Finite element analysis of conformal contacts in water hydraulic axial piston pumps incorporating advanced ceramic materials

The use of water as a hydraulic fluid in a pump necessitates the use of conformal contacts to reduce the high rates of wear and leakage losses that result from the low viscosity and lubricity of water. Swashplate type axial piston pumps are ideal in this respect because they incorporate such conformal contacts. Furthermore, the development of such a pump for use with water, especially sea-water, critically relies on the correct selection and application of materials.The purpose of this research work is firstly to examine the contact conditions within an axial piston pump for a range of sleeved and lined components manufactured from a variety of different materials. The use of finite element analysis with gap elements is a useful way of determining the contact pressure distribution between conformally contacting components. It is shown that this method gives excellent agreement with available analytical methods for the two-dimensional cylindrical and axisymmetric spherical cases, and thus can be extended to layered components. Extension to three dimensions, when the contact cannot be accounted for by plane strain or plane stress conditions, is also possible, allowing a much more representative analysis of the contact conditions within an axial piston pump. No single combination of materials is identified as being the most suitable, rather, the method enables the consequences of choosing materials for their tribological characteristics to be examined.Once the contact conditions are known within the pump it is then possible to more accurately design the pump components. However, conventional deterministic methods are not appropriate for designing ceramic components, due to the inherent scatter of limiting defects, and statistical methods are necessary. Thus the second part of this research work is aimed at reviewing and examining the different probabilistic design methods with the long-term view of determining which, if any, are best suited to the design of ceramic components in this particular application. It is conduded that no single method adequately predicts the probability of failure of ceramic specimens with more complex stress distributions than four-point flexure bars

Structural response of a compliant pipe-in-pipe under frictionless and frictional conditions of the seabed.

Pipe-in-Pipe (PIP) technology has been studied significantly owing to its superior performance in deep-water and high-pressure high temperature fields than conventional single pipe. The PIP system has excellent track record of mitigating flow assurance problems from subsea wells through maintenance of the fluid's temperature in the pipe. It has also been applied in marine environment where conventional single pipe cannot perform. However, owing to complex interaction and contact within the PIP system and seabed, the mechanism of load transfer and the stresses that developed due to pressure, temperature and combined loading has not been fully understood and quantified. Therefore, this study examined the effect of pressure, temperature and the combined loading on PIP systems for flat seabed subsea pipeline. Simulations are performed to examined frictional and frictionless conditions of the flat seabed on PIP system and individual results of inner pipe, insulation material and outer pipe are presented for each analysis. The analytical calculations are carried-out for determining the operating stresses in each component of the PIP system in view of its significance for the overall structural behaviour of the system and validation of the numerical model. The impact response of the inner pipe, insulation and the outer pipe based on pressure, temperature and the combination of both (pressure and temperature) and the resulting stress on each component of the PIP system are investigated and the result presented. Furthermore, results of axial, radial and hoop stresses for the individual loading condition and with coupled analysis corresponding to each simulation (Frictional and Frictionless seabed conditions) are found to be closely similar with percentage difference less than 5 except for the von Mises stress which give 5.3%. This interesting finding revealed that the friction force does not affect structural integrity of the PIP system compared to conventional - single pipeline assuming all other parameters remains constant. Moreover, the presence of the outer pipe and the insulation material enhanced the performance of the inner pipe. The numerical simulation predicts closely the impact response for pipe-in-pipe composite specimens under individual and combined loading conditions. Therefore, the results obtained will serve as a reference guide for designing, construction and operating PIP system in the future to develop unconventional challenging energy resources like High Pressure High Temperature fields

Web-based physiotherapy for people affected by multiple sclerosis: a single blind, randomized controlled feasibility study

Objective: To examine the feasibility of a trial to evaluate web-based physiotherapy compared to a standard home exercise programme in people with multiple sclerosis. Design: Multi-centre, randomized controlled, feasibility study. Setting: Three multiple sclerosis out-patient centres. Participants: A total of 90 people with multiple sclerosis (Expanded Disability Status Scale 4–6.5). Interventions: Participants were randomized to a six-month individualized, home exercise programme delivered via web-based physiotherapy (n = 45; intervention) or a sheet of exercises (n = 45; active comparator). Outcome measures: Outcome measures (0, three, six and nine months) included adherence, two-minute walk test, 25 foot walk, Berg Balance Scale, physical activity and healthcare resource use. Interviews were undertaken with 24 participants and 3 physiotherapists. Results: Almost 25% of people approached agreed to take part. No intervention-related adverse events were recorded. Adherence was 40%–63% and 53%–71% in the intervention and comparator groups. There was no difference in the two-minute walk test between groups at baseline (Intervention-80.4(33.91)m, Comparator-70.6(31.20)m) and no change over time (at six-month Intervention-81.6(32.75)m, Comparator-74.8(36.16)m. There were no significant changes over time in other outcome measures except the EuroQol-5 Dimension at six months which decreased in the active comparator group. For a difference of 8(17.4)m in two-minute walk test between groups, 76 participants/group would be required (80% power, P > 0.05) for a future randomized controlled trial. Conclusion: No changes were found in the majority of outcome measures over time. This study was acceptable and feasible by participants and physiotherapists. An adequately powered study needs 160 participants

