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Seed size distributions of fleshy-fruited species are more right-skewed compared to that of dry-fruited species
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作者 Xiaoyan Hu Jinyu Zhang Bo Wang 《Plant Diversity》 2025年第3期522-525,共4页
Seed dispersal is a pivotal process in seed plant life cycle,owing to its effects on seed germination,seedling survival,population recruitment,and diversity maintenance in the entire community(Howe and Smallwood,1982;... Seed dispersal is a pivotal process in seed plant life cycle,owing to its effects on seed germination,seedling survival,population recruitment,and diversity maintenance in the entire community(Howe and Smallwood,1982;Rogers et al.,2021).There are diverse dispersal modes,such as anemochory(wind-driven dispersal),hydrochory(water-mediated dispersal),autochory(self-dispersal),and zoochory,which relies on a diverse array of animals for seed dispersal(Howe and Smallwood,1982).It is widely known that these varying dispersal modes impose selective pressures on many seed and fruit traits,especially the seed size,a key trait which is associated with multiple stages of the life cycle of plants,such as dispersal,germination,and establishment,particularly during early development(Leishman et al.,2000). 展开更多
关键词 Fruit type Intraspecific variation Seed dispersal Seed mass skewNESS
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QHF-CS: Quantum-Enhanced Heart Failure Prediction Using Quantum CNN with Optimized Feature Qubit Selection with Cuckoo Search in Skewed Clinical Data
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作者 Prasanna Kottapalle Tan Kuan Tak +2 位作者 Pravin Ramdas Kshirsagar Gopichand Ginnela Vijaya Krishna Akula 《Computers, Materials & Continua》 2025年第8期3857-3892,共36页
Heart failure prediction is crucial as cardiovascular diseases become the leading cause of death worldwide,exacerbated by the COVID-19 pandemic.Age,cholesterol,and blood pressure datasets are becoming inadequate becau... Heart failure prediction is crucial as cardiovascular diseases become the leading cause of death worldwide,exacerbated by the COVID-19 pandemic.Age,cholesterol,and blood pressure datasets are becoming inadequate because they cannot capture the complexity of emerging health indicators.These high-dimensional and heterogeneous datasets make traditional machine learning methods difficult,and Skewness and other new biomarkers and psychosocial factors bias the model’s heart health prediction across diverse patient profiles.Modern medical datasets’complexity and high dimensionality challenge traditional predictionmodels like SupportVectorMachines and Decision Trees.Quantum approaches include QSVM,QkNN,QDT,and others.These Constraints drove research.The“QHF-CS:Quantum-Enhanced Heart Failure Prediction using Quantum CNN with Optimized Feature Qubit Selection with Cuckoo Search in Skewed Clinical Data”system was developed in this research.This novel system leverages a Quantum Convolutional Neural Network(QCNN)-based quantum circuit,enhanced by meta-heuristic algorithms—Cuckoo SearchOptimization(CSO),Artificial BeeColony(ABC),and Particle SwarmOptimization(PSO)—for feature qubit selection.Among these,CSO demonstrated superior performance by consistently identifying the most optimal and least skewed feature subsets,which were then encoded into quantum states for circuit construction.By integrating advanced quantum circuit feature maps like ZZFeatureMap,RealAmplitudes,and EfficientSU2,the QHF-CS model efficiently processes complex,high-dimensional data,capturing intricate patterns that classical models overlook.The QHF-CS model improves precision,recall,F1-score,and accuracy to 0.94,0.95,0.94,and 0.94.Quantum computing could revolutionize heart failure diagnostics by improving model accuracy and computational efficiency,enabling complex healthcare diagnostic breakthroughs. 展开更多
