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Leukoaraiosis is associated with clinical symptom severity,poor neurological function prognosis and stroke recurrence in mild intracerebral hemorrhage:a prospective multi-center cohort study 被引量:5
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作者 Tian-Qi Xu Wei-Zhi Lin +6 位作者 Yu-Lan Feng Fan-Xia Shen Jie Chen Wei-Wen Wu Xiao-Dong Zhu Lin Gu Yi Fu 《Neural Regeneration Research》 SCIE CAS CSCD 2022年第4期819-823,共5页
Leukoaraiosis(LA)results from ischemic injury in small cerebral vessels,which may be attributable to decreased vascular density,reduced cerebrovascular angiogenesis,decreased cerebral blood flow,or microcirculatory dy... Leukoaraiosis(LA)results from ischemic injury in small cerebral vessels,which may be attributable to decreased vascular density,reduced cerebrovascular angiogenesis,decreased cerebral blood flow,or microcirculatory dysfunction in the brain.In this study,we enrolled 357 patients with mild intracerebral hemorrhage(ICH)from five hospitals in China and analyzed the relationships between LA and clinical symptom severity at admission,neurological function prognosis at 3 months,and 1-year stroke recurrence.Patients were divided into groups based on Fazekas scale scores:no LA(n=83),mild LA(n=64),moderate LA(n=98)and severe LA(n=112).More severe LA,larger hematoma volume,and higher blood glucose level at admission were associated with more severe neurological deficit.More severe LA,older age and larger hematoma volume were associated with worse neurological function prognosis at 3 months.In addition,moderate-to-severe LA,admission glucose and symptom-free cerebral infarction were associated with 1-year stroke recurrence.These findings suggest that LA severity may be a potential marker of individual ICH vulnerability,which can be characterized by poor tolerance to intracerebral attack or poor recovery ability after ICH.Evaluating LA severity in patients with mild ICH may help neurologists to optimize treatment protocols.This study was approved by the Ethics Committee of Ruijin Hospital Affiliated to Shanghai Jiao Tong University(approval No.12)on March 10,2011. 展开更多
关键词 clinical symptom severity functional dependence intracerebral hemorrhage LEUKOARAIOSIS modified Rankin scale National Institute Health of Stroke Scale PROGNOSIS stroke recurrence white matter hyperintensities
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Fast Computation of Sparse Data Cubes with Constraints 被引量:2
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作者 FengYu-cai ChenChang-qing FengJian-lin XiangLong-gang 《Wuhan University Journal of Natural Sciences》 EI CAS 2004年第2期167-172,共6页
For a data cube there are always constraints between dimensions or among attributes in a dimension, such as functional dependencies. We introduce the problem that when there are functional dependencies, how to use the... For a data cube there are always constraints between dimensions or among attributes in a dimension, such as functional dependencies. We introduce the problem that when there are functional dependencies, how to use them to speed up the computation of sparse data cubes. A new algorithm CFD (Computation by Functional Dependencies) is presented to satisfy this demand. CFD determines the order of dimensions by considering cardinalities of dimensions and functional dependencies between dimensions together, thus reduce the number of partitions for such dimensions. CFD also combines partitioning from bottom to up and aggregate computation from top to bottom to speed up the computation further. CFD can efficiently compute a data cube with hierarchies in a dimension from the smallest granularity to the coarsest one. Key words sparse data cube - functional dependency - dimension - partition - CFD CLC number TP 311 Foundation item: Supported by the E-Government Project of the Ministry of Science and Technology of China (2001BA110B01)Biography: Feng Yu-cai (1945-), male, Professor, research direction: database system. 展开更多
关键词 sparse data cube functional dependency DIMENSION PARTITION CFD
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Application of extension method to fault diagnosis of transformer 被引量:4
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作者 邓宏贵 曹建 +1 位作者 罗安 夏向阳 《Journal of Central South University of Technology》 EI 2007年第1期88-93,共6页
A novel extension diagnosis method was proposed for enhancing the diagnosis ability of the conventional dissolved gas analysis. Based on the extension theory a matter-element model was established for qualitatively an... A novel extension diagnosis method was proposed for enhancing the diagnosis ability of the conventional dissolved gas analysis. Based on the extension theory a matter-element model was established for qualitatively and quantitatively describing the fault diagnosis problem of power transformers. The degree of relation based on the dependent functions was employed to determine the nature and the grade of the faults in a transformer system. And the proposed method was verified with the experimental data. The results show that accuracy rate of the diagnosis method exceeds 90% and two kinds of faults can be detected at the same time. 展开更多
