1,224 research outputs found

    Estimation of discontinuous coefficients and boundary parameters for hyperbolic systems

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    The problem of estimating discontinuous coefficients, including locations of discontinuities, that occur in second order hyperbolic systems typical of those arising in I-D surface seismic problems is discussed. In addition, the problem of identifying unknown parameters that appear in boundary conditions for the system is treated. A spline-based approximation theory is presented, together with related convergence findings and representative numerical examples

    Combined State and Parameter Estimation for a Static Model of the Maypole (Hoop-Column) Antenna Suface

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    Parameter and state estimation techniques are discussed for an elliptic system arising in a developmental model for the antenna surface of the Maypole Hoop/Column antenna. A computational algorithm based on spline approximations for the state and elastic parameters is given and numerical results obtained using this algorithm are summarized

    Varied Signature Splitting Phenomena in Odd Proton Nuclei

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    Varied signature splitting phenomena in odd proton rare earth nuclei are investigated. Signature splitting as functions of KK and jj in the angular momentum projection theory is explicitly shown and compared with those of the particle rotor model. The observed deviations from these rules are due to the band mixings. The recently measured 169^{169}Ta high spin data are taken as a typical example where fruitful information about signature effects can be extracted. Six bands, two of which have not yet been observed, were calculated and discussed in detail in this paper. The experimentally unknown band head energies are given

    Anomalous Crossing Frequency in Odd Proton Nuclei

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    A generic explanation for the recently observed anomalous crossing frequencies in odd proton rare earth nuclei is given. As an example, the proton 12[541]{1\over 2} [541] band in 175^{175}Ta is discussed in detail by using the angular momentum projection theory. It is shown that the quadrupole pairing interaction is decisive in delaying the crossing point and the changes in crossing frequency along the isotope chain are due to the different neutron shell fillings

    A Police Officer’s Tacit Knowledge Inventory (POTKI): Establishing Construct Validity and Exploring Applications

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    Research summarizes the construction of a Police Officer’s Tacit Knowledge Inventory (Inventory), a situational judgment test comprised of knowledge gained on-the-job by experienced police officers, and examines if it can play a role in the development of expertise. Correlation and regression analysis was done to establish the Inventory’s ability to predict post-Academy graduation performance. Results show that Inventory response patterns correlate with Supervisor ratings; and the Inventory responses correctly predict significant differences between novice patrol officers and experienced police officers

    Modeling Operating Speed and Deceleration on Two-Lane Rural Roads with Global Positioning System Data

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    [EN] In the road design process, speed variation along the road segment is an important issue to consider in adapting road geometry to drivers' expectations. To achieve this objective, speed criteria are used to evaluate road consistency. Being able to estimate the operating speed in the design phase can lead to safer road alignment. With this objective, several researchers have developed operating speed models. Most of these models are based on collected spot speed data. They assume constant speed on curves and, therefore, deceleration that occurs entirely on the approach tangent. According to these assumptions, spot speed data are collected at the center of the horizontal curve and at the midpoint of the preceding tangent to obtain operating speed models. This paper presents a new methodology based on the use of Global Positioning System devices that allow continuous collecting and processing of speed data. With this new methodology, not only can new and more accurate operating speed models he developed, but cited hypotheses can also be checked. Observed speed continuous profiles allow studies that previously could not be done, especially as related to deceleration and speed variations. This study calibrated new speed models, including three for horizontal curves with a radius curve and the curvature change rate of a single curve as explanatory variables, and one for tangents that incorporates the curve speed model. Tangent-curve speed variations are evaluated, with comparison of Delta(85)V and Delta V(85), analysis of the deceleration length occurring on a curve, and development of two deceleration models.The authors thank the Center for Studies and Experimentation of Public Works of the Spanish Ministry of Public Works, which partially subsidized the research. The authors also thank the Infrastructure and Transportation Department, General Directorate of Public Works, Valencian Government, Spain; the Valencian Provincial Council; and the Ministry of the Interior, General Directorate of Traffic, Spain, for their cooperation in field data gathering.PĂ©rez Zuriaga, AM.; GarcĂ­a GarcĂ­a, A.; Camacho-Torregrosa, FJ.; D'attoma, P. (2010). Modeling Operating Speed and Deceleration on Two-Lane Rural Roads with Global Positioning System Data. Transportation Research Record. 2171:11-20. doi:10.3141/2171-02S1120217

    Attraction between DNA molecules mediated by multivalent ions

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    The effective force between two parallel DNA molecules is calculated as a function of their mutual separation for different valencies of counter- and salt ions and different salt concentrations. Computer simulations of the primitive model are used and the shape of the DNA molecules is accurately modelled using different geometrical shapes. We find that multivalent ions induce a significant attraction between the DNA molecules whose strength can be tuned by the averaged valency of the ions. The physical origin of the attraction is traced back either to electrostatics or to entropic contributions. For multivalent counter- and monovalent salt ions, we find a salt-induced stabilization effect: the force is first attractive but gets repulsive for increasing salt concentration. Furthermore, we show that the multivalent-ion-induced attraction does not necessarily correlate with DNA overcharging.Comment: 51 pages and 13 figure
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