scholarly journals Theoretical Model for Prediction of Turning Resistance of Tracked Vehicle on Soft Terrain

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhao Ding ◽  
Yaoming Li ◽  
Zhong Tang
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Theoretical Model ◽  
Close Agreement ◽  
Tracked Vehicles ◽  
Ground Pressure ◽  
Wide Range ◽  
Turning Resistance ◽  
The Moment ◽  
Turning Maneuver

Skid-steered tracked vehicles are commonly used in soft agricultural terrain due to its low ground pressure between vehicle tracks and the ground. However, the sliding and sinkage of the track during a turning maneuver causes considerable turning resistance, which reduces the vehicle's turning ability. Therefore, we constructed a theoretical model that predicts the turning resistance of tracked vehicles—under steady-state conditions on soft terrain—accounting for track sinkage effects and track slip and skid. The results demonstrate that the moment of turning resistance decreases with increased track slip and skid ratio but increases with track sinkage depth. The model-predicted moments of turning resistance for the outer and inner tracks—at a given track sinkage depth and track slip and skid ratio—are in reasonably close agreement with available experimental data. This theoretical model can be employed as a predictor for testing the turning resistance of tracked vehicles operating on a wide range of soils.

A general theory for skid steering of tracked vehicles on firm ground

2001 ◽  
Vol 215 (3) ◽  
pp. 343-355 ◽  
Author(s):  
J Y Wong ◽  
C F Chiang
Keyword(s):  
General Theory ◽  
Close Agreement ◽  
The Other ◽  
Unified Approach ◽  
Tracked Vehicles ◽  
Strong Resemblance ◽  
Turning Resistance ◽  
Skid Steering ◽  
Turning Radius ◽  
The Moment

A general theory for skid steering of tracked vehicles under steady state conditions on firm ground, taking into account the shear stress-shear displacement relationship on the track-ground interface, is presented. The steering behaviour predicted using the general theory bears a strong resemblance to that observed in the field. The variations of sprocket torques for the outer and inner tracks with turning radius predicted by the general theory are in reasonably close agreement with available experimental data. On the other hand, predictions based on Steeds’ theory developed earlier differ greatly from measured results. Using the general theory, the lateral coefficient of friction used in the conventional method for predicting the moment of turning resistance of the track can be quantitatively determined as a function of turning radius. It is believed that the new theory presented in this paper provides a unified approach to the study of the mechanics of skid steering of tracked vehicles and that it may be extended to the study of transient handling behaviour of tracked vehicles.

Combination of a Nonlinear Static and a Linear Dynamic Model of the NETL HyPer System

2010 ◽  
Author(s):  
Bernardo Restrepo ◽  
Larry E. Banta ◽  
Alex J. Tsai ◽  
David Tucker
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Fuel Cell ◽  
Control Systems ◽  
Real Time ◽  
Gas Turbine ◽  
Transfer Functions ◽  
State Variables ◽  
Linear Dynamic ◽  
Wide Range

A nonlinear steady-state thermodynamic model was coupled with linearized dynamic transfer functions to achieve a dynamic description of the NETL HyPer Fuel Cell Gas Turbine (FC/GT) power plant. Nonlinear dynamic models insure accuracy in modeling steady-state behavior over a wide range of operation, but such models are often complex and difficult to implement in real-time using conventional control systems equipment. Conversely, the linearized models provide the ability to predict transient behavior upon which dynamic control systems can be constructed, but are valid only about a narrow operating point. In systems with one or two state variables, it is relatively straightforward to construct controllers that use gain scheduling schemes. But the HyPer system contains many coupled state variables and high degrees of nonlinearity. A method called Real-Time Piecewise Linear Dynamic Modeling (RPLDM) has been implemented to provide both modeling accuracy and real-time performance for the HyPer system over a multi-dimensional hypersurface. Both the nonlinear and the linear constituent models were constructed based on experimental data collected in tests performed on the HyPer system. The models presently consider only the cathode circuit of the fuel cell and contain a recuperated gas turbine system equipped with an electric generator, a simulated fuel cell cathode and various bypass valves for thermal management and system control. The key variables of air temperature, air pressure and mass flow to the cathode of the fuel cell and the turbomachinery have been predicted to within 2% of measured values. This paper presents the modeling technique and comparisons of the model output with experimental data.

scholarly journals Predictions for the Effects of Freestream Turbulence on Turbine Blade Heat Transfer

