Device Modeling of a-Si:H Alloy Solar Cells: Calibration Procedure for Determination of Model Input Parameters

1998 ◽  
Vol 507 ◽  
Author(s):  
M. Zeman ◽  
R.A.C.M.M. Van Swaaij ◽  
E. Schroten ◽  
L.L.A. Vosteen ◽  
J.W. Metselaar
Keyword(s):  
Solar Cell ◽  
Material Properties ◽  
Calibration Procedure ◽  
Model Parameters ◽  
Model Input ◽  
A Value ◽  
Input Parameters ◽  
Simulated Material ◽  
Good Agreement

ABSTRACTA calibration procedure for determining the model input parameters of standard a-Si:H layers, which comprise a single junction a-Si:H solar cell, is presented. The calibration procedure consists of: i) deposition of the separate layers, ii) measurement of the material properties, iii) fitting the model parameters to match the measured properties, iv) simulation of test devices and comparison with experimental results. The inverse modeling procedure was used to extract values of the most influential model parameters by fitting the simulated material properties to the measured ones. In case of doped layers the extracted values of the characteristic energies of exponentially decaying tail states are much higher than the values reported in literature. Using the extracted values of model parameters a good agreement between the measured and calculated characteristics of a reference solar cell was reached. The presented procedure could not solve directly an important issue concerning a value of the mobility gap in a-Si:H alloys.

Development of a Stochastic Approach for Vehicle FE Models

2003 ◽  
Author(s):  
David Riha ◽  
Joseph Hassan ◽  
Marlon Forrest ◽  
Ke Ding
Keyword(s):  
Finite Element ◽  
Reliability Analysis ◽  
System Reliability ◽  
Model Parameters ◽  
Fe Model ◽  
Original Design ◽  
Acceptance Criteria ◽  
Model Input ◽  
Input Parameters ◽  
Occupant Injury

This paper describes the development of a mathematical model capable of providing realistic simulations of vehicle crashes by accounting for uncertainty in the model input parameters. The approach taken was to couple advanced and efficient probabilistic and reliability analysis methods with well-established, high fidelity finite element and occupant modeling software. Southwest Research Institute has developed probabilistic analysis software called NESSUS. This code was used as the framework for a stochastic crashworthiness FE model. The LS-DYNA finite element model of vehicle frontal offset impact and the MADYMO model of a 50th percentile male Hybrid III dummy were integrated with NESSUS to comprise the crashworthiness characteristics. The system reliability of the vehicle is computed by defining ten acceptance criteria performance functions; four occupant injury criteria and six compartment intrusion criteria. The reliability for each acceptance criteria was computed using NESSUS to identify the dominant acceptance criteria of the original design. The femur axial load acceptance criteria event has the lowest reliability (46%) followed by the HIC event (58%) and the door aperture closure event (73%). One approach to improve the reliability is to change vehicle parameters to improve the reliability for the dominant criteria. However, a parameter change such as vehicle strength/stiffness may have a beneficial effect on certain acceptance criteria but be detrimental to others. A system reliability analysis was used to include the contribution of all acceptance criteria to correctly quantify the vehicle reliability and identify important parameters. A redesign analysis was performed using the computed probabilistic sensitivity factors. These sensitivities were used to identify the most effective changes in model parameters to improve the reliability. A redesign using 11 design modifications was performed that increased the original reliability from 23% to 86%. Several of the design changes include increasing the rail material yield strength and reducing its variation, reducing the variation of the bumper and rail installation tolerances, and increasing the rail weld stiffness and reducing its variation. The results show that major reliability improvements for occupant injury and compartment intrusion can be realized by certain specific modifications to the model input parameters. A traditional (deterministic) method of analysis would not have suggested these modifications.

Measurement of the Isothermal Volume Dilation Accompanying the Unilateral Extension of Rubber

1959 ◽  
Vol 32 (2) ◽  
pp. 428-433
Author(s):  
Fred G. Hewitt ◽  
Robert L. Anthony
Keyword(s):  
Molecular Weight ◽  
Young’S Modulus ◽  
Experimental Results ◽  
Molecular Weights ◽  
Rubber Specimen ◽  
A Value ◽  
Fractional Increase ◽  
Internal Agreement ◽  
Good Agreement

