New Method For Calculation Research Articles

Pore geometry of sandstone derived from pulsed field gradient NMR

Several parameters of pore geometry are needed for estimating permeability which is a key parameter for the characterization of reservoir sandstones. Powerful techniques for probing the pore space are the self-diffusion and the relaxation time NMR methods. However, the quality of results depends on the petrophysical model which underlies the interpretation of measurements. We applied the pulsed field gradient nuclear magnetic resonance (PFG-NMR) technique and measured time-dependent self-diffusion coefficients, D(Δ), of water in anhydrite cemented sandstones with low porosity and high tortuosity. The conventional method of fitting data with a function (Padé approximation) of the surface-to-volume ratio and the tortuosity yielded uncertain results. As part of a novel approach, we developed a numerical simulation code based on physical principles and a fractal pore space model. We compared our method with the Padé approximation and tested with data from the literature. For porous media with low tortuosity values and simple geometry such as randomly packed glass beads, both methods are in good agreement and give similar results. In sedimentary rocks, however, the new method of calculation is able to determine more accurate details of the pore geometry. However, its main advantage occurs in porous media with fractal geometry or with constricted pores, where the D(Δ)/ D 0 curves deviate from the characteristic shape that is found for randomly packed glass beads.

A new method of calculation of the pressure in the stationary Navier–Stokes equations

We represent pressure p with the aid of the ( divdiv * ) - 1 —operator and velocity v . Next, we investigate some double approximation of p and prove convergence in the space L 2 ( Ω ) .

A fuzzy evaluating approach for load sharing characteristics of EGT based on manufacturing and assembly error characteristics

This paper presents a new method for calculation and quality evaluation of load sharing characteristics of epicyclic gear trains (EGT) on the basis of the systematic design and evaluation method. Based on the statistical properties of the errors that originated by manufacturing errors and assembly variations of EGT, the load sharing characteristics of an EGT system can be represented by some random-fuzzy vector chains. By applying the probabilistic-fuzzy theory to the analysis of the equivalent error of the equal-load link, the load sharing failure event of an EGT is induced as a bilateral fuzzy event. The new design criterion is presented for this key performance. It is described as “design variable must be equal in fuzzy to the corresponding allowable value of itself”. Three combinational associative functions for a bilateral fuzzy event are presented and discussed in detail. So the fuzzy-reliability design&quality evaluation model is established for load sharing of the EGT. Finally, a simple example is discussed to apply the method. The result shows the method is valid for design and evaluation of load sharing characteristics of EGT.

Flexural behaviour of stainless steel beams

The present investigation studies the effect of the material non-linearity on the deflection calculation of stainless steel beams. A comparative analysis of experimental results and those obtained by means of different analytical methods is presented. This comparative analysis includes experimental results on deflection obtained from several tested stainless steel beams. The methods studied are the simplified method proposed in Eurocode 3, Part 1-4, ENV-1993-1-4: Design of Steel Structures. General Rules–Supplementary Rules for Stainless Steel, and different methods based on a numerical model that takes into account the material non-linearity. Finally, a new method for calculation of deflections considering the material non-linearity is proposed. It is based on an analytical expression of the moment–curvature relationship for stainless steel cross-sections.

Limitations of the Augis and Bennett Method for Kinetic Analysis of the Crystallization of Glasses and Conditions for Correct Use

The equation proposed by Augis and Bennett for determining the kinetic exponent of the Johnson–Mehl–Avrami (JMA) model is thoroughly analyzed; a new expression, calculated accurately with no assumptions introduced, is proposed. This new method of calculation has been extended to the different kinetic models more commonly used in the literature for describing solid-state reactions. However, determining the JMA exponent from the Augis and Bennett method can lead to an incorrect interpretation of the reaction mechanism unless an additional, independent test is used. A testing method for verifying the applicability of the Augis and Bennett method is proposed. The kinetic analysis of the crystallization of Ge0.3Sb1.4S2.7 has been used for checking this method.

Diode laser absorption spectroscopy measurement of linestrengths and pressure broadening coefficients of the methane 2 ν3 band at elevated temperatures

A diode laser sensor based on absorption spectroscopy has been developed for the measurement of spectroscopic parameters in the R (3) and R (4) manifolds of 2 ν 3 band of CH 4. Individual linestrengths of each transition are determined for a range of temperatures. In addition, collision-broadened half-widths for CO 2, N 2, H 2O, CH 4, and CO collision partners are measured as a function of temperature and pressure for these strongly overlapped transitions. From this, temperature dependence of the collision half-width for each collision partner is determined. Using a new method for calculation of collisional broadening at high temperatures for strongly overlapped transitions makes these transitions accessible for spectroscopy.

