bluuebunny/crossref_metadata_2025_split huggingface dataset:
Totale Stabilität in der Plastokinetik
Authors: Vielsack P. 
Published: May 2007

AbstractPermanente Störungen einer Gleichgewichtslage erfordern die Untersuchung der totalen Stabilität. Für ein Einfreiheitsgradsystem mit einer Rückführkraftcharakteristik, die makroskopisch elastisch‐plastisches Stoffverhalten beschreibt, werden die vollständigen Lösungen der nichtlinearen Störungsgleichungen bei harmonischer Erregung'angegeben. Mit Hilfe von Phasenportraits lassen sich totale Stabilität im Kleinen, praktische Stabilität (Einspielen), inkrementeller Kollaps, verzögerter Kollaps und plötzlicher Kollaps diskutieren.
Hydrodynamic Forces on Multiple Circular Cylinders Oscillating in a Viscous Incompressible Fluid
Authors: Lin W. H. 
Published: May 2007

AbstractThis paper presents a theoretical analysis and numerical results of the hydrodynamic force coefficients for groups of parallel, circular, rigid cylinders oscillating transversely and harmonically in an unbounded mass of viscous incompressible fluid at rest at infinity. The oscillatory amplitude of these cylinders is assumed to be small compared with their diameters, and the fluid motion is assumed due entirely to the oscillations of the cylinders. The motion of the perturbed fluid and the hydrodynamic forces on the cylinders are obtained by solving a fourth‐order partial differential equation for a stream function with Neumann conditions on the cylinders and the finiteness condition at infinity. The hydrodynamic forces are found to have a self‐excited part and a mutually excited part, each composes of an inertia force and a viscous dissipative force. Numerical results show that the viscous dissipative force predominates over the inertia force in the low‐frequency regime and that the hydrodynamic force coefficients (which are second‐order tensors) are symmetrical. The symmetrical property of hydrodynamic force coefficients is briefly proved by extending the Lorentz reciprocal theorem for steady flows to oscillatory flows. When the number of cylinders is set to one, the theory and numerical results agree very well with those of Stokes (1851) for a single cylinder.
Multibody Kinematical Equations in Terms of Relative Variables
Authors: Schwertassek R. 
Published: May 2007

AbstractFormalisms for computer aided generation of multibody system equations are considered to start from a most simple set of data describing the system's mechanical properties and to apply to most general classes of systems. The generation of the right side of the dynamical equations and of additional relations describing closed loop control of the system motion has been discussed previously for formalisms yielding a state space representation and using relative variables. A state space representation of the system kinematics is gotten easily in case of tree configured systems only. In case of systems with closed circuits the system kinematics must be represented in the general case by a set of differential algebraic equations. These are developed here from data available in a joint kinematics library.
The Nonmonotone Skin Effects in Plane Elasticity Problems Obeying to Linear Elastic and Subdifferential Material Laws
Authors: Panagiotopoulos P. D. , Koltsakis E. K. 
Published: May 2007

AbstractIn the present paper two‐dimensional nonlinear elasticity problems subjected to nonmonotone skin friction effects are formulated and studied. General material laws derived from convex superpotentials are assumed. The friction forces are derived from nonconvex superpotentials through the generalised gradient of F. H. Clarke. The resulting variational‐hemivariational inequalities are studied and the existence and approximation of their solution is discussed by an appropriate combination of monotonicity with compactness arguments.
Umpolygone größten Flächeninhalts
Authors: Hartwig H. , Klötzler R. 
Published: May 2007

AbstractDas geometrische Optimierungsproblem der Bestimmung des flächengrößten Umpolygons zu einem gegebenen konvexen Polygon Pn mit n Ecken ist weder konvex noch konkav. Die Aufgabe läßt sich jedoch im allgemeinen auf ein diskretes dynamisches Optimierungsproblem mit endlichen Zustandsbereichen zurückführen und im Spezialfall regulärer Pn elementar lösen.
The Mean Power of Forces and Moments in Unsteady Aerodynamics
Authors: Send W. 
Published: May 2007

