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Dimensionality Reduction for Fast Similarity Search in Large Time Series Databases 总被引:36,自引:3,他引:33
Eamonn Keogh Kaushik Chakrabarti Michael Pazzani Sharad Mehrotra 《Knowledge and Information Systems》2001,3(3):263-286
The problem of similarity search in large time series databases has attracted much attention recently. It is a non-trivial
problem because of the inherent high dimensionality of the data. The most promising solutions involve first performing dimensionality
reduction on the data, and then indexing the reduced data with a spatial access method. Three major dimensionality reduction
techniques have been proposed: Singular Value Decomposition (SVD), the Discrete Fourier transform (DFT), and more recently
the Discrete Wavelet Transform (DWT). In this work we introduce a new dimensionality reduction technique which we call Piecewise
Aggregate Approximation (PAA). We theoretically and empirically compare it to the other techniques and demonstrate its superiority.
In addition to being competitive with or faster than the other methods, our approach has numerous other advantages. It is
simple to understand and to implement, it allows more flexible distance measures, including weighted Euclidean queries, and
the index can be built in linear time.
Received 16 May 2000 / Revised 18 December 2000 / Accepted in revised form 2 January 2001 相似文献
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Content-based image retrieval (CBIR) has become one of the most active research areas in the past few years. Many visual feature representations have been explored and many systems built. In this paper, we focus on an important component of these systems - relevance feedback - and how we incorporated it into the MARS retrieval system. Relevance feedback techniques are based on an interactive retrieval approach to effectively take into account user preferences to provide an improved search experience. We present a series of coherent strategies, from single-point to multipoint and multifeature approaches that we have seamlessly integrated into our system and present experimental results to show their retrieval performance characteristics.Keywords: Image retrieval - Query refinement - Relevance feedbackMichael Ortega-Binderberger: michaelo@us.ibm.comThis work was performed while the author was a Ph.D. student at the University of Illinois at Urbana-Champaign. Correspondence to: This material is based on work supported in part by the National Science Foundation under Award Numbers CAREER IIS-9734300, 9996140, 0083489, 0331707, and 0331690 and in part by the Army Research Laboratory under Cooperative Agreement No. DAAL01-96-2-0003. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or the Army Research Laboratory. Michael Ortega-Binderberger was supported in part by CONACYT award # 89061. 相似文献
5.
Sharad V. Belsare Jasbir S. Arora 《International journal for numerical methods in engineering》1983,19(6):841-858
In this paper a new concept for development of algorithms for optimal design of engineering systems is presented. The basic idea is to use upper and lower bounds on optimum cost to develop iterative search strategies. The main feature of the concept is that it does not rely on one-dimensional search to compute a step size at any design iteration. Implication of the feature is that the algorithms based on this concept require evaluation of constraint functions only once at any design iteration. This is highly desirable for optimal design of engineering systems because evaluation of functions for such systems is very expensive due to their implicit dependence on design variables. An algorithm based on the new concept is derived in the paper. Several new step sizes are introduced and their relation to proper reduced optimal design problems are presented. A new step size based on the constant cost requirement at some design iterations is introduced. Numerical aspects for the algorithm are also presented. Based on the new algorithm, a general-purpose computer code GRP2 is developed. The code is used to solve several problems to gain experience and insight for the algorithm. Numerical experience with examples is discussed. It is concluded that algorithms based on bounding optimum cost have substantial potential for applications in optimal design of engineering systems. 相似文献
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The solar photovoltaic (PV) module output voltage changes according to the variation of light intensity and temperature. This paper presents the implementation of an automatic digital controller of a DC-DC boost converter without batteries for a solar cell module by using a peripheral interface controller, which forms a closed loop, to control the ON-OFF period of the switching pulse. The output of DC-DC converter is maintained by automatically increasing or decreasing the pulse width. To produce the pulse width modulation (PWM), the microcontroller is programmed according to the required duty cycle for the power switch. The PWM ON period is increased with the decrease in the PV voltage and vice-versa. The input voltage to the inverter is maintained constantly and is converted into an AC signal by using the metal-oxide-semiconductor field effect transistor (MOSFET) H-bridge operated in the sinusoidal pulse width modulation mode by using a PIC (peripheral interface controller) microcontroller. The generated AC signal can be connected to the AC grid or to the AC load. The simulated results by using Proteus 8 and hardware implemented results verify the effectiveness of the proposed controller. 相似文献
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Porous Hybrid Network of Graphene and Metal Oxide Nanosheets as Useful Matrix for Improving the Electrode Performance of Layered Double Hydroxides 下载免费PDF全文
Tae‐Ha Gu Jayavant L. Gunjakar In Young Kim Sharad B. Patil Jang Mee Lee Xiaoyan Jin Nam‐Suk Lee Seong‐Ju Hwang 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(32):3921-3931
Mesoporous hybrid network of reduced graphene oxide (rG‐O) and layered MnO2 nanosheets could act as an efficient immobilization matrix for improving the electrochemical activity of layered double hydroxide (LDH). The control of MnO2/rG‐O ratio is crucial in optimizing the porous structure and electrical conductivity of the resulting hybrid structure. The immobilization of Co‐Al‐LDH on hybrid MnO2/rG‐O network is more effective in enhancing its electrode activity compared with that of on pure rG‐O network. The Co‐Al‐LDH?rG‐O?MnO2 nanohybrid deliveres a greater specific capacitance than does MnO2‐free Co‐Al‐LDH?rG‐O nanohybrid. The beneficial effect of MnO2 incorporation on the electrode performance of nanohybrid is more prominent for higher current density and faster scan rate, underscoring the significant enhancement of the electron transport of Co‐Al‐LDH?rG‐O. This is supported by electrochemical impedance spectroscopy. The present study clearly demonstrates the usefulness of the porously assembled hybrid network of graphene and metal oxide nanosheets as an effective platform for exploring efficient LDH‐based functional materials. 相似文献
9.
Sharad Prasad 《乙烯基与添加剂工艺杂志》1997,3(1):12-16
In the recent past, Quality has increasingly gained in importance in the manufacturing sector on a global scale. Quality Standards like ISO-9000 series, QS-9000 series and Malcolm Baldrige National Quality Award have brought on a movement that seems to be gaining momentum by the day. Development of a Total Quality Program for any manufacturing facility must take some key factors into consideration for the program to work. The key factors that need to be considered in a PVC Compounding or a Bottle Blow Molding setup are presented in a generic format to show the merit and applicability to other manufacturing industries. Introductions to some major concepts and tools in Quality Control including Variables. Attributes, Sampling Plans, Cause–Effect Diagrams, Quality Function Deployment, Statistical Process Control and Quality Auditing are presented to measure the efficacy of the Quality Program to achieve Total Quality. 相似文献
10.
Batteries: In Situ Formation of Conductive Metal Sulfide Domain in Metal Oxide Matrix: An Efficient Way to Improve the Electrochemical Activity of Semiconducting Metal Oxide (Adv. Funct. Mater. 31/2015) 下载免费PDF全文
In Young Kim Jiyoon Seo Seung Mi Oh Sharad B. Patil Seong‐Ju Hwang 《Advanced functional materials》2015,25(31):4921-4921