检索结果-内蒙古大学图书馆

Influences of initial velocity,diameter and Reynolds number on a circular turbulent air/air jet

Chinese Physics B 2011年第12期20卷 273-278页

作者：米建春杜诚 State Key Laboratory of Turbulence and Complex Systems Peking University Department of Energy and Resources Engineering College of EngineeringPeking University

This paper assesses the suitability of the inflow Reynolds number defined by Reo -- UoD/v （here Uo and D are respectively the initial jet velocity and diameter while v is kinematic viscosity） for a round air/air jet. Specifically an experimental investigation is performed for the influences of Uo, D and Reo on the mean-velocity decay and spread coefficients （Ku, Kr） in the far field of a circular air jet into air from a smoothly contracting nozzle. Present measurements agree well with those previously obtained under similar inflow conditions. The relations Ku ∝ Uo and Kr ∝ 1/Uo for Uo 〈 5 m/s appear to work, while each coefficient approaches asymptotically to a constant for Uo 〉 6 m/s, regardless of the magnitudes of Reo and D. It is revealed that Reo may not be an appropriate dimensionless parameter to characterize the entire flow of a free air/air jet. This paper is the first paper that has challenged the suitability of Reo for turbulent free jets.

关键词： turbulent jet momentum conservation Reynolds number

来源：评论

学校读者我要写书评

暂无评论

A novel HHT and nonlinear teager energy operator based feature for speech emotion recognition

引用

International Review on Computers and software 2012年第6期7卷 3360-3364页

作者： Zhang, Guobao Li, Yue Huang, Yongming School of Automation Southeast University Nanjing Jiangsu 210096 China Key Laboratory of Measurement and Control of Complex Systems of Engineering Ministry of Education Nanjing China School of Automation Southeast University Nanjing Jiangsu 210096 China

In traditional speech emotion recognition researches, speech is modeled as linear and short-term stationary signal, with Fourier analysis used as the foundation of speech signal processing and feature extraction. To overcome this shortage, in this paper the Hilbert-Huang transform, which works well for non-stationary and nonlinear data, is used for speech signal processing, and combined with the nonlinear Teager energy operator to put forward a novel spectral feature: Hilbert-Teager Subband Energy Cepstral Coefficients, HT-SECC. With Gaussian mixture model used for classification, the experimental results on Berlin emotional speech corpus show that the HT-SECC feature outperforms traditional Mel-Frequency Cepstral Coefficients and prosodic features. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.

关键词： Hilbert-Huang transform

来源：评论

学校读者我要写书评

暂无评论

Observer-Based Containment Control of Multi-Agent System with Linear Dynamics

Observer-Based Containment Control of Multi-Agent System wit...

引用

The 24th Chinese Control and Decision Conference (第24届中国控制与决策学术年会 2012 CCDC)

作者： Zonggang Li Guangming Xie Pu Gao School of Mechatronic Engineering Lanzhou Jiaotong University Lanzhou 730070 China Center for Sy Center for Systems and Control State Key Laboratory of Turbulance and Complex Systems College of E School of Mechatronic Engineering Lanzhou Jiaotong University Lanzhou 730070 China

This paper considers the containment control of linear multi-agent system with weakly connected information topology. By defining the node-induced strongly connected subgraph as strong component, the agents contained in strong components with zero in-degree are called leaders and the others are called followers. Then, a sufficient and necessary condition is proposed for all agents to achieve containment by employing an observer-based protocol, where all followers finally converge to the convex hull formed by leaders and each strong component of leaders asymptotically achieve consensus. Since the number of leader agents in each strong component are always larger than one, the proposed scheme is more robust for the malfunction of leaders. Further, two LMIs are given to design the observer-based protocol. Numerical examples are included to illustrate the validity of the proposed results.

关键词： Multi-agent system Observer-based Containment Control Consensus.

来源：评论

学校读者我要写书评

暂无评论

Damage detection method in complicated beams with varying flexural stiffness

引用

Applied Mathematics and Mechanics(English Edition) 2011年第4期32卷 469-478页

作者：冯侃励争高桂云苏先樾 Department of Mechanics and Aerospace Engineering State Key Laboratory for Turbulence and Complex SystemsCollege of EngineeringPeking University

A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method （SSEM）, and its applicability condition is introduced. For a beam with the continuously varying fiexural stiffness and an edge crack, the SSEM is used to detect the crack location effectively by numerical modal shapes. As a complicated beam, the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis. The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully. The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.

