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 alg...
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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.
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 sy...
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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
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 characteris...
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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.
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...
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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.
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, ferrul...
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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.
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...
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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.
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...
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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.
A fuzzy logic controller that drives a crank turning apparatus is presented. A crank turning operation with unknown initial conditions is an example of a contact operation a mechanical manipulator often finds challeng...
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A fuzzy logic controller that drives a crank turning apparatus is presented. A crank turning operation with unknown initial conditions is an example of a contact operation a mechanical manipulator often finds challenging. The apparatus presented in this manuscript uses a fuzzy logic controller that results in a simple structure and a readily realizable algorithm. computer simulations and experimental studies demonstrate favorable results offering an effective control algorithm. (C) 1998 John Wiley & Sons, Inc.
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 abandonin...
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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.
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. Becaus...
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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.
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