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1811.

Scheduling stochastic two-machine flow shop problems to minimize expected makespan Pages 163-174 Download PDF

Authors: Mehdi Heydari, Mohammad Mahdavi Mazdeh, Mohammad Bayat

DOI: 10.5267/j.dsl.2013.04.005

Keywords: Expected makespan minimization, Flow shop scheduling, Stochastic flow shop, Stochastic scheduling

Abstract:

During the past few years, despite tremendous contribution on deterministic flow shop problem, there are only limited number of works dedicated on stochastic cases. This paper examines stochastic scheduling problems in two-machine flow shop environment for expected makespan minimization where processing times of jobs are normally distributed. Since jobs have stochastic processing times, to minimize the expected makespan, the expected sum of the second machine’s free times is minimized. In other words, by minimization waiting times for the second machine, it is possible to reach the minimum of the objective function. A mathematical method is proposed which utilizes the properties of the normal distributions. Furthermore, this method can be used as a heuristic method for other distributions, as long as the means and variances are available. The performance of the proposed method is explored using some numerical examples.

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1812.

A rolling horizon-based heuristic to solve a multi-level general lot sizing and scheduling problem with multiple machines (MLGLSP_MM) in job shop manufacturing system Pages 167-178 Download PDF

Authors: Mohammad Mohammadi, Omid Poursabzi

Keywords: Capacitated lot sizing and scheduling, Heuristic, Job shop, Rolling horizon approach, Sequence-dependent setup

Abstract:

This article addresses multi-level lot sizing and scheduling problem in capacitated, dynamic and deterministic cases of a job shop manufacturing system with sequence-dependent setup times and costs assumptions. A new mixed-integer programing (MIP) model with big bucket time approach is provided to the problem formulation. It is well known that the capacitated lot sizing and scheduling problem (CLSP) is NP-hard. The problem of this paper that it is an extent of the CLSP is even more complicated; consequently, it necessitates the use of approximated methods to solve this problem. Hence, two new mixed integer programming-based approaches with rolling horizon framework have been used to solve this model. To evaluate the performance of the proposed model and algorithms, some numerical experiments are conducted. The comparative results indicate the superiority of the second heuristic.

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1813.

An experimental investigation of HA/AL2O3 nanoparticles on mechanical properties of restoration materials Pages 173-182 Download PDF

Authors: Majid Safarabadi, Nabi Mehri Khansari, Abbas Rezaei

Keywords: Aluminum oxide, Hybrid Nano-composite, Hydroxyapatite, Mechanical properties, Polymethyl methacrylate

Abstract:

Nano composite materials based on polymers are widely used in restoration martials like dental. Poly methyl methacrylate (PMMA) is one of the most used polymers as dental material. PMMA has disadvantages such as low flexural strength properties and impact strength. In this paper, the influences of additive aluminum oxide and hydroxyapatite nanoparticles on the mechanical and strength properties of PMMA (including flexural strength, impact strength, surface hardness and shrinkage behavior) is studied experimentally. For this purpose, nine standard mechanical testing samples of pure PMMA, PMMA/5HA and PMMA/10HA with various amounts of Nano aluminum oxide (3,6,8 wt.%) were prepared. The results showed that the mechanical properties of hybrid Nano-composites were significantly improved in comparison with the pure samples in a way that optimal Nano-composite with convenience flexural properties and impact strength is obtained. Moreover, the use of nanoparticles results in shrinkage reduction of hybrid Nano-composites in comparison with pure PMMA.

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1814.

Forecasting stock price using grey-fuzzy technique and portfolio optimization by invasive weed optimization algorithm Pages 175-184 Download PDF

Authors: A. Hajnoori, M. Amiri, A. Alimi

DOI: 10.5267/j.dsl.2013.04.004

Keywords: Grey Fuzzy Technique, Invasive Weed Algorithm, Portfolio Optimization Model Cardinality Constrain, Prediction

Abstract:

Portfolio optimization problem follows the calculation of investment income per share, based on return and risk criteria. Since stock risk is achieved by calculating its return, which is itself computed based on stock price, it is essential to forecast the stock price, efficiently. In this paper, in order to predict the stock price, grey fuzzy technique with high efficiency is employed. The proposed study of this paper calculates the return and risk of each asset and portfolio optimization model is developed based on cardinality constraint and investment income per share. To solve the resulted model, Invasive Weed Optimization (IWO) algorithm is applied. In an example this algorithm is compared with other metaheuristic algorithms such as Imperialist Competitive Algorithm (ICA), Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The results show that the applied algorithm performs significantly better than other algorithms.

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1815.

Identifying the role of human resource management in increasing performance and implementation of six sigma projects using fuzzy cognitive maps Pages 179-190 Download PDF

Authors: Seyyed Yousef Oleyaei-Motlagh, Ali Bonyadi-Naeini

Keywords: Fuzzy Cognitive Maps, Human Resources Management, Project Management, Six Sigma

Abstract:

Six Sigma is known as the best quality management system, which has been applied in different places with distinct tasks. Any implementation of Six Sigma project normally can succeed only when human resource management is applied within the organization, properly. In this paper, we illustrate the intense of relationships between the human resources management indices and Six Sigma project implementation indices for some selected Iranian manufacturing firms. By using the fuzzy cognitive maps (FCM), we are able to show the strength of relationships among various indices. This study helps quality and human resource managers learn how to manage the critical indices to achieve their determined goals and to increase Six Sigma project performance throw human resource management perspective.

