检索结果-南通市图书馆

interval Estimation for Aggregate Queries on Incomplete Data

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2019年第6期34卷 1203-1216页

作者： An-Zhen Zhang Jian-Zhong Li Hong Gao School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China

Incomplete data has been a longstanding issue in the database community, and the subject is yet poorly handled by both theories and practices. One common way to cope with missing values is to complete their imputation (filling in) as a preprocessing step before analyses. Unfortunately, not a single imputation method could impute all missing values correctly in all cases. Users could hardly trust the query result on such complete data without any confidence guarantee. In this paper, we propose to directly estimate the aggregate query result on incomplete data, rather than to impute the missing values. An interval estimation, composed of the upper and the lower bound of aggregate query results among all possible interpretations of missing values, is presented to the end users. The ground-truth aggregate result is guaranteed to be among the interval. We believe that decision support applications could benefit significantly from the estimation, since they can tolerate inexact answers, as long as there are clearly defined semantics and guarantees associated with the results. Our main techniques are parameter-free and do not assume prior knowledge about the distribution and missingness mechanisms. Experimental results are consistent with the theoretical results and suggest that the estimation is invaluable to better assess the results of aggregate queries on incomplete data.

关键词： incomplete data aggregate query interval estimation data quality

interval interpolating wavelets with robust boundary filters

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2000年第3期43卷 287-296页

作者：水鹏朗保铮 State Key Laboratory for Radar Signal Processing Xidian University Xi'an 710071 China

This paper studies the mathematical mechanism of the generalized interpolating filters and gives the corresponding parametric representations. On the basis of the parametric representations, a novel criterion and algorithm are proposed to design interval interpolating wavelets with robust boundary filters. Furthermore, some examples are designed and their performances in data compression are investigated. Both the theoretical analysis and the experimental results show that such an interval interpolating wavelet can effectively suppress the boundary effect.

关键词： generalized interpolating filter interval interpolating wavelet boundary effect robustness.

interval grey number sequence prediction by using non-homogenous exponential discrete grey forecasting model

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2015年第1期26卷 96-102页

作者： Naiming Xie Sifeng Liu College of Economics and Management Nanjing University of Aeronautics and Astronautics Institute of Grey System Studies Nanjing University of Aeronautics and Astronautics

This paper aims to study a new grey prediction approach and its solution for forecasting the main system variable whose accurate value could not be collected while the potential value set could be defined. Based on the traditional nonhomogenous discrete grey forecasting model（NDGM）, the interval grey number and its algebra operations are redefined and combined with the NDGM model to construct a new interval grey number sequence prediction approach. The solving principle of the model is analyzed, the new accuracy evaluation indices, i.e. mean absolute percentage error of mean value sequence（MAPEM） and mean percent of interval sequence simulating value set covered（MPSVSC）, are defined and, the procedure of the interval grey number sequence based the NDGM（IG-NDGM） is given out. Finally, a numerical case is used to test the modelling accuracy of the proposed model. Results show that the proposed approach could solve the interval grey number sequence prediction problem and it is much better than the traditional DGM（1,1） model and GM（1,1） model.

关键词： grey number grey system theory interval discrete grey forecasting model non-homogeneous exponential sequence

Effect of the interval between two shocks on ejecta formation from the grooved aluminum surface

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第3期33卷 147-159页

作者： Mingyang Xu Jianli Shao Weidong Song Enling Tang School of Equipment Engineering Shenyang Ligong UniversityShenyang 110159China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

This work focuses on the effect of the interval between two shocks on the ejecta formation from the grooved aluminum(Al_(1100))surface by using smoothed particle hydrodynamics numerical *** unsupported shocks are obtained by the plate-impact between sample and two flyers at interval,with a peak pressure of approximately 30 GPa for each *** the shock interval varies from 2.11 to 7.67 times the groove depth,the bubble velocity reduces to a constant,and the micro jetting factor R_(J) from spike to bubble exhibits a non-monotonic change that decreases initially and then *** a shock interval of 3.6 times the groove depth,micro jetting factor R_(J) from spike to bubble reaches its minimum value of approximately ***,the micro jetting factor R_(F) from spike to free surface decreases linearly at first,and stabilizes around 0.25 once the shock interval surpasses 4.18 times the groove *** the shock interval is less than 4.18 times the groove depth,the unloading wave generated by the breakout of the first shock wave is superimpose with the unloading part of the second shock wave to form a large tensile area.

关键词： Ejecta Microjet Two shocks interval Smoothed particle hydrodynamics

Parameter Optimization of interval Type-2 Fuzzy Neural Networks Based on PSO and BBBC Methods

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 247-257页

作者： Jiajun Wang Tufan Kumbasar the School of Automation Hangzhou Dianzi University IEEE the Control and Automation Engineering Department Faculty of Electrical and Electronics EngineeringIstanbul Technical University

interval type-2 fuzzy neural networks(IT2FNNs)can be seen as the hybridization of interval type-2 fuzzy systems(IT2FSs) and neural networks(NNs). Thus, they naturally inherit the merits of both IT2 FSs and NNs. Although IT2 FNNs have more advantages in processing uncertain, incomplete, or imprecise information compared to their type-1 counterparts, a large number of parameters need to be tuned in the IT2 FNNs,which increases the difficulties of their design. In this paper,big bang-big crunch(BBBC) optimization and particle swarm optimization(PSO) are applied in the parameter optimization for Takagi-Sugeno-Kang(TSK) type IT2 FNNs. The employment of the BBBC and PSO strategies can eliminate the need of backpropagation computation. The computing problem is converted to a simple feed-forward IT2 FNNs learning. The adoption of the BBBC or the PSO will not only simplify the design of the IT2 FNNs, but will also increase identification accuracy when compared with present methods. The proposed optimization based strategies are tested with three types of interval type-2 fuzzy membership functions(IT2FMFs) and deployed on three typical identification models. Simulation results certify the effectiveness of the proposed parameter optimization methods for the IT2 FNNs.

