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hierarchical methods to improve the performance of the SiC-FET as SO₂ sensors in flue gas desulphurization systems

SENSORS AND ACTUATORS B-CHEMICAL 2015年 206卷 609-616页

作者： Darmastuti, Z. Bur, C. Lindqvist, N. Andersson, M. Schuetze, A. Spetz, A. Lloyd Linkoping Univ Dept Phys Chem & Biol Linkoping Sweden Alstom Power AB Vaxjo Sweden Univ Saarland Lab Measurement Technol D-66123 Saarbrucken Germany

Experiments were performed both in the laboratory and a desulfurization pilot unit in order to improve the SiC-FET sensor performance using two-step data evaluation. In both cases, a porous Pt-gate enhancement type SiC-FET was utilized in a temperature cycled operation (TCO). Liner Discriminant Analysis (LDA) was chosen as the method for multivariate data analysis. hierarchical methods with two-step LDA worked quite well in the laboratory tests with SO2 concentrations varied from 25 to 200 ppm. The same data evaluation was also applied to tests in the desulfurization pilot unit, with higher gas flow and a larger SO2 concentration range (up to 5000 ppm). The results from the SO2 quantification showed a significantly improved fit to corresponding reference instrument (FTIR) values. (C) 2014 Elsevier B.V. All rights reserved.

关键词： SO2 sensors SiC-FET Pt Temperature cycled operation (TCO) hierarchical methods Power plant

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Analysis of the effects of the global financial crisis on the Turkish economy, using hierarchical methods

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PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2012年第7期391卷 2342-2352页

作者： Kantar, Ersin Keskin, Mustafa Deviren, Bayram Erciyes Univ Dept Phys TR-38039 Kayseri Turkey Erciyes Univ Inst Sci TR-38039 Kayseri Turkey Nevsehir Univ Dept Phys TR-50300 Nevsehir Turkey

We have analyzed the topology of 50 important Turkish companies for the period 2006-2010 using the concept of hierarchical methods (the minimal spanning tree (MST) and hierarchical tree (HT)). We investigated the statistical reliability of links between companies in the MST by using the bootstrap technique. We also used the average linkage cluster analysis (ALCA) technique to observe the cluster structures much better. The MST and HT are known as useful tools to perceive and detect global structure, taxonomy, and hierarchy in financial data. We obtained four clusters of companies according to their proximity. We also observed that the Banks and Holdings cluster always forms in the centre of the MSTs for the periods 2006-2007,2008, and 2009-2010. The clusters match nicely with their common production activities or their strong interrelationship. The effects of the Automobile sector increased after the global financial crisis due to the temporary incentives provided by the Turkish government. We find that Turkish companies were not very affected by the global financial crisis. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Correlation networks hierarchical methods Bootstrap technique Stock market Global financial crisis

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Efficient parallel algorithms and software for compressed octrees with applications to hierarchical methods

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PARALLEL COMPUTING 2005年第3-4期31卷 311-331页

作者： Hariharan, B Aluru, S Iowa State Univ Sci & Technol Dept Elect & Comp Engn Ames IA 50011 USA Petrotel Inc Plano TX USA

We describe the design and implementation of efficient parallel algorithms, and a software library for the parallel implementation of compressed octree data structures. Octrees are widely used in supporting hierarchical methods for scientific applications such as the N-body problem, molecular dynamics and smoothed particle hydrodynamics. The primary goal of our work is to identify and abstract the commonalities present in various hierarchical methods using octrees, design efficient parallel algorithms for them, and encapsulate them in a software library. We designed provably efficient parallel algorithms and implementation strategies that perform well irrespective of the spatial distribution of data in the computational domain. The library will enable rapid development of applications, allowing application developers to use efficient parallel algorithms developed for this purpose, without the necessity of having detailed knowledge of the algorithms or of implementing them. The software is developed in C using the Message Passing Interface (MPI). We report experimental results on an IBM xSeries parallel computer. (c) 2005 Elsevier B.V. All rights reserved.

