Jointly Sparse Support Recovery via Deep Auto-encoder with Applications in MIMO-based Grant-Free Random Access for mMTC

In this paper, a data-driven approach is proposed to jointly design the common sensing (measurement) matrix and jointly support recovery method for complex signals, using a standard deep auto-encoder for real numbers. The auto-encoder in the proposed approach includes an encoder that mimics the noisy linear measurement process for jointly sparse signals with a common sensing matrix, and a decoder that approximately performs jointly sparse support recovery based on the empirical covariance matrix of noisy linear measurements. The proposed approach can effectively utilize the feature of common support and properties of sparsity patterns to achieve high recovery accuracy, and has significantly shorter computation time than existing methods. We also study an application example, i.e., device activity detection in Multiple-Input Multiple-Output (MIMO)-based grant-free random access for massive machine type communications (mMTC). The numerical results show that the proposed approach can provide pilot sequences and device activity detection with better detection accuracy and substantially shorter computation time than well-known recovery methods.Comment: 5 pages, 8 figures, to be publised in IEEE SPAWC 2020. arXiv admin note: text overlap with arXiv:2002.0262

A modified inverse vector hysteresis model for nonoriented electrical steels considering anisotropy for FEA

This paper presents a modified Mayergoyz-based vector hysteresis model to describe the anisotropic material behavior of nonoriented (NO) steels over a wide range of rotational excitations. The proposed model adopts a new representation of a vector Everett function, which is actually an elliptical interpolation motivated by the real anisotropic behavior of NO steel, to deal with the uniaxial anisotropy characteristic, which is especially pronounced for low induction levels. The biaxial anisotropy occurring at high densities is described by a nonlinear coefficient, which is actually a function of magnitude of magnetic flux density. A systematic identification algorithm is given in detail. The validity of this model is verified through comparison with experimental data under both alternating and rotational excitations. The 2-D finite element analysis (FEA) of incorporating this model into TEAM problem 32 simulation is also illustrated

Measurement and analysis of the non-symmetry of transverse magnetisation and resulting loss in grain-oriented steel using a modified RSST

A modified rotational single-sheet tester, in which a circular sample can be rotated to be magnetised along arbitrary directions, was used to study the transverse magnetisation and associated losses in grain-oriented electrical steel (GOES). Longitudinal and transverse components of flux density B and magnetic field H in a sample of commercial GOES were measured under alternating excitation at angles from −90° to +90° to the rolling direction (RD) at peak flux densities up to 1.5 T over a magnetising frequency range of 20–400 Hz. The loss due to the transverse components of B and H, referred to as the transverse loss, was evaluated. At 1.5 T, 20 Hz, the transverse loss was less than 0.1 mW/kg when magnetised along either the RD or the transverse direction but it rose to around 5 mW/kg when magnetised at 30° to the RD. It was found to be magnetising direction, frequency and flux density dependent. The transverse loss was a simple function of the angle of magnetisation with respect to the RD but it differed when magnetised along directions on either side of to the RD dependent on the grain structure in the measurement region. The basic phenomenon is explained with the aid of simple magnetic domain and magnetisation models. The difficulty of quantifying its absolute effect in GOES and non-oriented electrical steel is discussed. It appears that transverse magnetisation in GOES is not normally large enough to have any practical effect on measurements obtained using IEC Standard loss testers or on the prediction of electrical machine core losses. A preliminary series of tests showed that transverse loss also occurs in non-oriented electrical steel but it is difficult to quantify

Blood cells and hematological parameters of the mountain dragon, Diploderma micangshanensis (Squamata: Lacertilia: Agamidae)

Hematological characteristics reflect the health status of animals and their physiological adaptation to the environment. However, few studies focused on the species of Diploderma. In this study, the blood cells and the hematological parameters of Diploderma micangshanensis, a species endemic to China, were examined based on 48 healthy adult (32 males and 16 females). The blood cells and hematological parameters of D. micangshanensis were similar to those of other lizard species. Although the values of erythrocyte morphometric characters and hematological parameters varied between males and females, the differences were only significant in the case of the hematocrit and erythrocyte size, which may allow for higher oxygen availability in males. Hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscle volume were strongly affected by the snout-vent length and/or body mass, which reflect the physiological adaptation to the oxygen requirement of different individuals. This is the first report of hematological data from a species of Diploderma, and the results will provide data for research on the adaptive evolution and health assessment in this species and other congeners

Core loss calculation for magnetic materials employed in SMPS under rectangular voltage excitations

Magnetic materials are widely used in switching-mode power supplies (SMPS) and magnetic components in SMPS usually work under two typical rectangular excitations (with or without the period of zero voltage). Extensive experimental results have shown that there is quite a difference of core loss between sinusoidal excitations and rectangular excitations, which means the traditional core loss calculation methods are no longer applicable. In this paper, two formulas for core loss calculation under the above rectangular excitations are derived based on the Improved Generalized Steinmetz Equation (IGSE). Core loss of different magnetic materials, under both sinusoidal excitations and rectangular excitations with different frequencies and duty cycles, are measured. Experimental results show that the formulas are accurate enough and very useful to predict the core loss

An Energy-Based Anisotropic Vector Hysteresis Model for Rotational Electromagnetic Core Loss

In this article, a model that describes the anisotropic behavior and core loss of electrical steel sheets over a wide range of rotational excitation is developed. Based on the definition of the effective field, the macroscopic anisotropy field is deduced from a weighted average of the magnetocrystalline energy of a single crystal. An anisotropic vector hysteresis model is then proposed by applying the effective field to the energy-based model. Experimental measurements are used to fit and validate the model. Either alternating or rotational measurements with a maximum magnetic flux density 1.55 T under 10 Hz are employed to fit the model parameters and the remaining set of measurements is used for validating the model accuracy. The results show that the model can naturally account for the drop in the rotational losses at high flux densities regardless of whether it is identified from alternating or rotational measurement data. The generality of the model is demonstrated through continuous angle results and modeling of another material.Peer reviewe