Updating of Probabilistic Corrosion Model Based on Bayesian Procedure

2015 ◽  
Author(s):  
Norio Yamamoto
Keyword(s):  
Bayesian Procedure ◽  
Corrosion Condition ◽  
Frequency Distributions ◽  
Degree Of Belief ◽  
Corrosion Phenomenon ◽  
Corrosion Model ◽  
The Subject ◽  
Thickness Measurements ◽  
Good Agreement ◽  
Corrosion Data

Corrosion condition is predicted based on the corrosion model. The corrosion model is necessary to be identified according to the corrosion data collected from the various vessels because corrosion phenomenon is stochastic. However, in order to predict corrosion condition of one specific vessel, such corrosion model is necessary to be modified to reflect the effect of specific corrosion environment of the subject vessel. In the study, procedure of updating corrosion model was investigated based on Bayesian inference on the parameters in the probabilistic corrosion model which utilizes the thickness measurements data. The developed procedure was demonstrated by the application of actual thickness measurements data of the vessel. Even though the amount of corrosion data was limited, the corrosion prediction model was well updated which could be verified by the concentration of posterior distribution which shows the degree of belief on the parameters in the probabilistic corrosion model. The estimated distributions of coating life and corrosion wastage were compared with the frequency distributions obtained by the corrosion data. The estimated distributions of coating life and corrosion wastage showed good agreement with the frequency distributions obtained by the corrosion data.

Some Limitations in Applying Classical EHD Film Thickness Formulas to a High-Speed Bearing

1981 ◽  
Vol 103 (2) ◽  
pp. 295-301 ◽  
Author(s):  
J. J. Coy ◽  
E. V. Zaretsky
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Heating Effects ◽  
Theoretical Predictions ◽  
Traction Fluid ◽  
Shear Heating ◽  
Thickness Measurements ◽  
Inner Race ◽  
Maximum Stresses ◽  
Good Agreement

Elastohydrodynamic film thickness was measured for a 20-mm ball bearing using the capacitance technique. The bearing was thrust loaded to 90, 448, and 778 N (20, 100, and 175 lb). The corresponding maximum stresses on the inner race were 1.28, 2.09, and 2.45 GPa (185,000, 303,000, and 356,000 psi). Test speeds ranged from 400 to 14,000 rpm. Film thickness measurements were taken with four different lubricants: (a) synthetic paraffinic, (b) synthetic paraffinic with additives, (c) neopentylpolyol (tetra) ester meeting MIL-L-23699A specifications, and (d) synthetic cycloaliphatic hydrocarbon traction fluid. The test bearing was mist lubricated. Test temperatures were 300, 338, and 393 K. The measured results were compared to theoretical predictions using the formulae of Grubin, Archard and Cowking, Dowson and Higginson, and Hamrock and Dowson. There was good agreement with theory at low dimensionless speed, but the film was much smaller than theory predicts at higher speeds. This was due to kinematic starvation and inlet shear heating effects. Comparisons with Chiu’s theory on starvation and Cheng’s theory on inlet shear heating were made.

The State of Polydispersion of Hevea Latex. I

1946 ◽  
Vol 19 (1) ◽  
pp. 176-186
Author(s):  
J. H. E. Hessels
Keyword(s):  
Protein Content ◽  
Hevea Brasiliensis ◽  
The State ◽  
Rubber Content ◽  
Rubber Latex ◽  
Latex Particles ◽  
Rubber Particles ◽  
The Subject ◽  
Points Of View ◽  
Good Agreement

