AN EVALUATION OF THE ALLEGHENY COUNTY NEIGHBORHOOD PRESERVATION PROGRAM

The Allegheny County Neighborhood Preservation Program has generated over five million dollars worth of housing rehabilitation in the three years in which it has been operating. This article is an evaluation of Phase 1 of the program. It compares loan recipients and non-recipients in order to determine which of the program components are the most important, which factors influence a household's investment decision, and what effect investment has on the perceptions of residents regarding the quality of both housing and the neighborhood.     

Aluminum Oxyhydroxides Formed by the Reaction of Methyl Esters with Sodium Aluminate Solution

Properties of the aluminum oxyhydroxide formed by the reaction of methyl acetate on solutions of sodium aluminate are examined. The solid has a high specific surface and gives an X-ray diffraction pattern different from those of other known oxyhydroxides. A quite different product (coarse bayerite) is obtained when esters which cannot have an enolic form are used. A possible formation mechanism of the oxyhydroxide is discussed.     

Modified Atmosphere Storage of Rockfish Flllets

A modified atmosphere (MA) of 80% CO₂ and 20% air was effective in extending shelf life of fresh rockfish fillets. Aerobic plate counts and trimethylamine levels were significantly lower (P < 0.1%) for the fillets held in MA compared to those held in air. A decline in surface pH was observed on fillets stored in MA, presumably due to the absorption of CO₂ and its hydration to carbonic acid. Oxidation-reduction potentials suggested a more aerobic environment on fillets stored in MA. There were no significant differences in weight loss between control and MA samples. Sensory evaluations indicated that fillets held under MA were of good quality for at least 13 days of storage.     

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.     

Structure and magnetic properties of Cu-Ni alloy nanoparticles prepared by rapid microwave combustion method

Cu-Ni alloy nanoparticles were prepared by a microwave combustion method with the molar ratios of Cu²⁺ to Ni²⁺ as 3:7, 4:6, 5:5, 6:4 and 7:3. The as-prepared samples were characterized by XRD, HR-SEM, EDX and VSM. XRD and EDX analyses suggest the formation of pure alloy powders. The average crystallite sizes were found to be in the range of 21.56–33.25 nm. HR-SEM images show the clustered/agglomerated particle-like morphology structure. VSM results reveal that for low Ni content (Cu₅Ni₅, Cu₆Ni₄ and Cu₇Ni₃), the system shows paramagnetic behaviors, whereas for high Ni content (Cu₃Ni₇ and Cu₄Ni₆), it becomes ferromagnetic.