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Interval Estimation for Aggregate Queries on Incomplete Data

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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

EntityManager： Managing Dirty Data Based on Entity Resolution

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Journal of Computer Science & Technology 2017年第3期32卷 644-662页

作者： Xue-li liu Hong-Zhi Wang jian-zhong li Hong Gao Massive Data Computing Laboratory Harbin Institute of Technology Harbin 150001 China

Data quality is important in many data-driven applications, such as decision making, data analysis, and data mining. Recent studies focus on data cleaning techniques by deleting or repairing the dirty data, which may cause information loss and bring new inconsistencies. To avoid these problems, we propose EntityManager, a general system to manage dirty data without data cleaning. This system takes real-world entity as the basic storage unit and retrieves query results according to the quality requirement of users. The system is able to handle all kinds of inconsistencies recognized by entity resolution. We elaborate the EntityManager system, covering its architecture, data model, and query processing techniques. To process queries efficiently, our system adopts novel indices, similarity operator and query optimization techniques. Finally, we verify the efficiency and effectiveness of this system and present future research challenges.

关键词： dirty data entity resolution uncertain attribute query processing query optimization

ON INSTABIliTY OF DILUTE FIBER SUSPENSIONS IN AN AXISYMMETRIC TAYLOR-COUETTE FLOW

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Journal of Hydrodynamics 2005年第4期17卷 398-403页

作者： WAN Zhan-hong liN jian-zhong li Bing-ru Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A stability analysis of flow between two coaxial rotating cylinders in the presence of fibers was performed. Based on the axisymmetric normal mode for the disturbances, a modified stability equation was derived. Then the numerical solution of the eigenvalue problem about the equation was obrained using the fourth order finite difference scheme. The marginal curves that determine the instability property were drawn. The results show that the flow instability of the dilute fiber suspensions is governed by the aspect ratio of fiber H, the inerement of H causes an increase of critical inner Reynohts number. The fiber additives effectively attenuate the instability of the flow. which is in agreement with those of related experiments.

关键词： linear stability fiber suspensions Taylor-Couette flow numerical simulation

Synthesis of Novel Scolopendra-type Polydodecyloxybenzoyl[1,5]-diazocine as New Material for Optical Sensor

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Chinese Journal of Polymer Science 2018年第6期36卷 736-741页

作者： Ya-Nan liu jian-zhong li Xiao-Bo Wan College of Chemistry and Pharmaceutical Sciences Qingdao Agricultural UniversityQingdao 266109China Qingdao institute of Bioprocess Technology Chinese Academy of ScienceQingdao 266101China

A new scolopendra-type polymer of polydodecyloxybenzoyl[1,5]-diazocine（PDBD） was designed and prepared using 2,5-bis（4-（dodecyloxy）-benzoyl）terephthaloyl azide with trifluoroacetic acid（TFA） via one-pot reaction in good yields. The structure of polymer was characterized using ~1 H-NMR, ^（13） C-NMR and MALDI-TOF spectra. The polymer PDBD exhibits good thermal stability as measured by TGA and DSC, and can be dissolved well in common organic solvents such as chloroform and tetrahydrofuran. In addition, UV-Vis spectral studies indicate that the polymer PDBD shows unique optical property changes（protonation/deprotonation） in the different trifluoroacetic acid environments. The new polymer is expected to be utilized as an optical functional material for fabricating optical sensors in environmental and biological fields.

关键词： Diazocine Scolopendra-type polymer Trifluoroacetic acid UV-Vis

Determining the Real Data Completeness of a Relational Dataset

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Journal of Computer Science & Technology 2016年第4期31卷 720-740页

作者： Yong-Nan liu jian-zhong li Zhao-Nian Zou School of Computer Science and Engineering Harbin Institute of Technology Harbin 150001 China

Low quality of data is a serious problem in the new era of big data, which can severely reduce the usability of data, mislead or bias the querying, analyzing and mining, and leads to huge loss. Incomplete data is common in low quality data, and it is necessary to determine the data completeness of a dataset to provide hints for follow-up operations on *** existing work focuses on the completeness of a dataset, and such work views all missing values as unknown values. In this paper, we study how to determine real data completeness of a relational dataset. By taking advantage of given functional dependencies, we aim to determine some missing attribute values by other tuples and capture the really missing attribute cells. We propose a data completeness model, formalize the problem of determining the real data completeness of a relational dataset, and give a lower bound of the time complexity of this problem. Two optimal algorithms to determine the data completeness of a dataset for different cases are proposed. We empirically show the effectiveness and the scalability of our algorithms on both real-world data and synthetic data.

