, E-mail: HU.Quanli@nims.go.jp     

The Asymmetric Avalanche Process

An asymmetric stochastic process describing the avalanche dynamics on a ring is proposed. A general kinetic equation which incorporates the exclusion and avalanche processes is considered. The Bethe ansatz method is used to calculate the generating function for the total distance covered by all particles. It gives the average velocity of particles which exhibits a phase transition from an intermittent to continuous flow. We calculated also higher cumulants and the large deviation function for the particle flow. The latter has the universal form obtained earlier for the asymmetric exclusion process and conjectured to be common for all models of the Kardar–Parisi–Zhang universality class.     

可见-近红外光谱的模型转移分类方法

基于光谱技术建立的多元校正模型通常条件下只适用于同一台仪器、相同的测试条件及同批次或同类别的样品.在仪器、测试环境、样品发生变化后,已建光谱模型不再适配,需要进行模型转移.模型转移是限制光谱技术推广应用的关键技术瓶颈,模型转移是否成功直接影响到可见-近红外光谱技术的推广应用,为此,综述了其研究现状,并探讨了其未来发展方...     

CAES离心压缩机可调扩压器调节规律研究

离心压缩机是压缩空气储能系统中关键设备之一,需具备在较宽流量、压力范围内高负荷高效率运行的能力。作为一种变工况调节技术,可调扩压器可以扩大压缩机工作流量范围,改善气动性能。因此,本文以某压缩空气储能系统用离心压缩机为研究对象,通过数值计算方法研究了可调扩压器调节时压缩机性能变化规律。结果表明采用可调扩压器可以有效拓宽压缩机运行特性,工作流量范围扩大44%,压比范围扩大25%.此后,本文采用Kriging模型获得了压缩机综合性能曲线图和不同储能工况需求下扩压器的调节方案及规律,为压缩空气储能系统离心压缩机变工况主动控制提供了依据。     

Bidirectional Controlled Quantum Teleportation of Three-Qubit State by a New Entangled Eleven-Qubit State

In this paper, an improved controlled bidirectional quantum teleportation protocol of the special three-qubit state is proposed. In a little bit more detail, under the control of the third supervisor Charlie, Alice wants to send one special three-qubit entangled state to Bob, and at the meantime, Bob also wants to transmit another special three-qubit entangled state to Alice. In other words, both Alice and Bob can be the sender and receiver simultaneously. To achieve this aim, a specific eleven-qubit entangled state is shared among Alice, Bob and Charlie in advance acting as the quantum channel. Then, Alice and Bob first implement the GHZ-state measurement and Bell-state measurement respectively, and following Charlie’s single-qubit measurement. Finally, upon the foregoing measurement results, Alice and Bob can respectively implement the specific unitary operators on their local particles to recover the initial state transmitted by the other.

     

Simple and Sensitive Multi-components Detection Using Synthetic Nitrogen-doped Carbon Dots Based on Soluble Starch

Journal of Fluorescence - Although carbon dots (CDs) as fluorescent sensors have been widely exploited, multi-component detection using CDs without tedious surface modification is always a...