Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.</p

Phase identification in distribution systems by data mining methods

Data mining is one of the statistical means that extracts useful information from an extremely large set of raw data. Therefore, data mining methods are under vigorous development and are commonly used in artificial intelligence fields such as image processing and robot industry. There has also been recently applications of data mining in electric power industry, such as classification, clustering and forecasting. In this research work, clustering techniques are adopted to identify the phase connectivity in power systems. Supported by smart meter data obtained from end-users on the low-voltage (LV) feeder, phase identification is properly discussed in this paper. Firstly, the LV network model is modeled using simulation tool OpenDSS. Secondly, the phase identification algorithm of the LV network is developed in Matlab by using K-means clustering as well as the Gaussian Mixture Model (GMM) clustering. Finally, the IEEE European Low Voltage Test Feeder is used to verify the proposed method. Results: indicate that these two methods enable phase identification to realize its goals, which is to precisely address the active loads as well as the correlated phase of corresponding load

Temperature versus doping phase diagrams for Ba(Fe1-xTMx)(2)As-2(TM=Ni,Cu,Cu/Co) single crystals

Microscopic, structural, transport, and thermodynamic measurements of single crystalline Ba(Fe1-xTMx)(2)As-2 (TM=Ni and Cu) series, as well as two mixed TM=Cu/Co series, are reported. In addition, high-magnetic field, anisotropic H-c2(T) data were measured up to 33 T for the optimally Ni-doped BaFe2As2 sample. All the transport and thermodynamic measurements indicate that the structural and magnetic phase transitions at 134 K in pure BaFe2As2 are monotonically suppressed and increasingly separated in a similar manner by these dopants. In the Ba(Fe1-xNix)(2)As-2 (x <= 0.072), superconductivity, with T-c up to 19 K, is stabilized for 0.024 <= x <= 0.072. In the Ba(Fe1-xCux)(2)As-2 (x <= 0.356) series, although the structural and magnetic transitions are suppressed, there is only a very limited region of superconductivity: a sharp drop of the resistivity to zero near 2.1 K is found only for the x=0.044 samples. In the Ba(Fe1-x-yCoxCuy)(2)As-2 series, superconductivity, with T-c values up to 12 K (x similar to 0.022 series) and 20 K (x similar to 0.047 series), is stabilized. Quantitative analysis of the detailed temperature-dopant concentration (T-x) and temperature-extra electrons (T-e) phase diagrams of these series shows that there exists a limited range of the number of extra electrons added, inside which the superconductivity can be stabilized if the structural and magnetic phase transitions are suppressed enough. Moreover, comparison with pressure-temperature phase diagram data, for samples spanning the whole doping range, further re-enforces the conclusion that suppression of the structural/magnetic phase transition temperature enhances T-c on the underdoped side, but for the overdoped side T-max(C) is determined by e. Therefore, by choosing the combination of dopants that are used, we can adjust the relative positions of the upper phase lines (structural and magnetic phase transitions) and the superconducting dome to control the occurrence and disappearance of the superconductivity in transition metal, electron-doped BaFe2As2.This article is published as Ni, N., A. Thaler, J. Q. Yan, A. Kracher, E. Colombier, S. L. Bud’Ko, P. C. Canfield, and S. T. Hannahs. "Temperature versus doping phase diagrams for Ba (Fe 1− x TM x) 2 As 2 (TM= Ni, Cu, Cu/Co) single crystals." Physical Review B 82, no. 2 (2010): 024519. DOI: 10.1103/PhysRevB.82.024519. Copyright 2010 American Physical Society. Posted with permission