An investigation of heat transfer losses in reciprocating devices

The paper presents a detailed computational-fluid-dynamic study of the thermodynamic losses associated with heat transfer in gas springs. This forms part of an on-going investigation into high-efficiency compression and expansion devices for energy conversion applications. Axisymmetric calculations for simple gas springs with different compression ratios and using different gases are first presented, covering Peclet numbers that range from near-isothermal to near-adiabatic conditions. These show good agreement with experimental data from the literature for pressure variations, wall heat fluxes and the so-called hysteresis loss. The integrity of the results is also supported by comparison with simplified models. In order to mimic the effect of the eddying motions generated by valve flows, non-axisymmetric computations have also been carried out for a gas spring with a grid (or perforated plate) of 30% open area located within the dead space. These show significantly increased hysteresis loss at high Peclet number which may be attributed to the enhanced heat transfer associated with grid-generated motions. Finally, the implications for compressor and expander performance are discussed.This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC), Grant EP/J006246/1. It was performed using the Darwin Supercomputer of the University of Cambridge High Performance Computing Service, provided by Dell Inc. using Strategic Research Infrastructure Funding from the Higher Education Funding Council for England and funding from the Science and Technology Facilities Council

Acupuncture randomized trials (ART) in patients with chronic low back pain and osteoarthritis of the knee - Design and protocols

Background: We report on the study design and protocols of two randomized controlled trials (Acupuncture Randomized Trials = ART) that investigate the efficacy of acupuncture in the treatment of chronic low back pain and osteoarthritis of the knee, respectively. Objective: To investigate whether acupuncture is more efficacious than (a) no treatment or (b) minimal acupuncture in the treatment of low back pain and osteoarthritis. Design: Two randomized, controlled, multicenter trials with three treatment arms and a total follow-up time of 52 weeks. Setting: 30 practitioners and outpatient units in Germany specialized in acupuncture treatment. Patients: 300 patients will be included in each study. In the low back pain trial, patients will be included according to clinical diagnosis. In the osteoarthritis pain trial, patients will be included according to the American College of Rheumatology criteria. Interventions: Patients are randomly assigned to receive either (1) semi-standardized acupuncture (150 patients), (2) minimal acupuncture at non-acupuncture points (75 patients), or (3) no treatment for two months followed by semi-standardized acupuncture (75 patients, waiting list control). Acupuncture treatment consists of 12 sessions per patient over a period of 8 weeks. Main Outcome Measure: The main outcome measure is the difference between baseline and the end of the 8-week treatment period in the following parameters: pain intensity as measured by a visual analogue scale (VAS; 0-100 mm) in the low back pain trial and by the Western Ontario and McMaster Universities Osteoarthritis Score (WOMAC) in the osteoarthritis trial. Outlook: The results of these two studies (available in 2004) will provide health care providers and policy makers with the information needed to make scientifically sound assessments of acupuncture therapy

PCV39 THE EFFECT OF GENDER ON HEALTH-RELATED QUALITY OF LIFE AFTER CORONARY STENT IMPLANTATION

En esta emisión hablaremos sobre la importancia e estudiar humanidades en en la UMN

Acupuncture in Seasonal Allergic Rhinitis (ACUSAR) - Design and Protocol of a Randomised Controlled Multi-Centre Trial

Background: We report on the study design and protocol of a randomised controlled trial (Acupuncture in Seasonal Allergic Rhinitis, ACUSAR) that investigates the efficacy of acupuncture in the treatment of seasonal allergic rhinitis (SAR). Objective: To investigate whether acupuncture is non-inferior or superior to (a) penetrating sham acupuncture and (b) rescue medication in the treatment of SAR. Design: 3-armed, randomised controlled multi-centre trial with a total follow-up time of 16 weeks in the 1st year and 8 weeks in the 2nd year. Setting: 41 physicians in 37 out-patient units in Germany specialised in acupuncture treatment. Patients: 400 seasonal allergic rhinitis patients with clinical symptoms and test-positive (skin-prick test and/or specific IgE) to both birch and grass pollen. Interventions: Patients will be randomised in a 2:1:1 ratio to one of three groups: (a) semi-standardised acupuncture plus rescue medication (cetirizine); (b) penetrating sham acupuncture at non-acupuncture points plus rescue medication; or (c) rescue medication alone for 8 weeks (standard treatment group). Acupuncture and sham acupuncture will consist of 12 treatments per patient over 8 weeks. Main Outcome Measures: Average means of the Rhinitis Quality of Life Questionnaire (RQLQ) overall score and the Rescue Medication Score (RMS) between weeks 6 and 8 in the first year, adjusted for baseline values. Outlook: The results of this trial available in 2011 will have a major impact on the decision of whether acupuncture should be considered as a therapeutic option in the treatment of SAR

