bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Stress Problem in a Fluid‐Filled Porous Circular Cylinder
Authors: Noda N. 
Published: May 2007

AbstractThe present paper deals with the one‐dimensional thermal stress problem in a fluid‐filled porous medium, when the fluid in a porous medium flows in a steady state. If a heat conduction equation taking into consideration the flow of the fluid in the porous medium is used, the governing equations for this thermal stress problem become simultaneous quasilinear differential equations. The closed formed solutions for thermal stresses may be obtained in a hollow circular cylinder of the porous medium. Numerical results for thermal stresses are shown in figures.
The Wigner Poisson Problem in a Crystal: Existence, Uniqueness, Semiclassical Limit in the One‐dimensional Case
Authors: Steinrück H. 
Published: May 2007

AbstractWe analyse a quantum‐mechanical model for the transport of electrons in a semiconductor. The model consists of the Wigner equation posed on the bounded Brillouin zone corresponding to the crystal lattice of the semiconductor, with a selfconsistent potential determined by a discrete Poisson equation. We prove global existence and uniqueness of solutions and consider the semiclassical limit.
An Asymptotically Fitted Finite Element Method for Convection Dominated Convection‐Diffusion‐Reaction Problems
Authors: Lube G. 
Published: May 2007

AbstractThis paper is concerned with the convergence of an asymptotically fitted variant of the finite method of streamline‐diffusion type for singularly perturbed elliptic boundary value problems modelling convection dominated convection‐diffusion problems. Numerical results are presented.
Instability by Extension of an Extensible Elastic Column
Authors: Atanacković T. M. , Djukić D. J. S. , Strauss A. M. 
Published: May 2007

AbstractThe instability of an elastic thin column, loaded by an extensional force is studied as a perturbed bifurcation problem. It is assumed that the column axis is extensible. The critical (buckling) load is determined from the single eigenvalue of the linearized equilibrium equations. The post‐critical shape of the column is determined using an extremum variational principle and Ritz procedure. The error estimate for the approximate solution is also presented.
On a Mathematical Comparison of the S‐ and T‐Criteria in Fracture Mechanics
Authors: Theocaris P. S. , Panagiotopoulos P. D. 
Published: May 2007

AbstractWe show that the S‐criterion of fracture mechanics is incompatible with the discontinuity of the velocity fields in the theory of ideal plasticity in contrast to the T‐criterion which permits a correct study of the fracture problem of an elastic ideally plastic body.
Runaway Phenomena and Fluid Approximation Under High Fields in Semiconductor Kinetic Theory
Authors: Poupaud F. 
Published: May 2007

AbstractThe problem of existence of homogeneous stationary solutions of the semiconductor Boltzmann equation is studied. We give a classification of the results according to the behaviour of the collision frequency for high velocities. We underline the case where a critical value of the electric field appears. When the collision frequency is bounded from below, these results allow to derive a fluid approximation of the kinetic equation. It is obtained as a limit of a perturbation which is convenient for high electric fields.
The Calculation of Wing‐Body Interference in Supersonic Flow by Means of SLLT
Authors: Jadic I. 
Published: May 2007

AbstractThe present paper is devoted to the aerodynamic analysis of wing‐fuselage configurations in supersonic flow by means of the lifting line theory (SLLT). This theory is based on the linearized small perturbations equation and assumes a constant distribution of circulation along the chord.In order to simplify the present approach, the fuselage is assumed circular and infinite, while the wing is mid‐positioned. The comparisons cover the cases of rectangular and triangular planforms. The results presented herein show that the accuracy of the method is consistent with the linearized theory, enabling the estimation of wing‐body interference with a moderate computational effort.
On the Expansion of Plastic Regions in the Annular Parts of a Shrink Fit during Assemblage
Authors: Orçan Y. , Gamer U. 
Published: May 2007

AbstractDuring assemblage of a shrink fit consisting of annular shaft and annular hub, partial or complete plastic deformation of either part can occur. If a perfectly plastic annulus is about to be fully plasticized, the interface pressure and the elastic‐plastic border radius of the other annulus, which may harden isotropically in an arbitrary way, assume stationary values. In addition to that, the case of two simultaneously fully plasticized annuli of perfectly plastic behavior is studied.
Absolute und konvektive Orr‐Sommerfeld‐Stabilitätsanalyse von Nachlaufprofilen eines Kraftfahrzeugs
Authors: Brevdo L. , Bohnsack E. , Oertel H. 
Published: May 2007

