Fuzzy logic application for extruders replacement problem

In a scenario of uncertainty and imprecision, before taking the replacement analysis, a manager needs to consider the uncertain reality of a problem. In this scenario, the fuzzy logic makes an excellent option. Therefore, it is necessary to make a decision based on the fuzzy model. This study is based on the comparison of two methodologies used in the problem of asset replacement. The study, thus, was based on a comparison between two extruders for polypropylene yarn bibliopegy, comparing mainly the costs involved in maintaining the equipment

Fuzzy logic application for extruders replacement problem

In a scenario of uncertainty and imprecision, before taking the replacement analysis, a manager needs to consider the uncertain reality of a problem. In this scenario, the fuzzy logic makes an excellent option. Therefore, it is necessary to make a decision based on the fuzzy model. This study is based on the comparison of two methodologies used in the problem of asset replacement. The study, thus, was based on a comparison between two extruders for polypropylene yarn bibliopegy, comparing mainly the costs involved in maintaining the equipment

The Proportionality Hypothesis in Capital Theory: an Assessment of the Literature

It  is  found  that  the  hypothesis  of  a  constant  replacement  investment  capital  stock  ratio  has several  fundamental  shortcomings.  It  conflicts  with  most  of  the  available  theoretical  and empirical evidence. It is alien to researchers in other fields of economics and related areas; and, perhaps most importantly, it has restrained progress in economic theory and econometric applications  based  on  more  realistic  conceptualizations  of  the  time  structure  of  capital.  On these grounds it is concluded that its abandonment is long overdue

Recursive expected conditional value at risk in the fleet renewal problem with alternative fuel vehicles.

We study the fleet portfolio management problem faced by a firm deciding which alternative fuel vehicles (AFVs) to choose for its fleet to minimise the weighted average of cost and risk, in a stochastic multi-period setting. We consider different types of technology and vehicles with heterogeneous capabilities. We propose a new time consistent recursive risk measure, the Recursive Expected Conditional Value at Risk (RECVaR), which we prove to be coherent. We then solve the problem for a large UK based company, reporting how the optimal policies are affected by risk aversion and by the clustering for each type of vehicle

The asset replacement problem state of the art.

This book chapter outlines the different modelling approaches for realising sustainable operations of asset replacement and studying the impact of the economic life, the repair-cost limit and comprehensive cost minimisation models. In particular it analyses in detail the parallel replacement models and suggests a new model that addresses some of the issues not yet solved in this area. Finally a discussion about the limitations of the current models from a theoretical and applied perspective is proposed and identifies some of the challenges still faced by academics and practitioners working on this topic

Developing an optimum maintenance policy by life cycle cost analysis - a case study

This paper focuses on developing maintenance policies for critical assets to improve the production performance based on life cycle cost (LCC) analysis. A general approach is adopted for conducting the LCC analysis. The investigation is based on a case study to demonstrate how an optimum maintenance policy is determined. The relevant LCC structure in the case study is defined for the decision process which involves determination of the optimum life, repair limit and selection of materials, and trade-off between repair and replacement. The LCC analysis is based on statistical data modelling which facilitates decision-making on the optimal replacement of an asset and its remaining life. Based on the optimization and remaining life criterion, the optimal maintenance policy can be made. The results obtained from this case study include selection of the best lining material for use, determination of the optimal time for refractory lining replacement, the hot repair sequence required for maintaining the optimum condition and the repair limit for doing cold repairs before replacement, for one type of electric arc furnaces used in the steel industry

A risk management system for sustainable fleet replacement.

This article analyzes the fleet management problem faced by a firm when deciding which vehicles to add to its fleet. Such a decision depends not only on the expected mileage and tasks to be assigned to the vehicle but also on the evolution of fuel and CO2 emission prices and on fuel efficiency. This article contributes to the literature on fleet replacement and sustainable operations by proposing a general decision support system for the fleet replacement problem using stochastic programming and conditional value at risk (CVaR) to account for uncertainty in the decision process. The article analyzes how the CVaR associated with different types of vehicle is affected by the parameters in the model by reporting on the results of a real-world case study

Exploring the Feasibility of Introducing Alternative Fuel Vehicles into Fleet

Transportation is one of the most significant contributing sectors to emissions and consequently air pollution in the United States. Many state and private fleet agencies have announced their visions of zero-emission fleet programs. Adopting alternative fuel vehicle (AFV) is a viable option for achieving this objective. AFVs offer lower emissions along with low operating and maintenance costs, and higher fuel economy. The advancement of technologies has provided several AFV options, such as hybrid electric vehicles (HEV), electric vehicles (EV), compressed natural gas vehicles (CNGV), and liquefied petroleum gas vehicles (LPGV). The main challenges in adopting AFVs are the high purchasing cost, lack of adequate infrastructure, and the uncertainty of future fuel cost. This study aims to introducing AFVs in the fleet while minimizing the life-cycle cost by utilizing an optimization replacement model. To account for the uncertainty of the fuel prices, the rolling horizon (RH) approach has been adopted for the optimization model. This RH approach considers the updated parameters and data while adjusting the vehicle replacement decisions. This study found purchasing price, variations of fuel price and daily activity (miles driven per day) of vehicles as the most significant factors for the vehicle replacement decisions. The study also showed that RH model can provide more cost-efficient fleet composition decisions compared to other models currently being used

Equipment replacement prioritization measures : simulation and testing for a vehicle fleet

Oregon Department of Transportation (ODOT) Fleet Services manages a fleet that in 2008 included approximately 5,000 pieces of active equipment worth $340–$390 million. Every biennium, a fixed budget is available to replace a certain amount of this equipment. This research evaluated various measures for establishing equipment replacement priorities. A model was developed to simulate the operation of a single equipment class over time, including equipment replacement every two years. Five different equipment classes were simulated using ten measures for establishing replacement priorities. Historical data for these five different equipment classes (provided by ODOT) was used to define various simulation parameters. The effectiveness of each prioritization measure was evaluated using the cost per mile to operate the fleet over the simulated time period