灰尘在风管中运动轨迹的数值模拟

对通风管道中的气固两相流动流场进行数值模拟，是研究颗粒在通风管道中的运动轨迹。计算中将气相作为连续介质，采用RSM湍流模型。并用SIMPLE算法对流场进行数值模拟；将固相作为离散体系，采用随机轨道法计算其运动轨迹。计算时，分别选用6种颗粒直径为计算工况，计算结果显示出颗粒运动轨迹，指出其与气流速度和颗粒直径相关。     

168kA新型阴极高效节能铝电解槽磁流体运动的数值模拟

建立了168 kA新型阴极铝电解槽磁流体运动的数学模型,对电解质与铝液交界面的流场、电解质的流场以及阴极铝液的流场进行了模拟,并对新型阴极电解槽阳极导杆等距电压降进行了测量。研究结果表明：新型阴极铝电解槽可隔断槽内铝液流动,降低槽内阴极铝液的流速。新型阴极铝电解槽铝液与电解质交界面的速度矢量和较普通阴极铝电解槽铝液与电解质交界面的速度矢量和低2～3倍,且极值分布更为均匀。新型阴极电解槽内铝液与电解质界面处的磁流体速度最大,然后以界面为中心线逐渐减小。     

锌电解槽内电解液流动现象的水力学和数值模拟

以云南驰宏锌锗公司的锌电解槽为基础,根据相似原理制作了相应的水模型,对其内部的流动现象进行了研究;同时,利用商业软件FLUENT对锌电解槽的内部流场进行数值模拟。结果表明:数值模拟建模时采用四边形网格得到的计算结果与水力学模拟的结果相吻合,能够较真实地反映锌电解槽的内部流场。还对不同实际工况下锌电解槽内的流场进行了研究,并提出相关建议,为进一步改善和优化电解槽结构、扩大电解槽规模提供理论依据。     

基于CFD的平行流铜电解槽槽型优化设计

以平行流铜电解槽为对象,ANSYS软件为平台,对不同进液方式下电解槽槽内流场分布进行数值模拟。结果表明,进液方式对平行流电解槽极间电解液的流动有重要影响,与下部分段进液槽型和上部交错进液槽型相比,下部交错进液槽型具有较大的极间电解液流动速度与较均匀的速度场。     

稀土钕氧化物电解槽内液-液两相流动研究

钕氧化物电解槽内金属钕在阴极表面生成后在电解质中的下沉过程属于典型的两相流动。以3 kA钕电解槽为实物原型,建立了二维非稳态液—液两相流动模型,通过数值模拟的方法得到了不同时间的流场分布和钕液浓度分布图,并对得到结果进行了分析。     

稀土电解槽电极的优化模拟

利用流体软件FLUENT,建立了稀土电解槽的阳极气泡及熔体整体流场数学模型。对电解槽的电极插入不同深度的流场进行了数值模拟,得出了电解槽的熔体整体流场分布图及在不同位置气体浓度分布曲线图。     

槽形结构对10 kA稀土电解槽流场分布的影响

采用CFD软件FLUENT,建立了三维气—液两相流动模型,对某稀土金属公司现场使用的10 kA方形和圆形两种结构的稀土钕电解槽内部流场进行数值模拟,得到了这两种不同结构电解槽中的熔盐上表面流场分布和槽内各纵切面上的流场分布。通过比较分析可知,采用圆形结构较方形结构能使得其中的熔盐具有更好的循环流动,流场分布更加均匀,并且在相邻阳极片之间圆形槽的熔盐会较方形槽熔盐具有较小流速,故对石墨阳极的冲刷腐蚀影响小,有利于减少石墨阳极的更换次数,便于保障稀土金属电解生产的稳定性,故推荐稀土电解槽优先采用圆形槽结构。     

稀土电解槽气液两相流动数值模拟

利用CFD软件,建立了稀土电解槽的阳极气泡及熔体整体流场数学模型。对稀土电解槽的阳极表面化学反应自动生成气体的流场进行了数值模拟,得出了电解槽的熔体整体流场分布图及在不同位置气体浓度分布曲线图,使之更贴近于电解槽的实际工况,为熔盐稀土电解槽的槽型优化提供依据。     

旋风子中气相流动特性及颗粒分离效率的数值研究

采用Fluent软件对轴向进口旋风子内的气相流场和颗粒分离效率进行了三维数值研究。用RNG（重整化群）κ－ε湍流模型模拟气相紊流特性。采用拉格朗日模型对固相颗粒的轨迹进行了模拟,并对固体颗粒的分离效率进行了分析。     

T型中间包湍流控制器对夹杂物去除的影响

通过水力学模拟试验和数值模拟试验,研究湍流控制器对夹杂物上浮去除的影响,并比较了有无湍流控制器时中间包内夹杂物颗粒的运动轨迹。湍流控制器使从大包注入的钢液返流到达自由表面,从而消除中间包底部流,发展表面流,有利于夹杂物的去除。其中湍流控制器+挡坝的结构对促进夹杂物去除效果最好。     

Role of platelet-activating factor in glucose uptake and utilization of different tissues

