BIOMECHANICS ANALYSIS OF FORWARD HANDSPRING AND SALTO STRETCHED WITH 5/2 TWIST IN VAULTING

The purpose of this study was to provide biomechanical analysis of the vault, Handspring Forward and Salto Forward Stretched with 5/2 Twist (Vault Number 2538). This routine was considered one of the most superior moves in recent international gymnastics competitions. It has a high degree of difficulty and its execution results in a base score of 10. In this paper, analysis of the Conservation of Angular Momentum was obtained. In addition, Coriolis’s moment of inertia momentum and conical-curve movement of the legs in opposite direction of this movement was calculated to obtain the technique for approach and for technical requirements. The data collected would provide information for athletes in their training

2D Be3B2C3\rm\bf {Be_{3}B_{2}C_{3}}:a stable direct-bandgap semiconductor with record-breaking carrier mobility, 8.1×105cm2V−1s−1\rm\bf 8.1 \times 10^{5} cm^{2}V^{-1}s^{-1}

The Moore's law in the semiconducting industry has faltered as the three-dimensional (3D) Si-based transistors has approached their physical limit with the downscaling. The carrier mobility $\rm \mu$, critical to the device's performance, will be degraded when the thickness of Si is scaled into several nanometers. In contrast to the bulk counterpart, two-dimensional (2D) semiconductors can be scaled into atomic-layer thickness without dangling bonds, maintaining its intrinsic carrier mobility and going beyond the limits of Si-based electronics. Hence, the development of novel 2D semiconducting materials with high carrier mobility is the market demand as well as the scientific challenge. Here, we successfully designed 2D $\rm {Be_{3}B_{2}C_{3}}$ with planar hypercoordinate motif. It possesses the perfect planar skeleton with both pentacoordinate carbon and hexacoordinate boron moieties, which is the first reported material with such multi-hypercoordinate centers. Density functional theory (DFT) calculations prove that the $\rm {Be_{3}B_{2}C_{3}}$ monolayer has excellent structural and thermal stabilities as well as mechanical properties. Further investigations reveal that the $\rm {Be_{3}B_{2}C_{3}}$ monolayer has a strong ultrahigh Fermi velocity ($\rm 2.7 \times 10^{5} m/s$), suitable direct bandgap (1.97 eV), and high optical absorption coefficient ($\rm 10^{5}$). As a result, an unprecedented ultrahigh room-temperature carrier mobility ($\rm 8.1 \times 10^{5} cm^{2}V^{-1}s^{-1}$) with strong anisotropy is discovered, making $\rm {Be_{3}B_{2}C_{3}}$ monolayer a revolutionary candidate for future electronic and photovoltaic applications.Comment: 16 pages, 4 figures, 1 tabl

Surface Defect Classification for Hot-Rolled Steel Strips by Selectively Dominant Local Binary Patterns

Developments in defect descriptors and computer vision-based algorithms for automatic optical inspection (AOI) allows for further development in image-based measurements. Defect classification is a vital part of an optical-imaging-based surface quality measuring instrument. The high-speed production rhythm of hot continuous rolling requires an ultra-rapid response to every component as well as algorithms in AOI instrument. In this paper, a simple, fast, yet robust texture descriptor, namely selectively dominant local binary patterns (SDLBPs), is proposed for defect classification. First, an intelligent searching algorithm with a quantitative thresholding mechanism is built to excavate the dominant non-uniform patterns (DNUPs). Second, two convertible schemes of pattern code mapping are developed for binary encoding of all uniform patterns and DNUPs. Third, feature extraction is carried out under SDLBP framework. Finally, an adaptive region weighting method is built for further strengthening the original nearest neighbor classifier in the feature matching stage. The extensive experiments carried out on an open texture database (Outex) and an actual surface defect database (Dragon) indicates that our proposed SDLBP yields promising performance on both classification accuracy and time efficiencyPeer reviewe

Clinical features of X linked juvenile retinoschisis in Chinese families associated with novel mutations in the RS1 gene

Purpose: To describe the clinical phenotype of X linked juvenile retinoschisis (XLRS) in 12 Chinese families with 11 different mutations in the XLRS1 (RS1) gene. Methods: Complete ophthalmic examinations were carried out in 29 affected males (12 probands), 38 heterozygous females carriers, and 100 controls. The coding regions of the RS1 gene that encodes retinoschisin were amplified by polymerase chain reaction and directly sequenced. Results: Of the 29 male participants, 28 (96.6%) displayed typical foveal schisis. Eleven different RS1 mutations were identified in 12 families; four of these mutations, two frameshift mutations (26 del T of exon 1 and 488 del G of exon 5), and two missense mutations (Asp145His and Arg156Gly) of exon 5, had not been previously described. One non-disease-related polymorphism (NSP): 576C to T (Pro192Pro) change was also newly reported herein. We compared genotypes and observed more severe clinical features in families with the following mutations: frameshift mutation (26 del T) of exon 1, the splice donor site mutation (IVS1+2T to C),or Arg102Gln, Arg209His, and Arg213Gln mutations. Conclusions: Severe XLRS phenotypes are associated with the frameshift mutation 26 del T, splice donor site mutation (IVS1+2T to C), and Arg102Gln, Asp145His, Arg209His, and Arg213Gln mutations. The wide variability in the phenotype in Chinese patients with XLRS and different mutations in the RS1 gene is described. Identification of mutations in the RS1 gene and expanded information on clinical manifestations will facilitate early diagnosis, appropriate early therapy, and genetic counseling regarding the prognosis of XLRS.Biochemistry & Molecular BiologyOphthalmologySCI(E)PubMed12ARTICLE88804-8121

