9,578 research outputs found

    Method of fabricating a photovoltaic module of a substantially transparent construction

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    A method characterized by the steps of positioning a plurality of uniformly dimensioned photovoltaic cells in registered relation with a plurality of openings formed in a planar tool is disclosed. The method allows acess to the P contact surface of each of the cells. The steps of the method are: (1) connecting the N contact surface of alternate cells to the P contact surface of the cells interposed therebetween, (2) removing therefrom residue of solder flux, (3) applying to the N contact surfaces of the cells a transparent adhesive, (4) placing a common transparent cover plate in engaged relation with the adhesive, (5) placing a film over the circular openings for hermetically sealing the openings, and (6) establishing a vacuum between the film and the cover plate

    Optimization of Al/AlOx/AlAl/AlO_x/Al-Layer Systems for Josephson Junctions from a Microstructure Point of View

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    Al/AlOx/AlAl/AlO_x/Al-layer systems are frequently used for Josephson junction-based superconducting devices. Although much work has been devoted to the optimization of the superconducting properties of these devices, systematic studies on influence of deposition conditions combined with structural analyses on the nanoscale are rare up to now. We have focused on the optimization of the structural properties of Al/AlOx/AlAl/AlO_x/Al-layer systems deposited on Si(111) substrates with a particular focus on the thickness homogeneity of the AlOxAlO_x-tunnel barrier. A standard high-vacuum electron-beam deposition system was used and the effect of substrate pretreatment, different Al-deposition temperatures and Al-deposition rates was studied. Transmission electron microscopy was applied to analyze the structural properties of the Al/AlOx/AlAl/AlO_x/Al-layer systems to determine the thickness homogeneity of the AlOxAlO_x layer, grain size distribution in the Al layers, Al-grain boundary types and the morphology of the Al/AlOxAl/AlO_x interface. We show that the structural properties of the lower Al layer are decisive for the structural quality of the whole Al/AlOx/AlAl/AlO_x/Al-layer system. Optimum conditions yield an epitaxial Al(111) layer on a Si(111) substrate with an Al-layer thickness variation of only 1.6 nm over more than 10 ÎĽm\mu m and large lateral grain sizes up to 1 ÎĽm\mu m. Thickness fluctuations of the AlOxAlO_x-tunnel barrier are minimized on such an Al layer which is essential for the homogeneity of the tunnel current. Systematic variation of the Al-deposition rate and deposition temperature allows to develop an understanding of the growth mechanisms

    Labor Cost and Value of Citrus Operations with Alternative Technology: Enterprise DCF Approach

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    The prospect of immigration policy reform has renewed growers’ concerns of serious labor shortages and cost increases given that a large portion of the workforce is unauthorized for U.S. employment. This concern of labor shortages and cost increases is more serious for specialty crop agriculture which is highly labor intensive. Specialty crop growers may address the problem in various ways, but likely options include adoption of mechanical harvesting. In the current paper we study the citrus industry case and estimate the value for two operational modes (hand and mechanical harvesting) using the enterprise discounted cash flow (DCF) approach. Further we implement a simulation to forecast how the value for each operational mode would change with a change in cost scenario.Value, Enterprise DCF approach, Labor cost, Citrus operations, Mechanization, Agricultural Finance, Labor and Human Capital, Q14, J43,

    Harvest Cost and Value of Citrus Operations with Alternative Technology: Real Options Approach

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    The prospect of immigration policy reform has renewed growers’ concerns of serious labor shortages and cost increases. These concerns are more serious for specialty crop agriculture, not only because it is highly labor intensive, but also it requires labor in a very short period, particularly at harvest time. Two representative approaches of the investment valuation have been applied to the case of harvesting mechanization for the model citrus grower in Florida. Specifically, we applied the NPV approach and the real options approach (ROA) to processed-market Hamlin orange operations in Southwest Florida.Real options, NPV, mechanization, immigration policy, harvest cost, citrus operations, Agribusiness, Agricultural Finance, Farm Management, Labor and Human Capital, Risk and Uncertainty, Q14 – Agricultural Finance, J43 – Agricultural Labor Markets,

    Motion Analysis Strategy Appropriate for 3D Kinematic Assessment of Children and Adults with Osteogenesis Imperfecta

