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Over the past twenty years two widely accepted approaches to integrated production planning and scheduling systems have emerged. The first approach was based on materials requirements planning (MRP). This approach emphasizes minimizing inventory while meeting order due dates. The second approach was heirarchical production planning (HPP). This approach emphasizes cost minimization and efficient utilization of capacity. This paper reviews the evolutionary development of each of these integrated systems and concludes by discussing the environment where each is best suited. 相似文献
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Decreasing the particle size of homogeneous colorant (caramel) from 68 to 28 microns increased lightness as predicted by the Kubelka-Munk theory. The presence of diluent (sucrose) reversed particle size effects, i.e., reduced caramel particle size decreased mixture lightness. Decreasing the particle size of the diluent, however, substantially increased the diffuse reflectance of the admixture, lowering its color intensity. The degree of color masking was determined mainly by the particle size of sucrose and to a much lesser extent by that of caramel. The dilution ratio and particle size of both colorant and diluent could be used to control the color of many food systems. 相似文献
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Spent layer chickens, an underutilized, inexpensive source of animal protein in the United States, were used to produce an acceptable all chicken frank following mechanical deboning of the chicken parts without pregrinding. The franks were subjected to shear tests and compared to two well-known commercial brands of chicken franks for overall acceptability by an untrained 59 member panel. The franks produced from mechanically deboned spent layer chickens (Lab franks) had greater resistance to shear than the two commercial brands and the panelists showed significantly greater preference for one of the commercial brands. Comments of the panelists indicated the texture of the lab-prepared franks was tougher than the two commercial brands. However, 12 members of the panel stated the lab-frank texture was tender. Collagen content of the spent layer franks was no higher than for the commercial brands. It is therefore concluded that the toughness could have been due to the nature of the myofibrillar proteins. Such toughness could be modified by tenderizing enzyme treatment of the raw material to produce varying degrees of frank softness or firmness depending on consumer preference. 相似文献
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SAM SPINNER 《Journal of the American Ceramic Society》1954,37(5):229-234
The elastic moduli and speed of sound of twenty-three optical glasses, a series of Na2 O3 , CaO3 , SiO3 , and B2 O3 glasses, and some specimens of fused silica were measured by a dynamic method. Each specimen, in the shape of a prismatic bar, was vibrated in four different ways: longitudinally, flexurally on the wide side, flexurally on the thin side, and torsionally. Good agreement was found on Young's modulus as determined by the first three methods. The torsional mode was used to obtain the shear modulus. Statically and dynamically determined values of Young's modulus for six sample glasses also showed good agreement. 相似文献
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SAM SPINNER 《Journal of the American Ceramic Society》1956,39(3):113-118
The elastic constants of thirteen glasses were measured by a dynamic method at elevated temperatures. Both Young's modulus and the shear modulus were determined and from these Pois-son's ratio was calculated as a function of temperature. Fused silica, Vycor-brand glass, and Pyrex-brand glass had positive temperature coefficients of elastic moduli, whereas all the other glasses showed negative coefficients. Poisson's ratio was found to rise with temperature in all thirteen glasses. This is interpreted as an indication of an approach to the liquid state. 相似文献
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The present study describes the inhibition of aluminium in 1N HNO3 with different concentrations of 1,2,4-triazole precursors ATD, BATD and DBATD using gravimetric method, potentiodynamic
polarization studies (Tafel), electrochemical impedance spectroscopy (EIS), adsorption studies, surface morphological studies
and quantum chemical calculations at 298 K. Polarization studies clearly showed that ATD, BATD and DBATD act as mixed type
inhibitors. As the electron density around the inhibitor molecule increases due to substitution, the inhibition efficiency
also increases correspondingly. Quantum chemical approach was used to calculate some electronic properties of the molecule
to ascertain the correlation between inhibitive effect and molecular structure of the inhibitor. The corrosion inhibition
efficiencies of these molecules and the global chemical reactivity relate to some parameters, such as E
HOMO
, E
LUMO
, gap energy (ΔE), electronegativity (χ), global hardness (η) and the fraction of electrons transferred from the inhibitor molecule to the metallic atom (DN\Delta \emph{N}). In addition, the local reactivity has been analysed through the Fukui function and condensed softness indices. Both the
experimental and theoretical studies agree well in this regard and confirm that DBATD is a better inhibitor than BATD and
ATD. The adsorption behaviours of molecules on the copper surface have been studied using molecular dynamics method and density
functional theory. The order of inhibitory action is DBATD > BATD > ATD. 相似文献