关键词： compressed octrees hierarchical methods parallel algorithms parallel software library parallel tree data structures

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Credit networks and systemic risk of Chinese local financing platforms: Too central or too big to fail? -based on different credit correlations using hierarchical methods

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PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2016年第0期461卷 158-170页

作者： He, Fang Chen, Xi Tongji Univ Sch Econ & Management Shanghai 200092 Peoples R China

The accelerating accumulation and risk concentration of Chinese local financing platforms debts have attracted wide attention throughout the world. Due to the network of financial exposures among institutions, the failure of several platforms or regions of systemic importance will probably trigger systemic risk and destabilize the financial system. However, the complex network of credit relationships in Chinese local financing platforms at the state level remains unknown. To fill this gap, we presented the first complex networks and hierarchical cluster analysis of the credit market of Chinese local financing platforms using the "bottom up" method from firm-level data. Based on balance-sheet channel, we analyzed the topology and taxonomy by applying the analysis paradigm of subdominant ultra -metric space to an empirical data in 2013. It is remarked that we chose to extract the network of co-financed financing platforms in order to evaluate the effect of risk contagion from platforms to bank system. We used the new credit similarity measure by combining the factor of connectivity and size, to extract minimal spanning trees (MSTs) and hierarchical trees (HTs). We found that: (1) the degree distributions of credit correlation backbone structure of Chinese local financing platforms are fat tailed, and the structure is unstable with respect to targeted failures;(2) the backbone is highly hierarchical, and largely explained by the geographic region;(3) the credit correlation backbone structure based on connectivity and size is significantly heterogeneous;(4) key platforms and regions of systemic importance, and contagion path of systemic risk are obtained, which are contributed to preventing systemic risk and regional risk of Chinese local financing platforms and preserving financial stability under the framework of macro prudential supervision. Our approach of credit similarity measure provides a means of recognizing "systemically important" institutions and regions for

关键词： Chinese local financing platforms Correlation networks Systemic risk Credit similarity measure hierarchical methods

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Investigating the Role of the Human Element in Maritime Accidents using Semi-Supervised hierarchical methods

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Transportation Research Procedia 2021年 52卷 252-259页

作者： Fadda Paolo Fancello Gianfranco Frigau Luca Mandas Marco Medda Andrea Mola Francesco Pelligra Vittorio Porta Mattia Serra Patrizia Dept. of Civil and Environmental Engineering and Architecture University of Cagliari via Marengo 2 Cagliari 09123 Italy Dept. of Economics and Business University of Cagliari V.le S. Ignazio 17 Cagliari 09123 Italy

Navigation safety is a priority both at European and global level. Despite the important progress made over the years, sea accidents remain a major concern and much work is still needed to enhance maritime safety. Knowing the causes and precursors of past accidents is essential to identify the elements on which to intervene to improve safety and reduce the possibility of an accident to occur again. In this study, 1.079 sea accidents from the International Maritime Organization (IMO) database are analyzed using Semi-supervised Recursively Partitioned Mixture Models in an attempt to identify and categorize causal themes from accident data. Special attention is devoted to the human element, which is widely recognized as a primary or precursory cause in most accidents.

关键词： Sea Accidents Clustering Sea Safety Human Factors hierarchical methods

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A New Approach to Dynamical Modeling of Water Pollution in Estuaries and its Control by hierarchical methods

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IFAC Proceedings Volumes 1983年第12期16卷 669-674页

作者： A.J. Mano Dept. de Eng. Electr do 1st. Centro de Analise e Processamento de Sinais Complexo 1. Av. Rovisco Pais 1096 Lisboa Codex Portugal

This paper is concerned with the dynamic optimal control of water quality in estuaries. A new one-dimension dynamic model is introduced, which combines an oscilating constant volume reference frame with a multistep finite difference explicit scheme for the mass balance equations. A wide class of conditions can be described by the model, including the effects of waste discharges, photosynthesis, dispersion and temperature. These effects can be time and space dependent, along an estuary of general shape. Using this model, a large scale dynamic control problem of instream aeration is formulated. To solve it, a three-level hierarchical optimization scheme, based on sequential decomposition, is presented, and applied to a numerical example.

关键词： Large-Scale Systems Decomposition hierarchical methods Optimal Control Estuarine Model Water Pollution

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hierarchical higher-order dissipative methods for transient analysis

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INTERNATIONAL JOURNAL FOR NUMERICAL methods IN ENGINEERING 2006年第12期67卷 1730-1767页

作者： Govoni, Laura Mancuso, Massimo Ubertini, Francesco Univ Bologna DISTART I-40136 Bologna Italy Univ Modena DIMC I-41100 Modena Italy

This work focuses on devising an efficient hierarchy of higher-order methods for linear transient analysis, equipped with an effective dissipative action on the spurious high modes of the response. The proposed strategy stems from the Norsett idea and is based on a multi-stage algorithm, designed to hierarchically improve accuracy while retaining the desired dissipative behaviour. Computational efficiency is pursued by requiring that each stage should involve just one set of implicit equations of the size of the problem to be solved (as standard time integration methods) and, in addition, all the stages should share the same coefficient matrix. This target is achieved by rationally formulating the methods based on the discontinuous collocation approach. The resultant procedure is shown to be well suited for adaptive solution strategies. In particular, it embeds two natural tools to effectively control the error propagation. One estimates the local error through the next-stage solution, which is one-order more accurate, the other through the solution discontinuity at the beginning of the current time step, which is permitted by the present formulation. The performance of the procedure and the quality of the two error estimators are experimentally verified on different classes of problems. Some typical numerical tests in transient heat conduction and elasto-dynamics are presented. Copyright (c) 2006 John Wiley & Sons, Ltd.

