Characterization of Epoxy Resin (SU-8) Film Using Thickness-Shear Mode (TSM) Resonator under Various Conditions

Characterization of an epoxy resin film, commonly known as SU-8, is presented using thickness shear mode (TSM) quartz resonator. The impedance-admittance characteristics of the equivalent circuit models of the unperturbed and coated resonators are analyzed to extract the storage modulus and loss modulus (G\u27 and G\u27\u27). Those parameters are needed to establish SU-8 film as an effective wave-guiding layer in the implementation of guided shear-horizontal surface acoustic wave (SH-SAW) sensor platforms. Both cured and uncured polymer films are studied at the fundamental and third harmonic frequencies of the TSM resonators. The storage modulus (G\u27) and loss modulus (G\u27\u27) of the SU-8 film approach constant values of 1.66 × 1010 dyne/cm2 and 6.0 × 108 dyne/cm2, respectively, for relatively thicker films (\u3e20 μm) at a relatively low frequency of 9 MHz. The most accurate values for the extracted shear moduli G (G = G\u27 + jG\u27\u27) are obtained at high thickness where the viscoelastic contribution to the TSM response is substantial. The effect of temperature on the storage and loss moduli is determined for the range of −75 to 40 °C. It is found that the polymer approaches a totally glassy state below −60 °C. Exposure to water appears to follow Fickian diffusion behavior at short times and this exposure also results in changes to both G\u27 and G\u27\u27. However, stability is rapidly reached with exposure to water, indicating relatively lower water absorption, consistent with the extracted diffusion coefficient

Analysis of Liquid-Phase Chemical Detection Using Guided Shear Horizontal-Surface Acoustic Wave Sensors

Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36° rotated Y-cut LiTaO3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the four-layer model. Contributions from mass loading and coating viscoelasticity changes to the sensor response are evaluated, taking into account the added mass, swelling, and plasticization. Chemically sensitive polymers are investigated in the detection of low concentrations (1-60 ppm) of toluene, ethylbenzene, and xylenes in water. A low-ppb level detection limit is estimated from the present experimental measurements. Sensor properties are investigated by varying the sensor geometries, coating thickness combinations, coating properties, and curing temperature for operation in liquid environments. Partition coefficients for polymer-aqueous analyte pairs are used to explain the observed trend in sensitivity for the polymers PMMA, poly(isobutylene), poly(epichlorohydrin), and poly(ethyl acrylate) used in this work

Qualité de l'audit et Satisfaction de l'audité : Chronique d'une Innovation Ordinaire

International audienceThe objective of this research is to examine the role which a quality framework plays in the relationships between the auditor and the auditee. For that, we study the origins of an association gathering nine French audit companies, called the ADACEIP (Association of Development of the Activities of Audit in the Entities of Public Interest) as well as the quality procedure which is settled up through the publication of the quality framework (Statutory Audit Premium). Interviews are conducted with all the ADACEIP members. Their interpretation is based on two branches of sociology. The sociology of professions makes it possible to understand the genesis of the ADACEIP as the assertion of a professionalism turned towards a strong defence of the medium-sized audit companies and as the strategy of survival. The sociology of innovation proposes to interpret the Statutory Audit Premium as a project hustling the established order of a profession where the concept of ‘client satisfaction' is highlighted but seems to compromise the insurance of a constraining and however essential independence. These two theoretical interpretations then lead us to underline the necessarily durable character of the relationship auditor - auditee and to establish a reflexive link between the audit quality and the satisfaction of the auditee. This reflexivity contributes to the idea according to which an audit is the co-product of two actors, the auditor and the auditee.L'objectif de la recherche présentée est d'examiner le rôle que peut jouer un référentiel qualité dans la relation entre l'auditeur et l'audité. Pour cela, nous avons étudié les origines d'une association regroupant neuf cabinets français, l'ADACEIP (Association de Développement des Activités de Commissariat aux comptes dans les Entités d'Intérêt Public), ainsi que la démarche qualité qu'elle a mise en oeuvre à travers la publication d'un référentiel qualité, l'Audit Statutaire Premium. Des entretiens ont été menés avec l'ensemble des membres fondateurs du projet. Leur analyse a mobilisé deux branches de la sociologie. En premier lieu, la sociologie des professions a permis de comprendre la genèse de l'ADACEIP comme une stratégie de survie sur un marché dominé par les Big Four. En second lieu, la sociologie de l'innovation a proposé d'interpréter l'Audit Statutaire Premium comme un projet bousculant l'ordre établi d'une profession où la notion de ‘satisfaction du client' semble compromettre l'assurance d'une indépendance de l'auditeur. Ces deux éclairages théoriques nous amènent à établir un lien réflexif entre la qualité de l'audit et la satisfaction de l'audité. Selon nous, cette réflexivité contribue à l'idée selon laquelle un audit est le coproduit de deux acteurs, l'auditeur et l'audité

Representing moisture fluxes and phase changes in glacier debris cover using a reservoir approach