AbstractDie experimentell gewonnenen, zeitlich gemittelten, turbulenten Nachlaufprofile hinter einem Kraftfahrzeug sind mit einer Orr‐Sommerfeld‐Analyse auf absolute und konvektive Instabilität hin untersucht worden. Dabei konnte ein absolute instabiler Bereich, der ungefähr deckungsgleich mit dem Bereich der quasistationären Rückströmung ist, identifiziert werden. Dies gibt Anlaß zu der Vermutung, daß eine Beeinflussung des Nachlaufs, z. B. durch Ausblasen, mit dem Ziel einer Verringerung des Widerstandes möglich ist. Die Vermutung wird in einem ersten Prinzipexperiment nachgewiesen.
Variational Formulations for Coupled BE/FE Methods in Elastostatics
Authors: Polizzotto C. , Zito M. 
Published: May 2007

AbstractEin gekoppeltes BEM/FEM‐Problem aus der Elastostatik, ein typisches Substrukturproblem, wird im Rahmen der symmetrisch‐definiten BEM behandelt. Es werden vier verschiedene Variationsformulierungen vorgestellt, in deren jeder die Transmissionsbedingungen gegenüber der Trennfläche zwischen FE‐Unterregion und BE‐Unterregion die Rolle natürlicher Randbedingungen spielen. Zwei der oben erwähnten Formulierungen sind Stationaritätsprinzipien in gemischter Form, die anderen beiden sind Sattelpunkt‐Prinzipien, d. h. Kombinationen des Rand‐min‐max‐Prinzips entweder mit dem Prinzip der minimalen Gesamtpotentialenergie oder mit dem Prinzip der minimalen Gesamtkomplementaritätsenergie. Jedes der oben angeführten gekoppelten Prinzipien kann für das durch unabhängige Modellierung für die Unbekannten auf der Trennfläche charakterisierte Diskretisierungsverfahren angewandt werden.
Calculating Some Details of Turbulent Motion in Plane Channel Flow
Authors: Schindler G. 
Published: May 2007

AbstractDie Berechnung der Wirbelströmung in Grenzschichten kann man nach einem Vorschlag von W. Albring durch simultane Integration der Differentialgleichungen für das zeitgemittelte und das momentane Gleichgewicht stufenweise vornehmen. Die Methode läßt sich bei der turbulenten Reibungsschicht im ebenen Kanal anwenden. Das mittlere Geschwindigkeitsprofil und die Wirbelsysteme mit ihrer spektralen Verteilung werden berechnet. Durch Vergleich von Rechen‐ und Meßergebnissen erhält man in den wesentlichen Punkten eine Bestätigung der so gefundenen Lösung.
Investigation of a Non‐Thermal Equilibrium Flow of an Incompressible Fluid in a Cylindrical Tube Filled with Porous Media
Authors: Kuznetsov A. V. 
Published: May 2007

AbstractIn this paper, the transient response of a finite cylindrical tube filled with porous media to a non‐thermal equilibrium forced convective flow of an incompressible fluid through it is investigated. The analysis of the thermal charging of the packed bed is carried out. A two energy equation model is employed to simulate the temperature difference between the fluid and solid phase. Using the perturbation technique, an analytical solution for the problem is obtained. It is show that the temperature difference between the fluid and solid phases forms waves localized in space and propagating from the fluid inlet boundary in the direction of the flow. The amplitude of the waves decreases while the waves propagate downstream.
Regularisierung des Haftzustandes bei Coulombscher Reibung
Authors: Vielsack P. 
Published: May 2007

AbstractBei Stick‐slip‐Bewegungen infolge Coulombscher Reibung wird die volle Trennung von Gleit‐ und Haftbereichen in der Kontaktfläche berücksichtigt. Die zugehörigen Kontaktkräfte werden deshalb unstetig. Regularisierungsmethoden führen grenzschichtartige Näherungen für die Ruhezustände ein. Drei Näherungen werden mit der exakten Lösung eines mechanischen Systems verglichen.
Regularization Procedures of Singular Free Boundary Problems in Rotational Bingham Flows
Authors: Comparini E. 
Published: May 2007

