A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

Several techniques were used to study pretreated Ti 6-4 surfaces including scanning electron microscopy (SEM), electron spectroscopy of chemical analysis (ESCA), and, reflectance visible spectroscopy. Each pretreatment type gave a characteristic surface morphology as seen by SEM. Elemental analysis of the Ti 6-4 surfaces was done using ESCA. Trace residual contaminants from particular chemical pretreatments were identified readily. Results indicate that reflectance visible spectroscopy using indicator dyes placed on Ti 6-4 surfaces appears to be a feasible approach to establish surface acidity. Differences in surface acidity were observed using bromthymol blue on Ti 6-4 surfaces pretreated by two different methods

An investigation of adhesive/adherend and fiber matrix interactions

Research during the report period focused on continued scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) of lap shear samples and flatwise tensile specimens and on the surface characterization of TiO2, Ti 6-4, and Ti powders with particular emphasis on their interaction with primer solutions of both polyphenylquinoxaline and LaRC-13 polyimide. The use of SEM and XPS in the analysis of Ti 6-4 adherend surfaces is described as well as differences in Ti 6-4 surface composition after different chemical pretreatments. Analysis of fractured surfaces is used to established the failure mode. The surface acidity of Ti 6-4 coupons can be established by reflectance visible spectroscopy using indicator dyes

A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

Pretreated and primed Ti 6-4 surfaces were characterized by scanning electron microscopy/energy dispersive analysis of X-rays (SEM/EDAX) and electron spectroscopy for chemical analysis (ESCA). Fractured lap shear bonded Ti 6-4 specimens were also characterized by SEM/EDAX and ESCA. A number of surface techniques were used to characterize Ti02 powders

Wavelet-based Faraday Rotation Measure Synthesis

Faraday Rotation Measure (RM) Synthesis, as a method for analyzing multi-channel observations of polarized radio emission to investigate galactic magnetic fields structures, requires the definition of complex polarized intensity in the range of the negative lambda square. We introduce a simple method for continuation of the observed complex polarized intensity into this domain using symmetry arguments. The method is suggested in context of magnetic field recognition in galactic disks where the magnetic field is supposed to have a maximum in the equatorial plane. The method is quite simple when applied to a single Faraday-rotating structure on the line of sight. Recognition of several structures on the same line of sight requires a more sophisticated technique. We also introduce a wavelet-based algorithm which allows us to consider a set of isolated structures. The method essentially improves the possibilities for reconstruction of complicated Faraday structures using the capabilities of modern radio telescopes.Comment: 5 pages, 5 figures, accepted for publication in MNRAS Letter

Red-giant stars in eccentric binaries

The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs

The New Zealand Strong Motion Earthquake Recorder Network

The network of strong-motion earthquake recorders, maintained throughout New Zealand by the Engineering Seismology Section of the Department of Scientific and Industrial Research, is described. The instruments are either deployed as ground instruments to measure potential earthquake attack on structures, or in structures, e.g. buildings, dams and industrial installations, to record structural response. Details are given of installation of instruments , maintenance, laboratory work, record retrieval and digitisation, costs and staffing for the network. Future developments mooted include an improved digitising system, the introduction of an improved version of the existing mechanical-optical instrument in 1979, and, in the long term, the introduction of an entirely new digital recorder, having an electrical output from its accelerometers, which will make possible the transmission of data by telephone or radio link

Magnetic field structures of galaxies derived from analysis of Faraday rotation measures, and perspectives for the SKA

The forthcoming new-generation radio telescope SKA (Square Kilometre Array) and its precursors will provide a rapidly growing number of polarized radio sources. Our analysis aims on what can be learned from these sources concerning the structure and evolution of magnetic fields of external galaxies. Recognition of magnetic structures is possible from Faraday rotation measures (${\rm RM}$) towards background sources behind galaxies. We construct models for the ionized gas and magnetic field patterns of different azimuthal symmetry (axisymmetric, bisymmetric and quadrisymmetric spiral, and superpositions) plus a halo magnetic field. \RM fluctuations with a Kolmogorov spectrum due to turbulent fields and/or fluctuations in ionized gas density are superimposed. Assuming extrapolated number density counts of polarized sources, we generate a sample of \RM values within the solid angle of the galaxy. Applying various templates, we derive the minimum number of background sources and the minimum quality of the observations. For a large number of sources, reconstruction of the field structure without precognition becomes possible. Any large-scale regular component of the magnetic field can be clearly recognized from \RM data with help of the $\chi^2$ criterium. Under favourite conditions, about a few dozens of polarized sources are sufficient for a reliable result.Comment: 16 pages, 18 figures, accepted for publication in A&