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Mathematical Modeling of Porous Medium for Sound Absorption Simulations II: Wave Propagation and Interface Conditions

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Journal of Applied Mathematics and Physics 2019年第11期7卷 2780-2795页

作者： Allen Teagle-Hernandez Ortwin Ohtmer Duyen Nguyen Mecahnical and Aerospace Engineering Department California State University Long Beach USA Vibro-Acoustic Department HSEA Technology Inc. Nagoya Japan

The application of porous medium has a myriad of applications in different industries: automotive, aerospace, civil (commercial, residential), environmental noise control, and biomedical. In the past, design questions involving porous material were addressed with seat-of-the-pants decisions that led to multiple/iterative prototypes and experiments that were costly and time consuming. The objective, in this series of publications pertaining to porous medium, is to establish tools that will lead to effective and accurate simulations involving porous medium. In this third installment of this series the focus is on establishing the constitutive equations using tensors and then applying Transfer Matrix Method (TMM) to calculate diffuse field Transmission Loss (TL) across structures that comprises of layers of different porous medium. The constitutive equations are obtained by relating information regarding the micro-structure make-up to macro level properties. In order to apply the TMM, the equations for wave propagation across different mediums need to be developed and in turn represent these propagation properties in a matrix format. Additionally, the boundary condition between each layer type is defined in order to ensure numerical stability. The author’s current research effort is running simulations for the automotive industry to predict NVH environments. Therefore, TL calculations pertaining to the materials that are utilized in the interior of automobiles are used, in this paper, as a test bed for the developed analytical tools. Case in point, the TL for a multi-layered material consisting of one panel and two different layers of foam is calculated and compared to experimental data. Future publication goals will be to apply these tools in the biomedical field;an example will be to model and run simulations of different organs like the liver and lungs that are po-rous in nature.

关键词： Porous Medium multi-scale Homogenization Fluid Structure Interaction

Medical Image Segmentation Based on Wavelet Analysis and Gradient Vector Flow

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Journal of Software Engineering and Applications 2014年第12期7卷 1019-1030页

作者： Ji Zhao Lina Zhang Minmin Yin Department of Software Engineering University of Science and Technology Liaoning Anshan China

Medical image segmentation is one of the key technologies in computer aided diagnosis. Due to the complexity and diversity of medical images, the wavelet multi-scale analysis is introduced into GVF (gradient vector flow) snake model. The modulus values of each scale and phase angle values are calculated using wavelet transform, and the local maximum points of modulus values, which are the contours of the object edges, are obtained along phase angle direction at each scale. Then, location of the edges of the object and segmentation is implemented by GVF snake model. The experiments on some medical images show that the improved algorithm has small amount of computation, fast convergence and good robustness to noise.

关键词： Pattern Recognition Image Segmentation GVF Snake Model Wavelet multi-scale Analysis Medical Image

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2013年1月华北平原重霾成因模拟分析

气候与环境研究 2014年第2期19卷 127-139页

作者：韩霄张美根中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室北京100029

2013年1月华北平原出现了罕见的重污染天气过程，并引发连续多天大范围重霾现象。利用中华人民共和国环境保护部公布的空气污染指数日值数据和气象常规观测数据，结合区域空气质量模式系统RAMS-CMAQ的模拟结果，对1月10～15日污染过程... 详细信息