关键词： Big bang-big crunch (BBBC) interval type-2 fuzzy neural networks (IT2FNNs) parameter optimization particle swarm optimization (PSO)

Long-term Traffic Volume Prediction Based on K-means Gaussian interval Type-2 Fuzzy Sets

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2019年第6期6卷 1344-1351页

作者： Runmei Li Yinfeng Huang Jian Wang the School of Electronic and Information Engineer ing Beijing Jiaotong University

This paper uses Gaussian interval type-2 fuzzy se theory on historical traffic volume data processing to obtain a 24-hour prediction of traffic volume with high precision. A K-means clustering method is used in this paper to get 5 minutes traffic volume variation as input data for the Gaussian interval type-2 fuzzy sets which can reflect the distribution of historical traffic volume in one statistical period. Moreover, the cluster with the largest collection of data obtained by K-means clustering method is calculated to get the key parameters of type-2 fuzzy sets, mean and standard deviation of the Gaussian membership *** the range of data as the input of Gaussian interval type-2 fuzzy sets leads to the range of traffic volume forecasting output with the ability of describing the possible range of the traffic volume as well as the traffic volume prediction data with high accuracy. The simulation results show that the average relative error is reduced to 8% based on the combined K-means Gaussian interval type-2 fuzzy sets forecasting method. The fluctuation range in terms of an upper and a lower forecasting traffic volume completely envelopes the actual traffic volume and reproduces the fluctuation range of traffic flow.

关键词： Gaussian interval type-2 fuzzy sets K-means clustering long-term prediction traffic volume traffic volume fluctuation range

Nonlinear interval analysis of rotor response with joints under uncertainties

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第1期33卷 205-218页

作者： Yanhong MA Yongfeng WANG Cun WANG Jie HONG School of Energy and Power Engineering Beihang UniversityBeijing 100083China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100083China

The dynamic influence of joints in aero-engine rotor systems is investigated in this ***,the tangential stiffness and loss factor are obtained from an isolated lap joint setup with dynamic excitation ***,the influence of the normal contact pressure and the excitation level are examined,which revel the uncertainty in ***,the updated Thin Layer Elements(TLEs)method with fitted parameters based on the experiments is established to simulate the dynamic properties of joints on the *** response of the rotor subjected to unbalance excitation is calculated,and the results illustrate the effectiveness of the proposed ***,using the Chebyshev inclusion function and a direct iteration algorithm,a nonlinear interval analysis method is established to consider the uncertainty of parameters in *** accuracy is proved by comparison with results obtained using the Monte-Carlo *** with the updated TLEs,the nonlinear Chebyshev method is successfully applied on a finite model of a *** study shows that substantial attention should be paid to the dynamical design for the joint in rotor systems,the dynamic properties of joints under complex loading and the corresponding interval analysis method need to be intensively studied.

关键词： Aero-engine Bolted joints Nonlinear interval analysis method Rotor dynamics Uncertainties Updated Thin Layer Elements(TLE)method

A Direct Method of interval Banzhaf Values of interval Cooperative Games

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2019年第3期28卷 382-391页

作者： Kairong Liang Dengfeng Li School of Economics and Management Fuzhou UniversityFuzhou 350108China School of Management and Economics University of Electronic Science and Technology of ChinaChengdu 611731China

The goal of this paper is to develop a direct method for computing interval Banzhaf values for a class of interval cooperative *** this method,it is proven that the Banzhaf values of the associated cooperative games of interval cooperative games are monotonic and non-decreasing functions of coalitions,payoffs under weaker coalition monotonicity-like *** the interval Banzhaf values can be explicitly obtained through using only the lower and upper bounds of the coalitions'interval payoffs,*** proposed method does not employ interval subtractions and hereby can effectively avoid the irrational issues such as irreversibility and uncertainty *** prove some important and desirable properties of the interval Banzhaf values and illustrate the applicability and validity of the proposed method with a numerical example.

关键词： interval cooperative game Banzhaf value group decision cooperative game

interval colorectal carcinoma:An unsolved debate

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第45期21卷 12735-12741页

作者： Mark Benedict Antonio Galvao Neto Xuchen Zhang Department of Pathology Yale University School of Medicine Department of Pathology New York University School of Medicine Pathology and Laboratory Medicine Service VA CT Healthcare System

Colorectal carcinoma(CRC), as the third most common new cancer diagnosis, poses a significant health risk to the population. interval CRCs are those that appear after a negative screening test or examination. The development of interval CRCs has been shown to be multifactorial: location of exam-academic institution versus community hospital, experience of the endoscopist, quality of the procedure, age of the patient, flat versus polypoid neoplasia, genetics, hereditary gastrointestinal neoplasia, and most significantly missed or incompletely excised lesions. The rate of interval CRCs has decreased in the last decade, which has been ascribed to an increased understanding of interval disease and technological advances in the screening of high risk individuals. In this article, we aim to review the literature with regard to the multifactorial nature of interval CRCs and provide the most recent developments regarding this important gastrointestinal entity.

关键词： Colorectal carcinoma interval colorectal carcinoma