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1816.

Size and crack length effects on fracture toughness of polycrystalline graphite Pages 183-192 Download PDF

Authors: J. Akbardoost

Keywords: Crack length effect, Fracture toughness, Higher order terms, Modified maximum tangential stress criterion, Polycrystalline graphite, Size effect

Abstract:

In this paper, the effects of specimen size and crack length on the fracture toughness of polycrystalline graphite are studied. The experimental results reported in the previous studies showed that the fracture toughness of graphite increase in bigger specimen. It has been also demonstrated that the fracture toughness of graphite is nearly identical in specimens with crack length ratio less than 0.7 but decreases for grater crack length ratios. To justify the size and crack length dependency of fracture toughness, the modified form of maximum tangential stress (MMTS) criterion, which makes the use of higher order terms in calculating the stress field around the crack tip is employed. It is shown that the MMTS criterion can provide good estimates for the fracture toughness of graphite obtained from specimen with different sizes. It is also indicated that the MMTS criterion can predict very good the reported experimental fracture toughness data for samples with the crack length ratios less than 0.7.

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1817.

A multiple criteria decision making technique for supplier selection and inventory management strategy: A case of multi-product and multi-supplier problem Pages 185-190 Download PDF

Authors: Morteza Parhizkari, Maghsoud Amirib, Morteza Mousakhani

DOI: 10.5267/j.dsl.2013.04.003

Keywords: LP-Norm, Inventory management, NSGA-II, Supplier selection

Abstract:

Selection of an appropriate supplier along with planning a good inventory system has become an area of open research for the past few years. In this paper, we present a multi objective decision making supplier and inventory management model where two objectives including the quality and offering price of supplier are minimized, simultaneously. The proposed model is formulated as mixed integer programming and it is converted into an ordinary single objective function using Lp-Norm. In order to find efficient solution, we use NSGA-II as meta-heuristic technique and the performance of the proposed model is examined using some instances. The preliminary results indicate that both Lp-Norm and NSGA-II methods can be used to handle problems in various sizes.

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1818.

An investigation on the effects of business intelligence and enterprise resources planning on TQM Pages 191-198 Download PDF

Authors: Mehrdad Nouri Koupaei, Mohammad Mehdi Movahedi

Keywords: Business Intelligence, Enterprise Resource Planning, Smart Management, Total Quality Management

Abstract:

Nowadays Business Intelligence (BI) tools provide several decision support environment in enterprise systems like Enterprise Resource Planning (ERP) and they are mainly associated with computer-based techniques used in identifying, extracting and analyzing business data, such as sales revenue by products and/or departments, or by associated costs and incomes. The purpose of this paper is to provide a unified framework for the application of BI in ERP systems, which results in value-added quality control and management systems. In this paper, we expect to create business process automation and interaction between environment and technology by applying BI in ERP. Finally, a model is developed to represent the relationship between BI (as enabler of ERP) and the implementation of total quality management (TQM). The results indicate that using business intelligence, as an enabler of ERP, had good effect on achieving successful implementation of all three steps of Mukherjee model.

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1819.

Application of gray-based DEMATEL technique in designing of the aggregate green supply chain management’s model Pages 199-208 Download PDF

Authors: Adel Azar, Davood Andalib Ardakani

Keywords: Green Supply chain management, Grey-based DEMATEL Technique, Yazd Steel Industry

Abstract:

Nowadays, environmental issues are considered as the most important factor for competition. In this era, just modern companies can compete with each other and any environment friendly firm plays essential role in gaining more market share. Besides, the 21st century is the era of modern steel and Iranian iron steel industry plays important role in the domestic and international trade only through emphasizing on protection of environment. Therefore, designing a model for strengthening the environmental performance in steel industries is necessary to get some advantages such as energy saving, reducing pollutants, eliminating (declining) of waste, creating value for customers and improving the productivity. In this research, first, we explain green supply chain management and then grey-based DEMATEL Technique is used to identify different factors influencing the green supply chain. Eventually, the green supply chain model (GSCM) is applied for the steel industry. The result determines the most prominence factors of GSCM in Yazd Steel Industry.

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1820.

Experimental study on mechanical properties of different lightweight aggregate concretes Pages 201-208 Download PDF

Authors: S.M. Samareh Hashemi

Keywords: Compressive strength, Cost per metric volume, Lightweight aggregate concrete, Mixture density

Abstract:

Lightweight concrete is a suitable constructional material, which can decrease the weight of buildings and the hazards of earthquake loads. Hence, a large number of research studies have been focused on designing and manufacturing high strength lightweight concretes. In this research using the natural and industrial lightweight aggregates frequently found in the south-east region of Iran (Kerman province), high strength and low cost light weight concretes were manufactured. The effects of aggregate type, aggregate size, and concrete mixture were studied experimentally on the compressive strength of concretes and the density and cost of manufactured samples.

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