IDEAS based synthesis of minimum volume reactor networks featuring residence time density/distribution models

This work addresses for the first time, the synthesis of globally minimum volume reactor networks, featuring segregated flow reactors (SFR) and/or maximum mixedness reactors (MMR), with the same normalized residence time density (NRTd) function. Global optimality is ascertained by demonstrating that the input–output information maps of SFR and MMR with general RTd/RTD models satisfy all properties required for the application of the infinite dimensional state-space (IDEAS) approach to the RTd/RTD reactor network synthesis problem. The resulting IDEAS formulation is shown to possess a number of novel properties, which can be used to facilitate its solution. The power of the proposed methodology is demonstrated on three case studies featuring segregated laminar flow reactors (SLFR) in which the Trambouze reaction scheme is carried out. In one of the case studies, the identified reactor network is shown to have volume that is as low as half the volume of a single reactor.     

FVM based numerical study on the effect of solder bump arrangement on capillary driven flip chip underfill process

In this paper, the finite volume method (FVM) based numerical simulation is used for the flow visualization of capillary driven underfill process for different solder bump arrangements of flip chip packages is presented. Three different 3D flip chip package models are developed and simulated using computational fluid dynamic (CFD) code, FLUENT 6.3. Capillary action and cross viscosity model are taken into account in the simulation. One-line dispensing method is applied in the analysis and the volume of fluid (VOF) technique is used to track the flow front. The effect of solder balls arrangement on flow behavior and filling time is studied and the solder balls arrangement is found to affect the flow behavior and filling time. The flow patterns of simulation are observed for three flip chip packages and compared. The ability of the proposed model and FLUENT in handling flip chip underfill problems is proved to be excellent.     

Constitutive modeling for the dynamic recrystallization evolution of AZ80 magnesium alloy based on stress-strain data

In order to improve the understanding of the dynamic recrystallization (DRX) behaviors of as-cast AZ80 magnesium alloy, a series of isothermal upsetting experiments with height reduction 60% were performed at the temperatures of 523 K, 573 K, 623 K and 673 K, and the strain rates of 0.01 s⁻¹, 0.1 s⁻¹, 1 s⁻¹ and 10 s⁻¹ on a Gleeble 1500 thermo-mechanical simulator. Dependence of the flow stress on temperature and strain rate is described by means of the conventional hyperbolic sine equation. By regression analysis, the activation energy of DRX in the whole range of deformation temperature was determined to be Q = 215.82 kJ mol⁻¹. Based on dσ/d? versus σ curves and their processing results, the ?ow stress curves for AZ80 magnesium alloy were evaluated that they have some characteristic points including the critical strain for DRX initiation (?_c), the strain for peak stress (?_p), and the strain for maximum softening rate (?*), which means that the evolution of DRX can be expressed by the process variables. In order to characterize the evolution of DRX volume fraction, the modified Avrami type equation including ?_c and ?* as a function of the dimensionless parameter controlling the stored energy, Z/A, was evaluated and the effect of deformation conditions was described in detail. Finally, the theoretical prediction on the relationships between the DRX volume fractions and the deformation conditions were validated by the microstructure graphs.     

Unsaturated elasto-plastic constitutive equations for compacted kaolin under consolidated drained and shearing-infiltration conditions

Transient process of water flow changes the equilibrium conditions of an unsaturated soil, resulting in volume change of a soil. The volume change alters the hydraulic properties of the soil and thus influences the transient process of water flow through the soil. Therefore, the interactive processes between stress-strain behavior and pore-water pressure are the primary processes affecting the mechanical behavior of unsaturated soils. This paper presents coupled elasto-plastic constitutive equations for unsaturated compacted kaolin under consolidated drained and shearing-infiltration conditions. The study focused on the development of the suction increase (SI) yield curve that incorporates changes in matric suction during transient processes. In addition, the relationship of change in specific water volume with respect to net mean stress and matric suction was also proposed by incorporating the hysteresis of soil-water characteristic curve. The simulated results by the proposed constitutive model were compared with those obtained from isotropically consolidated drained tests and shearing infiltration tests of compacted kaolin to verify the proposed model. The simulated results are in close agreement with the experimental results.     

