A study of postponed replacement in a delay time model

We develop a delay time model for a one component system with postponed replacement to analyze situations in which maintenance might not be executed immediately upon discovery of a defect in the system. Reasons for postponement are numerous: to avoid production disruption or unnecessary or ineffective replacement; to prepare for replacement; to extend component life; to wait for an opportunity. This paper explores conditions that make postponement cost-effective. We are interested in modelling the reality in which a maintainer either prioritizes functional continuity or is not confident of the inspection test indicating a defective state. In some cases more frequent inspection and a longer time limit for postponement are recommended to take advantage of maintenance opportunities, characterized by their low cost, arising after a positive inspection. However, when the cost of failure increases, a significant reduction in the time limit of postponement interval is observed. The examples reveal that both the time to defect arrival and delay time have a significant effect upon the cost-effectiveness of maintenance at the limit of postponement. Also, more simply, we find that opportunities must occur frequently enough and inspection should be a high quality procedure to risk postponement

Disability Pensions and Labor Supply

I investigate the incentive effects of disability pensions on the labor supply decision of the elderly in Germany. In the year 2001, a reform decreased the level of benefits and tightened the criteria of eligibility. The purpose of this paper is twofold: First, I estimate transition rates into disability retirement, both prior to and after the reform in order to evaluate the effect of the reform on retirement behavior. Second, I use the exogenous variation in (a) expected benefit levels and (b) expected benefit accruals that is caused by the reform, in order to obtain reliable estimates of individuals’ responses in retirement behavior to financial incentives. While health status and expected wages turn out to be important determinants of the decision to enter disability retirement, benefits have only a small effect.disability pensions, labor force exit, Germany

Pension Reform, Retirement and Life-Cycle Unemployment

The labor market effects of pension reform stem from retirement behavior and from job search and hours worked of prime age workers. This paper investigates the impact of four often proposed policy measures for sustainable pensions: strengthening the tax benefit link, moving from wage to price indexation of benefits, lengthening calculation periods, and introducing more actuarial fairness in pension assessment. We provide some analytical results and use a computational model to demonstrate the economic and welfare impact of recent pension reform in Austria.Pension Reform, Retirement, Job Search, Life-cycle Unemployment

Pension Reform, Retirement and Life-Cycle Unemployment

The labor market effects of pension reform stem from retirement behavior and from job search and hours worked of prime age workers. This paper investigates the impact of four often proposed policy measures for sustainable pensions: strengthening the tax benefit link, moving from wage to price indexation of benefits, lengthening calculation periods, and introducing more actuarial fairness in pension assessment. We provide some analytical results and use a computational model to demonstrate the economic and welfare impact of recent pension reform in Austria.pension reform, retirement, job search, life-cycle unemployment

Quantifying the Laffer Curve on the Continued Activity Tax in a Dynastic Framework

It is argued that the tax on continued activity should be removed by implementing actuariallyfair schemes. However, these schemes cannot fund the expected Social Security deficit. This paper proposes to give individuals a fraction of the actuarially-fair incentives in the case of postponed retirement. Social Security faces a trade-off between giving enough incentives to make individualselay retirement and giving little increase in pensions in order to help finance its expected deficit. This trade-off is captured by a Laffer curve. Finally, when the Social Security system aims to maximize welfare, the optimal tax on postponed retirement is still strictly positive.retirement behavior and wealth, actuarially-fair benefits.

"Double Dipping": The Combined Effects of Social Security and Civil Service Pensions on Employee Retirement

We consider the retirement behavior of civilian employees of the United States government. Unlike previous studies, this investigation is based upon a data set containing fairly complete and accurate information about the Social Security and employer-provided pensions for which employees are (or ultimately will be) eligible. These data permit us to specify the financial aspects of individual retirement decisions with a reasonable degree of precision. A large fraction of civil service pensioners is eligible to receive Social Security benefits because a part of their working careers was spent in Social-Security-covered employment. The prevalence of double pension coverage among government employees has raised serious equity questions about the treatment of civil servants by Social Security, and these questions have led to various suggestions for pension reform. Partly, the reform proposals have been put forward due to the perceived unfairness of "double dipping" which arises from the double pension coverage of government employees. Our analysis finds: (1) Both the amount of a Federal pension entitlement and the expected wait until the pension commences affect the timing of retirement from the Federal service. (2) The rate of anticipated wage growth significantly affects individual decisions to remain in Federal employment. (3) Workers who are eligible to ultimately receive Social Security in some cases show a different pattern of retirement than do workers not vested in Social Security. However, our analysis does not reveal any massive shift of Federal workers into Social-Security-covered employment in order to benefit from the "tilt" in the Social Security formula.