关键词 Accuracy quantum machine learning heart failure PREDICTION cuckoo search optimization(CSO) skewed clinical data quantum convolutional circuit
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Tighter sum uncertainty relations via(α,β,γ)weighted Wigner–Yanase–Dyson skew information
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作者 Cong Xu Zhaoqi Wu Shao-Ming Fei 《Communications in Theoretical Physics》 SCIE CAS CSCD 2024年第3期91-99,共9页
We establish tighter uncertainty relations for arbitrary finite observables via(α,β,γ)weighted Wigner–Yanase–Dyson((α,β,γ)WWYD)skew information.The results are also applicable to the(α,γ)weighted Wigner–Yan... We establish tighter uncertainty relations for arbitrary finite observables via(α,β,γ)weighted Wigner–Yanase–Dyson((α,β,γ)WWYD)skew information.The results are also applicable to the(α,γ)weighted Wigner–Yanase–Dyson((α,γ)WWYD)skew information and the weighted Wigner–Yanase–Dyson(WWYD)skew information.We also present tighter lower bounds for quantum channels and unitary channels via(α,β,γ)modified weighted Wigner–Yanase–Dyson((α,β,γ)MWWYD)skew information.Detailed examples are provided to illustrate the tightness of our uncertainty relations. 展开更多
关键词 quantum channels β γ)WWYD skew information β γ)MWWYD skew information uncertainty relations
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Diophantine equations and Fermat's last theorem for multivariate(skew-)polynomials
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作者 PAN Jie JIA Yu-ming LI Fang 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2024年第1期159-173,共15页
Fermat’s Last Theorem is a famous theorem in number theory which is difficult to prove.However,it is known that the version of polynomials with one variable of Fermat’s Last Theorem over C can be proved very concisely... Fermat’s Last Theorem is a famous theorem in number theory which is difficult to prove.However,it is known that the version of polynomials with one variable of Fermat’s Last Theorem over C can be proved very concisely.The aim of this paper is to study the similar problems about Fermat’s Last Theorem for multivariate(skew)-polynomials with any characteristic. 展开更多
关键词 Fermat's last theorem polynomial ring skew polynomial ring
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Nonadditive Skew(Anti-)commuting Maps on Operator Algebras
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作者 Zhang Ting Feng Liqin Qi Xiaofei 《数学理论与应用》 2024年第3期83-93,共11页
In this paper,we first give the general forms of skew commuting maps and skew anti-commuting maps by the Peirce decomposition on a unital ring with a nontrivial idempotent,respectively,and then,as applications,we obta... In this paper,we first give the general forms of skew commuting maps and skew anti-commuting maps by the Peirce decomposition on a unital ring with a nontrivial idempotent,respectively,and then,as applications,we obtain the concrete characterizations of all nonadditive skew(anti-)commuting maps on some operator algebras. 展开更多
关键词 Commuting map skew commuting map Anti-commuting map Operator algebra
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Minor Self-conjugate and Skewpositive Semidefinite Solutions to a System of Matrix Equations over Skew Fields
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作者 姜学波 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第2期86-90,共5页
Minor self conjugate (msc) and skewpositive semidefinite (ssd) solutions to the system of matrix equations over skew fields [A mn X nn =A mn ,B sn X nn =O sn ] are considered. Necessary and su... Minor self conjugate (msc) and skewpositive semidefinite (ssd) solutions to the system of matrix equations over skew fields [A mn X nn =A mn ,B sn X nn =O sn ] are considered. Necessary and sufficient conditions for the existence of and the expressions for the msc solutions and the ssd solutions are obtained for the system. 展开更多