AbstractThe balance of mechanical energy serves as the starting point for a unified and consistent approach to the two basic and inherent mechanisms in unsteady aerodynamics, propulsion and flutter. Both phenomena are mutually dependent and interchangeable with each other by a mere variation of the reduced frequency as the governing magnitude with respect to unsteady effects.
Numerical Analysis of the Thermocapillary Migration of a Fluid Particle under Zero‐Gravity
Authors: Ehmann M. , Wozniak G. , Siekmann J. 
Published: May 2007

AbstractThe present paper deals with the numerical investigation of the thermocapillary motion of a fluid sphere immersed in an unbounded region of a different liquid under weightlessness. The governing equations are solved by means of a finite difference scheme taking the nonlinear terms into account. The influence of inertia and convection on the flow pattern inside and outside the fluid particle is discussed. It is observed that the dimensionless velocity of a drop with fixed diameter decreases with increasing temperature gradient in the case of high temperature gradients. At smaller temperature gradients the dimensionless velocity can exhibit the opposite behavior. These results are in contrast to the analytical solution of the linearized governing equations, where the dimensionless velocity is a constant.
Elastic Stability of an Externally Pressurized Ring with Two Hinges
Authors: Wang C. Y. 
Published: May 2007

AbstractA thin ring or cylinder with two hinges is buckled by external pressure. The buckling pressure is determined as a function or spacing between the hinges. In certain instances two hinges may be more stable than a single hinge. Optimum spacing is one quarter of the perimeter where the buckling pressure is as high as the ring without hinges.
A New Approximate Method for Numerically Solving of ODE Systems in Chemical Kinetics
Authors: Berndt T. , Picht R. , Scherzer K. 
Published: May 2007

AbstractIn a recent paper we described an algorithm to calculate analytical functions for the time‐dependence of concentrations based on a system of ODEs by Laplace transforms. In this paper, we extend the procedure to the case in which the analytical solutions are finished with an additional change function. The method is suitable for models containing first and second order steps. No differences between stiff and nonstiff ODEs are made. We show the application of our method to the case of propane conversion, a mechanism with 32 steps and 20 species. Comparisons with LARKIN (Deuflhard et al.) are made.
On a Self‐Consistent Method to the Analyses of Elastic and Elasto‐Plastic Materials with Inclusions
Authors: Mojia Huang , Bufler H. 
Published: May 2007

AbstractIn this paper, a self‐consistent method is used to estimate the overall properties of elastic and elasto‐plastic materials containing ellipsoidal elastic inclusions or voids. Two important properties of materials with voids are established. The general constitutive relations are derived in a clear form. For elastic problems, we present the relevant stiffness tensor for materials with spherical, penny‐shaped, and cylindrical voids. Further we work out analytically the constitutive behaviour of elasto‐plastic materials with voids under simple tension, pure shear, plane stress, and plane strain, respectively. These special cases illustrate the simplicity and applicability of the proposed method.
On Mathematical Aspects of Dual Variables in Continuum Mechanics. Part 1: Mathematical Principles
Authors: van der Giessen E. , Kollmann F. G. 
Published: May 2007

AbstractIn this paper consisting of two parts we consider mathematical aspects of dual variables appearing in continuum mechanics. Tensor calculus on manifolds as introduced into continuum mechanics by MARSDEN and HUGHES [1] is used as a point of departure. This mathematical formalism leads to additional structure of continuum mechanical theories. Specifically invariance of certain bilinear forms renders unambiguous transformation rules for tensors between the reference and the current configuration. These transformation rules are determined by push‐forwards and pull‐backs, respectively. — In Part 1 we consider the basic mathematical features of our theory. The key aspect of our approach is that, contrary to the usual considerations in this field, we distinguish carefully between inner products and scalar products. This discrimination is motivated by physical considerations and is subsequently given a firm mathematical basis. Inner products can only be formed with objects living in one and the same vector space. Scalar products, on the other hand, are formed between objects living in different spaces. The distinction between inner and scalar products lead to a distinction between transposes and duals of tensors. Therefore, we distinguish between symmetry and self‐duality. An important result of this approach are new formulae for the computation of push‐forwards and pull‐backs, respectively, of second‐order tensors, which are derived from invariance requirements of inner and scalar products, respectively. In contrast to prior approaches thse new formulae preserve symmetry of symmetric mixed tensors.
To the Analysis of Autoparametric Systems
Authors: Tondl A. 
Published: May 2007