Application of In-Situ Diagnostic Methods for the Study of SOFC Operational Behaviour

In order to optimise the operational behaviour of fuel cells and minimise cell degradation it is very helpful to use in-situ and ex-situ analytical methods. The application of advanced diagnostic methods by monitoring cell characteristics under real operating conditions provides valuable information to be used for the development of degradation mitigation strategies. The application of these methods in SOFC development is significantly limited mainly due to the experimental problems that are associated with the high operating temperature. However, an increasing effort in developing and implementing non-traditional analytical methods such as spatially resolved measurements and imaging techniques for SOFC development has been made in recent years. The presentation gives an overview of in-situ diagnostic methods that are applied at DLR Stuttgart for the study of SOFCs. It includes spatially resolved measurements with an experimental segmented cell configuration where different techniques such as IV characteristics, impedance spectroscopy, gas chromatography and temperature measurement are involved. The investigation by means of segmented cells aims at the determination of local effects and the identification of critical operating conditions during technically relevant SOFC operation. Recently, a new test setup with transparent optical access has been built up allowing for microscopic observation of processes within the cell as well as for application of in-situ laser Raman spectroscopy to determine highly resolved concentrations of gas species along a flow channel. Examples of analytical studies by applying these diagnostic methods are presented and potentials and limitations of the different techniques are discussed

Determinants of Physical Activity and Screen Time Trajectories in 7th to 9th Grade Adolescents-A Longitudinal Study

Physical activity (PA) in youth tends to decline with increasing age, while sedentary behaviour including screen time (ST) increases. There are adolescents, however, whose PA and ST do not follow this pattern. The aim of this study is (i) to examine trajectories in PA and ST from grade 7-9 among students in Berlin, and (ii) to investigate the relationship of these trajectories with individual factors and school type. For the present analyses, changes in students' PA and ST across three time points from 7th to 9th grade were assessed via self-report questionnaires. Positive and negative trajectories were defined for both PA (positive: increasing or consistently high, negative: decreasing or consistently low) and ST (vice versa). Multivariable logistic regression analyses were performed to identify possible predictors of PA and ST trajectories. In total, 2122 students were included (50.2% girls, mean age 12.5 (standard deviation 0.7) years). Compared to grade 7, less students of grade 9 fulfilled PA and ST recommendations (PA: 9.4% vs. 13.2%; ST: 19.4% vs. 25.0%). The positive PA trajectory included 44% of all students (63% boys), while the positive ST trajectory included 21% of all students (30% boys). Being a boy was significantly associated with a positive PA trajectory, while being a girl, having a high socioeconomic status, and attending a high school, were significantly associated with a positive ST trajectory. Different PA and ST trajectories among adolescents should be taken into account when implementing prevention programs for this target group

study design and methodology

Background The hazardous health effects of smoking are established, but there remains a need to evaluate existing smoking prevention strategies and to increase their effectiveness in adolescents. Strategies focusing on parental attitudes and rule setting have been identified as a potentially effective approach. The present manuscript describes objectives, study design and methodology of the BEST Prevention study. Methods/design BEST Prevention is a three-armed cluster randomized-controlled trial among 7th grade (11–16 years) students in Berlin, Germany. Schools were enrolled between 2010 and 2011 and allocated using a centralized randomization list into 1) a student smoking prevention intervention (visit to an established interactive circuit), 2) the same intervention plus a parent intervention, and 3) a control group (visit to an established exercise and nutrition interactive circuit). Students were assessed at baseline, 12 and 24 months via self-report, as well as via carbon monoxide and cotinine in saliva at the 24 month follow-up. Statistical analyses uses multi-level regression models with cluster effects (school and class within school) based on the intention to treat population. Here we report descriptive baseline characteristics of recruited schools, and schools classes. Two schools from the control group dropped out after allocation. Hence, 47 secondary schools from all 12 districts of the city, including 161 school classes and 3023 students are participating in the study. Of those, 2801 students completed the baseline assessment. Discussion The present manuscript provides details on the study design and methodology of a large school-based smoking prevention trial in a metropolitan area in Germany. Findings from this study will yield important insight into the long-term effectiveness of specific smoking prevention strategies, also in disadvantaged population groups