2004 ◽  
Author(s):  
R. J. Boyle ◽  
Forrest E. Ames ◽  
P. W. Giel
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Steady State ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Pressure Surface ◽  
Wide Range

An approach to predicting the effects of freestream turbulence on turbine vane and blade heat transfer is described. Four models for predicting the effects of freestream turbulence were incorporated into a Navier-Stokes CFD analysis. Predictions were compared with experimental data in order to identify an appropriate model for use across a wide range of flow conditions. The analyses were compared with data from five vane geometries and from four rotor geometries. Each of these nine geometries had data for different Reynolds numbers. Comparisons were made for twenty four cases. Steady state calculations were done because all experimental data were obtained in steady state tests. High turbulence levels often result in suction surface transition upstream of the throat, while at low to moderate Reynolds numbers the pressure surface remains laminar. A two-dimensional analysis was used because the flow is predominantly two-dimensional in the regions where freestream turbulence significantly augments surface heat transfer. Because the evaluation of models for predicting turbulence effects can be affected by other factors, the paper discusses modeling for transition, relaminarization, and near wall damping. Quantitative comparisons are given between the predictions and data.

scholarly journals A quantitative model for the mechanism of action of the cytochrome c peroxidase of Pseudomonas aeruginosa

1992 ◽  
Vol 283 (3) ◽  
pp. 839-843 ◽  
Author(s):  
N Foote ◽  
R Turner ◽  
T Brittain ◽  
C Greenwood
Keyword(s):  
Experimental Data ◽  
Pseudomonas Aeruginosa ◽  
Cytochrome C ◽  
Close Agreement ◽  
Cytochrome C Peroxidase ◽  
Quantitative Model ◽  
Activation Process ◽  
Stopped Flow ◽  
Wide Range ◽  
Time Courses

Each of the elementary reaction steps in both the activation process and catalytic cycle of the cytochrome c peroxidase of Pseudomonas aeruginosa was characterized using stopped-flow methods. A synthesis of these data led to the establishment of a quantitative model for the action of this enzyme. Comparisons were made between experimental data and calculations over a wide range of enzyme, reductant and H2O2 concentrations. Close agreement was found between empirical and simulated reaction time courses from millisecond to tens of seconds time ranges, giving us confidence in the validity of the quantitative model of this enzyme's actions.

Determining Functional Finger Capabilities of Healthy Adults: Comparing Experimental Data to a Biomechanical Model

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Samuel T. Leitkam ◽  
Tamara Reid Bush ◽  
Laura Bix
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Biomechanical Model ◽  
Experimental Models ◽  
Human Hand ◽  
Functional Abilities ◽  
Data Set ◽  
Functional Measures ◽  
Wide Range ◽  
Capture Techniques

The human hand has a wide range of possible functional abilities that can change with age, disease, and injury, and can vary from individual to individual and subsequently can affect a person's quality of life. The objective of this work was to develop a theoretical model of the space that is reachable by the hand, weighted to represent three types of functionality, and to compare this model to an experimental data set obtained from a healthy hand population. A theoretical model, termed the Weighted Fingertip Space, was developed using 50th percentile published hand data and ranges of finger motion. The functional abilities calculated in the model were the abilities to position the fingertip pad, orient the fingertip pad, and apply directional forces through the fingertip pad at all the reachable points in space with respect to the palm. Following the development of this theoretical model, experimental data sets from nine individuals with healthy hands were obtained through motion capture techniques. The experimental data were then compared to the theoretical model. Comparisons between a 50th percentile theoretical model and a subject with a similar sized hand showed good agreement in weighting parameters and overall size and shape of the model spaces. The experimental data set from the entire sample, which ranged from the 2nd to 95th percentile hand sizes, showed resultant models that, on average, reached smaller volumes of space, but yielded higher values of the functional measures within those volumes. Additionally, in comparison to the theoretical model, the variability of the experimental models showed that small changes in hand dimensions and ranges of motion of the finger joints had a large influence in the functional measures of the model. Combined, these results suggest that the modeling technique can calculate functional ability of the hand, but should be used on an individualized basis for evaluating changes in function (e.g., rehabilitation). Further, scaling to hand size has the potential to yield “average” models for larger population samples.

