Using Fluid Curtains to Improve Sealing Performance in Turbomachinery Applications

The results from an investigation into the physics of how fluid curtains can be applied to improve the aerodynamic performance of conventional turbomachinery shaft and rotor seals are described in this paper. Computational fluid dynamics and testing on two experimental facilities are used in the study. In the first part of the work, computational fluid dynamics simulations validated against experimental test data demonstrate the fundamental mechanism by which the presence of the curtain can act to reduce leakage flow through conventional seals. These results are consolidated into a single performance carpet map, showing how the leakage reduction performance and the curtain supply pressure needed to achieve it vary with changes in values of key geometrical parameters. In the second part of the work the effect of swirl in the seal inlet flow, as is often encountered in turbomachinery applications, on the performance of the fluid curtain is investigated experimentally. Test results show that if the swirl momentum in the inlet flow is greater than the momentum of the curtain flow, the performance benefit from applying the curtain is greatly diminished. Overall, the results provide some fundamental design rules for applying fluid curtains to enhance turbomachinery sealing performance for the general type of leakage path geometry (cylindrical channel, 45-degree jet angle, curtain upstream of a conventional seal) and working fluid type and conditions (air, ambient temperature, subsonic leakage channel flow), used in the study

Occupational cancer in Britain: Exposure assessment methodology

To estimate the current occupational cancer burden due to past exposures in Britain, estimates of the number of exposed workers at different levels are required, as well as risk estimates of cancer due to the exposures. This paper describes the methods and results for estimating the historical exposures. All occupational carcinogens or exposure circumstances classified by the International Agency for Research on Cancer as definite or probable human carcinogens and potentially to be found in British workplaces over the past 20–40 years were included in this study. Estimates of the number of people exposed by industrial sector were based predominantly on two sources of data, the CARcinogen EXposure (CAREX) database and the UK Labour Force Survey. Where possible, multiple and overlapping exposures were taken into account. Dose–response risk estimates were generally not available in the epidemiological literature for the cancer–exposure pairs in this study, and none of the sources available for obtaining the numbers exposed provided data by different levels of exposure. Industrial sectors were therefore assigned using expert judgement to ‘higher'- and ‘lower'-exposure groups based on the similarity of exposure to the population in the key epidemiological studies from which risk estimates had been selected. Estimates of historical exposure prevalence were obtained for 41 carcinogens or occupational circumstances. These include exposures to chemicals and metals, combustion products, other mixtures or groups of chemicals, mineral and biological dusts, physical agents and work patterns, as well as occupations and industries that have been associated with increased risk of cancer, but for which the causative agents are unknown. There were more than half a million workers exposed to each of six carcinogens (radon, solar radiation, crystalline silica, mineral oils, non-arsenical insecticides and 2,3,7,8-tetrachlorodibenzo-p-dioxin); other agents to which a large number of workers are exposed included benzene, diesel engine exhaust and environmental tobacco smoke. The study has highlighted several industrial sectors with large proportions of workers potentially exposed to multiple carcinogens. The relevant available data have been used to generate estimates of the prevalence of past exposure to occupational carcinogens to enable the occupational cancer burden in Britain to be estimated. These data are considered adequate for the present purpose, but new data on the prevalence and intensity of current occupational exposure to carcinogens should be collected to ensure that future policy decisions be based on reliable evidence

A mechanistic spatio-temporal framework for modelling individual-to-individual transmission—With an application to the 2014-2015 West Africa Ebola outbreak

In recent years there has been growing availability of individual-level spatio-temporal disease data, particularly due to the use of modern communicating devices with GPS tracking functionality. These detailed data have been proven useful for inferring disease transmission to a more refined level than previously. However, there remains a lack of statistically sound frameworks to model the underlying transmission dynamic in a mechanistic manner. Such a development is particularly crucial for enabling a general epidemic predictive framework at the individual level. In this paper we propose a new statistical framework for mechanistically modelling individual-to-individual disease transmission in a landscape with heterogeneous population density. Our methodology is first tested using simulated datasets, validating our inferential machinery. The methodology is subsequently applied to data that describes a regional Ebola outbreak in Western Africa (2014-2015). Our results show that the methods are able to obtain estimates of key epidemiological parameters that are broadly consistent with the literature, while revealing a significantly shorter distance of transmission. More importantly, in contrast to existing approaches, we are able to perform a more general model prediction that takes into account the susceptible population. Finally, our results show that, given reasonable scenarios, the framework can be an effective surrogate for susceptible-explicit individual models which are often computationally challenging

Влияние фосфатных связующих на физико-механические свойства периклазохромитовых огнеупоров

У данній статті наведено та порівняно фізико-механічні властивості периклазо-хромітових матеріалів в залежності від різних типів фосфатних зв’язуючих та введення різних домішок. Визначено, що найбільш раціональним є введення триполіфосфату натрію.In given clause are resulted and the physycal-mechanical properties periclase-cgromite of materials are compared depending on different of types phosphate binding and introduction of the various additives. Is determined, that most rational is the introduction treepolyphosphate sodume

