Semi-Empirical Approach for Fission Fragment Energy Degradation in any Elementary Medium

1971 ◽  
Vol 49 (23) ◽  
pp. 3036-3040 ◽  
Author(s):  
M. Hakim ◽  
N. H. Shafrir
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Physical State ◽  
Empirical Equation ◽  
Electronic Energy ◽  
Fission Fragments ◽  
Fitting Procedure ◽  
Wide Range ◽  
Energy Degradation ◽  
Semi Empirical

A semi-empirical equation for the electronic energy loss of fission fragments has been derived by fitting the theoretical approach of Bohr, specifically developed for heavy stopping materials, to experimental data in gases and solids in a wide range of atomic numbers. The fitting procedure was performed by choosing a different expression for the number of electrons of the medium taking part in the stopping process, which includes empirical parameters obtained by fitting to experiment.The equation enables the energy loss of fission fragments in substances of any Z2, regardless of their physical state, to be predicted to a good degree of accuracy down to energies of approximately 20 MeV.

252Cf Fission Fragment Energy Loss Measurements in Elementary Gases and Solids as Compared with Theory

1971 ◽  
Vol 49 (23) ◽  
pp. 3024-3035 ◽  
Author(s):  
M. Hakim ◽  
N. H. Shafrir
Keyword(s):  
Energy Loss ◽  
Entire Range ◽  
Heavy Ion ◽  
Electronic Energy ◽  
Surface Barrier ◽  
Loss Mechanism ◽  
Fission Fragments ◽  
Wide Range ◽  
Semi Empirical ◽  
Good Agreement

Energy loss of 252Cf fission fragments in 15 gases and solids, representing a wide range of atomic numbers throughout the periodic system, has been measured using a calibrated Si surface barrier heavy ion detector. The data are used for a detailed and systematic comparison with existing theoretical treatments of the electronic energy loss mechanism showing that none of them gives overall good agreement for all stopping substances.The Bohr expression for heavy stopping substances, which shows consistent deviation from experiment for the entire range of stopping media, suggests that based on this approach, a semi-empirical modification can be derived.

Energy Loss for Swift Heavy Ions in Different Elemental Absorbers: A Different Approach for Effective Charge Parameterization

2015 ◽  
Vol 238 ◽  
pp. 196-205
Author(s):  
B. Rani ◽  
Kalpana Sharma ◽  
Neetu ◽  
Anupam ◽  
Shyam Kumar ◽  
...  
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Effective Charge ◽  
Heavy Ions ◽  
Close Agreement ◽  
Input Parameter ◽  
Quantum Mechanical ◽  
Swift Heavy Ions ◽  
Calculated Energy ◽  
Semi Empirical

The energy loss for swift heavy ions, covering Z=3-29(~0.2 - 5.0MeV/n), has been calculated in the elemental absorbers like C, Al and Ti. The present calculations are based on Bohr’s approach applicable in both classical and quantum mechanical regimes. The major input parameter, the effective charge, has been calculated in a different way without any empirical/semi-empirical parameterization. The calculated energy loss values have been compared with the available experimental data which results in a close agreement.

Modified Algebraical Cebeci --- Smith Turbulent Viscosity Model for the Entire Surface of a Blunted Cone

2020 ◽  
pp. 28-41
Author(s):  
V.V. Gorskiy ◽  
A.G. Loktionova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Experimental Studies ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Entire Surface ◽  
Wide Range ◽  
Semi Empirical ◽  
Transfer Properties ◽  
Turbulent Pulsations

In order to compute the intensity of laminar-turbulent heat transfer, algebraic or differential models are commonly used, which are designed to compute the contribution of turbulent pulsations to the transfer properties of the gas. This, in turn, dictates the necessity of validating these semi-empirical models against experimental data obtained under conditions simulating the gas dynamics inherent to the phenomenon as observed in practice. The gas dynamic patterns observed during gradient flow around fragments of aircraft structure (such as a sphere or a cylinder) differs qualitatively from the patterns revealed by the flow around the lateral surfaces of these fragments, which necessitates using various semi-empirical approaches in this case, followed by mandatory validation against the results of respective experimental studies. In recent years, there appeared scientific publications dealing with modifying one of the algebraic models designed to compute the contribution of turbulent pulsations in the boundary layer to the transfer properties of the gas; this was accomplished by making use of experimental data obtained for a hemisphere at extremely high Reynolds numbers. The paper proposes a similar modification of the same turbulence model, based on fitting a wide range of experimental data obtained for lateral surfaces of spherically blunted cones. As a result of the investigations conducted, we stated a method for computing laminar-to-turbulent heat transfer over the entire surface of a blunted cone; the accuracy of the method is acceptable in terms of most practical applications. We show that the computational method presented is characterised by minimum error as compared to the most widely spread methods for solving this problem