Pressure Drop of Liquid-Liquid Taylor Flow in Mini-Scale Tubing

2016 ◽  
Author(s):  
W. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Flow Rate ◽  
Small Scale ◽  
Flow Rates ◽  
Constant Flow Rate ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, the pressure drop of liquid-liquid segmented flow in small-scale tubing is investigated with experimental and analytical methods. A theoretical model is developed for describing the total pressure drop as a function of slug length and Capillary number. The experiments are conducted with low Reynolds number flows in horizontal, straight mini-scale tubes. A segmented (Taylor) flow is created using several low viscosity silicone oils (1, 3, 5 cSt) and water with a wide range of flow rates. The experimental setup allows the independent variation of liquid slug lengths. The liquids are injected into the mini-scale tubes at a variable (pulsed) flow rate for one liquid, and a constant flow rate for another liquid. The variation of liquid types and flow rates causes numerous combinations of Prandtl, Reynolds, and Capillary numbers to be tested. The theoretical and experimental data is presented in terms of the dimensionless groups fRe or ΔP* and Le* to predict pressure drop in liquid-liquid Taylor flow. The new experimental data agrees well with the new theoretical model of Taylor flow in miniscale tubes. The results of this paper indicate the pressure drop for Taylor flow is higher than in single-phase flow, likely due to the interfacial effects in liquid slugs.

scholarly journals Random Errors of Tycho Astrometry

1995 ◽  
Vol 166 ◽  
pp. 376-376
Author(s):  
V.V. Makarov ◽  
E. Høg
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Prior Information ◽  
A Priori ◽  
Systematic Errors ◽  
Random Errors ◽  
Likelihood Estimator ◽  
Major Drawback ◽  
Wide Range ◽  
Input Catalogue

The paper focuses on the problem of estimation of Tycho astrometry random errors, caused by photon noise. A theoretical model for the random errors was developed on the basis of the Maximum Likelihood estimator. The model provides a satisfactory agreement with experimental data in the wide range of star magnitudes from 4 to 10 for both vertical and inclined slit transits. It is confirmed theoretically, that for fainter stars, which constitute a half of the Tycho star sample, this model is not valid. Moreover, it is demonstrated that a reliable astrometry could hardly be achieved for these faint stars, were it not for a kind of Bayesian approach which is in fact implemented in the processing. This approach uses implicitly a priori astrometric information on positions of the stars. A major drawback of the method is that it introduces some bias in astrometry estimation, of presently unknown size. Nonetheless, no transfer of systematic errors from the input catalogue is expected, for the used prior information comes from Recognition, hence it is based purely on the satellite's own observations. – The inadequacy of the pure ML theory leads us to correct the model empirically, in order to provide reliable formal errors for the astrometric parameters in the final catalogue, for all Tycho magnitudes. In this way, a rms normalized residual is used for each star individually as a scale factor or correction to the formal covariances. Corrected in this way, formal errors are compared directly with external errors, calculated from absolute differences between the Tycho provisional parallaxes in a 30 months solution and the Hipparcos parallaxes of some 100 000 common stars. Analysis of a standard external error shows that the corrected formal errors are robust, and probably even overestimated.

LIQUIDUS THERMO-BAROMETER FOR THE MODELING OF MAGNETITE — MELT EQUILIBRIUM

2018 ◽  
pp. 71-80
Author(s):  
N. S. Aryaeva ◽  
E. V. Koptev-Dvornikov ◽  
D. A. Bychkov
Keyword(s):  
Experimental Data ◽  
Liquidus Temperature ◽  
Vertical Structure ◽  
Maximum Error ◽  
Silicate Melt ◽  
System Of Equations ◽  
Wide Range ◽  
Basaltic Melts ◽  
Multidimensional Statistics

A system of equations of thermobarometer for magnetite-silicate melt equilibrium was obtained by method of multidimensional statistics of 93 experimental data of a magnetite solubility in basaltic melts. Equations reproduce experimental data in a wide range of basalt compositions, temperatures and pressures with small errors. Verification of thermobarometers showed the maximum error in liquidus temperature reproducing does not exceed ±7 °C. The level of cumulative magnetite appearance in the vertical structure of Tsypringa, Kivakka, Burakovsky intrusions predicted with errors from ±10 to ±50 m.

