NUMERICAL STUDIES OF THE THERMAL DESIGN SENSITIVITY CALCULATION FOR A REACTION-DIFFUSION SYSTEM WITH DISCONTINUOUS DERIVATIVES

The aim of this study is to find a reliable numerical algorithm to calculate thermal design sensitivities of a transient problem with discontinuous derivatives. The thermal system of interest is a transient heat conduction problem related to the curing process of a composite laminate. A logical function which can smoothly approximate the discontinuity is introduced to modify the system equation. Two commonly used methods, the adjoint variable method and the direct differentiation method, are then applied to find the design derivatives of the modified system. The comparisons of numerical results obtained by these two methods demonstrate that the direct differentiation method is a better choice to be used in calculating thermal design sensitivity.     

遥感图像配准中的块效应模拟

提出和实现了一种随机遥感图像模拟新方法,该方法集成了PROSAIL模型、随机地物类别生成和尺度扩展机制,实现了随机点图像模拟和随机块图像模拟.实验中定量模拟了HJ-1 CCD传感器近红外成像光谱波段图像及具有不同平移、旋转、尺度变化影响的实验图像.利用模拟图像研究了平移、旋转、尺度变化等多种因素对近红外图像配准的影响,通过模拟地物随机分布及尺度变化的随机块图像分析了块效应在图像配准中的作用,并试验将随机模拟图像用于对图像配准算法进行适宜性分析.模拟实验结果表明图像块效应对图像配准处理具有重要影响.     

ENZYMES IMMOBILIZED ON FORMED-IN-PLACE MEMBRANES FOR FOOD PROCESSING: PROCEDURES and PROPERTIES

The formation and properties of Formed-In-Place (FIP) membranes upon which enzymes had been immobilized were investigated to examine the potential of these reactive membranes in food processing applications. Enzymes were immobilized on two types of FIP membranes and their activities in appropriate fluids investigated. Flux was increased in the microfiltration of pectin solutions by immobilizing pectinase on titanium dioxide microfiltration membranes. A flux increase of 15% was obtained without permeate recycle and 112% with permeate recycle using a 0.1% solution of citrus pectin. Glucose production from dextrin was performed using glucoamylase (GA) immobilized on a zirconium hydrous oxide-polyacrylate nanofiltration membrane. Optimum activity occurred at pH 4.0 and 50C for the immobilized GA. the dextrose equivalent (DE) value of the membrane permeate was approximately ten times higher than the product obtained with free GA during the same time interval.     

Formation of Volatile Compounds in Sugar-Phenylalanine and Ascorbic Acid-Phenylalanine Model Systems during Heat Treatment

Formation of volatile compounds during heating at 99°C for 1.8 min of model systems constituted by diluted solutions of sugars (glucose or fructose) or ascorbic acid and phenylalanine was investigated. The results obtained show that furfural is the only one furan derivative formed under these conditions and quantitative data indicate that ascorbic acid is its main precursor. The other derivatives found in tomato juice heated under the same conditions (5-méthyl furfural, 2-acetylfuran, 5-méthyl-2-acetylfuran, furfuryl alcohol) are not formed. The formation of phenylacetaldehyde can be explained by Strecker degradation of phenylalanine rather than direct thermolysis of his product. Aromatic hydrocarbons, found in the three model systems studied, are certainly formed by thermal degradation of pheny alanine.     

EFFECT OF VACUUM-PACKING AND STORAGE IN NITROGEN AND CARBON DIOXIDE ATMOSPHERES ON THE QUALITY OF FRESH RABBIT MEAT

In order to evaluate the effects of vacuum-packing and storage in CO₂ (100%), and N₂ (100%) atmospheres on the quality of fresh rabbit meat, rabbit carcasses were stored in the dark at 0°C and 3°C for 50 days. Every 5 days, psychrotrophic bacteria and lactobacilli counts were obtained, and pH, water retention, texture, and color measured. Storage in CO₂ maintained good microbiological quality, but caused a decrease in water retention capacity, which led to discoloration and toughening of the meat. On the other hand, storage under N₂ atmosphere improved water retention and consequently organoleptic properties, but this advantage was nullified by lower microbiological quality. Due to the loss of water from the tissues, vacuum-packing resulted in changes of the organoleptic quality of the meat, similar to those observed by storage in a CO₂ atmosphere. At refrigerated temperatures, a variation of 3 °C had a larger effect on bacteriological counts and tenderness than the outer quality parameters. Thus, a mixture of gases (CO₂ and N₂) having both the bacteriostatic properties of one and the organoleptic advantages of the other might be a better choice to optimize the shelf-life of rabbit meat.     

