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Simulation Data (simulation + data)
Selected AbstractsCommon-refinement-based data transfer between non-matching meshes in multiphysics simulationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2004Xiangmin Jiao Abstract In multiphysics simulations using a partitioned approach, each physics component solves on its own mesh, and the interfaces between these meshes are in general non-matching. Simulation data (e.g. jump conditions) must be exchanged across the interface meshes between physics components. It is highly desirable for such data transfers to be both numerically accurate and physically conservative. This paper presents accurate, conservative, and efficient data transfer algorithms utilizing a common refinement of two non-matching surface meshes. Our methods minimize errors in a certain norm while achieving strict conservation. Some traditional methods for data transfer and related problems are also reviewed and compared with our methods. Numerical results demonstrate significant advantages of common-refinement based methods, especially for repeated transfers. While the comparisons are performed with matching geometries, this paper also addresses additional complexities associated with non-matching surface meshes and presents some experimental results from 3-D simulations using our methods. Copyright © 2004 John Wiley & Sons, Ltd. [source] Clustering multivariate time-series dataJOURNAL OF CHEMOMETRICS, Issue 8 2005Ashish Singhal Abstract A new methodology for clustering multivariate time-series data is proposed. The new methodology is based on calculating the degree of similarity between multivariate time-series datasets using two similarity factors. One similarity factor is based on principal component analysis and the angles between the principal component subspaces while the other is based on the Mahalanobis distance between the datasets. The standard K -means clustering algorithm is modified to cluster multivariate time-series datasets using similarity factors. Simulation data from two nonlinear dynamic systems: a batch fermentation and a continuous exothermic chemical reactor, are clustered to demonstrate the effectiveness of the proposed technique. Comparisons with existing clustering methods show several advantages of the proposed method. Copyright © 2006 John Wiley & Sons, Ltd. [source] Film Growth and Surface Roughness with Effective Fluctuating Covalent Bonds in Evaporating Aqueous Solution of Reactive Hydrophobic and Polar Groups: A Computer Simulation ModelMACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006Shihai Yang Abstract Summary: A computer simulation model is proposed to study film growth and surface roughness in aqueous (A) solution of hydrophobic (H) and hydrophilic (P) groups on a simple three dimensional lattice of size with an adsorbing substrate. Each group is represented by a particle with appropriate characteristics occupying a unit cube (i.e., eight sites). The Metropolis algorithm is used to move each particle stochastically. The aqueous constituents are allowed to evaporate while the concentration of H and P is constant. Reactions proceed from the substrate and bonded particles can hop within a fluctuating bond length. The film thickness () and its interface width () are examined for hardcore and interacting particles for a range of temperature (). Simulation data show a rapid increase in and followed by its non-monotonic growth and decay before reaching steady-state and near equilibrium () in asymptotic time step limit. The growth can be described by power laws, e.g., with a typical value of in initial time regime followed by at . For hardcore system, the equilibrium film thickness () and surface roughness () seem to scale linearly with the temperature, i.e., at low and at higher . For interacting functional groups in contrast, the long time (unsaturated) film thickness and surface roughness, and decay rapidly followed by a slow increase on raising the temperature. Growth of the average film thickness at a temperature . [source] An Exploratory Technique for Coherent Visualization of Time-varying Volume DataCOMPUTER GRAPHICS FORUM, Issue 3 2010A. Tikhonova Abstract The selection of an appropriate global transfer function is essential for visualizing time-varying simulation data. This is especially challenging when the global data range is not known in advance, as is often the case in remote and in-situ visualization settings. Since the data range may vary dramatically as the simulation progresses, volume rendering using local transfer functions may not be coherent for all time steps. We present an exploratory technique that enables coherent classification of time-varying volume data. Unlike previous approaches, which require pre-processing of all time steps, our approach lets the user explore the transfer function space without accessing the original 3D data. This is useful for interactive visualization, and absolutely essential for in-situ visualization, where the entire simulation data range is not known in advance. Our approach generates a compact representation of each time step at rendering time in the form of ray attenuation functions, which are used for subsequent operations on the opacity and color mappings. The presented approach offers interactive exploration of time-varying