Industrial Labour Force of Russia in 20-30s of XX Century in Russian Historiography

2020 ◽  
pp. 431-449
Author(s):  
Oleg V. Shekatunov ◽  
Konstantin G. Malykhin
Keyword(s):  
Labour Force ◽  
Historical Period ◽  
Russian Industry ◽  
Wide Range ◽  
Scientific Papers ◽  
Potential Formation ◽  
The Moment ◽  
Force Potential ◽  
Modern Russian

The article is devoted to the specifics of studying the industrial labour force of Russia in the 1920s - 1930s in Russian historiography. The various stages of study from the 1920s through the 1930s and up to the last years are concerned. The relevance of the study is due to several factors. These include contradictions in the assessments of Bolshevik modernization of the 1920s and 1930s; projected labour force shortages in modern Russia; as well as the existing labour force shortage in industry at the moment. This determines the relevance of studying the historical period, which was characterized by the most acute personnel problems in the country. The novelty of the study is due to the fact that in modern Russian historiography there is no holistic, integrated view of the problems of the labour force potential formation of Russian industry in the 1920s and 1930s. It is noted that there is no research aimed at analyzing the historiography of these problems. The main stages of the study of industrial labour force are highlighted. The analysis of scientific works correlated with each stage of the study of the topic is performed. The problems and methodology of each stage are considered. A review of a wide range of scientific papers both articles and thesis is presented.

Spectroscopic Studies of Asparaginyl-tRNA Synthetase from Entamoeba histolytica

2019 ◽  
Vol 26 (6) ◽  
pp. 435-448
Author(s):  
Priyanka Biswas ◽  
Dillip K. Sahu ◽  
Kalyanasis Sahu ◽  
Rajat Banerjee
Keyword(s):  
Circular Dichroism ◽  
Steady State ◽  
Entamoeba Histolytica ◽  
Protein Concentration ◽  
Trna Synthetase ◽  
Solvent Exposure ◽  
Steady State Fluorescence ◽  
State Process ◽  
Wide Range ◽  
Circular Dichroïsm

Background: Aminoacyl-tRNA synthetases play an important role in catalyzing the first step in protein synthesis by attaching the appropriate amino acid to its cognate tRNA which then transported to the growing polypeptide chain. Asparaginyl-tRNA Synthetase (AsnRS) from Brugia malayi, Leishmania major, Thermus thermophilus, Trypanosoma brucei have been shown to play an important role in survival and pathogenesis. Entamoeba histolytica (Ehis) is an anaerobic eukaryotic pathogen that infects the large intestines of humans. It is a major cause of dysentery and has the potential to cause life-threatening abscesses in the liver and other organs making it the second leading cause of parasitic death after malaria. Ehis-AsnRS has not been studied in detail, except the crystal structure determined at 3 Å resolution showing that it is primarily α-helical and dimeric. It is a homodimer, with each 52 kDa monomer consisting of 451 amino acids. It has a relatively short N-terminal as compared to its human and yeast counterparts. Objective: Our study focusses to understand certain structural characteristics of Ehis-AsnRS using biophysical tools to decipher the thermodynamics of unfolding and its binding properties. Methods: Ehis-AsnRS was cloned and expressed in E. coli BL21DE3 cells. Protein purification was performed using Ni-NTA affinity chromatography, following which the protein was used for biophysical studies. Various techniques such as steady-state fluorescence, quenching, circular dichroism, differential scanning fluorimetry, isothermal calorimetry and fluorescence lifetime studies were employed for the conformational characterization of Ehis-AsnRS. Protein concentration for far-UV and near-UV circular dichroism experiments was 8 µM and 20 µM respectively, while 4 µM protein was used for the rest of the experiments. Results: The present study revealed that Ehis-AsnRS undergoes unfolding when subjected to increasing concentration of GdnHCl and the process is reversible. With increasing temperature, it retains its structural compactness up to 45ºC before it unfolds. Steady-state fluorescence, circular dichroism and hydrophobic dye binding experiments cumulatively suggest that Ehis-AsnRS undergoes a two-state transition during unfolding. Shifting of the transition mid-point with increasing protein concentration further illustrate that dissociation and unfolding processes are coupled indicating the absence of any detectable folded monomer. Conclusion: This article indicates that GdnHCl induced denaturation of Ehis-AsnRS is a two – state process and does not involve any intermediate; unfolding occurs directly from native dimer to unfolded monomer. The solvent exposure of the tryptophan residues is biphasic, indicating selective quenching. Ehis-AsnRS also exhibits a structural as well as functional stability over a wide range of pH.

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