关键词 power transformer fault diagnosis extension theory matter-element model dependent function
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Multimodality magnetic resonance imaging in hepatic encephalopathy: An update 被引量:5
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作者 Xiao-Dong Zhang Long-Jiang Zhang +1 位作者 Sheng-Yong Wu Guang-Ming lu 《World Journal of Gastroenterology》 SCIE CAS 2014年第32期11262-11272,共11页
Hepatic encephalopathy(HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE.... Hepatic encephalopathy(HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE. Hyperammonaemia and neuroinflammation are two main underlying factors which contribute to the neurological alterations in HE. Both structural and functional impairments are found in the white mater and grey mater involved in HE. Although the investigations into HE pathophysiological mechanism are enormous, the exact pathophysiological causes underlying HE remain controversial. Multimodality magnetic resonance imaging(MRI) plays an important role in helping to understand the pathological process of HE. This paper reviews the up-to-date multimodality MRI methods and predominant findings in HE patients with a highlight ofthe increasingly important role of blood oxygen level dependent functional MRI. 展开更多
关键词 Hepatic encephalopathy Magnetic resonance imaging Magnetic resonance spectroscopy Diffusion weighted imaging Default-mode network Blood oxygenation level dependent functional magnetic resonance imaging
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A Systematic Study of the Relationship between RRDB and FRDB 被引量:2
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作者 Shumei Tang Qiusheng An 《南昌工程学院学报》 CAS 2006年第2期117-121,共5页
In this paper, based on rough set theory and relational database, the relationship between rough relational database (RRDB) and fuzzy relational database (FRDB) is analyzed systematically from functional dependency, n... In this paper, based on rough set theory and relational database, the relationship between rough relational database (RRDB) and fuzzy relational database (FRDB) is analyzed systematically from functional dependency, normal form and Armstrong axiom. The results show that both fuzzy functional dependency and rough functional dependency are the generalizations of classical functional dependency.Fuzzy normal form is the expansion of classical normal form while rough normal form is an independent system.RRDB and FRDB obey Armstrong axiom to some extent from the point of view of inference rule. 展开更多
关键词 functional dependency normal form rough set RRDB FRDB
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The Cox-Aalen Models as Framework for Construction of Bivariate Probability Distributions, Universal Representation 被引量:1
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作者 Jerzy K. Filus 《Journal of Statistical Science and Application》 2017年第2期56-63,共8页
Starting with the Aalen (1989) version of Cox (1972) 'regression model' we show the method for construction of "any" joint survival function given marginal survival functions. Basically, however, we restrict o... Starting with the Aalen (1989) version of Cox (1972) 'regression model' we show the method for construction of "any" joint survival function given marginal survival functions. Basically, however, we restrict ourselves to model positive stochastic dependences only with the general assumption that the underlying two marginal random variables are centered on the set of nonnegative real values. With only these assumptions we obtain nice general characterization of bivariate probability distributions that may play similar role as the copula methodology. Examples of reliability and biomedical applications are given. 展开更多
关键词 Cox model Aalen additive hazards model construction of bivariate probability distributions givenmarginal distributions "joiner" as dependence function "connecting" the marginals general characterization ofbivariate distributions similarity to the copula methodology reliability and biomedical applications
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DPIF:A Framework for Distinguishing Unintentional Quality Problems From Potential Shilling Attacks
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作者 Mohan Li Yanbin Sun +3 位作者 Shen Su Zhihong Tian Yuhang Wang Xianzhi Wang 《Computers, Materials & Continua》 SCIE EI 2019年第4期331-344,共14页
Maliciously manufactured user profiles are often generated in batch for shilling attacks.These profiles may bring in a lot of quality problems but not worthy to be repaired.Since repairing data always be expensive,we ... Maliciously manufactured user profiles are often generated in batch for shilling attacks.These profiles may bring in a lot of quality problems but not worthy to be repaired.Since repairing data always be expensive,we need to scrutinize the data and pick out the data that really deserves to be repaired.In this paper,we focus on how to distinguish the unintentional data quality problems from the batch generated fake users for shilling attacks.A two-steps framework named DPIF is proposed for the distinguishment.Based on the framework,the metrics of homology and suspicious degree are proposed.The homology can be used to represent both the similarities of text and the data quality problems contained by different profiles.The suspicious degree can be used to identify potential attacks.The experiments on real-life data verified that the proposed framework and the corresponding metrics are effective. 展开更多