Abstract The fractional increase in volume accompanying the isothermal extension of soft gum rubber was measured for four rubber samples at mean extensions of 14, 33, and 51%. The chain molecular weights Mc of the four samples were 5500, 5100, 4400, and 3000, with an estimated uncertainty of about 10% in each value of Mc. The observed fractional increase in volume ranged from 3.2×10−5 to 142×10−5, the latter value being observed for the sample of lowest chain molecular weight and at the extension of 51%. The experimental results for each sample have been represented by theoretical curves based on Gee's expression for the fractional increase in volume as a function of the sample extension. The theoretical curves exhibit good agreement with those of Gee, Stern, and Treloar. The process of fitting the theoretical curves to the experimental points constituted a determination of Young's modulus E for each rubber specimen. As a check on the experimental results, and also on the theory employed, determinations of E were also made by two additional methods, namely, from rough stess-strain curves, and from the relation E=3γρRT/Mc. With one exception, the internal agreement between the three determinations of E for the four different samples was satisfactory. The exception noted can probably be ascribed to the use of too small a value of Mc for the sample of lowest chain molecular weight.

scholarly journals Technical note: Monte Carlo genetic algorithm (MCGA) for model analysis of multiphase chemical kinetics to determine transport and reaction rate coefficients using multiple experimental data sets

2017 ◽  
Vol 17 (12) ◽  
pp. 8021-8029 ◽  
Author(s):  
Thomas Berkemeier ◽  
Markus Ammann ◽  
Ulrich K. Krieger ◽  
Thomas Peter ◽  
Peter Spichtinger ◽  
...  
Keyword(s):  
Experimental Data ◽  
Genetic Algorithm ◽  
Monte Carlo ◽  
Kinetic Models ◽  
Reaction Rate ◽  
Rate Coefficients ◽  
Model Parameters ◽  
Data Sets ◽  
Model Input ◽  
Input Parameters

Abstract. We present a Monte Carlo genetic algorithm (MCGA) for efficient, automated, and unbiased global optimization of model input parameters by simultaneous fitting to multiple experimental data sets. The algorithm was developed to address the inverse modelling problems associated with fitting large sets of model input parameters encountered in state-of-the-art kinetic models for heterogeneous and multiphase atmospheric chemistry. The MCGA approach utilizes a sequence of optimization methods to find and characterize the solution of an optimization problem. It addresses an issue inherent to complex models whose extensive input parameter sets may not be uniquely determined from limited input data. Such ambiguity in the derived parameter values can be reliably detected using this new set of tools, allowing users to design experiments that should be particularly useful for constraining model parameters. We show that the MCGA has been used successfully to constrain parameters such as chemical reaction rate coefficients, diffusion coefficients, and Henry's law solubility coefficients in kinetic models of gas uptake and chemical transformation of aerosol particles as well as multiphase chemistry at the atmosphere–biosphere interface. While this study focuses on the processes outlined above, the MCGA approach should be portable to any numerical process model with similar computational expense and extent of the fitting parameter space.

VLE Determination of Carbon Dioxide Loaded Aqueous Alkanolamine Mixtures Using Modified Kent Eisenberg Model

2017 ◽  
Vol 231 (11-12) ◽  
Author(s):  
Humbul Suleman ◽  
Abdulhalim Shah Maulud ◽  
Zakaria Man
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Model Parameters ◽  
Thermodynamic Models ◽  
Carbon Dioxide Absorption ◽  
Proposed Model ◽  
Wide Range ◽  
Experimental Values ◽  
Good Agreement

AbstractA computationally simple thermodynamic framework has been presented to correlate the vapour-liquid equilibria of carbon dioxide absorption in five representative types of alkanolamine mixtures. The proposed model is an extension of modified Kent Eisenberg model for the carbon dioxide loaded aqueous alkanolamine mixtures. The model parameters are regressed on a large experimental data pool of carbon dioxide solubility in aqueous alkanolamine mixtures. The model is applicable to a wide range of temperature (298–393 K), pressure (0.1–6000 kPa) and alkanolamine concentration (0.3–5 M). The correlated results are compared to the experimental values and found to be in good agreement with the average deviations ranging between 6% and 20%. The model results are comparable to other thermodynamic models.

