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Fundamental Kinetic Modeling of Catalytic Reforming

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2009年第3期48卷 1107-1119页

作者： Sotelo-Boyas, Rogelio Froment, Gilbert F. Texas A&M Univ Artie McFerrin Dept Chem Engn College Stn TX 77843 USA

A fundamental kinetic model for the catalytic reforming process has been developed. The complex network of elementary steps and molecular reactions occurring in catalytic reforming was generated through a computer algorithm characterizing the various species by means of vectors and Boolean relation matrices. The algorithm is based on the fundamental chemistry occurring on both acid and metal sites of a Pt-Sn/Al2O3 catalyst. The number of rate coefficients for the transformations occurring on the metal sites was reduced by relating them to the nature of the involved carbon atoms. The single event concept was applied in the development of rate expressions for the elementary steps on the acid sites. This approach allows obtaining rate coefficients that are independent of the feedstock, owing to their fundamental chemical nature. The Levenberg-Marquardt algorithm was used to estimate the rate coefficients. The estimation was based on data reported from a previous naphtha reforming study in a fixed bed reactor with Pt-Sn/Al2O3 as a catalyst. The agreement between the experimental and estimated yields is excellent. The statistical tests were also satisfied. The kinetic model was used in pseudo-homogeneous and heterogeneous reactor models simulating an industrial three-bed adiabatic catalytic reformer with centripetal radial flow.

关键词： CATALYTIC reforming CHEMICAL kinetics computer algorithms METAL catalysts MATHEMATICAL models SIMULATION methods & models

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Performance of the RSNI-Picker

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SEISMOLOGICAL RESEARCH LETTERS 2014年第6期85卷 1243-1254页

作者： Spallarossa, D. Ferretti, G. Scafidi, D. Turino, C. Pasta, M. Univ Genoa Dipartimento Sci Terra Ambiente Vita I-16132 Genoa Italy

The vast volumes of seismic data being recorded by both permanent and temporary networks operating all over the world provide exciting opportunities for studying the Earth’s interior and earthquake source characteristics. As a result, the development of efficient computer algorithms and procedures capable of automatically extracting and processing such long streams of data is one of the most challenging issues facing modern seismological research. Valoroso et al. (2013) obtained an extraordinary degree of detail in the anatomy of the normal-fault system of the l’Aquila earthquake after processing around 64,000 aftershocks (extracted, picked, and located) via an automated procedure. Spectral analysis of K-NET and KiK-net data in Japan was carried out by Oth et al. (2011) on the basis of more than 67,000 records analyzed via an automated procedure that included phase picking, earthquake location, and coda identification.

关键词： Performance volumes seismic Anatomy aluminium automatic extracting seismic data Earthquakes computer algorithms Automation

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A hybrid-type active vibration isolation system using neural networks

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JOURNAL OF SOUND AND VIBRATION 1996年第4期192卷 793-805页

作者： Ahn, KG Pahk, HJ Jung, MY Cho, DW SEOUL NATL UNIV DEPT MECH DESIGN & PROD ENGNSEOULSOUTH KOREA POHANG UNIV SCI & TECHNOL DEPT IND ENGNPOHANG 790784SOUTH KOREA

Vibration isolation of mechanical systems is achieved through either passive or active vibration control systems. Although a passive vibration isolation system offers simple and reliable means to protect mechanical systems from a vibration environment, it has inherent performance limitations, that is, its controllable frequency range is limited and the shape of its transmissibility does not change. Recently, in some applications, such as active suspensions or precise vibration systems, active vibration isolation systems have been employed to overcome the limitations of the passive systems. In this paper, a hybrid-type active vibration isolation system that uses electromagnetic and pneumatic force is developed, and a new control algorithm adopting neural networks is proposed. The characteristics of the hybrid system proposed in the paper were investigated via computer simulation and experiments. It was shown that the transmissibility of the vibration isolation system could be kept below 0.63 over the entire frequency range, including the resonance frequency. (C) 1996 Academic Press Limited

关键词： Mechanical systems Vibration isolation hybrid systems isolation system active vibration isolation active suspension frequency ranges ELECTROMAGNETIC computer algorithms

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An Efficient Hierarchy Algorithm for Community Detection in Complex Networks

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MATHEMATICAL PROBLEMS IN ENGINEERING 2014年第1期2014卷 1-12页

作者： Zhang, Lili Ye, Qing Shao, Yehong Li, Chenming Gao, Hongmin Hohai Univ Coll Comp & Informat Engn Nanjing 211100 Jiangsu Peoples R China Ohio Univ Southern Ironton OH USA

Community structure is one of the most fundamental and important topology characteristics of complex networks. The research on community structure has wide applications and is very important for analyzing the topology structure, understanding the functions, finding the hidden properties, and forecasting the time-varying of the networks. This paper analyzes some related algorithms and proposes a new algorithm-CN agglomerative algorithm based on graph theory and the local connectedness of network to find communities in network. We show this algorithmis distributed and polynomial;meanwhile the simulations show it is accurate and fine-grained. Furthermore, we modify this algorithm to get one modified CN algorithm and apply it to dynamic complex networks, and the simulations also verify that the modified CN algorithm has high accuracy too.