Social Security Rules and Labor Force Participation of Older Workers: Evidence from Chile

Recent research has argued that incentives stemming from social security systems influence the worker’s decision to retire. The experience of Chile, which radically changed its system in 1981, offers an opportunity to test this hypothesis. The new system tightened access to early pensions, replaced an actuarially unfair defined benefit plan with an actuarially fair defined contribution plan, exempted pensioners from the pension payroll tax and allowed widows to keep their own pension in addition to their survivor’s benefit. Although the old system is being phased out, since 1981 the two systems have co-existed. Using probit analysis of the behavior of a retrospective sample of new and old system affiliates, we estimate the impact of the new social security rules on the probability of dropping out of the labor force, for older workers. We find large effects. Age of pensioning has been postponed. Labor force participation is much higher among affiliates of the new system compared with the old, especially for pensioners and women. This is not simply due to selection: Aggregate participation rates have increased as the new system’s share of total affiliates has risen.

Delayed Participation of Developing Countries to Climate Agreements: Should Action in the EU and US be Postponed?

This paper analyses the cost implications for climate policy in developed countries if developing countries are unwilling to adopt measures to reduce their own GHG emissions. First, we assume that a 450 CO2 (550 CO2e) ppmv stabilisation target is to be achieved and that Non Annex1 (NA1) countries decide to delay their GHG emission reductions by 30 years. What would be the cost difference between this scenario and a case in which both developed and developing countries start reducing their emissions at the same time? Then, we look at a scenario in which the timing of developing countries’ participation is uncertain and again we compute the costs of climate policy in developed and developing countries. We findthat delayed participation of NA1 countries has a negative impact on climate policy costs. Economic inefficiencies can be as large as 10-25 TlnUSD. However, this additional cost wanes when developing countries are allowed to trade emission reductions from their baseline emission paths during the 30-year delay period. Thus, irrespective of whether NA1 countriesare immediately assigned an emission reduction target or not, they should nonetheless be included in a global carbon market. Technology deployment is also affected by the timing of developing countries’ mitigation measures. Delayed NA1-country participation in a climateagreement would scale down the deployment of coal with CCS throughout the century. Onthe other hand, innovation in the form of energy R&D investments would be positivelyaffected, since it would become crucial in developed countries. Finally, uncertainty about the timing of NA1-country participation does not modify the optimal abatement strategy for developed countries and does not alter policy costs as long as a global carbon market is in place.delayed action, climate policy, stabilisation costs, uncertain participation

Reducing branch delay to zero in pipelined processors

A mechanism to reduce the cost of branches in pipelined processors is described and evaluated. It is based on the use of multiple prefetch, early computation of the target address, delayed branch, and parallel execution of branches. The implementation of this mechanism using a branch target instruction memory is described. An analytical model of the performance of this implementation makes it possible to measure the efficiency of the mechanism with a very low computational cost. The model is used to determine the size of cache lines that maximizes the processor performance, to compare the performance of the mechanism with that of other schemes, and to analyze the performance of the mechanism with two alternative cache organizations.Peer ReviewedPostprint (published version

A Graph Rewriting Approach for Transformational Design of Digital Systems

Transformational design integrates design and verification. It combines “correctness by construction” and design creativity by the use of pre-proven behaviour preserving transformations as design steps. The formal aspects of this methodology are hidden in the transformations. A constraint is the availability of a design representation with a compositional formal semantics. Graph representations are useful design representations because of their visualisation of design information. In this paper graph rewriting theory, as developed in the last twenty years in mathematics, is shown to be a useful basis for a formal framework for transformational design. The semantic aspects of graphs which are no part of graph rewriting theory are included by the use of attributed graphs. The used attribute algebra, table algebra, is a relation algebra derived from database theory. The combination of graph rewriting, table algebra and transformational design is new