| || Quality and reliability of missile system
Author : Prahlada
Source : Defence Science Journal ; Vol:52(1) ; 2002 ; pp 5-10
Subject : 629.762 Missiles
Keywords : Missile systems;Reliability;weapon systems
Abstract : Missile system is a single-shot weapon system which requires very high quality and reliability. Therefore, quality and reliability have to be built into the system from designing to testing and evaluation. In this paper, the technological challenges encountered during development of operational missile system and the factors considered to build quality and reliability through the design, manufacture, assembly, testing and by sharing the knowledge with other aerospace agencies, industries and institutions, etc. have been presented.
| || Customer feedback system for continual quality improvement : A case study from Lakshya experiences
Author : Swami, Het Ram
Source : Defence Science Journal ; Vol:56(1) ; 2006 ; pp 71-80
Subject : 629.7 Aeronautics
Keywords : Customers feedback;Defect investigation;Quality improvement;Case study;Quality;Reliability;Lakshya;Unmanned aerial vehicle
Abstract : Customer's satisfaction is the measure of quality of a product or a service. Customers' feedback are important sources of product information on performance, improvements, and enhancement of ideas. The implementation of customer feedback system is essential to enhance the customers' satisfaction through continual improvement, which is essential for the survival of any organisation in a competitive environment. This study provides a structured approach to analyse and translate the customers' feedback into quality improvement of the product. The defects reported by the customers' on the unmanned aerial vehicle Lakshya systems were investigated while carrying out their rectification. Prompt remedial measures were also instituted to prevent their recurrence. This has resulted in the improvement of reliability and quality of the product. Finally, the implementation of customer feedback system and formalisation of defect investigation procedure for improving the quality and reliability of Lakshya systems has been described. A case study on Barco monitors (RGD 651) has also been demonstrated from Lakshya experience.
| || Optimising model for memory fault tolerance in onboard computer
Author : Mathew, Suresh V. ;Punnekkat, Saikumar ;Salam, Abdul
Source : Defence Science Journal ; Vol:52(1) ; 2002 ; pp 33-39
Subject : 629.7 Aeronautics;629 Transport Vehicle Engineering
Keywords : Reliability ;Fault tolerance ;Memory errors ;Onboard computers ;Real time systems
Abstract : This paper presents an optimising model for integrating the traditional reliability prediction methodology with simple analytical techniques to facilitate the designer to decide upon the memory fault-tolerant choices of an onboard computer. In this exercise, the hardware reliability estimates of a circuit without any error correction as well as that of a circuit with error detection and correction were calculated. The failure rates of each component and soldering have been accounted for in these prediction procedures. A suitable probability distribution is chosen for data errors and is analytically combined with the hardware reliability predictions to study the trade-offs. An optimum strategy for introducing the hardware error correction logic in the circuit is presented.
| || Quality management system : Some reflections
Author : Rao, Sudhakara K.
Source : Defence Science Journal ; Vol:56(1) ; 2006 ; pp 53-59
Subject : 629.7 Aeronautics;658 Management Sciences
Keywords : Quality management system;ISO 9000;Quality assurance;Reliability;Quality system;Fault tree analysis;FTA;QMS;Failure mode effects
Abstract : With the increasing demand for high quality products in every field, the demand for a good quality management system (QMS) in every organisation is increasing. This has since been well-appreciated by many organisations who have adopted QMS like ISO 9000, which has standardised the requirements for QMS. A well-organised QMS benefits the organisation in achieving its goals and sucess in its missions. In this paper, author's experiences in QMS and its implementation during his long tenure at ISRO, are briefly described. The author recalls a few incidents he faced during working on the projects of ISRO and DRDO, highlighting issues wrt quality and reliability, QMS, and ISO 9000 implementation. A few guidelines for effective QMS implementation are also suggested.
| || Minimisation of Non-periodic Preventive Maintenance Cost in Series-parallel Systems
Author : Wang, Chung-Ho;Lin, Te-Wei
Source : Defence Science Journal ; Vol:61(1) ; 2011 ; pp 44-50
Subject : 681.3 Computer Science
Keywords : Reliability;Preventive maintenance;Failure limit policy;Importance measure
Abstract : A new method to optimise the non-periodic preventive maintenance model of a series-parallel system is proposed. A two-stage algorithm that incorporates the failure limit policy to determine maintenance components, maintenance times, and total maintenance cost is suggested. When the reliability of the system reaches a threshold value, preventive maintenance is performed. The first stage identifies the parallel subsystem required to be maintained, while the second stage determines the component required to be maintained in the parallel sub-system. A unit-cost life index (UCL) has been developed to evaluate the extent to which maintaining a component extends the life of a system for the parallel subsystem. Three simulated cases demonstrate the effectiveness and the practicality of the proposed method in optimising the non-periodic preventive maintenance model of a series-parallel system.
| || Reliability, Availability, and Maintainability of Intermittently-used Repairable Systems
Author : Rajpal, P. S.;Shishodia, K. S.;Sekhon, G. S.
Source : Defence Science Journal ; Vol:57(2) ; 2007 ; pp 211-222
Subject : 532 Fluid Mechanics;53 Applied Physics
Keywords : Repairable system;Reliability;Weibull distribution;CMRAM;Transport helicopter;Simulation model;System reliability;System maintainability;Monte-Carlo simulation
Abstract : A composite measure comprising linear combination of reliability, availability, and maintainability (CMRAM) is proposed for an intermittently-used complex repairable system, namely a transport helicopter. The failure data are fitted in Weibull distribution for overlapping intervals of operating time to capture the effect of recent maintenance and other actions. Evaluation of CMRAM is helpful in formulating future operational and maintenance strategies.