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Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation 被引量:9
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作者 包伯成 许建平 刘中 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第11期4742-4747,共6页
By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in dis... By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagrazn, Lyapunov exponent spectrum, time- domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region. 展开更多
关键词 buck-boost converter iterative map model mode shift ramp compensation
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HYPERSTATIC STRUCTURE MAPPING MODEL BUILDING AND OPTIMIZING DESIGN 被引量:2
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作者 XU Gening GAO Youshan +1 位作者 ZHANG Xueliang YANG Ruigang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2007年第1期55-59,共5页
Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method (FEM) analysis commerce software. M... Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method (FEM) analysis commerce software. Mapping model of complex structure system is set up, with convenient calculation just as in plane model and comprehensive information as in space model. Plane model and space model are calculated under the same working condition. Plane model modular construction inner force is considered as input data; Space model modular construction inner force is considered as output data. Thus specimen is built on input data and output dam. Character and affiliation are extracted through training specimen, with the employment of nonlinear mapping capability of the artificial neural network. Mapping model with interpolation and extrpolation is gained, laying the foundation for optimum design. The steel structure of high-layer parking system (SSHLPS) is calculated as an instance. A three-layer back-propagation (BP) net including one hidden layer is constructed with nine input nodes and eight output nodes for a five-layer SSHLPS. The three-layer structure optimization result through the mapping model interpolation contrasts with integrity re-analysis, and seven layers structure through the mapping model extrpulation contrasts with integrity re-analysis. Any layer SSHLPS among 1-8 can be calculated with much accuracy. Amount of calculation can also be reduced if it is appfied into the same topological structure, with reduced distortion and assured precision. 展开更多
关键词 Plane model - Space model Artificial neural networks mapping model Optimum design
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MODEL SHIFT AND STRANGE ATTRACTOR ON MBIUS STRIP
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作者 陈芳跃 陈凤娟 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2003年第7期845-852,共8页
A new model shift mapping was given in bilateral symbol space. It is topologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, a model was constructed correspondent to the model shift map... A new model shift mapping was given in bilateral symbol space. It is topologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, a model was constructed correspondent to the model shift mapping, i.e., a class of mapping on Mbius strip was given. Its attractors' structure and dynamical behaviour were described. 展开更多
关键词 model shift mapping Mbius strip CHAOS strange attractor
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Dose-Injury Relation as a Model for Uncertainty Propagation from Input Dose to Target Dose 被引量:1
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作者 Hongyun Wang Wesley A. Burgei Hong Zhou 《American Journal of Operations Research》 2018年第5期360-385,共26页
We study a general framework for assessing the injury probability corresponding to an input dose quantity. In many applications, the true value of input dose may not be directly measurable. Instead, the input dose is ... We study a general framework for assessing the injury probability corresponding to an input dose quantity. In many applications, the true value of input dose may not be directly measurable. Instead, the input dose is estimated from measurable/controllable quantities via numerical simulations using assumed representative parameter values. We aim at developing a simple modeling framework for accommodating all uncertainties, including the discrepancy between the estimated input dose and the true input dose. We first interpret the widely used logistic dose-injury model as the result of dose propagation uncertainty from input dose to target dose at the active site for injury where the binary outcome is completely determined by the target dose. We specify the symmetric logistic dose-injury function using two shape parameters: the median injury dose and the 10 - 90 