AbstractAutoparametric systems represent a special class of nonlinear systems. Such a system has at least two parts, i.e. two degrees of freedom at least. The first part — the oscillator — vibrates due to external or parametric excitations or due to self‐excitation. A typical feature is represented by the existence of the semi‐trivial solution, which means that only the oscillator vibrates. Under certain conditions the semi‐trivial solution is unstable, and autoparametric resonance is induced. Several examples of these systems together with a survey of the investigation results are presented. Typical properties like saturation effect and the occurrence of non‐periodic vibration are illustrated on examples.
Das Gaußsche Prinzip und das Lagrangesche — Notizen zu einer kaum beachteten Arbeit Paul Stäckels
Authors: Pfister F. 
Published: May 2007

AbstractDie folgenden Ausführungen wurden angeregt durch eine — scheinbar vergessene(!) — Arbeit Paul Stäckels über das Prinzip des kleinsten Zwanges. Es zeigt sich, daß für zahlreiche Fälle, die auch in ihrer praktischen Anwendung von Relevanz sind, das d'Alembert/Lagrangesche Prinzip versagt, während das Gaußsche Prinzip ohne weiteres brauchbar ist. Wie es scheint, wurde diese Erkenntnis in der neueren Forschung bislang nirgendwo rezipiert. Die genannte Arbeit enthält ferner einen Hinweis auf den historischen Ursprung einer für die Mehrkörperdynamik besonders nützlichen Form der Lagrangeschen Gleichungen. Diese ist Gegenstand des Zweiten Teils des Aufsatzes.
Epoxy fatty acid ester plasticizers. Preparation and properties
Authors: Greenspan Frank P. , Gall Ralph J. 
Published: May 2007

SummaryThe preparation of epoxy fatty acid ester plasticizers has been reviewed. These plasticizers can be prepared by epoxidation reactions, utilizing a preformed peracid or anin‐situ technique. A newin‐situ epoxidation process, utilizing hydrogen peroxide and acetic acid in the presence of strong acid catalyst, has been described. Excellent conversions to epoxide have been achieved with a series of monounsaturated and polyunsaturated esters.Epoxy fatty acid esters are excellent plasticizers for vinyl resins. Their performance in a series of additional epoxy plasticizers of vegetable and marine origin is described. Novel epoxy plasticizers based upon mixed acetylated mono‐ and di‐glyceride have been prepared and are found to have excellent plasticizer performance.
The hydrogenation of fatty oils with palladium catalyst. III. Hydrogenation of fatty oils for shortening stock
Authors: Zajcew Mykola 
Published: May 2007

SummaryPalladium‐on‐carbon catalysts are exceedingly active for the hydrogenation of natural unsaturated oils when very mild conditions are used. Selectivity is usually good, andtrans content can be adequately controlled by the proper choice of conditions. In the range of operating variables used in this work,trans formation is lessened with increased agitation and pressure, decreased catalyst activity, decreased concentration of metal in oil and on carrier, and with decreased temperature. Some shortening stocks were obtained which have good physical properties, as expressed by their dilatometric curves.
Some factors in the measurement of the suspending power of aqueous detergent/fabric systems
Authors: Weatherburn A. S. , Bayley C. H. 
Published: May 2007

SummaryThe variability associated with the usual methods for measuring the suspending power of aqueous detergent solutions used to remove soil from textile fibers is pointed out, and a modified method, using multiple washes with very low concentrations of soil, is proposed. Two commonly used artificial soils are compared. Micronex, a typical fine particle carbon black, appears to give data in reasonable accord with practical experience while Aquadag, a suspension of graphite particles, tends to magnify some effects and therefore is more useful for specific tests. Aquadag is found to be highly dispersed in dilute aqueous suspension while Micronex (as well as other carbon blacks) forms relatively large aggregates in water. These aggregates are partially dispersed by vigorous agitation in a Waring Blendor but are more completely dispersed by rotation in the Launder‐Ometer in the presence of fabric, yarn, or fiber of cotton or other textile material. The influence of hard water and of other inorganic salts on suspending power data is discussed. The need for careful selection of type of soil and fabric and for careful interpretation of data is stressed.
Relations between oil, nitrogen, and gossypol in cottonseed kernels
Authors: Stansbury Mack F. , Pons Walter A. , Den Hartog G. T. 
Published: May 2007

