Studies in a Simulated Job Shop

1975 ◽  
Vol 189 (1) ◽  
pp. 417-426 ◽  
Author(s):  
Samuel Eilon ◽  
I. G. Chowdhury
Keyword(s):  
Waiting Time ◽  
Job Shop ◽  
Batch Size ◽  
Due Dates ◽  
Operational Flexibility ◽  
Time Intervals ◽  
Empirical Relationships ◽  
Regular Time ◽  
One Machine

The effectiveness of various scheduling or loading rules in a job shop has been widely studied through simulation, where a given shop can be subjected to alternative patterns of arrivals and processing. This study is particularly concerned with the case when arrivals are in batches, either of regular size or where the batch size is Poisson distributed, and when the batches arrive at regular time intervals, and certain empirical relationships between three loading rules are investigated. Two types of operational flexibility are examined, the first where more than one machine may perform a given operation and the second where changes in the sequence of operations are allowed, and the effect of such flexibilities on the expected job waiting time is determined. Finally, the effect of different procedures for determining due-dates for arriving jobs is investigated.

scholarly journals Speech rhythm: a metaphor?

2014 ◽  
Vol 369 (1658) ◽  
pp. 20130396 ◽  
Author(s):  
Francis Nolan ◽  
Hae-Sung Jeon
Keyword(s):  
Traditional View ◽  
Time Intervals ◽  
Speech Rhythm ◽  
Linguistic Structure ◽  
Regular Time ◽  
Linguistic Functions ◽  
Absence Of Evidence ◽  
Metaphorical Extension ◽  
Analogical Process

Is speech rhythmic? In the absence of evidence for a traditional view that languages strive to coordinate either syllables or stress-feet with regular time intervals, we consider the alternative that languages exhibit contrastive rhythm subsisting merely in the alternation of stronger and weaker elements. This is initially plausible, particularly for languages with a steep ‘prominence gradient’, i.e. a large disparity between stronger and weaker elements; but we point out that alternation is poorly achieved even by a ‘stress-timed’ language such as English, and, historically, languages have conspicuously failed to adopt simple phonological remedies that would ensure alternation. Languages seem more concerned to allow ‘syntagmatic contrast’ between successive units and to use durational effects to support linguistic functions than to facilitate rhythm. Furthermore, some languages (e.g. Tamil, Korean) lack the lexical prominence which would most straightforwardly underpin prominence of alternation. We conclude that speech is not incontestibly rhythmic, and may even be antirhythmic. However, its linguistic structure and patterning allow the metaphorical extension of rhythm in varying degrees and in different ways depending on the language, and it is this analogical process which allows speech to be matched to external rhythms.

Processing and Excellent Oxidation Resistance of Nanocrystalline Fe-Cr Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 1122-1125
Author(s):  
Rajeev K. Gupta ◽  
B.V. Mahesh ◽  
R.K. Singh Raman ◽  
Carl C. Koch
Keyword(s):  
Oxidation Resistance ◽  
Secondary Ion Mass Spectrometry ◽  
Nanocrystalline Alloy ◽  
High Energy ◽  
Processing Route ◽  
Protective Oxide ◽  
Time Intervals ◽  
Regular Time ◽  
Order Of Magnitude ◽  
Energy Ball

Nanocrystalline and microcrystalline Fe-10Cr alloys were prepared by high energy ball milling followed by compaction and sintering, and then oxidized in air for 52 hours at 400°C. The oxidation resistance of nanocrystalline Fe-10Cr alloy as determined by measuring the weight gain after regular time intervals was compared with that of the microcrystalline alloy of same chemical composition (also prepared by the same processing route and oxidized under identical conditions). Oxidation resistance of nanocrystalline Fe10Cr alloy was found to be in excess of an order of magnitude superior than that of microcrystalline Fe10Cr alloy. The paper also presents results of secondary ion mass spectrometry of oxidized samples of nanocrystalline and microcrystalline Fe-Cr alloys, evidencing the formation of a more protective oxide scale in the nanocrystalline alloy.

One-of-a-kind Production in Cyber-Physical Production Systems Considering Machine Failures

2021 ◽  
pp. 1-20
Author(s):  
Guido Vinci Carlavan ◽  
Daniel Alejandro Rossit
Keyword(s):  
Industry 4.0 ◽  
Information Technologies ◽  
Job Shop ◽  
Production Systems ◽  
Dispatching Rules ◽  
Shop Floor ◽  
Due Dates ◽  
Efficient Manner ◽  
Large Variability ◽  
Cyber Physical Production Systems

Industry 4.0 proposes the incorporation of information technologies at all levels of the production process. By incorporating these technologies, Industry 4.0 provides new tools for production planning processes, allowing to address problems in an innovative and efficient manner. From these technologies and tools, it is that in this work a One-of-a-Kind Production (OKP) process is approached, where the products tend to be highly customized. OKP implies working with a very large variability within production, demanding very efficient planning systems. For this, a planning model based on CONWIP-type strategies was proposed, which seeks to level the production of a shop floor configured in the form of a job shop. Even more, for having a more realistic shop-floor representation, machine failures have been included in the model. In turn, different dispatching rules were proposed to study the performance and analyze the behaviour of the system. From the results obtained, it is observed that, when the production demand is very exigent in relation with the capacity of the system, the dispatching rules that analyze the workload generated by each job tend to perform better. However, when the demand on the capacity of the production system is less intense, the rules associated with due dates are the ones that obtain the best results.