scholarly journals Refractometric study on binary, ternary, and quaternary solutions made by water, methanol, ethanol, glycerol, D-glucose monohydrate (DGMH), sucrose, and sodium chloride at T = 293.15 K and atmospheric pressure

2019 ◽  
Vol 62 (4) ◽  
Author(s):  
Fardad Koohyar ◽  
Javad Nasiri ◽  
Farhoush Kiani
Keyword(s):  
Refractive Index ◽  
Sodium Chloride ◽  
Atmospheric Pressure ◽  
Empirical Equation ◽  
Refractive Indices ◽  
Glycerol Water ◽  
Binary Solutions ◽  
Wide Range ◽  
Water Glycerol ◽  
Semi Empirical

The glycerol, D-glucose monohydrate (DGMH), sucrose, and sodium chloride are used in food industries and the measurement of properties for these components and their aqueous solutions can be important. In this research work, the refractive indices for binary solutions of (methanol + glycerol), (ethanol + glycerol), ternary solutions of (water + glycerol + DGMH), (water + glycerol + sucrose), (water + sucrose + DGMH), (water + sucrose + ethanol), (water + ethanol + DGMH), (water + NaCl + DGMH), (water + methanol + NaCl), (water + ethanol + NaCl), (water + NaCl + glycerol), (water + sucrose + NaCl), and quaternary solutions of (water + ethanol + sucrose + DGMH), (water + ethanol + sucrose + glycerol), (water + NaCl + sucrose + glycerol) were measured in wide range of mole fractions at T = 293.15 K and atmospheric pressure. For binary solutions of this study, the changes of refractive index on mixing, ∆nD, were calculated in each mole fraction at T = 293.15 K. Also, the refractive index of binary solutions was fitted by a semi-empirical equation. The constant of this equation, Kr, was represented by Koohyar et al. in 2011. This constant can be used to investigate power of interactions between solute and solvent molecules. For ternary and quaternary solutions of this study, a semi-empirical equation was used to determine refractive indices at given temperature. The comparison between calculated and experimental refractive indices shows that there is a good agreement between them especially in lower molal concentrations.    

A comparison of sensitivities between parallel-EELS and EDXS in biological microanalysis

1989 ◽  
Vol 47 ◽  
pp. 400-401
Author(s):  
R.D. Leapman
Keyword(s):  
Experimental Data ◽  
Electron Microscope ◽  
Energy Loss ◽  
X Ray ◽  
Fitting Procedure ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Photodiode Array ◽  
Electron Energy Loss ◽  
Difference Mode

With recent improvements in electron energy loss spectroscopy (EELS) and energy-dispersive x-ray spectroscopy (EDXS) it is useful to compare detection limits for the two techniques, a question originally addressed by Isaacson and Johnson. We have derived theoretical estimates of relative sensitivities for some elements encountered in biological microanalysis. These results are then compared with experimental data obtained using a Hitachi H700H analytical electron microscope equipped with a Gatan (model 666) parallel EELS and with a Tracor Northern Microtrace EDXS detector. These spectra were collected simultaneously using a Tracor TN5500 computer system to control acquisition and to process the EDXS data. Most of the EELS data were collected in the second difference mode to remove channel-to-channel gain variations in the photodiode array and were further processed on another computer using standard reference spectra and a multiple least squares fitting procedure.

scholarly journals Comparison of predictive methods for flow boiling heat transfer in conventional channels and minichannels – the effect of reduced pressure

2018 ◽  
Vol 240 ◽  
pp. 01028 ◽  
Author(s):  
Dariusz Mikielewicz ◽  
Blanka Jakubowska
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Flow Boiling ◽  
Full Range ◽  
Two Phase ◽  
Reduced Pressure ◽  
Flow Boiling Heat Transfer ◽  
Wide Range ◽  
Semi Empirical ◽  
Selection Of

