Scheduling Paradigm Research Articles

A paradigm for computer-assisted radiology resident rotation scheduling

The scheduling of radiology residents remains a major annual undertaking of chief residents. In this article, we describe a paradigm to implement interactive computer programs to reduce the inefficiencies and inequities of planning the yearly schedule. We used the programming language, Prolog, to develop a compact program that provides faster and more flexible performance than those reported in the literature. This interactive program stores scheduling requirements in data files separated from the control program and runs on a Macintosh computer. The schedule of any residency year is generated within 3-7 sec. The fast computation and query capabilities of this scheduling program have helped chief residents to identify conflicting requirements that were previously overlooked. Using our programming paradigm, we have developed a portable Prolog-based scheduling program that is quick and easy to use.

CYANAMIDE ON ETHANOL INTAKE: HOW DOES IT REALLY WORK?

Cyanamide, an aldehyde dehydrogenase inhibitor, has been shown to suppress voluntary ethanol consumption in animals. Studies were carried out to compare the effect of cyanamide on ethanol, saccharin-quinine and water intake in a restricted (10 min) access and in a free-choice nonrestricted access paradigm. An immediate and constant increase in fluid consumption was observed in the restricted access schedule paradigm independent of the fluid tested as cyanamide affected the consumption of all fluids including water. In the nonrestricted access study, cyanamide significantly increased total fluid intake. However, while saccharin-quinine-drinking animals treated with cyanamide demonstrated no change in intake preference, ethanol consumption was suppressed with a concomitant decrease in preference for ethanol. The present findings suggested that cyanamide may possess at least two, paradigm-specific, independent properties. It may enhance the consumption of fluid in general; however, it may also have a specific effect on ethanol intake when animals have continuous ethanol availability.

PERT-BASED PARADIGM FOR MODELING ASSEMBLY OPERATIONS

This paper uses a PERT network for which operation start and finish times are approximated by mixtures of Erlang distributions as the basis of a paradigm for modeling assembly operations. Numerical examples demonstrate that the approximations improve on previously available methods and give accurate estimates in cases involving operation times that are mixtures of Erlangs, exponential, or normal. In addition, a new method of computing lower bounds on operation start times is derived; numerical tests indicate that the method gives tighter bounds than do previously available methods. The significance of the paradigm is discussed, emphasizing the improvement it makes over traditional scheduling paradigms.

Scheduling with flexible process plans

Abstract When a process planning module is embedded into the scheduling paradigm, the solution space of the scheduling problem is expanded due to possible generation and use of alternative process plans, i.e. the combined system of process planning and scheduling is equivalent to scheduling with flexible process plans. This flexibility provides a potential for obtaining improved schedules, but it increases the complexity of the structure of the scheduling problem. This paper describes a solution approach for the integrated system and analyses the performance of a new algorithm under various simulated scenarios.

Predictable Real-Time Caching in the Spring System

Real-time system designers must predict the behavior of the system at development time. The predictions most often used are for worst case execution time, and must consider the properties of the system within which the programs are executed. The most obvious factor is the execution times of CPU instructions, which are significantly affected by the presence of a cache. A WCET estimate is valid if it is greater than or equal to the actual WCET. This paper addresses the problem of how to make valid predictions about the effects of caching on the WCET. Our predictions of the cache’s effects depend on the scheduling paradigm around which the system is designed. We discuss the rate monotonic and Spring paradigms, and discuss how the differences in their properties affect our ability to consider caches in WCET calculation. We also discuss to what extent we can predict the effects of caches on the system, and the extent to which these predictions can be used to reduce the pessimism of WCET estimates while preserving their validity. Finally, we describe some of the open problems we are considering.

Behavioral economic analysis of smoking: Money and food as alternatives

The relative reinforcing value of smoking versus two nonpharmacological reinforcers, money and food, was evaluated in young female smokers in two experiments. In experiment 1 eight smokers worked for access to smoking or money on concurrent progressive variable ration schedules of reinforcement (VR4 to VR50) across two days of Smoking Deprivation or No Deprivation. During No Deprivation money was reliably chosen over smoking. During Deprivation subjects initially (VR4) chose smoking over money, but at subsequent comparisons allocated equal time to work for smoking or money. In Experiment 2 eight smokers were provided access to smoking or food across four conditions: No Deprivation, Smoking Deprivation, Food Deprivation and Smoking + Food Deprivation, using the same progressive variable ratio schedules as in Experiment 1. Results showed an increase in the reinforcing value of food after Food Deprivation and smoking after Smoking Deprivation. On the dual deprivation day, subjects initially (VR4) chose to work for food, showed equal preferences over the next three schedule comparisons (VR8–VR20), and from VR25–VR50 shifted their choice to smoking. An increase in percent of calories as fat was observed during all deprivation conditions. The results demonstrate the use of the concurrent schedule paradigm for assessing choice among pharmacological and nonpharmacological reinforcers, and shows the relative reinforcing value of smoking depends on recent deprivation, response demands to obtain the reinforcer and availability of alternative reinforcers.

