Particle Swarm Optimization and Maximum Entropy Results for MX/G/1 Retrial G-Queue with Delayed Repair

This paper examines an MX/G/1 retrial model with negative customers including the concepts of working vacation, Bernoulli feedback, delayed repair, state-dependent and multi-optional services. Such a queue is quite relevant in real world, for instance in computer systems, manufacturing organisations, packet-switching networks, telecommunication systems, etc. The arrival pattern of customers is according to Poisson distribution. The service is such that first essential service (FES) is provided to every customer and second optional service (SOS) is provided in k phases to those who wants to opt for the same. The negative customers may arrive during the time when the server is busy in serving a positive customer. This leads to breakdown of the server and thus the server has to be restored (repair) by the repair man. Some moments may be taken by the repair man to initiate the repair process, leading to delay in repair. In our work, firstly we have calculated performance measures like long run probabilities and orbit size along with some reliability indices. Then a relative study between the exact expected waiting time and approximate expected waiting time of the system is presented via maximum entropy approach. Also we perform cost optimization using particle swarm optimization (PSO method). Few numerical results are also provided.

An alternative approach in finding the stationary queue length distribution of a queueing system with negative customers

A single-server queueing system with negative customers is considered in this paper. One positive customer will be removed from the head of the queue if any negative customer is present. The distribution of the interarrival time for the positive customer is assumed to have a rate that tends to a constant as time t tends to infinity. An alternative approach will be proposed to derive a set of equations to find the stationary probabilities. The stationary probabilities will then be used to find the stationary queue length distribution. Numerical examples will be presented and compared to the results found using the analytical method and simulation procedure. The advantage of using the proposed alternative approach will be discussed in this paper.

Consumer perception towards sale of second-hand clothes in the localities of Odisha, States of India

Objective: The objective of this paper is to understand the perception of local people of Odisha specifically Bhubaneswar city towards the sale and purchase of second-hand clothes. This paper also highlights the importance of garment reuses for environmental benefits and how to promotion of the sale of second-hand garments. Methodology: The research methodology consisted of quantitative analysis from the data obtained through the distribution of questionnaires through online mode to the residents of Bhubaneswar city and a qualitative approach by interviewing them on their perception towards sale and purchase of second-hand clothes. Results: Consumers’ level of awareness regarding the implications of textile wastes on the environment is quite low. Perception of others on a customer purchasing second-hand clothes mattered a lot. Since that perception was mostly negative, customers always stepped back in making the purchase. Moreover, it was also associated with poor hygiene and quality which was a major turn off for them. Surprisingly, they didn't mind paying a good amount if the garment was good in quality & hygienic which is a positive sign as their mindset can be changed with a proper approach. Limitations: The survey was conducted with less sample size. Hence, more accurate and precise data can be obtained by increasing the sample size.

Customers’ reactions to different organizational tactics in a service termination context

Purpose This study aims to examine the effects of organizational tactics (e.g. explanation and monetary compensation) on customers’ reactions to service termination. The mediating role of anger and the moderating role of termination strategy on the effectiveness of organizational tactics are examined to enhance the understanding of customers’ reactions to service termination. Design/methodology/approach Three experimental studies are conducted with different contexts (telecom and banking) and samples (students and consumers). Findings Study 1 results show that explanation and high monetary compensation reduce negative word-of-mouth and enhance corporate image and anger mediates these effects. Study 2a results show that high monetary compensation becomes ineffective when firms use a soft termination approach. Study 2b results show that an explanation is equally effective in soft and hard termination approaches. Importantly, unlike high monetary compensation, the explanation can fully eliminate the negative consequences of service termination. Practical implications Managers can mitigate negative customers’ reactions to service termination by offering a truthful explanation. Further, they should provide high monetary compensation only if they do not help dismissed customers find an alternative provider. Originality/value This paper contributes to the service termination literature by shedding more light on the effectiveness of different organizational tactics following different termination strategies. The findings challenge existing wisdom on the overrated role of monetary compensation showing that in service termination, the explanation is the most effective remedy. Further, unlike justice, anger better explains customers’ reactions to service termination.

Numerical solution for the performance characteristics of the M/M/C/K retrial queue with negative customers and exponential abandonments by using value extrapolation method

This paper deals with a retrial queueing system M/M/C/K with exponential abandonment at which positive and negative primary customers arrive according to Poisson processes. This model is of practical interest: it permits to analyze the performance in call centers or multiprocessor computer systems. For model under study, we find the ergodicity condition and also the approximate solution by applying Value Extrapolation method which includes solving of some algebraic system of equations. To this end, we have resolved the algebraic system in question by different numerical methods. We present also numerical results to analyze the system performance.

EQUILIBRIUM BALKING STRATEGIES IN THE REPAIRABLE M/M/1 G-RETRIAL QUEUE WITH COMPLETE REMOVALS

We consider an M/M/1 retrial queue subject to negative customers (called as G-retrial queue). The arrival of a negative customer forces all positive customers to leave the system and causes the server to fail. At a failure instant, the server is sent to be repaired immediately. Based on a natural reward-cost structure, all arriving positive customers decide whether to join the orbit or balk when they find the server is busy. All positive customers are selfish and want to maximize their own net benefit. Therefore, this system can be modeled as a symmetric noncooperative game among positive customers and the fundamental problem is to identify the Nash equilibrium balking strategy, which is a stable strategy in the sense that if all positive customers agree to follow it no one can benefit by deviating from it, that is, it is a strategy that is the best response against itself. In this paper, by using queueing theory and game theory, the Nash equilibrium mixed strategy in unobservable case and the Nash equilibrium pure strategy in observable case are considered. We also present some numerical examples to demonstrate the effect of the information together with some parameters on the equilibrium behaviors.

Analysis of G-network with unreliable service systems

In this paper, the object of research is Markov’s network with positive and negative customers and unreliable service lines with single-line queuing systems (QS). The discipline of service of customers in the systems – FIFO (“first come first served”) and the service time of customers in each line of the QS network are distributed according to the exponential law with their parameters for each QS. The service lines in each QS are defeated by accidental breakdowns, and the time of correct operation of the service line in each SMO has an exponential distribution, with different parameters for each QS. After the breakdown, the line immediately begins to recover, and the recovery time also has an exponential distribution, the parameters of which are different for each QS. The aim of the study is to find the non-stationary probabilities of network states. To find them, a modified method of successive approximations combined with the method of series is proposed. This method allows one to remove the condition of high load. The properties of successive approximations are proved. On the basis of the obtained data, using a computer, a model example illustrating the finding of the time-dependent probabilities of network states is calculated. The results of this work can be applied to the modeling of various information systems and networks.