This is the second issue of the year 2014 and the International Journal of Performability Engineering (IJPE) enters the 10th year of its publication. We are often receiving queries from students, teachers expecting promotions, researchers and sometimes from librarians, particularly from India about the impact factor of IJPE. In this issue, for the benefit of our readers, we have explained on page 196 of this issue what does an impact factor signify? We also bring to our readers a note, on pages 234-236, on the visibility factor of IJPE which would inform our readers how IJPE has fared since its inception.in 2005. I must say here that we are not in competition with any other journal but we want to provide the best from the profession we are engaged in and I leave it to our readers to judge and assess the value of contributions that this journal has made to the scientific world over years after reading these two notes.
In this issue, we present 9 full papers and two short communications from diverse topics and areas of performability engineering. In the first paper of this issue, author presents a novel approach of structuring mission-critical systems with an emphasis on intrusion tolerance, recognizing the fact that it is virtually impossible today to completely prevent intrusion attacks from penetrating mission-critical systems, and efforts are being made on building intrusion tolerant systems. The second paper emphasizes the importance of reliability of a surveillance system to enhance the security level of a protected area breakdown of such system would leave the monitoring area unobserved and encountered much higher risk under the attacks. The paper provides a model which considers among other factors, the environment and skill of the intruder for predicting the reliability of such a system.
The third paper utilizes the powerful mathematical and statistical capabilities of Excel to propose a method of computing reliability of multi-phase mission system, which should be found useful by the reliability engineers. The fourth paper of the issue is from manufacturing area and illustrates the use of the robust deign technique to tackle some of the challenges and to establish it as a formal mechanism for ‘parameter design’ for carrying out machining operations efficiently in the job shops type of manufacturing firms. The technique is illustrated using a case study. The fifth paper suggests a special Monte Carlo algorithm based on importance sampling and extends the conventional network terminal connectivity criterion to develop a network reliability estimation methodology with unreliable nodes.
In the sixth paper, the authors present a probability voting strategy to combine several binary Support Vector Machines (SVMs) and then the multi-class SVMs are combined using majority voting strategy to obtain multi-class classifiers which is applied to the problem of fault diagnosis of gearbox. The seventh paper has an application from civil engineering area and demonstrates the use of Least Square Support Vector Machine (LSSVM) and Multivariate Adaptive Regression Spline (MARS), for determination of Uniaxial Compressive Strength of oporto granite which is a key parameter for determination of deformation behaviour of rock mass.
The eighth paper provides a method of monitoring of coast-down time (CDT) which is the time elapsed between the instant the power is switched off till the rotor system comes to rest. The paper demonstrates that, the CDT helps detect the defects of the shaft assembly. Experiments were conducted on a specifically fabricated rig. The authors define a parameter, called DIP that is found to correlate uniquely with the unbalance and the radial off-set defects in a shaft assembly. The ninth paper addresses the problem of managing availability requirements for systems that include prognostics and health management (PHM) strategies. PHM methods are incorporated into systems to avoid unanticipated failures that can potentially impact system safety and operation. Lastly, two short communications related to Grid computing and a Greenhouse Gas Baseline Emission Level Reporting System are included in this issue.
I like to thank all the authors, who have contributed to this issue with the assurance that we will continue to present various applications and aspects of performability engineering to various engineering disciplines and new research to our readers through this journal in the time to come.