9,785 research outputs found

    High Input Impedance Voltage-Mode Universal Biquadratic Filters With Three Inputs Using Three CCs and Grounding Capacitors

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    Two current conveyors (CCs) based high input impedance voltage-mode universal biquadratic filters each with three input terminals and one output terminal are presented. The first circuit is composed of three differential voltage current conveyors (DVCCs), two grounded capacitors and four resistors. The second circuit is composed of two DVCCs, one differential difference current conveyor (DDCC), two grounded capacitors and four grounded resistors. The proposed circuits can realize all the standard filter functions, namely, lowpass, bandpass, highpass, notch and allpass filters by the selections of different input voltage terminals. The proposed circuits offer the features of high input impedance, using only grounded capacitors and low active and passive sensitivities. Moreover, the x ports of the DVCCs (or DDCC) in the proposed circuits are connected directly to resistors. This design offers the feature of a direct incorporation of the parasitic resistance at the x terminal of the DVCC (DDCC), Rx, as a part of the main resistance

    Study of the Brazil and Falkland currents using their images of Nimbus 5 and oceanographic data in 1972 - 1973

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    The Western Edge of the Sub-tropical Convergence of the South-western Atlantic Ocean, called the Front, which is a thermal discontinuity between the Brazil and Falkland Currents, was studied utilizing the Temperature Humidity Infrared Radiometer (THIR) of Nimbus V in the 10.5 to 12.5 micrometers channel and historical oceanographic data. Some important results obtained are: the oceanographic Front could be detected from Nimbus THIR data; oceanographic charts showed that the transition zone where the Brazil and the Falkland Currents meet was the Front detected from satellite data; ocean current speeds calculated with THIR data were of the same order of magnitude as those calculated oceanographically; fisheries statistics for Pargo Roseo showed that the maximum catches were in September of 1973, in the period when the Front was observed most distinctly and clearly. The results showed the great potentiality of satellite data to study surface thermal structures, surface currents and oceanic fisheries

    Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry

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    Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated

    Misuse Detection in Consent-based Networks

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    Consent-based networking, which requires senders to have permission to send traffic, can protect against multiple attacks on the network. Highly dynamic networks like Mobile Ad-hoc Networks (MANETs) require destination-based consent networking, where consent needs to be given to send to a destination in any path. These networks are susceptible to multipath misuses by misbehaving nodes. In this paper, we identify the misuses in destination-based consent networking, and provide solution for detecting and recovering from the misuses. Our solution is based on our previously introduced DIPLOMA architecture. DIPLOMA is a deny-by-default distributed policy enforcement architecture that can protect the end-host services and network bandwidth. DIPLOMA uses capabilities to provide consent for sending traffic. In this paper, we identify how senders and receivers can misuse capabilities by using them in multiple paths, and provide distributed solutions for detecting those misuses. To that end, we modify the capabilities to aid in misuse detection and provide protocols for exchanging information for distributed detection. We also provide efficient algorithms for misuse detection, and protocols for providing proof of misuse. Our solutions can handle privacy issues associated with the exchange of information for misuse detection. We have implemented the misuse detection and recovery in DIPLOMA systems running on Linux operating systems, and conducted extensive experimental evaluation of the system in Orbit MANET testbed. The results show our system is effective in detecting and containing multipath misuses

    Understanding Multiple Adoption in C2C Platforms in China

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    The network effect is the general principle that the value of connecting to a network depends on the number of existing customers in the network. Usually, the network effect makes strong firms stronger and weak firms weaker. In e-commerce, however, the power of network effects can be mitigated when users adopt multiple transaction platforms (i.e., multiple adoption). Owing to multiple adoption, emerging firms have a chance to compete with or surpass strong incumbents. This empirical study showed that, because of multiple adoption, smaller players can still exist in the face of a dominant player in China’s competitive online auction platforms

    Inhibition of dengue virus replication by novel inhibitors of RNA-dependent RNA polymerase and protease activities

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    Dengue virus (DENV) is the leading mosquito-transmitted viral infection in the world. With more than 390 million new infections annually, and up to 1 million clinical cases with severe disease manifestations, there continues to be a need to develop new antiviral agents against dengue infection. In addition, there is no approved anti-DENV agents for treating DENV-infected patients. In the present study, we identified new compounds with anti-DENV replication activity by targeting viral replication enzymes – NS5, RNA-dependent RNA polymerase (RdRp) and NS3 protease, using cell-based reporter assay. Subsequently, we performed an enzyme-based assay to clarify the action of these compounds against DENV RdRp or NS3 protease activity. Moreover, these compounds exhibited anti-DENV activity in vivo in the ICR-suckling DENV-infected mouse model. Combination drug treatment exhibited a synergistic inhibition of DENV replication. These results describe novel prototypical small anti-DENV molecules for further development through compound modification and provide potential antivirals for treating DENV infection and DENV-related diseases
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