6,301 research outputs found
The use of neural networks for the prediction of the critical factor of safety of an artificial slope subjected to earthquake forces
AbstractThis study deals with the development of Artificial Neural Network (ANN) and Multiple Regression (MR) models for estimating the critical factor of safety (Fs) value of a typical artificial slope subjected to earthquake forces. To achieve this, while the geometry of the slope and the properties of the man-made soil are kept constant, the natural subsoil properties, namely, cohesion, internal angle of friction, the bulk unit weight of the layer beneath the ground surface and the seismic coefficient, varied during slope stability analyses. Then, the Fs values of this slope were calculated using the simplified Bishop method, and the minimum (critical) Fs value for each case was determined and used in the development of the ANN and MR models. The results obtained from the models were compared with those obtained from the calculations. Moreover, several performance indices, such as determination coefficient, variance account for, mean absolute error and root mean square error, were calculated to check the prediction capacity of the models developed. The obtained indices make it clear that the ANN model has shown a higher prediction performance than the MR model
Manufacturing of B4C particle reinforced A360 aluminium cellular composite materials by the integration of stir casting and space holder methods
Stir casting method has become prominent for fabrication of metal matrix composites in recent years. This method can be adjusted for casting around space holding particles to obtain cellular composite materials. In this study, a specific method which is a combination of stir casting and space holder techniques were used to produce open-celled A360 aluminium-B4C composite foams with regular sized and distributed pores. Weight ratios of reinforcement particles determined as 0.5, 1, 1.5 and 2%. The influences of particle reinforcement on the microstructure and the mechanical behaviour of composite foams were investigated. Microstructures were analysed with optical microscope (OM), scanning electron microscope (SEM). Compression and hardness tests were carried out to observe the effects of reinforcement on mechanical properties. Compression strength properties and hardness of composites increased with the ceramic reinforcement, however the plastic strength of the composite foams showed worsening trend after a certain reinforcement ratio (0.5 wt.%). Energy absorption properties of the composite foams showed parallel trends with compressive strength properties
With four Standard Model families, the LHC could discover the Higgs boson with a few fb^-1
The existence of a 4th SM family would produce a large enhancement of the
gluon fusion channel of Higgs boson production at hadron colliders. In this
case, the SM Higgs boson could be seen at the CERN Large Hadron Collider (LHC)
via the golden mode (H->4l) with an integral luminosity of only a few fb^-1.Comment: 7 pages, 2 figures, 2 tables, references updated in v
Java Computer Animation for Effective Learning of the Cholesky Algorithm with Transportation Engineering Applications
In this paper, the well-known Cholesky Algorithm (for solving simultaneous linear equations, or SLE) is re-visited, with the ultimate goal of developing a simple, user-friendly, attractive, and useful Java Visualization and Animation Graphical User Inter-face (GUI) software as an additional teaching tool for students to learn the Cholesky factorization in a step-by-step fashion with computer voice and animation. A demo video of the Cholesky Decomposition (or factorization) animation and result can be viewed online from the website: http://www.lions.odu.edu/~imako001/cholesky/demo/index.html. The software tool developed from this work can be used for both students and their instructors not only to master this technical subject, but also to provide a dynamic/valuable tool for obtaining the solutions for homework assignments, class examinations, self-assessment studies, and other coursework related activities. Various transportation engineering applications of SLE are cited. Engineering educators who have adopted “flipped classroom instruction” can also utilize this Java Visualization and Animation software for students to “self-learning” these algorithms at their own time (and at their preferable locations), and use valuable class-meeting time for more challenging (real-life) problems’ discussions. Statistical data for comparisons of students’ performance with and without using the developed Java computer animation are also included
EEG Classification based on Image Configuration in Social Anxiety Disorder
The problem of detecting the presence of Social Anxiety Disorder (SAD) using
Electroencephalography (EEG) for classification has seen limited study and is
addressed with a new approach that seeks to exploit the knowledge of EEG sensor
spatial configuration. Two classification models, one which ignores the
configuration (model 1) and one that exploits it with different interpolation
methods (model 2), are studied. Performance of these two models is examined for
analyzing 34 EEG data channels each consisting of five frequency bands and
further decomposed with a filter bank. The data are collected from 64 subjects
consisting of healthy controls and patients with SAD. Validity of our
hypothesis that model 2 will significantly outperform model 1 is borne out in
the results, with accuracy -- higher for model 2 for each machine
learning algorithm we investigated. Convolutional Neural Networks (CNN) were
