scholarly journals Modified Arrhenius Equation in Materials Science, Chemistry and Biology

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7162
Author(s):  
Jan Kohout
Keyword(s):  
Experimental Data ◽  
Temperature Difference ◽  
Rate Constants ◽  
Materials Science ◽  
Arrhenius Equation ◽  
Arrhenius Plot ◽  
Maximum Temperature ◽  
Inverse Temperature ◽  
Logarithmic Plot ◽  
Straight Line

The Arrhenius plot (logarithmic plot vs. inverse temperature) is represented by a straight line if the Arrhenius equation holds. A curved Arrhenius plot (mostly concave) is usually described phenomenologically, often using polynomials of T or 1/T. Many modifications of the Arrhenius equation based on different models have also been published, which fit the experimental data better or worse. This paper proposes two solutions for the concave-curved Arrhenius plot. The first is based on consecutive A→B→C reaction with rate constants k1 ≪ k2 at higher temperatures and k1 ≫ k2 (or at least k1 > k2) at lower temperatures. The second is based on the substitution of the temperature T the by temperature difference T − T0 in the Arrhenius equation, where T0 is the maximum temperature at which the Arrheniusprocess under study does not yet occur.

scholarly journals A Study of Developing a Prediction Equation of Electricity Energy Output via Photovoltaic Modules

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1503
Author(s):  
Minsu Kim ◽  
Hongmyeong Kim ◽  
Jae Hak Jung
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Air Temperature ◽  
Temperature Difference ◽  
Prediction Accuracy ◽  
Prediction Equation ◽  
Energy Output ◽  
Photovoltaic Modules ◽  
Mean Error ◽  
Pv Module

Various equations are being developed and applied to predict photovoltaic (PV) module generation. Currently, quite diverse methods for predicting module generation are available, with most equations showing accuracy with ≤5% error. However, the accuracy can be determined only when the module temperature and the value of irradiation that reaches the module surface are precisely known. The prediction accuracy of outdoor generation is actually extremely low, as the method for predicting outdoor module temperature has extremely low accuracy. The change in module temperature cannot be predicted accurately because of the real-time change of irradiation and air temperature outdoors. Calculations using conventional equations from other studies show a mean error of temperature difference of 4.23 °C. In this study, an equation was developed and verified that can predict the precise module temperature up to 1.64 °C, based on the experimental data obtained after installing an actual outdoor module.

Diffusion Coefficients of Interest for the Simulation of Heat Treatment in Rare-Earth Transition Metal Magnets

2012 ◽  
Vol 727-728 ◽  
pp. 163-168 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Activation Energy ◽  
Rare Earth ◽  
Transition Metal ◽  
Impurity Atom ◽  
Diffusion Coefficients ◽  
Arrhenius Equation ◽  
Atom Diffusion ◽  
Essential Input

In the case of the modeling of sintering and heat treatments, the diffusion coefficients are an essential input. However, experimental data in the literature about diffusion coefficients for rare-earth transition metal intermetallics is scarce. In this study, the available data concerning diffusion coefficients relevant for rare-earth transition metal magnets are reviewed and commented. Some empirical rules are discussed, for example the activation energy is affected by the size of the diffusing impurity atom. Diffusion coefficients for Dy, Nd and Fe into Nd2Fe14B are given according an Arrhenius equation D=D0exp (-Q/RT). For Dy diffusion into Nd2Fe14B, Q 315 kJ/mol and D08 . 10-4m2/s.

MODELING THE EFFECT OF HEAT EXCHANGE ON THE EFFICIENCY OF A THERMOELECTRIC COOLER

2020 ◽  
Vol 2 ◽  
pp. 132-135
Author(s):  
O.I. MARKOV
Keyword(s):  
Numerical Calculation ◽  
Heat Exchange ◽  
Solid State ◽  
Numerical Modelling ◽  
Temperature Difference ◽  
Maximum Temperature ◽  
Thermoelectric Cooler ◽  
Maximum Temperature Difference ◽  
Peltier Cooler ◽  
Account Heat

Numerical modelling thermal and thermoelectric processes in a branch of solid–state thermoelectric of Peltier cooler is performed, taking into account heat exchange by convection and radiation. The numerical calculation of the branch was carried out in the mode of the maximum temperature difference.