simulation data that alleviates the cost associated with reloading and caching large data sets. [source] From a Product Model to Visualization: Simulation of Indoor Flows with Lattice-Boltzmann MethodsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2004Siegfried Kühner All models are derived from a product data model based on Industry Foundation Classes. Concepts of the Lattice-Boltzmann method are described, being used as the numerical kernel of our simulation system. We take advantage of spacetrees as a central data structure for all geometry related objects. Finally, we describe some advanced postprocessing and visualization techniques allowing to efficiently analyze huge amounts of simulation data. [source] Algorithms for time synchronization of wireless structural monitoring sensorsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2005Ying Lei Abstract Dense networks of wireless structural health monitoring systems can effectively remove the disadvantages associated with current wire-based sparse sensing systems. However, recorded data sets may have relative time-delays due to interference in radio transmission or inherent internal sensor clock errors. For structural system identification and damage detection purposes, sensor data require that they are time synchronized. The need for time synchronization of sensor data is illustrated through a series of tests on asynchronous data sets. Results from the identification of structural modal parameters show that frequencies and damping ratios are not influenced by the asynchronous data; however, the error in identifying structural mode shapes can be significant. The results from these tests are summarized in Appendix A. The objective of this paper is to present algorithms for measurement data synchronization. Two algorithms are proposed for this purpose. The first algorithm is applicable when the input signal to a structure can be measured. The time-delay between an output measurement and the input is identified based on an ARX (auto-regressive model with exogenous input) model for the input,output pair recordings. The second algorithm can be used for a structure subject to ambient excitation, where the excitation cannot be measured. An ARMAV (auto-regressive moving average vector) model is constructed from two output signals and the time-delay between them is evaluated. The proposed algorithms are verified with simulation data and recorded seismic response data from multi-story buildings. The influence of noise on the time-delay estimates is also assessed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Molecular dynamics simulation of self-diffusion coefficient and its relation with temperature using simple Lennard-Jones potentialHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2008Li Wei-Zhong Abstract The diffusion coefficient is indispensable to chemical engineering design and research. In practical engineering and research, there is still a great lack of available data. Therefore, methods need to be developed to solve this problem. In this paper, a molecular dynamics simulation method is used to predict the self-diffusion coefficient for a simple fluid by using the Green, Kubo relation (VACF) and the Einstein relation (MSD). The simulation results are in good agreement with experimental findings except for an error of about 10%. The algorithm average of the two methods (AV) reduces the error to 7%. The relationship of the diffusion coefficient with temperature has also been simulated. According to the simulation data, whose correlation is all above 0.99, the diffusion coefficient agrees well with temperature following the Arrenhius relationship. Activation energy for self-diffusion has been calculated and the result were 1258(VACF), 1272(MSD), and 1265(AV) J/mol separately. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(2): 86,93, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20191 [source] Parallel DSMC method using dynamic domain decompositionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2005J.-S. Wu Abstract A general parallel direct simulation Monte Carlo method using unstructured mesh is introduced, which incorporates a multi-level graph-partitioning technique to dynamically decompose the computational domain. The current DSMC method is implemented on an unstructured mesh using particle ray-tracing technique, which takes the advantages of the cell connectivity information. In addition, various strategies applying the stop at rise (SAR) (IEEE Trans Comput 1988; 39:1073,1087) scheme is studied to determine how frequent the domain should be re-decomposed. A high-speed, bottom-driven cavity flow, including small, medium and large problems, based on the number of particles and cells, are simulated. Corresponding analysis of parallel performance is reported on IBM-SP2 parallel machine up to 64 processors. Analysis shows that degree of imbalance among processors with dynamic load balancing is about ,,½ of that without dynamic load balancing. Detailed time analysis shows that degree of imbalance levels off very rapidly at a relatively low value with increasing number of processors when applying dynamic load balancing, which makes the large problem size fairly scalable for processors more than 64. In general, optimal frequency of activating SAR scheme decreases with problem size. At the end, the method is applied to compute two two-dimensional hypersonic flows, a three-dimensional hypersonic flow and a three-dimensional near-continuum twin-jet gas flow to demonstrate its superior computational capability and compare with experimental data and previous simulation data wherever available. Copyright © 2005 John Wiley & Sons, Ltd. [source] Simulation of lid-driven cavity flows by parallel lattice Boltzmann method using multi-relaxation-time schemeINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9 2004J.