AbstractThe flow of a Bingham fluid in a concentric cylinder viscometer can be give rise to free boundary problems. In the region between the two rotating cylinders the fluid behaves like a viscous fluid if the shear stress, expressed as a linear function of the shear rate, exceeds a yield value, and like a rigid body otherwise. The surfaces dividing fluid and rigid zones are the free boundaries, where we assume that the shear rate is zero. Starting from a model proposed in a previous work, where just one fluid and one rigid zone were present, here we study the physical problem taking into account the possible formation of further rigid zones inside the fluid. We introduce a kind of “regularization” of the problem, pointing out the existence of a unilateral constraint to which the formation of new rigid zones is related. Each time the constraint comes into play, the problem must be reformulated by letting new free boundaries appear bounding the newly created rigid region. Moreover we analyse the possible collapsing of the rigid zones.
Unsteady Flow of a Viscous Fluid Over a Plane Wall
Authors: Erdoǧan M. E. 
Published: May 2007

AbstractThe unsteady flow of an incompressible viscous fluid over a plane wall in the presence of a body force is considered. Three illustrative examples are given. In the first case, it is assumed that the body force is constant, in the second case the body force depends on time in the form of a positive power of time and in the third case the body force varies sinusoidally in time. In the case of the constant force the displacement and the momentum thickness grow as the square root of time as in the case of the flow due to a flat plate suddenly set in motion. It is shown that there are similarities between the flows considered in this paper and the Stoke's first and second problems.
The Compound Matrix Method for Multi‐Point Boundary‐Value Problems
Authors: Ivansson S. 
Published: May 2007

AbstractThe compound matrix method is generalized to handle multi‐point boundary‐value problems for first‐order ordinary differential‐equation (ODE) systems. A general treatment is given, covering all dimensions of the linear ODE system and different locations of the linear boundary conditions in a unified way. The back‐propagation step is performed in a new and simplified way. It is shown how local particular solutions can be used for reduction to a homogeneous ODE system. As an application case, efficient techniques are developed for wave‐propagation computations for range‐independent multi‐region fluid‐solid media. Thick homogeneous layers can be handled reliably without layer splitting.
The preparation and purification of monoglycerides
Authors: Choudhury R. Basu Roy 
Published: May 2007

AbstractMono‐ and diglycerides were produced by reacting the following oils with glycerol: coconut, peanut, sesame, linseed, and sardine. It was shown that the yield of monoglyceride was not dependent upon the fatty acid composition of the oil but on the solubility of glycerol in oil, which is dependent in part on the temperature. An excess of glycerol above that which is soluble does not change the composition of the reaction product. At 180°C, no more than 45% monoglycerides can be formed by glycerolysis.
A kinetic study of the autoxidation of methyl linoleate and linoleic acid emulsions in the presence of sodium chloride
Authors: Mabrouk Ahmed Fahmy , Dugan L. R. 
Published: May 2007

AbstractAutoxidation of linoleic acid and methyl linoleate emulsions in aqueous buffer solutions was studied by the rate of oxygen uptake. The oxidation rates of methyl linoleate emulsions increased with an inerease in the pH of the buffer solution. With linoleic acid, oxidation rates rose until the increase reached its peak at pH 5.50 and then decreased gradually to a minimum at pH 8.00.Oxidation rates of methyl linolente and linoleic acid emulsious decreased with increased concentration of NaCl in the system. The effect of variation of pH of the emulsion in the range investigated was similar to that in emulsions without NaCl. There was no evidence that NaCl accelerated the oxidation rates in the system.The observed inhibitory effect of NaCl may result from the decreased solubility of oxygen in the emulsion with the increased concentration of NaCl. Consequently the availability of oxygen would be a limiting factor in oxidation rates.The activation energy for the monomolecular and bimolecular reactions of methyl linoleate and linoleic acid autoxidation was found to be independent of the pH value and sodium chloride concentration of the system. The energy of activations for the monomolecular and bimolecular reactions of methyl linoleate and of linoleic acid are 22,000, 18,200, 19,600, and 16,400 cal./mol., respectively.Spectrophotometric studies of the autoxidized emulsions of linoleic acid and its methyl ester indicate that the magnitude of the absorption at 2325 Å is the same at different pH values. On the contrary, the secondary products showing absorption at 2775 Å are to some extent dependent on the pH value of the emulsion.
Extraction of corn oil by three petroleum solvents
Authors: Arnold Lionel K. , Rowe William E. 
Published: May 2007

