A Digital Holographic Approach for Co-Phasing of Segmented Telescopes: Proof of Concept Using Numerical Simulations

2014 ◽  
Vol 126 (937) ◽  
pp. 280-286 ◽  
Author(s):  
Changwei Li ◽  
Sijiong Zhang
Keyword(s):  
Numerical Simulations ◽  
Proof Of Concept ◽  
Holographic Approach

EVALUATION OF LEFT VENTRICULAR FILLING PRESSURE USING NUMERICAL MODELING

2020 ◽  
Vol 20 (07) ◽  
pp. 2050043
Author(s):  
A. BENFOULA ◽  
L. HAMZA CHERIF ◽  
K. N. HAKKOUM
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Left Ventricle ◽  
Numerical Simulations ◽  
Left Ventricular ◽  
Filling Pressure ◽  
Proof Of Concept ◽  
Ventricular Dilation ◽  
Ventricular Filling Pressure ◽  
Ventricular Filling

The main objective of this work is to study the effect of blood pressure and viscosity on flow in a pathological and healthy anatomy. The method chosen for this project is the numerical simulation of fluid dynamics. First, a radiological database from Tlemcen hospital was studied in order to select a patient whose aortic anatomy is representative of the pathology studied in this research project. The left ventricle was segmented using SolidWork software. The exported data made it possible to model this geometry on Comsol software. The geometry has been idealized to make it comparable to a given healthy left ventricle geometry and present the main parameters which influence the ventricular hemodynamics. A first series of numerical simulations made it possible to highlight the hemodynamic disturbances associated with the pathology of interest and described extensively in the literature. A second series of numerical simulations made it possible to model the effect of blood viscosity on flow. All the results obtained, the modeling of the left ventricle, must be valid experimentally. This study therefore does not completely justify the treatment of ventricular dilation with a flow modulator but constitutes an important first step towards a proof of concept.

Direct measurement of electron-diffraction-pattern intensities using an energy loss spectrometer

1989 ◽  
Vol 47 ◽  
pp. 668-669
Author(s):  
A. G. Jackson ◽  
M. Rowe
Keyword(s):  
Thermal Effects ◽  
Dynamic Range ◽  
Scattering Amplitude ◽  
Dynamical Theory ◽  
Site Symmetry ◽  
Proof Of Concept ◽  
Parallel Acquisition ◽  
Kinematic Approximation ◽  
Speed Up ◽  
Structure Calculations

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

Remote Echocardiography: Proof of Concept for Support of National Disasters, Combat and Humanitarian Mission

2002 ◽  
Author(s):  
Sheri Yvonne Nottestad Boyd ◽  
Linda L. Huffer ◽  
Terry D. Bauch ◽  
James L. Furgerson
Keyword(s):  
Proof Of Concept ◽  
Humanitarian Mission

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

Model, simulation and experiments for a Buoyancy Organic Rankine Cycle

2020 ◽  
Vol 92 (1) ◽  
pp. 10906
Author(s):  
Jeroen Schoenmaker ◽  
Pâmella Gonçalves Martins ◽  
Guilherme Corsi Miranda da Silva ◽  
Julio Carlos Teixeira
Keyword(s):  
Model Simulation ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Test Body ◽  
Working Fluid ◽  
Proof Of Concept ◽  
Energy Scenario ◽  
New Type ◽  
Fluid Reservoir

Organic Rankine Cycle (ORC) systems are increasingly gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organic Rankine Cycle (BORC) [J. Schoenmaker, J.F.Q. Rey, K.R. Pirota, Renew. Energy 36, 999 (2011)]. In this work we present two main contributions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dichloromethane at temperatures up to 100 °C were estimated to be 17.2%. Second, we show a proof of concept BORC system using a 3 m tall, 0.062 m diameter polycarbonate tube as a column-fluid reservoir. We used water as a column fluid. The thermal stability and uniformity throughout the tube has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessment of the BORC-system's efficiency. We obtained 0.84% efficiency for 43.8 °C working temperature. This corresponds to 35% of the Carnot efficiency calculated for the same temperature difference. Limitations of the model and the apparatus are put into perspective, pointing directions for further developments of BORC systems.

Indocyanine green-augmented diode laser therapy of telangiectatic and reticular leg veins: a clinical proof-of-concept trial

2012 ◽  
Vol 25 (01) ◽  
Author(s):  
A Klein ◽  
G Shafirstein ◽  
E Kohl ◽  
W Bäumler ◽  
M Landthaler ◽  
...  
Keyword(s):  
Indocyanine Green ◽  
Laser Therapy ◽  
Diode Laser ◽  
Proof Of Concept
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