检索结果-内蒙古大学图书馆

International Symposium on Computer Science and Computational Technology

作者： Liu, Xiaosheng Chen, Zhihui JUST Sch Architectural & Surveying Engn Ganzhou Jiangxi Peoples R China

ISBN: (纸本)9780769534985

This paper presents a new noise detection method, in which set eight differential operators, the every pixel gradient is obtained by the eight differential operator and image for convolution. Then an arithmetical mean, which comes from the convolution, is used as final comprehensive assessment indicators. The experimental results show that the method can reflect the impact of different types of noise on the image, and detect the value range of different types of noise.

关键词： gradient gradient function noise detection differe-ntial operators

来源：评论

学校读者我要写书评

暂无评论

Exploratory assessment of treatment-dependent random-effects distribution using gradient functions

引用

STATISTICS IN MEDICINE 2021年第2期40卷 226-239页

作者： Imai, Takumi Tanaka, Shiro Kawakami, Koji Osaka City Univ Grad Sch Med Dept Med Stat Osaka Japan Kyoto Univ Grad Sch Med Dept Clin Biostat Kyoto Japan Kyoto Univ Grad Sch Med & Publ Hlth Dept Pharmacoepidemiol Kyoto Japan

In analyzing repeated measurements from randomized controlled trials with mixed-effects models, it is important to carefully examine the conventional normality assumption regarding the random-effects distribution and its dependence on treatment allocation in order to avoid biased estimation and correctly interpret the estimated random-effects distribution. In this article, we propose the use of a gradient function method in modeling with the different random-effects distributions depending on the treatment allocation. This method can be effective for considering in advance whether a proper fit requires a model that allows dependence of the random-effects distribution on covariates, or for finding the subpopulations in the random effects.

关键词： gradient function random‐ effects distribution RCT repeated measurements

来源：评论

学校读者我要写书评

暂无评论

Multiple estimates of soil structure at a vertical strong motion array: Understanding uncertainties from different shear wave velocity profiles

引用

ENGINEERING GEOLOGY 2015年 192卷 1-18页

作者： Raptakis, Dimitrios Makra, Konstantia Aristotle Univ Thessaloniki Dept Civil Engn GR-54006 Thessaloniki Greece Inst Engn Seismol & Earthquake Engn EPPO Thessaloniki Greece

We present a detailed study of investigation of various shear wave velocity, Vs, profiles at the TST site of the Euroseistest test-site. We benefit from the availability of 62 Vs models derived from earthquake records, conventional seismic prospecting, and seismic noise array measurements. Five groups of models provided from many different non-invasive and invasive methods (seismic interferometry, stress-strain analysis, annealing simulation, surface wave inversion, cross-hole and down-hole tests, and seismic noise array measurements) lead to averaged Vs profiles. The estimate of Vs models that we obtain differs depending on the technique used. In such cases, it becomes clear that, it is better to understand the differences and not simply compute an average. The percentage of the observed disparity with respect to the average reference model albeit is small, becomes significant at certain depths and is associated with the existence of strong vertical discontinuities, thus introducing an uncertainty on the interface definition between the main formations. On the other hand, the use of Vs profiles in ground simulation studies (especially 2D or 3D) usually implies the need to represent them as gradient functions. Testing representative generalized power law functions, we found that they fail to predict reliably the Vs model for the total thickness of sediments. To overcome this, a third order polynomial function is proposed. Finally, we test the sensitivity of average Vs, index widely used in soil categorization and site amplification studies and find that all Vs models, either measured or proposed, are equivalent in terms of Vs, vanishing any discrimination between layering as well as models. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Vertical strong motion array Shear walk velocity Earthquake data analysis Seismic prospecting Seismic noise array gradient function

来源：评论

学校读者我要写书评

暂无评论

Defective point data reconstruction based on improved process of morphological operations

引用

Science China(Technological Sciences) 2011年第12期54卷 3166-3179页

作者： YIN ZhouPing MO Kun XIONG YouLun State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan 430074 China

In industry,the defective point data often make most surface reconstruction methods suffer from inherent problems that some specific aided information is difficult to obtain. To solve the problem,a novel implicit reconstruction method without any such information is proposed. This approach extends morphological operations into 3D space and provides an improved procedure to construct off-set gradient functions for indirect approximation. By this method,the dual relative functions guarantee a minimal crust surrounding the point data. They can generate a smooth and watertight resulting surface,filling holes and merging overlapping samples reasonably. Compared with other existing methods,the proposed method is better suited to handle defective point clouds in a convenient and efficient manner. The feasibility and effectiveness of the method are demonstrated through a series of practical examples.