-S. Wu Abstract Two-dimensional near-incompressible steady lid-driven cavity flows (Re = 100,7,500) are simulated using multi-relaxation-time (MRT) model in the parallel lattice Boltzmann BGK Bhatnager,Gross,Krook method (LBGK). Results are compared with those using single-relaxation-time (SRT) model in the LBGK method and previous simulation data using Navier,Stokes equations for the same flow conditions. Effects of variation of relaxation parameters in the MRT model, effects of number of the lattice points, improved computational convergence and reduced spatial oscillations of solution near geometrically singular points in the flow field using LBGK method due to MRT model are highlighted in the study. In summary, lattice Boltzmann method using MRT model introduces much less spatial oscillations near geometrical singular points, which is important for the successful simulation of higher Reynolds number flows. Copyright © 2004 John Wiley & Sons, Ltd. [source] Distribution learning for radio network planning tool simulationINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 12 2008Z. Nouir Abstract We propose a novel method that combines the simulation results of a model-based prediction tool with the knowledge contained in measurement data. This mixture of the a priori information and the posteriori knowledge aims at enhancing the prediction results by increasing their precision and quality. A multilayer perceptron (MLP) is trained to learn the mapping between the distributions of the measurement data and the simulation data. To make the complexity of the MLP tractable, we propose the utilization of independent component analysis (ICA). The ICA transformation makes the variables at the input of the MLP statistically independent so that it can perform its learning and generalization on individual one-dimensional distributions. Other contributions consist of the application of the k -means clustering algorithm on the incoming data and the use of the training data world model to enhance the generalization capability of the MLP. The world model consists of the aggregation of all the available data in the learning space. The proposed method is applied to a third generation mobile network to enhance the predictions of uplink and downlink base station loads. After a training performed on a given network configuration, mechanical antenna tilts are modified and we show that the results obtained by the supervised predictions are much closer to measurements than simulation results for cases that have not been encountered before. Copyright © 2008 John Wiley & Sons, Ltd. [source] A novel approach to extract accurate design parameters of PiN diodeINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 6 2007Tarek Ben Salah Abstract Accurate modelling of PiN diode transient behaviour is necessary to extract design parameters which are not documented in datasheets. To meet this requirement, this paper introduces a novel approach giving the possibility to identify accurate parameters of a given device. The used technique is based only on two stages. First, the design parameters are initialized and optimized. Second, they are refined by minimizing the cost function which depends on the transient switching parameters (IRM, VRM and trr). With a simple and CPU time-saving approach this technique leads to extract design parameters without necessarily knowing the exact technological architecture of the PiN diode. Moreover, in order to validate the proposed approach and the parameter extraction procedure three commercial diodes are tested. A good agreement between experimental and simulation data is obtained. Copyright © 2007 John Wiley & Sons, Ltd. [source] Bayesian inference in a piecewise Weibull proportional hazards model with unknown change pointsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 4 2007J. Casellas Summary The main difference between parametric and non-parametric survival analyses relies on model flexibility. Parametric models have been suggested as preferable because of their lower programming needs although they generally suffer from a reduced flexibility to fit field data. In this sense, parametric survival functions can be redefined as piecewise survival functions whose slopes change at given points. It substantially increases the flexibility of the parametric survival model. Unfortunately, we lack accurate methods to establish a required number of change points and their position within the time space. In this study, a Weibull survival model with a piecewise baseline hazard function was developed, with change points included as unknown parameters in the model. Concretely, a Weibull log-normal animal frailty model was assumed, and it was solved with a Bayesian approach. The required fully conditional posterior distributions were derived. During the sampling process, all