关键词 minor self conjugate matrix skewpositive semidefinite matrix system of matrix equations skew field the real quatrnion field
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一种新型Skew Tent映射的混沌混合优化算法 被引量:17
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作者 江善和 王其申 江巨浪 《控制理论与应用》 EI CAS CSCD 北大核心 2007年第2期269-273,共5页
针对已有的混沌优化算法几乎都是利用Logistic映射作为混沌序列发生器,而该混沌序列的概率密度函数呈两头多、中间少的切比雪夫型的分布性质,不利于搜索的效率和能力,为此,首先构造一种新型混沌映射序列发生器—Skew Tent映射并结合迭... 针对已有的混沌优化算法几乎都是利用Logistic映射作为混沌序列发生器,而该混沌序列的概率密度函数呈两头多、中间少的切比雪夫型的分布性质,不利于搜索的效率和能力,为此,首先构造一种新型混沌映射序列发生器—Skew Tent映射并结合迭代优化特点加以改进,然后分析了它的混沌特性.其次,将改进的混沌映射与Alopex启发算法相结合,充分发挥Alopex算法的快速搜索能力和混沌优化全局寻优的特性,提出一种混沌混合优化算法,提高了算法的收敛速度和有效搜索全局最优解.最后,仿真算例验证了该算法的有效性和Skew Tent混沌映射的应用前景. 展开更多
关键词 LOGISTIC映射 skew TENT映射 ALOPEX算法 混沌混合优化 全局最优
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改进分段Skew Tent映射及其在扩频通信中应用 被引量:6
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作者 王保平 李文康 +2 位作者 吴成茂 张薇 谢红梅 《红外与激光工程》 EI CSCD 北大核心 2013年第10期2772-2777,共6页
混沌序列用作扩频系统扩频码,具有码元丰富、保密性好等优点。针对传统Skew Tent映射所产生随机序列的混沌特性较弱,特别是其随机性、相关性等指标较差等不足,将Skew Tent映射进行分段对偶扩展获得一种改进分段Skew Tent映射构造方法,... 混沌序列用作扩频系统扩频码,具有码元丰富、保密性好等优点。针对传统Skew Tent映射所产生随机序列的混沌特性较弱,特别是其随机性、相关性等指标较差等不足,将Skew Tent映射进行分段对偶扩展获得一种改进分段Skew Tent映射构造方法,并将其所产生的随机序列用于构造扩频通信系统的扩频码。通过扩频通信系统仿真测试验证了改进分段Skew Tent映射相比Skew Tent映射具有更加良好的混沌特性,以及所产生随机序列作为扩频系统地址码在降低系统的误码率方面有了较大的改善。改进分段Skew Tent映射作为加密算法用于图像通信系统中,有效提高了图像信息的传输质量和安全性。混沌映射进行分段对偶扩展是一种行之有效的改进方法,混沌特性更好的迭代映射更利于扩频通信在军民领域的广泛应用。 展开更多
关键词 skewTent映射 混沌性能 扩频系统 图像加密
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Adaptive Spacecraft Attitude Tracking Controller Design Based on Similar Skew-symmetric Structure 被引量:4
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作者 刘宜成 张涛 +1 位作者 宋靖雁 梁斌 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2010年第2期227-234,共8页
This article presents an adaptive attitude tracking controller with external disturbances and unknown inertia parameters. The similar skew-symmetric structure is extended from the autonomous case to the non-autonomous... This article presents an adaptive attitude tracking controller with external disturbances and unknown inertia parameters. The similar skew-symmetric structure is extended from the autonomous case to the non-autonomous case. The non-autonomous similar skew-symmetric is chosen as the desired structure of the closed loop system for attitude controller design. Based on this structure, a novel adaptive backstepping scheme is proposed to design the attitude controller by taking full advantage of the symmetry and the positive definiteness of the inertia matrix. The attitude tracking precision is enhanced by employing the linear parameterized form of the external disturbance torques. Simulation results demonstrate the effectiveness of the proposed attitude controller. 展开更多
关键词 spacecraft attitude tracking similar skew-symmetric structure backstepping ADAPTIVE NON-AUTONOMOUS
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基于Skew-Ray追迹法的均匀准直照明TIR透镜设计 被引量:3
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作者 甄艳坤 白燕 陈恩果 《光学技术》 CAS CSCD 北大核心 2019年第6期647-652,共6页
依据LED点光源模型发光特性,以特定尺寸圆目标屏获得均匀准直照明为目标,采用Skew-Ray追迹法描述光线和设计TIR透镜,其中将透镜全反射区域进行简化处理,主要通过折射区域的双自由曲面相互配合控制光线实现照明目标。经过对透镜设计结果... 依据LED点光源模型发光特性,以特定尺寸圆目标屏获得均匀准直照明为目标,采用Skew-Ray追迹法描述光线和设计TIR透镜,其中将透镜全反射区域进行简化处理,主要通过折射区域的双自由曲面相互配合控制光线实现照明目标。经过对透镜设计结果与1mm×1mm的LED扩展光源模型的组合进行非序列光线追迹模拟,模拟结果表明在距离光源2m范围内特定尺寸目标屏所获得光能利用率至少可达到79.6%,同时目标屏在近场和远场处照明均匀度可分别达到95.9%和83.9%,若以±1°作为光线准直半角标准,目标屏准直光线百分比可分别达到88.6%和73.8%。 展开更多
关键词 非成像光学 自由曲面 skew-Ray追迹法 照明均匀度 准直光线百分比