关键词 Data quality shilling attacks functional dependency suspicious degree HOMOLOGY
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An Optimized Approach for Extracting Approximate Functional Dependencies in XML Documents
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作者 SHI Lei YANG Xiao-chun YU Ge WANG Bin ZHOU Hua-hui 《Wuhan University Journal of Natural Sciences》 EI CAS 2006年第1期127-132,共6页
In this paper, the definition of approximate XFDs based on value equality is proposed. Two metrics, sup port and strength, are presented for measuring the degree of approximate XFD. A basic algorithm is designed for e... In this paper, the definition of approximate XFDs based on value equality is proposed. Two metrics, sup port and strength, are presented for measuring the degree of approximate XFD. A basic algorithm is designed for extracting minimal set of approximate XFDs, and then two optimized strategies are proposed to improve the performance. Finally, the experimental results show that the optimized algorithms are correct and effective. 展开更多
关键词 XML functional dependencies strength of functional dependencies
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Functional Dependencies and Its Axiom System in XML
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作者 ZHAO Xiangguo WANG Guoren HOU Huan DING Dabin 《Wuhan University Journal of Natural Sciences》 CAS 2007年第5期845-849,共5页
According to the analysis of existing complicated functional dependencies constraint, we conclude the conditions of defining functional dependency in XML, and then we introduce the concept of the node value equality. ... According to the analysis of existing complicated functional dependencies constraint, we conclude the conditions of defining functional dependency in XML, and then we introduce the concept of the node value equality. A new path language and a new definition of functional dependencies in XML (XFD) are proposed XFD includes the relative XFD and the absolute XFD, in which absolute key and relative key are the particular cases. We focus on the logical implication and the closure problems, and propose a group of inference rules. Finally, some proofs of the correctness and completeness are given. XFD is powerful on expressing functional dependencies in XML causing data redundancy, and has a complete axiom system. 展开更多
关键词 XML functional dependencies path language inference rule
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Stability analysis of nonlinear Roesser-type two-dimensional systems via a homogenous polynomial technique
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作者 张铁岩 赵琰 解相朋 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第12期109-117,共9页
This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional (2D) systems. Firstly, the fuzzy modeling method for the usual one-dimensional (1D) systems is extended to t... This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional (2D) systems. Firstly, the fuzzy modeling method for the usual one-dimensional (1D) systems is extended to the 2D ease so that the underlying nonlinear 2D system can be represented by the 2D Takagi Sugeno (TS) fuzzy model, which is convenient for implementing the stability analysis. Secondly, a new kind of fuzzy Lyapunov function, which is a homogeneous polynomially parameter dependent on fuzzy membership functions, is developed to conceive less conser- vative stability conditions for the TS Roesser-type 2D system. In the process of stability analysis, the obtained stability conditions approach exactness in the sense of convergence by applying some novel relaxed techniques. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed approach. 展开更多
关键词 stability analysis Roesser model two-dimensional nonlinear systems parameter- dependent Lyapunov function
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Developmental dependence for functional eye regrowth in Xenopus laevis
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作者 Cindy X.Kha Kelly Ai-Sun Tseng 《Neural Regeneration Research》 SCIE CAS CSCD 2018年第10期1735-1737,共3页
Introduction:A key challenge in designing tissue repair strategies is knowing whether and how developmental mechanisms are used for successful repair of mature/adult tissues.Although it is known that developmental co... Introduction:A key challenge in designing tissue repair strategies is knowing whether and how developmental mechanisms are used for successful repair of mature/adult tissues.Although it is known that developmental components are used in repair,it remains mostly unclear which ones are required and whether they act similarly as during development.This issue is further complicated by the fact that it is difficult. 展开更多