the parameters in the model were updated using a Metropolis,Hastings step, with the exception of the genetic variance that was updated with a standard Gibbs sampler. This methodology was tested with simulated data sets, each one analysed through several models with different number of change points. The models were compared with the Deviance Information Criterion, with appealing results. Simulation results showed that the estimated marginal posterior distributions covered well and placed high density to the true parameter values used in the simulation data. Moreover, results showed that the piecewise baseline hazard function could appropriately fit survival data, as well as other smooth distributions, with a reduced number of change points. [source] Thermal Inactivation of Salmonella on Cantaloupes Using Hot WaterJOURNAL OF FOOD SCIENCE, Issue 2 2006Ethan B. Solomon ABSTRACT The inactivation of Salmonella on cantaloupes using hot water was investigated. Whole melons, inoculated with a cocktail of Salmonella isolates, were subjected to thermal treatments of various lengths in water at 65 °C, 75 °C, and 85 °C. Treatment with water at 85 °C for 60 and 90 s resulted in reductions of up to 4.7 log colony forming units (CFU) per square centimeter of rind. However, the rind of melons treated at 85 °C for 90 s were noticeably softer than the rind of melons treated for 60 s. Thermal penetration profiles were measured and computer simulations were conducted to verify the effect of hot water treatment conditions on the internal temperatures of cantaloupe melons. Experimental and simulation data indicated that the internal temperature of melons treated with hot water did not increase rapidly compared with the rind temperature. Regardless of the process temperature used, the temperature of the edible flesh, 10 mm from the surface of the rind, remained at least 40 °C cooler than the surface temperature of cantaloupe melons. These results demonstrate the utility of hot water for the inactivation of Salmonella on cantaloupes and provide a framework to producers of fresh-cut melon for the potential use of hot water as an intervention treatment. [source] Molecular and macroscopic modeling of phase separationAICHE JOURNAL, Issue 10 2000Fernando A. Escobedo Recently proposed pseudoensemble Monte Carlo methods are extended in this work to map out diverse phase diagrams (projections of the phase-coexistence hypersurface) of multicomponent mixtures required to characterize fluid-phase equilibrium phenomena and to design separation processes. Within the pseudoensemble framework, the macroscopic models of different equilibrium processes can be readily integrated to the mathematical constraints that specify the thermodynamic state of the system. The proposed Monte Carlo methods allow, for example, the simulation of isopleths and cloud-point lines to compare experimental to simulation data and to test molecular force fields. Applications of this approach include the study of retrograde phenomena in a model natural-gas mixture through simulation of dewlines and coexistence lines at constant vaporization fraction. As demonstrated, pseudoensemble simulations can also be used to generate the thermodynamic data necessary to solve problems encountered in continuous and discontinuous distillation processes. [source] Liquid-liquid equilibria of binary polymer blends: molecular thermodynamic approachMACROMOLECULAR SYMPOSIA, Issue 1 2003Bong Ho Chang Abstract We extended and simplified the modified double-lattice model to binary polymer blend systems. The model has two model parameters, C, and C,. Those are not adjustable parameters but universal functions. In comparison with Ryu et al.'s simulation data for symmetric polymer blend with various chain lengths (r1 = r2 = 8, 20, 50, 100), C, is determined. Our results show that C, is negligible for symmetric polymer blend systems. The proposed model describes very well phase behaviors of weakly interacting polymer blend systems. [source] Miniaturized elliptic bandpass filter using the novel coplanar double stepped impedance resonatorsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2006Suk-Hyung Jang Abstract This paper presents the design and experimental results of the new miniaturized elliptic coplanar bandpass filter (EC BPF) using two types of double stepped impedance resonators (DSIRs) operating at a center frequency of 1.38 GHz. Miniaturization in the proposed BPF is achieved by connecting the transmission line between the middle of two SIRs contained in a single DSIR and both grounded planes. In addition, bond-wire bridges connected between both grounded planes (which are needed in various coplanar waveguide structures) are not required. The new four-pole EC-DSIR BPF shows good agreement with the simulation data obtained by full-wave EM simulations using Zeland IE3D ver. 10.06. