检索结果-南通市图书馆

Nonlinear oscillation of pathological vocal folds during vocalization

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2013年第7期56卷 1324-1328页

作者： wan Ni PENG DanDan SUN Min ZHANG dong Institute of Acoustics Key Laboratory of Modern Acoustics (Nanjing University)Ministry of EducationNanjing University

The extended two-mass model is adopted to analyze the nonlinear oscillation of pathological vocal folds during vocalization. Redundant tissue or area in laryngeal patients is modeled as a massless rigid connected to the upper mass of the vocal folds, and a parameter Q is introduced to represent the change of glottal configurations and tension imbalance between the left and right sides of vocal folds. Numerical simulations demonstrate that the pathological vocal-fold decreases the threshold of Q to generate nonlinear vocal oscillation, indicating the improvement of the sensitivity of vocal folds to asymmetries and enhancing the coupling between two sides. Furthermore, the pathological vocal-fold can lower the fundamental frequency and eliminate high-order harmonics, For example, the fundamental frequency decreases from 119.94 Hz to 84.95 Hz when Q=0.58 and the sub-glottal pressure 1450 Pa. However, there are no prominent effects on the amplitudes of sub-harmonic and low-order harmonics.

关键词： nonlinear oscillation two-mass model asymmetrical vocal fold

Improved Algorithm for Broadcast Scheduling of Minimal Latency in Wireless Ad Hoc Networks

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2010年第1期26卷 13-22页

作者： Wei-ping Shang Peng-jun wan Xiao-dong Hu Department of Mathematics Zhengzhou University Zhengzhou 450052 China Department of Computer Science Illinois Institute of Technology Chicago IL 60616 USA Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

A wide range of applications for wireless ad hoc networks are time-critical and impose stringent requirement on the communication latency. One of the key communication operations is to broadcast a message from a source node. This paper studies the minimum latency broadcast scheduling problem in wireless ad hoc networks under collision-free transmission model. The previously best known algorithm for this NP-hard problem produces a broadcast schedule whose latency is at least 648（rmax/rmin）^2 times that of the optimal schedule, where rmax and rmin are the maximum and minimum transmission ranges of nodes in a network, respectively. We significantly improve this result by proposing a new scheduling algorithm whose approximation performance ratio is at most （1 ＋ 2rmax/rmin）^2＋32, Moreover, under the proposed scheduling each node just needs to forward a message at most once.

关键词： Broadcast latency wireless ad hoc networks approximation algorithm

Numerical simulation of slurry jets using mixture model

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2013年第1期6卷 78-90页

作者： Wen-xin HUAI wan-yun XUE Zhong-dong QIAN State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

Slurry jets in a static uniform environment were simulated with a two-phase mixture model in which flow-particle interactions were considered. A standard k-e turbulence model was chosen to close the governing equations. The computational results were in agreement with previous laboratory measurements. The characteristics of the two-phase flow field and the influences of hydraulic and geometric parameters on the distribution of the slurry jets were analyzed on the basis of the computational results. The calculated results reveal that if the initial velocity of the slurry jet is high, the jet spreads less in the radial direction. When the slurry jet is less influenced by the ambient fluid （when the Stokes number St is relatively large）, the turbulent kinetic energy k and turbulent dissipation rate e, which are relatively concentrated around the jet axis, decrease more rapidly after the slurry jet passes through the nozzle. For different values of St, the radial distributions of streamwise velocity and particle volume fraction are both self-similar and fit a Gaussian profile after the slurry jet fully develops. The decay rate of the particle velocity is lower than that of water velocity along the jet axis, and the axial distributions of the centerline particle streamwise velocity are self-similar along the jet axis. The pattern of particle dispersion depends on the Stokes number St. When St = 0.39, the panicle dispersion along the radial direction is considerable, and the relative velocity is very low due to the low dynamic response time. When St = 3.08, the dispersion of particles along the radial direction is very little, and most of the particles have high relative velocities along the streamwise direction.

关键词： slurry jet," numerical simulation," two-phase mixture model Stokes number,"flow-particle interaction

Structure of Ethanol Coordinated 1,8,15,22-Tetra-(2',2',4'-trimethyl-3'-pentoxy)phthalocyaninatocobalt

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2004年第5期23卷 516-519页

作者： wanGJun-dong HUANGJin-Lin XUXiu-Zhi CAIJin-wan CHENNai-Sheng DepartmentofChemistry FuzhouUniversity StateKeyLaboratoryofStructuralChemistry Fuzhou350002China

Crystal structure of ethanol coordinated 1,8,15,22-tetra(2,2,4-trimethyl-3-pentoxy) phthalocyaninatocobalt (C64H80N8O4Co2C2H5OH, Mr = 1176.43) was determined by X-ray diffrac- tion methods. The crystal is of monoclinic, space group P21/c with a = 16.4294(4), b = 8.0560(2), c = 24.3654(7) ? ?= 98.3680(8)? Z = 2, V = 3190.6(1) ?, Dc = 1.225 g/cm3, F(000) = 1262, (MoK? = 0.326 mm-1, the final R = 0.0865 and wR = 0.2737 for 4787 observed reflections with I ≥ 2(I). The bulky branched alkyloxy substituents lead to a one structural isomer and space the phthalocyanine molecules where two ethanol molecules coordinate to the cobalt atom from two sides of each molecule.