Abstract The rubber particles in the latex of Hevea brasiliensis are present in the form of a polydispersion, and their diameters lie within the range of 0.1 to 3 microns. The rubber hydrocarbon itself is composed of a mixture of macromolecules of different degrees of polymerization. Rubber latex is, therefore, a system which is at the same time both polydispersed and polymolecular. It is well known that the degree of dispersion of a substance governs to a great extent certain properties of the substance. Moreover, astonishing as it may seem, in the great number of investigations which have been made of the composition and properties of latex and crude rubber, almost no attention has been paid to the part which may be played by the dimensions of the latex particles. However, in an investigation concerned with the centrifugation of latex, Loomis and Stump have called attention to this possibility, and in a study of latex obtained by fractionation, and in which the majority of the latex particles were of large dimensions, McGavack came to the conclusion that the protein content is proportional to the surface area of the globules. This limited knowledge of the subject seemed to warrant a more thorough study of the problem, which is of fundamental importance both from the theoretical and practical points of view. The investigation as a whole divided itself into three essential parts: (1) separation of latex into fractions containing particles of different sizes, and measurement of the state of dispersion in these fractions, (2) a study of the relation of these fractions to the composition of the rubber, i.e., the relation between the content of nonrubber components and the size of the latex particles, and (3) a study of the changes in the properties of the rubber hydrocarbon with change in the size of the latex particles. The latex used in this investigation was ordinary latex, containing 38–40 per cent dry-rubber content and preserved with ammonia. For the most important points, a concentrated latex (creamed latex containing 60 per cent dry-rubber content) was also tested. These two latices were about two years old when the investigation was started, and they gave results which were in good agreement with each other. In the present paper, only the data obtained with the first of the two latices are presented.

INHERITANCE OF EARLINESS IN BARLEY

1958 ◽  
Vol 38 (2) ◽  
pp. 219-233 ◽  
Author(s):  
L. P. V. Johnson ◽  
G. I. Paul
Keyword(s):  
Spring Barley ◽  
Genetic Analyses ◽  
Frequency Distributions ◽  
Modifying Genes ◽  
Days To Heading ◽  
Good Agreement

The F1, F2 and F3 of seven crosses between spring barley varieties of differential maturity periods were grown in the same year. Genetic analyses were largely based on F3 breeding types, six of which were distinguishable among frequency distributions of F3 hybrids classified in days-to-heading categories. Each breeding type was determined by characteristic variance and mean days-to-heading values. It was hypothesized that parents in each late × early cross differed by additive, increaser alleles at two loci, giving aiaibibi × a a b b. Theoretically, such a cross produces six F2 breeding types, viz., late, intermediate, and early homozygotes, and late, intermediate, and early heterozygotes; the ratio being 1:2:1:4:4:4. Observed frequencies being in good agreement with these expectations, it was concluded that the hypothesis accounted satisfactorily for the main features of inheritance. Minor discrepancies were attributed to modifying genes, the nature of which could not be determined.

Probablistic analysis of runoff simulations in a small urban catchment

1997 ◽  
Vol 36 (8-9) ◽  
pp. 51-56
Author(s):  
F. Calomino ◽  
P. Veltri ◽  
P. Piro ◽  
J. Niemczynowicz
Keyword(s):  
Frequency Distribution ◽  
Basic Question ◽  
Rainfall Runoff ◽  
Urban Catchment ◽  
Rainfall Events ◽  
Frequency Distributions ◽  
The Common ◽  
Runoff Events ◽  
Peak Discharges ◽  
Good Agreement

In Urban Hydrology, a basic question is whether or not the common methods involving the use of design storms bring to the the some results obtained by those methods that make use of real storms. In general, one can say that different design storms give good results when used with the appropriate model, or, conversely, that good results can be achieved through careful model calibration. On the basis of 51 rainfall-runoff recordings obtained from the experimental catchment of Luzzi (Cosenza, Italy), the frequency distribution of the observed peak discharges was initially computed. Then the runoff events were simulated using Wallrus, a well known simulation model, taking as input the observed precipitations. The frequency distribution of the simulated peak discharges was compared to that of the observed ones, with the aim of calibrating the model on a statistical basis. After that, the rainfall events were analysed, obtaining the frequency distributions of the observed intensities over several durations and developing IDF curves of given frequencies and, then, the Chicago design storms. The plotting positions of the peak discharges simulated by this way show a good agreement with the distribution of both the observed peak discharges and the peak discharges simulated through the real storms.