关键词 Developmental dependence for functional eye regrowth in Xenopus laevis FIGURE RI
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Improve Data Quality by Processing Null Values and Semantic Dependencies
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作者 Houda Zaidi Faouzi Boufarès Yann Pollet 《Journal of Computer and Communications》 2016年第5期78-85,共8页
Today, the quantity of data continues to increase, furthermore, the data are heterogeneous, from multiple sources (structured, semi-structured and unstructured) and with different levels of quality. Therefore, it is v... Today, the quantity of data continues to increase, furthermore, the data are heterogeneous, from multiple sources (structured, semi-structured and unstructured) and with different levels of quality. Therefore, it is very likely to manipulate data without knowledge about their structures and their semantics. In fact, the meta-data may be insufficient or totally absent. Data Anomalies may be due to the poverty of their semantic descriptions, or even the absence of their description. In this paper, we propose an approach to better understand the semantics and the structure of the data. Our approach helps to correct automatically the intra-column anomalies and the inter-col- umns ones. We aim to improve the quality of data by processing the null values and the semantic dependencies between columns. 展开更多
关键词 Data Quality Big Data Contextual Semantics Semantic Dependencies Functional Dependencies Null Values Data Cleaning
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The Effects of Oxidation States and Spin States of Chromium Interaction with <i>Sargassum Sp</i>.: A Spectroscopic and Density Functional Theoretical Study
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作者 Mohammad Abdul Matin Md. Aftab Ali Shaikh +3 位作者 Md. Anwar Hossain Md. Alauddin Tapas Debnath Mohammed Abdul Aziz 《Green and Sustainable Chemistry》 2021年第4期125-141,共17页
The study of various oxidation states of chromium with Sargassum <i>sp</i>. is of particular interest since hexavalent chromium </span><span style="font-size:10.0pt;font-family:""&g... The study of various oxidation states of chromium with Sargassum <i>sp</i>. is of particular interest since hexavalent chromium </span><span style="font-size:10.0pt;font-family:"">is </span><span style="font-size:10.0pt;font-family:"">reduced to trivalent chromium in </span><span style="font-size:10.0pt;font-family:"">an </span><span style="font-size:10.0pt;font-family:"">aqueous solution. In this study, a systematic density functional theory (DFT) calculations were performed to study the interactions of transition metal chromium ion with different oxidation states and spin states with the <i>Sar</i></span><i><span style="font-size:10.0pt;font-family:"">gassum sp</span></i><span style="font-size:10.0pt;font-family:"">. decorated with carboxylate</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">(acetate) at the wB97XD/6-311++</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">G(d,p)</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">level of theory. The structures and binding energies of chromium met<span>al</span></span><span style="font-size:10.0pt;font-family:"">-</span><span style="font-size:10.0pt;font-family:"">carboxylate complexes at various oxidation states and spin states in gas</span><span style="font-size:10.0pt;font-family:""> phase were examined. The coordination strength of Cr(VI) with the acetate <span>ligand was predominantly the strongest compare</span></span><span style="font-size:10.0pt;font-family:"">d</span><span style="font-size:10.0pt;font-family:""> to the other oxidation</span><span style="font-size:10.0pt;font-family:""> states. <span>Vibrational frequency analysis, for the homoleptic monomers of tris</span> <span>[</span><span>Cr<sup>III</sup>(AC)<sub>3</sub>]<sup>0</sup> and </span>[Cr<sup>VI</sup>(AC)<sub>3</sub>]<sup>3+</sup> complexes, illustrate good harmony with the experimental and<span> theoretical calculated frequencies. Using the time</span></span><span style="font-size:10.0pt;font-family:"">-</span><span style="font-size:10.0pt;font-family:"">dependent DFT</span><span style="font-size:10.0pt;font-family:""> (TD-DFT) at the level of CAM-B3LYP/6-311++G(d,p), the vertical excitation energies were obtained. The stabilization energies derived using the second order perturbation </span><span style="font-size:10.0pt;font-family:"">theory, <i>E</i><sub>ij</sub><sup>(2)</sup>, of NBO analysis confirmed the greater charge transfer for the</span><span style="font-size:10.0pt;font-family:""> observed trends in the metal binding. The calculated binding </span><span style="font-size:10.0pt;font-family:"">energies</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">(ΔE) and interactions energies </span><span style="font-size:10.0pt;font-family:Symbol;">S</span><i><span style="font-size:10.0pt;font-family:"">E</span></i><sub><span style="font-size:10.0pt;font-family:"">ij</span></sub><sup><span style="font-size:10.0pt;font-family:"">(2)</span></sup><span style="font-size:10.0pt;font-family:""> favor</span><span style="font-size:10.0pt;font-family:""> </span><span style="font-size:10.0pt;font-family:"">the formation of</span><span style="font-size:10.0pt;font-family:""> [Cr<sup>VI</sup>(AC)<sub>3</sub>]<sup>3+</sup> complexes. The findings of this study identify efficient electronic factors as major contributors to the metal binding affinities, with promising possibilities for the design of metal-ligand complexes and sensing of the metal ions. 展开更多
