Collection Efficiencies Greater Than Unity by Electron Or Hole Gating in a-Si:H p-i-n Diodes

1999 ◽  
Vol 557 ◽  
Author(s):  
J.-H. Zollondz ◽  
C. Main ◽  
S. Reynolds
Keyword(s):  
Probe Beam ◽  
Reverse Bias ◽  
Collection Efficiency ◽  
Simulated Data ◽  
Measured Data ◽  
Lower Mobility ◽  
Electron Gating ◽  
Very High ◽  
Side Bias

AbstractWe report measured electron and hole gating in thick a-Si:H (3.5 μm) p-i-n diodes under reverse bias conditions. Previous publications have shown very high collection efficiency values for electron gating (p-side bias, n-side probe) of up to 50 (i.e. 5000%) for measured and simulated data and predictions of up to 400 (i.e. 40000%) from simulations. Reversing the usual sides of illumination for (electron) gating a situation can be created where, by n-side bias and p-side probe illumination, holes can be gated to travel through the sample to be collected at the contact. Even though the holes have much lower mobility, by this process we can still obtain collection efficiencies greater than unity. This measurement is more difficult because of unwanted illumination by stray bias beam photons on the more sensitive p-side, caused by reflections within the apparatus. Simulation of this situation corroborates qualitatively the measured data. A wide ranging study of the gating phenomenon in relation to different incident wavelengths and photon fluxes for bias and probe beam is reported. We present comparisons of electron and hole gating by measurement and simulation and explain the phenomenon for both electron and hole gating in terms of field changes near to the incident bias interface.

scholarly journals How to Get Component Maps for Aircraft Gas Turbine Performance Calculations

1996 ◽  
Author(s):  
Joachim Kurzke
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Measured Data ◽  
Turbine Performance ◽  
The Many ◽  
Map Data ◽  
Performance Calculation ◽  
Excellent Tool ◽  
Very High ◽  
Drawing Program

Precise simulations of gas turbine performance cannot be done without component maps. In the early days of a new project one often has to use scaled maps of similar machines. Alternatively one can calculate the component partload characteristics provided that the many details needed for such an exercise are available. In a later stage often rig tests will be done to get detailed information about the behavior of the compressors respectively turbines. Performance calculation programs usually require the map data in a specific format. To produce this format needs some preprocessing. Measured data cannot be used directly because they show a scatter and they are not evenly distributed over the range of interest. Due to limitations in the test equipment often there is lack of data for very low and very high speed. With the help of a specialized drawing program available on a PC one can easily eliminate the scatter in the data and also inter- and extrapolate additional lines of constant corrected speed. Many graphs showing both the measured data and the lines passing through the data as a function of physically meaningful parameters allow to check whether the result makes sense or not. The extrapolation of compressor maps toward very low speed, as required for the calculation of starting, idle and windmilling performance calculations, is discussed in some detail. Instead of true measured data one can use data read from maps published in open literature. The program is also an excellent tool for checking and extending component maps one has derived from sparse information about a gas turbine to be simulated.

scholarly journals Securing of an Industrial Soil Using Turfgrass Assisted by Biostimulants and Compost Amendment

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1310 ◽  
Author(s):  
Donato Visconti ◽  
Antonio Giandonato Caporale ◽  
Ludovico Pontoni ◽  
Valeria Ventorino ◽  
Massimo Fagnano ◽  
...  
Keyword(s):  
Festuca Arundinacea ◽  
Poa Pratensis ◽  
Grass Species ◽  
Ammonia Oxidizing Bacteria ◽  
Industrial Sites ◽  
Industrial Soil ◽  
Compost Amendment ◽  
Lower Mobility ◽  
Dactylis Glomerata L ◽  
Very High

This work aimed to study the effects of compost (applied at two rates) and two commercial microbial biostimulants on the mobility and bioavailability of potentially toxic elements (PTEs) in an industrial soil phytostabilized by Dactylis glomerata L. or a mixed stand of grasses (Lolium perenne L., Poa pratensis L. and Festuca arundinacea Shreb.). The soil showed very high pseudototal and bioavailable concentrations of cadmium (Cd) and lead (Pb), due to improper lead-acid batteries storage. Compost amendment in combination with the two biostimulants produced the best outcomes in terms of plant growth and nutrient uptake. The same mix of beneficial microbes improved soil biological fertility enhancing soil nitrogen fixing and ammonia oxidizing bacteria, while reduced the pore water and NH4NO3 extractable concentrations of Cd and at lower extent of Pb in soil. Accordingly, the lower mobility and bioavailability of Cd in soil determined a lower uptake and accumulation of Cd in shoots of different grass species. Our results suggest that a green cap with turfgrass assisted by biostimulants and compost amendment in PTE-contaminated industrial sites could be a reliable and effective practice to protect and restore soil biological fertility and to reduce the risk of PTE dispersion in the surrounding environment.