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    Human motion analysis provides a quantitative means of assessing whole body and segmental motion of subjects with musculoskeletal pathologies. This chapter describes a low cost motion analysis appropriate for complete three-dimensional (3D) assessment of upper and lower extremity kinematics. The system has been designed to support lower cost outreach efforts that require accuracy and resolution on the order of classical fixed lot systems such as Vicon. The focus of this work addresses the assessment needs typically seen in adults and children with osteogenesis imperfect (OI) experiencing ambulatory and upper extremity challenges

    Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits

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    This work is concerned with Al/Al-oxide(AlOx_{x})/Al-layer systems which are important for Josephson-junction-based superconducting devices such as quantum bits. The device performance is limited by noise, which has been to a large degree assigned to the presence and properties of two-level tunneling systems in the amorphous AlOx_{x} tunnel barrier. The study is focused on the correlation of the fabrication conditions, nanostructural and nanochemical properties and the occurrence of two-level tunneling systems with particular emphasis on the AlOx_{x}-layer. Electron-beam evaporation with two different processes and sputter deposition were used for structure fabrication, and the effect of illumination by ultraviolet light during Al-oxide formation is elucidated. Characterization was performed by analytical transmission electron microscopy and low-temperature dielectric measurements. We show that the fabrication conditions have a strong impact on the nanostructural and nanochemical properties of the layer systems and the properties of two-level tunneling systems. Based on the understanding of the observed structural characteristics, routes are derived towards the fabrication of Al/AlOx_{x}/Al-layers systems with improved properties.Comment: 28 pages, 4 figure

    The concentration-mass relation of clusters of galaxies from the OmegaWINGS survey

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    The relation between a cosmological halo concentration and its mass (cMr) is a powerful tool to constrain cosmological models of halo formation and evolution. On the scale of galaxy clusters the cMr has so far been determined mostly with X-ray and gravitational lensing data. The use of independent techniques is helpful in assessing possible systematics. Here we provide one of the few determinations of the cMr by the dynamical analysis of the projected-phase-space distribution of cluster members. Based on the WINGS and OmegaWINGS data sets, we used the Jeans analysis with the MAMPOSSt technique to determine masses and concentrations for 49 nearby clusters, each of which has ~60 spectroscopic members or more within the virial region, after removal of substructures. Our cMr is in statistical agreement with theoretical predictions based on LambdaCDM cosmological simulations. Our cMr is different from most previous observational determinations because of its flatter slope and lower normalization. It is however in agreement with two recent cMr obtained using the lensing technique on the CLASH and LoCuSS cluster data sets. In the future we will extend our analysis to galaxy systems of lower mass and at higher redshifts.Comment: Astronomy & Astrophysics in press. 11 pages, 6 figure

    Emission Line Galaxies and Active Galactic Nuclei in WINGS clusters

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    We present the analysis of the emission line galaxies members of 46 low redshift (0.04 < z < 0.07) clusters observed by WINGS (WIde-field Nearby Galaxy cluster Survey, Fasano et al. 2006). Emission line galaxies were identified following criteria that are meant to minimize biases against non-star forming galaxies and classified employing diagnostic diagrams. We have examined the emission line properties and frequencies of star forming galaxies, transition objects and active galactic nuclei (AGNs: LINERs and Seyferts), unclassified galaxies with emission lines, and quiescent galaxies with no detectable line emission. A deficit of emission line galaxies in the cluster environment is indicated by both a lower frequency with respect to control samples, and by a systematically lower Balmer emission line equivalent width and luminosity (up to one order of magnitude in equivalent width with respect to control samples for transition objects) that implies a lower amount of ionised gas per unit mass and a lower star formation rate if the source is classified as Hii region. A sizable population of transition objects and of low-luminosity LINERs (approx. 10 - 20% of all emission line galaxies) is detected among WINGS cluster galaxies. With respect to Hii sources they are a factor of approx. 1.5 more frequent than (or at least as frequent as) in control samples. Transition objects and LINERs in cluster are most affected in terms of line equivalent width by the environment and appear predominantly consistent with "retired" galaxies. Shock heating can be a possible gas excitation mechanism able to account for observed line ratios. Specific to the cluster environment, we suggest interaction between atomic and molecular gas and the intracluster medium as a possible physical cause of line-emitting shocks.Comment: Astronomy and Astrophysics, accepte
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