A Study on the Degradation of Coating and Corrosion of Ship’s Hull Based on the Probabilistic Approach

1998 ◽  
Vol 120 (3) ◽  
pp. 121-128 ◽  
Author(s):  
N. Yamamoto ◽  
K. Ikegami
Keyword(s):  
Probabilistic Models ◽  
Plate Thickness ◽  
Probabilistic Approach ◽  
Actual Data ◽  
General Corrosion ◽  
Corrosion Model ◽  
Sequential Processes ◽  
Paint Coatings ◽  
Thickness Measurements ◽  
Existing Data

In this paper, phenomena of general corrosion are assumed to be the results of three sequential processes: degradation of paint coatings, generation of pitting point, and progress of pitting point. A consistent corrosion model is proposed which can evaluate the generation and progress of corrosion quantitatively by introducing appropriate simple probabilistic models for each process. This probabilistic corrosion model can be identified by analyzing existing data collected from plate thickness measurements. Applicability of this model is verified by comparing the estimated behavior of corrosion progress and dispersion with those from actual data.

Multistage Viscous Micropumps

2004 ◽  
Author(s):  
M. Abdelgawad ◽  
I. Hassan ◽  
N. Esmail ◽  
P. Phutthavong
Keyword(s):  
Flow Rate ◽  
Numerical Data ◽  
Pressure Head ◽  
Future Research ◽  
Shear Stresses ◽  
Vertical Rotor ◽  
Viscous Micropump ◽  
The Subject ◽  
Surrounding Fluid ◽  
Good Agreement

The viscous micropump consists of a cylinder placed eccentrically inside a microchannel, where the rotor axis is perpendicular to the channel axis. When the cylinder rotates, a net force is transferred to the fluid due to the unequal shear stresses on the upper and lower surfaces of the rotor. Consequently, this causes the surrounding fluid in the channel to displace towards the microchannel outlet. The simplicity of the viscous micropump renders it ideal for micro pumping, however, previous studies have shown that its performance is still less than what is required for various applications. The performance of the viscous micropump, in terms of flow rate, pressure head and efficiency, may be enhanced by implementing more than one rotor into the configuration. The present study will numerically investigate the performance of various configurations of the viscous micropumps with multiple rotors, namely the dual-horizontal rotor, the triple-horizontal rotor, the symmetrical-dual-vertical rotor, and the 8-shaped dual-vertical rotor. The development of drag force with time, as well as the viscous resisting torque on the cylinders were studied. In addition, the corresponding drag and moment coefficients were calculated. Results show that the symmetrical-dual-vertical rotor configuration yields the best efficiency, and generates the highest flow rate. The steady state performance of the single-stage micropump was compared with the available experimental and numerical data, and was found to be in very good agreement. This work provides a foundation for future research on the subject of fluid phenomena in viscous micropumps.

Rotational temperature profiles of shock waves in diatomic gases

1971 ◽  
Vol 49 (2) ◽  
pp. 337-351 ◽  
Author(s):  
A. K. Macpherson
Keyword(s):  
Shock Waves ◽  
Rotational Temperature ◽  
Rotational Velocity ◽  
Three Dimensional ◽  
Intermolecular Potential ◽  
Collision Dynamics ◽  
Density Profiles ◽  
Frequency Distributions ◽  
Dimensional Approximation ◽  
Good Agreement

The variation of the translational temperature, rotational temperature, and density through shock waves in oxygen and nitrogen was studied using classical laws of mechanics and a Monte Carlo scheme. The collision dynamics were calculated using an intermolecular potential by Parker with both a two-dimensional approximation and the full three-dimensional calculations. The rotational velocity frequency distributions were also calculated. The average number of collisions a molecule will experience a t various stages passing through a shock wave were found and plotted with the temperature and density profiles. The nitrogen results were compared with experimental results and good agreement was found. This also provided a method for giving a first approximation to the three-dimensional intermolecular potential.

