Progress in integrating and optimizing production plans and schedules

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.     

Particle Size Effects on the Diffuse Reflectance of a Sucrose-Caramel Admixture

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.     

犊牛的管理

针对国内牛场管理方面专门论述较少,从犊牛管理实践出发,简要介绍了犊牛识别系统、犊牛的去角、犊牛垫料的选择与管理、犊牛奶桶的正确洗涤方法、犊牛饲料的存放以及劳动力的管理等内容,对管理内容进行了界定和阐述。     

Analysis of a two-dissimilar unit cold standby redundant system subject to inspection and random change in units

This paper deals with the stochastic behaviour of a two-dissimilar unit cold standby redundant system with random change in units. In this system each unit works in two different modes—normal and total failure. It is assumed that the failure, repair, post repair, interchange of units and inspection times are stochastically independent random variables, each having an arbitrary distribution. The system is analysed by the semi-Markov process technique. Some reliability measures of interest to system designers as well as operations managers have been obtained. Explicit expressions for the Laplace-Stieltjes transforms of the distribution function of the first passage time, mean time to system failure are obtained. Certain important results have been derived as particular cases.     

UPGRADING SPENT LAYER MEAT BY MECHANICAL DEBONING AND FURTHER PROCESSING

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.     

Elastic Moduli of Glasses by a Dynamic Method

The elastic moduli and speed of sound of twenty-three optical glasses, a series of Na₂O₃, CaO₃, SiO₃, and B₂O₃ 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.     

Elastic Moduli of Glasses at Elevated Temperatures by a Dynamic Method

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.