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Abstract

This work proposes a hypothesis for the interpretation of shrinkage anisotropy during sintering of an Fe–Cu–C alloy based on the effect of the structural modifications of the powder, due to the prior compaction, on the mass transport phenomena. Dislocations are introduced by cold compaction in the contact regions between particles, with different densities along the compaction direction and the transversal one. Therefore, the mass transport by volume diffusion is strongly activated in both directions, and a prevailing effect in the compaction direction is shown. The volume diffusion coefficients derived from the kinetic model correspond to the dislocation pipe diffusion mechanism.     

铕原子标记技术检验实验室移液器容量误差方法

建立铕原子标记技术对实验室移液器容量的比对与校准,能实现对小容量移液器容量准确度与精密度的有效监控。采用时间分辨荧光检测技术,检验移液器容量的误差来源。时间分辨荧光法检测批内重变性误差在0.17%~7.8%之间。铕标记法与蒸馏水称重法对移液器容量测定的比对试验,相对误差-3.9%~0.62%。时间分辨荧光进行移液器容量比对与误差评估,方法灵敏、精确、简便,可适用于临床实验室移液器容量的误差识别及常规比对。     

Quality Performance,Proximate Composition and Sensory Evaluation of Developed Flavoured Instant Popcorn

Popcorn is a world famous snack food with significant commercial demand. Its market has been continuously growing in Sri Lanka. At the same time, different variety of instant popcorn products should be tested for sensory attributes, proximate composition and quality performance. The flavoured instant products were developed by adding 15%, 25% and 35% butter and butter oil as separately and 0.5 g, 1.0 g and 1.5 g salt respectively for 20 g of raw popcorn grains. 35% butter incorporated popcorn had significantly higher median score for appearance, taste and overall acceptability. There was no any effect of level of salt added. Proximate composition was determined for raw seed, raw popped flakes and flavoured popped flakes. Butter flavoured popped corn flakes were showed higher level for crude fat content and mineral content while lowest content for carbohydrate 16.71%, 2.4% and 64.2% respectively. Kernels were popped using a microwave oven and visually sorted into three different polymorphisms depending on whether the appendages were expanded unilaterally, bilaterally, or multilaterally. The expansion volume before sorting was comparatively lower and it was 10-11cm3/g. When popped, 37.37%, 14.02%, and 33.57% of kernels were expanded unilaterally, bilaterally, and multilaterally, respectively, while 14.2% of kernels remained unpopped. Expansion volumes in respect to flake weight were shown significant differences for unilaterally, bilaterally, and multilaterally expanded polymorphisms of 9.34, 8.86 and 12.29cm3/g, respectively.     

密度梯度曲线的设计和配制

本文从理论上证明得出、当重、轻混合液的体积相同时,并且重混合液的流速为轻混合液的流速的二倍时,从重混合液中流出的比重就是密度管高度的线性函数。     

Predictive Model for the Water Retention Curve of Deformable Clayey Soils

Tests for determining the water retention curve (WRC) can be time-consuming and tedious, especially with deformable soils for which volume change and water content have to be simultaneously monitored. In some cases, predictive models can become a practical alternative to obtain an estimate of the WRC. However, very few models are available to predict the WRC of deformable materials under increasing suction. In this paper, the modified Kovács (MK) model, developed initially for incompressible soils, is extended to describe and, in some cases, predict the WRC of deformable clayey soils. This generalization of the MK model is performed by introducing the volumetric shrinkage curve (VSC) in its formulation. A curvilinear equation is proposed to represent the void ratio-suction function e(ψ) corresponding to the VSC. This VSC model and the extended MK model (MKd) are validated using experimental data taken from the literature. Empirical relationships are developed for predictive purposes to estimate the parameters involved, using basic geotechnical properties. Applications show a good agreement between measured and calculated WRC.     

利用硬盘卷序列号实现对VB软件注册的解决方案

在VB应用软件中通过读取用户计算机的硬盘卷序列号作为机器码，加密后生成软件注册码。由于硬盘卷序列号是唯一的，提供的软件注册码也是唯一的，用户利用该软件注册码可实现对VB应用软件的注册。本文阐述了利用硬盘卷序列号实现对VB软件注册的详细实现过程。