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宽函数的布尔匹配及其在FPGA重综合中的应用
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作者 张峰 王作建 +2 位作者 吴洋 于芳 刘忠立 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2013年第5期34-42,共9页
当前大多数商用现场可编程门阵列(FPGA)可配置逻辑块结构在查找表(LUT)的基础上增加了很多辅助逻辑资源,而传统的LUT基工艺映射算法无法充分利用这些资源.为此,文中提出一种基于香农展开式和不相交支持集分解算法的布尔匹配方法,并将其... 当前大多数商用现场可编程门阵列(FPGA)可配置逻辑块结构在查找表(LUT)的基础上增加了很多辅助逻辑资源,而传统的LUT基工艺映射算法无法充分利用这些资源.为此,文中提出一种基于香农展开式和不相交支持集分解算法的布尔匹配方法,并将其应用于工艺映射后的重综合.使用该方法对工艺映射后网表中的宽函数进行布尔匹配,使其在目标FPGA结构上重新实现,从而达到充分利用所有逻辑资源和减少LUT数的目的.实验结果表明,该方法能在不增加电路关键路径延时的基础上,对学术界综合工具ABC工艺映射之后的4-LUT和6-LUT网表分别节省7.9%和7.8%的面积开销. 展开更多
关键词 电子设计自动化 现场可编程门阵列 布尔匹配 宽函数 重综合 可配置逻辑块 查找表
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渐近波形估计应用于无限大导体平面上凹槽散射场宽角度方向性函数的快速获取 被引量:2
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作者 童创明 周后型 洪伟 《微波学报》 CSCD 北大核心 2001年第1期7-12,共6页
本文基于渐近波形估计 (AWE)技术和矩量法 (MOM)快速预测无限大导体平面上任意形状凹槽的散射场方向性函数。用矩量法求解得到给定方向入射波照射下凹槽口径磁流 ,用AWE技术得到任意方向入射波照射下口径磁流 ,进而计算出散射场的方向... 本文基于渐近波形估计 (AWE)技术和矩量法 (MOM)快速预测无限大导体平面上任意形状凹槽的散射场方向性函数。用矩量法求解得到给定方向入射波照射下凹槽口径磁流 ,用AWE技术得到任意方向入射波照射下口径磁流 ,进而计算出散射场的方向性函数。计算结果表明AWE能逼近 MOM计算结果 。 展开更多
关键词 渐近波形估计技术 散射场 凹槽 角度方向性函数
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水果品质检测中的模糊阈值分割方法 被引量:7
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作者 沈明霞 李秀智 姬长英 《农业机械学报》 EI CAS CSCD 北大核心 2003年第5期113-115,共3页
为实现利用机器视觉技术进行水果检测分级 ,对水果检测图像的分割进行了研究。依据模糊集合理论 ,提出了先验知识引导的自适应模糊阈值分割算法 。
关键词 水果 品质检测 模糊阈值 分割方法 检测图像 阈值 隶属函数 隶属函数 自动选取
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基于模糊熵的自适应多阈值图像分割方法 被引量:5
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作者 宋欢欢 李雷 《计算机技术与发展》 2014年第12期32-36,共5页
模糊技术能够很好地表达和处理不确定问题,是图像处理领域中一种非常重要的技术。基于模糊理论,文中提出了基于模糊熵的自适应多阈值分割方法。根据图像像素的概率分布,将图像行区域化,利用每个区域中像素属于前景和背景的模糊性定义隶... 模糊技术能够很好地表达和处理不确定问题,是图像处理领域中一种非常重要的技术。基于模糊理论,文中提出了基于模糊熵的自适应多阈值分割方法。根据图像像素的概率分布,将图像行区域化,利用每个区域中像素属于前景和背景的模糊性定义隶属度函数,采用一维搜索方法确定最佳的隶属度函数窗宽,计算最大模糊熵,从而找到区域最优阈值。文中对多目标、光照不均匀、存在噪声和分割不完全的图像进行实验,结果表明该方法能够很好地解决上述问题,并且较传统的基于Otsu和模糊熵的图像单阈值分割方法,效果显著提高,具有较好的适应性和实用性。 展开更多
关键词 图像分割 模糊熵 隶属度函数 多阈值图像分割
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强地震动估计和地震危险性评定 被引量:5
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作者 谢礼立 陶夏新 王国新 《东北地震研究》 2001年第1期1-8,共8页
本文介绍了近几年获取的强震记录中显示出的地震动特征 ,诸如近断裂的破裂方向性效应、上盘效应、影响地震波传播的地壳波导效应、沉积盆地的放大效应和盆地边缘效应 ;归纳了强地震动估计的三种方法 ,简要综述了经验性衰减模型、预测强... 本文介绍了近几年获取的强震记录中显示出的地震动特征 ,诸如近断裂的破裂方向性效应、上盘效应、影响地震波传播的地壳波导效应、沉积盆地的放大效应和盆地边缘效应 ;归纳了强地震动估计的三种方法 ,简要综述了经验性衰减模型、预测强地震动的随机法和宽频带格林函数法 ; 展开更多
关键词 地震危险性评定 地震动 活断层 地震波 频带格林函数 地壳波导效应
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On n-K Width of Certain Function Classes Defined by Linear Differential Operators in L_2 Space
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作者 吴嘎日迪 包那 《Chinese Quarterly Journal of Mathematics》 CSCD 1999年第4期27-31, ,共5页
Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates... Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates of the n K width d n(W M(A),L 2[0,1]) . 展开更多
关键词 linear operator smooth function class WIDTH
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On n-K Width of Certain Function Classes Defined by Linear Differential Operators in L2 Space 被引量:2
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作者 吴嘎日迪 包那 《Chinese Quarterly Journal of Mathematics》 CSCD 1999年第4期27-31,共页
Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates... Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates of the n K width d n(W M(A),L 2[0,1]) . 展开更多
关键词 linear operator smooth function class WIDTH
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Strong Consistency for the Kernal Estimates of the Random Window Width of the Density Function and its Derivatives Under Φ-Mixing Samples
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作者 樊家琨 《Chinese Quarterly Journal of Mathematics》 CSCD 1993年第3期52-56,共5页
