13 research outputs found

    Self-Consistent Two-Gap Description of MgBâ‚‚ Superconductor

    Get PDF
    A self-consistent two-gap γ-model is used to quantitatively describe several thermodynamic properties of MgB2 superconductor. The superconducting coupling matrix, vij, was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that γ-model provides adequate quantitative description of the two-gap superconductivity in MgB2 and may serve as a relatively simple and versatile self-consistent description of the thermodynamic quantities in multi-gap superconductors

    Unconventional nodal superconductivity in miassite Rh17_{17}S15_{15}

    Full text link
    Unconventional superconductivity has long been believed to arise from a lab-grown correlated electronic system. Here we report compelling evidence of unconventional nodal superconductivity in a mineral superconductor \rhs. We investigated the temperature-dependent London penetration depth Δλ(T)\Delta\lambda(T) and disorder evolution of the critical temperature TcT_c and upper critical field Hc2(T)H_{c2}(T) in synthetic miassite \rhs. We found a power-law behavior of Δλ(T)∼Tn\Delta\lambda(T)\sim T^n with n≈1.1n\approx 1.1 at low temperatures below 0.3Tc0.3T_c (TcT_c = 5.4 K), which is consistent with the presence of lines of the node in the superconducting gap of \rhs. The nodal character of the superconducting state in \rhs~was supported by the observed pairbreaking effect in TcT_c and Hc2(T)H_{c2}(T) in samples with the controlled disorder that was introduced by low-temperature electron irradiation. We propose a nodal sign-changing superconducting gap in the A1gA_{1g} irreducible representation, which preserves the cubic symmetry of the crystal and is in excellent agreement with the superfluid density, λ2(0)/λ2(T)\lambda^2(0)/\lambda^2(T)

    A stochastic optimization of the production speed of robots based on measured geometric and nongeometric errors

    No full text
    A statistical model is established to estimate the effects of the geometric and nongeometric errors on the quality of the operation for various operating speeds. Furthermore, a stochasitc optimization problem is formulated to obtain the optimal operating speed for a given accuracy in the robotic operations. To demonstrate this approach, the experiments on a PUMA 560 robot are used as an example. © 1992 Taylor & Francis Group, LLC

    Automated Verification Methodology of Security Events Based on Heuristic Analysis

    No full text
    We present an automated verification methodology of the security events, that is, IDS alerts, based on heuristic analysis. The proposed verification methodology aims to automatically identify real cyberattacks from the security events and filter out false positive, so that the security analyst is able to conduct security monitoring and response more effectively. For the proposed verification methodology, we used the 1,528,730,667 security events that were obtained from Science and Technology Security Center (S&T-SEC). We then extracted the core security events that were caused by the real cyberattacks. Among the core security events, we selected the top 20 types of the security events in the number of the real attacks that they raised. By analyzing the top 20 types of the security events, we discovered essential elements and optional elements for using in the automated verification of the security events. The evaluation results showed that the proposed verification methodology could contribute to the reduction (about 67%) of the meaningless security events. Furthermore, we demonstrated that the proposed verification methodology contributed to the detection of 140 true negatives that were not identified by the security analyst and the total accuracy of the proposed verification methodology was 96.1%

    Self-Consistent Two-Gap Description of MgB2 Superconductor

    Get PDF
    A self-consistent two-gap γ -model is used to quantitatively describe several thermodynamic properties of MgB 2 superconductor. The superconducting coupling matrix, νij , was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that γ -model provides adequate quantitative description of the two-gap superconductivity in MgB 2 and may serve as a relatively simple and versatile self-consistent description of the thermodynamic quantities in multi-gap superconductors.</p

    Self-Consistent Two-Gap Description of MgB2 Superconductor

    No full text
    A self-consistent two-gap &gamma; -model is used to quantitatively describe several thermodynamic properties of MgB 2 superconductor. The superconducting coupling matrix, &nu; i j , was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that &gamma; -model provides adequate quantitative description of the two-gap superconductivity in MgB 2 and may serve as a relatively simple and versatile self-consistent description of the thermodynamic quantities in multi-gap superconductors

    UPLC-QTOF/MS-Based Metabolomics Applied for the Quality Evaluation of Four Processed Panax ginseng Products

    No full text
    In the food industry and herbal markets, it is critical to control the quality of processed Panax ginseng products. In this study, ultra-performance liquid chromatography coupled to quadrupole time of flight mass spectrometry (UPLC-QTOF/MS)-based metabolomics was applied for the quality evaluation of white ginseng (WG), tae-geuk ginseng (TG), red ginseng (RG), and black ginseng (BG). Diverse metabolites including ginsenosides were profiled by UPLC-QTOF/MS, and the datasets of WG, TG, RG, and BG were then subjected to multivariate analyses. In principal component analysis (PCA), four processed ginseng products were well-differentiated, and several ginsenosides were identified as major components of each product. S-plot also characterized the metabolic changes between two processed ginseng products, and the major ginsenosides of each product were found as follows: WG (M-Rb1, M-Rb2, M-Rc, Re, Rg1), TG (Rb2, Rc, Rd, Re, Rg1), RG (Rb1, Rb2, Rc, Rd, Re, Rg1), and BG (Rd, Rk1, Rg5, Rg3). Furthermore, the quantitative contents of ginsenosides were evaluated from the four processed ginseng products. Finally, it was indicated that the proposed metabolomics approach was useful for the quality evaluation and control of processed ginseng products
    corecore