scholarly journals Simulation modeling and analysis of job release policies in scheduling an agile job shop with process sequence dependent setting time

2017 ◽  
Vol 7 (1.1) ◽  
pp. 177 ◽  
Author(s):  
K.T. Vinod ◽  
S. Prabagaran ◽  
O.A. Joseph
Keyword(s):  
Simulation Model ◽  
Job Shop ◽  
Statistical Tests ◽  
Setting Time ◽  
Performance Criteria ◽  
Analytical Models ◽  
Due Dates ◽  
Priority Rules ◽  
Work In Process ◽  
Sequence Dependent

This paper analyses the effects of job release policies, priority scheduling rules and setup times on the performance of a dynamic job shop in a sequence dependent setup time environment. Two job release policies namely, immediate job release and job release based on a specified work-in-process are investigated. A simulation model of a realistic manufacturing system is developed for detailed analysis. The dynamic total work content method is adopted to assign the due dates of jobs. Six priority rules are applied for prioritizing jobs for processing on machines. Several performance criteria are considered for analyzing the system performance. The simulation results are used to conduct statistical tests. Analytical models have been formulated to represent the simulation model for post-simulation studies. These models are found to yield a satisfactory estimation of the system outputs.

A Method for Quantitative Analysis of the Kinematics of Fibroblast Migration in a Monolayer Wound Model

2011 ◽  
Author(s):  
Gil Topman ◽  
Orna Sharabani-Yosef ◽  
Amit Gefen
Keyword(s):  
Wound Healing ◽  
Cell Migration ◽  
Wound Healing Assay ◽  
Complete Coverage ◽  
Time Intervals ◽  
Fibroblast Migration ◽  
Wound Model ◽  
Regular Time

A wound healing assay is simple but effective method to study cell migration in vitro. Cell migration in vitro was found to mimic migration in vivo to some extent [1,2]. In wound healing assays, a “wound” is created by either scraping or mechanically crushing cells in a monolayer, thereby forming a denuded area. Cells migrate into the denuded area to complete coverage, and thereby “heal” the wound. Micrographs at regular time intervals are captured during such experiments for analysis of the process of migration.

scholarly journals Optimasi Tingkat Layanan Call Center Jasa Teleponi Dasar: Kajian Regulasi

2019 ◽  
Vol 9 (3) ◽  
pp. 151
Author(s):  
Hendro Purwadi
Keyword(s):  
Waiting Time ◽  
Call Center ◽  
Interactive Voice Response ◽  
Demand Curve ◽  
Comparative Method ◽  
Supply And Demand ◽  
Service Level ◽  
Time Intervals ◽  
Business Approach ◽  
Voice Response

Service level in the call center is calculated based on the number of calls answered during the certain time intervals compared to the total number of calls received. The measurement of service level on the call center operator starts when the caller presses the menu to talk to the  operator on interactive voice response (IVR) menu, and is expressed as a percentage. The higher expected percentage of service level will be higher the needs of operator in the services.  Regulation in Indonesia determines service level for the call center of Basic Telephony Services is in the amount of more than or equal to 90% in 30 seconds. The author uses a business approach to the operational of the call center to analyze existing statutory data. Through the comparative method between operator occupancy and the costs required for the operation of call center using supply and demand curve, the optimum service level value at the call center of Basic Telephony Services can be known, which is 85% in 25 seconds. This means that 85% of incoming calls must be answered by the operator with a maximum waiting time of 25 seconds.

scholarly journals Using approximate Bayesian inference for a “steps and turns” continuous-time random walk observed at regular time intervals

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8452
Author(s):  
Sofia Ruiz-Suarez ◽  
Vianey Leos-Barajas ◽  
Ignacio Alvarez-Castro ◽  
Juan Manuel Morales
Keyword(s):  
State Space ◽  
Continuous Time ◽  
Time Scale ◽  
Animal Movement ◽  
State Space Model ◽  
Movement Direction ◽  
Time Intervals ◽  
Space Model ◽  
Regular Time ◽  
Approximate Bayesian

The study of animal movement is challenging because movement is a process modulated by many factors acting at different spatial and temporal scales. In order to describe and analyse animal movement, several models have been proposed which differ primarily in the temporal conceptualization, namely continuous and discrete time formulations. Naturally, animal movement occurs in continuous time but we tend to observe it at fixed time intervals. To account for the temporal mismatch between observations and movement decisions, we used a state-space model where movement decisions (steps and turns) are made in continuous time. That is, at any time there is a non-zero probability of making a change in movement direction. The movement process is then observed at regular time intervals. As the likelihood function of this state-space model turned out to be intractable yet simulating data is straightforward, we conduct inference using different variations of Approximate Bayesian Computation (ABC). We explore the applicability of this approach as a function of the discrepancy between the temporal scale of the observations and that of the movement process in a simulation study. Simulation results suggest that the model parameters can be recovered if the observation time scale is moderately close to the average time between changes in movement direction. Good estimates were obtained when the scale of observation was up to five times that of the scale of changes in direction. We demonstrate the application of this model to a trajectory of a sheep that was reconstructed in high resolution using information from magnetometer and GPS devices. The state-space model used here allowed us to connect the scales of the observations and movement decisions in an intuitive and easy to interpret way. Our findings underscore the idea that the time scale at which animal movement decisions are made needs to be considered when designing data collection protocols. In principle, ABC methods allow to make inferences about movement processes defined in continuous time but in terms of easily interpreted steps and turns.

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