Values Of Resistance Parameters Research Articles

Reactivity of Resorcinol on Pt(511) Single-Crystal Surface and Its Effect on the Kinetics of Underpotentially Deposited Hydrogen and Hydrogen Evolution Reaction in 0.1 M NaOH Electrolyte.

This article presents cyclic voltammetry, Tafel polarization, and ac. impedance spectroscopy examinations of resorcinol (RC) ion reactivity on Pt(511) single-crystal plane and the effect of surface-electrosorbed RC ions on the kinetics of UPD H (underpotentially deposited hydrogen) and HER (hydrogen evolution reaction) processes in 0.1 M NaOH solution. Obtained data delivered a proof for the RC ion surface adsorption and its later electroreduction over the potential range characteristic for the UPD H. A favourable role of platinum-adsorbed resorcinol anions on the kinetics of the UPD H and HER processes is also discussed. The above was explained via the recorded capacitance and charge-transfer resistance parameters (the presence of resorcinol at 1.5 × 10-3 M in 0.1 M NaOH caused significant reduction in the resistance parameter values by 3.9 and 2.6 times, correspondingly, for the UPD of H at 50 mV and the HER process, examined at -50 mV vs. RHE) along with the charge transients, produced by injecting small amounts of RC-based 0.1 M NaOH solution to initially RC-free base electrolyte on the Pt(511) electrode plane (a large cathodic charge-transient density of -90 µC cm-2 was recorded at the electrode potential of 50 mV).

Weather in the Hungarian Lowland from the Point of View of Humans

Weather at different locations in the Hungarian lowland in different seasons (winter, summer) and times of day (morning, noon) is investigated from the human biometeorological point of view. Human thermal load characteristics of weather are described in terms of clothing resistance and operative temperature. Individual human thermal load–thermal sensation relationships have been estimated to study weather variation in the cities of Sopron (cooler part of Hungary) and Szeged (warmer part of Hungary). In the clothing resistance model, the humans are walking at a speed of 1.1 ms−1 in outdoor conditions without sweating. The main findings are as follows. (1) In the early summer mornings, the weather is sensed as “neutral” or “cool”, in these cases the inter-person variation effect is very small. (2) At noon in summer, heat stresses (clothing resistance parameter values less than −2 clo) are registered. In these cases, high temperature and irradiation, as well as low or moderate wind, characterized the atmospheric environment. Then, the inter-person variation effect is clearly visible. (3) The strength of summer heat excess at noon seems to be larger than the strength of winter heat deficit in the early morning. (4) Clothing resistance differences caused by inter-person variations and by weather variations between the cities of Sopron and Szeged are comparable in the majority of cases. When they are not comparable, the site variation effect is much larger than the inter-person variation effect. The clothing resistance model is constructed for individual use and it can be equally applied on both weather and climate data.

Theoretical method for determination of the impact of parasitic torques from the equivalent scheme of induction machines fed by PWM inverter

This paper presents a theoretical method for determining the impact of parasitic induction torques analyzing the quantities and parameters of equivalent schemes of induction machines fed by PWM inverter. Tested are three-pased and one-phase induction machines of different parameter and power types. For the fundamental values of power supply from PWM invertor and for important parameters of tested induction machines, comparation of results has been made, of simulation of electrical (stator and rotor current) and mechanical sizes (number of rotation and parasitic torque) of equivalent schemes of induction machines with squirrel cage and wound (phase) rotor are adopted. Theoretic model contains a correction factor, defined as relation of supply power and electro-engine force of induction machine when the rotor is stable. Comparing the real values of resistance parameters of induction machines and values obtained, taking into account a correction factor, certain discrepancies could be observed between values calculated by equivalent T and Г scheme for both groups of machines which do not exceed a value of 5%. Obtained formulas calculated according to equivalent Г schemes could be used for determination of short circuited currents. They are also used for analysis of properties of electric motors, usually for determination of currents that electric motors in the case of short circuits inject into electric network, as well as for the calculation of operating, mechanical and electrical characteristics of induction machines. Adapted simulation in the software package Matlab-Simulink in the sub-program psbupwm.mdl, replaced missing laboratory equipment, which has been used to perofm comparing of results of matematical method of such a system.