关键词： surface reconstruction morphology operation weighted vector median fdter gradient function off-set surface

来源：评论

学校读者我要写书评

暂无评论

Controllability of mesoscopic surface roughness of sputtered Al and Al-N films

引用

MATERIALS TRANSACTIONS 2005年第12期46卷 3037-3043页

作者： Ishiguro, T Miyamura, K Nagaoka Univ Technol Dept Elect Engn Nagaoka Niigata 9402188 Japan

There is a concept that the surface roughness is the structure-type of the optical gradient function because the material volume fraction gradually changes along the surface normal from the vacuum (or air) to the material. In this sense, the controlling the surface undulations corresponds to the controlling the gradient-profile. Sputtered Al film, AlN film, and incompletely-nitrided Al film (Al-N film) has been investigated from the view point of forming the mesoscopic scaled surface roughness because it can be applied to, e.g., the solar absorption coating, the solar cell and/or the diffusive coloring. The surface structures have been characterized and the growth condition dependence, such as the degree of nitriding which is controlled by changing mixing ratio of N-2 and Ar sputtering gases, the film thickness (d(f)), and the substrate temperature (T-sub). are systematically investigated. The following controllable factors about surface Structure are confirmed. The characteristic of the form of protuberances on the surface depends on the degree of nitriding. The height and the width of the protuberances can be controlled by or and/or T-sub.

关键词： surface roughness sputtered aluminum film AlN film aluminum-nitrogen film gradient function thin film

来源：评论

学校读者我要写书评

暂无评论

Diagnosing Misspecification of the Random-Effects Distribution in Mixed Models

引用

BIOMETRICS 2017年第1期73卷 63-71页

作者： Drikvandi, Reza Verbeke, Geert Molenberghs, Geert Katholieke Univ Leuven I BioStat Leuven Belgium Imperial Coll London Dept Math London England Univ Hasselt I BioStat Hasselt Belgium

It is traditionally assumed that the random effects in mixed models follow a multivariate normal distribution, making likelihood-based inferences more feasible theoretically and computationally. However, this assumption does not necessarily hold in practice which may lead to biased and unreliable results. We introduce a novel diagnostic test based on the so-called gradient function proposed by Verbeke and Molenberghs (2013) to assess the random-effects distribution. We establish asymptotic properties of our test and show that, under a correctly specified model, the proposed test statistic converges to a weighted sum of independent chi-squared random variables each with one degree of freedom. The weights, which are eigenvalues of a square matrix, can be easily calculated. We also develop a parametric bootstrap algorithm for small samples. Our strategy can be used to check the adequacy of any distribution for random effects in a wide class of mixed models, including linear mixed models, generalized linear mixed models, and non-linear mixed models, with univariate as well as multivariate random effects. Both asymptotic and bootstrap proposals are evaluated via simulations and a real data analysis of a randomized multicenter study on toenail dermatophyte onychomycosis.

关键词： Asymptotic distribution Eigenvalues gradient function Longitudinal data Parametric bootstrap Random effects

来源：评论

学校读者我要写书评

暂无评论

High speed and silicon-saving adaptive tuning system for high frequency Gm-C filters

引用

ANALOG INTEGRATED CIRCUITS AND SIGNAL PROCESSING 2010年第1期65卷 97-103页

作者： Ezzati, Nematollah Abdollahzadeh, Sohrab Urmia Univ Technol Dept Elect Engn Orumiyeh Iran Urmia Univ Technol Dept Ind Engn Orumiyeh Iran

In this paper, a novel adaptive tuning system used in Gm-C continuous time (CT) filters has been presented. The novelty of this method is the generation of quasi-gradient functions for the adaptive algorithm. By this method we have implemented the fully adaptive tuning algorithm on chip, and received more than 95% precision for the all characteristics of Gm-C filter. All the circuit level simulations and prototype fabrication have been done using 0.6 mu CMOS technology of AMS.

