The selection of a portfolio encounters several extremely complex situations. From among them, it has to be highlighted, due to its difficulty and transcendence, the Financial Assets selection when interrelations (positive and/or negative) occur among the expected profitabilities of each one of them. To solve this Genetic Algorithms are used due to its utility when offering solutions to complex...

In renewal processes, fuzziness and randomness often coexist intrinsically. Based on the random fuzzy theory, a delayed renewal process with random fuzzy interarrival times is proposed in this paper. Relations between the renewal number and interarrival times in such a process are investigated, and useful theorems such as the elementary renewal theorem, Blackwell renewal theorem and Smith key r...

Wireless sensor nodes can act as distributed detectors for recognizing activities online, with the final goal of assisting the users in their working environment. We propose an activity recognition architecture based on fuzzy logic, through which multiple nodes collaborate to produce a reliable recognition result from unreliable sensor data. As an extension to the regular fuzzy inference, we in...

Task scheduling is a main activity in the design of real-time systems (RTS). It assures both functionality and safety of such systems. RTS can be modeled as a set of periodic tasks that must be completed before speci/c deadlines. In this paper, we investigate the fuzzy scheduling models on RTS and the main methodologies that solve these models. Thus, we present general periodic task scheduling ...

By dealing with interarrival times as exponentially distributed fuzzy random variables, a fuzzy random homogeneous Poisson process and a fuzzy random compound Poisson process are respectively defined. Several theorems on the two processes are provided, respectively.

In this paper a new method based on fuzzy theory is developed to solve the project scheduling problem under fuzzy environment. Assuming that the duration of activities are trapezoidal fuzzy numbers (TFN), in this method we compute several project characteristics such as earliest times, latest times, and, slack times in term of TFN. In this method, we introduce a new approach which we call modif...

This paper presents a fuzzy approach to capacitated flow shop scheduling problem. Fuzzy sets are applied to express the flexible constraints on capacity of each period in the scheduling horizon. Fuzzy sets are also used to model the processing times of jobs and the setup times of machines required when a new job starts processing. Demand is set for each period. Over production incurs the holdin...

This paper considers a flow shop problem with imprecise processing times with the objective to minimize the makespan. The processing times are described by triangular fuzzy numbers. The issue that arises is how to rank the constructed job sequences with respect to their obtained makespans, which are fuzzy numbers. A new distance measure between fuzzy makespans is introduced which includes an op...

Activity networks have been used to model complex projects with wide applications in the field of production, planning and control. Stochastic activity networks (SANs) require a priori distribution function (d.f.) such as normal, exponential, Erlang and others. In this paper, a development of the moments method based on Weibull distribution of activity time is presented. The method provides an ...

In this paper, we investigate the existence of a positive solution of fully fuzzy linear equation systems where fuzzy coefficient matrix is a positive matrix. This paper mainly discusses a new decomposition of a nonsingular fuzzy matrix, a symmetric matrix times to a triangular (ST) decomposition. By this decomposition, every nonsingular fuzzy matrix can be represented as a product of a fuzzy s...