1,804 research outputs found
Nadere verfijning DUROSTA-model: Toetsing H/Tw-parameter en aanpassing t.b.v. porositeitsverschillen en strandtransporten
No full textTeneinde het DUROSTA-model verder te verbeteren zijn de effecten modellering nader onderzocht en is de schaalgrootheid H/Tw nader bekeken.TAW/EN
Development of a rotor model for the numerical simulation of helicopter exterior flow-fields
No full textIncludes bibliographical references (leaves 84-85).A numerical methodology is developed to model the effect of a rotor on the surrounding flow-field. The model calculates the time-averaged aerodynamic forces exerted on the air by the fan blades within the blade-swept region, and permits the user to specify blade properties such as cross-sectional profile and orientation at a particular radial and azimuthal location. The calculated forces are included as source terms within the Reynolds-averaged Navier-Stokes equations for an incompressible fluid, which are solved by the commercial CFD solver, FLUENT. The effects of turbulence are incorporated through the use of Launder and Spalding's k-g turbulence model. This method is selected as being the most efficient use of the resources available, giving the economic advantages of a steady simulation, while allowing radial and azimuthal variations of rotor characteristics. In order to validate the accuracy of the numerical model for both aligned and non-aligned inflow conditions, results are compared with experimental data reported for an axial flow fan. Agreement between experimental and numerical results is excellent to good. Fan static pressure rise is closely predicted by the numerical solution, while fan power consumption and fan static efficiency are under and over-predicted respectively. This error may be attributed to frictional losses not accounted for in the numerical model. These include physical rotational instabilities, leading to increased mechanical losses, and tip effects due to the clearance between the fan blade tips and the fan casing. Trends are nevertheless consistently predicted by the numerical model for inflow angles up to 45°, and for the range of blade pitch settings used. The adverse effect of off-axis inflow on the fan static pressure rise is numerically predicted, while fan power consumption is found to remain independent of inflow angle, as had been experimentally observed. The rotor model is finally integrated with the fuselage of the CIRSTEL (Combined Infra-Red Suppression and Tail rotor Elimination) prototype in an analysis of the helicopter exterior flow-field. No experimental data for this configuration was available for validation purposes. However, the model is used in the simulation of several common helicopter flight conditions. Results are presented graphically, and generally indicate good agreement with physically observed phenomena
Third body effects in the period changes of two Algol binaries: V342 Aql and TW Lac
No full text32nd International Physics Congress of Turkish-Physical-Society (TPS) -- SEP 06-09, 2016 -- Bodrum, TURKEYThe O - C diagrams of two Algol-type eclipsing binaries V342 Aql and TW Lac have been analyzed with the least-squares method by using all available minima times. The period changes in their O - C diagrams have been discussed with respect to the Light-Time Effect (LITE) that originates from gravitational influence of a third body. New LITE elements, orbital periods and possible minimum masses of third bodies are given.Turkish Phys So
Increasing science, technology, engineering, and mathematics skills using Project Lead the Way
No full textIncludes bibliographical references
Psychological, social and welfare interventions for psychological health and well-being of torture survivors
No full textThis is the protocol for a review and there is no abstract. The objectives are as follows: Primary objective 1. To assess beneficial and adverse effects of psychological, social and welfare interventions versus no treatment for the reduction of psychological distress in torture survivors. Secondary objectives 2. To describe the quality and generalisability of the studies evaluating the effects of these treatment approaches on torture survivors, and specifically: • to provide an objective assessment of risk of bias in these studies; • to describe the specific populations evaluated in studies of torture survivors (including demographics, torture experiences and psychological status); • to describe the variety of interventions that have been evaluated in these populations; and • to describe the outcomes evaluated in these intervention studies
High-efficiency supercontinuum generation in solid thin plates at 0.1 TW level
No full text