The Maunakea Spectroscopic Explorer Book 2018

(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is intended as a concise reference guide to all aspects of the scientific and technical design of MSE, for the international astronomy and engineering communities, and related agencies. The current version is a status report of MSE's science goals and their practical implementation, following the System Conceptual Design Review, held in January 2018. MSE is a planned 10-m class, wide-field, optical and near-infrared facility, designed to enable transformative science, while filling a critical missing gap in the emerging international network of large-scale astronomical facilities. MSE is completely dedicated to multi-object spectroscopy of samples of between thousands and millions of astrophysical objects. It will lead the world in this arena, due to its unique design capabilities: it will boast a large (11.25 m) aperture and wide (1.52 sq. degree) field of view; it will have the capabilities to observe at a wide range of spectral resolutions, from R2500 to R40,000, with massive multiplexing (4332 spectra per exposure, with all spectral resolutions available at all times), and an on-target observing efficiency of more than 80%. MSE will unveil the composition and dynamics of the faint Universe and is designed to excel at precision studies of faint astrophysical phenomena. It will also provide critical follow-up for multi-wavelength imaging surveys, such as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation Very Large Array.Comment: 5 chapters, 160 pages, 107 figure

Astrophysical Tests of Dark Matter with Maunakea Spectroscopic Explorer

We discuss how astrophysical observations with the Maunakea Spectroscopic Explorer (MSE), a high-multiplexity (about 4300 fibers), wide field-of-view (1.5 square degree), large telescope aperture (11.25 m) facility, can probe the particle nature of dark matter. MSE will conduct a suite of surveys that will provide critical input for determinations of the mass function, phase-space distribution, and internal density profiles of dark matter halos across all mass scales. N-body and hydrodynamical simulations of cold, warm, fuzzy and self-interacting dark matter suggest that non-trivial dynamics in the dark sector could have left an imprint on structure formation. Analysed within these frameworks, the extensive and unprecedented datasets produced by MSE will be used to search for deviations away from cold and collisionless dark matter model. MSE will provide an improved estimate of the local density of dark matter, critical for direct detection experiments, and will improve estimates of the J-factor for indirect searches through self-annihilation or decay into Standard Model particles. MSE will determine the impact of low mass substructures on the dynamics of Milky Way stellar streams in velocity space, and will allow for estimates of the density profiles of the dark matter halos of Milky Way dwarf galaxies using more than an order of magnitude more tracers. In the low redshift Universe, MSE will provide critical redshifts to pin down the luminosity functions of vast numbers of satellite systems, and MSE will be an essential component of future strong lensing measurements to constrain the halo mass function. Across nearly all mass scales, the improvements offered by MSE, in comparison to other facilities, are such that the relevant analyses are limited by systematics rather than statistics.Comment: 44 pages, 19 figures. To appear as a chapter for "The Detailed Science Case for the Maunakea Spectroscopic Explorer, 2019

Multimorbidity and the risk of major adverse kidney events: findings from the UK Biobank cohort

Background: Multimorbidity (the presence of two or more long-term conditions) is associated with a heightened risk of mortality, but little is known about its relationship with the risk of kidney events. Methods: Associations between multimorbidity and major adverse kidney events (MAKE: the need for long-term kidney replacement therapy, doubling of serum creatinine, fall of estimated glomerular filtration rate (eGFR) to < 15 ml/min/1.73m2 or 30% decline in eGFR) were studied in 68,505 participants from the UK Biobank cohort. Participants were enrolled in the study between 2006 and 2010. Associations between long-term condition counts and MAKE were tested using survival analyses accounting for the competing risk of death. Results: Over a median follow-up period of 12.0 years, 2,963 participants had MAKE. There were associations between long-term condition count categories and the risk of MAKE (one long-term condition adjusted subhazard ratio (sHR) 1.29 (95% Confidence Interval 1.15-1.45), 2 long-term conditions sHR 1.74 (1.55-1.96), three or more long-term conditions sHR 2.41 (2.14-2.71)). This finding was more pronounced when only cardiometabolic long-term conditions were considered (one long-term condition sHR 1.58 (1.45-1.73), two long-term conditions sHR 3.17 (2.80-3.59), three or more long-term conditions sHR 5.24 (4.34-6.33)). Combinations of long-term conditions associated with MAKE were identified. Diabetes, hypertension and coronary heart disease featured most commonly in high-risk combinations. Conclusions: Multimorbidity, and in particular cardiometabolic multimorbidity, is a risk factor for MAKE. Future research should study groups of patients who are at high risk of progressive kidney disease based on the number and type of long-term conditions

Study protocol of European Fans in Training (EuroFIT):a four-country randomised controlled trial of a lifestyle program for men delivered in elite football clubs