Efficacy and cost-effectiveness of the 13C-urea breath test as the primary diagnostic investigation for the detection of Helicobacter pylori infection compared to invasive and non-invasive diagnostic tests

Background: Helicobacter pylori (H. pylori) is one of the most common bacterial infections in humans. There is a risk factor for gastric or duodenal ulcers, gastric cancer and MALT (Mucosa Associated Lymphoid Tissue)-Lymphomas. There are several invasive and non-invasive methods available for the diagnosis of H. pylori. The 13C-urea breath test is a non-invasive method recommended for monitoring H. pylori eradication therapy. However, this test is not yet used for primary assessment of H. pylori in Germany. Objectives: What are the clinical and health economic benefits of the 13C-urea breath test in the primary assessment of H. pylori compared to other invasive and non-invasive methods? Methods: A systematic literature search including a hand search was performed for studies investigating test criteria and cost-effectiveness of the 13C-urea breath test in comparison to other methods used in the primary assessment of H. pylori. Only studies that directly compared the 13C-urea breath test to other H. pylori-tests were included. For the medical part, biopsy-based tests were used as the gold standard. Results: 30 medical studies are included. Compared to the immunoglobulin G (IgG) test, the sensitivity of the 13C-urea breath test is higher in twelve studies, lower in six studies and one study reports no differences. The specificity is higher in 13 studies, lower in three studies and two studies report no differences. Compared to the stool antigen test, the sensitivity of the 13C-urea breath test is higher in nine studies, lower in three studies and one study reports no difference. The specificity is higher in nine studies, lower in two studies and two studies report no differences. Compared to the urease test, the sensitivity of the 13C-urea breath test is higher in four studies, lower in three studies and four studies report no differences. The specificity is higher in five studies, lower in five studies and one study reports no difference. Compared to histology, the sensitivity of the 13C-urea breath test is higher in one study and lower in two studies. The specificity is higher in two studies and lower in one study. One study each compares the 13C-urea breath test to the 14C-urea breath test and the polymerase chain reaction (PCR) test, respectively, and reports no difference in sensitivity and specificity with the 14C-urea breath test, and lower sensitivity and higher specificity compared to PCR. The statistical significance of these differences is described for six of the 30 studies. Nine health economic evaluations are included in the Health Technology Assessment (HTA) report. Among these studies, the test-and-treat strategy using the 13C-urea breath test is compared to test-and-treat using serology in six analyses and to test and treat using the stool antigen test in three analyses. Thereby, test-and-treat using the breath test is shown to be cost-effective over the serology based strategy in three models and is dominated by a test-and-treat strategy using the stool antigen test in one model. A cost-effectiveness comparison between the urea breath test approach and the empirical antisecretory therapy is carried out in four studies. Of these, two studies report that the strategy using the urea breath test is cost-effective over the empirical antisecretory therapy. In two studies, test-and-treat using the 13C-urea breath test is compared to the empirical eradication therapy and in five studies to endoscopy-based strategies. The breath test approach dominates endoscopy in two studies and is dominated by this strategy in one study. Discussion: All included medical and economic studies are limited to a greater or lesser extent. Additionally, the results of the studies are heterogeneous regarding medical and economic outcomes respectively. Thus, the majority of the medical studies do not report the statistical significance of the differences in sensitivity and specificity. In direct comparisons the 13C- urea breath test shows higher sensitivity and specificity than the IgG and stool antigen tests. In comparison to the urease test, results for sensitivity are inconsistent, and the specificity is slightly higher for the 13C-urea breath test. There are not enough results for comparisons between the 13C-urea breath test and the 14C-urea breath test, histology and PCR to describe tendencies. The included economic studies suggest that the test-and-treat strategy using the 13C-urea breath test is cost-effective compared to test-and-treat using serology as well as empirical antisecretory therapies. Due to a lack of valid studies, it is not possible to assess the breath test approach in comparison to test-and-treat using the stool antigen test and the empirical eradication therapy respectively, regarding the cost-effectiveness. The results of economic analyses comparing test-and-treat using the breath test to endoscopy strategies are too heterogeneous to draw any conclusions. Overall, none of the included economic models is able to completely capture the complexity of managing patients with dyspeptic complaints. Conclusions/Recommendations: Based on available medical and economic studies, there is no sufficient evidence to recommend test and-treat using 13C-urea breath testing for the detection of H. pylori infection as the standard procedure for the management of uninvestigated dyspepsia in the German health care system. In addition, it must be considered that the DVGS guidelines of the Deutsche Gesellschaft für Verdauungs- und Stoffwechselkrankheiten (DVGS) recommend endoscopy based methods for the management of patients with dyspeptic complaints