关键词： Gm-C filter Tuning system Adaptive tuning gradient function

来源：评论

学校读者我要写书评

暂无评论

Optimizing gradient Methods for IoT Applications

引用

IEEE INTERNET OF THINGS JOURNAL 2022年第15期9卷 13694-13704页

作者： Hosseini, Eghbal Reinhardt, Line Rawat, Danda B. Roskilde Univ Dept People & Technol DK-4000 Roskilde Denmark Howard Univ Dept Elect Engn & Comp Sci Washington DC 20059 USA

Solving linear programming (LP) and nonlinear programming (NLP) problems is momentous because of their wide applications in real-life problems. There is no unified way to find the global optimum for NLPs. But on the other hand, the simplex algorithm, as the dominating methodology for LPs for several decades moves only on the boundary (vertices) and ignores the vast majority of the feasible region in the process of searching. In this article, we study two gradient-based methodologies that explore the whole feasible region, which guarantee faster convergence rates for both LP and NLP optimization problems including IoT problems such as Software-Defined Internet of Vehicles (SDIoV) and vehicular ad hoc networks (VANETs). The gradient-simplex algorithm (GSA) for LPs, which moves inside the feasible region in the gradient direction at first to reduce the search space and then explores the reduced boundary to find an optimal solution. The evolutionary-gradient algorithm (EGA), on the other hand, is for NLPs and uses an evolutionary population to estimate gradients by evolving to find better solutions in steps. Based on extensive simulations, the obtained numerical results show that both approaches provide efficient solutions and outperform the state-of-the-art methods on optimization problems with large feasible spaces. Comparative results of applying the GSA on SDIoV and VANETs with different sizes are included.

关键词： Statistics Sociology Internet of Things Approximation algorithms Software algorithms Linear programming Optimization Evolutionary population feasible region gradient function Internet of Things simplex algorithm

来源：评论

学校读者我要写书评

暂无评论

Efficient calculation of the NPMLE of a mixing distribution for mixtures of exponentials

引用

COMPUTATIONAL STATISTICS & DATA ANALYSIS 2006年第5期50卷 1248-1271页

作者： Seidel, W Sever, K Sevcíková, H Univ Hamburg Inst Stat & Quantitat Okonom D-22039 Hamburg Germany Univ Washington Dept Stat Seattle WA 98195 USA

A crucial step in all gradient-based algorithms for calculating the nonparametric maximum likelihood estimator in mixture models is the global maximization of the gradient function. For example, in mixtures of exponentials, the methods usually proposed fail. Based on a discretization which is adapted to the data points, a method for maximizing the gradient is suggested. The method is implemented in different gradient-based algorithms;a comparison shows that on mixtures of exponentials, the ISDM algorithm introduced by Lesperance and Kalbfleisch is much faster than its competitors. (C) 2004 Elsevier B.V. All rights reserved.

关键词： EM algorithm global maximization gradient function intra-simplex direction method maximum likelihood estimation mixture models vertex direction method vertex exchange method

来源：评论

学校读者我要写书评

暂无评论

Robust inference for finite poisson mixtures

引用

JOURNAL OF STATISTICAL PLANNING AND INFERENCE 2001年第1-2期93卷 93-115页

作者： Karlis, D Xekalaki, E Athens Univ Econ & Business Dept Stat Athens 10434 Greece

Inference for mixture models based on likelihood estimates suffers from lack of robustness. The presence of a few spurious observations may lead to incorrect decisions. In this paper we consider robust alternatives to the likelihood inference for finite Poisson mixtures based on the minimum Hellinger distance estimates. A new test, the Hellinger deviance test, is proposed for testing the Poisson hypothesis versus a Poisson mixture hypothesis. Moreover, diagnostics based on the Hellinger gradient function in order to examine for the presence of a mixture are described. Semiparametric estimation is also discussed. All these inferential procedures combine both efficiency when the model is correct and robustness when the model is incorrect, and make the minimum Hellinger distance methodology a competitive alternative to the maximum likelihood methodology. (C) 2001 Elsevier Science B.V. All rights reserved. MSG: 62F35;62G35.

关键词： gradient function influence Hellinger deviance test robustness likelihood ratio test Hellinger gradient function semiparametric estimation

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：