Multidomain behavior during Thellier paleointensity experiments: a phenomenological model

The most commonly used method for paleointensity determination, the Thellier method, requires the absence of multidomain magnetic behavior. The influence of multidomain remanence on paleointensity determination and its recognition during the experiment are, however, only partially understood. Here, we present a phenomenological model of TRM acquisition and its application to the Thellier experiment. This model is an extension of the approach of [Earth Planet. Sci. Lett. 188 (2001) 45] and is used to investigate, beside other multidomain characteristics, the effect of pTRM*-tails. Furthermore, the appropriateness of typically applied checks during paleointensity determination like alteration checks, pTRM*-tail checks and additivity checks is scrutinized. It is shown that pTRM*-tails significantly affect the shape of the Arai diagram. Concave curvature of the Arai plot for samples containing multidomain particles is related to remanences with unblocking temperatures below their respective blocking temperatures. pTRM*-tails, however, which affect unblocking temperatures above the respective blocking temperatures, lead to a convex shape. An overlap of both convex and concave characteristics can produce s-shaped Arai diagrams [Phys. Earth Planet. Int.]. The effect of pTRM*-tails is strongly dependent on the angle and intensity difference between applied field and NRM of the sample. The commonly used in-field alteration check is biased by pTRM*-tails and shows deviations from the expected value even if alteration is absent. pTRM*-tail checks show the presence of tails and thus give evidence for multidomain behavior, only if the laboratory field is applied in a different direction than the NRM. The larger the angle between NRM and laboratory field, the larger the value of the pTRM*-tail check. A new method for calculation of the pTRM*-tail check is proposed which accounts for such angular difference, as well as intensity differences. Conducting the Thellier experiment with alteration checks, pTRM*-tail checks, and additivity checks at an angle between NRM and laboratory field > 0, provides the possibility to unequivocally identify multidomain bias.

A new method of determining the reversible magnetization loop of bulk high-temperature superconductors

A new method of calculation of the magnetization loop of bulk high-temperature superconductors is proposed which employs the results of measurements of the magnetic levitation force.

Evaluation of a new method for calculation of cumulative doses in the rectum wall using repeat ct scans

The rectum wall is an important organ at risk during irradiation of the prostate, the bladder and other organs in the pelvis. It is therefore of great interest to be able reliably to predict normal tissue complication probabilities (NTCPs) for this organ. Because the rectum wall is a hollow organ capable of large deformations between fractions, dose estimates from a single CT are unreliable, and thereby also NTCP estimates. In this study two methods for calculations of cumulative dose distributions from repetitive CT scans are compared. The first is a method presented in this article that uses tracking of volume elements for a direct summation of the doses delivered in the treatment fractions. The other, presented earlier [1), is based on information from dose-volume histograms. The comparisons were made in terms of equivalent uniform doses (EUDs) and NTCPs. The methods were also compared with mean values of EUD and NTCP values from individual CT scans. The study showed that with the relatively symmetric beam arrangements normally used for treatment of prostate and bladder cancer, it is not necessary to use the more laborious method of element tracking. However, an introduction of artificial lateral rectum movements revealed that element tracking is necessary in less symmetric situations.

RP TLC evaluation of logPfor higher fatty acids, hydroxy acids and their esters

Higher fatty acids, hydroxy fatty acids, and their esters have been separated by reversed-phase thin-layer chromatography with three mobile phases. The partition coefficients ( A log P s, IA log P , C log P , log P Kowin , x log P , and log P Rek ) were calculated for the compounds by use of different theoretical procedures. New methods for calculation of partition coefficients on the basis of experimental R M values have been proposed. These methods lead to different partition coefficients for oleic and elaidic acids, geometric isomers of 9-octadecenoic acids.

Calculation of the Thermodynamic Properties of Diatomic Substances Based on the Ornstein-Zernike Equation

The new method of calculation of intermolecular distribution functions is used to calculate various thermodynamic properties of diatomic substances (oxygen, nitrogen, ethane). Good agreement is demonstrated between the calculation and experimental data.

New method of calculation of the partition coefficients of selected alkoxyphenols investigated by RPTLC

Selected meta -and para -alkoxyphenols have been separated by RPTLC on cellulose impregnated with ethyl oleate, with ethanol-water, 40 + 60 (%, v/v ), as mobile phase. New methods of calculation of partition coefficients on the basis of the topological index ° B and experimental R F values have been proposed. These methods enable differentiation between the values of log P for the meta and para isomers of the alkoxyphenols.

Method of calculating side scatter factor for diagnostic X-rays

When computing the amount of leakage from a diagnostic X-ray room, the amount of scattered radiation released from the irradiated body in the lateral direction must be evaluated correctly. The side-scatter factor varies owing to change in the area and/or shape of the field, but the amount of variation is not always linearly proportional to the area of the field. Because the X-ray spectrum depends on the total filtration of the X-ray tube even if the irradiation geometry, X-ray equipment, and tube potential are the same, the side-scatter factor, too, is subject to change. In this paper, we propose a new method of calculation that uses the differential side-scatter factor computed by means of a Monte Carlo simulation, for obtaining the side-scatter factor of diagnostic X-rays. This method, which can calculate the side-scatter factor under any conditions of irradiation, is useful in evaluating the side-scatter factor of diagnostic X-rays.

