Electroreflectance Spectra of AlxGa1−xAs Alloys

1971 ◽  
Vol 49 (10) ◽  
pp. 1335-1339 ◽  
Author(s):  
Orazio Berolo ◽  
John C. Woolley
Keyword(s):  
Room Temperature ◽  
Transition Energy ◽  
Transition Energies ◽  
Bowing Parameter ◽  
Band Transition ◽  
Liquid Epitaxy ◽  
Predicted Values ◽  
Experimental Values

Room temperature electroreflectance measurements have been made on samples of AlxGa1−xAs alloys, grown by liquid epitaxy. The variation of the different band transition energies, E0, E1, E2, etc. has been determined as a function of composition x. For each transition energy, the data have been fitted to the relation E = a + bx + cx2 and hence the bowing parameter c determined. These experimental values of c are compared with the predicted values of Van Vechten.

Electron transport properties of InP

1980 ◽  
Vol 58 (7) ◽  
pp. 923-930 ◽  
Author(s):  
H. J. Lee ◽  
J. Basinski ◽  
L. Y. Juravel ◽  
J. C. Woolley
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Thermoelectric Power ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Scattering Parameters ◽  
Electron Transport Properties ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

Measurements of electrical conductivity σ and Hall coefficient RH have been made as a function of temperature in the range room temperature to 250 °C and as a function of magnetic field up to 3.2 T on single crystal n-type samples of InP with carrier concentrations in the range 3.5 × 1021 to 1.2 × 1024 m−3. Theoretical calculations of σ and RH have been made using the method of Fletcher and Butcher and the resulting values fitted to the experimental data by using various scattering parameters as adjustable. The parameters so obtained have then been used to predict further magnetoresistance values and values of thermoelectric power and Nernst–Ettingshausen coefficient. The predicted values of magnetoresistance and thermoelectric power show good agreement with experimental values but not those of the Nernst–Ettingshausen coefficient, possibly due to experimental problems.

Application of Pregelatinized Meal of Rice and Sorghum in the Preparation of Instant Soups: Centesimal Characterization, Technological, Microbiological and Sensory Quality

2019 ◽  
Vol 15 ◽  
Author(s):  
Gomes Acg ◽  
Lima Mcpm ◽  
Caliari M ◽  
Alves Dg ◽  
Machado Alb ◽  
...  
Keyword(s):  
Fast Food ◽  
Water Solubility ◽  
Potato Starch ◽  
Rice Flour ◽  
Extrusion Process ◽  
Experimental Development ◽  
Sorghum Flour ◽  
Predicted Values ◽  
Experimental Values ◽  
Physical And Chemical

Due to the technological importance that the extrusion process represents in the application of fast food, the objective of this work was to apply pregelatinized rice and sorghum flours in the development of an instant preparation soup and to evaluate its centesimal, technological, and their sensorial analysis. Ten formulations of the instant soup were prepared from the mixtures experimental design. According to the experimental results, it can be stated that the predicted values corroborated with the experimental values, that is, a mixture was obtained for the instant soup with the characteristics of water absorption, water solubility, color, luminosity and viscosity close to the predicted by the models. After the physical and chemical analysis, the microbiological characterization of the best formulation defined by the desirability test was used, which demonstrated that the product is suitable to microbiological standards. The results obtained showed that the 80:10:10 instant soup formulation of pregelatinized rice flour, pregelatinized sorghum flour and potato starch allowed the experimental development of a new product with good nutritional characteristics benefits. It was obtained a food with good technological characteristics solubility and absorption in water, good viscosity, light color and with good sensory acceptance by the tasters.

scholarly journals Computational Intelligence Approach for Estimating Superconducting Transition Temperature of Disordered MgB2Superconductors Using Room Temperature Resistivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Taoreed O. Owolabi ◽  
Kabiru O. Akande ◽  
Sunday O. Olatunji
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Room Temperature ◽  
Optimization Technique ◽  
Support Vector ◽  
Measuring Instruments ◽  
Room Temperature Resistivity ◽  
Superconducting Transition ◽  
Experimental Values ◽  
Temperature Resistivity

Doping and fabrication conditions bring about disorder in MgB2superconductor and further influence its room temperature resistivity as well as its superconducting transition temperature (TC). Existence of a model that directly estimatesTCof any doped MgB2superconductor from the room temperature resistivity would have immense significance since room temperature resistivity is easily measured using conventional resistivity measuring instrument and the experimental measurement ofTCwastes valuable resources and is confined to low temperature regime. This work develops a model, superconducting transition temperature estimator (STTE), that directly estimatesTCof disordered MgB2superconductors using room temperature resistivity as input to the model. STTE was developed through training and testing support vector regression (SVR) with ten experimental values of room temperature resistivity and their correspondingTCusing the best performance parameters obtained through test-set cross validation optimization technique. The developed STTE was used to estimateTCof different disordered MgB2superconductors and the obtained results show excellent agreement with the reported experimental data. STTE can therefore be incorporated into resistivity measuring instruments for quick and direct estimation ofTCof disordered MgB2superconductors with high degree of accuracy.

