A fuzzy AHP multi-criteria decision-making approach applied to combined cooling, heating and power production systems

Most of the real-world multi-criteria decision-making (MCDM) problems contain a mixture of quantitative and qualitative criteria; therefore quantitative MCDM methods are inadequate for handling this type of decision problems. In this paper, a MCDM method based on the Fuzzy Sets Theory and on the Analytic Hierarchy Process (AHP) is proposed. This method incorporates a number of perspectives on how to approach the fuzzy MCDM problem, as follows: (1) combining quantitative and qualitative criteria (2) expressing criteria pair-wise comparison in linguistic terms and performance of the alternative on each criterion in linguistic terms or exact values when criterion is qualitative or quantitative, respectively, (3) converting all the assessments into trapezoidal fuzzy numbers, (4) using the difference minimization method to calculate the local weight of criteria, employing the algebraic operations of fuzzy numbers based on the concept of α-cuts, (4) calculating the global weight of criteria and the global performance of each alternative using geometric mean and the weighted sum, respectively, (5) using the centroid method to rank the alternatives. Finally, an illustrative example on evaluation of several combined cooling, heat and power production systems is used to demonstrate the effectiveness of the proposed methodology

A fuzzy multi-criteria decision making model for construction contractor prequalification

Selecting an appropriate contractor is essential for the success of any construction project. Contractor prequalification procedure makes it possible to admit for tendering only competent contractor. Prequalification is a multi-criteria decision problem that is, in essence, largely dependent on the uncertainty and vagueness in the nature of construction projects and subjective judgement of the decision-maker. This paper presents a systematic prequalification procedure, based on Fuzzy Set Theory, whose main differences and advantages in comparison with other models are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are used and the use of linguistic assessment or exact assessment of performance of the contractors on qualitative or quantitative criterion, respectively. Finally, a case study for the rehabilitation project of a building at Technical University of Cartagena is presented to illustrate the use of the proposed model and to demonstrate its effectiveness

Last planner control system applied to a chemical plant construction

The main difference between the Last Planner production control system developed by Ballard and classical control systems is the way in which projects are controlled and planned. The Last Planner system focuses on controlling production units, workflows and the quality of the performed work. It also permits the identification of the causes for the non-completion of planned work and decision making in accordance with the project requirements so that actions are timely and productivity is increased. The objective of this paper is to present the results obtained from implementing the Last Planner system in the construction department of a chemical company. In this department, an information flow problem was detected among its members, in which supervisors lacked knowledge about the work to be performed until the project had been perfectly designed. This problem often led to meant long delays in the projects. The results from Last Planner system implementation show that identifying the constraints of the planned work leads to an improvement in the percentage and quality of completed activitie

A fuzzy approach to construction project risk assessment

The increasing complexity and dynamism of construction projects have imposed substantial uncertainties and subjectivities in the risk analysis process. Most of the real-world risk analysis problems contain a mixture of quantitative and qualitative data; therefore quantitative risk assessment techniques are inadequate for prioritizing risks. This article presents a risk assessment methodology based on the Fuzzy Sets Theory, which is an effective tool to deal with subjective judgement, and on the Analytic Hierarchy Process (AHP), which is used to structure a large number of risks. The proposed methodology incorporates knowledge and experience acquired from many experts, since they carry out the risks identification and their structuring, and also the subjective judgements of the parameters which are considered to assess the overall risk factor: risk impact, risk probability and risk discrimination. All of these factors are expressed by qualitative scales which are defined by trapezoidal fuzzy numbers to capture the vagueness in the linguistic variables. The most notable differences with other fuzzy risk assessment methods are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are necessary, and the use of trapezoidal fuzzy numbers until the defuzzification step. An illustrative example on risk assessment of a rehabilitation project of a building is used to demonstrate the proposed methodology

Methodology for designing non-permanent living spaces for different areas in Castilla y León

[SPA] Los criterios de diseño de espacios de vida temporales están afectados directamente por el tiempo de despliegue de la instalación y no siempre esto se tiene en cuenta. Las infraestructuras temporales desplegadas en el ámbito militares deben tener en cuento criterios económicos y de retorno de la inversión en función de la temporalidad de dicho espacio desplegado en una zona, de esta manera, se optimizará la inversión de los recursos y se reducirá tanto el consumo energético como el transporte logístico de combustible en la zona, lo que provocará una disminución en los convoyes logísticos y por lo tanto una mayor seguridad e independencia energética. Para dar solución al análisis de la temporalidad se ha generado una metodología para el diseño de los parámetros de diseño de las paredes de los espacios de vida temporales.[ENG] The design criteria for temporary living spaces are directly affected by the deployment time of the facility and this is not always taken into account. Temporary infrastructures deployed in the military field must take into account economic criteria and return on investment based on the temporality of the space deployed in an area, thus optimising the investment of resources and reducing both energy consumption and the logistical transport of fuel in the area, which will lead to a reduction in logistical convoys and therefore greater security and energy independence. In order to provide a solution to the temporality analysis, a methodology has been generated for the design of the design parameters of the walls of the temporary living spaces

Real time test benchmark design for photovoltaic grid connected control systems

This paper presents a dual digital signal processor (DSP) hardware architecture for a grid-connected photovoltaic interface test benchmark, based on a cascade DC/DC converter and DC/AC inverter, with coordinated control algorithms. The control hardware has been designed to test distributed generation (DG) interfaces to be integrated in a hierarchical structure of computational agents, to apply distributed control techniques to the power system management. The proposed dual DSP architecture enables the programming of the control software for the DC/DC converter and the DC/AC inverter in the same processor, to keep the other one for additional operations that are required when there is a high degree of interaction between the DG unit and the rest of the electrical grid components. The hardware architecture has been tested in several real situations such as power factor correction and anti-islanding protection

Fuzzy multicriteria decision making applied to the strategic plan of Valencia

We present a fuzzy multicriteria decision making to get the ranking of several projects presented to the major council of Valencia whose final aim is to define the future urbanistic structure of the city This technique allows us to deal with such problems that are defined by linguistic (and vague)terms, like the case mentioned below