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1059,1063, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21600 [source] Cosmological implications of the PSCz PDF and its momentsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001Manolis Plionis We compare the probability density function (PDF) and its low-order moments (variance and skewness) of the smoothed IRAS Point Source Catalogue Redshift Survey (PSCz) galaxy density field and of the corresponding simulated PSCz look-alikes, generated from N -body simulations of six different dark matter models: four structure-normalized with and , one COBE -normalized, and the old standard cold dark matter model. The galaxy distributions are smoothed with a Gaussian window at three different smoothing scales, , 10 and 15 h,1 Mpc. We find that the simulation PSCz look-alike PDFs are sensitive only to the normalization of the power spectrum, probably owing to the shape similarity of the simulated galaxy power spectrum on the relevant scales. We find that the only models that are consistent, at a high significance level, with the observed PSCz PDF are models with a relatively low power spectrum normalization . From the phenomenologically derived ,8,moments relation, fitted from the simulation data, we find that the PSCz moments suggest . [source] Study of base series resistance losses in single and double emitter silicon solar cells through simulations and experimentsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2008K. Kotsovos Abstract This work focuses on base series resistance influence on the performance of single and double emitter rear point contact silicon solar cells. This study is performed through measurements on experimental devices with different rear contact sizes and spacings, which were designed and fabricated using standard silicon integrated circuit technology, while the results were compared with simulation data based on a 3D model developed at our institute. Simulation and experimental results show that the series resistance of the double junction structure is significantly lower compared to the single junction equivalent. In addition, it was demonstrated that the operation of both junctions under slightly different voltages improves device efficiency. Copyright © 2008 John Wiley & Sons, Ltd. [source] Profiling MS proteomics data using smoothed non-linear energy operator and Bayesian additive regression treesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 17 2009Shan He Abstract This paper proposes a novel profiling method for SELDI-TOF and MALDI-TOF MS data that integrates a novel peak detection method based on modified smoothed non-linear energy operator, correlation-based peak selection and Bayesian additive regression trees. The peak detection and classification performance of the proposed approach is validated on two publicly available MS data sets, namely MALDI-TOF simulation data and high-resolution SELDI-TOF ovarian cancer data. The results compared favorably with three state-of-the-art peak detection algorithms and four machine-learning algorithms. For the high-resolution ovarian cancer data set, seven biomarkers (m/z windows) were found by our method, which achieved 97.30 and 99.10% accuracy at 25th and 75th percentiles, respectively, from 50 independent cross-validation samples, which is significantly better than other profiling and dimensional reduction methods. The results show that the method is capable of finding parsimonious sets of biologically meaningful biomarkers with better accuracy than existing methods. Supporting Information material and MATLAB/R scripts to implement the methods described in the article are available at: http://www.cs.bham.ac.uk/szh/SourceCode-for-Proteomics.zip [source] Structure and hydration of the amylopectin trisaccharide building blocks,Synthesis, NMR, and molecular dynamicsBIOPOLYMERS, Issue 12 2008Peter I. Hansen Abstract To gain insight into the molecular details and hydration of amylopectin, the five constituting trisaccharides have been chemically synthesized as their methyl ,-glycosides. All five trisaccharides were subjected to 950 MHz NMR spectroscopy for complete assignment and nanosecond molecular dynamics trajectories were calculated to study the structure and dynamics of the trisaccharides in aqueous solution. Systematic analysis of the simulation data revealed several examples of bridging water molecules playing an important role in the stabilization of specific amylopectin conformations, which was also supported by the experimental NMR data such as interresidue NOE's and heteronuclear scalar couplings between nuclei from neighboring residues. Although ,-maltotriose, ,-iso-maltotriose, ,-panose and ,-isopanose are relatively well characterized structures, the study also includes one less characterized trisaccharide with the structure ,Glcp(1,4),Glcp(1,6),Glcp. This trisaccharide, tentatively labelled ,-forkose, is located at the branch point of amylopectin, forking the amylopectin into two strands that align into double-helical segments. The results show that the conformation of ,-forkose takes a natural bend form which fits well into the structure of the double-helical segment of amylopectin. As the only trisaccharide in this study the structure of ,-forkose is not significantly influenced by the hydration. In contrast, ,-isopanose takes a restricted, but rather extended form due to an exceptionally strong localized water density. The two homo-linkage oligomers, ,-maltotriose and ,-iso-maltotriose, showed to be the most extended and the most flexible trimers, respectively, providing regular structure for crystalline domains and maximum linker flexibility for amorphous domains. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1179,1193, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | ||||||||||||||||||||||||||||