2013年1月华北平原出现了罕见的重污染天气过程，并引发连续多天大范围重霾现象。利用中华人民共和国环境保护部公布的空气污染指数日值数据和气象常规观测数据，结合区域空气质量模式系统RAMS-CMAQ的模拟结果，对1月10～15日污染过程的气象要素和关键气溶胶物种时空分布特征进行了详细分析，并对灰霾成因进行了探讨。结果表明，受本次污染过程影响的区域主要分布在北京－天津－唐山、河北省中南部和山东省大部。这些地区细颗粒物（即PM2.5）日均质量浓度超过120 μg m-3，且基本被灰霾覆盖，日均能见度在5～8 km之间。其中在北京、天津、石家庄和济南市及周边地区细颗粒物日均质量浓度可达250～300 μg m-3，部分市区可超过300 μg m-3，而日均能见度则可下降至3 km以下，形成重度灰霾。此外，对气象场的分析显示，本次污染过程期间华北平原大部分地区水平风速较多年平均值偏小约20%，且有明显逆温层覆盖，北京－天津－唐山、河北省南部和山东省北部的相对湿度则较多年平均值偏高达10%～40%。这样的气象条件不仅造成污染物易于堆积，而且有利于吸湿性粒子消光效应的快速增长，使能见度明显下降，是引发灰霾的重要因素之一。在北京地区引发灰霾的主要气溶胶物种为硫酸盐、硝酸盐和铵盐，这3种无机盐对近地面的消光贡献比率达到50%以上。其中硝酸盐的消光贡献比率最高，可达总体效应的1/4，表明在这次污染过程中除相关工业源排放外，交通源排放也是北京地区主要的污染源之一。

关键词：灰霾能见度华北平原气象场 CMAQ (Community multi-scale Air Quality modeling system)

Simulation and Analysis of PMSG-based Wind Energy Conversion System using Different Coverter Models

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Engineering（科研） 2013年第1期5卷 96-100页

作者： Hua Ye Juan Su Songhuai Du 1SENSE Lab Technical University of Berlin Berlin Germany Department of Electrical Engineering China Agricultural University Beijing China

Modeling of a permanent magnet synchronous generator (PMSG)-based wind energy conversion system is presented for the simulation of diverse transients. In order to perform multi-scale transients, the back-to-back voltage source converter (VSC) is modeled using three different forms including the detailed, switched and average models. The PMSG-based WECS is implemented in PSCAD/EMTDC. The simulation results show that the detailed and switched model of VSC give a detailed and accurate representation, while the average model provides an efficient simulation.

关键词： Power system simulation PMSG Wind power generation Voltage source converter multi-scale transients

中国高等级旅游景区资源多尺度时空差异及其影响因素

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旅游管理

旅游管理 2023年第2期

作者：张广海袁洪英段若曦董跃蕾

以中国337个地级以上城市内的5A和4A级景区为研究对象，通过构建总体分异指数（GDI）并采用探索性空间数据分析（ESDA）等方法，从省级、城市群、城市等不同空间尺度，对2001—2019年中国高等级旅游景区资源时空演化特征进行综合分析。... 详细信息

以中国337个地级以上城市内的5A和4A级景区为研究对象，通过构建总体分异指数（GDI）并采用探索性空间数据分析（ESDA）等方法，从省级、城市群、城市等不同空间尺度，对2001—2019年中国高等级旅游景区资源时空演化特征进行综合分析。结果表明：（1）4A级景区主导了中国高等级旅游景区数量与增长率的变化趋势，2015年之后增长速度进入相对平缓状态；（2）时序上，中部和东北地区的各省份高等级旅游景区数量较少，但增长率较高，而西部省份则均相对较高，东部省份则是数量最多但增长率最低，到2017年西部超过东部，数量最多；城市规模与高等级旅游景区数量呈正比，与增长率呈反比；（3）空间上，中国高等级旅游景区分布密集程度逐年升高，呈现出主要依托东部沿海地区与中部地区城市群集聚分布的特征，且空间热点、次热点地区占主导地位，形成了“两点集聚-多极多区-集群集聚”的空间演化格局；（4）GDI指数随着研究尺度的缩小而增大，空间尺度越小，高等级旅游景区资源的差异越大；（5）中国高等级旅游景区空间分布主要受社会、经济、资源等因素相互作用的影响，其中人口规模、旅游经济、人文资源是共同的最为关键的因子。研究结果可为优化中国景区资源空间布局以及旅游业高质量及区域协调发展提供一定参考。