Разработка технологического процесса изготовления ротора ФЮРА.612322. 401.0.33.91.110

Выпускная квалификационная работа выполнена на тему «Разработка технологического процесса изготовления ротора» ФЮРА.612322.401.0.33.91.110 геохода в условиях мелкосерийного производства. Выпускная квалификационная работа состоит из 8 листов графического материала, 77 листов пояснительной записки. Целью работы является разработка технологического процесса, с использованием высокоэффективного оборудования, приспособлений, что позволяет сократить время на подготовку производства, снизить трудоемкость и затраты на производство. Ключевые слова: ТЕХНОЛОГИЧЕСКИЙ ПРОЦЕСС, ЗАГОТОВКА, ДЕТАЛЬ, РОТОР, ИНСТРУМЕНТ, СТАНОК, ПРИСПОСОБЛЕНИЕ, СВЕРЛЕНИЕ. Выпускная квалификационная работа состоит из следующих основных частей: Аналитическая часть, где приводится описание: служебного назначения изделия, действуFinal qualifying work done on the topic "Development of technological process of manufacturing the rotor" FYURA.612322.401.0.33.91.110 geohoda in small-scale production. Final qualifying work consists of 8 sheets of graphics, 77 pages of the explanatory note. The aim is to develop a process, using high-performance equipment, devices, reducing the time to prepare production, reduce the complexity and costs of production. Keywords: workflow, PROCESSING, PART ROTOR, TOOLS, MACHINES, TOOLS, DRILLING. Final qualifying work consists of the following parts: The analytical part, which describes: official purpose products, the current process, the completion of construction details on manufacturability. The technological part of the project includes the following issues: selection of preparations

Improving Vehicle Detour in Dynamic Ridesharing using Transfer Stops

Ridesharing companies like Uber or Lyft provide an alternative to classic public transport, in which you can order a ride from anywhere to anywhere within the service area via an app. A vehicle will be assigned to you, pick you up and drive you to your destination. In services like UberXShare or LyftShared, other passengers might also be picked up on the way, causing a small detour. The process of matching your ridesharing request to some vehicle in the set of available vehicles is resolved using a dispatching algorithm. Buchhold et al. in [3] developed the dispatching algorithm LOUD for the dynamic ridesharing scenario. It is able to find the optimal solution to a ridesharing request (based on a given cost function) in only a few milliseconds on realistically sized scenarios. In this thesis, we aim to add transfer stops to ridesharing by extending the LOUD-algorithm. We present multiple transfer-dispatching algorithms and implement and evaluate each of these algorithms thoroughly, analyzing their runtime performance and dispatching quality on various different scenarios. Our best algorithm, where transfer vertices are sampled by betweenness, is able to find a better solution to a ridesharing request than LOUD in up to 20% of all requests, while only increasing the required runtime by about one order of magnitude. Furthermore, we are able to show that multi-transfer routes can bring substantial improvements over no- or one-transfer-routes on long-distance requests, and we show that runtime performance scales well with the number of requested transfer stops