A recent survey of production scheduling

Recent advances in the theory and practice of production scheduling cut across traditional disciplinary boundaries. Different research communities have addressed different aspects of the problem, bringing to bear a variety of research traditions, problem perspectives, and analytical techniques. The breadth and practical implications of contemporary work in this field is assessed. A structured overview, a high-level bibliography, and a limited critique of seven scheduling paradigms are provided. The sense and direction of current developments in each of these seven areas are summarized. The contributions, strengths, and weaknesses of each approach are considered. >

Efficient Storage Management for Temporary Values in Concurrent Programming Languages

An evaluation stack, used exclusively to store temporary values in expression evaluation, is known to be an effective mechanism in the implementation of high level languages. This work considers the efficient management of evaluation stacks for concurrent programming languages. Techniques for sharing a single evaluation stack among many processes, without copying on process switches, are developed. The best strategy for managing the evaluation stack is shown to depend strongly upon the scheduling paradigm adopted by the run-time support of the language. Simulation studies, driven by synthetic workloads, show that the techniques described in this paper exhibit substantial performance improvements over traditional temporary storage management schemes for concurrent languages.

Influence of intravenous self-administered psychomotor stimulants on performance of rhesus monkeys in a multiple schedule paradigm.

Rhesus monkeys were trained to complete three multiple schedules. The schedules consisted of three components: a fixed interval (component 1), a variable interval (component 2), and a fixed ratio (component 3). During components 1 and 2, pressing lever 1 was always reinforced by food delivery. During component 3, pressing lever 2 resulted in either food delivery or intravenous infusions of saline solution, solutions of cocaine, of d-amphetamine, of phenmetrazine, or fenetylline. In schedule I, animals were presented with all three components independent of key-pressing behavior during components 1 and 2. In schedule II the availability of component 2 was dependent on completion of component 1. Component 3 was made available only on completion of component 2. Noncompletion of components 1 or 2 resulted in time-out of 15 and 10 min, respectively. Schedule III was identical with schedule II, except that in schedule III the completion of components was indicated only by a change in the lever lights. The influence of self-administered drugs on behavior in all three components was evaluated. Self-administration of psychomotor stimulants impaired the performance of animals and delayed completion of components 1 and 2 of schedules I, II, and III. The effects on behavior were similar with low drug intake in schedule III, moderate intake in schedule II, and high drug intake in schedule I. These effects were strong with self-administration of phenmetrazine, moderate with self-administration of cocaine and d-amphetamine, and weak with self-administration of fenetylline.

Disinhibitory effects of intrahippocampal or intrahypothalamic injections of anticholinergic compounds in the rat

The effects of intrahippocampal or intrahypothalamic injections of anticholinergic compounds on operant responding were observed in a multiple schedule paradigm consisting of reinforced, punished, and nonreinforced components and on a punished ingestive passive avoidance task. The pattern of results suggests that cholinergic components of the hippocampus and hypothalamus mediate responding suppressed by nonreinforcement but not by punishment. The data are discussed with reference to Carlton's proposed central cholinergic inhibitory mechanisms.

Schedule interactions in second-order fixed-interval (fixed-ratio) schedules of token reinforcement

Three rats performed in an extended behavior sequence in which lever pressing was maintained on an FR 20 schedule of token reinforcement. Fixed-interval exchange schedules were varied from FI 1.5 min to FI 9.0 min, and during exchange the schedule of food reinforcement was FR 1. The FR 20 schedule of token reinforcement and the FI exchange schedules interacted to produce patterns of responding appropriate to each schedule. Overall response rates declined as the FI exchange schedule was increased in duration. The general token reinforcement paradigm was discussed in terms of its similarities with the chained schedule paradigm and the secondorder schedule paradigm with brief-stimulus presentations.