Generation of noise sequences with desired non-Gaussian distribution and covariance

It is necessary to generate a noise sequence in the simulation of the communication system and signal processing. In the design of some practical system such as radar system, we Must generate a stationary noise sequence with a specified non-Gaussian probability density function and a desired power spectrum to test the performance of the system. For this purpose, this paper presents a method by which such a clutter sequence can be generated. The examples are also demonstrated to show the effectiveness of the proposed method.published_or_final_versio

Multi-resolution decomposition applied to crackle detection

Crackles, heard over the lungs in a variety of diseases, are one of the most important physical signs in clinical medicine. They have an explosive pattern in the time domain, with a rapid onset and short duration. The timing, repeatability and shape of crackles are important parameters for diagnosis. Therefore, automatic detection of crackles and their classification as fine and coarse crackles have important clinical value. Since the multi-resolution decomposition technique can give high resolution in both time and frequency, it can be exploited to detect crackles and to classify them according to the information in each scale. In this paper, we present a new method for crackle detection based on the continuous wavelet transform. The theory, methods and experimental results are given in detail in this paper.published_or_final_versio

The investigation of time-varying synchrony of EEG during sentence learning using wavelet analysis

The synchrony analysis has been used as a tool for the purpose of investigating how the cognitive processes take place between different brain regions when the specified learning task is going on. We propose a novel method based on the time-frequency representation for quantifying synchronization between two channel EEG with both temporal and spectral resolution. The presented method employed the wavelet transform for cross coherent spectral analysis of the EEG signals recorded during sentences recognizing and learning. The wavelet-coherent magnitude spectra provide the information indicating the degree of coherence and the cross-wavelet phase relation serves to indicate the direction of information flow between two EEG channels on different cortical regions. Real EEG recordings are collected based on a cognitive target. It is observed from both the magnitude spectra and phase of the wavelet coherence that there are obvious differences between the identification of both Chinese and English sentences. These are helpful for the research on the English study for Chinese students.published_or_final_versio

Control and operation of a new 8/6-pole doubly salient permanent-magnet motor drive

This paper proposes a new 8/6-pole doubly salient permanent-magnet (DSPM) motor drive, which offers the advantages of higher power density, higher efficiency, and wider speed range. The corresponding control and operation of the motor drive are presented. A variable proportional-integral (PI) controller combined with bang-bang control for the DSPM motor drive is developed. Two operation modes, namely, four-phase and two-phase operation modes, are proposed for the 8/6-pole DSPM motor drive. The drive system is implemented and tested. The results show that the developed control scheme can operate the DSPM motor properly, and the DSPM motor drive offers high efficiency over wide power range and good dynamic performance. Furthermore, the two-phase operation mode of the 8/6-pole DSPM motor offers the possibility of eliminating the torque ripple of the motor drive.published_or_final_versio

Filling the missing gaps on research in Chinese adolescents (Editorial)

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Metal-Poor Stars Observed with the Magellan Telescope. III. New Extremely and Ultra Metal-Poor Stars from SDSS/SEGUE and Insights on the Formation of Ultra Metal-Poor Stars

We report the discovery of one extremely metal-poor (EMP; [Fe/H]<-3) and one ultra metal-poor (UMP; [Fe/H]<-4) star selected from the SDSS/SEGUE survey. These stars were identified as EMP candidates based on their medium-resolution (R~2,000) spectra, and were followed-up with high-resolution (R~35,000) spectroscopy with the Magellan-Clay Telescope. Their derived chemical abundances exhibit good agreement with those of stars with similar metallicities. We also provide new insights on the formation of the UMP stars, based on comparison with a new set of theoretical models of supernovae nucleosynthesis. The models were matched with 20 UMP stars found in the literature, together with one of the program stars (SDSS J1204+1201), with [Fe/H]=-4.34. From fitting their abundances, we find that the supernovae progenitors, for stars where carbon and nitrogen are measured, had masses ranging from 20.5 M_sun to 28 M_sun and explosion energies from 0.3 to 0.9x10^51 erg. These results are highly sensitive to the carbon and nitrogen abundance determinations, which is one of the main drivers for future high-resolution follow-up of UMP candidates. In addition, we are able to reproduce the different CNO abundance patterns found in UMP stars with a single progenitor type, by varying its mass and explosion energy.Comment: 15 pages, 12 figures; accepted for publication in Ap

Crackle detection and classification based on matched waveletanalysis

Crackles have an explosive pattern in the time domain, with a rapid onset and a short duration. The timing, repeatability and shape of crackles are important parameters for diagnosis. Therefore, automatic detection of crackles and their classification have important clinical value. Since crackles have a general characteristic shape, it is obvious that wavelet analysis can be exploited to detect crackles and to classify them. In this paper, we present a new method for crackle detection which is based on a `matched' wavelet transform. We first model crackles as a mathematical function. Then we design a matched wavelet based on this model. Applying a soft threshold to the results of the continuous wavelet transform to suppress noise further, the optimal scale can be obtained. Crackles can be detected based on the envelope of the signal at an optimal scale, and can be classified based on the energy distribution with scale. Theory, methods and experimental results are given in detail in this paper.published_or_final_versio

A practical guide to density matrix embedding theory in quantum chemistry

Density matrix embedding theory (DMET) provides a theoretical framework to treat finite fragments in the presence of a surrounding molecular or bulk environment, even when there is significant correlation or entanglement between the two. In this work, we give a practically oriented and explicit description of the numerical and theoretical formulation of DMET. We also describe in detail how to perform self-consistent DMET optimizations. We explore different embedding strategies with and without a self-consistency condition in hydrogen rings, beryllium rings, and a sample S$_{\text{N}}$2 reaction. The source code for the calculations in this work can be obtained from \url{https://github.com/sebwouters/qc-dmet}.Comment: 41 pages, 10 figure

Enrichment of committed, chondroitin sulfate-expressing human nucleus pulposus cells over progenitors under alginate encapsulation

INTRODUCTION: Accumulating evidence has suggested a heterogeneous NP cell population in adult human IVDs [1, 2], possibly a result of cells being at different differentiation states. The heterogeneous cell populations include the primitive NP cells (also regarded as notochordal NP cells) [1, 2], mature NP cells, and local disc progenitors [1] with various capacities in proteoglycan production other than chondrocytic NP cells. Cross-linked alginate hydrogel provides a favorable three-dimensional microenvironment for promotion of chondrogenic phenotype [3] with enhanced biosynthesis of proteoglycans (PGs) and collagen II. It has been widely used as a bioactive scaffold for engineering of ...postprin