An implementation perspective of applying object-oriented database technologies

As a result of improvements in information technology, more system designs and implementations require data-intensive applications. The most promising approach to solving these problems is the object-oriented database architecture. Unfortunately, object-oriented database management systems have not matured. Lack of agreements in the data models and formal foundations have created problems in using them. However, systems are being designed and developed with object-oriented philosophies even though important issues still need to be resolved. This paper examines the important issues in designing an object-oriented database prototype from three perspectives: object technologies, database technologies, and application environments. Each issue is discussed separately and illustrated with C++/Versant.     

GAMMA RADIATION DOSE RATE AND SWEET POTATO QUALITY

“Jewel” sweet potatoes were irradiated with gamma radiation and a dose-rate relationship on nutrients was investigated. The total dose was 1 kGy/h. The results indicated that generally moisture, ascorbic acid and carotenoids level were higher at high dose rates than at low dose rates. Starch and texture tended to decrease with increase in dose rate. Thiamin and riboflavin were not affected by dose rate. The effect on sugars was not clear. The levels of sugar constituents for roots irradiated at 10.40 kGy/h tended to be higher than other dose rates. Some differences were significant.     

Microbiological Changes in Fresh Market Tomatoes During Packing Operations

Preliminary studies in two fresh market tomato packing houses in the Charleston, SC area showed significant differences in microbial counts on tomatoes by packing house, sampling point in packing lines, and season. Higher total plate counts, Enterobacteriaceae counts, and mold counts were found in one packing house, probably due to a failure to maintain adequate chlorine in the wash water. Total plate and Enterobacteriaceae counts were higher on tomatoes packed in July than in November. Enterobacteriaceae and molds isolated from the tomato samples were those normally associated with soil-borne contamination. Enterobacter agglomerans, Enterobacter cloacae, and Serratia marcescens were predominant Enterobacteriaceae identified; Alternaria, Penicillium, and Cladosporium were the predominant molds isolated and identified.     

A general one-dimensional search algorithm for computing approximate solutions of some non-linear optimal control problems

Barr and Gilbert (1966, 1969 b) have presented computing algorithms for converting a brood class of optimal control problems (including minimum time, and fixed-time minimum fuel, energy and effort problems) to a sequence of optimal regulator problems, using a one dimensional search of the cost variable. These Barr and Gilbert algorithms, which use quadratic programming algorithms by the same authors (1969 a) to solve the resulting optimal regulator problems, are restricted to dynamic equations linear in state by virtue of using the convexity and compactness (Neustadt 1963) and contact function (Gilbert 1966) of the reachable set

This paper extends the above approach to a class of terminal cost optimal control problems similar to those considered by Barr and Gilbert (including quite general control constraints, but only allowing initial and final state constraints), having differential equations non-linear instate and control (where the convexity-compactness results do not hold), by converting each such problem to a sequence of optimal regulator problems, with non-linear differential equations. These, in turn, are solved by one of the author's earlier algorithms (Katz 1974) that makes use of the above convexity, compactness, and contact function results by repeatedly linearizing the regulator problems. The approach of this paper differs from that of Halkin (1964 b), in that Halkin directly linearizes the original problem (e.g. converting a non-linear minimum fuel problem to a linear minimum fuel problem) and then solves the linearized version by a doubly iterative procedure

The computing algorithm presented here is based on the definition of an appropriate approximate solution of the terminal cost problem. A local-minimum convergence proof is given, which is weak in the sense that it assumes convergence of the substep algorithm (Katz 1974) for non-linear optimal regulator problems, whose convergence has not been proved. A subsequent paper (Katz and Wachtor, to appear) shows good convergence of the (overall) terminal cost problem algorithm in examples having singular arcs, with no prior knowledge of the solution or its singular nature, other than an initial upper bound on the cost.     

Scalar-Lyapunov-function method for single- and multimachine problems in power systems

A systematic method is proposed to derive appropriate Lyapunov functions for single- and multimachine problems in power systems that will enable suitable stability-region estimates to be determined. Initially, the Lyapunov function for a simplified second-order system is derived. This function is then modified to form a suitable Lyapunov function for the actual non-linear system under study. Six examples for single- and multimachine problems are considered.     

