سال:1392 | دوره: | شماره: |تعداد مقالات:8

This paper represents linkage network of queues consisting of biserial and parallel servers linked to a common server in series with a flow shop scheduling system consisting of two machines. The significant transportation time of the jobs from one machine to another is also considered. Further, the completion time of jobs/customers (waiting time + service time) in the queue network is the setup time for the first machine. The objective of the paper is of two folds, on one hand it minimizes the total waiting time and service time of jobs/customers in the queue network, and on the other hand it minimizes the idle time of the machines for the optimal sequence of jobs/customers in a given queue flowshop linkage model. A computer programme followed by a numerical illustration is given to justify the proposed algorithm.

In this paper, we establish weak and strong duality theorems for a pair of multi-objective symmetric dual problems. This removes several omissions in the paper "Symmetric and self-duality in vector optimization problem, Applied Mathematics and Computation 183 (2006) 1121-1126".

Nowadays, in-flight comfort has become an essential characteristic to survive in domestic airline businesses. Air hostesses’ quality of service and response time to customer demand plays a vital role in enhancing quality of the flight experience and passenger satisfaction.  However, additional requirements on air hostess expose them to fatigue which could eventually result in job dissatisfaction also reflecting onto the customer.  This research studies the detailed tasks of airhostesses that take place from take-off to landing and answers such questions as usefulness of discrete-event simulation in assessing the performance measures of an airline hostess team and in improving them. Different activity scenarios are developed through simulation to provide a better organization of the multi-tasks that the airhostess provide to customers throughout the flight. This study is conducted on an airbus aircraft.

Scheduling is an enduring process where the existence of real time information frequently forces the review and modification of pre-established schedules. The real world is complex and complexity generally arises from uncertainty. From this prospective the concept of fuzziness is introduced in the field of scheduling. The present paper pertains to a bi-criterion in n-jobs, three machines flow shop scheduling to minimize the makespan and the rental cost of the machines taken on rent under a specified rental policy in which processing time, transportation time are in fuzzy environment and are represented by triangular fuzzy membership function. Further, the concept of job block to represent the relative importance of some jobs over other is also introduced. A heuristic algorithm to find optimal or near optimal sequence optimizing the bi-criteria is discussed. A numerical illustration is given to demonstrate the computational efficiency of proposed algorithm.

We propose a dynamic program to find the shortest path in a network having gamma probability distributions as arc lengths. Two operators of sum and comparison need to be adapted for the proposed dynamic program. Convolution approach is used to sum two gamma probability distributions being employed in the dynamic program.

Permanent Magnet Synchronous Motors (PMSMs) have been widely used in many industrial applications. In This paper a new method for multi-objective optimal design of a permanent magnet synchronous motor (PMSMs) with surface mounted permanent magnet rotor is presented to achieve maximum efficiency and power density using a Bees algorithm for industrial applications. The objective function is a combination of power density and efficiency to be maximized simultaneously. A particular optimal machine is chosen and its performances are validated with FE analysis. The design optimization results in a motor with great improvement regarding the original motor.

There are several systems in real situations that only accept a single and acceptable benchmark for efficiency improvement. For instance, when we are going to select a target for a country, the target country should be as close as the view of culture, economics and politics to the inefficient country. Otherwise, it would not be acceptable. Therefore, an inefficient country for several reasons can’t accept any efficient country for benchmarking. In this Paper we focus on this subject and show it in a real practical case.

In this paper, we propose a new concurrency control algorithm based on multi-agent systems which is an extension of majority protocol. Then, we suggest a clustering approach to get better results in reliability, decreasing message passing and algorithm’s runtime. Here, we consider n different transactions working on non-conflict data items. Considering execution efficiency of some different transactions simultaneously is one of our algorithm features. For evaluating performance of the proposed algorithm we applied it using the MPICH2 mechanism.