Summary and conclusionsRate‐extractions of corn germ oil by heptane, isoheptane, and hexane at the same temperature showed the latter two to be better solvents than heptane. Extraction rate increased with the temperature.Countercurrent extraction in a continuous laboratory pilot plant showed hexane at 157°F. apparently equal to iso‐heptane at 192°F. It is suggested that the boiling of the hexane at 157°F. might account for the better extraction.It can be concluded that hexane is at least as good a solvent for the extraction of corn oil from whole germ as is iso‐heptane.
Esters in human hair fat
Authors: Nicolaides N. , Foster Roscoe C. 
Published: May 2007

SummaryA study was made of the hair fat composition of human adults with special reference to its ester content. Waxes, triglycerides, and a mixture of mono‐and di‐glycerides were isolated and charcterized. Indirect evidence is presented that the free acids of hair fat are derived from lipolysis of triglycerides. Some preferential esterification of some kinds of fatty acids as glycerides and others as waxes was observed. No significant differences could be observed in the analysis of the hair fat of adult males compared with that of adult females of the same age group.
Relation of amount and quality of protein in the diet to free gossypol tolerance by the rat
Authors: Cabell C. A. , Earle I. P. 
Published: May 2007

Summary and ConclusionsThe rat‐repletion method for protein assay has been used to estimate effects on tolerance for free gossypol of a) difference in source or kind of protein; b) level of total nitrogen or protein intake; and c) changes in amino acid content or balance in the nitrogen allowance. The data demonstrate that the first two of these factors at least influence the depression in weight repletion of these protein depleted rats which may be brought about by an intake of free gossypol. It has been shown that a daily intake of 9.5 mg. of free gossypol, when total daily protein intake is limited to 160 mg. of nitrogen, is a borderline level which depresses weight gain when the protein is supplied by some meal mixtures but is without effect with some others.It has further been demonstrated that the toxic or weight‐depressing effect of 9.5 mg. of free gossypol which has been obtained with a nitrogen intake of 160 mg. may be nullified by increasing the protein intake 50% or more. Attempts to render ineffective an intake of 9.5 mg. gossypol at the lower nitrogen level by replacing a part of the nitrogen allowance with different amounts of some amino acid or amino acid combinations have not been markedly successful. The data do not identify the factor or factors in these protein supplements which influence gossypol toxicity. They do however point to the importance of considering both the amount and kind of dietary protein in attempts to establish a minimum level of free gossypol which is toxic for farm species, or a maximum level which will be tolerated.
Isomerization during hydrogenation. IV. Methyl eleostearate
Authors: Allen Robert R. , Kiess Arthur A. 
Published: May 2007

SummaryThe hydrogenation of methyl eleostearate with and without solvent has been studied. The data indicate the stepwise addition of two moles of hydrogen to the conjugated triene to produce equimolar amounts of 9‐, 10‐, 11‐, 12‐, and 13‐octadecenoates. Additional evidence for thecis‐9,trans‐11,trans‐13 structure of α‐eleostearic acid was obtained.
The isomerization of fats during hydrogenation and the metabolism of the component fatty acids
Authors: Allen Robert R. , Johnston Patricia V. 
Published: May 2007

SummaryExtensive positional and geometrical isomerization occurs during the catalytic hydrogenation of edible oils and fats. The extent of this isomerization can be controlled by varying the conditions of hydrogenation.Studies on the nutritional and metabolic aspects of the geometric isomers formed during the hydrogenation of edible fats indicate that the animal organism appears to be capable of metabolizingrans isomers. However there is some evidence to indicate that the deposition oftrans fatty acids in animal tissues may worsen a pre‐existing essential fatty acid deficiency.
Calculation of the distribution of the saturated and unsaturated acyl groups in fats, from pancreatic lipase hydrolysis data
Authors: Vander Wal R. J. 
Published: May 2007

SummaryEvidence has been presented that the proportions of the glyceride types and isomeric forms in some fats in which C16−C18 chains are greatly in excess can be determined by calculations based on a) the percentage of saturated acyl groups in the whole fat, b) the percentage of saturated groups in the 2‐monoglycerides which can be derived from the fats by hydrolysis, c) the assumption that all the saturated and unsaturated acyl groups (S and U) present in each of the three positions in the molecules are dispersed therein at random, and d) the assumption that the proportions of S and U in the 1‐positions are identical with those in the 3‐positions. The method may apply to all predominantly C16−C18 fats and to other fats as well.
Preparation of pure fatty acid methyl esters by countercurrent distribution
Authors: Scholfield C. R. , Nowakowska Janina , Dutton H. J. 
Published: May 2007

