Optimising Age-Replacement and Extended Non-Renewing Warranty Policies in Lifecycle Costing

This paper analyses the life cycle cost of equipment protected by both base and extended warranty policies from a consumer's perspective. We assume that the equipment has two types of failure: minor and catastrophic. A minor failure can be corrected with minimal repair whereas a catastrophic failure can only be removed by a replacement. It is assumed that equipment is maintained at no charge to the consumer during the warranty period, whereas the consumer is fully charged for any maintenance on failures after the extended warranty expires. We formulate the expected life cycle cost of the equipment under a general failure time distribution, and then for special cases we prove that the optimal replacement and extended warranty policies exists where the expected life cycle cost per unit time is minimised. This is examined with numerical examples. © 2011 Elsevier B.V. All rights reserved

Estimation of component redundancy in optimal age maintenance

The classical Optimal Age-Replacement defines the maintenance strategy based on the equipment failure consequences. For severe consequences an early equipment replacement is recommended. For minor consequences the repair after failure is proposed. One way of reducing the failure consequences is the use of redundancies, especially if the equipment failure rate is decreasing over time, since in this case the preventive replacement does not reduce the risk of failure. The estimation of an active component redundancy degree is very important in order to minimize the life-cycle cost. If it is possible to make these estimations in the early phase of system design, the implementation is easier and the amortization faster. This work proposes an adaptation of the Optimal Age-Replacement method in order to simultaneously optimize the equipment redundancy allocation and the maintenance plan. The main goal is to provide a simple methodology, requiring the fewer data possible. A set of examples are presented illustrating that this methodology covers a wide variety of operating conditions. The optimization of the number of repairs between each replacement, in the cases of imperfect repairs, is another feature of this methodology

Independent Orbiter Assessment (IOA): Analysis of the crew equipment subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical (PCIs) items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results coresponding to the Orbiter crew equipment hardware are documented. The IOA analysis process utilized available crew equipment hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 352 failure modes analyzed, 78 were determined to be PCIs

Airborne Communications in Operation Market Garden

Operation Market Garden, Field Marshal B.L.M. Montgomery’s grand attempt to end the war in 1944, has been ceaselessly analysed in an attempt to understand the reasons for its failure. Factors such as the distance of the drop zones from the objectives in Arnhem, the delay in resupply, the presence of strong German forces in the area, as well as the slow progress of XXX Corps in linking the airborne bridgeheads, are some of the main reasons cited for the failure of the operation. Another element often raised has to do with the failure of communications equipment at Arnhem. Peter Harclerode, in his book, Arnhem: A Tragedy of Errors, puts it bluntly: “Much of the blame for 1st Airborne Division’s demise has been laid at the door of signals failure as well as the unsuitability of radio equipment issued to the division as well as its failure to work satisfactorily under the condition in which it was employed.” Lewis Golden, the adjutant of Divisional Signals during the operation argues that this was not the case. Signals actually worked better than could be expected and that communications failure was not the principal reason for defeat at Arnhem. This article attempts a comprehensive survey of the role of communications and answers the question, “How far were poor communications responsible for the failure of Market Garden?” In particular, how far did poor communications contribute to the failure of 1st Airborne Division to consolidate a bridgehead at the Arnhem road bridge

A system for early warning of bearing failure

System for detecting incipient failure in ball bearings is described. Ultrasonic equipment detects bearing system resonance and provides warning signal through electronic circuitry. Detector can be used to evaluate performance of newly installed bearings. Schematic diagram is provided to show components

Application of a truncated normal failure distribution in reliability testing

Statistical truncated normal distribution function is applied as a time-to-failure distribution function in equipment reliability estimations. Age-dependent characteristics of the truncated function provide a basis for formulating a system of high-reliability testing that effectively merges statistical, engineering, and cost considerations

Critical Equipment Identification Approach for Condition-Based Maintenance Planning in a Beverage Plant

A critical equipment identification approach for condition-based maintenance (CBM) planning in the beverage plant is presented. In this study, critical equipment in a beverage industry was identified for effective condition based maintenance planning. The approach involves multiplying four generic factors namely; probability of failure, losses in in-process materials, mean-time-to-repair (MTTR) and mean cost of repairs. The score for the probability of failure was estimated as a function of cumulative failure rate (CFR) of respective plant equipment. Four grades of equipment failure probability were used: very low probability of failure, low probability of failure, medium probability of failure and high probability of failure. MTTR was determined from the identified probability distribution described by the repair data of the reference equipment. Losses in in-process materials were computed from a comparison of the total throughput and the lost brews. The results show that the Dust aspirator, Weighing bin, Mash filter and Chain conveyors with average criticality index of 0.2712, 0.2199, 0.1350 and 0.1563 respectively, are the most critical equipment in a beverage plant. This implies that planning and control of maintenance on the identified critical equipment based on condition monitoring will help improve the production efficiency in the brewing process. Keywords: Critical equipment, Condition based maintenance, Cumulative failure rate, Mean time to repair, Mean cost of repair

Mandatory Vote Count Audit

Voters, candidates, citizens and election officials want high confidence in the integrity of the election process by subjecting electronic vote counts to independent manual audits; and by making reports available with which to evaluate rates of voter turnout, voting equipment allocation, under-votes, over-votes, spoiled ballots, voting equipment failure, absentee ballots, uncounted ballots, and provisional ballots. This bill requires routine independent audits of vote count accuracy and requires the release to vote count auditors of records and information necessary to verify the integrity of the vote count audits and to evaluate voter service levels