Reliability modelling and analysis of a two unit continuous casting plant

The aim of this paper is to present a reliability modeling and analysis of a two-unit system of a continuous casting (CC) plant. Real maintenance data of a steel production plant have been used for the purpose. Three types of failures were noted: repairable, replaceable and reconditioning/reinstallation. The two-unit system is operating in parallel, on full-reduced installed capacity. Upon the unit failure, an inspection is carried out to decide the type of maintenance task to be performed. Optimized reliability indices of the plant such as mean time to system failure, availability, expected busy periods of the repairman for various maintenance tasks, expected number of visits by the repairman, expected number of repairs, replacements and reconditioning/reinstallation are obtained. Semi-Markov processes and regenerative point techniques are used for the analysis. Profit incurred to the CC plant is also evaluated and related graphs are plotted to demonstrate the results.     

Exact analysis for the identification of non-minimum phase processes

Analytical expressions are derived from a single symmetrical relay feedback test for the identification of open loop stable and unstable non-minimum phase processes. The second derivative of the limit cycle output helps in finding the time delay of the process. The derived expressions can be used to identify the process models with up to five unknowns. The effectiveness of the proposed identification method is verified through different simulation results.     

New results on BIBO stability analysis for a class of neutral delay systems

This paper studies bounded input bounded output (BIBO) stability for a class of neutral systems with time-varying delays. Based on Lyapunov method and linear matrix inequalities, some new BIBO stability criteria are established. The numerical simulation is made to demonstrate the effectiveness of the theoretical results obtained in this paper.     

Is it a question of trust or why are we afraid to go to Nineveh?

Trust is an overused concept in our contemporary world. This paper explores the complex relationship of trust, efficiency, accountability, transparency and responsibility and their relationship to recordkeeping in our globalizing culture. It focuses on the profound changes that have taken place in the meaning and practice of audit within neo-liberal societies and how the ??rituals of verification?? and the ??managerialism?? may pervert the resulting record. It challenges the unthinking use of much of the rhetoric surrounding these concepts by archivists to justify their existence. It reflects on why the archival voice often remains silent or at best goes unheard in much of the discussion about these questions that have profound consequences for democratic societies. It is easy to lay the blame at the door of a perceived breakdown of trust rather than to consider whether the root of the problem lies with archivists and records managers themselves. This paper draws on my experience in directing the Information Management and Preservation MSC programme at the University of Glasgow and wide and serendipitous reading, which has sometimes been brought to my notice by students.     

VO2 prediction and cardiorespiratory responses during underwater treadmill exercise

We compared cardiorespiratory responses to exercise on an underwater treadmill (UTM) and land treadmill (LTM) and derived an equation to estimate oxygen consumption (VO2) during UTM exercise. Fifty-five men and women completed one LTM and five UTM exercise sessions on separate days. The UTM sessions consisted of chest-deep immersion, with 0, 25, 50, 75, and 100% water-jet resistance. All session treadmill velocities increased every 3 min from 53.6 to 187.8 m x min(-1). Cardiorespiratory responses were similar between LTM and UTM when jet resistance for UTM was 50%. Using multiple regression analysis, weight-relative VO2 could be estimated as: VO2 (mLO2 c kg(-1) x min(-1)) = 0.19248 x height (cm) + 0.17422 x jet resistance (% max) + 0.14092 x velocity (m x min(-1)) -0.12794 x weight (kg)-27.82849, R2 = .82. Our data indicate that similar LTM and UTM cardiorespiratory responses are achievable, and we provide a reasonable estimate of UTM VO2.     

The impact of different types of physical activity on total and regional bone mineral density in young Brazilian athletes

Bone turnover is affected by exercise throughout the lifespan, especially during childhood and adolescence. The objective of this study was to investigate the impact of different sports on total and regional bone mineral density in male Brazilian adolescent athletes. Forty-six adolescents aged 10-18 years participated in the study: 12 swimmers, 10 tennis players, 10 soccer players, and 14 sedentary individuals. The athletes had engaged in physical activities for more than 10 h per week in the previous 6 months. Bone mineral density of the lumbar spine (L1-L4), left proximal femur region, and whole body was evaluated by dual-energy X-ray absorptiometry. Results showed higher mean values in the proximal femur region of tennis and soccer players (1.02 ± 0.18; 0.96 ± 0.16, respectively) than swimmers and controls (0.91 ± 0.14 and 0.87 ± 0.06, respectively) (P < 0.05). In relation to the impact of sporting activities based on bone age determination, we observed significant differences in bone mineral density at all evaluated sites at the end of puberty (16-18 years) compared with 10-12 years, with increases of 78% in the lumbar spine, 47% in the proximal femur, and 38% in the whole body.     

Using clinical guidelines to assess the potential value of laboratory medicine in clinical decision-making

IntroductionIt is often quoted that 70% of clinical decisions are based on laboratory results, but the evidence to substantiate this claim is lacking. Since clinical guidelines aim to document best-practice decision making for specific disease conditions, inclusion of any laboratory test means that the best available evidence is recommending clinicians use it. Cardiovascular disease (CVD) is the world’s most common cause of mortality, so this study reviewed all CVD guidelines published by five national/international authorities to determine what proportion of them recommended laboratory testing.Materials and methodsFive leading CVD guidelines were examined, namely the European Society of Cardiology (ESC), the UK National Institute for Health and Clinical Excellence (NICE), the American College of Cardiology (ACC), the Australian Heart Foundation (AHF) and the Cardiac Society of Australia and New Zealand (CSANZ).ResultsA total of 101 guidelines were reviewed. Of the 33 individual ESC guidelines relating to CVD, 24/33 made a direct reference to the use of clinical laboratory tests in either diagnosis or follow-up treatment. The same applied to 15/20 of NICE guidelines, 24/32 from the ACC and 15/16 from the AHF/CSANZ. Renal function and blood count testing were the most recommended (39 and 26 times), with lipid, troponin and natriuretic peptide measurement advocated 25, 19 and 19 times respectively.ConclusionsThis study has shown that laboratory testing is advocated by between 73% and 94% of individual CVD guideline recommendations from five national/international authorities. This provides an index to assess the potential value of laboratory medicine to healthcare.     

Epidemiology in Middle School Science Curricula: a COVID-19 Pre–post Intervention

Journal of Science Education and Technology - It is of great importance that science educators teach COVID-19 and related pandemics to boost students’ scientific literacy. A mixed methods...