Identification of change structure in statistical process control

In order to diagnose properly quality problems that occur in manufacturing the diagnostician, be it human or computer, must be privy to various sources of information about the process and its behaviour. This paper describes how neural networks and Bayesian discriminant function techniques can be used to provide knowledge of how a product characteristic changed, i.e. shift in mean or variability, when so noted by the control chart application. Such information is useful because there usually exists some underyling knowledge about the physical phenomena in question that relates the behaviour of the observed characteristic to its processing variables. When a change in the process is detected by the appropriate statistical method, a feature vector of process-related statistics is used to identify the change structure as a shift in mean or variance. This paper addresses various issues concerned with this problem, namely: process change detection, feature vector selection, training patterns, and error rates. Simulation experiments are used to test various hypotheses and also compare the effectiveness of the two proposed approaches against two simpler heuristics. Results show the neural network and quadratic discriminant function approaches to be fairly similar, with a success rate of 94% and both to be superior to the simpler heuristic approaches.     

Pricing and ordering strategies in manufacturing and distribution alliances

This paper studies the effect of coordination in a manufacturing and distribution system consisting of one manufacturer and one distributor. The system operates to meet price-sensitive random demand with the objective of maximizing expected profits of both the manufacturer and the distributor. The coordinated pricing and production/ordering policies that maximize the expected profits of the manufacturer and the distributor, as well as the distributor's optimal pricing and ordering policies without coordination, are developed. The focus of this study is to address the following managerial questions: What factors make coordination an effective strategy for both the manufacturer and the distributor? What are the coordination strategies and the coordinated policies that maximize both parties' expected profits and the joint expected profit? These and other related managerial issues are explored in this paper.     

RHEOLOGICAL MODELING of POTATO FLOUR DURING EXTRUSION COOKING

A generalized model for predicting the effects of shear rate, temperature, moisture content, time-temperature history and strain history on viscosity has been evaluated for extruded potato flour doughs. an Instron Capillary Rheometer and a 50 mm Baker Perkins co-rotating twin screw extruder were used to evaluate all effects incorporated in the model, except strain history. the power law model was used to describe shear rate effects in the range 10–10000 s^?1. the generalized model fit observed data for temperatures of 25–95°C and moisture contents ranging from 22 to 50%, wet basis. Since potato flour by its manufacturing process is pregelatinized, it was unnecessary to evaluate the effects of time-temperature history. Strain history was found to have an insignificant influence on the viscosity.     

FACTORS AFFECTING THE ULTRAVIOLET INACTIVATION OF ESCHERICHIA COLI K12 IN APPLE JUICE AND A MODEL SYSTEM*

Ultraviolet (UV) light has been used successfully for years to sterilize water and was recently approved as an acceptable irradiation treatment for the processing of juice. Although there is considerable information on the efficacy of UV processing in the treatment of water, limited data are available on its efficacy in fluid food systems. The objectives of this work were to determine the effects of apple‐juice properties on the UV inactivation of Escherichia coli K12 and the interdependence of intensity and time on the efficacy of UV light. Results showed that absorbance (A) and suspended solids (SS) affected UV inactivation, while pH and dissolved solids did not. Concerning the interdependence of intensity and time, intensity levels can only be changed without sacrificing effectiveness at a limited range of intensity and dose levels. This means that the range of the intensity level of the actual UV reactor must be considered in process‐parameter determination.     

Strategies for integrating lead time and customer-order decisions

Make-to-order manufacturers are facing unprecedented challenges to fill their customer orders quickly and to reduce their operating costs. In this paper, we first describe and discuss order taking and lead time quoting practice in a real world make-to-order manufacturing system. We then develop a model for this practical problem to study the conflicting objectives, of delivering customized orders quickly and maximizing expected profit. The primary goal of this paper is to develop a general model for studying the trade-offs and the interrelationships among the following manufacturing performance measures: manufacturing flow times, quoted lead time reliability (earliness and tardiness), throughput (or demand) rates, inventory levels, resource utilization, and expected profits. These and other related managerial issues are explored. Our structural results yield insights into basic choices between filling customer orders quickly and maximizing expected profit.     

EFFECTS OF DARK STORAGE TIME AND UV-FILTERED FLUORESCENT LIGHTING DURING DISPLAY ON COLOR STABILITY OF HIGH-OXYGEN MODIFIED ATMOSPHERE PACKAGED GROUND BEEF

Effects of temperature (OC and 4.4C) during dark storage (days 2-9) and display in non-UVand UV-filtered fluorescent lighting on color stability of high-O₂ modified atmosphere packaged "case ready" ground beef was evaluated. Minimal shift in headspace O₂ and CO₂ concentrations occurred during 9 days of storage and display. By day 3, product stored at 4.4C lost redness (Hunter +a) faster than that held at OC. Visual panel ratings for lean color decreased (P > 0.05) after 7 days but were not affected by storage temperature. When packages stored 2, 4, or 6 days at OC were displayed in light, Hunter +a values did not decline (P <0.05) for the first day and in several instances were maintained for 2 days. Panel evaluations of displayed product substantiated high maintenance of redness of lean color. UV-filtering of fluorescent lighting was not necessary for color stability of ground beef during display.     

EFFECT OF INSOLUBLE PARTICLES UPON SOLID INCLUSION LEVELS IN ICE FORMED ON A SUBCOOLED STAINLESS STEEL SURFACE

This study employed an insoluble solid particle, i.e. a potato starch used as an example, to investigate the impact of the concentration of such particles suspended in water (with solid loading of 5, 10, 20 and 30 wt%) upon the solid inclusion levels in ice layers formed on a sub‐cooled smooth stainless steel plate surface. The effects of ice growth rate, bulk concentration and suspension velocity on insoluble solid inclusion, i.e. potato starch mass fraction, in ice layer were studied. The experiments, where potato starch is added into aqueous sucrose solutions or the reverse where sucrose is added into starch suspension, were also carried out to investigated effect of the starch particles on sucrose inclusion in ice and effect of solute (sucrose) on starch particle inclusion in ice. It has been found that solid inclusion in ice increases with increasing bulk concentration and average ice growth rate, at constant solution and coolant velocities, and increasing suspension velocity can help pure ice formation. The average distribution coefficient of sucrose in ice layer formed from sucrose solution does not appear to be affected by the addition of potato starch. However, the average distribution coefficient of potato starch in ice layer formed from suspension is influenced by sucrose concentration quite significantly.