Determination of Forces in a Magnetic Bearing Actuator: Numerical Computation With Comparison to Experiment

1992 ◽  
Vol 114 (4) ◽  
pp. 796-801 ◽  
Author(s):  
J. D. Knight ◽  
Z. Xia ◽  
E. McCaul ◽  
H. Hacker
Keyword(s):  
Relative Permeability ◽  
Free Space ◽  
Flux Distribution ◽  
Magnetic Bearing ◽  
Two Dimensional ◽  
Metal Parts ◽  
A Value ◽  
Axis Of Symmetry ◽  
Good Agreement

Calculations of the forces exerted on a journal by a magnetic bearing actuator are presented, along with comparisons to experimentally measured forces. The calculations are based on two-dimensional solutions for the flux distribution in the metal parts and free space, using finite but constant permeability in the metals. Above a relative permeability of 104 the effects of changes in permeability are negligible, but below 104 decreases in permeability cause significant decreases in the force. The calculated forces are shown to depend on the metal permeability more strongly when the journal is displaced from its centered position. The predicted forces in the principal attractive direction are in good agreement with experiment when a relatively low value of permeability is chosen. The forces measured normal to the axis of symmetry when the journal is displaced from that axis, however, are significantly higher than predicted by theory, even with a value of relative permeability larger than 5000. These results indicate a need for futher work including nonlinear permeability distributions.

scholarly journals Analysis of Heat Transfer through a Protective Clothing Package

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Paulina Gilewicz ◽  
Damian Obidowski ◽  
Krzysztof Sobczak ◽  
Iwona Frydrych ◽  
Agnieszka Cichocka
Keyword(s):  
Heat Transfer ◽  
Numerical Modeling ◽  
Protective Clothing ◽  
Microscopic Level ◽  
Homogeneous Distribution ◽  
Model Parameters ◽  
High Quality ◽  
Measurement Results ◽  
Good Agreement

Abstract The protective clothing packages, which protect the human body against hot factors in a foundry are in continuous development to increase their resistance and comfort of use. The problem of heat transfer through textiles is the active field of research and reliable numerical modeling of this process can be helpful to design high-quality protective products. Therefore, the numerical model of heat transfer through the package based on the aluminized basalt fabric was developed. The macroscopic geometry of weft and warp threads was reproduced in agreement with samples of plain weave basalt fabric. Mapping the stochastically distributed individual monofilaments in basalt threads, as well as modeling the heat transfer between them, was impossible at the microscopic level. Therefore, the weft and warp threads were modeled as a porous material with a homogeneous distribution of basalt and air in their structure. Data from measurements of the bare and aluminized basalt fabrics by the Alambeta device were used to determine the model parameters. The model was used to simulate the heat transfer through the protective package composed of the aluminized basalt fabric, wool clothing, and cotton underwear. A good agreement of model results was found for measurement results in such a package. The presented procedure allowed for the determination of the main thermal properties of tested basalt fabrics.

scholarly journals Dynamics of the wind of LBV stars

1995 ◽  
Vol 163 ◽  
pp. 333-334
Author(s):  
G. L. Israelian ◽  
A. G. Nikoghossian ◽  
L. V. Tambovtseva
Keyword(s):  
Radiation Pressure ◽  
Initial Velocity ◽  
Terminal Velocity ◽  
Driving Mechanism ◽  
Be Stars ◽  
Maximum Phase ◽  
Luminous Blue Variables ◽  
A Value ◽  
Input Parameters ◽  
Good Agreement

Luminous Blue Variables are among the brightest objects and lie at the Humphreys-Davidson empirical limit of maximum luminosity (Lamers 1986b). A distinct feature of these stars is the higher rate of mass loss and the relatively lower terminal velocity than for other stars of the same spectral type. LBV stars show moderate photometric variations with ΔV ⋍ 1 — 2m. They have higher Ṁ and lower v∞ when they are brighter (i.e., have a low Teff). These stars probable represent a short phase in the evolution along the chain O → Of → LBV → WR. After investigating the dynamics of the wind of P Cygni, Lamers (1986a) concluded that the wind was best explained by radiation pressure arising from a large number of optically thin lines in the Balmer continuum. Recently Chen & Marlborough (1993) applied this driving mechanism to Be stars. Application of this mechanism to P Cygni has been criticized by Pauldrach & Puls (1990) who found that P Cygni's wind is driven by radiation pressure due to both optically thick (60 %) and optically thin lines and that it gives rise to the typical β velocity law. In our calculations we used a method developed by Vilkoviskij and Tambovtseva (1992). We assume that Teff, M*, R*, Ṁ and initial velocity v0 at the stellar surface are given. The input parameters have been taken from Lamers (1986b). All four LBV's (except P Cygni) are considered in their maximum phase, i.e., when their winds are expected to be driven by radiation pressure in optically thin lines. A constant value of vo = 20 km/s has been adopted. Force-multiplier parameters k and δ have been taken from Abbott (1982). If we assume that the acceleration of the wind is due to optically thin lines of metals in the Balmer continuum, than we must have α ≪ 1 (Abbott 1982). We stress that there are no calculations available to determine that quantity in the optically thin limit. We will estimate α later for P Cygni but for other stars we will use a as a free parameter. Note that α depends on the ratio of optically thick to optically thin lines in the wind. Basically k depends on the number of lines that produce radiation pressure and in our case a value of k can be even larger than given by Abbott (1982). The results of our calculations are presented in Table I. We give the values of v∞ calculated for the indicated values of input parameters. The terminal velocities are in good agreement with the observational data (Lamers 1986b).