关键词： nondestructive testing modal strain energy varying flexural stiffness beam fiber reinforced composite material wind turbine blade

来源：评论

学校读者我要写书评

暂无评论

Effect of turbulence intensity on airfoil flow:numerical simulations and experimental measurements

引用

Applied Mathematics and Mechanics(English Edition) 2011年第8期32卷 1029-1038页

作者：李韵武王庶王健平米建春 Department of Mechanics and Aerospace Engineering State Key Laboratory on Turbulence and Complex Systems College of Engineering Peking University

The effect of the turbulence intensity of the oncoming stream on the aerodynamic characteristics of the NACA-0012 airfoil is investigated by a direct numerical simulation. The numerical results are found to be consistent with the experimental measurements. Based on the finite spectral QUICK scheme, the simulation gets the high accuracy results. Both the simulation and the experiment reveal that the airfoil stall does not exist for the low turbulence intensity, however, occurs when the turbulence intensity increases sufficiently. Besides, the turbulence intensity has a significant effect on both the airfoil boundary layer and the separated shear layer.

关键词： finite spectral method turbulence intensity boundary layer shear layer lift force drag force airfoil stall

来源：评论

学校读者我要写书评

暂无评论

Design and implementation of a wireless video sensor network

Design and implementation of a wireless video sensor network

引用

IEEE International Conference on Networking, Sensing and Control

作者： Bin Tian Xue-Liang Zhao Qing-Ming Yao Lei Zha State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China Jiangsu China Sciences Intelligent Engineering Company Limited Suzhou China

As a new research field in wireless sensor network (WSN), wireless video sensor network (WVSN) makes surveillance multifunctional and intelligent, with rich and intuitive sensing information. It attracts more and more researchers' attention. We design and implement a wireless video sensor network prototype system, using WIFI as the wireless communication solution and CMOS video camera as the front-end sensor. The wireless video node adopts ARM11 based embedded platform. As back-end processing algorithm, the node realizes moving object detection. Finally, we verify the sensor network system. WIFI network can transmit video sequences smoothly. The moving object detection algorithm performs well.

关键词： Wireless communication Wireless sensor networks IEEE 802.11 Standards Object detection Program processors CMOS integrated circuits Cameras

来源：评论

学校读者我要写书评

暂无评论

An overview of agent-based evacuation models for building fires

An overview of agent-based evacuation models for building fi...

引用

IEEE International Conference on Networking, Sensing and Control

作者： Yuling Hu Xiwei Liu Feiyue Wang Changjian Cheng Beijing Key Laboratory of Automatic Control System School of Automation Beijing Institute of Technology. and School of Electric and Information Engineering Beijing University of Civil Engineering and Architecture China State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences China

Agent-based evacuation modeling approach is gained more and more attention for investigating human cognitive capabilities and social behaviors in building fires. This paper mainly overviews the research about various agent-based evacuation models. For the decision-making reflects the intelligence of agent individual, we define three types of behavior decision-making models for agent individual based on the collected literatures and sum up the characteristics of each type. Aiming at crowd' important influence on evacuation processes, we also sum up two types of agent-based crowd modeling approaches to simulate crowd evacuation processes and give corresponding cases. Finally, after summing up the existing problems, the outlooks of the research from computational experiments point of view is proposed.

关键词： Computational modeling Fires Biological system modeling Buildings Decision making Humans Adaptation models

来源：评论

学校读者我要写书评

暂无评论

Developing Objective SensitivityAnalysis of Periodic systems： Case Studies of Biological Oscillators

引用

自动化学报 2012年第7期38卷 1065-1073页

作者： LU Bao-Yun YUE Hong Key Laboratory of Complex Systems and Intelligence Science Institute of AutomationChinese Academy of SciencesBeijing 100190P.R.China College of Computer Science and Technology Henan Polytechnic UniversityJiaozuo 454000P.R.China Department of Electronic and Electrical Engineering University of StrathclydeGlasgowG11QEUK