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Scale effects on non-cavitation hydrodynamics and noise of highly-skewed propeller in wake flow 被引量:1
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作者 杨琼方 王永生 张明敏 《Journal of Southeast University(English Edition)》 EI CAS 2013年第2期162-169,共8页
Regarding the scale effects on propeller's noncavitation hydrodynamics and hydroacoustics, three similar 7bladed highly-skewed propellers in the wake flow are addressed with diameters of 250, 500 and 1 000 mm, respec... Regarding the scale effects on propeller's noncavitation hydrodynamics and hydroacoustics, three similar 7bladed highly-skewed propellers in the wake flow are addressed with diameters of 250, 500 and 1 000 mm, respectively. The discrete line-spectrum noise and its standardized spectrum level scaling law, together with the total sound pressure level are analyzed. The non-cavitation noise predictions are completed by both the frequency domain method and the time domain method. As a fluctuated noise source, the time-dependent fluctuated pressure and normal velocity distribution on propeller blades are obtained by the unsteady Reynolds-averaged Navier-Stokes ( URANS ) simulation. Results show that the pressure coefficient distribution of three propellers on the 0.7R section is nearly superposed under the same advance ratio. The periodic thrust fluctuation of three propellers can exactly reflect the tonal components of the axial passing frequency (APF) and the blade passing frequency (BPF), and the fluctuation enhancement from the small to the middle propeller at the BPF is greater than that from the middle to the big one. By the two noise prediction methods, the increment of the total sound pressure level from the small to the big propeller differs by 2.49 dB. Following the standardized scaling law, the spectrum curves of the middle and big propellers are nearly the same while significantly differing from the small one. The increment of both the line-spectrum level and the total sound pressure increases with the increase in diameter. It is suggested that the model scale of the propeller should be as large as possible in engineering to reduce the prediction error of the empirical scalin~ law and weaken the scale effects. 展开更多
关键词 highly skewed propeller non-cavitation noise scale effects frequency domain time domain
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一类半环的skew-环同余的刻画 被引量:2
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作者 徐慧 冯军庆 《纺织高校基础科学学报》 CAS 2008年第1期14-16,共3页
利用半环的满的、自共轭的闭的理想给出了加法是正则半群的半环上的skew-环同余的一种刻画.类似于环中理想和同余的对应关系理论,给出了加法正则半环的skwe-环同余和一类特殊理想的一一对应关系;另外,借助于半环的一个逆序给出了skew-... 利用半环的满的、自共轭的闭的理想给出了加法是正则半群的半环上的skew-环同余的一种刻画.类似于环中理想和同余的对应关系理论,给出了加法正则半环的skwe-环同余和一类特殊理想的一一对应关系;另外,借助于半环的一个逆序给出了skew-环同余类的一种表示. 展开更多
关键词 半环 同余 skew-环 理想
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A parametric bootstrap approach for one-way classification model with skew-normal random effects 被引量:3
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作者 YE Ren-dao XU Li-jun +1 位作者 LUO Kun JIANG Ling 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2019年第4期423-435,共13页
In this paper,several properties of one-way classification model with skew-normal random effects are obtained,such as moment generating function,density function and noncentral skew chi-square distribution,etc.Based o... In this paper,several properties of one-way classification model with skew-normal random effects are obtained,such as moment generating function,density function and noncentral skew chi-square distribution,etc.Based on the EM algorithm,we discuss the maximum likelihood(ML)estimation of unknown parameters.For testing problem of fixed effect,a parametric bootstrap(PB)approach is developed.Finally,some simulation results on the Type I error rates and powers of the PB approach are obtained,which show that the PB approach provides satisfactory performances on the Type I error rates and powers,even for small samples.For illustration,our main results are applied to a real data problem. 展开更多