SummaryA study was made of the relations between oil, nitrogen, and gossypol contents of cottonseed kernels from the seed of eight commercial varieties of cotton grown at 13 locations during three years. Both variety of seed and environment had a highly significant influence on each constituent whether expressed as percentage of the kernel or as weight of constituent per 100 kernels. Each variety showed a significant positive correlation between oil and gossypol and significant negative correlations between oil and nitrogen and between gossypol and nitrogen, on the basis of percentage‐constituent in the kernel. The amount of both oil and nitrogen elaborated in the kernel tends to be related to the size of the kernel; each of these constituents increases with increased kernel size. The highly significant positive relationship between grams of oil and grams of gossypol per 100 kernels which is evident even when nitrogen is held constant can be explained on the basis that these two constituents are synthesized during the same stage of seed development.Rainfall or temperature had no significant over‐all influence on the nitrogen content of the kernels. Grams of nitrogen per 100 kernels showed a significant negative correlation with mean minimum temperature for 5 of the varieties but was not significantly correlated with total rainfall during the maturation period for any of the varieties. Grams of oil and gossypol per 100 kernels tended to increase with increasing rainfall and decrease with increasing mean temperature.The ratio of nitrogen to gossypol is negatively correlated with the oil content of the kernels. The variation attributed to varietal influence decreases as the oil content of the kernel increases. It is postulated that high ratios are desirable for the production of meals containing a low free‐gossypol content.
Thermal dimerization of fatty ester hypdroperoxides
Authors: Frankel E. N. , Evans C. D. , Cowan J. C. 
Published: May 2007

SummaryWhen autoxidized fatty esters and purified fatty hydroperoxides were decomposed in the absence of oxygen at 210°C., the principal reaction was dimerization of the fatty acid chains with elimination of the hydroperoxide groups. Dimers isolated by molecular distillation (60 to 90% of the polymer) have approximately 1 mole hydroxyl, 0.5 mole carbonyl, and two double bonds per mole of dimer. Diene conjugation in the dimers from polyunsaturated fat hydroperoxides varied from 10 to 23%. The infrared spectra of the dimers were similar to those of the original fatty esters except for one striking band at 2.9 μ, which is attributed to the secondary hydroxyl group. Thecis‐trans diene in the polyunsaturated hydroperoxides was isomerized to thetrans‐trans configuration on dimerization. The methyl oleate hydroperoxide dimer showed only absorption for isolatedtrans double bond. The dimer was not split either by catalytic hydrogenation or by hydrogen iodide, indicating a carbon‐carbon bond between the monomer units. On oxidation with permanganate and periodate, the dimeric acids behaved like a monounsaturated mixture containing double bonds in the C6, C7, C8, C9, and C10 positions in the oleate dimer and in the C8, C9, and C10 positions in the safflower ester dimer. Although the dimers showed no peroxidic oxygen iodometrically with potassium iodide, a reduction occurred with hydriodic acid that may indicate the presence of intramolecular peroxide groups and/or allylic alcohol or carbonyl groups. Bromination with N‐bromosuc‐cinimide and dehydrobromination with N,N‐dimethyl aniline produced no aromatization. Subsequent oxidation of the dehydrobrominated dimer yielded 2.6% residue, which was not aromatic. This evidence indicates that the dimer does not have a six‐membered cyclic structure. Dimerization of the hydroperoxides is suggested as occurring through alkyl or alkoxy hydroperoxide radicals to give carbon‐carbon linked fatty acid dimers and some higher polymeric units.
Quantitative gas chromatography of fatty derivatives. Relative detector responses to C6−C14 saturated methyl esters
Authors: Killheffer J. V. , Jungermann Eric 
Published: May 2007

AbstractThe ralative response of a thermal conductivity cell, in terms of peak area produced per mole of compound, has been determined for the fatty methyl esters caproate through myristate. The values were found to be a linear function of molecular weight.
The biological consequences of feeding polyunsaturated fatty acids to antioxidant‐deficient animals
Authors: Machlin L. J. 
Published: May 2007

