Showing papers by "Karlsruhe Institute of Technology published in 1974"
TL;DR: In this article, supergauge transformations are defined in four space-time dimensions and their commutators are shown to generate γ5 transformations and conformal transformations, respectively.
2,326 citations
TL;DR: In this article, a Lagrangian model invariant under supergauge transformations is studied and the relations among masses and couplings are shown to be preserved by renormalization.
1,070 citations
TL;DR: In this article, a minimal supergauge invariant extension of quantum electrodynamics is described, which contains a spinor, a scalar and a pseudoscalar field, all charged, plus the photon field and a massless Majorana spinor.
508 citations
353 citations
TL;DR: Superfields are defined as functions of the space-time variable x and of anticommuting two-component spinors θ and θ as mentioned in this paper, and they have definite transformation properties under supergauge transformations.
296 citations
TL;DR: In this article, masgeblichen Haftmechanismen und Agglomerationsverfahren werden einander gegenubergestellt.
Abstract: Die masgeblichen Haftmechanismen und Agglomerationsverfahren werden einander gegenubergestellt. Bei den Haftmechanismen werden neue Ergebnisse uber den Rauhigkeitseinflus und die Abstandsabhangigkeit gebracht, die eine Korrektur seitheriger Vorstellungen verlangen. Die Zugfestigkeit und Dehnung von Feuchtagglomeraten ist weitgehend aufgeklart. Die Scherfestigkeit hangt stark vom Feuchtigkeitsgehalt ab. Die Methoden der Haufwerksmechanik ermoglichen eine Vorausberechnung des Walzenkompaktierens nach Johanson. Fragen des Tablettierens, der Agglomerationskinetik unter Berucksichtigung elektrostatischer Phanomene und der Aufbaugranulation feuchter Haufwerke werden behandelt.
194 citations
TL;DR: In this article, the temperature distribution around the crack tip has been calculated and the temperatures are dependent on the radius of the heat source and the crack velocity, and the very high temperatures computed lead to the supposition that the observed light emission during fast fracture is of thermal origin.
Abstract: T he high energy concentration at the tip of a running crack leads to irreversible deformations, and a great amount of the deformation energy is set free as heat. Assuming that this moving heat source is of circular shape, the temperature distribution around the crack tip has been calculated. The temperatures are dependent on the radius of the heat source and the crack velocity. Some examples for the material glass are given. The very high temperatures computed lead to the supposition that the observed light emission during fast fracture is of thermal origin.
118 citations
TL;DR: In this paper, a generalized correlation is proposed for the values of effective interfacial area duing Vaporization, Absorption with and without Chemical Reaction and the value of wetted surface area in terms of dimensionless numbers.
107 citations
TL;DR: In this article, the authors describe methods that allow for an efficient evaluation of two-electron integrals over contracted Gaussian lobe functions by avoiding the computation of integrals that are: 1. sufficiently small on numerical reasons, 2. zero by symmetry, 3. identical to other integrals by symmetry.
Abstract: Methods are described that allow for an efficient evaluation of two-electron integrals over contracted Gaussian lobe functions. The improvement in computational speed is achieved by avoiding the computation of integrals that are: 1. sufficiently small on numerical reasons, 2. zero by symmetry, 3. identical to other integrals by symmetry. Examples of the effectiveness of these techniques are included. We also report the timings for a further processing of two-electron integrals in a Hartree Fock and correlation energy computation.
89 citations
TL;DR: In this paper, the accuracy of several crack propagation equations published in recent years are tested on crack propagation behavior of fourteen metallic materials and four equations based on different crack propagation models yield reasonably good approximations of measured behaviour.
77 citations
TL;DR: The work equivalent of any material is defined as the maximum amount of shaft work or electrical energy which can possibly be obtained from it when heat and matter are exchanged with the environment as discussed by the authors.
TL;DR: In this paper, the electrochemical behavior of pure iron in alkaline sulphate solutions was studied using cyclic voltammetry atT = 298 K. At starting potentials in the range of hydrogen evolution and at maximum activation conditions, the voltammograms showed three anodic current maxima and two cathodic ones.
