NEIGHBORHOOD APPROACHES TO URBAN CAPACITY BUILDING

The authors argue that the solution of urban problems requires resources and powers far beyond those available to most local governments. Only through partnerships of all relevant actors—public officials, businessmen and neighborhood residents—can such issues be dealt with. Yet, partnerships are neither simple nor inevitable. They require hard work and usually the development of the capacities of all involved. Such capacity building for partnerships is on three levels: the development of the individual capacity to play partnership roles; the creation of interactive partnerships operating as local problem solvers; and the fostering of inter-partnership networks. Neighborhoods are seen as the building blocks of cities, serving as a locality of scale upon which the citizen can base his concerns and actions and within which partnerships can operate effectively. Specific recommendations are made, utilizing this policy context to build capacity for partnerships at the neighborhood level, particularly with regard to the Intergovernmental Personnel Act.     

NONSPECIFICITY IN Rn

Open problems posed by Klir and Wierman (1998) for a nonspecificity measure are solved; the measure is proven additive, and its extension to nonconvex sets given. Several different proofs of additivity are given, to suggest certain techniques of wider applicability in system problems and to motivate further research possibihties. A study is initiated to refine nonspecificity separately to each dimension k≤n for the bodies residing in Rⁿ.     

The control of radiation resistance in space solar cells

Solar cells, powering satellites and other space vehicles, can suffer substantial degradation in performance by electron and proton irradiation experienced in orbit. These effects are first described, and the behaviour of silicon solar cells compared with cells of gallium arsenide and indium phosphide, and the more recent thin film type cells. In particular, the paper will discuss the phenomenon of ‘photon degradation’ in silicon cells, and recent progress in understanding the defect mechanisms responsible for this effect occurring after illumination of irradiated cells. Strategies for improving the radiation resistance of silicon solar cells, including the use of ‘defect gettering’ will be discussed, while the effects of annealing radiation damage will be outlined. Finally, the paper will seek to identify areas where an improved understanding of defect behaviour is necessary to produce further improvements in performance. In particular, it highlights the need for fundamental studies of advanced solar cell structures and materials, including CIS cells, where significant improvement in radiation tolerance has been found.     

Naringinase Immobilization in Packaging Films for Reducing Naringin Concentration in Grapefruit Juice

Naringin, a bitter compound in citrus, may be converted to a nonbitter form by enzymic hydrolysis. Our objective was to determine the feasibility of immobilizing naringinase in a food contact approved packaging film. Naringinase from Penicillium sp. was immobilized in cellulose acetate films with up to 23% efficiency at 7°C. Kinetic studies showed that the free enzyme had an optimum pH=3.5 and the immobilized enzyme pH=4.0. Activation energy decreased upon immobilization (from 14.2 to 11.0 Kcal/mol), thus providing an increased catalytic efficiency for immobilized naringinase. The Michaelis constant for immobilized naringinase (K_m=2.1 mM) was lower than for free enzyme (K_mm=3.6 mM). Keeping films under dry storage for 1 mo at room temperature did not cause decreased enzyme activity. A film area/volume ratio (cm²/mL of 10° Brix grapefruit juice) of 7.2 hydrolyzed 60% of the naringin in 15 days at 7°C.     

Prediction Equations for Gases in Flexible Modified-Atmosphere Packages of Respiring Produce are Different Than Those for Rigid Packages

Total pressure generally decreases in a sealed rigid package containing respiring produce, whereas total pressure is essentially constant and free volume decreases in a flexible package. We found that predicted O₂, CO₂, and N₂ partial pressures were different for similarly designed (same surface area, thickness, film permeabilities and produce mass) flexible and rigid packages at “quasi steady state” and steady state, respectively. Predicted O₂ and CO₂ partial pressures were slightly higher in a flexible package than in a rigid package and were a function of the film permeability ratio of N₂ to O₂ and of CO₂ to O₂. They also related to the ratio of product CO₂ production rate to O₂ uptake rate, target steady-state O₂ partial pressure, and respiration characteristics. Differences were slight for films such as low-density polyethylene.     