Thermodynamic Interactions in Polymer Systems by Gas—Liquid Chromatography. II. Rubber—Hydrocarbons

1972 ◽  
Vol 45 (6) ◽  
pp. 1665-1668
Author(s):  
Y. B. Tewari ◽  
H. P. Schreiber
Keyword(s):  
Liquid Chromatography ◽  
Thermodynamic Data ◽  
Polymer Concentration ◽  
Gas Liquid Chromatography ◽  
Sorption Data ◽  
Equilibrium Sorption ◽  
Polymeric Systems ◽  
Polymer Systems ◽  
The Subject ◽  
Good Agreement

Abstract The application of gas—liquid chromatography (glc) to the study of thermodynamic interactions in polymeric systems is attractive in its ability to generate data rapidly and to extend these into high polymer concentration ranges which are difficult to study by conventional methods. Several recent publications have shown that glc data can produce thermodynamically meaningful results, our most recent work showing very good agreement in a comparison of thermodynamic interaction parameters calculated from glc and equilibrium sorption data for poly(dimethylsiloxane) (PDMS) interacting with selected hydrocarbons. The demand for accuracy in thermodynamic data is considerable, if, for example, these are to be of use in resolution of varying predictions drawn from theories of solution thermodynamics. It is therefore prudent to extend the test of the rapid method's usefulness by comparing thermodynamic data calculated from conventional equilibrium sorption results and from glc data for additional polymers. The system natural rubber—hydrocarbons lends itself for such a comparison and is the subject matter of this report.

The Role of the Site Sizes in Hydridation of Laves Phases (C14)

2002 ◽  
Vol 2002 (12) ◽  
pp. 620-621
Author(s):  
Mustapha Boulghallat ◽  
Ahmed Jouaiti ◽  
Norbert Gerard
Keyword(s):  
Intermetallic Compound ◽  
Experimental Studies ◽  
New Materials ◽  
Laves Phases ◽  
Basic Criterion ◽  
The Subject ◽  
Good Agreement ◽  
Nickel Cadmium

New materials, especially AB2 substituted compounds are able to form reversible hydrides and are good candidates to substitute the cadmium in rechargeable nickel–cadmium batteries. These systems have been the subject of several theoretical and experimental studies, particularly concerning the reaction between hydrogen and the Laves phases(C14) containing zirconium. We have shown previously that the A2B2 site size is the basic criterion which allows manipulation of the characteristic properties (kinetic and thermodynamic) of intermetallic compound hydrides Zr(MxCr1-x)2 with M=Fe, Ni. In order to generalise the validity of our criterion, we have extended our study to other Laves phases (C14) in the literature. The results are found to be in good agreement.

Prediction of Corrosion Condition Considering Effect of Maintenance

2014 ◽  
Author(s):  
Norio Yamamoto
Keyword(s):  
Prediction Model ◽  
Protective Coatings ◽  
Performance Standard ◽  
Repair Work ◽  
Corrosion Condition ◽  
Paint Coating ◽  
Maintenance And Repair ◽  
Permissible Level ◽  
Corrosion Model ◽  
Full Probability

Corrosion prediction model which takes an effect of maintenance and repair into account is developed based on the full probability corrosion model. Over-all coating repair, touch-up coating repair and renewing repair of worn member are considered. Change in the corrosion condition due to the maintenance and repair work is modeled and possibility of such change is evaluated. Based on the developed model, the effects of these maintenance and repair methods to the corrosion condition are numerically examined and discussed. In these numerical examinations, a conventional paint coating and a coating which meets the PSPC (IMO’s Performance Standard for Protective Coatings) specification are examined. Change in corrosion wastage condition due to the maintenance and repair works is evaluated and compared. And the probability that the corrosion wastage exceeds the permissible level is also evaluated.

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