Abstract: The electrochemical behaviour of pure iron in alkaline sulphate solutions was studied using cyclic voltammetry atT = 298 K. It has been found that the results depend on the polarization pre-treatment of the electrode and the activation state of its surface. At starting potentials in the range of hydrogen evolution and at maximum activation conditions, the voltammograms show three anodic current maxima and two cathodic ones. A correlation between these different maxima is given. The electrode processes, which may take place at these maxima, are discussed in terms of possible iron dissolution mechanisms.
TL;DR: In this paper, a statistical model for atoms in a very strong magnetic field was built, starting from the assumption that the Coulomb motion of the atomic electrons is adiabatically slow with respect to their magnetic motion.
Abstract: A statistical model for atoms in a very strong magnetic field (${10}^{12}$-${10}^{14}$ G) may be built, starting from the assumption that the Coulomb motion of the atomic electrons is adiabatically slow with respect to their magnetic motion. Within this framework, the binding energies and radii, as well as the ionization energies of singly and doubly ionized atoms, are computed for atomic numbers $5\ensuremath{\le}Z\ensuremath{\le}100$ in the Thomas-Fermi case, and for $5\ensuremath{\le}Z\ensuremath{\le}70$ in the Thomas-Fermi-Dirac case. Possible astrophysical implications may concern the emission of electrons and ions from the surface of pulsars, the abundances of the elements in the cosmic radiation, and the properties of the condensed matter forming the outer crust of magnetic neutron stars.
TL;DR: In this article, the Ericson-Ericson optical potential for the π-nucleuss-wave interaction was extended to be applicable also for light nuclei and terms of order A−1 were evaluated and the (π2N) dispersion was considered.
Abstract: The Ericson-Ericson optical potential for theπ-nucleuss-wave interaction was extended to be applicable also for light nuclei. In particular, terms of order A−1 were evaluated and the (π2N) dispersion was considered. From comparison with experimental data we found that considerable improvement could be achieved by introducing terms of order A−1. The (π2N) dispersion was found to be repulsive and of the same magnitude as the absorption. The (πN) scattering lengths were deduced to be α3−α1=0.258±0.008mπ−1 and α1+2α3=−0.018±0.008mπ−1.
TL;DR: In this paper, the lowest singlet and triplet states of the radicals CH2, CHF, CF2, and CHCH3 were investigated both in SCF and IEPA approximation (independent electron pair approach) to account for electron correlation.
Abstract: The lowest singlet and triplet states of the radicals CH2, CHF, CF2, and CHCH3 have been investigated both in SCF and IEPA approximation (“independent electron pair approach” to account for electron correlation). The SCF calculations yield triplet ground states for CH2, CHF, and CHCH3, and a singlet ground state for CF2. Electron correlation stabilizes the singlet state by about 14 kcal/mole with respect to the triplet for all four radicals leading to a singlet ground state also for CHF. The final triplet-singlet energy separations are 10, 6, −11, −47 kcal/mole for CH2, CHCH3, CHF, CF2, respectively. Values for equilibrium bond angles, ionization potentials and bond energies are also given.
TL;DR: In this article, the 13C-NMR spectra of dehydrogenation polymers (DHPs), which were obtained under different conditions from coniferyl alcohol (Zulauf-” and Zutropf-DHP), were compared with spruce lignin.
Abstract: Die 13C-NMR-Spektren von Dehydrierungspolymerisaten (DHPs), die unter verschiedenen Bedingungen aus Coniferylalkohol erhalten wurden (“Zulauf-” und “Zutropf-DHP”), werden mit dem 13C-NMR-Spektrum des Fichtenlignins verglichen. Man findet eine Abhangigkeit der Linienintensitaten von den Herstellungsbedingungen der DHPs. Durch Anpassung der in-vitro- an die in-vivo-Bedingungen verschieben sich die Linienintensitaten in den DHP-Spektren in Richtung auf diejenigen des Ligninspektrums. Die Ergebnisse bestatigen den von Freudenberg postulierten Bildungsweg von naturlichem Lignin im Sinne einer Dehydrierungspolymerisation von p-Hydroxy-zimtalkoholen.
