Optimal Burn-in Time and Imperfect Maintenance Strategy for a Warranted Product with Bathtub Shaped Failure Rate

‘Burn-in/preventive maintenance’ programme is an efficient approach used to minimise the warranty servicing cost of a product with bathtub shaped failure rate. Burn-in is a widely used method to improve the quality of product during its ‘infant mortality’ period and preventive maintenance is a scheduled necessary activity carried out during its ‘wear-out’ period. In this paper, an optimisation model is developed to determine the optimal burn-in time and optimal imperfect preventive maintenance strategy that minimises the total mean servicing cost of a warranted product with an age-dependent repair cost. We provide a numerical study to illustrate our results

The effect of reliability improvement actions and providing warranty policy type LIC and FRW/LSW on price range of used devices

Access to new products and also buyers’ requirements to specific technologies have become more difficult because of the low purchasing power of some consumers, some sanctions and political issues in the world; these cases have caused noticing to second- hand market. Product warranty and performance guarantee are also the cases to attract customer and gain his/her trust. Buyers’ hesitant on proper functioning of these products has encouraged vendors to perform reliability improvement actions and provide valid warranties to gain their confidence. The effect of reliability improvement actions and providing warranty policies limited on individual cost (LIC) and free replacement warranty /repair warranty/lump sum warranty (FRW/LSW) on the price range of two types of used laboratory equipments of Mehr Abrar Company will be surveyed. This research is an applicable type that after consistency of failure rate function with exponential function has been used for estimation of warranty cost from available models in the literature. Warranty cost was also calculated after reliability improvement actions with hybrid approach of virtual life, minor-full repair; and then determined by using cost data of accounting department in price range of each device. Statistical society consists of all failure data of cell counter and biochemistry devices of Mehr Abrar Company in the period of four years.The results show that after performing reliability improvement actions, period warranty costs are reduced; and this affects on total costs and devices price per unit. For vendor, the cost of LIC policy is more than FRW/LSW warranty, this is because that a higher price ceiling has been considered. However, FRW/LSW policy in long-term and LIC policy in short-term can help the vendor to provide his/her product

Modeling and Solving Flow Shop Scheduling Problem Considering Worker Resource

In this paper, an uninterrupted hybrid flow scheduling problem is modeled under uncertainty conditions. Due to the uncertainty of processing time in workshops, fuzzy programming method has been used to control the parameters of processing time and preparation time. In the proposed model, there are several jobs that must be processed by machines and workers, respectively. The main purpose of the proposed model is to determine the correct sequence of operations and assign operations to each machine and each worker at each stage, so that the total completion time (Cmax) is minimized. Also this paper, fuzzy programming method is used for control unspecified parameter has been used from GAMS software to solve sample problems. The results of problem solving in small and medium dimensions show that with increasing uncertainty, the amount of processing time and consequently the completion time increases. Increases from the whole work. On the other hand, with the increase in the number of machines and workers in each stage due to the high efficiency of the machines, the completion time of all works has decreased. Innovations in this paper include uninterrupted hybrid flow storage scheduling with respect to fuzzy processing time and preparation time in addition to payment time. The allocation of workers and machines to jobs is another innovation of this article

Developing a Trade-off between Upgrade Action Time and Warranty Length for Second-hand Electrical Components

One way of improving the reliability and reducing the warranty servicing cost for second-hand items is through actions such as overhaul and upgrade which are carried out by the dealer or a third party. For second-hand electrical components, the improvement involves testing of items for a short time, called upgrade action time, before their release to the market. The items that fail during the test are scrapped or repaired; only items that survive the test are considered to be of good quality and released to the market. In this paper, a cost model is developed to achieve a trade-off between reducing the warranty servicing cost and increasing the upgrade action cost for a second-hand electrical component sold under various warranty policies

Identification and Ranking the Implementation Barriers of TPM Using Fuzzy AHP: A Case Study of Gas Industry in Iran

Total Productive Maintenance or TPM is a philosophy to enhance an organization’s productivity and produce high quality goods by minimizing waste thereby reducing costs. TPM is designed to maximize equipment efficiency by determining an extensive productive maintenance system covering the whole life of the equipment, extending across all equipment-related fields and with participation of all employees from the top management to the shop-floor workers, to advance productive maintenance through voluntary small group activities (Tsuchiya 1992). Most of the automotive manufacturing industries are focusing on strict quality standards in their production process and implementing a quality program called Total Productive Maintenance. With the fast development of the maintenance, it becomes critical to set up a TPM Evaluation criteria system. Fuzzy Analytic Hierarchy Process is a new multi-criteria evaluation method evolved from Saaty's AHP. So, this paper aimed to find out and rank the key factors and obstacles that affect success in TPM in Gas industry using fuzzy AHP approach, and give an evaluation method for TPM in order to help researches and managers to determine the drawbacks and opportunities

Storia della repubblica di Venezia dalla sua fondazione sino l'anno 1747. Di Giacomo Diedo senatore proseguita da dotta penna fino all'anno 1792 - vol. 6

1792 Segn.: A-T8. // Buchi di tarlo fino a c. 8A http://catalogo.unipd.it/F?func=find-c&ccl_term=IDN=TSAE001915&local_base=SBP0

Developing a Balanced Scorecard Model for LARG Supply Chain Evaluation: A Dynamic Approach

Purpose – Organization managers tend to use an optimal and precise method to evaluate the performance of their organization by understanding the organization dynamics. The immediate research goal was to propose a dynamic model for the performance evaluation of a LARG supply chain with the balanced scorecard (BSC) approach. Design/methodology/approach – In this study, dynamic simulations are carried out for the performance evaluation of a supply chain. At first, a strategy map was designed, and measures are identified for each strategic objective considering the LARG supply chain measures. Afterward, a quantitative dynamic model was designed to identify the mathematical relationships among them. Findings – The proposed model is implemented in a company operating in the automotive industry. Based on the company’s strategic objectives, scenarios were designed and analyzed to evaluate the performance of the LARG supply chain with the balanced scorecard approach. Research limitations/implications – The BSC- based LARG supply chain evaluation has been studied for the auto part manufacturer sector. The different industry may lead to different results as the model designed important in each sector may differ as well as how each model is designed.Originality/value – The dynamic model enables managers to identify the determinants of the supply chain performance and set the scene for the necessary decisions by analyzing the possible scenarios in advance

A Novel Travel Time Estimation Model for Modeling a Green Time-Dependent Vehicle Routing Problem in Food Supply Chain

In a green time-dependent vehicle routing optimisation problem, if the travel time is not well estimated, the values of the objective function (emissions) for different solutions will be obtained with less accuracy, which leads to wrong decision making. The purpose of this paper is to propose an accurate travel-time estimation model. The model was developed by considering the different multiple traffic modes through a continuous approach. Moreover, in this model, it was assumed that the route between two nodes was a combination of different segments (i.e., expressway, boulevard, main street, auxiliary street, alley, etc.), and the speed level varied along the route and depended on the segments of the route. Congestion is a key factor affecting the delivery time of food to customers. To assess the reliability of the model, data from the delivery and sales network of the oldest and biggest beverage manufacturer in Iran was used. A new congestion pattern was identified based on the analysis of 272 routes and several rules were described that proved the above assumption about congestion. The travel time estimated for 30 random vehicles with random departure times were compared with data from Google Maps through statistical analyses