Control of the Properties of Glazes by the Aid of Eutectics

The alkaline earth-boric oxide-silica systems are especially important in the compounding of ceramic glazes and bodies because they enable the introduction of B₂O₃ in an insoluble form. Published equilibrium eutectics and other low-temperature invariant points were investigated regarding temperatures and rates of deformation. Most of these compositions were found to be soluble in acid, alkaline, and phosphate solutions; tests in distilled water at 195°F. for 5 days therefore were chosen as the means of selecting the compositions which would be practical for use in the development of ceramic glazes. The systems BaO-B₂O₃-SiO₂, CaO-B₂O₃-SiO₂, and SrO-B₂O₃-SiO₂ were studied first separately; the insoluble composition highest in B₂O₃ in each system was chosen for the triaxial study of the system alkaline earth-boric oxide-silica as a source of B₂O₃ in glazes and perhaps as a B₂O₃-bearing frit in ceramic bodies. Each of these insoluble glasses was also studied for the effect of limited change in composition on softening temperature and rate of deformation.     

ANALYSIS OF GASES DISSOLVED IN GLASS AND GASES PRESENT IN SEEDS*

A method of analysis for gases dissolved in glass has been developed which gives more reproducible results than those previously reported. The problem of the volatilization of alkali from the sample during the course of analysis appears to have been satisfactorily solved through the use of an auxiliary furnace. A number of commercial glasses have been analyzed for dissolved gases. Water vapor, sulfur dioxide, and oxygen are the principal gases found in flint glass. Water vapor seems to be the principal constituent of the gases found in amber glass. A method for the analysis of gases present in seeds in glass has been developed which gives fairly satisfactory quantitative results on samples containing more than 1 cu. mm. of gas. The results obtained on samples containing less than 1 cu. mm. of gas are qualitative only. The procedure consists (1) in the determination of the temperatures at which gases present in the seeds undergo a change of state and (2) in the microchemical analysis of these same gases. Seeds have been found that contained entrapped air, sulfur dioxide, and also carbon dioxide. Some seeds, especially those in amber glass, appear to be vacuum seeds, and these frequently contain a deposit on the inside which has been identified as a sulfite or a sulfate.     

SEGMENTED SECONDARY LINEAR RELUCTANCE MOTOR: ANALYTICAL AND EXPERIMENTAL RESULTS

ABSTRACT

The segmented secondary linear reluctance motor is analyzed using a permeance function approach. The basic assumptions are iron linearity and current excitation. The resulting analytical equations are implemented for numerical computation. The numerical results are compared with experimental results which are obtained from a 2 pole, 37 m/s laboratory model linear reluctance motor.     

Modelling planting configuration and canopy architecture effects on diurnal light absorption changes in cotton

Abstract

A simplified model that accounts for diurnal solar zenith and azimuth angle illumination changes and plant geometry effects on photosynthetically active radiation (PAR) was developed, h was tested using diurnal absorbed PAR (APAR) measurements acquired for cotton (Gossvpium hirsuium L.) grown at Weslaco, Texas, during the 1984 and 1986 growing seasons. Diurnal canopy reflectance and transmittance measurements were automatically collected at 3-minute intervals from about 9.00 to 14.50 local standard time (LST) using radiometers mounted 3·7m above the soil surface and PAR light bar sensors located beneath the crop canopy perpendicular to the crop rows. Plant growth measurements estimated by the model were significantly correlated with observed measurements during crop development. Model-estimated heliotropic leaf elevation trends agreed with published results for cotton canopies. APAR, relative to incident PAR, was generally lower for east-west rows than for north-south rows during crop development. The APAR response of cotton canopies for both east-west and north-south rows were found to be essentially flat when solar azimuth was between 90° and 270° so one observation close to noon would probably be representative of the diurnal APAR measurements.