The particle transport characteristics of two ventilation configurations commonly used in hospital operating rooms (ORs), cross-flow and impinging-flow ventilation, were investigated. The computational fluid dynamics software FLUENT was used to simulate turbulent airflow with mixed convection in a three-dimensional, rectangular OR. Two OR personnel, a patient, OR spotlights, an anesthetics cart, and an operating table were represented in the room. Heat loads from the personnel, patient, and lights affected the airflow through buoyancy. Particles produced at the operation site with various sizes and initial conditions were tracked through the room. A stochastic model was used to include the random effects of turbulence on particle trajectories. Simulation results show that heat loads from the personnel, patient, and OR spotlights had an important effect on the airflow through natural convection. Particle trajectories were influenced greatly by the flow field structure, particle launch position, and turbulence in the flow, and somewhat by particle size. However, particle paths were insensitive to the launch velocity. Virtually identical trajectories were obtained for particles with launch velocities ranging from 0 to 1 m/sec in magnitude. Changes in ventilation configuration dramatically affected particle transport. The cross-flow ventilation configuration performed better, based on the criteria of removing particles from the breathing zone of room occupants. Proper flow field design and contaminant source placement can be used to control particle transport. Numerical simulations allow quick and inexpensive comparisons between room designs and provide details about airflow and contaminant transport.     

Jet Integral–Particle Tracking Hybrid Model for Single Buoyant Jets

The mixing processes of a buoyant jet discharged from a submerged single port were analyzed using a three-dimensional hybrid model. In the proposed hybrid model, the initial mixing was simulated by a jet integral method, and the advection-diffusion process was simulated using a particle tracking method. Laboratory experiments were conducted for various flow conditions in order to verify the proposed model. The simulated horizontal concentration distributions and minimum dilutions at the water surface were generally in agreement with the observations. The vertical concentration distributions for coflowing jets were well simulated by both the jet integral and the particle tracking methods of the hybrid model. Trajectories simulated by the jet integral module of the hybrid model were in agreement with the measured trajectories when the velocity ratio was low. For cases where the velocity ratio was high, the hybrid model in which the vortex-pair distribution was used gave better results than the hybrid model with only Gaussian velocity distribution.     

共格畸变影响沉淀相形貌的计算机研究

利用微观扩散方程 ,结合微观弹性力学理论 ,对二元立方模型合金的沉淀过程进行计算机模拟 ,通过取不同的应变能参数B ,研究共格畸变对沉淀相形貌的影响。研究发现 :当忽略应变能时 ,沉淀相为随机分布的等轴颗粒 ,呈各向同性特征 ,其粗化遵循奥斯瓦尔德熟化机制 :小颗粒溶解 ,大颗粒长大。当考虑应变能时 ,沉淀相为片状 ,趋于沿弹性 <0 1>“软”方向排列 ,呈各向异性特征 ,位于“软”方向上的颗粒继续长大和粗化 ,位于“软”方向外的颗粒逐渐消失 ,而对于同一行或列上的颗粒又存在小颗粒溶解、大颗粒长大现象。由模拟结果还可看出 :在共格畸变作用下 ,相分离过程显著减慢     

Community-Based Prevention of Marital Dysfunction: Multilevel Modeling of a Randomized Effectiveness Study.

This study is a cluster randomized controlled trial of the Prevention and Relationship Enhancement Program (PREP; H. J. Markman, S. M. Stanley, & S. L. Blumberg, 2001). Fifty-seven religious organizations (ROs), consisting of 217 newlywed couples, were randomly assigned to 1 of 3 intervention conditions: PREP delivered by university clinicians (U-PREP), PREP delivered by RO clergy (ROPREP), and naturally occurring (NO) marriage preparation. Self-reported relationship satisfaction, negative behavior, and positive behavior were assessed at preintervention, postintervention, and 1-year follow-up. Trajectories of relationship satisfaction showed no change over time and did not differ across conditions. Trajectories of negative behavior for RO-PREP wives showed significantly greater linear declines in comparison with NO trajectories. Trajectories of positive behavior for NO and U-PREP partners showed significant declines compared with RO-PREP trajectories. Effectiveness, transportability, and dissemination of marital distress prevention programs in community settings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evolution of Size and Chemical Composition of Copper Concentrate Particles Oxidized Under Simulated Flash Smelting Conditions

An experimental study was conducted to elucidate the evolution of size and chemical composition of La Caridad copper concentrate particles during oxidation under simulated flash smelting conditions. Input variables tested included particle size and oxygen concentration in the process gas. The response variables included the size distributions, chemical composition, and morphology of the reacted particles at seven locations along a laboratory reactor. Particles with initial size < 45 µm contained mostly chalcopyrite, they increased their mean size and decreased the amount of dust in the population during oxidation. This was explained by a reaction path involving rapid melting followed by collision and coalescence of reacting droplets during flight. Particles with sizes > 45 µm contained varying amounts of chalcopyrite and pyrite, and tended to either maintain or decrease their mean size upon oxidation. When size reduction was observed, dust was produced because of fragmentation, and the particles showed no evidence of collisions during flight. The main oxidation products detected in the particles consisted of matte, cuprospinel, and magnetite. A plot of the mean size divided by the mean size in the feed against the fraction of sulfur eliminated generalized the experimental data so far reported in the literature, and helped identify the reaction path followed by the particles.     