percentile width. We relate the two shape parameters of injury function to the mean and standard deviation of the dose propagation uncertainty. We find 1) a larger total uncertainty will spread more the dose-response function, increasing the 10 - 90 percentile width and 2) a systematic over-estimate of the input dose will shift the injury probability toward the right along the estimated input dose. This framework provides a way of revising an established injury model for a particular test population to predict the injury model for a new population with different distributions of parameters that affect the dose propagation and dose estimation. In addition to modeling dose propagation uncertainty, we propose a new 3-parameter model to include the skewness of injury function. The proposed 3-parameter function form is based on shifted log-normal distribution of dose propagation uncertainty and is approximately invariant when other uncertainties are added. The proposed 3-parameter function form provides a framework for extending skewed injury model from a test population to a target population in application. 展开更多
关键词 DOSE INJURY RELATION DOSE Propagation Uncertainty MEDIAN INJURY DOSE 10 - 90 Percentile Width SKEWNESS mapping INJURY model from One Population to Another
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Flood Maps and Bank Shifting of Dharla River in Bangladesh
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作者 Indira Bose Umme Kulsum Navera 《Journal of Geoscience and Environment Protection》 2017年第9期109-122,共14页
Bangladesh is prone to severe flooding as being located at the confluence of three mighty rivers named the Ganges, Brahmaputra, and Meghna. As a consequence, river flooding and erosion are common natural disasters tha... Bangladesh is prone to severe flooding as being located at the confluence of three mighty rivers named the Ganges, Brahmaputra, and Meghna. As a consequence, river flooding and erosion are common natural disasters that severely affect the landscape, lives and economy of the country. Dharla River, one of the trans-boundary rivers originated in the Himalayas, along with Brahmaputra River has a great influence on the recurring floods and erosion in north-western Bangladesh. Almost in every year, excessive erosion and embankment damages caused by Dharla render a thousand of people homeless with massive loss of crops and poultries. As per the environmentalists, this is a matter of huge concern as development of accurate flood maps and erosion prediction for Dharla River has been very challenging. In this study, the flood map and Dharla River bank shifting study have been developed by using HEC-RAS 4.1.0 hydrodynamic model and Landsat satellite images. In addition, the HEC-GeoRAS was used to establish the river reach for HEC-RAS. The calibration and validation have been performed using the observed and simulated water levels for the years of 2013 and 2014 respectively. The HEC-RAS flood water level output was used in HEC-GeoRAS for raster interpolation followed by overlain onto the land surface elevation of the study area. Then, the difference between water level interpolation and land elevation surfaces has been considered as a depth of inundation which is performed in Arc-Map 10.2. Flood maps have been generated for the years 2010, 2013, and 2014 for highest water level of each year. The erosion prone areas have been indicated by analyzing bank shifting of Dharla River for the years 1987, 1997, 2007, and 2017 by digitizing the satellite images in Arc-GIS 10.2. From the observation it has been found that the course of the Dharla River has been shifted vastly since 1987 to 2017 due to erosion. 展开更多
关键词 HYDRODYNAMIC modeling GIS FLOOD FLOOD mapS BANK shiftING Erosion
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应用生态位模型研究外来入侵物种生态位漂移 被引量:20
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作者 王运生 谢丙炎 +2 位作者 万方浩 肖启明 戴良英 《生态学报》 CAS CSCD 北大核心 2008年第10期4974-4981,共8页
由于基础生态位和实际生态位的改变,外来入侵物种在入侵地成功定殖、扩散后常会发生生态位漂移,而物种生态位漂移往往很难直接证明。生态位模型在假设入侵物种的生态位需求保守的前提下,以物种在其原产地的生态位需求为基础,预测其在入... 由于基础生态位和实际生态位的改变,外来入侵物种在入侵地成功定殖、扩散后常会发生生态位漂移,而物种生态位漂移往往很难直接证明。生态位模型在假设入侵物种的生态位需求保守的前提下,以物种在其原产地的生态位需求为基础,预测其在入侵地的潜在分布,通过比较预测分布与实际分布的差异可以从一定程度上得到外来入侵物种的生态位是否发生漂移的间接证据。以我国入侵杂草胜红蓟在原产地的生态位需求为基础,应用生态位模型预测其在其他地区的潜在分布。研究结果表明,生态位模型可以很好地预测胜红蓟在亚太平洋地区和非洲地区的分布,但在我国,其预测分布与实际分布存在较大差别。胜红蓟在我国预测分布主要为云南、海南、台湾部分地区,而胜红蓟入侵我国后现已广泛分布于长江以南地区,其实际分布比预测分布广泛得多,由此推测胜红蓟在入侵我国后其生态位已经产生了漂移。 展开更多
关键词 胜红蓟 生态位漂移 生态位模型 适生图
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一类描述混沌映射的符号动力系统 被引量:12
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作者 李明军 李开泰 《高校应用数学学报(A辑)》 CSCD 北大核心 1999年第2期125-129,共5页
本文定义了符号空间上的拟移位映射,并用该类映射描述了Cantor集及平面Cantor集上的混沌映射.本文结果可看作Smale马蹄模型的简化.
