In this research, we study an optimal overhaul–replacement policy of a multi-degraded repairable system sold with a free replacement warranty. In the proposed replacement policy, a maintenance action and failure are dependent on a system degradation level and the system age, and hence the replacement model will provide more effective maintenance decisions. Failure of the system is modeled using...

INTRODUCTION Being a unique diagnostic technique, transesophageal echocardiography (TEE) has influenced many different aspects of cardiac surgery including valve repair surgery. The cost-effectiveness of this method however is questioned considering the conditions of every region and country. In this study we aimed at answering the question if utilizing TEE throughout valve repair surgery could...

The parallel machine replacement problem consists of finding a minimum cost replacement policy for a finite population of economically interdependent machines. In this paper, we formulate a stochastic version of the problem and analyze the structure of optimal policies under general classes of replacement cost functions. We prove that for problems with arbitrary cost functions, there can be opt...

this project was conducted to evaluation the effects of replacement of barley grain with corn grain on fatteningperformance of male lambs. twenty five male lambs (6-7 month-old, average body weight = 31.22 ± 3.4 kg) were assigned randomly to five dietary treatments (5 lambs/treatment) in a randomized complete design. the first diet contained barley grain without corn grain but in the other diet...

AIM To establish whether universal vaccination of infants with the pneumococcal conjugate vaccine is likely to be cost-effective from the perspective of the health care provider (NHS). METHOD Two hypothetical cohorts--one vaccinated and one unvaccinated--were followed over their lifetime, and the expected net costs and benefits (measured in terms of life-years and quality adjusted life years ...

This thesis develops integer linear programming models for and studies the complexity of problems in the areas of maintenance optimization and location–routing. We study how well the polyhedra defined by the linear programming relaxation of the models approximate the convex hull of the integer feasible solutions. Four of the papers consider a series of maintenance decision problems whereas the ...

adsorption is a fundamental process in the physicochemical treatment of wastewaters which industries employ to reduce hazardous organic and inorganic wastes in effluents. in recent years the use of low-cost adsorbents has been widely investigated as a replacement for the currently costly methods of removing heavy metal ions from wastewater. it is well-known that cellulosic waste materials can b...

introduction: in this study, arrangement of a low-cost optical tomography device compared to other methods such as frequency domain diffuse tomography or time domain diffuse tomography is reported. this low-cost diffuse optical imaging technique is based on the detection of light after propagation in tissue. these detected signals are applied to predict the location of in-homogeneities inside p...

BACKGROUND Treatment with trisodium citrate provides an effective means of regional anticoagulation during continuous renal replacement therapy (CRRT). We evaluated the efficacy, safety and cost of a regional citrate anticoagulation protocol using commercial solutions in 17 critically ill patients treated with continuous venovenous haemodiafiltration (CVVHDF). We performed a total of 22 session...

Patients with symptomatic aortic stenosis have a poor prognosis, and medical therapy has little, if any, effect on their natural history. Surgical aortic valve replacement (AVR) is risky, yet it appears to be effective in extending life expectancy and reducing symptoms due to aortic stenosis. In this setting, the development of transcatheter AVR appears to be a breakthrough technology, potentia...