Thermoelectric Power of the Liquid Sn—Te Alloy

1982 ◽  
Vol 37 (10) ◽  
pp. 1127-1131 ◽  
Author(s):  
D. H. Kurlat ◽  
M. Rosen
Keyword(s):  
Thermoelectric Power ◽  
Hard Sphere ◽  
Stoichiometric Composition ◽  
Band Model ◽  
Liquid Alloys ◽  
Sphere Approximation ◽  
The Difference ◽  
Predicted Values ◽  
Experimental Values ◽  
Two Band Model

The Seebeck coefficient (S) of Sni1-x- Tex liquid alloys was measured as a function of concentration and temperature. For 0 ≦ x <0.45 the behaviour is metallic; S values are small and negative, rising linearly with temperature. The predicted values of Ziman's theory when using the hard sphere approximation disagree with the experimental ones. The change in sign occurs for 0.45. For x = 0.5 (stoichiometric composition) the thermoelectric power decreases linearly with temperature. This fact is explained assuming a two-band model. For x ≧ 0.6 the liquid alloy becomes more semiconducting and presents a maximum in the isotherms of S for x = 0.65. For the excess tellurium concentration range we have calculated the difference EF - EV and γ/kB, assuming a S(1/T) law. The experimental values are compared with those of Dancy and Glazov.

Die kinetische Energie ionisierter MolekülfragmenteIII. Quasithermische Ionen von einfachen Paraffinen

1964 ◽  
Vol 19 (7-8) ◽  
pp. 911-925
Author(s):  
Rolf Taubert
Keyword(s):  
Activation Energy ◽  
Statistical Theory ◽  
Mass Spectra ◽  
Transition Energy ◽  
Bond Cleavage ◽  
Theoretical Data ◽  
Initial Energy ◽  
Transition Energies ◽  
Hydrogen Shift ◽  
Reverse Process

From the monotonic increase of the average initial energy of paraffin fragment ions formed by electron impact the existence of unimolecular dissociation sequences is concluded as it is assumed by the statistical theory of mass spectra. For primary decomposition steps the total kinetic energies set free during the respective dissociation processes (transition energies) have been deduced from measured initial energies. The transition energies obtained in this way may be compared with theoretical data for the translational energies in the transition states (statistical energies) as calculated by means of the statistical theory of mass spectra. In case of—C bond cleavage theoretical data are close to the experimental values (≈ 0.1 ev). In case of a C—H bond cleavage, however, theoretical values are always lower than the experimental ones.In rearrangement reactions an activation energy for the reverse process may exist, which should show up, at least partly, in the transition energy. For a primary H2-abstraction process the activation energy for the reverse process aE can be calculated from thermochemical data. The observed transition energies are always lower than the calculated values. A C—C skeleton rearrangement also shows some influence of aΕ on the transition energy. The absolute effect, however, is small—less than 0.1 ev. For hydrogen shift reactions no indication of an aE-contribution was found.

Microstructural Characterization of Chip Segmentation Under Different Machining Environments in Orthogonal Machining of Ti6Al4V

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Shashikant Joshi ◽  
Asim Tewari ◽  
Suhas S. Joshi
Keyword(s):  
Plastic Strain ◽  
Room Temperature ◽  
Microstructural Analysis ◽  
Cutting Speed ◽  
Microstructural Characterization ◽  
Shear Plane ◽  
Band Formation ◽  
Orthogonal Machining ◽  
Two Temperatures ◽  
Experimental Values

Segmented chips are known to form in machining of titanium alloys due to localization of heat in the shear zone, which is a function of machining environment. To investigate the correlation between machining environments and microstructural aspects of chip segmentation, orthogonal turning experiments were performed under three machining environments, viz., room, LN2, and 260 °C. Scanning electron and optical microscopy of chip roots show that the mechanism of chip segment formation changes from plastic strain and mode II fracture at room temperature, to predominant mode I fracture at LN2 and plastic strain leading to shear band formation at 260 °C. The chip segment pitch and shear plane length predicted using Deform™ matched well with the experimental values at room temperature. The microstructural analysis of chips show that higher shear localization occurs at room temperature than the other two temperatures. The depth of machining affected zone (MAZ) on work surfaces was lower at the two temperatures than that of at the room temperature at a higher cutting speed of 91.8 m/min.