关键词： phthalocyanine substituted phthalocyanine crystal structure

Advanced solar materials for thin-film photovoltaic cells

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2011年第2期6卷 177-196页

作者： Fu-qiang HUANG Chong-yin YANG dong-yun wan College of Engineering and College of Chemistry and Molecular Engineering Peking University Beijing 100871 China CAS Key Laboratory of Materials for Energy Conversion Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou 215123 China

As one of the most promising solutions for the green energy, thin-film photovoltaic cell technology is still immature and far from large-scale industrialization. The major issue is getting low cost and stable module efficiency. To solve these problems, a large amount of advanced solar materials have been developed to improve all parts of solar cell modules. Here, some new solar material developments applied in different critical parts of chalcogenide thin-film photovoltaic cells are reviewed. The main efforts are focused on improving light trapping and antireflection, internal quantum efficiency and collection of photo-generated carriers.

关键词： thin-film solar cell thin films CIGS CdTe

A taxonomic framework for autonomous service management in Service-Oriented Architecture

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第5期13卷 339-354页

作者： Du wan CHEUN Hyun Jung LA Soo dong KIM Department of Computer Science Soongsil University

Since Service-Oriented Architecture (SOA) reveals the black box nature of services,heterogeneity,service dynamism,and service evolvability,managing services is known to be a challenging *** computing (AC) is a way of designing systems that can manage themselves without direct human ***,applying the key disciplines of AC to service management is appealing.A key task of service management is to identify probable causes for symptoms detected and to devise actuation methods that can remedy the *** SOA,there are a number of target elements for service remedies,and there can be a number of causes associated with each target ***,there is not yet a comprehensive taxonomy of causes that is widely *** lack of cause taxonomy results in the limited possibility of remedying the problems in an autonomic *** this paper,we first present a meta-model,extract all target elements for service fault management,and present a computing model for autonomously managing service *** we define fault taxonomy for each target element and inter-relationships among the ***,we show prototype implementation using cause taxonomy and conduct experiments with the prototype for validating its applicability and effectiveness.

关键词： Service-Oriented Architecture (SOA) Autonomic computing (AC) Cause taxonomy Services Faults Causes Adaptation

Reactive diffusion bonding of SiCp/Al composites by insert layers of mixed Al-Si and Al-Si-SiC powders

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2005年第5期12卷 445-449页

作者： Jihua Huang Yueling dong Yun wan Jiangang Zhang Hua Zhang Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

Mixed Al-Si and Al-Si-SiC powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC （metal matrix composites）. The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructtn＇e. Using the mixed Al-Si-SiC powder as the insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer, which results in the bad shear strength of the joints reactive diffusion bonded by the insert layer of the mixed A1-Si- SiC powder, even lower than that of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si powder. Ti and Mg added in the insert layers obviously improve the strength of the joints reactive diffusion bonded by the insert layer of the mixed Al- Si-SiC powder, especially, Mg has a more obvious effect.

关键词： reactive diffusion bonding insert layer SiCp/Al MMCs

Compositional dependence of thermophysical properties in binary alkaline earth borate melts:Insights from structure in short-range and intermediate-range order

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第36期131卷 195-203页

作者： Jian Yang Il sohn Department of Materials Science and Engineering Yonsei UniversitySeoul120749Korea State Key Laboratory of Cemented Carbide Zhuzhou 412000China

In this work,the thermal conductivity of alkaline earth borate melts was measured using hot-wire method from 1323 to 1623 K,and the thermal diffusivity was extrapolated from the thermal conductivity and heat *** compositional dependence of thermophysical properties was interpreted according to the structure in short-range and intermediate-range *** on the Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and 11B magic-angle spinning nuclear magnetic resonance(MAS-NMR)spectra,modifier cation with higher field strength prefers the formation of non-bridging oxygens(NBOs)for the charge compensation at high BO_(1.5)/MO ratios.A lower amount of covalent bond and greater isolation of large borate groups lead to a lower thermal conductivity in calcium borate melt compared with strontium and barium *** the large size of Ba^(2+)encounters difficulty in fitting around B^[4]-OB^[4]linkages inside the overcrowded large borate groups when BO_(1.5)/BaO=2.5,promoting the formation of NBOs on the edge of borate groups for the charge compensation of modifier cations and leading to the decline in the thermal *** conductivity plays a major role in regulating the thermal diffusivity at a given temperature since the compositional dependence of volumetric heat capacity is relatively weak compared with that of thermal conductivity.

关键词： Thermal conductivity Magic-angle spinning nuclear magnetic resonance(MAS-NMR) X-ray photoelectron spectroscopy(XPS) Raman spectroscopy Thermal diffusivity

Lewis Acid Catalyzed Synthesis of Vinylene Linked Two Dimensional Covalent Organic Frameworks

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2022年第15期40卷 1807-1812页

作者： Bai Bin Xiao-Rui Ren dong wang Li-Jun wan CAS Key Laboratory of Molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular SciencesBeijing National Laboratory for Molecular Science(BNLMS)Institute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Comprehensive Summary Vinylene linked covalent organic frameworks(cOFs)have drawn extensive attention due to their desirable stability,carbon conjugation and opto-electronic *** catalyst is a key factor in the synthesis of vinylene linked COFs,and proton acids and bases are widely reported as catalysts so ***,we report the synthesis of vinylene linked cOFs using Lewis acid ZnCl2 as catalyst for the first *** COFs with hexagonal pores of different sizes are synthesized by the reaction of 2,4,6-trimethyl triazine and a series of aromaticaldehydes.

关键词： Covalent organic frameworks Vinylene linkage Lewis acids Zinc chloride Aldol reaction