Due to the complexity of treating moisture in supraglacial debris, surface energy balance models to date have neglected moisture infiltration and phase changes in the debris layer. The latent heat flux (QL) is also often excluded due to the uncertainty in determining the surface vapour pressure. To quantify the importance of moisture on the surface energy and climatic mass balance (CMB) of debris-covered glaciers, we developed a simple reservoir parameterization for the debris ice and water content, as well as an estimation of the latent heat flux. The parameterization was incorporated into a CMB model adapted for debris-covered glaciers. We present the results of two point simulations, using both our new “moist” and the conventional “dry” approaches, on the Miage Glacier, Italy, during summer 2008 and fall 2011. The former year coincides with available in situ glaciological and meteorological measurements, including the first eddy-covariance measurements of the turbulent fluxes over supraglacial debris, while the latter contains two refreeze events that permit evaluation of the influence of phase changes. The simulations demonstrate a clear influence of moisture on the glacier energy and mass-balance dynamics. When water and ice are considered, heat transmission to the underlying glacier ice is lower, as the effective thermal diffusivity of the saturated debris layers is reduced by increases in both the density and the specific heat capacity of the layers. In combination with surface heat extraction by QL, subdebris ice melt is reduced by 3.1% in 2008 and by 7.0% in 2011 when moisture effects are included. However, the influence of the parameterization on the total accumulated mass balance varies seasonally. In summer 2008, mass loss due to surface vapour fluxes more than compensates for the reduction in ice melt, such that the total ablation increases by 4.0 %. Conversely, in fall 2011, the modulation of basal debris temperature by debris ice results in a decrease in total ablation of 2.1 %. Although the parameterization is a simplified representation of the moist physics of glacier debris, it is a novel attempt at including moisture in a numerical model of debris-covered glaciers and one that opens up additional avenues for future research

Qualité de l'audit et Satisfaction de l'audité : Chronique d'une Innovation Ordinaire

L'objectif de la recherche présentée est d'examiner le rôle que peut jouer un référentiel qualité dans la relation entre l'auditeur et l'audité. Pour cela, nous avons étudié les origines d'une association regroupant neuf cabinets français, l'ADACEIP (Association de Développement des Activités de Commissariat aux comptes dans les Entités d'Intérêt Public), ainsi que la démarche qualité qu'elle a mise en oeuvre à travers la publication d'un référentiel qualité, l'Audit Statutaire Premium. Des entretiens ont été menés avec l'ensemble des membres fondateurs du projet. Leur analyse a mobilisé deux branches de la sociologie. En premier lieu, la sociologie des professions a permis de comprendre la genèse de l'ADACEIP comme une stratégie de survie sur un marché dominé par les Big Four. En second lieu, la sociologie de l'innovation a proposé d'interpréter l'Audit Statutaire Premium comme un projet bousculant l'ordre établi d'une profession où la notion de ‘satisfaction du client' semble compromettre l'assurance d'une indépendance de l'auditeur. Ces deux éclairages théoriques nous amènent à établir un lien réflexif entre la qualité de l'audit et la satisfaction de l'audité. Selon nous, cette réflexivité contribue à l'idée selon laquelle un audit est le coproduit de deux acteurs, l'auditeur et l'audité.Audit; Qualité; Sociologie; Profession; Innovation

Nuclear Power: a Hedge against Uncertain Gas and Carbon Prices?

High fossil fuel prices have rekindled interest in nuclear power. This paper identifies specific nuclear characteristics making it unattractive to merchant generators in liberalised electricity markets, and argues that non-fossil fuel technologies have an overlooked à ¢à  à  option valueà ¢à  à  given fuel and carbon price uncertainty. Stochastic optimisation estimates the company option value of keeping open the choice between nuclear and gas technologies. This option value decreases sharply as the correlation between electricity, gas, and carbon prices rises, casting doubt on whether private investorsà ¢à  à  fuel-mix diversification incentives in electricity markets are aligned with the social value of a diverse fuel-mix

Влияние литологии на перераспределение метана в угленосной толще

Розглянутий вплив літології на перерасподіл метану у вугільних пластах на шахтах Красноармійського району Донбасу.The influence of litology on methane re-distribution in coal beds on the mines of Krasnoarmeysk region of Donbas were considered

Spectral State Transitions of the Ultraluminous X-ray Source IC 342 X-1

We observed the Ultraluminous X-ray Source IC 342 X-1 simultaneously in X-ray and radio with Chandra and the JVLA to investigate previously reported unresolved radio emission coincident with the ULX. The Chandra data reveal a spectrum that is much softer than observed previously and is well modelled by a thermal accretion disc spectrum. No significant radio emission above the rms noise level was observed within the region of the ULX, consistent with the interpretation as a thermal state though other states cannot be entirely ruled out with the current data. We estimate the mass of the black hole using the modelled inner disc temperature to be $30~\mathrm{M_{\odot}} \lesssim M\sqrt{\mathrm{cos}i}\lesssim200~\mathrm{M_{\odot}}$ based on a Shakura-Sunyaev disc model. Through a study of the hardness and high-energy curvature of available X-ray observations, we find that the accretion state of X-1 is not determined by luminosity alone.Comment: 10 pages, 5 Figures. MNRAS: Accepted 2014 July 2