关键词 符号动力系统 SMALE马蹄 拟移位映射 混沌映射
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符号空间的拟移位和Mbius带上的奇怪吸引子 被引量:7
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作者 陈芳跃 陈凤娟 《应用数学和力学》 CSCD 北大核心 2003年第7期747-754,共8页
 给出了双边符号空间上的一种新的拟移位映射,得到了它与传统的移位映射拓扑共轭· 类似Smale马蹄,对这种拟移位映射给出了一个模型,即在M
关键词 拟移位映射 Moebius带 混沌 奇怪吸引子
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双边符号空间上的左拟移位映射 被引量:3
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作者 王经民 《西北林学院学报》 CSCD 北大核心 2000年第4期105-108,共4页
本文证明了双边符号空间上的左拟移位映射在 Li-
关键词 双边符号空间 拟移位映射 强紊动
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双边拟移位映射的混沌性 被引量:1
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作者 陈凤娟 《浙江师范大学学报(自然科学版)》 CAS 2002年第3期221-223,共3页
在双边符号空间上给出了一类新的拟移位映射 ,得到该映射具有连续性和Li Yorke意义下的混沌性 ,并用较为简洁的方法证明了该类映射的上述
关键词 双边拟移位映射 混沌映射 双边符号空间 连续性 Li—Yorke混沌 拓扑共轭
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双边符号空间上的一类拟移位映射 被引量:1
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作者 陈凤娟 《浙江师范大学学报(自然科学版)》 CAS 2004年第1期1-5,共5页
给出了双边符号空间上的拟移位映射,证明它与通常的移位映射σ拓扑共轭,并且用它刻划了平面上含有Smale马蹄的映射.
关键词 SMALE马蹄 拟移位映射 拓扑共轭 符号动力系统
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一类描述五分Cantor集的拟移位映射
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作者 徐园芬 戴振祥 《浙江师范大学学报(自然科学版)》 CAS 2010年第4期387-391,共5页
在单边符号空间上构造了一类拟移位映射,证明了它与通常的移位映射σ拓扑半共轭,得到这类映射具有连续性和在Li-Yorke意义下的混沌性,并用拟移位映射描述了五分Cantor集的混沌映射.
关键词 单边符号空间 拟移位映射 五分Cantor集 LI-YORKE混沌
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简化的Smale马蹄模型
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作者 陈燕芬 《南阳师范学院学报》 CAS 2006年第12期27-28,32,共3页
定义了符号空间上的拟移位映射,并用该类映射描述了平面Cantor集上的混沌映射,给出此映射的一些性质和Smale马蹄模型的简化形式.
关键词 符号动力系统 SMALE马蹄 拟移位映射 平面Cantor集
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基于像素交叉循环移位与混沌映射的图像加密
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作者 赵铎 《系统仿真技术》 2018年第1期62-67,共6页
提出基于像素交叉循环移位与自控混沌映射的图像加密算法。迭代均布Logistic映射,输出密钥;根据明文像素与密钥设计像素交叉循环移位机制,并对明文像素进行高度置乱;利用均布Logistic映射生成Tent映射的初始条件,再通过像素扩散机制的... 提出基于像素交叉循环移位与自控混沌映射的图像加密算法。迭代均布Logistic映射,输出密钥;根据明文像素与密钥设计像素交叉循环移位机制,并对明文像素进行高度置乱;利用均布Logistic映射生成Tent映射的初始条件,再通过像素扩散机制的定义完成像素加密;引入重力模型来构造深度扩散机制,然后最大化密文的统一平均变化强度,从而提高算法的抗攻击能力。结果表明:与当前图像加密技术相比,所提算法具有更高的安全性以及更强的抗攻击能力。 展开更多
关键词 图像加密 像素交叉循环移位 自控混沌映射 像素扩散机制 重力模型 深度扩散
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符号动力系统的拟移位及Smale马蹄模型表示
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作者 李二林 陈芳跃 胥海云 《杭州电子科技大学学报(自然科学版)》 2017年第4期75-78,共4页
给出了双边符号序列空间上的一种拟移位映射,通过构造一个同胚映射,证明这种拟移位映射与传统的移位映射拓扑共轭,同时,这个拟移位仍可由Smale马蹄模型来表示.