found to provide much better performance than SVM and kNNs
Detection of fungal damaged popcorn using image property covariance features
Cataloged from PDF version of article.Covariance-matrix-based features were applied to the detection of popcorn infected by a fungus that causes a symptom called "blue-eye". This infection of popcorn kernels causes economic losses due to the kernels' poor appearance and the frequently disagreeable flavor of the popped kernels. Images of kernels were obtained to distinguish damaged from undamaged kernels using image-processing techniques. Features for distinguishing blue-eye-damaged from undamaged popcorn kernel images were extracted from covariance matrices computed using various image pixel properties. The covariance matrices were formed using different property vectors that consisted of the image coordinate values, their intensity values and the first and second derivatives of the vertical and horizontal directions of different color channels. Support Vector Machines (SVM) were used for classification purposes. An overall recognition rate of 96.5% was achieved using these covariance based features. Relatively low false positive values of 2.4% were obtained which is important to reduce economic loss due to healthy kernels being discarded as fungal damaged. The image processing method is not computationally expensive so that it could be implemented in real-time sorting systems to separate damaged popcorn or other grains that have textural differences. (C) 2012 Elsevier B.V. All rights reserve
Identification of Novel Reference Genes Based on MeSH Categories
Cataloged from PDF version of article.Transcriptome experiments are performed to assess protein abundance through mRNA expression analysis. Expression levels of genes vary depending on the experimental conditions and the cell response. Transcriptome data must be diverse and yet comparable in reference to stably expressed genes, even if they are generated from different experiments on the same biological context from various laboratories. In this study, expression patterns of 9090 microarray samples grouped into 381 NCBI-GEO datasets were investigated to identify novel candidate reference genes using randomizations and Receiver Operating Characteristic (ROC) curves. The analysis demonstrated that cell type specific reference gene sets display less variability than a united set for all tissues. Therefore, constitutively and stably expressed, origin specific novel reference gene sets were identified based on their coefficient of variation and percentage of occurrence in all GEO datasets, which were classified using Medical Subject Headings (MeSH). A large number of MeSH grouped reference gene lists are presented as novel tissue specific reference gene lists. The most commonly observed 17 genes in these sets were compared for their expression in 8 hepatocellular, 5 breast and 3 colon carcinoma cells by RT-qPCR to verify tissue specificity. Indeed, commonly used housekeeping genes GAPDH, Actin and EEF2 had tissue specific variations, whereas several ribosomal genes were among the most stably expressed genes in vitro. Our results confirm that two or more reference genes should be used in combination for differential expression analysis of large-scale data obtained from microarray or next generation sequencing studies. Therefore context dependent reference gene sets, as presented in this study, are required for normalization of expression data from diverse technological backgrounds. © 2014 Ersahin et al
Attributed relational graphs for cell nucleus segmentation in fluorescence microscopy Images
Cataloged from PDF version of article.More rapid and accurate high-throughput screening
in molecular cellular biology research has become possible with
the development of automated microscopy imaging, for which
cell nucleus segmentation commonly constitutes the core step. Although
several promising methods exist for segmenting the nuclei
of monolayer isolated and less-confluent cells, it still remains an
open problem to segment the nuclei of more-confluent cells, which
tend to grow in overlayers. To address this problem, we propose a
new model-based nucleus segmentation algorithm. This algorithm
models how a human locates a nucleus by identifying the nucleus
boundaries and piecing them together. In this algorithm, we
define four types of primitives to represent nucleus boundaries
at different orientations and construct an attributed relational
graph on the primitives to represent their spatial relations. Then,
we reduce the nucleus identification problem to finding predefined
structural patterns in the constructed graph and also use the
primitives in region growing to delineate the nucleus borders.
Working with fluorescence microscopy images, our experiments
demonstrate that the proposed algorithm identifies nuclei better
than previous nucleus segmentation algorithms
Characterization of sleep spindles using higher order statistics and spectra
Cataloged from PDF version of article.This work characterizes the dynamics of sleep spindles,
observed in electroencephalogram (EEG) recorded from humans
during sleep, using both time and frequency domain methods
which depend on higher order statistics and spectra. The time domain
method combines the use of second- and third-order correlations
to reveal information on the stationarity of periodic spindle
rhythms to detect transitions between multiple activities. The frequency
domain method, based on normalized spectrum and bispectrum,
describes frequency interactions associated with nonlinearities
occuring in the observed EEG
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