scholarly journals Regimes of radiative and nonradiative transitions in transport through an electronic system in a photon cavity reaching a steady state

2016 ◽  
Vol 529 (1-2) ◽  
pp. 1600177 ◽  
Author(s):  
Vidar Gudmundsson ◽  
Thorsteinn H. Jonsson ◽  
Maria Laura Bernodusson ◽  
Nzar Rauf Abdullah ◽  
Anna Sitek ◽  
...  
Keyword(s):  
Steady State ◽  
Electronic System ◽  
Nonradiative Transitions

Transient Numerical Computation of the Temperature of Electronic Devices in Passenger Cars: Flow Simulation in Electronics Cavities

2010 ◽  
Author(s):  
Florence Michel ◽  
Bernard Desmet
Keyword(s):  
Steady State ◽  
Turbulence Modeling ◽  
Numerical Models ◽  
Flow Simulation ◽  
Electronic System ◽  
Time Dependent ◽  
Passenger Cars ◽  
Multi Scale ◽  
Coupled Heat Transfer ◽  
Steady State Method

To compute the temperature of an electronic system submitted to time-dependent thermal loads, the problem of multi-scale coupled heat transfer modes is solved by means of co-simulation strategies. These coupling strategies use adapted codes for the prediction of each transfer mode, e.g. a CFD code for the computation of convection and a FE code for conduction. In this paper, numerical models to solve the flow in typical electronic enclosures are investigated, in particular regarding mesh requirements and turbulence modeling. First, the accuracy of a steady-state approach for the computation of natural convection in a cavity heated from below is examined for a large range of Rayleigh number covering time-dependent convection. Then, a steady-state method for fan flow simulation is presented and validated in comparison with the fan performance curve measured in a test-rig. Finally, different numerical models for flow computation through thin grills of an electronic system are discussed regarding the fan mass flow rate and the establishing pressure distribution.

Automatic System for Wind Turbine Testing

2001 ◽  
Vol 123 (4) ◽  
pp. 333-338 ◽  
Author(s):  
S. M. Camporeale ◽  
B. Fortunato ◽  
G. Marilli
Keyword(s):  
Control System ◽  
Steady State ◽  
Wind Turbine ◽  
Performance Test ◽  
Electronic System ◽  
Fine Tuning ◽  
Electronic Control ◽  
Automatic Data ◽  
Electric Generator ◽  
Pulse Width Modulator

An innovative electronic system for testing the performance of wind turbines is presented. The main goal of the system is to increase the accuracy in the measurements of torque and speed for each steady-state point of the turbine characteristic power curve. Another useful advantage provided by the electronic control is given by the possibility of fine tuning the load in order to obtain a large number of steady state experimental points describing the characteristic curve of the turbine. Moreover, the system is suitable for integration into an automatic data acquisition and control system. In the paper the main characteristics of the electronic system are described and compared with a traditional system. This electronic control system is used for testing a small Vertical Axis Wind Turbine in a wind tunnel. The wind turbine is directly coupled to a direct current electric generator, and a chopper, electronically controlled by means of a Pulse Width Modulator, is used to supply the circuit. The electric generator is used for braking the wind turbine at various speeds during the performance test. The experimental results obtained through the proposed system are presented and discussed.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Representation of information in SEM by equal signal lines

1978 ◽  
Vol 36 (1) ◽  
pp. 144-145
Author(s):  
E. Rau ◽  
N. Karelin ◽  
V. Dukov ◽  
M. Kolomeytsev ◽  
S. Gavrikov ◽  
...  
Keyword(s):  
Electronic System ◽  
Space Distribution ◽  
Specimen Surface ◽  
Universal Method ◽  
Base Level ◽  
Signal Value ◽  
Information Signal ◽  
Fixed Base ◽  
Scanning Line ◽  
Amplitude Analyzer

There are different methods and devices for the increase of the videosignal information in SEM. For example, with the help of special pure electronic [1] and opto-electronic [2] systems equipotential areas on the specimen surface in SEM were obtained. This report generalizes quantitative universal method for space distribution representation of research specimen parameter by contour equal signal lines. The method is based on principle of comparison of information signal value with the fixed levels.Transformation image system for obtaining equal signal lines maps was developed in two versions:1)In pure electronic system [3] it is necessary to compare signal U (see Fig.1-a), which gives potential distribution on specimen surface along each scanning line with fixed base level signals εifor obtaining quantitative equipotential information on solid state surface. The amplitude analyzer-comparator gives flare sport videopulses at any fixed coordinate and any instant time when initial signal U is equal to one of the base level signals ε.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

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