Design of a robust estimator for nonlinear kinetic modelling

A biased estimator for nonlinear kinetic modelling is studied. The proposed estimator contains two easily tuned parameters that enable the estimator to possess robustness in dealing with the problem of a nearly singular design matrix. The robustness of the estimator is discussed in detail, and the asymptotic normality of the estimator is proved concisely but rigorously. The regularity conditions imposed to obtain the results are fairly weak in engineering applications. Three examples presented demonstrate that the estimator is significantly better than the least-squares (LS) estimator and the ridge estimator in both estimate accuracy and convergence speed     

Prediction of pH Change in Processed Acidified Turnips

The acetic acid uptake by turnips was studied during an acidification process in containers. The process was successfully described by a Fickian diffusion, using a correlation for the buffer effect. Diffusion coefficients (0.629 to 3.99 × 10^-9 m²/sec) and partition coefficients (0.8 to 1.1) were obtained by optimization of the fit between experimental and theoretical values, using the simplex method. The partition coefficient did not show an evident dependence on temperature, while diffusivity followed an Arrhenius type behavior. The relationship between acid concentration and pH was described using a cubic model with parameters independent of temperature. Results showed that the combination of these models describing the acid diffusion into the food and the buffering effects of the food allowed accurate prediction of pH evolution in the acidification process.     

BAYQIK~——高浓度二氧化硫烟气制酸创新工艺

介绍拜耳技术服务公司开发的准等温接触高浓度二氧化硫烟气制酸创新工艺BAYQIK~。详述该工艺的理论基础、反应器结构、模型建立、中间试验以及在铅冶炼烟气制酸装置中的应用。BAYQIK~工艺的特点在于采用列管式固定床反应器,传统钒催化剂装在管内,冷却介质在壳程流动。氧化过程放出的热量被连续移走,从而使催化剂始终处于可承受的最高温度以下,即使反应器进气φ(SO_2)超过50%。BAYQIK~工艺可提供各种经济和工艺优点,包括可降低投资与操作成本,对于新建装置和扩能改造项目同样适用。     

GREEN UMBU (SPONDIAS TUBEROSA ARR. CAM.) PRESERVE: PHYSICAL, CHEMICAL AND MICROBIOLOGICAL CHANGES DURING STORAGE

A preserve made from “umbu” in the green state of maturity represents an alternative to avoid losses of the fruit in the mature stage. A factorial experimental design was used to evaluate the effects of formulation, packaging and storage time (0, 45 and 90 days) on the physicochemical, chemical, physical and microbiological characteristics of the preserve during storage under ambient conditions (33C/88% relative humidity). The results showed that the products were microbiologically stable, but that degradation of soluble pectin, reducing sugars and total soluble solids occurred, especially in the cellophane packaging, and this resulted in textural and color changes in the products. The results suggested the incorporation of pectin and glucose syrup and the use of a polypropylene packaging as being the most adequate method of producing and conserving preserves made from this pulp.     

TEXTURAL CHANGES IN VEGETABLES DURING THERMAL PROCESSING. II. EFFECTS of ACIDIFICATION and SELECTED PRETREATMENTS ON TEXTURE of TURNIPS

The effect of different preprocessing treatments on the softening of vegetable tissues during acidification of turnips at different temperatures was studied. Texture was characterized by the maximum load force in a puncture test. the different preprocessing treatments considered were blanching alone and coupled with vacuum infusion, freezing/thawing and calcium chloride addition. Samples were acidified at different constant temperatures: 20, 50, 70 and 90C. Results were obtained by comparing the softening occurring for all samples and for non-preprocessed turnips. It was found that for low temperature processing the final result was mainly due to the effect of the preprocessing itself on the turnip texture while for high temperature processing the effect of the preprocessing on the tissues sensitivity to the processing was more important. Blanching alone caused greater softening when processing at 70C but lead to a firmer product when coupled with calcium chloride addition or vacuum infusion for processing at 70 and 90C.     

FUNCTIONAL CHARACTERISTICS OF MUSTARD MUCILAGE

Mucilage found in hulls of yellow mustard seed was investigated. The isolated mucilage was a cold water-swellable hydrocolloid of low to medium viscosity and exhibited thixotropic properties. Viscosity increased with addition of alkali or acid. Mucilage produced synergistic increases in viscosity when combined with guar, locust bean, or carboxymethylcellulose. Solutions were opaque, bland tasting and slightly acidic. Solutions showed stability to acidity down to pH 3.5 and also to cooking and cooling cycles. The mucilage lowered the surface tension of water and the interfacial tensions of oil and water emulsions. Emulsification was achieved in model salad dressing formulations. The mucilage exhibited excellent suspending properties.