关键词 Transition Metal Time Dependent Density Functional Theory Binding Energy Spectroscopy Electronic Properties and Homoleptic Coordinated Complex
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THE INTEGRAL AS A FUNCTlON OF THE UPPER LIMIT AND DEPENDING ON A PARAMETER TO SOLVE DRAWING THROUGH IDLING ROLLS
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作者 赵德文 赵志业 张强 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1994年第1期93-100,共8页
The relocity and sirain-rate .field which are different from Avilzur's have beenestablished in Caitesian coordinates. Using the integral as a function of the upper limitand integration depending on a parameler, an... The relocity and sirain-rate .field which are different from Avilzur's have beenestablished in Caitesian coordinates. Using the integral as a function of the upper limitand integration depending on a parameler, an analylical upper-bound solution todrawing stress through idling rolls has been obtained in this paper. 展开更多
关键词 drawing through idling rolls integral as a function of theupper limit. integration depending on a parameter analyticalsolution
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Rheological Behaviour for Polymer Melts and Concentrated Solutions Part Ⅲ: A New Multiple Entanglement Model to Predict the Dependence of Linear Viscoelastic Function (η_0, Ψ_(10)~0,η_(ext)~0) on the Ranges of Primary Molecular Weights and the Species of Polymers 被引量:1
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作者 Mingshi SONG and Jincai YANG (Research Institute of Polymeric Materials, Beijing University of Chemical Technology, Beijing, 100029, China)Yiding SHEN(North West Institute of Light Industry, Shanxi Xianyang, 712087, China) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1995年第3期197-208,共12页
It is shown theoretically that the viscoelasticity of polymer melts is determined by three combining factorst they are the primary molecular weight and its distribution, the number of entanglement sites on polymer cha... It is shown theoretically that the viscoelasticity of polymer melts is determined by three combining factorst they are the primary molecular weight and its distribution, the number of entanglement sites on polymer chain and the sequence distribution of constituent chains in entanglement spacings. A unified quantity for the three combing factors is the average constrained dimensional number of constituent chains in the long entanglement spacings (v). A new relation of v to the primary molecular weight and the number of testing polymers were derived from the multiple entanglement and reptation model, and a new method for determining v was proposed. The dependences of linear viscoelastic functions on the primary molecular weight and its distribution were derived by the statistical method. When Mn=6Me to 18 Me, the values of (v) can range from 3.33 to 3.70. Their values are in a good agreement with the experiment data, and it can slightjy vary with the different species of polymers and the different ranges of molecular weight of polymers 展开更多
关键词 exp EXT A New Multiple Entanglement Model to Predict the Dependence of Linear Viscoelastic Function Rheological Behaviour for Polymer Melts and Concentrated Solutions Part
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Fast Algorithms of Mining Probability Functional Dependency Rules in Relational Database 被引量:1
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作者 陶晓鹏 周傲英 胡运发 《Journal of Computer Science & Technology》 SCIE EI CSCD 2000年第3期261-270,共10页
This paper defines a new kind of rule, probability functional dependency rule. The functional dependency degree can be depicted by this kind of rule. Five algorithms, from the simple to the complex, are presefited to ... This paper defines a new kind of rule, probability functional dependency rule. The functional dependency degree can be depicted by this kind of rule. Five algorithms, from the simple to the complex, are presefited to mine this kind of rule in different condition. The related theorems are proved to ensure the high efficiency and the correctness of the above algorithms. 展开更多
关键词 data mining functional dependency relationship (FD) probability functional dependency rule (PFDR) relational database
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Discovering context-aware conditional functional dependencies 被引量:1
