Homogenization of hardness distribution and distortion in high pressure gas quenching

Quenching with gases rather than oil or other liquid media has the advantages of reducing the risks concerning health and environment, while simultaneously homogenizing the quenching results and minimizing distortion due to a wide range of possible process parameter variations and the pure convective heat transfer. In this contribution, a coupled solution for increasing homogenization of quenching results within high pressure gas quenching will be presented. In the first stage, an experimental test facility was set up for flow investigations and in the second stage a numerical simulation model was generated. The numerical and experimental results of the flow through the chamber were compared for several boundary conditions. Finally, after complete verification of the simulation, the model may be used to assist in parameter variation for optimization of homogeneous high pressure gas quenching.     

钢纤维聚合物混凝土抗压本构关系

钢纤维聚合物混凝土是由聚合物混凝土基体和钢纤维共同组成的纤维增强复合材料，它的力学行为不仅依赖于聚合物混凝土基体的行为，而且与钢纤维的掺量、分散特征以及钢纤维的几何尺寸有关，本文将基于损伤力学原理研究在不同纤维掺量下的钢纤维聚合物混凝土的全程压力-应变曲线及其本构模型。     

Kinetic modelling of textural changes in ready-to-eat breakfast cereals during soaking in semi-skimmed milk

Summary Ready‐to‐eat breakfast cereals immersed in milk undergo undesirable changes in texture because of sudden moisture uptake. The textural changes are ascribable to a plasticizing effect of water, which modifies the mechanical strength of products by softening the starch/protein matrix. In this work, some textural parameters of different cereal flakes were derived from the force–displacement curves monitored during 300 s of immersion in milk. Hardness loss, deformability increment and changes in the force–displacement curve profile were calculated and plotted against soaking time. The application of a sugar coating process to a model cereal flake increased the initial product hardness and improved the preservation of the textural parameters during immersion. The Peleg model closely fitted the experimental data, with regression coefficients from 0.967 to 0.999.     

Cross-Border Migration of Hong Kong Residents Under the 'One Country, Two Systems' Policy

Hong Kong is known as a migrant city because its population was sourced from mainland China, and because there has always been outflows of people to overseas countries, especially from the mid-1980s to mid-1990s. Emigration to mainland China has become a significant recent trend. This article discusses this phenomenon in the theoretical contexts of migration and trans-border residential development. It contends that the trend will intensify more quickly than other cross-border movements because the two systems are separated by a political border within one country, and because there are common cultural ties and rapid economic integration.     

Adaptive control in a heating vessel: A comparative study

This paper presents experimental results obtained in temperature adaptive control of a heating vessel. A non-linear model of the process showed that the feed flow rate causes severe variations in time constant and process gain. An extended horizon self-tuning controller and two different model reference adaptive controllers were tested. The influence of design parameters on control performance for each algorithm was assessed. The control system was disturbed with load and setpoint changes.     

Basic concept and decentralized autonomous control of super‐distributed energy systems

New small‐scale dispersed generation systems, such as fuel cells and micro gas turbines, have made remarkable advances lately and they will be applied practically in the near future. Although a large number of researches on the introduction of small‐scale dispersed generation systems have been carried out, only a small number of small‐scale dispersed generation systems are considered in these researches. Therefore, little is known about problems to be solved when a large number of small‐scale dispersed generation systems are introduced into electric power systems. This paper deals with a super‐distributed energy system that consists of a great number of dispersed generation systems such as fuel cells, micro gas turbines, and so on. The behavior of a customer with a dispersed generation system is simulated as the Ising model in statistical mechanics. The necessity of a distribution network in super‐distributed energy systems is discussed based on the Ising model. The feasibility of decentralized autonomous control using vicinity information is also investigated on the basis of stability analysis of the Hopfield neural network model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(1): 43–55, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10368     

Influence of Drying Conditions on Ascorbic Acid during Convective Drying of Whole Persimmons

Degradation kinetics of food constituents may be related to the matrix molecular mobility by glass transition temperature. Our objective was to test this approach to describe ascorbic acid degradation during drying of persimmons in an automatically controlled tray dryer with temperatures (40 to 70°C) and air velocities (0.8 to 2.0 m/s) varying according a second order central composite design. The Williams-Landel-Ferry model was satisfactorily adjusted to degradation curves for both control strategies adopted—constant air temperature and temperature fixed inside the fruit. Degradation rates were higher at higher drying temperatures, independent of the necessary time to attain the desired moisture content.     

Mathematical modelling of the alcoholic fermentation of glucose by Zymomonas mobilis mobilis

The kinetics of alcoholic fermentation of a strain of Zymomonas mobilis, isolated from sugarcane juice, has been studied with the objective of determining the constansts of a non-structured mathematical model that represents the fermentation process. Assays in batch and in continuous culture have been carried out with different initial concentrations of glucose. The final concentrations of glucose, ethanol and biomass were determined. The following kinetic parameters were obtained: μ_max, 0·5 h^?1; K_s, 4·64 g dm^?3; P_max, 106 g dm^?3; Y_x/s, 0·0265 g g^?1; m, 1·4 g g^?1 h^?1; α, 17·38 g g^?1; β, 0·69 g g^?1 h^?1.     

深圳福田河污染治理资源优化配置

根据不同河段的水域功能将污染严重的福田河自上而下划分为三个水污染控制单元，针对每个单元的不同环境目标和污染负荷预测得到相应的污染净化率，依此建立资源优化配置模型，由该模型获得优化决策，以期合理利用环境容量，确定最小净化费用，兴修必要的治理设施，从而保证在经济高速发展的同时，有效地控制福田河的污染问题。     

Biophysical Model of Larval Yellow Perch Advection and Settlement in Lake Michigan

Potential for large-scale physical transport processes to affect recruitment of Lake Michigan yellow perch (Perca flavescens) was studied by examining the variation in larval distribution, growth rate, and settlement during June–August 1998–2003 using a 3D particle transport model linked with an individual-based bioenergetics growth model. In all years, virtual larvae were released nearshore in southwestern Lake Michigan, a known and important spawning region for yellow perch. For any given year, the same circulation pattern and water temperature either promoted or reduced yellow perch settlement depending on the consumption rates and settlement size chosen in the growth model. Increased consumption increased the number of settled larvae and expanded the total area where larvae settled, whereas increased settlement size reduced the number of settled larvae and reduced the overall settlement area. Interannual variability in circulation patterns and water temperature also resulted in contrasting larval settlement rates, settlement locations, and size of settlement areas between years. Model predictions were most consistent with field observations of age-0 yellow perch from Illinois and Michigan waters when settlement was assumed to occur at 50 mm. Moreover, our model suggests that larvae originating from southwestern Lake Michigan can recruit anywhere within the southern basin and even in the northern basin. Future model improvement will require information on the relative contribution of various sectors to the larval pool, their distribution with reference to the hydrodynamic landscape, the feeding and growth of yellow perch during their pelagic phase, and the size at transition to demersal stage.