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An Algorithm of Voice Activity Detection Based on EMD and Wavelet Entropy Ratio

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Journal of Electronic Science and Technology 2017年第1期15卷 64-68页

作者： Xiao-bing zhang Ting-Ting Sun Yan-Ping School of Electrical and Information Engineering Anhui University of TechnologyMaanshan 243000China

A new method was proposed to identify speech-segment endpoints based on the empirical mode decomposition（EMD） and a new wavelet entropy ratio with improving the accuracy of voice activity *** the EMD, the noise signals can be decomposed into several intrinsic mode functions（IMFs）. Then the proposed wavelet energy entropy ratio can be used to extract the desired feature for each IMFs component. In view of the question that the method of voice endpoint detection based on the original wavelet entropy ratio cannot adapt to the low signal-to-noise ratio（SNR）condition, an appropriate positive constant was introduced to the basic wavelet energy entropy ratio with effectively improved discriminability between the speech and noise. After comparing the traditional wavelet energy entropy ratio with the proposed wavelet energy entropy ratio, the experiment results show that the proposed method is simple and fast. The speech endpoints can be accurately detected in low SNR environments.

关键词： wavelet entropy decomposed Wavelet adapt environments Voice noisy empirical desired

Effect of small bowel preparation with simethicone on capsule endoscopy

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第1期10卷 46-51页

作者： You-hong FANG Chun-xiao CHEN bing-ling zhang The Children's Hospital School of Medicine Zhejiang University Hangzhou 310003 China Department of Gastroenterology the First Affiliated Hospital School of Medicine Zhejiang University Hangzhou 310003 China

Background： Capsule endoscopy is a novel non-invasive method for visualization of the entire small bowel. The diagnostic yield of capsule endoscopy depends on the quality of visualization of the small bowel mucosa and its complete passage through the small bowel. To date, there is no standardized protocol for bowel preparation before capsule endoscopy. The addition of simethicone in the bowel preparation for the purpose of reducing air bubbles in the intestinal lumen had only been studied by a few investigators. Methods： Sixty-four participants were randomly divided into two groups to receive a bowel preparation of polyethylene glycol （PEG） solution （Group 1） and both PEG solution and simethicone （Group 2）. The PEG solution and sime- thicone were taken the night before and 20 rain prior to capsule endoscopy, respectively. Frames taken in the small intestine were examined and scored for luminal bubbles by two professional capsule endoscopists. Gastric emptying time and small bowel transit time were also recorded. Results： Simethicone significantly reduced luminal bubbles both in the proximal and distal small intes- tines. The mean time proportions with slight bubbles in the proximal and distal intestines in Group 2 were 97.1% and 99.0%, respectively, compared with 67.2% （P〈0.001） and 68.8% （P〈0.001） in Group 1. Simethicone had no effect on mean gastric emptying time, 32.08 rain in Group 2 compared with 30.88 min in Group 1 （P=0.868）, but it did increase mean small intestinal transit time from 227.28 to 281.84 rnin （P=0.003）. Conclusion： Bowel preparation with both PEG and simethicone significantly reduced bubbles in the intestinal lumen and improved the visualization of the small bowel by capsule endoscopy without any side effects observed.

关键词： Capsule endoscopy Bowel preparation Simethicone Polyethylene glycol (PEG) Visualization Air bubbles

Recrystallization of SRR99 single-crystal superalloy: Kinetics and microstructural evolution

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Rare Metals 2010年第3期29卷 312-316页

作者： zhang bing LIU Changkui HE Yuhuai TAO Chunhu LU Xin Failure Analysis Center of AVIC Beijing Institute of Aeronautical Materials Beijing 100095 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

As-cast SRR99 specimens were shot-peened and then annealed at 1250 and 1300°C for different times to investigate the kinetics of *** was found that the relationship between annealing time and volume fraction of recrystallized grains could be described by the Johnson-Mehl-Avrami *** on the kinetics analysis of the recrystallization process,the apparent activation energy for recrystallization was *** addition,the microstructural evolution during the recrystallization process at 1300°C was ***,recrystallization first occurs in the dendritic core regions at the shot-peened *** the dissolution of coarse γ＇ particles in the interdendritic regions,the recrystallized grain boundaries move through the interdendritic ***,the fully developed grains nearly have a uniform *** recrystallization process at the shot-peened surface is similar to that of wrought materials,which includes nucleation of recrystallization,growth of recrystallized nuclei into the matrix,and growth of recrystallized grains by swallowing up each other.

关键词： single crystal superalloy recrystallization shot peening activation energy kinetics

Nonlinear Interaction and Entanglement Transfer from SU(1,1) Coherent State to Mixed Atoms

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Communications in Theoretical Physics 2008年第1期49卷 83-87页

作者： zhang Jin-Hua LIANG Mai-Lin YUAN bing zhang Fu-Lin Physics Department School of Science Tianjin University Tianjin 300072 China

For nonlinear interactions with different forms of intensity-dependent coupling, entanglement transfer from the correlated two-mode SU（1,1） coherent states （SCS） to the initially separable and mixed atoms is investigated. It is found that suitable intensity-dependent coupling can enhance the entanglement transfer and make the atomic entanglement evolve periodically especially for the initially mixed atomic states. For SCS, the entanglement between the two modes is strengthened with the increase of the photon number difference （PND） between the two modes of the fields. When PND is odd, the entanglement between the atoms is less than that when PND is even.