In the paper are presented the results of follow on studies from [1]–[3] using authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data collected from various researchers to investigate the sensitivity of the in-house developed model. The collected experimental data came from various studies from literature and were conducted for the full range of quality variation and a wide range of mass velocity and saturation temperatures. In the work are presented the results of calculations obtained using the in-house developed semi empirical model on selected experimental flow boiling data of the refrigerants: R134a, R1234yf, R600a, R290, NH3, CO2, R236fa, R245fa, R152a and HFE7000. In the present study the particular attention was focused on the influence of reduced pressure on the predictions of the theoretical model. The results of calculations were to test the sensitivity of the flow boiling model with respect to selection of the appropriate two-phase flow multiplier, which is one of the distinctive elements of the in-house model. The main purpose of this paper however is to show the effect of the reduced pressure on the predictions of heat transfer during flow boiling.

Transmission of Solar Radiation Through a Random Medium of Water and Glass

1986 ◽  
Vol 108 (3) ◽  
pp. 199-205 ◽  
Author(s):  
M. J. Witte ◽  
T. A. Newell
Keyword(s):  
Experimental Data ◽  
Solar Radiation ◽  
Empirical Equation ◽  
Random Medium ◽  
The Other ◽  
Rectangular Lattice ◽  
Two Dimensional ◽  
Radiation Exchange ◽  
Radiation Transmission ◽  
Semi Empirical

Two models are presented for the prediction of solar radiation transmission through a random medium of glass and water. One model is based on two-dimensional radiation exchange through a rectangular lattice of glass and water. This model is also applicable for materials other than glass and water. The other model is a semi-empirical equation which expresses the transmission as an exponential function. Both models predict transmittances within 5–10 percent of experimental data.

An Improved Generalized Model for Predicting Frost Growth on a Cold Flat Plate

2010 ◽  
Author(s):  
Q. C. Guo ◽  
W. Wang ◽  
J. Xiao ◽  
W. P. Lu
Keyword(s):  
Experimental Data ◽  
Flat Plate ◽  
Current Model ◽  
Theoretical Models ◽  
Maximum Error ◽  
Open Loop ◽  
Experimental Conditions ◽  
Wide Range ◽  
Semi Empirical ◽  
Frost Growth

A generalized quasi-steady and one-dimensional model for predicting the frost growth on flat plate was proposed based on the previous theoretical models. To improve the predicting ability of the current model, a modified semi-empirical correlation for calculating initial condition of frost density was presented experimentally. The experiments were conducted in a suction-type open-loop wind tunnel under a series of experimental conditions: air temperature −8°C to 19°C, humidity 42% to 80%, velocity 5m/s and the temperature of cold plate −16°C to −8°C. The numerical results of frost thickness, frost density, frost surface temperature and heat flux rate were compared to the experimental data. The simulation results were found agree with the experimental results in a maximum error of 10%. The presented model was further validated by comparing with the previous published experimental data in a wide range of frosting conditions. It was found that the presented model was a simple but universal one to predict the frost growth on cold flat plate.

Flow regimes and energy loss on chutes with upward inclined steps

2004 ◽  
Vol 31 (5) ◽  
pp. 870-879 ◽  
Author(s):  
Chaiyuth Chinnarasri ◽  
Somchai Wongwises
Keyword(s):  
Experimental Data ◽  
Energy Dissipation ◽  
Kinetic Energy ◽  
Energy Loss ◽  
Dimensional Analysis ◽  
Water Flow ◽  
Empirical Equation ◽  
Loss Ratio ◽  
Empirical Correlations ◽  
Drop Number

This paper presents new experimental data on water flow on stepped chutes with upward inclined steps. The slopes of the chutes are 30°, 45°, and 60° whereas the upward angles of the inclined steps are 10°, 20°, and 30°, respectively. Classifications of flow patterns by empirical correlations are presented. Based on dimensional analysis, the important parameters are analyzed, and the relevant dimensionless parameters are established. The energy loss and outlet velocity are strongly influenced by the Drop number and the slope of the stepped chutes. As the Drop number increases, the energy loss ratio decreases. At identical Drop numbers the energy loss ratio on the more moderate slope is greater than on the steeper. The adverse slope of the inclined steps increases the energy loss ratio and decreases the outlet velocity by less than 10%. To estimate the kinetic energy ratio, an empirical equation is proposed.Key words: stepped chutes, inclined step, energy dissipation, skimming flow, spillways.

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