Using the jominy end-quench test for validation of thermo-metallurgical model parameters

2004 ◽  
Vol 120 ◽  
pp. 571-579
Author(s):  
M. Hunkel ◽  
Th. Lübben ◽  
F. Hoffmann ◽  
P. Mayr
Keyword(s):  
Heat Transfer ◽  
Model Parameters ◽  
Simulation Testing ◽  
Peripheral Surface ◽  
Quench Test ◽  
Good Agreement

One of the most popular tests to determine the hardenability of steels is the Jominy-End-Quench-Test. Moreover this test is useful for simulation testing, too. In this paper the determination of heat transfer fluxes over the quenched surface as well as over the peripheral surface is described. The result is used for simulations of the Jominy-End-Quench-Test for two melts of SAE 52100 (100 Cr 6). One of these was taken from literature, one was used for experiments in IWT. Though transformation behaviors differ in an extreme way, the Jominy-End-Quench-Test can be simulated for both steels with good agreement between simulation and measurement.

scholarly journals Modeling of pure components high pressures densities using CK-SAFT and PC-SAFT equations

2018 ◽  
Vol 83 (3) ◽  
pp. 331-343
Author(s):  
Jovana Ilic-Pajic ◽  
Mirko Stijepovic ◽  
Gorica Ivanis ◽  
Ivona Radovic ◽  
Jasna Stajic-Trosic ◽  
...  
Keyword(s):  
High Pressures ◽  
Equations Of State ◽  
Model Parameters ◽  
Calculated Density ◽  
Average Percentage ◽  
Pure Compounds ◽  
Density Values ◽  
Temperature And Pressure ◽  
Good Agreement

SAFT equations of state have been widely used for the determination of different thermo-physical and phase equilibria properties. In order to use these equations as predictive models it is necessary to calculate the model parameters. In this work CK-SAFT and PC-SAFT equations of state were applied for the correlation of pure compounds densities in the wide ranges of temperature and pressure (288.15?413.15 K and 0.1?60 MPa, respectively). The calculations of densities for n-hexane, n-heptane, n-octane, toluene, dichloromethane and ethanol, under high pressure conditions, were performed with the new sets of parameters determined in this paper by CK-SAFT and PC-SAFT. Very good agreement between experimental and calculated density values was achieved, having absolute average percentage deviations lower than 0.5 %.

scholarly journals OptimalI-VCurve Scan Time of Solar Cells and Modules in Light of Irradiance Level

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Matic Herman ◽  
Marko Jankovec ◽  
Marko Topič
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Cell Model ◽  
Parameter Extraction ◽  
Model Parameters ◽  
Extended Model ◽  
Irradiance Level ◽  
Scan Time

High-efficiency solar cells and modules exhibit strong capacitive character resulting in limited speed of transient responses. A too fastI-Vcurve measurement can thus introduce a significant error due to its internal capacitances. This paper analyses theI-Vcurve error of a measured solar cell or module in light of scan time and irradiance level. It rests on a two-diode solar cell model extended by two bias-dependent capacitances, modelling the junction, and the diffusion capacitance. A method for determination of all extended model parameters from a quasistaticI-Vcurve and open-circuit voltage decay measurement is presented and validated. Applicability of the extended model and the developed parameter extraction method to PV modules is demonstrated and confirmed. SPICE simulations of the extended model are used to obtain theI-Vcurve error versus scan time dependence and theI-Vcurve hysteresis. Determination of the optimal scan time is addressed, and finally the influence of the irradiance level on theI-Vcurve scan time and error is revealed. The method is applied but is not limited to three different wafer-based silicon solar cell types.

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