BOOK REVIEWS

Book reviewed in this article: From Stone to Star: A View of Modern Geology, Claude J. Allègre (translated by Deborah Kurmes Van Dam) The Chosen Primate, Adam Kuper     

Anwendung von Radioisotopen zur Untersuchung von Metalloberflächen nach mechanischer Bearbeitung in einem metallhaltigen Elektrolyten

Zur Unlersuchung des Materia1transports aus einem Elektrolyten in eine feste Metallprobe während mechanischer Bearbeitung wurde ein Schichtabtragungsverfahren mit Messung der Restaktivität eingesetzt. Die einzelnen abgetragenen Schichten waren etwa 1 μm dick.

Das Verfahren wurde an Cu-Material erprobt, in das ⁶⁵Zn aus einer ZnCl2-Lösung eingedrungen war. Die Probenbearbeitung erfolgte auf tribogalvanischem Wege.     

Love waves in functionally graded piezoelectric materials by stiffness matrix method

A numerical matrix method relative to the propagation of ultrasonic guided waves in functionally graded piezoelectric heterostructure is given in order to make a comparative study with the respective performances of analytical methods proposed in literature. The preliminary obtained results show a good agreement, however numerical approach has the advantage of conceptual simplicity and flexibility brought about by the stiffness matrix method. The propagation behaviour of Love waves in a functionally graded piezoelectric material (FGPM) is investigated in this article. It involves a thin FGPM layer bonded perfectly to an elastic substrate. The inhomogeneous FGPM heterostructure has been stratified along the depth direction, hence each state can be considered as homogeneous and the ordinary differential equation method is applied. The obtained solutions are used to study the effect of an exponential gradient applied to physical properties. Such numerical approach allows applying different gradient variation for mechanical and electrical properties. For this case, the obtained results reveal opposite effects. The dispersive curves and phase velocities of the Love wave propagation in the layered piezoelectric film are obtained for electrical open and short cases on the free surface, respectively. The effect of gradient coefficients on coupled electromechanical factor, on the stress fields, the electrical potential and the mechanical displacement are discussed, respectively. Illustration is achieved on the well known heterostructure PZT-5H/SiO₂, the obtained results are especially useful in the design of high-performance acoustic surface devices and accurately prediction of the Love wave propagation behaviour.     

BOOK REVIEWS

Book reviewed in this article: Fractals: A User's Guide For the Natural Sciences, Harold M. Hastings and George Sugihara How Amazing, Charles Snape and Heather How Puzzling, Charles Snape and Heather Scott Classic Math: History Topics for the Classroom, Art Johnson     

Static finite-energy solutions of gauge fields with separated radial variable

For arbitrary compact gauge group G and real representations of the Higgs fields, we seek static finite-energy solutions for which the radial dependence of the fields is factorized. We find that the gauge fields vanish outside a fixed SO(3) subgroup of G, and that inside SO(3) they reduce to the 't Hooft-Polyakov solution with unit magnetic charge. The Higgs fields may belong to any integer representation of this SO(3).     

Symmetric versus antisymmetric mass matrices in grand unified theories

We point out some interesting consequences of antisymmetric fermionic mass terms in grand unified theories, which follow from the symmetry properties of the Yukawa-type fermion-Higgs interactions. In SU(5), we show that an antisymmetric mass matrix M(u) in the up-quark sector arises when the Higgs 5 is replaced by 45. IOn SO(10), all the fermion sectors are characterized by such mass matrices if the neutrinos are required not to pick up the ordinary fermionic mass scale. In the recently proposed vertical-horizontal symmetric SU(5) × SU(5) scheme, a fully antisymmetric M(u) is naturally accompanied by exactly five zeroth-order massless neutrinos.