关键词： transient analysis hierarchical methods algorithmic dissipation Norsett approximants discontinuous collocation p-adaptivity

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HEIGHT DISTRIBUTIONAL DISTANCE TRANSFORM methods FOR HEIGHT FIELD RAY-TRACING

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ACM TRANSACTIONS ON GRAPHICS 1994年第4期13卷 376-399页

作者： PAGLIERONI, DW PETERSEN, SM Loral Western Development Labs

Height distributional distance transform (HDDT) methods are introduced as a new class of methods for height field ray tracing. HDDT methods utilize results of height field preprocessing. The preprocessing involves computing a height field transform representing an array of cone-like volumes of empty space above the height field surface that are as wide as possible. There is one cone-like volume balanced on its apex centered above each height field cell. Various height field transforms of this type are developed. Each is based on distance transforms of height field horizontal cross-sections. HDDT methods trace rays through empty cone-like volumes instead of through successive height field cells. The performance of HDDT methods is evaluated experimentally against existing height field ray tracing methods.

关键词： DISTANCE TRANSFORM HEIGHT FIELD hierarchical methods INCREMENTAL methods PARAMETRIC NONPARAMETRIC HDDT methods PARAMETER PLANE TRANSFORM RAY TRACING TERRAIN

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HMPMR strategy for real-time tracking in aerial images, using direct methods

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MACHINE VISION AND APPLICATIONS 2014年第5期25卷 1283-1308页

作者： Martinez, Carol Campoy, Pascual Mondragon, Ivan F. Luis Sanchez-Lopez, Jose Olivares-Mendez, Miguel A. Univ Politecn Madrid Ctr Automat & Robot CAR UPM CSIC Comp Vis Grp E-28006 Madrid Spain Pontificia Univ Javeriana Fac Engn Dept Ind Engn Bogota Colombia Univ Luxembourg Interdisciplinary Ctr Secur Reliabil & Trust SnT Automat Res Grp Luxembourg Luxembourg

The vast majority of approaches make use of features to track objects. In this paper, we address the tracking problem with a tracking-by-registration strategy based on direct methods. We propose a hierarchical strategy in terms of image resolution and number of parameters estimated in each resolution, that allows direct methods to be applied in demanding real-time visual-tracking applications. We have called this strategy the hierarchical Multi-Parametric and Multi-Resolution strategy (HMPMR). The Inverse Composition Image Alignment Algorithm (ICIA) is used as an image registration technique and is extended to an HMPMR-ICIA. The proposed strategy is tested with different datasets and also with image data from real flight tests using an Unmanned Aerial Vehicle, where the requirements of direct methods are easily unsatisfied (e.g. vehicle vibrations). Results show that using an HMPMR approach, it is possible to cope with the efficiency problem and with the small motion constraint of direct methods, conducting the tracking task at real-time frame rates and obtaining a performance that is comparable to, or even better than, the one obtained with the other algorithms that were analyzed.

关键词： Visual tracking Image registration hierarchical methods UAVs Parametric motion

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Mixed covolume methods for elliptic problems on triangular grids

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SIAM JOURNAL ON NUMERICAL ANALYSIS 1998年第5期35卷 1850-1861页

作者： Chou, SH Kwak, DY Vassilevski, PS Bowling Green State Univ Dept Math & Stat Bowling Green OH 43403 USA Korea Adv Inst Sci & Technol Dept Math Taejon 305701 South Korea Bulgarian Acad Sci Ctr Informat & Comp Technol BU-1113 Sofia Bulgaria

We consider a covolume or finite volume method for a system of first-order PDEs resulting from the mixed formulation of the variable coefficient-matrix Poisson equation with the Neumann boundary condition. The system may represent either the Darcy law and the mass conservation law in anisotropic porous media flow, or Fourier law and energy conservation. The velocity and pressure are approximated by the lowest order Raviart-Thomas space on triangles. We prove its first-order optimal rate of convergence for the approximate velocities in the L-2 -and H(div;Omega)-norms as well as for the approximate pressures in the L-2-norm. Numerical experiments are included.

关键词： MAC method mixed finite elements covolume methods finite volume methods Raviart-Thomas spaces error estimates preconditioning hierarchical methods

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