Volume 13, Number 1, January 2017 - Editorial - p 1
Vallayil N.A. Naikan
This is the first issue of the year 2017 and it is also the last issue under my editorship of International Journal of Performability Engineering which was being published for last 12 years. Dr. Dianxiang Xu and myself have been the Co-Editors-in-Chief of the Journal during the year 2016. From January 01, 2017, the journal will have two new Co-Editors-in-Chief, namely, Professor S. K. Chaturvedi, Reliability Engineering Center at IIT Kharagpur, India (email@example.com / firstname.lastname@example.org) and Dr. Suprasad V. Amari, BAE Systems, USA. (Suprasad.email@example.com). Professor Xing (Email: firstname.lastname@example.org) will remain the Editor for Short Communications in 2017.
Formal introduction of the new Co-Editors-in-Chief and the Editor for Short Communications is presented on the next page of this issue (page 2). The Editorial Board remains unchanged. I am sure the IJPE would continue to flourish under the leadership of these people and will be printed and published timely with excellence in the years to come. I wish the new Editorial team of IJPE and the IJPE unprecedented success in fulfilling the tasks that are on the anvil and take great strides towards the success of unfinished tasks connected with the objectives for which the International Journal of Performability Engineering was launched in July 2005.
This issue consists of eight papers from different areas of performability engineering. In the first paper, the performance effect of fluid flow inside the centralized waste collection pipeline is numerically investigated with different configuration of inlet points which were opened at the same time of discharge.
The second paper aims to reduce process variation of Chopped Strand Mat (CSM) in a fiber industry in the state of Goa, India. Critical process parameters have been identified using brainstorming and multi-voting method. Taguchi method of experimental design has been used to identify key factors and their optimal levels. Reduction of variance coupled with an economic analysis has been carried out and reported in the paper.
The third paper discusses the issue of integrated planning of maintenance activities and production operations at the tactical level for multi-line systems with separate resources and introduces the breaking on demand constraint and that of setup time. The paper also presents a numerical example to illustrate the results and represent the economic gap between the separate and integrated planning.
In the fourth paper, the Bayesian and classical estimation of augmented strength reliability under Augmentation Strategy Plan (ASP) have been considered. A comparative study between Maximum Likelihood and Bayesian estimators have been carried out on the basis of mean square errors (MSE) and absolute biases. The Markov Chain Monte Carlo method of approximations has been applied to draw posterior expectations under both the loss functions. The MSE and absolute biases are calculated with 1000 replications.
The fifth paper presents a discrete state space and continuous time stochastic model for two unit hot standby database system. The primary unit is production unit synchronized with hot standby unit through online transfer of archive redo log files. Different modes of failure of primary database unit are considered. Expressions for various measures of system effectiveness have been obtained by making use of semi-Markov processes and regenerative point technique.
The focus of the sixth paper is related to application of Digimat-FE to generate a realistic three dimensional microstructure for the current carbon nanotube/ epoxy composite and carried FEA to estimate the effect of nanotube dimensions on the elastic properties. Analysis shows that nanocomposite elastic properties were found to be particularly sensitive to the nanotube diameter, since larger diameter nanotubes showed a lower effective modulus and occupied a greater volume fraction in the composite relative to smaller-diameter nanotubes.
In the seventh paper, additional fault frequency features in vibration spectrum have been proposed to detect the presence of single broken rotor bar (BRB) fault in VFD driven induction motors. The additional fault frequencies are identified in the vicinity of carrier frequency of the VFD drive for effective fault diagnosis. The proposed additional frequency features will be useful to correctly identify the BRB faults at low load and no load conditions, which was very difficult using the presently available fault frequencies in the literature.
The last paper proposes a two-step method for damage bar detection in tower structures. The damage units are identified from cross-correlation function and second generation wavelets of vibration signals collected from the structure. SVM is carried for pin pointing damage bar location.