关键词 PARAMETRIC BOOTSTRAP EM algorithm one-way classification model skew-NORMAL DISTRIBUTION skew CHI-SQUARE DISTRIBUTION
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基于Skewed-t分布的FIGARCH模型与VaR的度量 被引量:7
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作者 黄炎龙 《应用概率统计》 CSCD 北大核心 2012年第2期189-202,共14页
金融资产收益率序列的波动具有典型的尖峰厚尾和非对称性特征,描述这种特性需以合适的概率分布函数为基础.因此,寻求更好的概率分布函数对风险度量、VaR的计算有着十分重要的意义.有鉴于此引入Skewed-t分布度量VaR,并比较分析了RiskMetr... 金融资产收益率序列的波动具有典型的尖峰厚尾和非对称性特征,描述这种特性需以合适的概率分布函数为基础.因此,寻求更好的概率分布函数对风险度量、VaR的计算有着十分重要的意义.有鉴于此引入Skewed-t分布度量VaR,并比较分析了RiskMetrics及FIGARCH类模型度量VaR值的准确程度,本文同时分析了多头头寸和空头头寸情况下的VaR.结果表明,在两种头寸情况下,Skewed-t分布在空头和多头情形对资产厚尾特性以及非对称性的拟合效果均要比正态分布好;在两种头寸中不同的置信水平下,FIAGARCH(CHUNG)模型预测的VaR值改进了使用传统模型的精确性,高估或低估风险的程度较轻. 展开更多
关键词 VAR FIGARCH模型 skewed-t分布 动态分位数测试
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The General and Centro(Kewsy) Symmetric Solutions to a System of Matrix Equations over an Arbitrary Skew Field 被引量:3
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作者 QIN Jian-guo SONG Guang-ai 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2006年第1期66-70,共5页
Necessary and sufficient conditions are given for the existence of the general solution, the centrosymmetric solution, and the centroskewsymmetric solution to a system of linear matrix equations over an arbitrary skew... Necessary and sufficient conditions are given for the existence of the general solution, the centrosymmetric solution, and the centroskewsymmetric solution to a system of linear matrix equations over an arbitrary skew field. The representations of such the solutions of the system are also derived. 展开更多
关键词 system of matrix equations inner inverse of a matrix reflexive inverse of a matrix centro skew symmetric matrix skew field
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A skew–normal mixture of joint location, scale and skewness models 被引量:1
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作者 LI Hui-qiong WU Liu-cang YI Jie-yi 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2016年第3期283-295,共13页
Normal mixture regression models are one of the most important statistical data analysis tools in a heterogeneous population. When the data set under consideration involves asymmetric outcomes, in the last two decades... Normal mixture regression models are one of the most important statistical data analysis tools in a heterogeneous population. When the data set under consideration involves asymmetric outcomes, in the last two decades, the skew normal distribution has been shown beneficial in dealing with asymmetric data in various theoretic and applied problems. In this paper, we propose and study a novel class of models: a skew-normal mixture of joint location, scale and skewness models to analyze the heteroscedastic skew-normal data coming from a heterogeneous population. The issues of maximum likelihood estimation are addressed. In particular, an Expectation-Maximization (EM) algorithm for estimating the model parameters is developed. Properties of the estimators of the regression coefficients are evaluated through Monte Carlo experiments. Results from the analysis of a real data set from the Body Mass Index (BMI) data are presented. 展开更多
关键词 mixture regression models mixture of joint location scale and skewness models EM algorithm maximum likelihood estimation skew-normal mixtures
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一类上三角矩阵环的Skew Armendariz性质 被引量:1
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作者 王文康 《西北师范大学学报(自然科学版)》 CAS 2006年第1期20-23,共4页
设α是环R的一个自同态.若R是-αrigid环,则R上的上三角矩阵环的子环Wn既是-α-skew Armendariz环又是Armendariz环.