Поведение и резистентность бычков симментальской породы разных генотипов

Abstract. The new genotypes of animals have been created with the use of the Simmental-seedstock herd improver bulls. Selective breeding to be effective for these animals requires understanding the genetic basis of the main types of behavior. For this purpose, an experiment with the Simmetal herd was performed. The average herd-milk production comprised 7.0 thousand kg milk per cow per year (Kursk Region). The bull calves were kept loose. They were divided into two groups of 6 animals each, representing the breeds formed of 1/4 Simmental × 3/4 Holstein in group 1 and 1/8 Simmental × 3/8 Holstein × 1/2 Montbeliarde in group 2. Age-related differences between the bull calves within the groups were no more than two weeks. It was ascertained that the progeny of the Montbeliarde bull fathers (group 2) tended to be calm, spending more time on social behavior. Thus, frequencies of allogrooming in these bull calves at 10–12 months old and 14–15 months old were 50 % and 33 % more, respectively, than that in their peers of a genotype formed of 1/4 Simmental × 3/4 Holstein. Feeding behavior activity and feed intake in the bull calves aged 10–12 months and 14–15 months from group 2 were 18.4 % and 10.8 % higher, respectively, than that in their peers from group 1. The bull calves from group 1 were more nervous, since head butting, which occurred with a physical contact, among the bull calves at 14–15 months old was observed in 50 % of them. In addition, frequencies of agitated behavior (which can be indicated by scratching) exhibited by the bull calves aged 10–11 months and 14–15 months were higher by 16 % and 34 %, respectively, than that in their peers produced from the Montbeliarde bulls. Intense fear associated with a change in the habitual place of keeping was exhibited by 33 % of bull calves from group 1. The innate resistance parameter values for the bull calves of both genotypes were corresponded to the normal variables. The difference between the 14–15-month-old bull calves in the serum bactericidal activity was in favor of the Montbeliarde bulls, comprising 0.1 μ g/mL. Therefore, using the Montbeliarde bulls, overall, has had a positive effect on behavior including feeding behavior activity and feed intake in the produced progeny. It contributed to increasing the liveweights in the bull calves at 10–12 months old and 14–15 months old by 68.5 kg and 97 kg, respectively, when compared to the bull calves with the high rates of consanguinity in Holsteins.

Determining Series Resistance for Equivalent Circuit Models of a PV Module

Literature describes various methods for determining a series resistance for a photovoltaic device from measured IV curves. We investigate use of these techniques to estimate the series resistance parameter for a single diode equivalent circuit model. With simulated IV curves we demonstrate that the series resistance values obtained by these techniques differ systematically from the known series resistance parameter values used to generate the curves, indicating that these methods are not suitable for determining the series resistance parameter for the single diode model equation. We present an alternative method to determine the series resistance parameter jointly with the other parameters for the single diode model equation, and demonstrate the accuracy and reliability of this technique in the presence of measurement errors.

Convergence of Bigelow and Arrhenius models over a wide range of heating temperatures

The heat resistance of the bacterial spores of Moorella thermoacetica, Clostridium sporogenes, Geobacillus stearothermophilus and Bacillus coagulans was determined over a wide range of temperatures using the capillary method and thermoresistometer Mastia. The results showed that the two experimental methods gave similar heat resistance values excepted for Geobacillus stearothermophilus.The effect of temperature on thermal resistance was evaluated using the Arrhenius and Bigelow models. The fit of the heat sensitivity parameters of the Arrhenius and Bigelow models on the heat resistance parameter values obtained over a wide temperature range was equally good. Despite the apparent mathematical incompatibility of the two equations, it is recognized that they yield the same goodness of fit. This paper finds a mathematical reason for this convergence and explains why inside a temperature range of at least 100 °C, no significant difference in the quality of fit between these two models can be found.

Enhancement of Ethanol Oxidation Reaction on Pt (PtSn)-Activated Nickel Foam Through In situ Formation of Nickel Oxy-Hydroxide Layer

The present paper reports on a significant enhancement of ethanol oxidation reaction (EOR), investigated on Pt and PtSn-modified nickel foam electrodes, realized via in situ formation of surface nickel oxy-hydroxide layer in 0.1 M NaOH solution. In the presence of ethanol in electrolyte, adsorbed C2H5OH molecules (and/or its oxidation intermediates) prevent Pt (PtSn) sites from their extensive dissolution upon prolonged surface electrooxidation of Ni foam electrode. The above was elucidated through cyclic voltammetry examinations and a.c. impedance-derived charge transfer resistance parameter values. Surface topography and the presence of catalytic additives were revealed from the combined scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) analyses.Graphical Enhanced EOR kinetics on electrooxidized Pt/PtSn Ni foam. Surface-adsorbed ethanol/oxidation intermediates prevent Pt/PtSn catalyst sites. Pt/PtSn-modified Ni foam—introductory anode for alkaline direct ethanol fuel cell.