Systematic evaluation for multi-rate simulation of DC Grids

With wide applications of power electronic devices in modern power systems, simulation using traditional electromechanical and electromagnetic tools suffers low speed and imprecision. Multi-rate methods can enhance efficiency of simulation by decreasing the scale of systems in small time-steps. However, the existing traditional methods for multi-rate simulation suffer the problems of instability and simulation errors. These have hindered the application of multi-rate simulation in power industry. Therefore theoretical evaluation on different multi-rate simulation methods is crucial to understand the feasibility and limitation of the methods, and to contribute to overcome the drawbacks of the traditional methods. In this paper, the multi-rate simulation performance based on two traditional technologies and a Modified Thevenin Interface are evaluated to provide an overall feasibility of multi-rate algorithms in the power simulation. The Modified Thevenin Interface is proposed to overcome the drawbacks in synchronization. Three theorems are proposed and proved for theoretically analyzing the stability of the simulation methods. Error analyses of the multi-rate methods are performed to identify the relationships between errors and simulation conditions. Besides, the accuracy and efficiency performance in a practical project of VSC-MTDC shows the feasibility and necessity by using multi-rate simulation. Through the theoretical analysis, the issues of stability and accuracy of multi-rate simulation for the DC grids have been better understood, based on which an improved simulation algorithm has been proposed to overcome these issues. Long-term system dynamics of large-scale systems containing DC grids and fast transients of HVDC converters can be investigated simultaneously with high speed and sufficient accuracy

Subspaces of interval maps related to the topological entropy

For $a\in [0,+\infty)$, the function space $E_{\geq a}$ ($E_{>a}$; $E_{\leq a}$; $E_{<a}$) of all continuous maps from $[0,1]$ to itself whose topological entropies are larger than or equal to $a$ (larger than $a$; smaller than or equal to $a$; smaller than $a$) with the supremum metric is investigated. It is shown that the spaces $E_{\geq a}$ and $E_{>a}$ are homeomorphic to the Hilbert space $l_2$ and the spaces $E_{\leq a}$ and $E_{<a}$ are contractible. Moreover, the subspaces of $E_{\leq a}$ and $E_{<a}$ consisting of all piecewise monotone maps are homotopy dense in them, respectively.Comment: 12 pages, 1 figure, to appear in Topol. Methods Nonlinear Ana

Effect of chromatic dispersion induced chirp on the temporal coherence property of individual beam from spontaneous four wave mixing

Temporal coherence of individual signal or idler beam, determined by the spectral correlation property of photon pairs, is important for realizing quantum interference among independent sources. To understand the effect of chirp on the temporal coherence property, two series of experiments are investigated by introducing different amount of chirp into either the pulsed pump or individual signal (idler) beam. In the first one, based on spontaneous four wave mixing in a piece of optical fiber, the intensity correlation function of the filtered individual signal beam, which characterizes the degree of temporal coherence, is measured as a function of the chirp of pump. The results demonstrate that the chirp of pump pulses decreases the degree of temporal coherence. In the second one, a Hong-Ou-Mandel type two-photon interference experiment with the signal beams generated in two different fibers is carried out. The results illustrate that the chirp of individual beam does not change the temporal coherence degree, but affect the temporal mode matching. To achieve high visibility, apart from improving the coherence degree by minimizing the chirp of pump, mode matching should be optimized by managing the chirps of individual beams.Comment: 17pages, 4figure

An all fiber source of frequency entangled photon pairs

We present an all fiber source of frequency entangled photon pairs by using four wave mixing in a Sagnac fiber loop. Special care is taken to suppress the impurity of the frequency entanglement by cooling the fiber and by matching the polarization modes of the photon pairs counter-propagating in the fiber loop. Coincidence detection of signal and idler photons, which are created in pair and in different spatial modes of the fiber loop, shows the quantum interference in the form of spatial beating, while the single counts of the individual signal (idler) photons keep constant. When the production rate of photon pairs is about 0.013 pairs/pulse, the envelope of the quantum interference reveals a visibility of $(95\pm 2)$, which is close to the calculated theoretical limit 97.4%Comment: 11 pages, 6 figures, to appear in Phys. Rev.