13,900 research outputs found

    Detecting and Refactoring Operational Smells within the Domain Name System

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    The Domain Name System (DNS) is one of the most important components of the Internet infrastructure. DNS relies on a delegation-based architecture, where resolution of names to their IP addresses requires resolving the names of the servers responsible for those names. The recursive structures of the inter dependencies that exist between name servers associated with each zone are called dependency graphs. System administrators' operational decisions have far reaching effects on the DNSs qualities. They need to be soundly made to create a balance between the availability, security and resilience of the system. We utilize dependency graphs to identify, detect and catalogue operational bad smells. Our method deals with smells on a high-level of abstraction using a consistent taxonomy and reusable vocabulary, defined by a DNS Operational Model. The method will be used to build a diagnostic advisory tool that will detect configuration changes that might decrease the robustness or security posture of domain names before they become into production.Comment: In Proceedings GaM 2015, arXiv:1504.0244

    Simple Floating Voltage-Controlled Memductor Emulator for Analog Applications

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    The topic of memristive circuits is a novel topic in circuit theory that has become of great importance due to its unique behavior which is useful in different applications. But since there is a lack of memristor samples, a memristor emulator is used instead of a solid state memristor. In this paper, a new simple floating voltage-controlled memductor emulator is introduced which is implemented using commercial off the shelf (COTS) realization. The mathematical modeling of the proposed circuit is derived to match the theoretical model. The proposed circuit is tested experimentally using different excitation signals such as sinusoidal, square, and triangular waves showing an excellent matching with previously reported simulations

    THE HORIZON OF DEVELOPINGTHE EGYPTIAN MARKETING TOURISM IN EU

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    Egypt made a tremendous effort during the last few years to enhance its tourism sectors. This was reflected in the number of tourists who visited Egypt, especially form E.U. and also in the revenue from the tourists who jumped in the recent years.tourism, E.U., Egypt, hotel, history

    Numerical solutions of the compressible 3-D boundary-layer equations for aerospace configurations with emphasis on LFC

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    The application of stability theory in Laminar Flow Control (LFC) research requires that density and velocity profiles be specified throughout the viscous flow field of interest. These profile values must be as numerically accurate as possible and free of any numerically induced oscillations. Guidelines for the present research project are presented: develop an efficient and accurate procedure for solving the 3-D boundary layer equation for aerospace configurations; develop an interface program to couple selected 3-D inviscid programs that span the subsonic to hypersonic Mach number range; and document and release software to the LFC community. The interface program was found to be a dependable approach for developing a user friendly procedure for generating the boundary-layer grid and transforming an inviscid solution from a relatively coarse grid to a sufficiently fine boundary-layer grid. The boundary-layer program was shown to be fourth-order accurate in the direction normal to the wall boundary and second-order accurate in planes parallel to the boundary. The fourth-order accuracy allows accurate calculations with as few as one-fifth the number of grid points required for conventional second-order schemes

    Microwave-enhanced synthesis of biodegradable multifunctional chitosan hydrogels for wastewater treatment

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    Chitosan, a derivative of chitin, is a biodegradable polymer known of its favorable properties, applicable in medicine and industry. Commonly obtained chitosan hydrogels are of various swelling capacity, and may bind only anions losing their susceptibility to biodegradation. Hydrogels are mostly obtained using toxic crosslinkers, which pollute environment due to waste generation during their synthesis. In the present article a novel, waste-free method for obtaining chitosan hydrogels under microwave irradiation, is described. Their chemical and morphological structure, swelling properties, sorption capability of a model dye and cadmium ions are described, and kinetic studies, were carried out. Biodegradability of the obtained hydrogels was investigated with the Sturm Test method. As a result, multifunctional chitosan hydrogels with both negative and positive surface charges and increased ability of anions and cations binding, were obtained. Materials were fully biodegradable, capable to absorb high amounts of water, as well as to remove various water contaminants.Web of Science111081980

    The Determinants of Survival of Spanish Consumers Fronting the BSE Crisis

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    The impact of food scares on meat consumption has been traditionally investigated by estimating food demand systems using aggregated time series. Only a few have considered micro data but none of them has tried to quantify consumers’ reaction to food scares and the speed of such reactions. In this study we apply duration analysis techniques with the aim of analysing the effect of different explanatory variables on both the risk of reducing beef consumption and the timing of this reduction. Our results suggest that the maximum hazard occurs during the few months after the occurrence of the food crisis and then the reducing consumption hazard tend to diminish. Moreover, economic factors such as prices and income could be considered as the most determinant factors of the survival of the Spanish consumers facing the BSE crisis while other socioeconomic characteristics such as the age, the gender, etc., have a small, if any, effect on the occurrence and the speed of beef consumption reduction indicating a quite homogenous reaction among Spanish consumers to BSE crisis. These results provide interesting insights about how policy makers could orientate food policies in order to recover consumption after a food scare.Food scare, BSE, duration analysis, reaction timing, Spain, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries, C41, D1,
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