Influence of GPS measurements quality to NTP time-keeping

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The technique of quick designing of casting panel for plastic gear wheel injection

Sadašnji tehnološki nivo strojarstva zahtijeva aktivnu primjenu softvera u svim stadijima izrade nekog strojarskog projekta – proizvoda. Izraz proizvod u strojarstvu se danas odnosi i na projektiranje i na stvarnu izradu tog proizvoda. ProEngineer, kao osnovni softver ovoga rada je, sa svojim interaktivno povezanim modulima, potpuno funkcionalan alat za rješavanje i najsloženijih strojarskih zadataka u prihvatljivom vremenskom razmaku. Pojam prihvatljivog vremena proizvodnje i izrade proizvoda uključuje rješavanje problema s ciljem dobivanja finalnog proizvoda, bilo kojeg oblika, uz optimiziranje svih stadija planiranja, analize, razvoja i proizvodnje. Brzina rješavanja konstrukcijskog zadatka je uvjet postojanja profitabilne proizvodnje u strojarstvu, a ovaj bi rad to trebao dokazati. Ranije je rečeno da je ovaj rad zasnovan na primjeni interaktivno povezanih modula softvera za konstruiranje ljevačkog panela za ubrizgani plastični zupčanik.The current technological level of mechanical engineering sequentially requires an active software application in all construction stages of certain mechanical projects – products. When we say product today in engineering we refer to the design of a product, as well as to the actual construction. ProEngineer, as basic software of this thesis, with its interactively connected modules, is a completely functional tool for solving even the most complex tasks of mechanical engineering in acceptable time frame. The notion of acceptable construction time frame and mechanical design production includes problem solving aiming at constructing the final product, in any shape, tending to optimize all stages of planning, analysis, development and production. The speed of construction task solving conditions the existence of profitable production in mechanical engineering, which should be proved through the work under this title. It is said previously that the foundation of this thesis is the application of interactively joined software modules for constructing a casting panel for injected plastic gear wheel

Expected accuracy of tilt measurements on a novel hexapod-based Digital zenith camera system: A Monte-Carlo simulation study

Digital zenith camera systems (DZCS) are dedicated astronomical-geodetic measurement systems for the observation of the direction of the plumb line. A DZCS key component is a pair of tilt meters for the determination of the instrumental tilt with respect to the plumb line. Highest accuracy (i.e., 0.1 arc-seconds or better) is achieved in practice through observation with precision tilt meters in opposite faces (180° instrumental rotation), and application of rigorous tilt reduction models. A novel concept proposes the development of a hexapod (Stewart platform)-based DZCS. However, hexapod-based total rotations are limited to about 30°–60° in azimuth (equivalent to ±15° to ±30° yaw rotation), which raises the question of the impact of the rotation angle between the two faces on the accuracy of the tilt measurement. The goal of the present study is the investigation of the expected accuracy of tilt measurements to be carried out on future hexapod-based DZCS, with special focus placed on the role of the limited rotation angle. A Monte-Carlo simulation study is carried out in order to derive accuracy estimates for the tilt determination as a function of several input parameters, and the results are validated against analytical error propagation.As the main result of the study, limitation of the instrumental rotation to 60° (30°) deteriorates the tilt accuracy by a factor of about 2 (4) compared to a 180° rotation between the faces. Nonetheless, a tilt accuracy at the 0.1 arc-second level is expected when the rotation is at least 45°, and 0.05 arc-second (about 0.25 microradian) accurate tilt meters are deployed. As such, a hexapod-based DZCS can be expected to allow sufficiently accurate determination of the instrumental tilt. This provides supporting evidence for the feasibility of such a novel instrumentation. The outcomes of our study are not only relevant to the field of DZCS, but also to all other types of instruments where the instrumental tilt must be corrected. Examples include electronic theodolites or total stations, gravity meters, and other hexapod-based telescopes

Depression Symptoms in Haemodialysis Patients Predict All-Cause Mortality but Not Kidney Transplantation: A Cause-Specific Outcome Analysis

Background:Depression is common in haemodialysis (HD) patients and associated with poor outcomes. Purpose:To evaluate whether depression symptoms predict survival and transplantation in a large sample of haemodialysis patients using cause-specific survival models. Methods:Survival data was collected between April 2013 and November 2015, as part of the screening phase of a multicentre randomised placebo-controlled trial of sertraline in HD patients. Depression was measured using the Beck Depression Inventory-II (BDI-II) and the Patient Health Questionnaire-9 (PHQ-9). Demographic and clinical data were collected via a self-report questionnaire and medical records. Competing risk survival analysis involved cause-specific and subdistribution hazard survival models. All models were adjusted for appropriate covariates including co-morbidity and C-reactive protein (CRP) in a subanalysis. Results:Of 707 cases available for analysis, there were 148 deaths. The mean survival time was 787.5 days. Cumulative survival at 12 months was 88.5%. During the study follow-up period, there were 92 transplants. The cumulative transplant event rate at 12 months was 7.8%. In separate adjusted models, depression symptoms predicted mortality (BDI-II HR = 1.03 95% CI 1.01, 1.04; PHQ-9 HR = 1.04 95% CI 1.01, 1.06). With respect to screening cut-off scores, a PHQ-9 ≥ 10 was associated with mortality (HR = 1.51 95% CI 1.01, 2.19) but not a BDI-II ≥ 16. Depression symptoms were not associated with time to transplantation in either cause-specific or subdistribution model. Conclusions:Consistent with past findings in HD patients, depression symptoms predicted survival but were not associated with kidney transplantation. Suitable treatments for depression need further evaluation, and their impact upon quality of life and clinical outcomes determined. Trial Registration Number:(ISRCTN06146268)

Influence of GPS measurements quality to NTP time-keeping

Peer Reviewe