Mechanodestruction of Isoprene Rubber. Part 1. Process Kinetics

2021 ◽  
Vol 80 (3) ◽  
pp. 118-122
Author(s):  
V.P. Dorozhkin ◽  
◽  
E.G. Mokhnatkina ◽  
D.N. Zemsky ◽  
A.D. Valiev ◽  
...  
Keyword(s):  
Experimental Data ◽  
Molecular Mass ◽  
Rate Constants ◽  
Oxidative Destruction ◽  
Process Kinetics ◽  
Mass Fractions ◽  
Rubber Part ◽  
Kinetics Of ◽  
Selection Of ◽  
Isoprene Rubber

A method is proposed that allows us to obtain the values of the rate constants (CR) of the processes of mechanodestruction (mechanical cracking) of kм, oxidative destruction of kо, and recombination of kр macromolecules, as well as the mass fractions of the corresponding fractions of φм, φо, and φр,r involved in the plasticization process (P) of SKI-3 isoprene rubber. The method is based on the selection of the values of these parameters that correspond to the previously obtained experimental data, using the previously obtained recurrent equations and a specially developed program. The dependences of the CR on the time P at 30oC are obtained, which allows us to describe the kinetics of the processes accompanying P at this temperature, and the changes in molecular mass (MM) in this process. It is shown that constant values of CR are established at large times of P. Refined explanations of the nature of the kinetics of the CR change at P are proposed. The MM value of SKI-3 macromolecules that have not undergone destruction is calculated, depending on the time of plasticization.

scholarly journals A sparse modeling for small data: Case studies in controlled syntheses of 2D materials

2022 ◽  
Author(s):  
Yuri Haraguchi ◽  
Yasuhiko Igarashi ◽  
Hiroaki Imai ◽  
Yuya Oaki
Keyword(s):  
Experimental Data ◽  
Case Studies ◽  
Materials Science ◽  
2D Materials ◽  
Small Data ◽  
Sparse Modeling

Data-scientific approaches have permeated in chemistry and materials science. In general, these approaches are not easily applied to small data, such as experimental data in laboratories. Our group has focused...

scholarly journals Data-Driven Modeling of Mechanical Properties of Cast Iron Using Fuzzy Logic

2020 ◽  
Author(s):  
He Tan ◽  
Vladimir Tarasov ◽  
Vasileios Fourlakidis ◽  
Attila Dioszegi
Keyword(s):  
Experimental Data ◽  
Fuzzy Logic ◽  
Cast Iron ◽  
Materials Science ◽  
Fatigue Behavior ◽  
Relevant Literature ◽  
Data Driven ◽  
Fuzzy Logic Systems ◽  
Data Driven Approach ◽  
Data Driven Modeling

For many industries, an understanding of the fatigue behavior of cast iron is important but this topic is still under extensive research in materials science. This paper offers fuzzy logic as a data-driven approach to address the challenge of predicting casting performance. However, data scarcity is an issue when applying a data-driven approach in this field; the presented study tackled this problem. Four fuzzy logic systems were constructed and compared in the study, two based solely upon experimental data and the others combining the same experimental data with data drawn from relevant literature. The study showed that the latter demonstrated a higher accuracy for the prediction of the ultimate tensile strength for cast iron.

scholarly journals Influence of Parallel Plate Stack Spacing on the Temperature Difference of Thermoacoustic Refrigerator by using Helium as a Working Medium

2019 ◽  
Vol 8 (4) ◽  
pp. 2704-2712
Keyword(s):  
Heat Exchanger ◽  
Temperature Difference ◽  
Parallel Plate ◽  
Sheet Material ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Operating Pressure ◽  
Parallel Plates ◽  
Refrigeration System ◽  
Thermoacoustic Refrigerator

The refrigerants are usually provided in the conventional refrigeration system despite the fact that, they produce CFCs and HCFCs, which are hazardous to the environment. However, these disadvantages can be overcome using air or inert gas in the thermoacoustic refrigeration system. The present research involves the effect of spacing of parallel plate stack on the performance of thermoacoustic refrigerator (TAR) in terms of temperature difference (∆T). The entire resonator system as well as other structural parts of the refrigerator are fabricated by using PVC to reduce conduction heat loss. Three parallel plate stacks have been used to study the performance of TAR considering different porosity ratios by varying the gap between the parallel plates (0.28 mm, 0.33 mm and 0.38 mm). The parallel plate stacks are fabricated by using aluminium and mylar sheet material and the working fluid used for the experimental study is helium. The experiments have been carried out with different drive ratios ranging from 0.6% to 1.6% with operating frequencies of 200 – 600 Hz. Also the mean operating pressure used for the experiment is 2 to 10 bar and cooling load of 2 to 10W are considered. The ∆T between the hot heat exchanger and cold heat exchanger is recorded using RTDs and Bruel and Kjaer data acquisition system. Experimental results shows that the lowest temperature measured at cold heat exchanger is -2.1 oC by maintaining the hot heat exchanger temperature at about 32 oC. The maximum temperature difference of 32.90 oC is achieved.

