Detection of speech signal in strong ship-radiated noise based on spectrum entropy

Comparing the frequency spectrum distributions calculated from several successive frames, the change of the frequency spectrum of speech frames between successive frames is larger than that of the ship-radiated noise. The aim of this work is to propose a novel speech detection algorithm in strong ship-radiated noise. As inaccurate sentence boundaries are a major cause in automatic speech recognition in strong noise background. Hence, based on that characteristic, a new feature repeating pattern of frequency spectrum trend (RPFST) was calculated based on spectrum entropy. Firstly, the speech is detected roughly with the precision of 1 s by calculating the feature RPFST. Then, the detection precision is up to 20 ms, the length of frames, by method of frame shifting. Finally, benchmarked on a large measured data set, the detection accuracy (92 %) is achieved. The experimental results show the feasibility of the algorithm to all kinds of speech and ship-radiated noise

SCFSAP controls organ size by targeting PPD proteins for degradation in Arabidopsis thaliana

Control of organ size by cell proliferation and growth is a fundamental process, but the mechanisms that determine the final size of organs are largely elusive in plants. We have previously revealed that the ubiquitin receptor DA1 regulates organ size by repressing cell proliferation in Arabidopsis. Here we report that a mutant allele of STERILE APETALA (SAP) suppresses the da1-1 mutant phenotype. We show that SAP is an F-box protein that forms part of a SKP1/Cullin/F-box E3 ubiquitin ligase complex and controls organ size by promoting the proliferation of meristemoid cells. Genetic analyses suggest that SAP may act in the same pathway with PEAPOD1 and PEAPOD2, which are negative regulators of meristemoid proliferation, to control organ size, but does so independently of DA1. Further results reveal that SAP physically associates with PEAPOD1 and PEAPOD2, and targets them for degradation. These findings define a molecular mechanism by which SAP and PEAPOD control organ size

A Constitutive Model of Opened Rock Joints in the Field

Mechanical properties of rock joints govern the strength and deformational behaviour of a rock mass. The responses of a rock joint to shear and normal loadings highly depend on its surface properties, block size and matching state. Rock joints can become mismatched or opened due to underground excavation, earthquake vibration and nearby blasting. Previous studies indicate that the opening along joint walls significantly decreases the normal and shear stiffness of a joint, which undermines the stability of rock masses. Nevertheless, the opening effect has not been well considered before in developing constitutive models for the rock joint behaviour. The primary objective of this dissertation is to provide a comprehensive understanding of the mechanical behaviour of field-scale opened joints. A new constitutive model for rock joints with various degrees of opening under both normal and shear loadings is presented. The normal deformability is represented by a semi-empirical non-linear relationship that accounts for the stiffness reduction due to joint opening. A formulation of a joint shear model is developed based on the wear fundamentals. Roughness degradation depends on the relative normal stress and the geometry of the asperity involved in shear. Numerical investigation using UDEC with Voronoi tessellation quantifies how much these parameters affect the dilation behaviour during shear. Experimental curves from both triangular and JRC-shaped joint replicas agree well with the analytical predictions. Scale dependence of the joint roughness is investigated by postulating that a natural joint profile is a self-affine fractal. The proposed scaling laws show that both slopes of waviness and unevenness become gentler with increased sampling length, which has been validated by morphological examinations of several 400 mm long rock joints. The proposed constitutive law has been incorporated into UDEC via the built-in language, FISH. The deformation of three rock structures is assessed by numerical simulations in which the mechanical behaviour of rock joints is represented by the model developed in this study. Good agreement between predictions and field measurements demonstrates the capability of the new joint model for stability analysis of rock masses with opened joints at the field scale