关键词： computer networks GRAPH theory CONNECTEDNESS (Mathematics) computer algorithms computer simulation MATHEMATICAL analysis

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Colour harmonisation for images and videos via two-level graph cut

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IET IMAGE PROCESSING 2011年第7期5卷 630-643页

作者： Tang, Z. Miao, Z. Wan, Y. Jesse, F. F. Beijing Jiaotong Univ Inst Informat Sci Beijing 100044 Peoples R China

A two-level graph cut algorithm is presented to deal with the coherence preservation problem that appears when trying to perform colour harmonisation on images and videos. Region-level graph cut is a technique used to avoid harmonising disconnected areas belonging to the same object with different harmonic hues. Pixel-level graph cut is a technique used to obtain a spatially coherent harmonisation. The authors extend this algorithm to videos by employing optical flow, region growing and foreground extraction algorithms, and present a temporally consistent video harmonisation method. The proposed approach overcomes several shortcomings of the existing methods, and the experiments demonstrate the effectiveness of it.

关键词： IMAGING systems GRAPH theory computer algorithms COLOR PIXELS IMAGE processing COHERENCE (Optics)

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Three-Dimensional Dynamic Topology Optimization with Frequency Constraints Using Composite Exponential Function and ICM Method

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-10页

作者： Ye, Hongling Chen, Ning Sui, Yunkang Tie, Jun Beijing Univ Technol Coll Mech Engn & Appl Elect Beijing 100124 Peoples R China Tianjin Univ Finance & Econ Dept Math Tianjin 300222 Peoples R China

The dynamic topology optimization of three-dimensional continuum structures subject to frequency constraints is investigated using Independent Continuous Mapping (ICM) design variable fields. The composite exponential function (CEF) is selected to be a filter function which recognizes the design variables and to implement the changing process of design variables from "discrete" to "continuous" and back to "discrete." Explicit formulations of frequency constraints are given based on filter functions, first-order Taylor series expansion. And an improved optimal model is formulated using CEF and the explicit frequency constraints. Dual sequential quadratic programming (DSQP) algorithm is used to solve the optimal model. The program is developed on the platform of MSC Patran & Nastran. Finally, numerical examples are given to demonstrate the validity and applicability of the proposed method.

关键词： MATHEMATICAL optimization EXPONENTIAL functions TAYLOR'S series QUADRATIC programming computer algorithms MATHEMATICAL models

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A STUDY ON INSERTION LOSS IMPROVEMENT FOR AN OPTICAL CONNECTOR USING THE ANALYSIS OF TRANSMITTED OPTICAL-INTENSITY

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IEEE TRANSACTIONS ON COMPONENTS HYBRIDS AND MANUFACTURING TECHNOLOGY 1993年第8期16卷 768-777页

作者： CHUN, OG AHN, SH JEONG, MY CHOY, TG Component Technology Section Electronics and Telecommunications Research Institute Daejeon South Korea

In the butt-joint couPling using cylindrical ferrules and sleeve, the insertion loss of the single-mode optical connector depends on the accuracies of components that consist of optical connector (i.e., sleeve, ferrule, fiber, etc.). It is also difficult to achieve both cost reduction and performance improvement simultaneously in optical connectors because higher accuracies give better performance but cause higher cost. For single-mode fiber connection, the dimensional accuracies of currently available ferrules and optical fibers are not sufficiently high to ensure a low insertion loss with reasonable cost. Many efforts have been made to have low insertion loss without any higher order of accuracies of components. In one of the proposed methods the technique of stepwise orientation of the ferrule is used to reduce the transverse offset between butt-joint fiber cores by achieving the minimizing loss region (MLR). This method requires several stepwise rotations to make the fiber core within the MLR, which was determined by the optimal trade-off between insertion loss and working dme. In this method the insertion loss severely depends on the size of the predetermined MLR. In this paper, a new assembling method through which a very small MLR can be achieved in a short time, is proposed.