Simulation and Optimization of Temperature Field of Tank Cover with Super Large Diameter during the Creep Aging Forming Process

2021 ◽  
Vol 315 ◽  
pp. 3-9
Author(s):  
Yuan Gao ◽  
Li Hua Zhan ◽  
Hai Long Liao ◽  
Xue Ying Chen ◽  
Ming Hui Huang
Keyword(s):  
Temperature Field ◽  
Field Distribution ◽  
Temperature Difference ◽  
Single Stage ◽  
Maximum Temperature ◽  
Heating Process ◽  
Temperature Field Distribution ◽  
Two Stage ◽  
Maximum Temperature Difference ◽  
Forming Accuracy

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.

An Electronic Model of a Neural Correlate to Experience Obtained When the Stimulus Object is a Straight Line or a Circle

1967 ◽  
Vol 25 (1) ◽  
pp. 189-202 ◽  
Author(s):  
Kristian Holt-Hansen
Keyword(s):  
Experimental Data ◽  
Brain Function ◽  
Stimulus Object ◽  
The Other ◽  
Neural Correlate ◽  
Close Analogy ◽  
Straight Line ◽  
Electronic Model ◽  
Close Relationship ◽  
The Brain

An attempt was made to present an electronic model of the neural correlate to the experiences of straightness and circularity on the basis of experimental data. Two sets of experiments were described. In one Ss had numerous kinds of experience when the stimulus object was a straight line or a circle. These experiments demonstrated a close relationship between a straight line and a circle in experience. The other set of experiments consisted of adjusting the electric voltages fed into a cathode ray oscilloscope so that the displays on the screen corresponded closely to some of the experiences reported by subjects in the first set of experiments. A plausible working hypothesis was put forward on the basis that the electronic functions underlying the working of a cathode ray oscilloscope suggest a close analogy with the brain function underlying the experiences obtained when the stimulus object is a straight line or a circle.

An Unsteady Analysis on Thermal Stratification in the SCS Piping Branched Off the RCS Piping

2003 ◽  
Author(s):  
Kwang-Chu Kim ◽  
Man-Heung Park ◽  
Hag-Ki Youm ◽  
Sun-Ki Lee ◽  
Tae-Ryong Kim ◽  
...  
Keyword(s):  
Temperature Difference ◽  
Thermal Stratification ◽  
Nuclear Power ◽  
Cooling System ◽  
Numerical Study ◽  
Outer Wall ◽  
Maximum Temperature ◽  
Rear Side ◽  
Maximum Temperature Difference ◽  
Starting Point

A numerical study is performed to estimate on an unsteady thermal stratification phenomenon in the Shutdown Cooling System (SCS) piping branched off the Reactor Coolant System (RCS) piping of Nuclear Power Plant. In the results, turbulent penetration reaches to the 1st isolation valve. At 500sec, the maximum temperature difference between top and bottom inner wall in piping is observed at the starting point of horizontal piping passing elbow. The temperature of coolant in the rear side of the 1st isolation valve disk is very slowly increased and the inflection point in temperature difference curve for time is observed at 2700sec. At the beginning of turbulent penetration from RCS piping, the fast inflow generates the higher temperature for the inner wall than the outer wall in the SCS piping. In the case the hot-leg injection piping and the drain piping are connected to the SCS piping, the effect of thermal stratification in the SCS piping is decreased due to an increase of heat loss compared with no connection case. The hot-leg injection piping affected by turbulent penetration from the SCS piping has a severe temperature difference that exceeds criterion temperature stated in reference. But the drain piping located in the rear compared with the hot-leg injection piping shows a tiny temperature difference. In a viewpoint of designer, for the purpose of decreasing the thermal stratification effect, it is necessary to increase the length of vertical piping in the SCS piping, and to move the position of the hot-leg injection piping backward.

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