827 research outputs found

    Blending in Future Space-based Microlensing Surveys

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    We investigate the effect of blending in future gravitational microlensing surveys by carrying out simulation of Galactic bulge microlensing events to be detected from a proposed space-based lensing survey. From this simulation, we find that the contribution of the flux from background stars to the total blended flux will be equivalent to that from the lens itself despite the greatly improved resolution from space observations, implying that characterizing lenses from the analysis of the blended flux would not be easy. As a method to isolate events for which most of the blended flux is attributable to the lens, we propose to use astrometric information of source star image centroid motion. For the sample of events obtained by imposing a criterion that the centroid shift should be less than three times of the astrometric uncertainty among the events for which blending is noticed with blended light fractions fB>0.2f_{\rm B}>0.2, we estimate that the contamination of the blended flux by background stars will be less than 20% for most (∌90\sim 90%) of the sample events. The expected rate of these events is ≳700\gtrsim 700 events/yr, which is large enough for the statistical analysis of the lens populations.Comment: total 6 pages, including 5 figures, ApJ, in pres

    Many Rivers to Cross: Evaluating the Benefits and Limitations of Strategic Environmental Assessment for the Koshi River Basin

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    This paper assesses the value of using Strategic Environmental Assessment (SEA) to account for the spatially and temporally diverse and diffuse impacts of hydropower development in South Asia’s Koshi basin. A policy and practice review and key stakeholder interviews identified opportunities for SEA to improve existing planning procedures, but also barriers to effective adoption. Whilst stakeholders are interested in employing SEA to evaluate cumulative impacts, institutional blockages and an economic development imperative for power generation leave little space for consideration of alternative scenarios as part of SEA. The analysis is conducted through the formulation and application of a conceptual framework for SEA best practice which is then used to identify priority next-steps for SEA in the region

    Relationship among seam strength, weft-way fabric strength and stitch density of B. Twill jute bag

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    The influence of weft-way fabric strength and stitch density on the seam strength of B. Twill jute bag has been studied. Study reveals that a correlation exists among seam strength, weft-way fabric strength and stitch density of B. Twill jute bags sewn with herakle stitches. A regression equation for seam strength as a function of two factors namely weft-way fabric strength and stitch density has been established

    RGB vegetation indices applied to grass monitoring: a qualitative analysis

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    ArticleIn developing countries such as Brazil, research on low-cost remote sensing and computational techniques become essential for the development of precision agriculture (PA), and improving the quality of the agricultural products. Faced with the scenario of increasing production of emerald grass (Zoysia JapĂŽnica) in Brazil, and the value added the quality of this agricultural product. The objective of this work was to evaluate the performance of RGB (IV) vegetation indices in the identification of exposed soil and vegetation. The study was developed in an irrigated area of 58 ha cultivated with emerald grass at Bom Sucesso, Minas Gerais, Brazil. The images were obtained by a RGB digital camera coupled to an remotely piloted aircraft. The flight plan was setup to take overlapping images of 70% and the aircraft speed was 10 m s -1 . Six RGB Vegetation index (MGVRI, GLI, RGBVI, MPRI, VEG, ExG) were evaluated in a mosaic resulting from the images of the study area. All of the VIs evaluated were affected by the variability of lighting conditions in the area but MPRI and MGVRI were the ones that presented the best results in a qualitative evaluation regarding the discrimination of vegetation and soil

    Specially treated woven jute geotextiles for river bank protection

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    In this paper, studies on treatment of jute geotextile with isothiazolinone and fluorocarbon derivatives to impart antimicrobial and water repellent property have been reported for its improved end use specific performance. It is observed that the treated jute geotextile possesses higher durability in water as well as soil-water ambience

    Density Perturbations in the Brans-Dicke Theory

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    We analyse the fate of density perturbation in the Brans-Dicke Theory, giving a general classification of the solutions of the perturbed equations when the scale factor of the background evolves as a power law. We study with details the cases of vacuum, inflation, radiation and incoherent matter. We find, for the a negative Brans-Dicke parameter, a significant amplification of perturbations.Comment: 26 pages, latex fil

    First Principles Study of Zn-Sb Thermoelectrics

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    We report first principles LDA calculations of the electronic structure and thermoelectric properties of ÎČ\beta -Zn4_{4}Sb3_{3}. The material is found to be a low carrier density metal with a complex Fermi surface topology and non-trivial dependence of Hall concentration on band filling. The band structure is rather covalent, consistent with experimental observations of good carrier mobility. Calculations of the variation with band filling are used to extract the doping level (band filling) from the experimental Hall number. At this band filling, which actually corresponds to 0.1 electrons per 22 atom unit cell, the calculated thermopower and its temperature dependence are in good agreement with experiment. The high Seebeck coefficient in a metallic material is remarkable, and arises in part from the strong energy dependence of the Fermiology near the experimental band filling. Improved thermoelectric performance is predicted for lower doping levels which corresponds to higher Zn concentrations.Comment: 5 pages, 6 figure

    Formal Verification of Security Model Using SPR Tool

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    In this paper, formal verification methodologies and the SPR (Safety Problem Resolver) model checking tool are used for verifying a security model's safety. The SPR tool makes it possible to analyze security issues on security systems based on the access control model. To illustrate this approach, a case study of the Simple Access Control Model (SACM) is used and specific safety problems of the security model are analyzed using the SPR tool
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