Background: Lifestyle interventions targeting physical activity, sedentary time and dietary behaviours have the potential to initiate and support behavioural change and result in public health gain. Although men have often been reluctant to engage in such lifestyle programs, many are at high risk of several chronic conditions. We have developed an evidence and theory-based, gender sensitised, health and lifestyle program (European Fans in Training (EuroFIT)), which is designed to attract men through the loyalty they feel to the football club they support. This paper describes the study protocol to evaluate the effectiveness and cost-effectiveness of the EuroFIT program in supporting men to improve their level of physical activity and reduce sedentary behaviour over 12 months. Methods: The EuroFIT study is a pragmatic, two-arm, randomised controlled trial conducted in 15 football clubs in the Netherlands, Norway, Portugal and the UK (England). One-thousand men, aged 30 to 65 years, with a self-reported Body Mass Index (BMI) ≥27 kg/m2 will be recruited and individually randomised. The primary outcomes are objectively-assessed changes in total physical activity (steps per day) and total sedentary time (minutes per day) at 12 months after baseline assessment. Secondary outcomes are weight, BMI, waist circumference, resting systolic and diastolic blood pressure, cardio-metabolic blood biomarkers, food intake, self-reported physical activity and sedentary time, wellbeing, self-esteem, vitality and quality of life. Cost-effectiveness will be assessed and a process evaluation conducted. The EuroFIT program will be delivered over 12 weekly, 90-minute sessions that combine classroom discussion with graded physical activity in the setting of the football club. Classroom sessions provide participants with a toolbox of behaviour change techniques to initiate and sustain long-term lifestyle changes. The coaches will receive two days of training to enable them to create a positive social environment that supports men in engaging in sustained behaviour change. Discussion: The EuroFIT trial will provide evidence on the effectiveness and cost-effectiveness of the EuroFIT program delivered by football clubs to their male fans, and will offer insight into factors associated with success in making sustained changes to physical activity, sedentary behaviour, and secondary outcomes, such as diet.Trial registration: ISRCTN: 81935608. Registered 16 June 2015.<br/

Dropout from exercise trials among cancer survivors—An individual patient data meta-analysis from the POLARIS study

Introduction: The number of randomized controlled trials (RCTs) investigating the effects of exercise among cancer survivors has increased in recent years; however, participants dropping out of the trials are rarely described. The objective of the present study was to assess which combinations of participant and exercise program characteristics were associated with dropout from the exercise arms of RCTs among cancer survivors. Methods: This study used data collected in the Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS) study, an international database of RCTs investigating the effects of exercise among cancer survivors. Thirty-four exercise trials, with a total of 2467 patients without metastatic disease randomized to an exercise arm were included. Harmonized studies included a pre and a posttest, and participants were classified as dropouts when missing all assessments at the post-intervention test. Subgroups were identified with a conditional inference tree. Results: Overall, 9.6% of the participants dropped out. Five subgroups were identified in the conditional inference tree based on four significant associations with dropout. Most dropout was observed for participants with BMI &gt;28.4 kg/m2, performing supervised resistance or unsupervised mixed exercise (19.8% dropout) or had low-medium education and performed aerobic or supervised mixed exercise (13.5%). The lowest dropout was found for participants with BMI &gt;28.4 kg/m2 and high education performing aerobic or supervised mixed exercise (5.1%), and participants with BMI ≤28.4 kg/m2 exercising during (5.2%) or post (9.5%) treatment. Conclusions: There are several systematic differences between cancer survivors completing and dropping out from exercise trials, possibly affecting the external validity of exercise effects.</p

Moderators of Exercise Effects on Cancer-related Fatigue:A Meta-analysis of Individual Patient Data

PURPOSE: Fatigue is a common and potentially disabling symptom in patients with cancer. It can often be effectively reduced by exercise. Yet, effects of exercise interventions might differ across subgroups. We conducted a meta-analysis using individual patient data of randomized controlled trials (RCT) to investigate moderators of exercise intervention effects on cancer-related fatigue. METHODS: We used individual patient data from 31 exercise RCT worldwide, representing 4366 patients, of whom 3846 had complete fatigue data. We performed a one-step individual patient data meta-analysis, using linear mixed-effect models to analyze the effects of exercise interventions on fatigue (z score) and to identify demographic, clinical, intervention- and exercise-related moderators. Models were adjusted for baseline fatigue and included a random intercept on study level to account for clustering of patients within studies. We identified potential moderators by testing their interaction with group allocation, using a likelihood ratio test. RESULTS: Exercise interventions had statistically significant beneficial effects on fatigue (β = -0.17; 95% confidence interval [CI], -0.22 to -0.12). There was no evidence of moderation by demographic or clinical characteristics. Supervised exercise interventions had significantly larger effects on fatigue than unsupervised exercise interventions (βdifference = -0.18; 95% CI -0.28 to -0.08). Supervised interventions with a duration ≤12 wk showed larger effects on fatigue (β = -0.29; 95% CI, -0.39 to -0.20) than supervised interventions with a longer duration. CONCLUSIONS: In this individual patient data meta-analysis, we found statistically significant beneficial effects of exercise interventions on fatigue, irrespective of demographic and clinical characteristics. These findings support a role for exercise, preferably supervised exercise interventions, in clinical practice. Reasons for differential effects in duration require further exploration