关键词 双边符号空间 SMALE马蹄 拟移位映射 Cantor三分集 拓扑共轭
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符号空间上的左拟移位映射
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作者 庄云标 《台州学院学报》 2003年第6期21-22,39,共3页
给出了双边符号空间上的一新的拟移位映射 。
关键词 双边符号空间 拟移位映射 紊动
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拟移位映射与移位映射拓扑共轭
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作者 代莉 《怀化学院学报》 2009年第2期36-39,共4页
研究了文献[1]中的模映射,证明其拓扑熵为0,另外利用该映射证明了拟移位映射和移位映射拓扑共轭,从而揭示出拟移位映射是移位映射的一个重要的拓扑共轭系统.
关键词 模映射 移位映射 拟移位映射 帐篷映射 拓扑熵
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火焰山地区精细地震勘探方法研究
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作者 任青春 郭金盾 +2 位作者 王凌云 汪超 张琪 《吐哈油气》 2009年第2期104-106,120,共4页
吐哈盆地火焰山地区,其逆掩断裂带应用原处理得到的T0剖面和速度谱资料做出的构造图误差大,与实际钻井结果相去甚远。在山前平缓区域,大部分地震资料也受到了火焰山影响,加上低降速带异常等问题,构造圈闭的位置难以确定。整个火焰山地... 吐哈盆地火焰山地区,其逆掩断裂带应用原处理得到的T0剖面和速度谱资料做出的构造图误差大,与实际钻井结果相去甚远。在山前平缓区域,大部分地震资料也受到了火焰山影响,加上低降速带异常等问题,构造圈闭的位置难以确定。整个火焰山地区勘探精度较低。为了提高该区勘探精度,在该区开发应用了动态时移静校正技术、模型模拟速度分析与成图技术,使用新的处理解释一体化思路对该区域进行综合研究。消除了常规地震勘探方法中存在理论误差和方法误差,使处理和解释工作紧密结合。提高了地震资料处理精度,从而提高了该区勘探精度。 展开更多
关键词 勘探精度 动态时移静校正 模型模拟速度分析与成图 处理解释一体化
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一类描述Sierpinski(谢尔宾斯基)垫的拟移位映射 被引量:1
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作者 王书颖 范钦杰 《吉林师范大学学报(自然科学版)》 2007年第4期49-51,共3页
本文构造了一类拟移位映射τ1,并证明了此移位映射与符号空间上通常的移位映射σ拓扑半共轭,进而证明了τ1是Li—Yorke混沌非Devaney意义混沌的结论,并且用τ1描述了Sierpinski(谢尔宾斯基)垫.
关键词 拟移位映射 拓扑半共轭 LI-YORKE混沌 Sierpinski(谢尔宾斯基)垫
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拓扑熵为log 1.618的符号动力系统
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作者 王肖义 李明军 《数学学报(中文版)》 SCIE CSCD 北大核心 2009年第5期891-896,共6页
拟移位映射是符号空间上一类特殊的混沌映射,被广泛关注。本文证明:拟移位映射和移位映射拓扑共轭,从而揭示出拟移位映射是移位映射的一个重要的拓扑共轭系统。同时构造了一类拓扑熵为log1.618的符号动力系统,且该系统是在Devaney意义... 拟移位映射是符号空间上一类特殊的混沌映射,被广泛关注。本文证明:拟移位映射和移位映射拓扑共轭,从而揭示出拟移位映射是移位映射的一个重要的拓扑共轭系统。同时构造了一类拓扑熵为log1.618的符号动力系统,且该系统是在Devaney意义下混沌的。另外,得到了一类以整个符号空间为极小集的非混沌动力系统。 展开更多
关键词 拟移位映射 帐篷映射 拓扑熵
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