Determination of Recrystallization Kinetics Model of 30Cr2Ni4MoV Steel Based on Dislocation Density

2017 ◽  
Vol 263 ◽  
pp. 59-66
Author(s):  
Peng Zhou ◽  
Qing Xian Ma
Keyword(s):  
Dislocation Density ◽  
Model Comparison ◽  
Kinetics Model ◽  
Structure Evolution ◽  
Metallographic Analysis ◽  
Recrystallization Kinetics ◽  
Proposed Model ◽  
Different Temperatures ◽  
Predicted Values ◽  
Experimental Values

A new model to predict the structure evolution of 30Cr2Ni4MoV steel is proposed based on the dislocation density in this research. Hot compression of 30Cr2Ni4MoV steel is carried out on Gleeble 1500 at different temperatures from 1233 K to 1473 K with a strain rate of 0.01 s-1 and the deformed samples are immediately quenched by water to frozen the austenite structure. The recrystallization kinetics model of 30Cr2Ni4MoV steel is successfully established by inverse analysis of the flow curve based on the relation between flow stress and dislocation density. In order to validate the proposed model, comparison between the predicted values and experimental values obtained by metallographic analysis is implemented. It is shown that the predicted results agree with the experimental results well.

Prediction of the Condensation Coefficient on Horizontal Integral-Fin Tubes

1985 ◽  
Vol 107 (2) ◽  
pp. 369-376 ◽  
Author(s):  
R. L. Webb ◽  
T. M. Rudy ◽  
M. A. Kedzierski
Keyword(s):  
Surface Tension ◽  
Theoretical Model ◽  
Surface Tension Force ◽  
Tension Force ◽  
Condensation Coefficient ◽  
Film Drainage ◽  
Predicted Values ◽  
Experimental Values ◽  
Fin Tubes

A theoretical model is developed for prediction of the condensation coefficient on horizontal integral-fin tubes for both high and low surface tension fluids. The model includes the effects of surface tension on film drainage and on condensate retention between the fins. First, the fraction of the tube circumference that is flooded with condensate is calculated. Typically, the condensation coefficient in the flooded region is negligible compared to that of the unflooded region. Then the condensation coefficient on the unflooded portion is calculated, assuming that surface tension force drains the condensate from the fins. The model is used to predict the R-11 condensation coefficient on horizontal, integral-fin tubes having 748, 1024, and 1378 fpm. The predicted values are within ±20 percent of the experimental values.

Polarization effects in AlxGa1−xN / GaN superlattices

2000 ◽  
Vol 639 ◽  
Author(s):  
Erik L. Waldron ◽  
E. Fred Schubert ◽  
John W. Graff ◽  
Andrei Osinsky ◽  
Michael J. Murphy ◽  
...  
Keyword(s):  
Room Temperature ◽  
Stark Effect ◽  
Blue Shift ◽  
Transition Band ◽  
Polarization Effects ◽  
Quantum Confined Stark Effect ◽  
Free Carriers ◽  
Bulk Gan ◽  
Band Transition ◽  
Photoluminescence Studies

ABSTRACTRoom temperature and low temperature photoluminescence studies of AlxGa1−xN/GaN superlattices reveal a red shift of the dominant transition band relative to the bulk GaN bandgap. The shift is attributed to the quantum-confined Stark effect resulting from polarization fields in the superlattices. A theoretical model for the band-to-band transition energies based on perturbation theory and a variational approach is developed. Comparison of the experimental data with this model yields a polarization field of 4.6 × 105 V/cm for room temperature Al0.1Ga0.9N/GaN and 4.5 × 105 V/cm for room temperature Al0.2Ga0.8N/GaN. At low temperatures the model yields 5.3 × 105 V/cm for Al0.1Ga0.9N/GaN and 6.3 × 105 V/cm for Al0.2Ga0.8N/GaN. The emission bands exhibit a blue shift at high excitation densities indicating screening of internal polarization fields by photo-generated free carriers.

scholarly journals Modeling of Degradation of Diazo Dye in Swirl-Flow Photocatalytic Reactor: Response Surface Approach

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1418
Author(s):  
Waleed Jadaa ◽  
Anand Prakash ◽  
Ajay K. Ray
Keyword(s):  
Light Intensity ◽  
Response Surface ◽  
Swirl Flow ◽  
Quadratic Model ◽  
Catalyst Loading ◽  
Random Pattern ◽  
Photocatalytic Reactor ◽  
Degradation Reactions ◽  
Predicted Values ◽  
Experimental Values

Photocatalytic degradation of Direct Blue 15 (DB15), an azo dye, was studied using a swirl-flow monolithic reactor under UV irradiation. The degradation reactions were carried out to investigate effects of initial dye concentration, catalyst loading, and light intensity at an optimal pH. The experiments were designed and mathematically modelled by CCD-RSM (central composite design-response surface methodology) approach. It was found that the selected parameters significantly affect DB15 degradation. In terms of the linear term, catalyst loading and light intensity had a synergistic effect, while dye concentration registered the opposite effect. Strong interaction was observed between catalyst loading and both light intensity and initial dye concentration compared with the interaction of light intensity and initial dye concentration. Based on the experimental results, a quadratic model was developed to predict the percentage removal of DB15. The predicted values of the model were in good agreement with the experimental values (R2 = 0.987), indicating the model fits well for the parameter space for which experiments were performed. According to diagnostic plots, the model credibility was valid because its residuals were distributed normally and exhibited a random pattern based on their examination versus the predicted values. The results revealed that the initial dye concentration and catalyst concentration have a significant effect on the mineralization time.

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