关键词：高等级旅游景区资源多尺度时空差异影响因素　　high-level tourist attractions multi-scale spatial and temporal differences influencing factor

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Conference Notice

Water Science and Engineering 2016年第2期9卷 172-172页

The multi-scale Geomechanics and Geo-engineering (MSGG) symposium series serves as a specialized forum to discuss and exchange knowledge pertinent to the most recent theoretical, experimental, computational, and practical advancements in geomechanics and geo-engineering and to inspire explorations on the wide open and unexplored horizons from a multi-scale perspective.

关键词： multi-scale Geomechanics experimental

Improved Retinex Image Enhancement Algorithm

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Improved Retinex Image Enhancement Algorithm

基于个体行为的多尺度城市空间重构及规划应用研究框架

2011 2ND International Conference on Innovative Computing and Communication and 2011 Asia-Pacific Conference on Information Technology and Ocean Engineering(CICC-ITOE 2011)

作者： Ling Tang Shunling Chen Weijun Liu Yonghong Li Sichuan University of Science & Engineering Dept.of Electronic Engineering Sichuan University of Science & Engineering Dept.of Science Engineering Sichuan University of Science & Engineering Computer Application Research of SUSE

Retinex method mainly consists of two steps: estimation and normalization of illumination. How to extract the background illumination accurately is a key problem. The backgrounds of picture sequence in video’s adjacent frames are usually similar and closely related. More accurate illumination information can be extracted when this characteristics of video’s picture sequence is considered. In the paper, we propose an improved Retinex algorithm. Filter the images using the Gauss masks of different scale and parameter for each frame image, and all these filtering results are fused together by minimum method. In the paper, the scale of Gauss filters are set as 5, 9, 13, 25, and their variance set as 0.3, 0.5, 0.7 and 1.0 respectively. 6 adjacent frame images are selected, and the uniform and optical background image for these 6 images can be extracted by maximum method. This method makes use of the similarity and relationship among the adjacent frame images in videos. Enhance the images using Retinex method with this optical background image as their uniform illumination information. Experiment shows that more accurate back grounds are acquired and more excellent enhancement performance are achieved.

关键词： Retinex algorithm multi-scale Information Fusion Monitor Video Background Similarity

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地理 2013年第6期 1-7,14页

作者：柴彦威刘天宝塔娜

中国城市转型面临多尺度的空间重构，从社区、中心城市到都市区、城市群等不同空间尺度。一方面，每个尺度上的空间组织特征及居民行为模式彻底改变；另一方面，一系列社会环境和自然环境问题出现并累积。面对城市发展的新格局和新问题... 详细信息

中国城市转型面临多尺度的空间重构，从社区、中心城市到都市区、城市群等不同空间尺度。一方面，每个尺度上的空间组织特征及居民行为模式彻底改变；另一方面，一系列社会环境和自然环境问题出现并累积。面对城市发展的新格局和新问题，需要依托行为研究，梳理多尺度城市空间的概念体系，揭示其形成机理，判断其环境响应，并以低碳和和谐城市为导向，提出规划策略。具体内容包括：整合GPS、手机、网络、问卷和访谈等多种行为数据，建立中国城市多时空尺度居民行为数据库；分析城市、都市区和城市群尺度的城市空间组织模式和居民行为特征，创建基于个体行为的中国城市空间理论体系和研究范式；解析多尺度城市空间组织及居民行为模式与社会矛盾和碳排放之间的关系；以社会公正、和谐和低碳为导向，提出不同尺度城市空间调整优化策略和居民行为引导策略，面向居民生活质量和城市发展可持续性的提升，推动形成多尺度的居民生活圈和城市空间单元。

关键词：个体行为多尺度城市空间环境响应规划应用　　individual behavior multi-scale urban space environmental response planning application

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生态安全：基于多尺度的考察