The 13C-NMR spectra of dehydrogenation polymers (DHPs), which were obtained under different conditions from coniferyl alcohol (“Zulauf-” and “Zutropf-DHP”), are compared with the 13C-NMR spectrum of spruce lignin. A relationship is found between the signal intensities and the conditions of preparation of the DHPs. Adaptation of the in-vitro to the in-vivo conditions shifts the signal intensities of the DHP-spectra towards those of the lignin spectrum. The results confirm Freudenberg's proposal that lignin is formed by a dehydrogenative polymerisation of p-hydroxy-cinnamic alcohols.
TL;DR: In this paper, the energy shift due to strong interaction effects of the pionic 1s level in liquid 4 He was determined to be −75.7±2.0 eV.
TL;DR: In this paper, the potential advantages of 13C-noise decoupled spectroscopy over 1H-spectroscopy for the quantitative investigation of molecular dynamic process is discussed.
Abstract: The potential advantages of 13C-(1H-noise decoupled) spectroscopy (in the Fourier transform mode) over 1H-spectroscopy for the quantitative investigation of molecular dynamic process is discussed. The Cope rearrangement in bullvalene, an example of complex exchange of spins over different magnetic sites, has been studied by both kinds of spectroscopy as a test.
TL;DR: In this article, an algebra with supersymmetry generators and an internal SU(2) was constructed, and the action of the SU group on a fundamental superfield was analyzed.
TL;DR: In this paper, extended Gaussian-type basis sets were used to compute the reaction energy of BH3, B2H6, LiH, and Li2H2 in their respective equilibrium geometries.
Abstract: Results of rigorous computations employing extended Gaussian-type basis sets are reported for BH3, B2H6, LiH, and Li2H2 in their respective equilibrium geometries. The dimerization energy of BH3 is calculated as −20.7 kcal/mol within the Hartree-Fock approximation and as −36.6 kcal/mol if electron correlation is included. The corresponding results for the dimerization of LiH are −47.3 kcal/mol and −48.3 kcal/mol. Partitioning of the correlation energy contributions allows to attribute the effect of electron correlation to the increase of next neighbour bond interactions on the dimerization of BH3 and LiH. The difficulties of accurate computations of reaction energies are discussed in detail.
TL;DR: In this article, the tetrasubstituierten [2.2]paracyclophanes 4a, e are formed by cycloaddition of the symmetrical acetylene derivatives 2a to 1,2,4,5-hexatetraene (1), and their constitution and configuration is established by spectroscopic methods, degradation and pyrolysis experiments.
Abstract: Die tetrasubstituierten [2.2]Paracyclophane 4a – e werden durch Cycloaddition der symmetrischen Acetylenderivate 2a – e an 1,2,4,5-Hexatetraen (1) dargestellt und ihre Konstitution und Konfiguration durch spektroskopische Methoden. Abbau- und Pyrolyseversuche bewiesen. Der Tetramethylester 4a wird zum Tetraalkohol 4g reduziert und die Tetracarbonsaure 4c in das Bisanhydrid 4f bzw. [2.2] Paracyclophan (4h) ubergefuhrt. Bei der Anlagerung von Propiolsaure-methylester (5a) an 1 werden alle isomeren disubstituierten [2.2]paracyclophanes 6 erhalten. Weitere symmetrische und unsymmetrische Acetylenderivate reagieren nicht mit 1.
Preparation of [2.2]Paracyclophanes by Addition of Acetylene Derivatives to 1,2,4,5-Hexatetraene
The tetrasubstituted [2.2]paracyclophanes 4a – e are formed by cycloaddition of the symmetrical acetylene derivatives 2a – e to 1,2,4,5-hexatetraene (1), and their constitution and configuration is established by spectroscopic methods, degradation and pyrolysis experiments. The tetramethyl ester 4a is reduced to the tetraalcohol 4g, and the tetracarboxylic acid 4c is converted to the bisanhydride 4f and [2.2] paracyclophanes (4h), respectively. All possible disubstituted [2.2] paracyclophanes 6 are obtained when methyl propiolate (5a) is added to. 1, whereas further symmetrical and unsymmetrical acetylene derivatives do not react with 1.