In the paper,we study the strong uniform consistency for the kernal estimates of random window w■th of density function and its derivatives under the condition that the sequence{X_n}of the ■ are the identically Φ-m... In the paper,we study the strong uniform consistency for the kernal estimates of random window w■th of density function and its derivatives under the condition that the sequence{X_n}of the ■ are the identically Φ-mixing random variabks. 展开更多
关键词 Φ-mixing sample probability density function random window width kemal estimate strng uniform consistency
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Spectrum Allocation for Cognitive Radio Networks with Non-Deterministic Bandwidth of Spectrum Hole 被引量:1
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作者 Jie Huang Xiaoping Zeng +2 位作者 Xiaoheng Tan Xin Jian Yuan He 《China Communications》 SCIE CSCD 2017年第3期87-96,共10页
The spectrum allocation for cognitive radio networks(CRNs) has received considerable studies under the assumption that the bandwidth of spectrum holes is static. However, in practice, the bandwidth of spectrum holes i... The spectrum allocation for cognitive radio networks(CRNs) has received considerable studies under the assumption that the bandwidth of spectrum holes is static. However, in practice, the bandwidth of spectrum holes is time-varied due to primary user/secondary user(PU/SU) activity and mobility, which result in non-determinacy. This paper studies the spectrum allocation for CRNs with non-deterministic bandwidth of spectrum holes. We present a novel probability density function(PDF) through order statistics as well as its simplified form to describe the statistical properties of spectrum holes, with which a statistical spectrum allocation model based on stochastic multiple knapsack problem(MKP) is formulated for spectrum allocation with non-deterministic bandwidth of spectrum holes. To reduce the computational complexity, we transform this stochastic programming problem into a constant MKP through exploiting the properties of cumulative distribution function(CDF), which can be solved via MTHG algorithm by using auxiliary variables. Simulation results illustrate that the proposed statistical spectrum allocation algorithm can achieve better performance compared with the existing algorithms when the bandwidth of spectrum holes is time-varied. 展开更多
关键词 cognitive radio time-varied spectrum allocation non-deterministic bandwidth of spectrum holes stochastic programming
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A whiter shade of male: Color background matching as a function of size and sex in the yellow shore crab Hemigrapsus oregonensis (Dana, 1851) 被引量:1
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作者 Gregory C. JENSEN Michael S. EGNOTOVICH 《Current Zoology》 SCIE CAS CSCD 2015年第4期729-738,共10页
Juveniles of the shore crab Hemigrapsus oregonensis are highly variable in color, ranging from the typical yellowish- green of adults to pure white and myriad patterns of white mottling and other disruptive markings, ... Juveniles of the shore crab Hemigrapsus oregonensis are highly variable in color, ranging from the typical yellowish- green of adults to pure white and myriad patterns of white mottling and other disruptive markings, but large individuals with white coloration appear to be very rare. Using image analysis to quantify the relative "whiteness" of beaches, we sampled crabs from nine locations in Washington State that varied widely in their amount of shell fragments and other light-colored material. The total proportion of white individuals in the different locations was strongly correlated to the proportion of white material on the beaches, but there was a striking difference between sexes. Although white