Supercontinuum generation in a solid-state medium was investigated experimentally. A continuum covering 460 to 950 nm was obtained when 0.8 mJ/30 fs Ti: sapphire laser pulses were applied to seven thin fused silica plates at a 1 kHz repetition rate. The primary processes responsible for spectral broadening were self-phase modulation (SPM) and self-steepening, while SPM and self-focusing were balanced to optimize the spectral broadening and suppress the multi-photon process. The output was compressed to a 5.4 fs and a 0.68 mJ pulse, corresponding to two optical cycles and 0.13 TW of peak power. (C) 2017 Optical Society of America</p
Flow compensation in a MEMS dual-thermal conductivity detector for hydrogen sensing in natural gas
No full textConventional thermal conductivity detectors (TCDs) demonstrate a flow dependence. The approach presented here to reduce the flow dependence is based on the on-line flow compensation using two thin-film sensors on membranes in parallel on the same chip that are differentially operated. These are laterally identically, but with a different depth of the detection chamber, resulting in different quasi-static sensitivities to the thermal conductivity of the sample gas. The effects of conduction and convection in the structure have been studied using COMSOL Multiphysics. First prototypes have been fabricated and are presently tested.Accepted Author ManuscriptElectronic Instrumentatio
Obesity-Related Disorders in Türkiye: A Multi Center, Retrospective, Cross-Sectional Analysis from the OBREDI-TR Study
No full textfirst_pagesettingsOrder Article ReprintsOpen AccessArticleObesity-Related Disorders in Türkiye: A Multi Center, Retrospective, Cross-Sectional Analysis from the OBREDI-TR StudySave<button class="flex cursor-pointer items-center justify-center gap-2 font-sans text-sm font-semibold focus-visible:outline-none disabled:pointer-events-none disabled:opacity-40 disabled:hover:pointer-events-auto border border-solid bg-transparent bg-secondary-500 disabled:text-secondary-400 px-2 py-1 rounded-md border-secondary-500 bg-transparent text-secondary-500 hover:border-secondary-600 hover:text-secondary-600 whitespace-nowrap rounded-md !border-neutral-100 font-sans !font-medium transition-all hover:bg-blue-50 hover:text-secondary-500 bg-white" type="button" aria-haspopup="dialog" aria-expanded="false" aria-controls="radix-:r1:" data-state="closed" style="--tw-border-spacing-x: 0; --tw-border-spacing-y: 0; --tw-translate-x: 0; --tw-translate-y: 0; --tw-rotate: 0; --tw-skew-x: 0; --tw-skew-y: 0; --tw-scale-x: 1; --tw-scale-y: 1; --tw-pan-x: ; --tw-pan-y: ; --tw-pinch-zoom: ; --tw-scroll-snap-strictness: proximity; --tw-gradient-from-position: ; --tw-gradient-via-position: ; --tw-gradient-to-position: ; --tw-ordinal: ; --tw-slashed-zero: ; --tw-numeric-figure: ; --tw-numeric-spacing: ; --tw-numeric-fraction: ; --tw-ring-inset: ; --tw-ring-offset-width: 0px; --tw-ring-offset-color: #fff; --tw-ring-color: rgba(59,130,246,.5); --tw-ring-offset-shadow: 0 0 transparent; --tw-ring-shadow: 0 0 transparent; --tw-shadow: 0 0 transparent; --tw-shadow-colored: 0 0 transparent; --tw-blur: ; --tw-brightness: ; --tw-contrast: ; --tw-grayscale: ; --tw-hue-rotate: ; --tw-invert: ; --tw-saturate: ; --tw-sepia: ; --tw-drop-shadow: ; --tw-backdrop-blur: ; --tw-backdrop-brightness: ; --tw-backdrop-contrast: ; --tw-backdrop-grayscale: ; --tw-backdrop-hue-rotate: ; --tw-backdrop-invert: ; --tw-backdrop-opacity: ; --tw-backdrop-saturate: ; --tw-backdrop-sepia: ; display: flex; align-items: center; justify-content: center; gap: 8px; text-wrap-mode: nowrap; border-radius: 0.375rem; border-width: 1px; border-style: solid; --tw-border-opacity: 1; border-color: rgb(4, 123, 178); --tw-bg-opacity: 1; backgr
Effect of Mg doing on microstructure and dielectric properties of barium strontium titanate ceramics
No full textA comparative study of viscous polymer processed ceramics based on aqueous and non-aqueous binder systems
No full textLead zirconate titanate (PZT) is an important piezoelectric material which has wide range of applications as sensors, actuators and transducers. Various forms are required for different devices applications. In this work, extrusion and press forming of PZT ceramic rods and thick films produced via a viscous polymer processing (VPP) route have been investigated. The relationships between the rheology, microstructure and formability of both an aqueous and a non-aqueous polymer binder system have been compared. The non-aqueous PVB system exhibits substantially higher bulk yield stress during plug die flow and higher biaxial extensional stress during squeeze film flow compared to the aqueous PVA system. Discussion of the results is based on differences in the adsorption of the polymer onto the PZT particles and the migration behaviour of the polymer/solvent phase in the two systems. (C) 2008 Elsevier B.V. All rights reserved
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