地板送风静压层内气流的数值模拟与送风特性实验

采用计算流体力学(CFD)技术,对地板送风静压层的空气流动进行了数值模拟,并进行了典型的实验来验证计算结果.通过对计算结果与实验结果的比较,说明对于地板送风静压层内空气流动的CFD模拟,采用0 1 m的网格划分间距、标准k ε湍流模型是合理的.实验和计算结果一致表明,对于高度为170 mm的地板送风静压层,地板送风口的速度和送风量分布受到入口射流的影响,处于不同位置的地板送风口,其速度分布不同,有的均匀,有的速度值相差10倍.由数值模拟的地板送风静压层内空气流动特征,可展示和分析地板送风静压层的以上送风特性.     

回转起重机载荷摆动建模误差及不确定性定量分析

时变的非线性动力学特性和操作环境的不确定性是阻碍起重机自动化的主要因素.本文对回转起重机载荷摆动模型线性化过程中存在的误差进行了定量分析,定量描述了动力学参数对载荷摆动的最大幅值和频率的影响规律,揭示了不确定操作环境的作用规律,从而更精确描述起重机在同时做变幅、回转和起升运动工况下的系统动力学特性,为实现起重机操作自动化提供了理论依据.     

SPM的数学基础及其在脑功能成像研究中的应用

探讨SPM的数学基础,给出了SPM中利用一般线性模型(General LinearModel,GLM)构建统计参数图的方法;为了适应处理功能磁共振成像(functionalMagnetic Resonance Imaging,fMR I)数据的需要,对一般线性模型做了扩展,推导出扩展的GLM的检验统计量和自由度.最后将扩展的一般线性模型应用于一个具体的fMR I实验,说明了方法的有效性.     

铁路轨道几何状态评价方法比较

为了及时掌握列车反复荷载作用下的轨道几何形位状态，各国铁路管理部门都采用了现代轨检车和计算机处理技术来监测其变化情况，并制定了相应的评价标准．在此，通过对实测数据的分析，比较不同评价方法和标准的异同点，并对我国铁路轨道几何形位的养护和评价方法提出了参考性意见．     

风洞实验中多通道测压管路系统的参数分析

为了掌握风洞实验中多通道测压管路系统的特性，基于耗散模型，分析了影响系统频率响应函数的各个参数，总结了多通道管路系统频响函数的定性规律，并指出在常用的几何尺寸范围内，影响频响函数的因素主要有PVC管的长度、内径和限制器的尺寸及位置，为设计多通道测压管路系统提供了依据．     

Observation and dydrodynamic analysis of fast-start of yellow catfish (pelteobagrus fulvidraco)

The kinematics and hydrodynamics of the escape response of yellow catfish ( Pelteobagrus fulvidraco ) is investigated.It is observed from digital high-speed camera that all the escape response of yellow catfish is a C-type fast-start, which is characterized by the C-shape of the fish body at the end of the first contraction of the lateral musculature. Based on the analysis of the mass center movement and the performance of the caudal fin, the fast-start process can be divided into two stages: in stage one the fish body rotates rapidly around its mass center and in stage two the fish begins moving straightly. Theoretically, the Weihs' model is employed to obtain the forces, moments and turning angular accelerations acting on the fish during the escape response. The results are in good agreement with the experimental observation. Furthermore, muscle strain at different locations along the body is calculated. At last, the dynamical performance of the escape response is explained.     

Atomic-scale computer simulation for early precipitation process of Ni75AlxV25-x alloy with intermediate Al composition

The microscopic phase-field approach is applied to model the early precipitation process of Ni75AlxV25-x alloy. Without any prior assumptions, this model can be used to simulate the temporal evolution of arbitrary morphologies and microstructures on atomic scale. By simulating the atomic pictures, and calculating the order parameters and volume fraction of the θ (Ni3V) and γ'(Ni3Al) ordered phases, we study Ni75AlxV25-x alloys with Al composition of 0.05, 0. 053 and 0. 055 (atom fraction). Our calculated results show that,for these alloys, θ and γ' phases precipitate at the same time; with the increase of Al content, the amount of γ' phase increases and that of θ phase decreases; the precipitation characteristic of γ' phase transforms from Non-Classical Nucleation and Growth (NCNG) to Congruent Ordering Spinodal Decomposition (CO SD) gradually; otherwise, the precipitation characteristic of θ phase transforms from Congruent Ordering Spinodal Decomposition (CO SD) to Non-Classical Nucleation and Growth (NCNG) mechanism gradually. Both θ and γ' phases have undergone the transition process of mixture precipitation mechanism characterized by both NCNG and CO SD mechanisms. No incontinuous transition of precipitation mechanism has been found.     

Computational fluid dynamics for dense gas-solid fluidized beds

Many computational fluid dynamics (CFD) models for describing the hydrodynamics of dense gas-solid flows in fluidized beds have been put forward in the past few decades. These models treat the solid phase as continuum or discrete particles, which leads to Eulerian-Eulerian or Eulerian-Lagrangian formulations, respectively. Different governing equations and closure relations essentially result from an insufficient understanding of the complex gas?particle and particle?particle interactions for gas?solid flows. The current status of these models is discussed briefly in this paper. All the approaches in the literature modify only the solid phase momentum balance equation introducing various forms of the solid phase stress tensor and the solid phase pressure drop in the Eulerian-Eulerian models. Taking them into consideration, a new model for predicting the fluid behavior of dense gas?solid flows in fluidized beds has been developed, which contains new terms in both the particle and gas phase momentum balance equations and requires only the use of an experimental drag force correlation. Several results are shown to verify the model’s reliability, which include the homogeneous fluidization of Geldart type A particles, the bubbling and jetting fluidization of Geldart type B particles in rectangular beds, and fluid dynamics in a complicated geometry for a bubbling?bed of a fast internally circulating fluidized?bed biomass gasifier.     

糖尿病血管内皮细胞功能异常及其机理

糖尿病血管病变（Diabetic vasculopathy）是糖尿病患者致残死亡的首要原因，多种因素参与了这一病理过程，其中血管内皮细胞功能异常起重要作用。随着糖尿病患者血糖升高，患者血管内皮功能受损逐渐加重，与脂代谢紊乱、胰岛素抵抗、氧化应激等多种因素相互影响。认识血管功能的异常，探索其发病机理，对有效预防糖尿病大血管病变，提高患者生存率及生存质量是十分重要的。     

对社会调查中常用态度与方法的初步分析

社会调查实际上是由调查者与被调查者双方共同完成的。调查者不是“包打听”，也不是完全的“被告知者”，真实材料的获得要建立在双方相互尊重的前提下；每一种调查方法之间是一种弥补的关系：调查者对调查对象都怀有一种自觉不自觉的价值与情感取向，深刻地影响着调查者对材料的分析。