specimens of both sexes declined significantly at sizes above 10 mm carapace width, white females generally persisted throughout the entire female size range on lighter-colored beaches while white males larger than 10 mm were virtually absent from all of the sampled populations. Pure white males held on dark backgrounds in captivity remained white, as they lack the dark chromatophores in their hypoderrnis needed to change color; off-white males became darker and in some cases lightened up again when transferred back to a white background. Behavioral differences between the sexes may result in differential mortality of white individuals by visual predators [Current Zoology 61 (4) 729-738, 2015 ]. 展开更多
关键词 CAMOUFLAGE COLOR Polymorphism Disruptive patterns CRABS
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The f-width in Locally Convex Spaces
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作者 宋文华 刘国芬 郝明贤 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2003年第2期225-232,共8页
In this paper we extend the width problems in normed space to locally convex space and some results are given.
关键词 f-n-width Sx.
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Analysis of reconstructed annual precipitation from tree-rings for the past 500 years in the middle Qilian Mountain 被引量:8
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作者 TIAN QinHua ZHOU XiuJi +3 位作者 GOU XiaoHu ZHAO Ping FAN ZeXin Samuli HELAMA 《Science China Earth Sciences》 SCIE EI CAS 2012年第5期770-778,共9页
The ring-width chronology of a Juniperus przewalskii tree from the middle of the Qilian Mountain was constructed to estimate the annual precipitation (from previous August to current July) since AD 1480.The reconstruc... The ring-width chronology of a Juniperus przewalskii tree from the middle of the Qilian Mountain was constructed to estimate the annual precipitation (from previous August to current July) since AD 1480.The reconstruction showed four major alternations of drying and wetting over the past 521 years.The rainy 16th century was followed by persistent drought in the 17th century.Moreover,relatively wet conditions persisted from the 18th to the beginning of 20th century until the recurrence of a drought during the 1920s and 1930s.Based on the Empirical Mode Decomposition method,eight Intrinsic Mode Functions (IMFs) were extracted,each representing unique fluctuations of the reconstructed precipitation in the time-frequency domain.The high amplitudes of IMFs on different timescales were often consistent with the high amount of precipitation,and vice versa.The IMF of the lowest frequency indicated that the precipitation has undergone a slow increasing trend over the past 521 years.The 2-3 year and 5-8 year time-scales reflected the characteristics of inter-annual variability in precipitation relevant to regional atmospheric circulation and the El Ni?o-Southern Oscillation (ENSO),respectively.The 10-13 year scale of IMF may be associated with changing solar activity.Specifically,an amalgamation of previous and present data showed that droughts were likely to be a historically persistent feature of the Earth's climate,whereas the probability of intensified rainfall events seemed to increase during the course of the 19th and 20th centuries.These changing characteristics in precipitation indicate an unprecedented alteration of the hydrological cycle,with unknown future amplitude.Our reconstruction complements existing information on past precipitation changes in the Qilian Mountain,and provides additional low-frequency information not previously available. 展开更多
关键词 Qilian Mountain tree-ring reconstruction empirical mode decomposition multi-scale precipitation variability not previously available
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