SummaryAcetonitrile‐pentane‐hexane makes a desirable solvent system for preparation of pure methyl esters because of its immiscibility, selectivity toward unsaturation, low boiling point, stability, and ease of recovery. Since separated esters are removed from the apparatus dissolved in the pentane‐hexane layer, successive batches may be fractionated without removing the acetonitrile layer from the instrument. Applications have been illustrated for the preparation of methyl linolenate from an 85% linolenate concentrate, methyl linoleate from safflower esters, and methyl arachidonate from pig liver lipids.This procedure provides a source of “natural” fatty acids with the double bond configuration unchanged, in contrast to those from the conventional bromination‐debromination process. Automation of the process is completed by use of a recording refractometer which monitors concentration of solutions issuing from the extractor. Resolutions to be anticipated with lesser numbers of extraction tubes than 200 are calculated for an equal mixture of linoleate and linolenate.
Octadecylsulfuric acid. Properties of the acid, amine salts, and salts of amino acids
Authors: Maurer E. W. , Stirton A. J. , Weil J. K. 
Published: May 2007

SummaryOctadecanol, hexadecanol, tetradecanol, and dodecanol were sulfated with chlorosulfonic acid, and the corresponding alkylsulfuric acids were isolated in a pure state as white crystalline solids with definite melting points.Octadecylsulfuric acid resembles sodium octadecyl sulfate in detergent and surface‐active properties and in stability to hydrolysis at equal concentrations of hydrogen ion. It is more soluble in water than sodium octadecyl sulfate and readily soluble in organic solvents. The critical micelle concentration (0.0387 millimoles/I.) is only about one‐third that of the sodium salt.Isolation of octadecylsulfuric acid as a useful chemical intermediate made possible the preparation of a number of salts with amines and amino acids and their rapid screening for useful properties.
Filtration‐extraction of flaxseed as affected by preparation variables
Authors: Knoepfler N. B. , Spadaro J. J. , McCourtney E. J. , Vix H. L. E. 
Published: May 2007

SummaryThe data presented show that the filtration‐extraction process can be applied to the extraction of oil from flaxseed. General conditions for preparing the material and for extraction have been established. Adequate comminution, cooking, and crisping yielded materials having necessary characteristics for the successful application of the filtration‐extraction process. Mass velocities in excess of 2,000 and residual lipides contents below 1% were obtained when these materials were slurried and extracted at slightly elevated temperatures (130°F.).The conditions of rolling had an appreciable effect upon the efficiency of extraction of flaxseed. One pass through five‐high rolls with clearances of 0.002 in., 0.002 in., 0.002 in., and 0.000 in. between respective rolls proved satisfactory. Apparent optimum cooking moisture levels for efficient oil extraction fall between 17 and 24% maximum initial, and 8.0 to 10.5% as discharged from the cooker. Mass velocities were significantly lowered when maximum initial cooking moisture contents were below 14% since at these moisture levels it becomes necessary to reduce the moisture content to below 8%, as discharged from the cooker, to achieve suitable cooking. At these low moisture levels crisping by evaporative cooling is not effective.The versatility of the filtration‐extraction process, which had been previously adapted to the extraction of oil from cottonseed, soybeans, sesame seed, peanuts, and rice bran, has been extended, with some minor but important modifications in the preparation and extraction conditions, to the extraction of oil from flaxseed.
Sulfates of ethoxylated tridecyl alcohol in dishwashing formulations
Authors: Schar W. C. , Paulson M. H. , Baumgartner F. N. , Wickson E. J. 
Published: May 2007

SummaryThe foam stability of several light‐duty liquid dishwashing formulations containing sulfated ethoxylates of tridecyl alcohol, lauryl alcohol, and nonylphenol have been compared. The effects of water hardness, sulfating agent, and ethylene oxide/hydrophobe mole ratio have been examined. In very soft water formulations containing alkanolamide and tridecyl alcohol derivatives were shown to be especially effective. At higher water‐hardnesses, combinations containing sulfated ethoxylates of tridecyl alcohol and nonylphenol performed best. Optimum ethylene oxide content for the sulfated tridecyl alcohol ethoxylates has been shown to be 4 to 5 moles/mole of alcohol regardless of water hardness or detergent concentration. The alcohol ethoxylates were shown to be more tolerant of stronger sulfating agents with respect to product quality than the alkylphenol ethoxylates.