Three-dimensional simulation using fixed coarse-grid thermal-fluid scheme and conduction heat transfer scheme in distinct element method

Three-dimensional simulation using particle-thermal-fluid coupling scheme with a mixed Lagrangian-Eulerian approach is presented and the scheme is described by extending author's previous research [Y. Shimizu, 2004. “Fluid Coupling in PFC2D and PFC3D”, numerical modeling in micromechanics via particle methods—2004, Proceeding of 2nd International PFC Conference, Balkema, 2004, pp. 281-287]. The scheme solves the continuity, Navier-Stokes (N-S) and thermal energy equations numerically in Eulerian Cartesian coordinates, then derives pressure, velocity vectors and temperature for each fixed cell by considering particle existence. On the other hand, driving forces and thermal energy from fluid are applied to the particles as external body forces and a source term in the force-displacement law and the heat transfer calculations, respectively. This paper describes the thermal scheme for both fluid and particles. Results of two- and three-dimensional simulations involving forced convective heat transfer by fluid and conduction heat transfer within particles are presented.     

Modified Indigo Method For Gaseous And Aqueous Ozone Analyses

The indigo method developed by Bader and Hoigné for aqueous ozone analysis was modified to allow for both gaseous and aqueous ozone determination. Gas or water samples were extracted with a gas-tight syringe containing a known volume of indigo reagent. The modified procedure provided a more consistent basis for gaseous and aqueous ozone determination allowing for more accurate ozone mass balance calculations. Direct gaseous ozone UV absorbance with molar absorptivity of 3,000 M^?1cm^?1 at 258 nm was used as primary standard to determine the molar absorptivity of the indigo reagent. The molar absorptivity of indigo reagent, assuming a 1:1 stoichiometric ratio for the reaction between indigo and ozone, was determined to be 23,150 ± 80 M^?1cm^?1, or approximately 16 percent higher than that of 20,000 M^?1cm^?1 suggested by Bader and Hoigné. An independently calibrated membrane-electrode ozone monitor showed good correlation with indigo method results using the molar absorptivity value determined in this study. The apparent molar absorptivity of aqueous ozone at the wavelength of 258 nm measured by the modified indigo method increased from 2,400 to 3,600 M^?1cm^?1 in the investigated ozone concentration range of 0.4 to 11.0 mg/L. This variation might have been caused by the inherent interference of unidentified ozone byproducts, which presence was supported with scanning spectra in the wavelength range of 200 to 300 nm.     

解析“自然叠加法”在建筑环境设计中的应用——以新镇区建筑环境设计为例

人与自然的关系不能仅停留在相互依赖的层面上,人类应借助自己的思想与智慧。主动的与自然和谐共处。并处理好为促进人类发展而进行的。对于自然环境局部必要的改造与利用。譬如在改造自然环境时,应尊重自然发展规律;在利用自然资源时。应考虑可持续发展等问题;在对建筑与环境的设计实践中,应找寻出可依据的自然规律,保护、尊重环境及科学、合理的利用自然。并以恰当的方式应用手设计实践,这就是文章的研究主旨。     

—Review Paper—Current State-Of-The-Art Measurements Of Ozone In The Gas Phase And In Solution

This paper is a critical review and summary of the analytical procedures currently used by operating water utilities to control ozone treatment processes, considering disinfection as well as the many oxidative applications of ozone in water treatment applications. The role of common interferences in the various methods is described.

In operating U S., Canadian, European, and Japanese water treatment plants currently employing ozone as a primary disinfectant, ozone nearly always is followed by the addition of small quantities of chlorine, chlorine dioxide, or chloramine to provide the residual in the distribution system and to act as a secondary disinfectant. Clearly, the analytical procedures used must distinguish between the various species. This review critically presents these various factors and their implication with respect to “true values” of ozone determined under widely varying conditions.     

Modeling of photocatalytic oxidation of VOCs in a packed bed reactor under continuous and discontinuous illuminations

In this paper, a mathematical model is presented to describe the photocatalytic degradation of VOCs in a packed bed reactor. Here, the adsorption of VOCs on the wall of the reactor is taken into account and the diffusion of VOCs in the axial direction is neglected. First-order kinetics is used to describe the photocatalytic oxidation of VOCs. The analytical solution of the present model is obtained by traveling wave method. The solution shows that the reactor performance is totally dependent on the inlet concentration of VOCs when the time is large enough. The present model is validated through the experimental result of the photocatalytic oxidation of trichloroethylene in a packed bed and the predicted results accord well with the experimental data. The influence of flow rate and inlet concentration on the performance of the reactor is discussed in detail. High flow rate offers high reaction rate and low conversion efficiency. The different inlet conditions and different reaction patterns are also investigated. The model would be useful to estimate the rate constant and help to the design of the reactor.     

烧结生产线电气故障处理方法探讨

根据烧结生产线上电气故障发生的不同地方和不同类型,探讨运用不同的故障处理方法,以提高及时发现和迅速排除生产线上电气故障效率。     

基于正交试验设计的岩坡力学参数反演

对某岩坡Ⅲ区现场勘察后认为,该区为断层破碎带,属碎裂结构,岩体分级为Ⅳ级.由于地质情况复杂、岩体破碎以及边坡开挖引起的应力释放等原因,致使边坡岩体加固的力学参数用常规方法较难确定.运用正交试验设计的方法借助有限差分程序FLAC进行分析,以安全系数作为评价指标,模拟各参数不同水平的各种组合,对影响边坡稳定性的各因素进行了敏感性分析,并对边坡力学参数进行了反演,得出较为合理的力学参数,为边坡治理提供依据.     

多重网格法在地球物理正反演应用研究中的进展

现阶段地球物理三维勘探面临越来越复杂的问题,其要求更精细的三维网格剖分,现有的一些方法随着网格节点的增加其收敛速度相应减慢。对于应用中更复杂实际模型、更细密网格剖分以及更快收敛速度要求,难于有进一步提高。要有所突破,需借助计算数学最新进展,引入新的高效算法。多重网格法是近二十年迅速发展的一种求解微分方程近乎最优的新算法。本文首先简单介绍了多重网格法基本原理和运算格式,着重介绍了当前国内外多重网格法在地球物理正反演中的应用成果和发展现状。此外,对多重网格法在地球物理正反演中的应用前景及发展趋势进行了展望。     

Java 反射技术浅谈

反射是指程序可以访问、检测和修改它本身状态或行为的一种能力。通过反射,Java程序可以加载一个运行时才得知名称的class,得到其完整内部信息,并创建其对象,或对其属性进行设值,或调用其方法。反射是提高Java程序的灵活性和可扩展性至关重要的技术,它使得Java软件系统具有自适应能力。     

开关磁阻电动机工作原理及其调速系统概述

本文首先介绍了开关磁阻电动机的工作原理及常用控制方式,有电流斩波、脉宽调制方式和角度位置控制方式,其次介绍了开关磁阻电动机调速系统的基本组成,其中对功率变换器、位置检测器、电流检测器、控制器的作用进行了简单的阐述,最后介绍了开关磁阻电动机调速系统的应用。