Working here there and everywhere, challenges for researchers and employees involved in remote and mobile working

Remote and mobile workers are individuals who spend most of their working time away from a home or office base. The aim of this study was to evaluate health and wellbeing in this group using a systematic review and a questionnaire survey. The review identified that musculoskeletal symptoms, psychosocial factors and vehicle ergonomics has an impact. The questionnaire survey was affected by a low response rate but identified that both psychological distress and musculoskeletal symptom reporting were high. Relational analysis identified associations between health symptoms, psychological distress, chronic fatigue and contact with managers and colleagues. This should encourage management of this group in relation to both physical and mental health

The health and well-being of remote and mobile workers

Background: Remote and mobile workers (RMWs), people who spend the majority of work time away from a home or office base, are estimated to number 1 million in the UK and Ireland. A number of advantages and challenges have been identified with this way of working but little is known about the impact of this type of work on the health and well-being of RMWs. Aims: To identify any potential health or psychosocial effects associated with remote and mobile working, identify ergonomic factors that impact on this group and ascertain the effect of organizational or management factors that influence this occupational group. Methods: A systematic review methodology was used and a search strategy developed including keywords, which were used to search electronic databases and websites. Data were then extracted from included papers and quality assessed. Results: Initial searches identified 280 references but only 11 papers reached the inclusion criteria.Health effects identified included musculoskeletal symptoms associated with higher mileage and more time in a vehicle but a number of vehicle design issues were found to improve symptoms. Psychosocial factors including high demands were also found but better mental health was associated with higher mileage and more time with clients. There was a lack of substantive evidence in relation to managing this group. Conclusions: There is little research currently available on the general health of RMWs and future research should examine this further and focus on general health and access to support services

Changes in air quality and second-hand smoke exposure in hospitality sector businesses after introduction of the English Smoke-free legislation

Background To monitor and disseminate the short-term effects of the English Smoke-free legislation on air quality and employee exposure in businesses of the hospitality industry.Methods Indoor particle concentrations and salivary cotinine levels were measured in businesses in the hospitality sector and non-smoking employees one month before and after the implementation of the legislation. Results were immediately released to the media to announce the improvements in air quality and employee exposure to the wider public.Results Measurements were collected in 49 businesses and from 75 non-smoking individuals. Indoor PM2.5 concentrations decreased by 95% from 217μg/m3 at baseline to 11 μg/m3 at follow-up (ΡConclusion The project demonstrates the positive effects of the English Smoke-free legislation on air quality and second-hand smoke exposure in the hospitality industry sector. We believe that quick and positive feedback to the public on the effects of smoking restrictions is essential when introducing public health legislation such as the Smoke-free legislation

Tradespace analysis for multiple performance measures

To meet the changing demands of operational environments, future Department of Defense solutions require the engineering of resilient systems. Scientists, engineers and analysts rely on modeling, simulation, and tradespace analysis to design future resilient systems. During conceptual system design, high performance computing clusters and models from multiple domains are leveraged to conduct large-scale simulation experiments that generate multi-dimensional data for tradespace exploration. Despite recent breakthroughs in computation capabilities, the world’s most powerful computers cannot effectively explore a high-dimensional tradespace using a brute-force approach. This paper outlines a viable methodology and process to generate large numbers of variant solutions for tradeoff analysis. Design of experiments is used to efficiently explore a high-dimensional tradespace and identify system design drivers. These drivers are used to identify model inputs that help focus tradespace generation in areas that promise viable solutions. A dashboard illustrates how viable variant exploration can be conducted to illuminate trade decisions

IN-DEPTH REVIEW The health and well-being of remote and mobile workers

Background Remote and mobile workers (RMWs), people who spend the majority of work time away from a home or office base, are estimated to number 1 million in the UK and Ireland. A number of advantages and challenges have been identified with this way of working but little is known about the impact of this type of work on the health and well-being of RMWs. Aims To identify any potential health or psychosocial effects associated with remote and mobile working, identify ergonomic factors that impact on this group and ascertain the effect of organizational or management factors that influence this occupational group. Methods A systematic review methodology was used and a search strategy developed including keywords, which were used to search electronic databases and websites. Data were then extracted from included papers and quality assessed. Results Initial searches identified 280 references but only 11 papers reached the inclusion criteria. Health effects identified included musculoskeletal symptoms associated with higher mileage and more time in a vehicle but a number of vehicle design issues were found to improve symptoms. Psychosocial factors including high demands were also found but better mental health was associated with higher mileage and more time with clients. There was a lack of substantive evidence in relation to managing this group. Conclusions There is little research currently available on the general health of RMWs and future research should examine this further and focus on general health and access to support services