605 research outputs found

    Simulated Design of Water Level Control System

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    In this paper, the modelling and simulation of a water tank level controller using fuzzy logic approach has been achieved. This project is aimed at the design and simulation of a fuzzy logic based controller that will provide a stabilized output response. In order to successfully achieve this project, emphasis was made on two areas; the foundational knowledge of fuzzy logic and the fuzzy inference system, and the definition of the tank system model and its parameters.  The design was implemented using Fuzzy Logic Toolbox package and SIMULINK environment which can be found in MATLAB software. For the purpose of analysis, the controller was simulated using a variety of rules in order to test the effect of the rules on the fuzzy logic controller. Results will show that fuzzy logic can realize faster results, superior features, and better end product performance with respect to overshoots, oscillations and response time. Keywords: Fuzzy logic, Control System Design, Matlab, Simulin

    Creation and pinning of vortex-antivortex pairs

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    Computer modeling is reported about the creation and pinning of a magnetic vortex-antivortex (V-AV) pair in a superconducting thin film, due to the magnetic field of a vertical magnetic dipole above the film, and two antidot pins inside the film. For film thickness =0.1ξ= 0.1\xi, κ=2\kappa = 2, and no pins, we find the film carries two V-AV pairs at steady state in the imposed flux range 2.10Φ0<Φ+<3.0Φ02.10\Phi_0 < \Phi^+ < 3.0\Phi_0, and no pairs below. With two antidot pins suitably introduced into the film, a single V-AV pair can be stable in the film for Φ+1.3Φ0\Phi^+ \ge 1.3\Phi_0. At pin separation 17ξ\ge 17\xi, we find the V-AV pair remains pinned after the dipole field is removed, and, so can represent a 1 for a nonvolatile memory.Comment: 8 pages, 6 figure

    Design and fabrication of a long-life Stirling cycle cooler for space application. Phase 3: Prototype model

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    A second-generation, Stirling-cycle cryocooler (cryogenic refrigerator) for space applications, with a cooling capacity of 5 watts at 65 K, was recently completed. The refrigerator, called the Prototype Model, was designed with a goal of 5 year life with no degradation in cooling performance. The free displacer and free piston of the refrigerator are driven directly by moving-magnet linear motors with the moving elements supported by active magnetic bearings. The use of clearance seals and the absence of outgassing material in the working volume of the refrigerator enable long-life operation with no deterioration in performance. Fiber-optic sensors detect the radial position of the shafts and provide a control signal for the magnetic bearings. The frequency, phase, stroke, and offset of the compressor and expander are controlled by signals from precision linear position sensors (LVDTs). The vibration generated by the compressor and expander is cancelled by an active counter balance which also uses a moving-magnet linear motor and magnetic bearings. The driving signal for the counter balance is derived from the compressor and expander position sensors which have wide bandwidth for suppression of harmonic vibrations. The efficiency of the three active members, which operate in a resonant mode, is enhanced by a magnetic spring in the expander and by gas springs in the compressor and counterbalance. The cooling was achieved with a total motor input power of 139 watts. The magnetic-bearing stiffness was significantly increased from the first-generation cooler to accommodate shuttle launch vibrations

    Minimal window duration for accurate HRV recording in athletes

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    Heart rate variability (HRV) is non-invasive and commonly used for monitoring responses to training loads, fitness, or overreaching in athletes. Yet, the recording duration for aseries of RR-intervals varies from 1 to 15 min in the literature. The aim of the present work was to assess the minimum record duration to obtain reliableHRV results. RR-intervalsfrom 159 orthostatic tests (7 min supine, SU, followed by 6 min standing, ST) were analyzed. Reference windows were 4 min in SU (min 3–7) and 4 min in ST (min 9–13).Those windows were subsequently divided and the analyses were repeated on eight different fractioned windows: the first min (0–1), the second min (1–2), the third min (2–3),the fourth min (3–4), the first 2 min (0–2), the last 2 min (2–4), the first 3 min (0–3), and thelast 3 min (1–4). Correlation and Bland & Altman statistical analyses were systematically performed. The analysis window could be shortened to 0–2 instead of 0–4 for RMSSD only, whereas the 4-min window was necessary for LF and total power. Since there is a need for 1 min of baseline to obtain a steady signal prior the analysis window, we conclude that studies relying on RMSSD may shorten the windows to 3 min (=1+2)in SU or seated position only and to 6 min (=1+2 min SU plus 1+2 min ST) if there is an orthostatic test. Studies relying on time- and frequency-domain parameters need a minimum of 5 min (=1+4) min SU or seated position only but require 10 min (=1+4 minSU plus 1+4 min ST) for the orthostatic tes

    Non Insulin Dependent Diabetes in Sand Rat (Psammomys obesus) and Production of Collagen in Cultured Aortic Smooth Muscle Cells. Influence of Insulin

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    In this report, we have shown that the standard laboratory diet administered to Psammomys obesus (sand rat) from Beni Abbes in Algeria, induced a non-insulin dependant diabetes, characterised by increase of body weight (p<0.001) as well as hyperinsulinemia, hyperglycemia and hypercholesterolemia. In cultured aortic smooth muscle cells (SMC) of sand rats, type I and type III collagen biosynthesis and insulin effects, at low dose, on these parameters were investigated. In all experimental conditions of cultured SMC study, The α chains of type I collagen were analysed by immunoblotting in media and cells

    A content-linking-context model for “notice-and-takedown” procedures

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    The US Digital Millennium Copyright Act (DMCA) of 1998 adopted a notice-and-take-down procedure to help tackle alleged online infringements through online service providers’ actions. The European Directive 2000/31/EC (e-Commerce Directive) introduced similar liability exemptions, but did not specify any take-down procedure. Many intermediary (host, and online search engine) service providers even in Europe have followed this notice-and-take-down procedure to enable copyright owners to issue notices to take down allegedly infringing Web resources. However, the accuracy of take-down is not known, and notice receivers do not reveal clear information about how they check the legitimacy of these requests, about whether and how they check the lawfulness of allegedly infringing content, or what criteria they use for these actions. In this paper, we use Google’s Transparency Report as the benchmark to investigate the information content of take-down notices and the accuracy of the resulting take-downs of allegedly infringing Web resources. The analysis of copyright infringement is limited to the five scenarios most frequently encountered in our study of Web resources. Based on our investigation, we propose a Content-Linking-Context (CLC) model of the criteria to be considered by intermediary service providers to achieve more accurate take-down

    A way to increase the bit ratein ionospheric radio links

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    The aim of this paper is to present a high data rate transmission system through the ionospheric channel in the HF-band (3-30 MHz). The applications expected in this study are image transmitting and real-time videoconferencing. Very high rates are required compared to the standard modems. Therefore, an array processing is performed with a set of antennas whose spatial response differs from one another arranged in a circular array or in a collocated sensor. Synchronization (Zero Crossing Detector) and source separation (LMS algorithm) resort to classical well-tested techniques involving training sequences. Experimental results are presented for both antenna configurations. These techniques improve data rate, reaching 20 kbits/s within the 6 kHz bandwidth (QAM 64) without coding or interleaving

    High-resolution energy-dispersive diffraction using synchrotron radiation

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