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作者 Yuefeng DU Derong SHEN +2 位作者 Tiezheng NIE Yue KOU Ge YU 《Frontiers of Computer Science》 SCIE EI CSCD 2017年第4期688-701,共14页
Conditional functional dependencies(CFDs) are important techniques for data consistency. However, CFDs are limited to 1) provide the reasonable values for consistency repairing and 2) detect potential errors. This... Conditional functional dependencies(CFDs) are important techniques for data consistency. However, CFDs are limited to 1) provide the reasonable values for consistency repairing and 2) detect potential errors. This paper presents context-aware conditional functional dependencies(CCFDs) which contribute to provide reasonable values and detect po- tential errors. Especially, we focus on automatically discov- ering minimal CCFDs. In this paper, we present context rela- tivity to measure the relationship of CFDs. The overlap of the related CFDs can provide reasonable values which result in more accuracy consistency repairing, and some related CFDs are combined into CCFDs. Moreover, we prove that discover- ing minimal CCFDs is NP-complete and we design the pre- cise method and the heuristic method. We also present the dominating value to facilitate the process in both the precise method and the heuristic method. Additionally, the context relativity of the CFDs affects the cleaning results. We will give an approximate threshold of context relativity accord- ing to data distribution for suggestion. The repairing results are approved more accuracy, even evidenced by our empirical evaluation. 展开更多
关键词 conditional functional dependencies contextaware rules discovery
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Min-max model predictive control for constrained nonlinear systems via multiple LPV embeddings 被引量:1
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作者 ZHAO Min LINing LI ShaoYuan 《Science in China(Series F)》 2009年第7期1129-1135,共7页
A min-max model predictive control strategy is proposed for a class of constrained nonlinear system whose trajectories can be embedded within those of a bank of linear parameter varying (LPV) models. The embedding L... A min-max model predictive control strategy is proposed for a class of constrained nonlinear system whose trajectories can be embedded within those of a bank of linear parameter varying (LPV) models. The embedding LPV models can yield much better approximation of the nonlinear system dynamics than a single LTV model. For each LPV model, a parameter-dependent Lyapunov function is introduced to obtain poly-quadratically stable control law and to guarantee the feasibility and stability of the origi- nal nonlinear system. This approach can greatly reduce computational burden in traditional nonlinear predictive control strategy. Finally a simulation example illustrating the strategy is presented. 展开更多
关键词 constrained nonlinear systems predictive control LPV embedding parameter dependent Lyapunov function LMI
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Determining the Real Data Completeness of a Relational Dataset
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作者 Yong-Nan Liu Jian-Zhong Li Zhao-Nian Zou 《Journal of Computer Science & Technology》 SCIE EI CSCD 2016年第4期720-740,共21页
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 comm... 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 it.Little 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. 展开更多
关键词 data quality data completeness functional dependency data completeness model optimal algorithm
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Reliability evaluation of PMS considering coupling effect of functional and physical dependency
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作者 Ying CHEN Qichao MA Rui KANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第2期154-163,共10页
Aviation and aerospace system are typical Phased-Mission Systems(PMSs)featured with varying configuration,phased load condition and cross phase failure correlation.The coupling effect of Functional Dependency(FDEP)and... Aviation and aerospace system are typical Phased-Mission Systems(PMSs)featured with varying configuration,phased load condition and cross phase failure correlation.The coupling effect of Functional Dependency(FDEP)and Physical Dependency(PDEP)has a unique influence on the failure behavior of PMS.In this article,the coupling effect is analyzed,and the degradation of components is modeled with the positive drift wiener process,in which the drift coefficient is related to environmental conditions and operation stress.Finally,failure behavior and system reliability are simulated.An avionics controller is studied as a case,with the degradation time distribution model and simulation algorithm,the coupling effect and dynamical system reliability can be achieved.Results show that this modeling method can describe the coupling effects of FDEP and PDEP and their influence on the failure behavior and reliability of the PMS system. 展开更多
关键词 Functional dependency Phased-mission system Physical dependency Reliability evaluation Stochastic degradation process
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