Dynamics of a linear beam with an attached local nonlinear energy sink

We provide numerical evidence of passive and broadband targeted energy transfer from a linear flexible beam under shock excitation to a local essentially nonlinear lightweight attachment that acts, in essence, as nonlinear energy sink—NES. It is shown that the NES absorbs shock energy in a one-way, irreversible fashion and dissipates this energy locally, without 'spreading' it back to the linear beam. Moreover, we show numerically that an appropriately designed and placed NES can passively absorb and locally dissipate a major portion of the shock energy of the beam, up to an optimal value of 87%. The implementation of the NES concept to the shock isolation of practical engineering structures and to other applications is discussed

A high order qq-difference equation for qq-Hahn multiple orthogonal polynomials

A high order linear $q$-difference equation with polynomial coefficients having $q$-Hahn multiple orthogonal polynomials as eigenfunctions is given. The order of the equation is related to the number of orthogonality conditions that these polynomials satisfy. Some limiting situations when $q\to1$ are studied. Indeed, the difference equation for Hahn multiple orthogonal polynomials given in \cite{Lee} is corrected and obtained as a limiting case

Extraction of biological hydroxyapatite from bovine bone for biomedical applications

Current biomedical field demands intensive research on cost-effective and high availability materials to fulfil its various applications. Owing to its similar characteristic to human bone, biological hydroxyapatite (HAp) has been used as an alternative in bone replacement and implantation. In this study, biological HAp was extracted from bovine bones via calcination. Powders calcined at 700 °C and 900 °C showed the presence of HAp. The field emission scanning electron microscope (FESEM) analysis shows that the irregular morphology emerged and the size was increasing as the calcination temperature increased. By increasing the temperature of 1100 °C, β-TCP (beta-tricalcium phosphate) started to develop and influenced the ratio of Ca/P. At 900 °C, the Ca/P ratio obtained was 1.70, and closest to the theoretical ratio of Ca/P. The presence of trace elements like Ca, Mg, Sr Na, K and Zn in all samples are proved via energy-dispersive X-ray spectroscopy (EDS) analysis, and these elements help to enhance the bioactivity hence make it a good alternative in biomedical applications

Second Order Power Corrections in the Heavy Quark Effective Theory I. Formalism and Meson Form Factors

In the heavy quark effective theory, hadronic matrix elements of currents between two hadrons containing a heavy quark are expanded in inverse powers of the heavy quark masses, with coefficients that are functions of the kinematic variable $v\cdot v'$. For the ground state pseudoscalar and vector mesons, this expansion is constructed at order $1/m_Q^2$. A minimal set of universal form factors is defined in terms of matrix elements of higher dimension operators in the effective theory. The zero recoil normalization conditions following from vector current conservation are derived. Several phenomenological applications of the general results are discussed in detail. It is argued that at zero recoil the semileptonic decay rates for $B\to D\,\ell\,\nu$ and $B\to D^*\ell\,\nu$ receive only small second order corrections, which are unlikely to exceed the level of a few percent. This supports the usefulness of the heavy quark expansion for a reliable determination of $V_{cb}$.Comment: (34 pages, REVTEX, two postscript figures available upon request), SLAC-PUB-589

The surface chemistry of nanocrystalline MgO catalysts for FAME production:an in situ XPS study of H2O, CH3OH and CH3OAc adsorption

An in situ XPS study of water, methanol and methyl acetate adsorption over as-synthesised and calcined MgO nanocatalysts is reported with a view to gaining insight into the surface adsorption of key components relevant to fatty acid methyl esters (biodiesel) production during the transesterification of triglycerides with methanol. High temperature calcined NanoMgO-700 adsorbed all three species more readily than the parent material due to the higher density of electron-rich (111) and (110) facets exposed over the larger crystallites. Water and methanol chemisorb over the NanoMgO-700 through the conversion of surface O2 − sites to OH− and coincident creation of Mg-OH or Mg-OCH3 moieties respectively. A model is proposed in which the dissociative chemisorption of methanol occurs preferentially over defect and edge sites of NanoMgO-700, with higher methanol coverages resulting in physisorption over weakly basic (100) facets. Methyl acetate undergoes more complex surface chemistry over NanoMgO-700, with C–H dissociation and ester cleavage forming surface hydroxyl and acetate species even at extremely low coverages, indicative of preferential adsorption at defects. Comparison of C 1s spectra with spent catalysts from tributyrin transesterification suggest that ester hydrolysis plays a key factor in the deactivation of MgO catalysts for biodiesel production

Designing novel applications for emerging multimedia technology

Current R&D in media technologies such as Multimedia, Semantic Web and Sensor Web technologies are advancing in a fierce rate and will sure to become part of our important regular items in a 'conventional' technology inventory in near future. While the R&D nature of these technologies means their accuracy, reliability and robustness are not sufficient enough to be used in real world yet, we want to envision now the near-future where these technologies will have matured and used in real applications in order to explore and start shaping many possible new ways these novel technologies could be utilised. In this talk, some of this effort in designing novel applications that incorporate various media technologies as their backend will be presented. Examples include novel scenarios of LifeLogging application that incorporate automatic structuring of millions of photos passively captured from a SenseCam (wearable digital camera that automatically takes photos triggered by environmental sensors) and an interactive TV application incorporating a number of multimedia tools yet extremely simple and easy to use with a remote control in a lean-back position. The talk will conclude with remarks on how the design of novel applications that have no precedence or existing user base should require somewhat different approach from those suggested and practiced in conventional usability engineering methodology

Torque magnetometry of an amorphous-alumina/strontium-titanate interface

We report torque magnetometry measurements of an oxide heterostructure consisting of an amorphous Al2O3 thin film grown on a crystalline SrTiO3 substrate (a-AO/STO) by atomic layer deposition. We find a torque response that resembles previous studies of crystalline LaAlO3/SrTiO3 (LAO/STO) heterointerfaces, consistent with strongly anisotropic magnetic ordering in the plane of the interface. Unlike crystalline LAO, amorphous Al2O3 is nonpolar, indicating that planar magnetism at an oxide interface is possible without the strong internal electric fields generated within the polarization catastrophe model. We discuss our results in the context of current theoretical efforts to explain magnetism in crystalline LAO/STO.Chemistry and Chemical Biolog

The Role of the Primary Visual Cortex in Higher Level Vision

In the classical feed-forward, modular view of visual processing, the primary visual cortex (area V1) is a module that serves to extract local features such as edges and bars. Representation and recognition of objects are thought to be functions of higher extrastriate cortical areas. This paper presents neurophysiological data that show the later part of V1 neurons’ responses reflecting higher order perceptual computations related to Ullman’s (Cognition 1984;18:97–159) visual routines and Marr’s (Vision NJ: Freeman 1982) full primal sketch, 2Image D sketch and 3D model. Based on theoretical reasoning and the experimental evidence, we propose a possible reinterpretation of the functional role of V1. In this framework, because of V1 neurons’ precise encoding of orientation and spatial information, higher level perceptual computations and representations that involve high resolution details, fine geometry and spatial precision would necessarily involve V1 and be reflected in the later part of its neurons’ activities.Mathematic