Validating a Single-Phase Flow Pipeline Simulation Model Against Real Data From a Vapor Collapse Event

2018 ◽  
Author(s):  
Ulli Pietsch ◽  
Hanna Sieben
Keyword(s):  
Data Acquisition ◽  
Simulated Data ◽  
Large Change ◽  
Measured Data ◽  
Simulation Software ◽  
Operating Conditions ◽  
Pressure Data ◽  
Hydraulic Conditions ◽  
Pipeline Segment ◽  
Pressure Surge

Transient hydraulic conditions during a shutdown and subsequent start-up of a segment of a pipeline that runs through a mountainous region were simulated using commercially available hydraulic simulation software and a model of the relevant portion of the pipeline facilities. The segment of interest is located in an area where the pipeline is normally operated with vapor present (slack line flow conditions) due to the large change in elevation. Pressure data that was recorded by the pipeline’s data acquisition system indicated a pressure surge occurred when the line was restarted. The suspected cause of this pressure surge was the collapse of the vapor in this pipeline segment. Beginning with an estimate of the flow, pressure and temperature data for the pipeline segment at steady state conditions prior to the shutdown, the simulation was tuned to reasonably match the measured data. The resulting simulated data closely replicated the surge event. Examination of the simulated data provides insights into the hydraulic conditions in the pipeline at locations where pressure data is not measured, as well as during the time intervals between data acquisition scans. It also reveals impact of the timing of the mainline valve opening sequence. Further, since the simulated data does accurately replicate the actual measured data, the model can be used to evaluate how changes to facilities or operating conditions impact the formation and the collapse of vapor in this pipeline segment.

Ship As a Wave Buoy: Using Simulated Data to Train Neural Networks for Real Time Estimation of Relative Wave Direction

2019 ◽  
Author(s):  
Bart Mak ◽  
Bülent Düz
Keyword(s):  
Neural Networks ◽  
Real Time ◽  
General Model ◽  
Simulated Data ◽  
Time Estimation ◽  
Measured Data ◽  
Wave Direction ◽  
Sea State ◽  
Digital Twin ◽  
Extended Training

Abstract Being able to give real time on-board advice, without depending on extensive sets of measured data, is the ultimate goal of the digital twin concept. Ideally, the models used in a digital twin only rely on current in-service data, although they have been built using simulated and possibly some measured data. Working with just the 6-DOF motions of a ship, can the local sea state reliably be estimated using the digital twin concept? Does a general model exist to do so, without the need to measure or simulate the particular ship? In this paper, we discuss how simulations of an advancing ship, subjected to various sea states, can be used to estimate the relative wave direction from in-service motion measurements of the corresponding ship. Various types of neural networks are used and evaluated with simulated data and measured data. In order to study the generalization power of the neural networks, a range of ships has been simulated, with varying lengths, drafts and geometries. Neural networks have been trained on selections of the ships in this extended training set and evaluated on the remaining ships. Results show that the developed neural networks give a remarkable performance in simulation data. Furthermore, generalization over geometry is very good, opening the door to train a general model for estimating sea state characteristics. Using the same model for in-service measurements does not perform well enough yet and further research is required. The paper will include discussion on possible causes for this performance gap and some promising ideas for future work.

Analysing the correlation between vehicle responses and track irregularities using dynamic simulations and measurements

2019 ◽  
Vol 234 (2) ◽  
pp. 170-182 ◽  
Author(s):  
Tomas Karis ◽  
Mats Berg ◽  
Sebastian Stichel
Keyword(s):  
Simulated Data ◽  
Measured Data ◽  
Statistical Characteristics ◽  
Acceptance Testing ◽  
Dynamic Simulations ◽  
Track Maintenance ◽  
Track Stiffness ◽  
Suspension Stiffness ◽  
Unsprung Mass ◽  
Track Irregularities

Track irregularities play a key role in vehicle response, but it is not uncommon to find irregularities with similar statistical characteristics giving very different vehicle behaviour. It is therefore important to find a consistent way of describing track irregularities, which better matches the vehicle behaviour to facilitate an efficient track maintenance and vehicle acceptance testing. Various proposals have been made to resolve this issue, although with limited success. In the present paper, a methodology to break down the track–vehicle interaction into steps, by analysing the irregularity–response correlation in detail, is applied to both the measured and simulated data of a passenger coach. The results show a very good agreement and a high correlation coefficient between the vertical axle box acceleration and the second spatial derivative of the vertical track irregularities when analysing the simulated data, but not for the measured data. Parameter variations are carried out through simulations, in which the vertical track stiffness, vehicle unsprung mass, vertical primary suspension and different combinations of track irregularities are varied. The results show that track stiffness mainly affects the axle box acceleration whereas the primary vertical suspension stiffness and unsprung mass predominantly affect the vertical wheel–rail forces. Therefore, it is important to understand the influence of track stiffness, especially with the help of the measured data, and the methods that reduce its influence should be investigated in future works.