TL;DR: A transition is hazard-free iff the transient switching function is unate in the transition subcube with respect to the initial and final vertices, and a transition is hazards in feedback-free combinational circuits when the transient input variable can change more than once.
Abstract: Transients in combinational circuits are approached through an analysis of the transition process in a pure delay circuit model that completely separates delay from structure and logic. During any transition, only monotonically increasing sequences of transient input vertices can occur because no transient input variable can change more than once. This restriction to the shortest trajectories through the transition subcube yields a common criterion for all types of hazards in feedback-free combinational circuits: a transition is hazard-free iff the transient switching function is unate in the transition subcube with respect to the initial and final vertices.
TL;DR: In this paper, the effect of the cobalt binder-phase content on the microstructure and certain mechanical properties of TaCCo alloys prepared by liquid-phase sintering was investigated.
28 Nov 1974
TL;DR: In this article, the authors investigated the possibility of interpreting seismic arrivals from the lower lithosphere in France in terms of the fine-grained structure of the lower-lithosphere and the resulting model consists of alternating high and low velocity layers.
Abstract: Observations of seismic arrivals from the lower lithosphere in France revealed a low mean velocity of observed first arrivals of about 8.1 km/s between 150 and more than 1000 km distance and several high velocity phases with apparent velocities between about 8.2 and 8.6 km/s. Each one of these high velocity phases is only observed over a range of about 100 or 200 km. The possibility of interpreting these phenomena in terms of fine structure of the lower lithosphere is investigated. The resulting model consists of alternating high and low velocity layers. No first order discontinuities seem to exist between these layers. A reliable quantitative estimate of the thickness of these high and low velocity zones can only be obtained by a joint travel time and amplitude study.
TL;DR: Available methods of eliminating the directional ambiguity of Laser Doppler anemometers are reviewed, covering frequency shifting of the incident and scattered light beams, the use of beams with different polarization properties, and employment of multicolor laser beams.
Abstract: Laser Doppler anemometry permits, in principle, the measurement of both magnitude and direction of components of a particle’s velocity vector. Most exiting anemometers, however, permit measurements only with a directional ambiguity of 180°, resulting in errors in certain flow fields. Available methods of eliminating the directional ambiguity of Laser Doppler anemometers are reviewed, covering frequency shifting of the incident and scattered light beams, the use of beams with different polarization properties, and employment of multicolor laser beams. The advantages and disadvantages of existing methods are summarized, and suggestions for alterations are made. Different techniques used to remove the pedestal of laser Doppler anemometer signals are also reviewed. Optical techniques should be employed in any advanced optical anemometer system to avoid dynamic range limitations by electronic bandpass filters. Suggestions are made for advanced optical anemometers employing multielement avalanche photodiodes that can be used for simultaneous measurements of two velocity components. These anemometers incorporate devices to sense the direction of the velocity components and to eliminate optically the pedestal of laser Doppler signals.
TL;DR: In this article, the Brueckner model was used to analyze pion-deuteron scattering at medium energies, with particular attention being paid to the kinematic approximations that have to be made.
TL;DR: In this article, the chemical nature of the water soluble pigments of Hygrocybe is investigated, showing a close biogenetic relationship to betalamic acid, a pigment recently isolated from Amanita muscaria.
Abstract: Abstract Sporophores of Hygrocybe species (Agaricales) contain muscaflavin, a pigment recently isolated from Amanita muscaria. Spectroscopic and chemical evidence for its dihydroazepine structure 5a is presented, indicating a close biogenetic relationship to betalamic acid 6a. The chemical nature of the water soluble pigments of Hygrocybe is dis cussed
TL;DR: It is seen that nondegeneracy is closely related to a generalized version of the problem ''represent a given integer @l >= o by means of integer weights g,...,g"r >= 0 via @s^r" @r="1a"@rg"@[email protected] such that the integer coefficients a"@r satisfy 0= 0.
TL;DR: In this paper, the galvanostatic double pulse method was used to investigate the kinetics of the Cu/Cu 2+ electrode, and the results indicated that the anodic dissolution or cathodic deposition of polycrystalline copper takes place mainly by a direct charge transfer mechanism at growth sites.