Abstract Sensitivity analysis is a powerful tool in investigating the impact of parameter variations on the change of system behaviours quantitatively. For a periodic system, sensitivity analysis is a challenging problem since the standard sensitivity metrics grow unbounded when time tends to infinity. Objective sensitivity analyses using various oscillation features such as period, phase, amplitude, etc. are therefore needed to circumvent this problem. In this work, a new concept of basal state sensitivity is proposed based on which a phase sensitivity calculation is derived. The improved period sensitivity calculation following an existing algorithm using singular value decomposition (SVD) is also presented, which provides a simple calculation for the basal state sensitivity. These new sensitivity calculations are developed with the purpose to analyse biological oscillators since there is an increasing interest in understanding how oscillations occur and what the main controlling factors are following a growing experimental and computational evidence of oscillations in biological systems. The improved calculation of period sensitivity is shown to be consistent with the previous methods through a well studied circadian rhythm model. The calculation of new objective sensitivities are also testified by the same circadian rhythm model as well as an oscillatory signal transduction pathway model, which further illustrates the efficiency of this approach in handling complex biological oscillators in the presence of reaction conservations.

关键词：周期系统生物系统振荡器敏感性分析灵敏度指标案例开发信号转导通路

来源：评论

学校读者我要写书评

暂无评论

Formation of efficient dye-sensitized solar cells by introducing an interfacial layer of hierarchically ordered macro-mesoporous TiO_2 film

引用

Science China Chemistry 2011年第6期54卷 930-935页

作者： HALPERT Jonathan E State Key Laboratory of Multi-phase Complex Systems Institute of Process Engineering Chinese Academy of Sciences

Hierarchically ordered macro-mesoporous TiO2 films (Ti-Ma-Me) were fabricated on fluorine-doped tin oxide (FTO) substrates through the confinement self-assembly method. The prepared Ti-Ma-Me possesses periodically ordered structure and a large specific surface area, which was applied as an interfacial layer between the nanocrystalline TiO2 film (P25-TiO2) and FTO electrode in the dye-sensitized solar cell (DSSC). The introduction of a Ti-Ma-Me interfacial layer increased the shortcircuit current density (Jsc) from 7.49 to 10.65 mA/cm2 and the open-circuit voltage (Voc) from 0.65 to 0.70 V as the result of its improved light harvesting efficiency by allowing for the high roughness factor and enhanced multiple internal reflection or scattering as well as reducing the back-transport reaction by blocking direct contact between the electrolyte and FTO electrode. Therefore, the photovoltaic conversion efficiency (η) was improved by 83% from 3.04% to 5.55%, as compared to a device using a bare P25 TiO2 photoanode.

关键词： dye-sensitized solar cells hierarchical ordered macro-mesoporous photoanode

来源：评论

学校读者我要写书评

暂无评论

Unscented Particle Filter with Systematic Resampling Localization Algorithm Based on RSS for Mobile Wireless Sensor Networks

Unscented Particle Filter with Systematic Resampling Localiz...

引用

International Conference on Mobile Ad-hoc and Sensor Networks, MSN

作者： Zhengjie Wang Xiaoguang Zhao Xu Qian School of Mechanical Electronic & Information Engineering China University of Mining & Technology (Beijing) Beijing China State Key Laboratory of Management and Control for Complex Systems Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781467358088

We consider the problem of mobile sensor node localization and propose an unscented particle filter algorithm in wireless sensor networks (WSNs) consisting of mobile nodes and static anchor nodes. Because the received signal strength (RSS) varies obviously, we employ particle filter to decrease the bad effect. We first form the system state model, mobile model, and RSS model, and then apply unscented particle filter and utilize the systematic resample to decrease the degeneration of the particle. We eliminate the uncertain of the RSS in wireless channel and get accurate location of mobile nodes. The predicted position of the mobile node is constrained by its velocity and the measurement value of RSS. We do a lot of simulation to validate the algorithm by assigning different parameters. Simulation results show that the algorithm enhances the localization accuracy of mobile node compared with the standard particle filter algorithm.

关键词： Mobile wireless sensor networks Localization Received signal strength (RSS) Unscented particle filter Systematic resampling Wireless sensor networks RSS gene Really Simple Syndication REACTOR SAFETY STUDY Particle filters Particle filtering algorithm Mobile Mobile nodes Resampling Values in measurement wireless channels

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：