Effects of Very High Neutron Fluence Irradiation on p+n Junction 4H-SiC Diodes

2007 ◽  
Vol 556-557 ◽  
pp. 917-920 ◽  
Author(s):  
Francesco Moscatelli ◽  
Andrea Scorzoni ◽  
Antonella Poggi ◽  
Mara Passini ◽  
Giulio Pizzocchero ◽  
...  
Keyword(s):  
Leakage Current ◽  
Leakage Current Density ◽  
Current Density ◽  
Reverse Bias ◽  
Neutron Fluence ◽  
Signal To Noise Ratio ◽  
Reverse Current ◽  
Low Noise ◽  
High Signal ◽  
Very High

In this work we analyzed the radiation hardness of SiC p+n diodes after very high 1 MeV neutron fluence. The diode structure is based on a p+ emitter ion implanted in n-type epilayer with thickness equal to 5 %m and donor doping ND = 3×1015 cm-3. Before irradiation, the average leakage current density at 100 V reverse bias was of the order of 3 nA/cm2. These devices were irradiated at four different fluence values, logarithmically distributed in the range 1014-1016 (1 MeV) neutrons/cm2. After irradiation the epilayer material became more resistive, as indicated by the reduction of the forward and reverse current density at a given voltage. In particular, after a neutron fluence of 1×1014 n/cm2 the epilayer active doping concentration decreased to 1.5×1015 cm-3. After irradiation at 1016 n/cm2, i.e. the highest fluence value, the average leakage current density at 100 V reverse bias decreased to values of the order of 0.1 nA/cm2. This very low noise even after very high fluence is very important to obtain a high signal to noise ratio even at room temperature.

A Data-Constrained 3D Model for Material Compositional Microstructures

2008 ◽  
Vol 32 ◽  
pp. 267-270 ◽  
Author(s):  
Sam Yang ◽  
Scott Furman ◽  
Andrew Tulloh
Keyword(s):  
Mathematical Model ◽  
Material Properties ◽  
Reasonable Agreement ◽  
3D Model ◽  
Compositional Data ◽  
Simulated Data ◽  
Measured Data ◽  
Porosity Distribution ◽  
Numerical Predictions ◽  
Tomography Data

A mathematical model has been developed for predicting material compositional microstructures using measured data as constraints. Examples of measured data include 3-D sets of tomography data, 2-D sets of compositional data on surfaces and sections, and material absorption and interaction properties. The model has been partially implemented as a MS-Windows application. Reasonable agreement has been obtained between the numerical predictions from the software and the simulated data. The predicted microstructures could be used to study various material properties such as porosity distribution, diffusion and corrosion.

scholarly journals Patch Antenna Based on MUC for Wi-Fi and 5G

2021 ◽  
Author(s):  
Suman Nelaturi ◽  
Nookala Venkata Satya Narasimha Sarma
Keyword(s):  
Circular Polarization ◽  
Frequency Band ◽  
Transmission Lines ◽  
Patch Antenna ◽  
Simulated Data ◽  
Measured Data ◽  
Unit Cell ◽  
Dual Band ◽  
Double Negative ◽  
Fractal Boundary

This communication reported the patch antenna working at Wi-Fi and 5G bands. To acquire compactness the side lengths of the patch are taken based on upper-frequency band (3.3 GHz). Dual-band operation (lower resonating band) is realized by loading the Mushroom Unit Cell (MUC) along the bottom right corner of the patch. To obtain Circular Polarization (CP) at the 5G band the conventional patch is modified with fractal boundary. This blend of the Double Negative Transmission Lines metamaterials (DNG TL), as well as fractal concepts yielded good compactness suitable for ultra-thin portable gadgets. Measured results have good correlation with simulated data from HFSS. The obtained bandwidths at the lower and upper bands are 2.51 % and 6.23 % when the Poly fractal curves are introduced. CP bandwidth of the proposed antenna at 5G band obtained from the measured data is 2.35 % which is the highest to the best of authors' knowledge for this type of thin antennas.

Identification of Loads on Suspenders in Bridges Based on Measured Response Data in Time Domain

2012 ◽  
Vol 226-228 ◽  
pp. 1640-1644
Author(s):  
Li Tao Zhang ◽  
Yu Feng Zhang
Keyword(s):  
Differential Equation ◽  
Time Domain ◽  
Simulated Data ◽  
Measured Data ◽  
Superposition Method ◽  
Acceleration Response ◽  
Regularization Technique ◽  
Response Data ◽  
Tied Arch Bridge ◽  
Measured Response

The purpose of this paper is to deal with identification of loads on suspenders. Values of the load at every moment were chose as identification parameters, and the objective function was established using measured data of responses and corresponding simulated ones. The vibration differential equation of suspenders was adopted to obtain the formula of relationship between the load and acceleration responses with superposition method. Furthermore, a regularization technique was applied in identification calculations to improve ill-posedness of the problem to be solved. With a tied arch bridge as the real example, the load on one of its suspenders was identified. Results of identification showed that the simulated data of acceleration response were almost identical to measured ones, which indicated validity of the proposed method.

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