关键词： data quality data completeness functional dependency data completeness model optimal algorithm

Efficient Partitioning Method for Optimizing the Compression on Array Data

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Journal of Computer Science & Technology 2022年第5期37卷 1049-1067页

作者： Shuai Han Xian-Min liu jian-zhong li Faculty of Computing Harbin Institute of TechnologyHarbin 150001China

Array partitioning is an important research problem in array management area,since the partitioning strategies have important influence on storage,query evaluation,and other components in array management ***,compression is highly needed for the array data due to its growing *** that the array partitioning can affect the compression performance significantly,this paper aims to design the efficient partitioning method for array data to optimize the compression *** far as we know,there still lacks research efforts on this *** this paper,the problem of array partitioning for optimizing the compression performance(PPCP for short)is firstly *** adopt a popular compression technique which allows to process queries on the compressed data without ***,because the above problem is NP-hard,two essential principles for exploring the partitioning solution are introduced,which can explain the core idea of the partitioning algorithms proposed by *** first principle shows that the compression performance can be improved if an array can be partitioned into two parts with different *** second principle introduces a greedy strategy which can well support the selection of the partitioning positions *** by the two principles,two greedy strategy based array partitioning algorithms are designed for the independent case and the dependent case *** the expensive cost of the algorithm for the dependent case,a further optimization based on random sampling and dimension grouping is proposed to achieve linear time ***,the experiments are conducted on both synthetic and real-life data,and the results show that the two proposed partitioning algorithms achieve better performance on both compression and query evaluation.

关键词： array partitioning compression performance greedy strategy NP-hard

Minimum Epsilon-Kernel Computation for Large-Scale Data Processing

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Journal of Computer Science & Technology 2022年第6期37卷 1398-1411页

作者： Hong-Jie Guo jian-zhong li Hong Gao School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China Faculty of Computer Science and Control Engineering Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518000China

Kernel is a kind of data summary which is elaborately extracted from a large *** a problem,the solution obtained from the kernel is an approximate version of the solution obtained from the whole dataset with a provable approximate *** is widely used in geometric optimization,clustering,and approximate query processing,etc.,for scaling them up to massive *** this paper,we focus on the minimumε-kernel(MK)computation that asks for a kernel of the smallest size for large-scale data *** the open problem presented by Wang et *** whether the minimumε-coreset(MC)problem and the MK problem can be reduced to each other,we first formalize the MK problem and analyze its *** to the NP-hardness of the MK problem in three or higher dimensions,an approximate algorithm,namely Set Cover-Based Minimumε-Kernel algorithm(SCMK),is developed to solve *** prove that the MC problem and the MK problem can be Turing-reduced to each ***,we discuss the update of MK under insertion and deletion operations,***,a randomized algorithm,called the Randomized Algorithm of Set Cover-Based Minimumε-Kernel algorithm(RA-SCMK),is utilized to further reduce the complexity of *** efficiency and effectiveness of SCMK and RA-SCMK are verified by experimental results on real-world and synthetic *** show that the kernel sizes of SCMK are 2x and 17.6x smaller than those of an ANN-based method on real-world and synthetic datasets,*** speedup ratio of SCMK over the ANN-based method is 5.67 on synthetic ***-SCMK runs up to three times faster than SCMK on synthetic datasets.

关键词： approximate query processing kernel large-scale dataset NP-hard

Shape Setup System for 1700 Hot Strip Mill

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Journal of Iron and Steel Research International 2007年第5期14卷 27-30页

作者： GUO zhong-feng XU jian-zhong li Chang-sheng liU Xiang-hua State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

Shape setup （SSU） system is the core technology for hot strip mill （HSM）. A precise SSU system was used to improve the strip quality for HSM. The function of SSU, setup, and feedback was introduced. The main mathematical models of roll gap profile and longitudinal strain difference are set up. Strip profile allocation strategy was researched according to the SSU system of a domestic 1 700 mm HSM. The SSU system was put into practical use and the measurement results showed that strip flatness variation and strip profile variation could be controlled in target scope.

关键词： SSU hot strip mill, shape strip profile flatness

A new C_(27)-steroidal glycoside from Ophiopogon japonicus

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Chinese Chemical Letters 2008年第1期19卷 82-84页

作者： jian zhong Wang li Ming Ye Xiao Bing Chen West China College of Pharmacy Sichuan University Chengdu 610041 China

A new C27-steroidal glycoside with three known compounds were isolated from the tuber of Ophiopogonjaponicus （Thunb.） Ker-Gawl. Based on the spectral analysis, including HRMS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HMQC and HMBC, their chemical structures were determined as pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-xylopyranosyl-（1→ 4）-13-D-gluco- pyranoside （1）, pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-glucopyranoside （2）, ophiopojaponin C （3） and ophiopogonin D （4）. 2007 jian zhong Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Ophiopogon japonicus C27-steroidal glycoside