Numerical modelling of gravel unconstrained flow experiments with the DAN3D and RASH3D codes

Landslide continuum dynamic models have improved considerably in the last years, but a consensus on the best method of calibrating the input resistance parameter values for predictive analyses has not yet emerged. In the present paper, numerical simulations of a series of laboratory experiments performed at the Laboratory for Rock Mechanics of the EPF Lausanne were undertaken with the RASH3D and DAN3D numerical codes. They aimed at analysing the possibility to use calibrated ranges of parameters (1) in a code different from that they were obtained from and (2) to simulate potential-events made of a material with the same characteristics as back-analysed past-events, but involving a different volume and propagation path. For this purpose, one of the four benchmark laboratory tests was used as past-event to calibrate the dynamic basal friction angle assuming a Coulomb-type behaviour of the sliding mass, and this back-analysed value was then used to simulate the three other experiments, assumed as potential-events. The computational findings show good correspondence with experimental results in terms of characteristics of the final deposits (i.e., runout, length and width). Further\\more, the obtained best fit values of the dynamic basal friction angle for the two codes turn out to be close to each other and within the range of values measured with pseudo-dynamic tilting tests.

Model-Based Prediction of Expiratory Resistance Index in Patients with Asthma

Develop a sensitive algorithm and index for detection of asthma patients using forced expiratory flow curves. A lumped-parameter model of forced expiration was developed. The model can predict the flow-volume curve during forced expiratory maneuver. The flow-volume curves generated by the model depend on values of resistance parameters (FER). Use of flow-volume curves recorded from normal subjects and from patients with asthma before and after ventolin inhalation as inputs for the inverse model, yielded the resistance parameters for each case. These parameters are based on the entire information presented in the flow-volume curve and on the reduction in flow at all lung volumes. Forced Expiratory Resistance (FER(N)) indices were estimated at different percent of lung volumes using the inverse model. The index was significantly affected by inhalation of ventolin in asthmatic patients and was insensitive to ventolin inhalation in normal patients. In asthmatic patients, the FER index at five lung volumes (out of eight), was two--five times greater than in normal subjects with p < 0.05 (three of them with p < 0.01). The estimated parameters were sensitive indicators of the degree of lung function impairment and were able to accurately distinguish between healthy and asthmatic patients.

Nonlinear Rayleigh–Taylor instability for hydromagnetic Darcian flow: effect of free surface currents

Capillary-gravity waves of permanent form at the interface between two unbounded magnetic fluids in porous media are investigated. The system is influenced by the horizontal direction of the magnetic field to the separation face of two semi-infinite homogeneous and incompressible fluids, so that the fields allow free-surface currents at the interface. The solutions of the linearized equations of motion under nonlinear boundary conditions lead to derivation of a nonlinear equation governing the interfacial displacement. This equation is accomplished by using the cubic nonlinearity. Taylor theory is used to expand the governing nonlinear equation in the light of the multiple scales in both space and time. The perturbation analysis leads to imposition of two levels of solvability conditions, which are used to construct the well-known nonlinear Ginzburg–Landau equation. The stability criteria are discussed theoretically and numerically and stability diagrams are obtained. Regions of stability and instability are identified for the surface current density. It is found that the stabilizing role for the magnetic field is retarded when the flow is in porous media. Moreover, the increase in the values of resistance parameters plays a dual role, in stability behavior and in the increase in surface current density.

Resistance parameters and water quench test as criteria of thermal shock behaviour of alumina based refractories

The materials investigated were five alumina based commercial refractories with different contents of Al2 O3 +TiO2 from 28 to 78%. Thermal (k thermal conductivity, α coefficient of thermal expansion) and mechanical (E Young's modulus of elasticity, ν Poisson's ratio, σf flexural strength, σm mean strength, γ fracture surface energy) properties of the chosen materials were measured. The thermal shock stability of specimens was determined using a water quench test (JUS B. D.8.319). Fracture and damage resistance parameters were calculated using average values of the measured thermal and mechanical properties. Calculated resistance parameter values were compared with the results of water quench testing. Linear regression analysis showed that fracture (R and R′) and damage (R‴) parameters could be correlated with the results of the water quench test, with high values of the correlation coefficient.

Forest floor evaporation in a dense Douglas fir stand

Forest floor evaporation was measured with an accurate weighing lysimeter during 44 days in early spring and summer. The Penman–Monteith approach was used to model the evaporation rates as well as the temperature difference between forest floor surface and air at 1m height. Values of resistance parameters were slightly different when the Penman–Monteith model was optimized for measured evaporation rates or for measured temperature differences. These discrepancies were partly due to field variability in forest floor water contents but also because our approach considered the forest floor to be isothermal. With the appropriate parameter sets, the model was able to predict measured hourly forest floor evaporation rates and surface temperature dynamics satisfactorily.We show that in the forest discussed in this paper the Penman–Monteith ventilation term dominates over the available energy term. As a result the evaporation flux is matched by an almost equal, sensible heat flux but in opposite direction. Forest floor water content dynamics have a strong control over the evaporation flux. Spatial variability in forest floor water contents cause the 44-day average forest floor evaporation to range from 0.19mmd−1 in a dry part of the forest to 0.3mmd−1 in a wet part with 0.23mmd−1 as a site representative value. © 1997 Elsevier Science B.V.