Physical modelling of slag-foaming phenomenon resulted from inside-origin gas formation reaction

Slag foaming is a common phenomenon in the metallurgical process that negatively influence the blast furnace when smelting some special ores such as V-Ti-magnetite. Inside-origin gas plays a leading role during this foaming phenomenon. This study performed a room-temperature simulation of slag foaming from inside-origin gas. Results showed that foaming height increased with increased the amount of inside-origin gas. Higher liquid viscosity caused lower foaming height, which was opposite to the slag-foaming regularity caused by outside-origin gas. Higher surface tension benefited the suppression of the foaming phenomenon and shortened the foaming elimination time. The effect of solid particles on the foaming phenomenon was not monotonic, i.e. the maximum foaming height initially increased and then decreased with increased number of particles. Particles with better solution wettability caused higher foam because they can easily adhere onto film, thereby enhancing elasticity and extending film life. Small particle size benefited the foam. The experimental data were in accordance with the model predictions based on the estimated bubble sizes, which proved that the model developed by Zhu and Du helped predict foaming height caused by chemical reaction.     

Trajectories of school engagement during adolescence: Implications for grades, depression, delinquency, and substance use.

Using longitudinal data from the 4-H Study of Positive Youth Development, the authors assessed 1,977 adolescents across Grades 5 to 8 to determine if there were distinctive developmental paths for behavioral and emotional school engagement; if these paths varied in relation to sex, race/ethnicity, and family socioeconomic status (SES); and whether links existed between trajectories of school engagement and grades, depression, substance use, and delinquency. Four trajectories for behavioral school engagement and four trajectories of emotional engagement were identified using a semiparametric mixture model. These trajectories were distinct with regard to initial levels of and changes in engagement, as well as to their shapes. Trajectories varied in regard to sex, SES, and race/ethnicity. Different trajectories of behavioral and emotional engagement were linked to grades, depression, delinquency, and substance use. Directions for future research and application are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal decomposition of limestone in a fluidized bed

Particles of limestone of 16 to 28 and 60 to 100 mesh sizes were decomposed in a fluidized bed. A mathematical model for the thermal decomposition was proposed comprising the thermal decomposition at the interface within particles and the related heat and mass transfer steps. It was assumed in this model that the particles are completely mixed within the fluidized bed and that gas is in upward plug flow. Fractional decomposition of limestone particles and the bed temperature during thermal decomposition calculated from this model coincide very well with the experimental results. It was further revealed that the overall reaction rate of 60 to 100 mesh size particles is virtually determined by the rate of heat transfer from the reactor wall to the fluidized bed, and that both rates of interfacial reaction and heat transfer from the wall to the bed contribute to the overall decomposition rate of 16 to 28 mesh size particles. Former Graduate Student at Kyoto University, is now with the Railway Technical Research Center, JNR, Tokyo, Japan.     

The normative development of child and adolescent problem behavior.

The aim of this study was to identify normative developmental trajectories of parent-reported problems assessed with the Child Behavior Checklist (CBCL; T. M. Achenbach, 1991) in a representative sample of 2,076 children aged 4 to 18 years from the general population. The trajectories were determined by multilevel growth curve analyses on the CBCL syndromes in a longitudinal multiple birth-cohort sample that was assessed 5 times with 2-year intervals. Most syndromes showed a linear increase or decrease with age or a curvilinear trajectory, except for thought problems. Trajectories for most syndromes differed for boys versus girls, except those for withdrawn, social problems, and thought problems. These normative developmental trajectories provide information against which developmental deviance in childhood and adolescence can be detected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fractionation and Segregation of Suspended Particles Using Acoustic and Flow Fields

The exploratory research of applying an acoustic standing wave to a sediment flow stream to fractionate and segregate particles was investigated. Using fundamental physics of particles in an acoustic field, a mathematical model was developed to calculate trajectories of deflected particles due to the application of acoustic standing waves. Then at the bench scale, the above technology was implemented by building a flow chamber with two transducers at opposite ends to generate an acoustic standing wave. The technology was evaluated using uniform size silicon dioxide and silicon carbide particle suspensions in de-ionized water. Due to the acoustic force field, SiO2 particles migrated toward the pressure nodes at half wavelength intervals at an optimum frequency of 333 kHz and 40 W power. Dark lines representing particle columns were formed after the application of the acoustic field, which was recorded in videotape. However, due to the small particle size of SiO2, particle trajectories could not be recorded, hence the slightly larger sized SiC was used to track particle trajectories. The displacements of SiC particles due to an acoustic force were compared with the mathematical model predictions. For input power level between 3.0 and 5.0 W, the experimental data were comparable to mathematical model predictions. Also, from the experimental data it was possible to develop a relationship between input power and acoustic energy in the resonance chamber. Hence based on preliminary results it can be concluded that the acoustic field can be used either to segregate or fractionate fine particles.