NEW PROCEDURE FOR ESTIMATING THE MODULUS OF DEFORMABILITY OF CHEESE FROM UNIAXIAL COMPRESSION TESTS

The gradient of the inflection at the lowest strain in a stress versus strain curve was used to estimate the modulus of deformability (E_d) of cheese from the commonly used uniaxial compression test. The procedure required a sufficiently high sampling rate (e. g. 50 Hz at an initial strain rate of 0.0332 s⁻¹) to give data that provided fine structure to the measurements which is not usually reported. This procedure was based on the empirical observation that there was an initial concave up region prior to the usually reported concave down region of the curve for all samples studied. Numerical estimation of the gradient was used to locate the inflection point, and to estimate the gradient at that point. The procedure gave a well-defined measurement in the region of interest at small strain. It did not assume that all samples had the same strain region for compaction-dominating and fracture-dominating processes. Thus, in effect, it took account of the different strains at which E_d should be measured and eliminated differences in E_d between samples induced by differences in these processes. This procedure was compared with three existing procedures, for three cheeses. The procedure used responded differently to each cheese at the 1 % level. Values of E_d from the inflection point were similar to those from the gradient over 0.5 to 1.5 times the inflection strain, and higher than those from the gradient over 0 to 0.04 strain or from the linear term in a fiph order polynomial fit to the data up to fracture. The ranking of Ed for each cheese was the same for each procedure and the relative magnitude of Ed for each cheese was similar for each procedure.     

Routine fluorescence microscopy of single untethered protein molecules confined to a planar zone

To bypass limitations of ensemble averaging biochemical analysis, microscopy‐based detection and tracking are needed for single protein molecules that are diffusing in aqueous solution. Confining the molecules to a planar zone dramatically assists tracking. Procedures of microscopy should be routine enough so that effort is focused on the biochemistry. Fluorescence microscopy and partial planar confinement of single, untethered, aqueous protein molecules have been achieved here by use of a routine procedure. With this procedure, multiple thermally diffusing Alexa 488‐stained bovine serum albumin molecules were observed during partial confinement to a thin aqueous zone next to a cover slip. The procedure produces confinement by partial re‐swelling of a previously dried agarose gel on the microscope slide. Confinement was confirmed through analysis that revealed thermal motion lower in the third dimension than it was in the plane of observation.     

Synthesis-Fabrication of an Al2O3-Tungsten Carbide Composite

A composite of 70 vol% Al₂O₃ and 30 vol% tungsten carbide was formed by hot-pressing. Simultaneously carbon reacts with an intimate mixture of WO₃ and Al₂O₃ to form a dense body. The composite approached theoretical density; a 1- to -10-μm carbide phase was uniformly dispersed in a 2-μm Al₂O₃ matrix. Maximum density and fine-grained microstructure were obtained when pressure was applied during heating from 1200° to 1600°C and temperature and pressure were then maintained for 20 min. At an initial ratio of 2.8 and 2.9 mol C/mol WO₃, the tungsten appeared as free W, WC, and W₂C. For C/WO₃=3.0 to 3.6, mixtures of W₂C and WC were present, whereas for C/WO₃>3.6, free C appeared with WC. The effects of the hot-pressing parameters are discussed.     

Effects of Harvesting, Transportation, and Cryogenic Processing on the Microflora of Southern Peas

Samples of southern peas [Vigna unguiculata (L.) Walp., cv. Purple Hull Pinkeye] were obtained at critical stages in a normal harvesting, transportation, and cryogenic processing operation and microbiologically analyzed for total plate count (TPC), Enterobacteriaceae count (ENT), and yeast and mold counts. Molds were identified to genera while ENT were identified to species. Operations involving extended holding times tended to increase all counts significantly, although subsequent processing reduced these counts to an acceptable level. Predominant genera of ENT and molds appeared to be soil borne organisms such as Enterobacter agglomerans, Enterobacter cloacae, Klebsella pneumoniae, and Serratia liquefaciens, and Fusarium, Cladisporium, Alternaria, Phoma, and Aspergillus, respectively.     

APPLICATION OF SURFACE FRICTION MEASUREMENTS FOR SURFACE CHARACTERIZATION OF HEAT-SET WHEY PROTEIN GELS

The surface properties of heat‐set whey protein gels (14 wt %) was studied by measuring the friction at the gel's surface. A simple device was constructed that can be conveniently attached to a Texture Analyzer. Surface friction forces of gels with and without addition of salt were measured as a function of sliding speed and surface load. Surface friction strongly depended on the sliding speed for all three gel systems over the speed range 0.01 mm/s to 10 mm/s. The gel without salt addition showed the highest speed dependency, while the gel containing 200 mM NaCl had the lowest speed dependency. Surface load tests showed nearly linear relationships for both protein gels (with and without salt addition). Unlike solid materials, both protein gels exhibited a surface friction even as the surface load approached zero. Possible contributions of surface attraction and viscous flow to the measured forces are discussed. Results from surface friction tests were further confirmed by optical observation of the surface using a confocal laser scanning microscope (CLSM), where a very smooth surface was observed for the whey protein gel without salt addition, but a much rougher surface was observed for the gel containing 200 mM NaCl.