Dynamic Behaviour of EHD-contacts using a regularised, mass conserving Cavitation Algorithm

The paper deals with the holistic simulation of systems supported in journal bearings, which is demonstrated using the example of a conrod’s big end bearing. For that purpose, primarily the interactions of multibody-, structureand hydrodynamics have to be described. Based on the time integration of the global equations of motions, the non-linear bearing forces in the fluid film and the elastic deformation of the bearings surfaces have to be modelled adequately concerning their mutual influence. The implementation of the elastic structure is carried out by means of a hierarchised, IRS–based1modal reduction in order to represent its eigenbehaviour as realistic as possible and to fulfil the requirement of low computational costs by reducing the number of degree of freedoms. Additionally, the journal bearing is considered by an online solution of the Reynolds equation, whereat the cavitation is handled by a transient acting, mass-conserving algorithm. This is based on the classical Elrod algorithm, but was extended by a regularisation, which enables a faster and more stable solution. Due to the general approach, both mechanical and tribological output quantities are accessible. This provides the possibility to draw a comparison with simpler approaches and to emphasize the benefit of the described procedure

Effects of yoga and mindfulness practices on the autonomous nervous system in primary school children: A non-randomised controlled study

Objectives: The present study examined the effects of a yoga and mindfulness-based programme on the autonomic nervous system of primary school children by using heart rate variability parameters. Design: A two-arm non-randomised controlled trial compared an integrated yoga and mindfulness-based programme (16 weeks) to conventional primary school lessons. Setting: Primary school classrooms and conference rooms. Interventions: Participants were allocated to a 16-week integrated yoga-based programme or conventional school lessons. A subgroup was randomised to receive 24h electrocardiogram-recordings. Main outcome measures: Heart rate variability indices were measured, both linear (time and frequency domain) and non-linear (symbolic dynamics, compression entropy), calculated from 30-minute extracts of Holterelectrocardiogram-recordings. Assessments were conducted at baseline and at the end of intervention. Results: 40 participants (42.5% female) were included into the analysis of HRV. No significant changes in heart rate variability parameters were observed between the groups after 16 weeks. In the intervention group, a trend towards increased parasympathetic activity could be seen over time, although not significantly enhanced compared to the control group. Conclusion: Results obtained here do not clearly show that children in German primary school settings benefit from an integrated yoga-based intervention. However, exploratory post-hoc analyses point interestingly to an increased nocturnal parasympathetic activity in the intervention group. Further studies are required with highquality study designs, larger sample sizes and longer-term follow-ups

Racial Disparities in Emergency General Surgery: Do Differences in Outcomes Persist Among Universally Insured Military Patients?

Research Objective: Described as one of the most serious health problems affecting the nation, racial disparities are estimated to account for \u3e83,000 deaths, \u3e$57 billion per year. They have been identified in multiple surgical settings, including differences in outcomes by race among emergency general surgery(EGS) patients. As many minority patients are uninsured, increasing access to care is thought to be a viable solution to mitigate inequities. The objectives of this study were to determine whether racial disparities in 30/90/180day outcomes exist within a universally-insured population of military/civilian-dependent EGS patients and whether differences in outcomes differentially persist in care received at military-vs-civilian hospitals and among sponsors who are enlisted-service members-vs-officers. It also considered longer-term outcomes of care. Study Design: Risk-adjusted survival analyses using Cox proportional-hazards models assessed race-based differences in mortality, major morbidity, and readmission from index-hospital admission (discharge for readmission) through 30/90/180days. Models accounted for hospital clustering and possible biases associated with missing race (reweighted-estimating equations). Sub-analyses considered effects restricted to operative interventions, stratified by 24 EGS-diagnostic categories defined by the American Association for the Surgery of Trauma(AAST), and effect modification related to rank (SES-proxy: officers-vs-enlisted-sponsors) and military-vs-civilian-hospital care. Population Studied: Five years of national TRICARE Prime/Prime-plus data, which provides insurance to active/reserve/retired members of the US Armed Services and dependents, were queried for adults (≥18y) with primary EGS conditions, defined by the AAST. Patients who did not have an index admission between 01/01/2006-01/07/2010 (minimum 180days follow-up) or who were not continuously enrolled in TRICARE for 180days were excluded. Non-surviving patients were retained while they survived. Principal Findings: A total of 101,011 patients were included: 73.5% White, 14.5% Black, 4.4% Asian, 7.7% other. Risk-adjusted analyses reported equivalent-or-better mortality and readmission outcomes among minority patients at 30/90/180days—even when restricted to civilian hospitals where studies suggest that EGS disparities are found. Readmissions within military hospitals were lower among minority patients. Major morbidity was higher among Black versus White patients (HR[95%CI]): 30day-1.23[1.13-1.35], 90day-1.18[1.09-1.28], 180day-1.15[1.07-1.24]—a finding driven by appendiceal disorders (HR:1.69-1.70). No other diagnostic category-based HR was significant. When considered by rank, significant effects were isolated to enlisted-service members. However, given the relatively small number of patients who were (dependents of) officers, it is difficult to determine whether rank-based findings are a result of social determinants or influenced by the limited number of minority patients. Conclusions: The first of its kind to examine racial disparities in longer-term outcomes of EGS care, this longitudinal analysis of military patients demonstrated apparent mitigation of racial disparities within a universally-insured health system when compared to the overall US health system. Efforts to explain findings based on consideration of care provided in military-vs-civilian hospitals, among specific EGS-diagnostic categories, and based on sponsor rank revealed modification of the association between race and outcomes to some extent for all three. Implications for Policy or Practice: The contrast between results for universally-insured military/civilian-dependent patients and reported disparities among all US civilian patients merits consideration. The data speak to the importance of insurance-coverage in the development of disparities interventions nationwide and will help to inform policy within the DoD