AbstractThe addition of polyunsaturated fatty acids (PUFA) to diets deficient in vitamin E and other effective antioxidants results in a variety of symptoms in animals. For example, the feeding of such diets to rats results in muscular dystrophy, testis degeneration, dental depigmentation, brown discoloration of the fat and and uterus and creatinuria Similar diets fed to rabbits and ruminants results in muscular dystrophy. In chickens the symptoms observed are encephalomalacia, lowered egg production, and poor hatchability. The addition of PUFA to diets is known to result in the destruction of vitamin E in the diet or in the tissues of animals as a result of free radicals produced during the autooxidation of the PUFA. However, in several studies, this possible explanation for the development of vitamin E deficiency symptoms has been made untenable. In such studies the more likely explanation for development of symptoms is thein vivo peroxidation of PUFA in the tissues of animals following incorporation of large amounts of PUFA in lipid structures and depletion from the tissues of vitamin E and other biologically effective antioxidants.
Alkyd resins from fumaric and maleic modified pine oleoresin
Authors: Halbrook Noah J. , Wells John A. , Lawrence Ray V. 
Published: May 2007

AbstractFumaric and maleic modified pine oleoresin can be used to prepare oil modified nonphthalic alkyd‐type surface coating vehicles. These vehicles may find use in trim enamels, concrete maintenance paints, and as a fortifier for linseed oil exterior paints. Processing of these resins requires that the temperature be raised to 285°C. for 1 to 1.5 hours and then lowered to 265°C. for a time during the procedure. Fumaric modifications may hold some advantages over maleic modifications. Clear films formed from these resins are characterized by good hardness, flexibility, adhesion, toughness, gloss, and color retention. The shorter oil length resins exhibit these properties to the greatest extent.
Hydrogenation of linolenate. I. Fractionation and characterization studies
Authors: Scholfield C. R. , Jones E. P. , Nowakowska Janina , Selke E. , Sreenivasan B. , Dutton H. J. 
Published: May 2007

AbstractMethyl linolenate hydrogenated at 140°C, with 0.5% Ni catalyst and 1.1 mole of hydrogen at atmospheric pressure was separated into octadecenoate, octadecadienoate, and octadecatrienoate fractions by countercurrent distribution. Gas chromatography on a 200‐ft. capillary Apiezon L column revealed one component in the triene fraction, four in the diene fraction, and nine in the monoene fraction. These components were partially fractionated by low‐temperature crystallization, and their solubilities were correlated with alkali conjugation results, with infrared data forcis andtrans configuration of bonds and with dibasic acids isolated from the fractions after oxidative cleavage. Approximately 45% oftrans acids were present in both the monoene and diene fractions. Considerable migration of double bonds from the original 9, 12, and 15 positions occurred.Cis, cis dienes which could not be conjugated by alkali were formed. Little alteration of the residual methyl linolenate was observed. The results demonstrate the applicability and utility of new techniques of fractionation and analysis to the study of the hydrogenation mechanism.
The oxyethylation of 9, 10‐octadecanediols and 9, 10‐dihydroxystearonitrile. Nonionic soaps
Authors: Wrigley A. N. , Smith F. D. , Stirton A. J. 
Published: May 2007

AbstractThe alkali‐catalyzed reaction of ethylene oxide with themeso‐ anddl‐forms of 9,10‐octadecanediol and withthreo‐9,10‐dihydroxystearonitrile was carried out in an apparatus that was equipped with automatic controls for temperature and pressure.The earlier consumption found for thedl‐form compared to themeso is attributed to intramolecular hydrogen bonding. A characteristic constant for the distribution of products is calculated.The products formed are nonionic surface‐active agents with the hydrophilic portion at the middle rather than at the end of the hydrophobic chain. Properties were primarily determined by the value of n, the average number of oxyethyl groups. Optimum emulsifying properties were found at n=4; optimum wetting at n=12.The oxyethylated nitriles were hydrolyzed to the corresponding “nonionic soaps”, which have typical nonionic characteristics; unlike soap they are not easily precipitated by hard water or various metal ions.