International Journal of Industrial Engineering: Theory, Applications and Practice
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VR-Based Robot Programming and Simulation System for an Industrial Robot
Get PDFTraditional robot programming such as teach by lead etc have been used for many years. These methods are considered not efficient and outdated in the current industrial and market demands. In this paper, virtual reality (VR) technology is used to improve human-robot interface - no complicated command or programming knowledge is required. The system is divided into three major parts: task teaching by demonstration in a computer generated virtual environment, a graphical robot simulator with intelligent robot command generator and last but not least, real task execution. The user is requested to complete the desired task in a virtual teaching system by wearing a data glove attached with a sensor tracker. The process path will be simulated and analyzed to obtain the optimum trajectory. Robot motions can be checked through the simulation program and robot program can be generated for the real task execution
Centroid – A Widely Misunderstood Concept In Facility Location Problems
Get PDFThe aim of this paper is to show, by use of a complete and exact mathematical model, that the centroid method is a widely misunderstood method in facility location problems and that it is, in fact, normally an inappropriate method to use for such problems. While numerous sources do describe the procedure as minimizing the total shipping cost when transportation costs are linearly proportional to the distances of travel, this study shows that these statements are not valid. The misunderstanding regarding what the centroid method actually does results from an improper interpretation of the notion of the center of gravity. In fact, the centroid method minimizes shipping costs only if transportation costs are proportional to the squares of distances traveled.
EFFECT OF SIMULATED APPOINTMENT SCHEDULES ON THE OPERATIONAL PERFORMANCE OF A UNIVERSITY MEDICAL CLINIC
No full textHigh patient wait times, physician idle times, physician overtimes, and patient congestion are common problems encountered in clinics that add to health care costs. This paper investigates the effect of different appointment systems on the operational performance of a university clinic. The process at a student health center was modeled using the Rockwell Arena® simulation software. Individual Block rule, Bailey rule, 3-Bailey rule, and the Two-at-a-time rule were compared using the simulation model to test their effect on performance parameters. The performance parameters were the provider measures and patient measures. The individual block rule was the most patient-friendly with the shortest patient measures. The 3-Bailey rule was the most provider-friendly rule, which resulted in the least provider times. A Kepner-Tregoe analysis shows that the Bailey rule was the most suitable as it had a good trade-off between the patient and provider times compared to the others
INTEGRATED APPROACH OF SCHEDULING A FLEXIBLE JOB SHOP USING ENHANCED FIREFLY AND HYBRID FLOWER POLLINATION ALGORITHMS
Get PDFManufacturing industries are undergoing tremendous transformation due to Industry 4.0. Flexibility, consumer demands, product customization, high product quality, and reduced delivery times are mandatory for the survival of a manufacturing plant, for which scheduling plays a major role. A job shop problem modified with flexibility is called flexible job shop scheduling. It is an integral part of smart manufacturing. This study aims to optimize scheduling using an integrated approach, where assigning machines and their routing are concurrently performed. Two hybrid methods have been proposed: 1) The Hybrid Adaptive Firefly Algorithm (HAdFA) and 2) Hybrid Flower Pollination Algorithm (HFPA). To address the premature convergence problem inherent in the classic firefly algorithm, the proposed HAdFA employs two novel adaptive strategies: employing an adaptive randomization parameter (α), which dynamically modifies at each step, and Gray relational analysis updates firefly at each step, thereby maintaining a balance between diversification and intensification. HFPA is inspired by the pollination strategy of flowers. Additionally, both HAdFA and HFPA are incorporated with a local search technique of enhanced simulated annealing to accelerate the algorithm and prevent local optima entrapment. Tests on standard benchmark cases have been performed to demonstrate the proposed algorithm’s efficacy. The proposed HAdFA surpasses the performance of the HFPA and other metaheuristics found in the literature. A case study was conducted to further authenticate the efficiency of our algorithm. Our algorithm significantly improves convergence speed and enables the exploration of a large number of rich optimal solutions.