Sensory changes in liquid milk during storage and the effect on consumer acceptance

The acceptance of dairy products by consumers is generally determined by the product's sensory characteristics. These characteristics are a result of various changes in the product and the surrounding environment. The purpose of this paper is to report on a detailed sensory and consumer investigation of the changes in liquid skimmed milk held over an eight day period at three different storage temperatures: 1°C, 5°C and 10°C. Results of an objective sensory profile and subsequent data analysis revealed that sensory changes in milk could be described and quantified, clearly indicating the product's shelf-life profile. Product acceptability as perceived by consumers was undertaken on a subset of samples, illustrating the points at which consumers noticed significant changes. Overall, as the samples went through their shelf-life at the higher temperature they became less acceptable. The final part of the experiment used statistical modelling procedures to interpret and understand the data. As expected, it was shown that products became more stale during storage, and that temperature of storage affected the rate of staling, this being most marked at the higher temperature. Staleness was related to the attributes vegetable, sour, cardboard, chalky and mouthcoating.     

MINORITY POLITICAL REPRESENTATION AND LOCAL ECONOMIC DEVELOPMENT POLICY

ABSTRACT: This article examines the relationship between black and Hispanic political representation in local government and the economic development policy approaches pursued by city administrations. It asks whether the administrations of black and Hispanic mayors are more likely than other administrations to follow policy approaches that address the interests of minority residents. In each aspect of development policy examined, the results indicate that administrations of minority mayors are no more likely than other administrations to promote the interests of minority constituents.     

Exact pole assignment by output feedback Part 3

This part concludes a series of three papers concerning controllable and observable linear time-invariant multivariable control systems in which the number of outputs plus the number of inputs exceeds the number of states. Following from the second paper (Fletcher 1987) it remains to consider the assignment by real output feedback of a set of distinct eigenvalues consisting of a mixture of real numbers and complex conjugate pairs of non-real numbers. We examine the possibility that in the algorithm described in the first paper (Fletcher and Magni 1987) all the real eigenvalues can be assigned before any of the complex conjugate pairs. If this is possible then the argument of Fletcher (1987) can be used to complete the assignment. It is only from the failure of this possibility that the pathological cases detailed in the first paper can arise.     

The effects of cosmetics on person perception

The study reported here forms part of an investigation of what psychological benefits, if any, exist for the user of cosmetics. A central theme in the work on physical attractiveness is that if one is physically attractive one is assumed to have a more ideal personality than someone of lesser attractiveness. If cosmetics really do make people look more physically attractive, then with the use of cosmetics others should perceive people more favourably in terms of personality characteristics. This study, therefore, attempted to find out whether cosmetics really do improve appearance ratings (by males and females) and in result improve ratings of personality. Colour photographs of four female stimulus persons of average physical attractiveness in each of four modes (neither make-up nor hair care; make-up but no hair care; no make-up but hair care; both make-up and hair care) were evaluated by a judge panel of sixteen males and sixteen females. The amount, extent and style of use of facial make-up and hair care was no more than would be in everyday use. Each judge saw one stimulus person in each mode but no stimulus person in more than one mode in a counter-balanced design, using 7-point rating scales of six appearance and fourteen personality dimensions. Two hypotheses were confirmed:

• 1 The use of cosmetics (facial make-up and hair care) leads to more favourable appearance ratings by others (both males and females). For make-up there were more favourable ratings on all of the six appearance scales, and for hair care there were more favourable ratings on four of the six appearance scales.
• 2 The use of cosmetics leads to more favourable ratings of personality as perceived by others (both males and females). Facial make-up enhanced ratings on eight of the fourteen personality dimensions tested and hair treatment led to more favourable ratings on ten of the scales.

It is not certain from this study whether persons using cosmetics are rated more favourably than without cosmetics because they are seen as more physically attractive and in result acquire more favourable ratings for attributes which are associated with being physically attractive or whether there is a direct effect on perceived personality, independent of enhancement of physical attractiveness, or both. Either explanation is possible, though there is some support for the idea that the use of cosmetics (or at least hair care) may have a direct effect on perceived personality. If this were so, it would suggest the existence of a separate positive cosmetic stereotype which carries its own concept ‘what has been cared for is good’. This stereotype would form an extension of the ‘what is beautiful is good’ stereotype for physical attractiveness. Otherwise, and as a result of the work reported here, the latter might become ‘what has been made beautiful is good’, when cosmetics are used.