关键词： Connector Device Component Coating fiber core insertion loss Ferrule Device Component Working time optical Optical connectors assembly method computer algorithms

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Improved KLT Algorithm for High-Precision Wavelength Tracking of Optical Fiber Bragg Grating Sensors

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JOURNAL OF SENSORS 2017年第1-18期2017卷 1-10页

作者： Tosi, Daniele Nazarbayev Univ Sch Engn 53 Kabanbay Batyr Astana 010000 Kazakhstan

Fiber Bragg Gratings (FBGs) are among the most popular optical fiber sensors. FBGs are well suited for direct detection of temperature and strain and can be functionalized for pressure, humidity, and refractive index sensing. Commercial setups for FBG interrogation are based on white-light sources and spectrometer detectors, which are capable of decoding the spectrum of an FBG array. Low-cost spectrometers record the spectrum on a coarse wavelength grid (typically 78-156 pm), whereas wavelength shifts of 1 pm or lower are required by most of the applications. Several algorithms have been presented for detection of small wavelength shift, even with coarsewavelength sampling;most notably, the Karhunen-Loeve Transform(KLT) was demonstrated. In this paper, an improved algorithmbased on KLT is proposed, which is capable of further expanding the performances. Simulations show that, reproducing a commercial spectrometer with 156 pm grid, the algorithm estimates wavelength shift with accuracy well below 1 pm. In typical signal-to-noise ratio (SNR) conditions, the root mean square error is 22-220 fm, while the accuracy is 0.22 pm, despite the coarse sampling. Results have been also validated through experimental characterization. The proposed method allows achieving exceptional accuracy in wavelength tracking, beating the picometer level resolution proposed in most commercial and research software, and, due to fast operation (> 5 kHz), is compatible also with structural health monitoring and acoustics.

关键词： Bragg gratings Optical fiber detectors Wavelengths computer algorithms Spectrometers

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Distributed near lossless compression algorithm for hyperspectral images

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computerS & ELECTRICAL ENGINEERING 2014年第3期40卷 1006-1014页

作者： Nian, Yongjian He, Mi Wan, Jianwei Natl Univ Def Technol Coll Elect Sci & Engn Changsha 410073 Hunan Peoples R China Third Mil Med Univ Sch Biomed Engn Chongqing 400038 Peoples R China

This paper presents a new near lossless compression algorithm for hyperspectral images based on distributed source coding. The algorithm is performed on blocks that have the same location and size in each band. Because the importance varies from block to block along the spectral orientation, an adaptive rate allocation algorithm that weights the energy of each block under the target rate constraints is introduced. A simple linear prediction model is employed to construct the side information of each block for Slepian-Wolf coding. The relationship between the quantized step size and the allocated rate of each block is determined under the condition of correct reconstruction with the side information at the Slepian-Wolf decoder. Slepian-Wolf coding is performed on the quantized version of each block. Experimental results show that the performance of the proposed algorithm is competitive with that of state-of-the-art compression algorithms, making it appropriate for on-board compression. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： LOSSLESS data compression DISTRIBUTED computing computer algorithms HYPERSPECTRAL imaging systems CODING theory LINEAR models (Statistics)

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Larger water clusters with edges and corners on their way to ice: Structural trends elucidated with an improved parallel evolutionary algorithm

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JOURNAL OF PHYSICAL CHEMISTRY A 2006年第17期110卷 5809-5822页

作者： Bandow, Bernhard Hartke, Bernd Univ Kiel Inst Chem Phys D-24098 Kiel Germany

For the difficult task of finding global minimum energy structures for molecular clusters of nontrivial size, we present a highly efficient parallel implementation of an evolutionary algorithm. By completely abandoning the traditional concept of generations and by replacing it with a less rigid pool concept, we have managed to eliminate serial bottlenecks completely and can operate the algorithm efficiently on an arbitrary number of parallel processes. Nevertheless, our new algorithm still realizes all of the main features of our old, successful implementation. First tests of the new algorithm are shown for the highly demanding problem of water clusters modeled by a potential with flexible, polarizable monomers (TTM2-F). For this problem, our new algorithm not only reproduces all of the global minima proposed previously in considerably less CPU time but also leads to improved proposals in several cases. These, in turn, qualitatively change our earlier predictions concerning the transitions from all-surface structures to cages with a single interior molecule, and from one to two interior molecules. Furthermore, we compare preliminary results up to n = 105 with locally optimized cuts from several ice modifications. This comparison indicates that relaxed ice structures may start to be competitive already at cluster sizes above n = 90.

关键词： MICROCLUSTERS WATER ICE computer algorithms ENERGY levels (Quantum mechanics) POTENTIAL theory (Physics) MONOMERS

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