PERFORMANCE OF TWO-SIDED EWMA CEV CONTROL CHARTS WITH MULTIPLE CENSORED DATA
No full textControl charts are widely applied in process control. Life testing is time-consuming and expensive; thus, this testing typically has a termination condition that is based on the assumption of a single failure mode. The lifetimes of unfailed units are known as right-censored data, and conditional expected value (CEV) control charts are effective for monitoring right-censored data. However, life testing may produce multiple censored data due to there being multiple failure modes. The occurrence of these failure modes is unpredictable, and thus the censored proportion cannot be known in advance. The exponentially weighted moving average (EWMA) control chart has a high sensitivity for detecting small mean shifts. In this paper, two charting methods for monitoring multiple censored data were developed: a two-sided EWMA CEV control chart and a combination of two single-sided EWMA CEV charts. A multi-objective model was established to optimize the design parameter values for the two types of control charts by using the multi-objective genetic algorithm. The charting methods were compared theoretically and with the practical example of liquid crystal display modules. The results demonstrate that the two-sided EWMA CEV control chart is generally more effective than the combination of two single-sided EWMA CEV control charts for monitoring multiple censored data. Moreover, if a large range and high censoring proportion are used to optimize the model design, increasing the sample size can always improve the performance of the EWMA CEV control chart
A SYSTEM DYNAMICS MODEL ASSESSING THE SUSTAINABILITY OF THE PERFORMANCE OF SUPPLY CHAINS WITH REVERSE FLOW
No full textSustainability in supply chains is more important than ever. In this paper, we consider a supply chain with a reverse flow where customers can return or replace products that flow backward to upstream members. The returned products re-enter the forward flow after different adjustments. We focus on measuring how the different operational parameters affect the sustainability of the supply chain and whether their interaction may affect the sustainability measures or not. The sustainability dimensions considered here are the social and environmental dimensions. A system dynamics model is developed for a supply chain with reverse flow. The proposed model measures the social dimension in terms of customer satisfaction and the environmental dimension in terms of the green image factor. We run the model for different parameters, and a factorial analysis is conducted on the results to show their main effect and their interaction effect on the measures under study. The results show how each of the main factors affects the sustainability of the supply chain; and how the interactions between the different factors can improve the already conflicting nature between the environmental and social performance measures
Scheduling Maintenance Activities During Planned Outages At Nuclear Power Plants
Get PDFIn order to maintain high production rates, electric power as well as manufacturing plants shut down so that maintenance activities can be performed on machines/equipment. These planned shut downs (outages) usually occur at least once a year and are more frequent for plants with older machines/equipment. The major costs associated with outages are cost of materials, labor cost, and loss of production cost. Due to high cost incurred from loss of production, the objective is to schedule maintenance activities such that outage duration is minimized. Since the resources required to perform maintenance activities are very limited, the problem of scheduling the maintenance activities is defined as a resource constrained project scheduling problem (RCPSP). In this paper, a solution technique, which consists of a simulated annealing heuristic, is presented for the RCPSP
Performance Analysis of Flowshop Scheduling Using Genetic Algorithm Enhanced with Simulation
Get PDFThis paper uses the genetic algorithm combined with simulation techniques to evaluate the performance of flowshop scheduling. The problem of scheduling is a NP combinatorial optimization problem. The objective of the study is to develop robust scheduling by using Genetic Algorithms (GA) to obtain good solutions may be close to optimum sequence with minimum cycle time or make span time for a flow shop problem. The next step is to use simulation to analyze the performance of selected sequences to achieve better resource utilization. In this research, newly hybrid genetic algorithm is developed using C-programming language for four different methods to solve flow shop scheduling problems. The proposed methods are implemented on a number of tested problems and compared with exact solutions on smaller scale problems. The alternative sequence obtained here is further analyzed by simulating the production model using ARENA software
A COMBINED AHP-ENTROPY METHOD FOR DERIVING SUBJECTIVE AND OBJECTIVE CRITERIA WEIGHTS
Get PDFThis paper investigates the problem of deriving subjective and objective criteria weights, by combining the AHP and Shannon's entropy method. The paper outlines the challenge of making preferential judgments based on non-homogeneous decision data and variant decision knowledge. Such decision complexity often leads to inaccurate assessment of criteria weights, and consequently reducing the credibility of decisions. The combined AHP-entropy method conforms to the type of decision data (qualitative or quantitative; deterministic or probabilistic) and to the degree of decision knowledge (none, partial, or full preferential judgments). An easy-to-apply spreadsheet-based application program of the unified AHP-entropy method is developed for deriving criteria weights, synthesizing decision elements, and ranking decision alternatives. A numerical example is used to clarify the method’s application
DUOPOLY MARKET COMPETITION OF PRICING AND SERVICE POLICIES UNDER A DUAL-SALE CHANNEL
No full textThe Internet provides lower company operating costs, increased product sales, understanding of customer preferences, and closeness to customers. Direct channels break barriers between suppliers and customers and change customer consumption patterns. However, they can also lead to competition and conflicts between upstream and downstream members of the supply chain. This study contributes to supply chain management research by investigating the joint impact of pricing policy, service-level investment, and dual-channel supply chain competition in a duopoly manufacturer channel. By simulating conditions similar to the actual market, the numerical experiment conducted in this study yielded several insights into the management of the dual-channel architecture. A targeted rebate mechanism is used to eliminate channel conflicts and persuade injured parties to accept the introduction of an online channel