A Sparse Representation Speech Denoising Method Based on Adapted Stopping Residue Error

A sparse representation speech denoising method based on adapted stopping residue error was presented in this paper. Firstly, the cross-correlation between the clean speech spectrum and the noise spectrum was analyzed, and an estimation method was proposed. In the denoising method, an over-complete dictionary of the clean speech power spectrum was learned with the K-singular value decomposition (K-SVD) algorithm. In the sparse representation stage, the stopping residue error was adaptively achieved according to the estimated cross-correlation and the adjusted noise spectrum, and the orthogonal matching pursuit (OMP) approach was applied to reconstruct the clean speech spectrum from the noisy speech. Finally, the clean speech was re-synthesised via the inverse Fourier transform with the reconstructed speech spectrum and the noisy speech phase. The experiment results show that the proposed method outperforms the conventional methods in terms of subjective and objective measure

Molecular Mechanism of Z α1-Antitrypsin Deficiency.

The Z mutation (E342K) of α1-antitrypsin (α1-AT), carried by 4% of Northern Europeans, predisposes to early onset of emphysema due to decreased functional α1-AT in the lung and to liver cirrhosis due to accumulation of polymers in hepatocytes. However, it remains unclear why the Z mutation causes intracellular polymerization of nascent Z α1-AT and why 15% of the expressed Z α1-AT is secreted into circulation as functional, but polymerogenic, monomers. Here, we solve the crystal structure of the Z-monomer and have engineered replacements to assess the conformational role of residue Glu-342 in α1-AT. The results reveal that Z α1-AT has a labile strand 5 of the central β-sheet A (s5A) with a consequent equilibrium between a native inhibitory conformation, as in its crystal structure here, and an aberrant conformation with s5A only partially incorporated into the central β-sheet. This aberrant conformation, induced by the loss of interactions from the Glu-342 side chain, explains why Z α1-AT is prone to polymerization and readily binds to a 6-mer peptide, and it supports that annealing of s5A into the central β-sheet is a crucial step in the serpins' metastable conformational formation. The demonstration that the aberrant conformation can be rectified through stabilization of the labile s5A by binding of a small molecule opens a potential therapeutic approach for Z α1-AT deficiency

Structural insights into molecular mechanism for N6-adenosine methylation by MT-A70 family methyltransferase METTL4

METTL4 belongs to a subclade of MT-A70 family members of methyltransferase (MTase) proteins shown to mediate N6-adenosine methylation for both RNA and DNA in diverse eukaryotes. Here, we report that Arabidopsis METTL4 functions as U2 snRNA MTase for N6−2’-O-dimethyladenosine (m6Am) in vivo that regulates flowering time, and specifically catalyzes N6-methylation of 2’-O-methyladenosine (Am) within a single-stranded RNA in vitro. The apo structures of full-length Arabidopsis METTL4 bound to S-adenosyl-L-methionine (SAM) and the complex structure with an Am-containing RNA substrate, combined with mutagenesis and in vitro enzymatic assays, uncover a preformed L-shaped, positively-charged cavity surrounded by four loops for substrate binding and a catalytic center composed of conserved residues for specific Am nucleotide recognition and N6-methylation activity. Structural comparison of METTL4 with the mRNA m6A enzyme METTL3/METTL14 heterodimer and modeling analysis suggest a catalytic mechanism for N6-adenosine methylation by METTL4, which may be shared among MT-A70 family members

Research on Prediction of Wear Amount in the Gear Transmission Process Under Complex Working Conditions

Wear is the main failure form in the gear transmission process. The increased wear will increase the non-linear backlash of the gear teeth, reduce the transmission accuracy and increase the impact force of the tooth surface, which will lead to aggravated vibration of the gear transmission system, and impose great impact on the gear transmission performance and the stable operation of the equipment. In order to solve the above problems, a method for predicting the wear amount in the gear transmission process under complex working conditions is proposed. The gear wear state is identified and determined based on the formal wear index. Through in-depth analysis of the gear wear mechanism, a typical gear wear process curve is drawn based on this, the gear transmission friction torque value is calculated, and a mathematical model of the gear wear amount is built; then the known gear state values are input into the construction model, the predicted gear wear amount is obtained, and the prediction of gear wear amount is realized. The experimental results show that under three complex working conditions, the prediction simulation data proposed in this study is closer to the actual parameters, which fully verifies that the prediction accuracy of the wear amount is higher

Effect of Inlet Flow-Guide on Hydraulic Loss of Seawater MHD Propeller with Helical Channel

Abstract Inlet flow-guide is very important to the hydraulic loss of the whole channel of marine MHD thruster with helical channel. In this paper, variable helix is used as the line-type of flow-guide blade, and helical loop number (N), blade number (n) and blade height (H) (helix height) are established as the main geometric parameters. L 16 (43) orthogonal table was used to design the inlet flow-guide, which contains three factors with four levels of N, n and H. The whole flow filed of helical channel with inlet flow-guide was numerical simulated with Fluent. The results show that the hydraulic loss of the helical channel can be greatly reduced by the inlet flow-guide; The results of orthogonal experimental show that the hydraulic loss of the helical channel is sensitive to the line-type of the guide vane, and the total hydraulic loss increases with the increase of n, increases first and then decreases with the increase of N, and decreases first and then increases with the increase of H.</jats:p

Carbon Neutrality Assessment and Driving Factor Analysis of China&rsquo;s Offshore Fishing Industry

The marine fishing industry has a huge carbon sink potential and is also an important source of carbon emissions. The low-carbon development of the marine fishing industry is particularly important. Based on the perspective of carbon neutrality, this study analyzed the trend of net carbon emissions, carbon emissions and carbon sinks in the offshore fishing industry in China and 11 coastal provinces from 2010 to 2019 and decomposed the driving factors of the net carbon emissions of the offshore fishing industry with the LMDI decomposition method. The results show the following: (1) China&rsquo;s offshore fishing industry is in a partially carbon-neutral state. Overall, the net carbon emissions have decreased, and the carbon neutrality capacity has improved. However, the net carbon emissions have increased since 2016. From 2010 to 2019, both the carbon emissions and carbon sinks of China&rsquo;s offshore fishing industry declined. Carbon emissions fluctuated at first and then declined rapidly, while carbon sinks rose slowly and then showed a significant downward trend. (2) The offshore fishing industry in coastal provinces is also in a state of partial carbon neutrality, and the trends of carbon emissions, carbon sinks and net carbon emissions in most provinces are consistent with the national trends, but there are large differences between regions. (3) For the whole country, among the driving factors of net carbon emissions in the offshore fishing industry, industrial development is the main positive driving factor, and population size is the main negative driving factor. The net carbon coefficient and energy intensity also play a certain role in driving net carbon emissions. (4) Population size is an important inhibitory factor for the net carbon emissions of the offshore fishing industry in most coastal provinces, and the driving direction of the net carbon coefficient, energy intensity and industrial development is inconsistent. Based on the above research, relevant suggestions are put forward for the green development of the marine fishing industry

A maximal moment inequality for [alpha]-mixing sequences and its applications

A maximal moment inequality for partial sums of the [alpha]-mixing random variable sequence is established. The inequality uses some moment summations as upper bound. To show the applications of the inequality, we discuss the convergence for [alpha]-mixing sequences, which improves some known results.