Use of RP‐TLC and Structural Descriptors to Predict the log P Values of Higher Fatty Acids, Hydroxy Acids, and Their Esters

Selected higher fatty acids, hydroxy acids, and their esters were chromatographed on RP‐TLC plates using methanol:water as mobile phase. R F values obtained by RP‐TLC and log P values by Rekker were used for the new methods of calculation of partition coefficients for investigated compounds. The partition coefficient values estimated by the Rekker method for higher fatty acids, hydroxy acids, and their esters were also correlated with the numerical values of selected structural descriptors. The most accurate prediction of the partition coefficient values of the acids and esters was achieved by use of biparametric equations relating to the topological index A and electrotopological state E ΣOH. These methods enable differentiation between the values of log P for the geometric isomers of 9‐octadecenoic acids, namely for oleic acid and elaidic acid.

Theoretical consideration of problems relating to high coal rate injection into blast furnaces

Some key problems relating to high rate pulverised coal injection into the blast furnace are discussed, including furnace permeability in the lower furnace and raw materials quality, heat compensation and theoretical flame temperature, oxygen enrichment, material and gas distribution control and so on. A new method of calculation of theoretical flame temperatures is proposed, taking into account coal combustion efficiency in the raceway. Measures that should be taken for increasing coal injection rates are discussed.

Determination of Layer-Charge Characteristics of Smectites

AbstractA new method for calculation of layer charge and charge distribution of smectites is proposed. The method is based on comparisons between X-ray diffraction (XRD) patterns of K-saturated, ethylene glycol-solvated, oriented samples and calculated XRD patterns for three-component, mixed-layer systems. For the calculated patterns it is assumed that the measured patterns can be modeled as random interstratifications of fully expanding 17.1 Å layers, partially expanding 13.5 Å layers and non-expanding 9.98 Å layers. The technique was tested using 29 well characterized smectites. According to their XRD patterns, smectites were classified as group 1 (low-charge smectites) and group 2 (high-charge smectites). The boundary between the two groups is at a layer charge of −0.46 equivalents per half unit-cell. Low-charge smectites are dominated by 17.1 Å layers, whereas high-charge smectites contain only 20% fully expandable layers on average. Smectite properties and industrial applications may be dictated by the proportion of 17.1 Å layers present. Non-expanding layers may control the behavior of smectites during weathering, facilitating the formation of illite layers after subsequent cycles of wetting and drying. The precision of the method is better than 3.5% at a layer charge of −0.50; therefore the method should be useful for basic research and for industrial purposes.

Quantum Hall effect in ap-type heterojunction with a lateral surface superlattice

The quantization of Hall conductance in a p-type heterojunction with lateral surface quantum dot superlattice is investigated. The topological properties of the four-component hole wavefunction are studied both in r- and k-spaces. New method of calculation of the Hall conductance in a 2D hole gas described by the Luttinger Hamiltonian and affected by lateral periodic potential is proposed, based on the investigation of four-component wavefunction singularities in k-space. The deviations from the quantization rules for Hofstadter "butterfly" for electrons are found, and the explanation of this effect is proposed. For the case of strong periodic potential the mixing of magnetic subbands is taken into account, and the exchange of the Chern numbers between magnetic subands is discussed.

232 poster A new method for calculation of cumulative rectal doses using repetitive CT-scans

232 poster A new method for calculation of cumulative rectal doses using repetitive CT-scans

A new method for calculation of crystal susceptibilities for X-ray diffraction at arbitrary wavelength. Erratum

A new method for calculation of crystal susceptibilities for X-ray diffraction at arbitrary wavelength. Erratum

Effective dose transmission of diagnostic X-rays through concrete and lead shields

When computing the amount of leakage from a diagnostic X-ray room, the transmission data of X-ray beams through the shielding material, which are used in the computation, must agree with the conditions of use of the X-ray equipment. Even if the tube potential is the same, the energy spectrum of generated X-rays depends on conditions such as high voltage rectification and total filtration, and transmission through the shielding material, too, is subject to change. In this paper, we propose a new method of calculation, which uses transmission data of mono-energetic photon beams computed by means of a Monte Carlo simulation, for obtaining effective dose transmission data through the shielding material of an X-ray beam with spectral distribution. We also present effective dose transmission data of primary X-ray beams and 90 degrees scattered X-ray beams through concrete and lead shields as determined by this method. This method, which can calculate the transmission data of X-ray beams with any spectral distribution, is useful in evaluating the leakage dose of diagnostic X-ray facilities.