关键词 α-skew ARMENDARIZ环 α—rigid环 ARMENDARIZ环
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On Skew Strongly Reversible Rings Relative to a Monoid 被引量:1
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作者 Zhaiming PENG Qinqin GU Liang ZHAO 《Journal of Mathematical Research with Applications》 CSCD 2016年第1期43-50,共8页
For a monoid M, we introduce the concept of skew strongly M-reversible rings which is a generalization of strongly M-reversible rings, and investigate their properties. It is shown that if G is a finitely generated Ab... For a monoid M, we introduce the concept of skew strongly M-reversible rings which is a generalization of strongly M-reversible rings, and investigate their properties. It is shown that if G is a finitely generated Abelian group, then G is torsion-free if and only if there exists a ring R with 丨R丨 ≥ 2 such that R is skew strongly G-reversible. Moreover, we prove that if R is a right Ore ring with classical right quotient ring Q, then R is skew strongly M-reversible if and only if Q is skew strongly M-reversible. 展开更多
关键词 reversible rings skew strongly M-reversible rings skew monoid rings
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基于Skewness纹理的北京城市化区域提取
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作者 李熙 关泽群 沈体雁 《安徽农业科学》 CAS 北大核心 2008年第17期7407-7409,7412,共4页
北京地区部分农作物和城市化区域的光谱属性接近,仅仅利用光谱信息无法有效地提取北京的城市化区域。提出了利用Skewness纹理区分农作物和城市化区域,结合光谱和高程信息可以有效提取城市化区域。经过大量的样本检验表明,引入Skewness... 北京地区部分农作物和城市化区域的光谱属性接近,仅仅利用光谱信息无法有效地提取北京的城市化区域。提出了利用Skewness纹理区分农作物和城市化区域,结合光谱和高程信息可以有效提取城市化区域。经过大量的样本检验表明,引入Skewness特征能够大幅度提高分类精度。 展开更多
关键词 ETM+ 遥感 纹理 建成区 skewNESS
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Joint modelling of location and scale parameters of the skew-normal distribution 被引量:2
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作者 LI Hui-qiong WU Liu-cang 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2014年第3期265-272,共8页
Joint location and scale models of the skew-normal distribution provide useful ex- tension for joint mean and variance models of the normal distribution when the data set under consideration involves asymmetric outcom... Joint location and scale models of the skew-normal distribution provide useful ex- tension for joint mean and variance models of the normal distribution when the data set under consideration involves asymmetric outcomes. This paper focuses on the maximum likelihood estimation of joint location and scale models of the skew-normal distribution. The proposed procedure can simultaneously estimate parameters in the location model and the scale model. Simulation studies and a real example are used to illustrate the proposed methodologies. 展开更多
关键词 joint mean and variance models of the normal distribution joint location and scale models ofthe skew-normal distribution maximum likelihood estimators skew-normal distribution.
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