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Search Results: 1 - 10 of 36862 matches for " Zhao Zichen "
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Design and Optimization of Comb Drive Accelerator for High Frequency Oscillation  [PDF]
Zichen Zhang
Modern Mechanical Engineering (MME) , 2018, DOI: 10.4236/mme.2018.81001
Abstract: Comb-drive devises have been widely applied in many fields. However, the application of high frequency sensor, such as rocket chamber, still remains problems. In this work, a finite element code was used for the design, optimization and visualization of a comb drive accelerator. In the simulation results, the post-optimization design has high performance in high frequency oscillation operating environment. The optimization is based on the ideal eigenfrequency and Nelder-Mead method. The 3-D working conditions are realized by testing and comparing the time and frequency domain of pre-optimized and optimized design whose frequency ranges from 2000 Hz to 5000 Hz. Finally, the electric potential and capacitance in comb drive are visualized, which shows the better electric signals and displacements.
Synthesis of self-assembled needle-shaped calcium carbonate superstructures
LiNa Zhao,JingDong Feng,XiuYan Wang,ZiChen Wang
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-3283-4
Abstract: Novel self-assembled calcium carbonate (CaCO3) crystals exhibiting the morphology of well-defined needles were synthesized by a simple precipitation reaction in the presence of octadecyl dihydrogen phosphate (ODP) as a crystal additive. The CaCO3 obtained by this method is hydrophobic, making it likely to be used widely in industry. The resulting products were characterized by powder X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle experiments. The results indicated that ODP plays an important role in determining the structure, morphology and hydrophobicity of CaCO3 crystals.
A Comparison of Classifiers in Performing Speaker Accent Recognition Using MFCCs  [PDF]
Zichen Ma, Ernest Fokoué
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.44025
Abstract:

An algorithm involving Mel-Frequency Cepstral Coefficients (MFCCs) is provided to perform signal feature extraction for the task of speaker accent recognition. Then different classifiers are compared based on the MFCC feature. For each signal, the mean vector of MFCC matrix is used as an input vector for pattern recognition. A sample of 330 signals, containing 165 US voice and 165 non-US voice, is analyzed. By comparison, k-nearest neighbors yield the highest average test accuracy, after using a cross-validation of size 500, and least time being used in the computation.

Fabrication of CeO2 by sol-gel process based on microfluidic technology as an analog preparation of ceramic nuclear fuel microspheres
Bin Ye,Jilang Miao,Jiaolong Li,Zichen Zhao,Zhenqi Chang,Christophe A. Serra
Physics , 2012,
Abstract: Microfluidics integrated with sol-gel processes is introduced in preparing monodispersed MOX nuclear fuel microspheres using nonactive cerium as a surrogate for uranium or plutonium. The detailed information about microfluidic devices and sol-gel processes are provided. The effects of viscosity and flow rate of continuous and dispersed phase on size and size distribution of CeO2 microspheres have been investigated. A comprehensive characterization of the CeO2 microspheres has been conducted, including XRD pattern, SEM, density, size and size distribution. The size of prepared monodisperse particles can be controlled precisely in range of 10{\mu}m to 1000{\mu}m and the particle CV is below 3%.
SYNTHESIS AND CHARACTERIZATION OF Ba_(1-x)Pb_x TiO_3 NANOCRYSTALS
纳米晶Ba1—xPbxTiO3的合成与表征

