263,332 research outputs found

    N-fold Parasupersymmetry

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    We find a new type of non-linear supersymmetries, called N-fold parasupersymmetry, which is a generalization of both N-fold supersymmetry and parasupersymmetry. We provide a general formulation of this new symmetry and then construct a second-order N-fold parasupersymmetric quantum system where all the components of N-fold parasupercharges are given by type A N-fold supercharges. We show that this system exactly reduces to the Rubakov-Spiridonov model when N=1 and admits a generalized type C 2N-fold superalgebra. We conjecture the existence of other `N-fold generalizations' such as N-fold fractional supersymmetry, N-fold orthosupersymmetry, and so on.Comment: 10 pages, no figures; Intro. expande

    Properties and Curie Temperature (130 K) of Heavily Mn-doped Quaternary Alloy Ferromagnetic Semiconductor (InGaMn)As Grown on InP

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    We have studied magnetic properties of heavily Mn-doped [(In0.44Ga0.56)0.79Mn0.21]As thin films grown by low-temperature molecular-beam epitaxy (LT-MBE) on InP substrates. The (InGaMn)As with high Mn content (21%) was obtained by decreasing the growth temperature to 190 degC. When the thickness of the [(In0.44Ga0.56)0.79Mn0.21]As layer is equal or thinner than 10 nm, the reflection high-energy electron diffraction (RHEED) pattern and transmission electron microscopy (TEM) show no MnAs clustering, indicating that a homogeneous single crystal with good quality was grown. In the magnetic circular dicroism (MCD) measurement, large MCD intensity and high Curie temperature of 130 K were observed.Comment: 3 pages, 5 figure

    Effects of disorder on conductance through small interacting systems

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    We study the effects of disorders on the transport through small interacting systems based on a two-dimensional Hubbard cluster of finite size connected to two noninteracting leads. This system can be regarded as a model for the superlattice of quantum dots or atomic network of the nanometer size. We calculate the conductance at T=0 using the order U2U^2 self-energy in an electron-hole symmetric case. The results show that the conductance is ensitive to the randomness when the resonance states are situated near the Fermi energy.Comment: 2 pages, 3 figures, to be published in Physica E, proceedings Low Temperature Physics 23 (Hirosima, Japan

    Strong consistency of the maximum likelihood estimator for finite mixtures of location-scale distributions when penalty is imposed on the ratios of the scale parameters

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    In finite mixtures of location-scale distributions, if there is no constraint or penalty on the parameters, then the maximum likelihood estimator does not exist because the likelihood is unbounded. To avoid this problem, we consider a penalized likelihood, where the penalty is a function of the minimum of the ratios of the scale parameters and the sample size. It is shown that the penalized maximum likelihood estimator is strongly consistent. We also analyze the consistency of a penalized maximum likelihood estimator where the penalty is imposed on the scale parameters themselves.Comment: 29 pages, 2 figure

    Practical Model Construction and Stable Control of an Unmanned Aerial Vehicle With a Parafoil-Type Wing

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    This correspondence paper presents a framework for practical model construction and stable altitude control of an unmanned aerial vehicle with a parafoil-type wing (UAV-PW). To design a stable controller, we first construct a dynamical longitudinal model of the UAV-PW. Since there exist no aerodynamics data of the parafoil shape in our UAV-PW, aerodynamics coefficients balanced at the trimmed equilibrium are employed. The model accuracy is investigated by comparing the model outputs with the real test flight experimental data. Next, stable controller design conditions for the UAV-PW model with uncertainties are derived in terms of linear matrix inequalities (LMIs). By solving the LMI conditions, we design a stable controller that asymptotically stabilizes the UAV-PW model with the uncertainties on a considered operation domain. The experimental results demonstrate the viability of the model construction and the stable altitude control

    Transport through a single Anderson impurity coupled to one normal and two superconducting leads

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    We study the interplay between the Kondo and Andreev-Josephson effects in a quantum dot coupled to one normal and two superconducting (SC) leads. In the large gap limit, the low-energy states of this system can be described exactly by a local Fermi liquid for the interacting Bogoliubov particles. The phase shift and the renormalized parameters for the Bogoliubov particles vary depending on the Josephson phase between the two SC leads. We explore the precise features of a crossover that occurs between the Kondo singlet and local Cooper-pairing states as the Josephson phase varies, using the numerical renormalization group approach.Comment: 4 pages, 4 figures, contribution to SCES 201

    Homogeneous SPC/E water nucleation in large molecular dynamics simulations

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    We perform direct large molecular dynamics simulations of homogeneous SPC/E water nucleation, using up to 4106\sim 4\cdot 10^6 molecules. Our large system sizes allow us to measure extremely low and accurate nucleation rates, down to 1019cm3s1\sim 10^{19}\,\textrm{cm}^{-3}\textrm{s}^{-1}, helping close the gap between experimentally measured rates 1017cm3s1\sim 10^{17}\,\textrm{cm}^{-3}\textrm{s}^{-1}. We are also able to precisely measure size distributions, sticking efficiencies, cluster temperatures, and cluster internal densities. We introduce a new functional form to implement the Yasuoka-Matsumoto nucleation rate measurement technique (threshold method). Comparison to nucleation models shows that classical nucleation theory over-estimates nucleation rates by a few orders of magnitude. The semi-phenomenological nucleation model does better, under-predicting rates by at worst, a factor of 24. Unlike what has been observed in Lennard-Jones simulations, post-critical clusters have temperatures consistent with the run average temperature. Also, we observe that post-critical clusters have densities very slightly higher, 5%\sim 5\%, than bulk liquid. We re-calibrate a Hale-type JJ vs. SS scaling relation using both experimental and simulation data, finding remarkable consistency in over 3030 orders of magnitude in the nucleation rate range, and 180180\,K in the temperature range.Comment: Accepted for publication in the Journal of Chemical Physic

    A Method to Extract the Structural Strata and Elements of Landscape Using GIS

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    Analyzing the landscape with using large three-dimensional database is well noted as the new method. In applying the method, the measure to divide the database into several densities of data to adjust many places and to analyze in mainframe computer is in need. The purpose of this study is to clarify the method of dividing spaces into structural layer, which can be measured in its quantity._ The theoretical method to extract the landscape elements by the distance from the viewpoint has been recognized by the previous studies, which based on the human phenomenon philosophy. However, the quantities of distance, which defines the space as a whole environment around viewpoint is not yet applicable for practical design. Because, the quantities have not been clearly found to apply to the real space since, feelings of distance varies by personal image. The cause of differences are due to some factors such as physical factors including the topography, the vegetation, and the building surroundings. Furthermore, there are other factors for example, psychological and social._ In this study, the physically caused distance definition is to be cleared through the method to extract the structural strata and the elements of landscape._ As an initial analysis, the angle of gaze from viewpoint, based on human engineering, the heights of the layers were examined and clearly found. The relationship between the eyesight and the angle of gaze are analyzed. Secondly, the continuity of figure from viewpoint are measured. It applied the fifty meters mesh digital map, the topographic vector data, the aerial photograph, and the building form vector data, to the Geographic Information System; the SIS and the ArcGIS. It proved that three scale of view; the close, the distance, and the background divides the real landscape. With this result, the method to extract the structural strata are found._ Preliminary, the methodsÕ application was tried to real spaces for further analysis. The results encouraged the analysis of physical quantity related with the human image including the time-space, and the relationship between the view and the other sense, which are under processes._
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