关键词： entanglement transfer intensity-dependent coupling SU(1 1) coherent state mixed atomic states

Long-term multi-wavelength variations of Fermi blazar 3C 279

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Research in Astronomy and Astrophysics 2021年第8期21卷 5-15页

作者： bing-Kai zhang Min Jin Xiao-Yun Zhao Li zhang Ben-Zhong Dai Department of Physics Fuyang Normal UniversityFuyang 236037China Key Laboratory of Functional Materials and Devices for Informatics of Anhui Higher Education Institutes Fuyang Normal UniversityFuyang 236037China Department of Astronomy Yunnan UniversityKunming 650091China

Long-term optical,X-ray and γ-ray data of blazar 3 C 279 have been compiled from Swift-XRT,RXTE-PCA,Fermi-LAT,SMARTS and *** source exhibits strong variability on long *** the 1980 s until now,the optical R band light curve spans more than 32 yr,and a possible 5.6-yr-long quasi-periodic variation component has been found in *** optical spectral behavior has been *** the optical band,the mean spectral index is –*** source exhibits an obvious special spectral *** the low state,the source manifests a clear bluer-when-brighter behavior in the sense that the optical spectrum turns harder(flatter) when the brightness *** in the high state,the optical spectrum is stable,which means the source spectral index does not vary with *** correlation analysis has been performed among optical,X-ray and γ-ray energy *** result indicates that the variations of γ-ray and X-ray bands are well correlated without time delay on the timescale of days,and their variations exhibit weak correlations with those of the optical *** variations,especially outbursts,are simultaneous,but the magnitude of variations is *** detailed analysis reveals that the main outbursts exhibit strong correlations in different γ-ray,X-ray and optical bands.

关键词： galaxies:active BL Lacertae objects:general quasars:general quasars:individual(3C 279)

Thermoelectric properties of quaternary Mg_2Sn_(0.4)Si_(0.6-x)Ge_x alloys

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International Journal of Minerals,Metallurgy and Materials 2009年第5期16卷 564-567页

作者： Hao Yin Xin-bing Zhao Qian zhang Tie-Jun Zhu State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China

Quaternary alloys Mg2Sn0.4Si0.6-xGex （x=0, 0.02, 0.05, 0.08 0.1, and 0.2） were prepared using induction melting followed by hot-pressing. Relative densities of the sintered samples were over 97% of the theoretical values. Multiple phases were detected in the samples. It was found that the Seebeck coefficient was sensitive to the content of Mg2Ge and a maximum value of about 350 μV-K^-1 was obtained. The introduction of Ge increases the electrical conductivity and the thermal conductivity simultaneously. The mechanism of this phenomenon was discussed. A maximum dimensionless figure of merit, ZT, of about 0.28 was obtained for Mg2Sn0.4Si0.55Ge0.05 at 550 K.

关键词： thermoelectric materials hot-pressing thermal conductivity induction melting quaternary alloys

Progress and Prospects of Hydrogen Production: Opportunities and Challenges

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Journal of Electronic Science and Technology 2021年第2期19卷 97-118页

作者： bing zhang Sui-Xin zhang Rui Yao Yong-Hong Wu Jie-Shan Qiu School of Petrochemical Engineering Shenyang University of TechnologyLiaoyang 111003 College of Chemical Engineering Beijing University of Chemical TechnologyBeijing 100029

This study presents an overview of the current status of hydrogen production in relation to the global requirement for energy and ***,it symmetrically outlines the advantages and disadvantages of various production routes including fossil fuel/biomass conversion,water electrolysis,microbial fermentation,and photocatalysis(PC),in terms of their technologies,economy,energy consumption,and *** the characteristics of hydrogen energy and the current infrastructure issues,it highlights that onsite production is indispensable and convenient for some special ***,it briefly summarizes the current industrialization situation and presents future development and research directions,such as theoretical research strengthening,renewable raw material development,process coupling,and sustainable energy use.

关键词： Electrolysis fermentation hydrogen production photocatalysis(PC) process integration renewable resource sustainable energy

Nitrogen-doped graphene microtubes with opened inner voids: Highly efficient metal-free electrocatalysts for alkaline hydrogen evolution reaction

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Nano Research 2016年第9期9卷 2606-2615页

作者： bing zhang Hong-Hui Wang Hui Su Li-bing Lv Tian-Jian Zhao Jie-Min Ge Xiao Wei School of Chemistry and Chemical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

A facile method was developed to fabricate nitrogen-doped graphene microtubes (N-GMT) with ultra-thin walls of 1–4 nm and large inner voids of 1–2 μm. The successful introduction of nitrogen dopants afforded N-GMT more active sites for significantly enhanced hydrogen evolution reaction (HER) activity, achieving a current density of 10 mA·cm–2at overpotentials of 0.464 and 0.426 V vs. RHE in 0.1 and 6 M KOH solution, respectively. This HER performance surpassed that of the best metal-free catalyst reported in basic solution, further illustrating the great potential of N-GMT as an efficient HER catalyst for real applications in water splitting and chlor-alkali processes. [Figure not available: see fulltext.] © 2015, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： graphene microtubes green chemistry hydrogen evolution reaction water splitting

ZnGa_(2)S_(4):an infrared nonlinear optical material with large second-harmonic generation response and wide band gap

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Rare Metals 2024年第1期43卷 395-401页

作者： Chen-Yang zhang Xiao-Nan Niu Yan-Feng Wei Shu-Xing Zhou Da-Qing Yang Ying Wang Jian Wang bing-bing zhang College of Chemistry and Materials Science Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of EducationState Key Laboratory of New Pharmaceutical Preparations and ExcipientsHebei UniversityBaoding 071002China Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and ScienceXiangyang 441053China Hubei Longzhong Laboratory Xiangyang 441000China Department of Chemistry and Biochemistry Wichita State UniversityKansas 67260USA

High-performance nonlinear optical(NLO)crystals are crucial devices to convert wavelength of solid-state *** play an indispensable role in the research of infrared NLO *** this work,ternary chalcogenide ZnGa_(2)S_(4) ... 详细信息

关键词： optical nonlinear harmonic