WANG Xiaohui,WANG Zichen,LI Xi,ZHAO Muyu,
王晓慧
,王子忱,李熙,赵慕愚

材料研究学报 , 1994,
Abstract: Ba1-xPbxTiO3 nanocrystals were synthesized by stearic acid-gel method (SAG), using stearic acid, lead acetate, barium stearate and terabutyl titanate as raw materials. The synthesis temperatures were lower than the formation temperature of perovskites ox
Liquid-state fermentation with Bacillus subtilis Bs-07 to enhanceanticoagulant function of Auricularia auricula polysaccharide
Zhang Zhi, Liu Dongmin, Xu Bingxin, Hu Junfei, Liu QiGuo Yong, Liang Zhuoran, Lu Xiangni, Zhao Zichen, Wang Zhenyu
- , 2015, DOI: 10.3969/j.issn.1003-7985.2015.01.024
Abstract: In order to improve the anticoagulant function of Auricularia auricula, Auricularia auricula polysaccharide(AAP)was converted into its derivatives by the microbial fermentation method and then polysaccharide derivatives with stronger anticoagulant activity were prepared. The optimal conditions for fermenting the polysaccharide from A. auricula were examined and the in vitro anticoagulant activities of transformed and untransformed polysaccharides were compared. Response surface tests and an orthogonal experiment indicated that the best conditions for microbial conversion of AAP3 were an AAP3 concentration of 4.0 mg/mL, a ratio of substrate(AAP3)to donor(p-hydroxybenzoic acid)of 40∶1, and a pH of 6.0. Bacillus subtilis Bs-07 was inoculated and then placed on a rotary shaker(120 r/min), followed by fermentation for 48 h at 35 ℃.The conversion rate was found to be greater than 40%. The result of in vitro anticoagulant activity showed that the transformed polysaccharide improved activated partial thromboplastin time, prothrombin time, and thrombin time values and greatly enhanced anticoagulant activity compared to the untransformed polysaccharide.
Local estimates for positive solutions of porous medium equations
Zhongmin Qian,Zichen Zhang
Mathematics , 2014,
Abstract: We derive several new gradient estimates of Aronson-B{\'e}nilan type for positive solutions of porous medium equation and fast diffusion equation on a complete manifold that satisfies the curvature dimension condition
A Comparison of Classifiers in Performing Speaker Accent Recognition Using MFCCs
Zichen Ma,Ernest Fokoue
Computer Science , 2015,
Abstract: An algorithm involving Mel-Frequency Cepstral Coefficients (MFCCs) is provided to perform signal feature extraction for the task of speaker accent recognition. Then different classifiers are compared based on the MFCC feature. For each signal, the mean vector of MFCC matrix is used as an input vector for pattern recognition. A sample of 330 signals, containing 165 US voice and 165 non-US voice, is analyzed. By comparison, k-nearest neighbors yield the highest average test accuracy, after using a cross-validation of size 500, and least time being used in the computation
Bayesian Variable Selection for Linear Regression with the $κ$-$G$ Priors
Zichen Ma,Ernest Fokoué
Statistics , 2015,
Abstract: In this article we develop a new methodology for Bayesian variable selection in multiple linear regression that is independent of the standard indicator vector method. Serving as an extension of Zellner's $g$-prior, we extend the original scalar $g$ to a diagonal matrix $G$ that controls the stability of the prior on the coefficients $\boldsymbol{\beta}$, and each of the elements $g_j$ controls the stability of its corresponding dimension. From the Metropolis-within-Gibbs sampling method, the posterior values of $G$ are sampled and those promising variables tend to have a $g_j$'s that are close to $0$. Thus the promising variables are chosen based on the posterior of $g_j$. As each of the $g_j$'s is a stabilizer of its own dimension, the $1-g_j$ values imitates the posterior inclusion probability (PIP) as in the standard methodology.
Preparation of Ultrafine SiO2 Powders with Large Specific Surface Area
沉淀法合成高比表面积超细SiO2

WANG Zichen,WANG Liwei,ZHAO Jingzhe,YANG Guangli,YANG Hua,ZHAO Muyu,
王子忱
,王莉玮,赵敬哲,杨广丽,杨烨,赵慕愚

无机材料学报 , 1997,
Abstract: 以水玻璃和盐酸为原料,采用化学沉淀法制备出多孔型、高比表面积、超细SiO2,用BET、XRD、SEM、DTA-TGA等手段对其性能进行了表征,结果表明,所制得的多孔型SiO2经表面积可达1000m^2/g以上,孔分布均匀,粒径小,具有许多特殊的性能。
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