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

SIMULATION VON SCHWIMMBUCHSENLAGERUNGEN IN ABGASTURBOLADERN

Der Beitrag behandelt die Berechnung eines vollständigen Hochlaufs der Turboladerwelle auf Betriebsdrehzahl zur Untersuchung der Stabilität der Lagerung. Aus der Schwimmbuchsenlagerung resultieren zum einen spezielle Randbedingungen, die zur Kopplung von innerem und äußerem Schmierfilm führen. Zum anderen ist dadurch der Rotor in der Lage sich derart schiefzustellen, dass die Berechnung der hydrodynamischen Schmierfilmdrücke unter Annahme eines Parallelspalts nicht mehr gerechtfertigt ist. Die Modellierung erfolgt daher innerhalb eines Mehrkörpersystems(MKS), wobei die Reynolds Differentialgleichung in jedem Zeitschritt unter Verwendung der Finiten-Elemente-Methode gelöst wird. Abschließend erfolgt ein Vergleich zwischen gemessenen Daten und numerischer Simulation. Dabei wird der Einfluss der Berücksichtigung der Wellenschiefstellung sowie der Kommunikationsbohrungen bei der Lösung der Reynolds DGL auf die Ausbildung des instabilen Bereichs diskutiert.This paper deals with the calculation of a full-dynamical run-up of a turbocharger shaft up to operating speed to investigate the stability of the bearing. Due to the full floating ring bearings special boundary conditions result, which lead to a coupling of outer and inner lubrication film. Furthermore the rotor is able to take a skew position in such a way, that for the solution of Reynolds equation the simplistic assumption of a parallel gap isn’t longer valid. Therefore the modeling is done in a multi-body-system(MBS), whereat the finite element method is used for the calculation of hydrodynamic pressures in every timestep. Concluding a comparison is done between measured data and numerical simulation. Thereby the development of the instable region is discussed by the influence of shaft inclination as well as thecommunication drill-holes

Simulation von schwimmbuchsenlagerungen in Abgasturboladern

Der Beitrag behandelt die Berechnung eines vollständigen Hochlaufs der Turboladerwelle auf Betriebsdrehzahl zur Untersuchung der Stabilität der Lagerung. Aus der Schwimmbuchsenlagerung resultieren zum einen spezielle Randbedingungen, die zur Kopplung von innerem und äußerem Schmierfilm führen. Zum anderen ist dadurch der Rotor in der Lage sich derart schiefzustellen, dass die Berechnung der hydrodynamischen Schmierfilmdrücke unter Annahme eines Parallelspalts nicht mehr gerechtfertigt ist. Die Modellierung erfolgt daher innerhalb eines Mehrkörpersystems (MKS), wobei die Reynolds Differentialgleichung in jedem Zeitschritt unter Verwendung der Finiten-Elemente-Methode gelöst wird. Abschließend erfolgt ein Vergleich zwischen gemessenen Daten und numerischer Simulation. Dabei wird der Einfluss der Berücksichtigung der Wellenschiefstellung sowie der Kommunikationsbohrungen bei der Lösung der Reynolds DGL auf die Ausbildung des instabilen Bereichs diskutiert.This paper deals with the calculation of a full-dynamical run-up of a turbocharger shaft up to operating speed to investigate the stability of the bearing. Due to the full floating ring bearings special boundary conditions result, which lead to a coupling of outer and inner lubrication film. Furthermore the rotor is able to take a skew position in such a way, that for the solution of Reynolds equation the simplistic assumption of a parallel gap isn’t longer valid. Therefore the modeling is done in a multi-body-system (MBS), whereat the finite element method is used for the calculation of hydrodynamic pressures in every timestep. Concluding a comparison is done between measured data and numerical simulation. Thereby the development of the instable region is discussed by the influence of shaft inclination as well as the communication drill-holes