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El-Bealy M.O.,Military Technical College MTC | El-Bealy M.O.,Clausthal University of Technology | El-Bealy M.O.,KTH Royal Institute of Technology | El-Bealy M.O.,Massachusetts Institute of Technology
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2016

A comprehensive model of heat transfer and solidification phenomena has been developed including microstructure evolution and fluctuation macrosegregation in continuously cast steel slabs with an objective of evaluation of various mold cooling conditions. The study contains plant trials, metallographic examinations, and formulation of mathematical modeling. The plant trials involved sample collection from three slab casters in use at two different steel plants. The metallographic study combined measurements of dendrite arm spacings and macrosegregation analysis of collected samples. A one-dimensional mathematical model has been developed to characterize the thermal, solidification phases, microstructure evolution, interdendritic strain, and therefore, the macrosegregation distributions. Two cooling approaches were proposed in this study to evaluate the Newtonian heat transfer coefficient in various mold regions. The first approach is a direct estimation approach (DEA), whereas the second one is a coupled approach of the interfacial resistor model and direct estimation approach (CIR/DEA). The model predictions and standard analytical models as well as the previous measurements were compared to verify and to calibrate the model where good agreements were obtained. The comparison between the model predictions and the measurements of dendrite arm spacings and fluctuated carbon concentration profiles were performed to determine the model accuracy level with different cooling approaches. Good agreements were obtained by different accuracy levels with different cooling approaches. The model predictions of thermal parameters and isotherms were analyzed and discussed. © 2016 The Minerals, Metals & Materials Society and ASM International

El-Bealy M.O.,Military Technical College MTC | El-Bealy M.O.,Clausthal University of Technology | El-Bealy M.O.,KTH Royal Institute of Technology | El-Bealy M.O.,Massachusetts Institute of Technology
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2014

The aim of the current article is to elucidate the significant effects of macrosegregation distribution and its level on the different stages of interdendritic crack formation during dendritic solidification in continuously cast steel slabs. Couple formations of macrosegregation and interdendritic crack phenomena during dendritic solidification of peritectic carbon steels have been investigated by metallographic study of collected slab samples and by performing a set of mathematical analyses. The metallographic study involved plant trails to measure slab surface temperature of different secondary spray cooling conditions. Also, macro-microexaminations, measurements of dendrite arm spacing, macrosegregation analysis, and interdendritic distance between the dendrites of collected samples from plant trials have been performed. The experimental results show a fluctuation of carbon segregation with respect to distance from slab surface. These results also reveal that the interdendritic cracks vary with this fluctuation in various nano, macro, and microscales based on the cooling conditions. A mathematical model of heat transfer, solidification, structure evolution, interdendritic strain, macrosegregation, and elementary interdendritic area "EIA" has been developed. This model takes also into account the calculating of interdendritic distance between the dendrites "IDD" to evaluate the interdendritic crack width. The model predictions of different thermal and solidification phenomena show a good agreement with measurements. The results pointed out also that the coupled effect of interdendritic strain and macrosegregation phenomena and their distributions can be considered as the most important tools to evaluate the surface and internal interdendritic cracks in continuously cast steel slabs. The formation mechanisms of different types of interdendritic crack with interdendritic strain patterns and fluctuation of macrosegregation levels during various cooling zones have been explained, and the possible solutions to these problems have been discussed. © 2014 The Minerals, Metals & Materials Society and ASM International.

El-Bealy M.O.,Military Technical College MTC | El-Bealy M.O.,Clausthal University of Technology | El-Bealy M.O.,KTH Royal Institute of Technology | El-Bealy M.O.,Massachusetts Institute of Technology
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2016

This investigation on the formation of exuded surface segregation layer “ESSL” is intended to provide experimental and simulated comparison to verify the model developed previously by El-Bealy. Preliminary verification and calibration of the previous 2D mathematical model are demonstrated by quantitative errors between the previous measurements and predictions of temperature and macrosegregation. Also, the results from these comparisons reveal that the errors are in the reasonable and within allowable limits. These comparisons lead to the fact that the exuded surface segregation layer mostly forms on the middle slice of broad sheet ingot face and in the early stages of mold zone. The model predictions point out also that the different interdendritic strain hypotheses associated with fluctuations of mold cooling conditions. This affects the interdendritic liquid flow between the equiaxed crystals which influences the severity of ESSL formation and its macrosegregation level. The mechanism of ESSL with heat flow and interdendritic strain generation has been analyzed and discussed. The quantitative comparisons between the pervious experimental results and numerical simulation in this investigation reveal also several solutions to prevent this defect for future work. © 2015, The Minerals, Metals & Materials Society and ASM International.

El-Bealy M.O.,Military Technical College MTC | El-Bealy M.O.,Clausthal University of Technology | El-Bealy M.O.,KTH Royal Institute of Technology | El-Bealy M.O.,Massachusetts Institute of Technology
Canadian Metallurgical Quarterly | Year: 2016

Preliminary mathematical analyses of different interdendritic cracks associated with variation of heat transfer and generation of interdendritic strain in horizontal twin-roll strip casting have been investigated. A 1-D transient finite difference model of heat flow, dendritic solidification and interdendritic thermo-metallurgical strain has been developed. The model contains two cracking criteria to predict qualitatively and quantitatively the tendency of interdendritic crack formation during dendritic solidification of pure aluminium and 6022 aluminium alloy. The model predictions are compared to available analytical methods and previous measurements. This is to verify and calibrate the model where good and reasonable agreements are obtained, respectively. The variations of heat transfer modes during different contact cooling zones and their effects on the generation of interdendritic thermo-metallurgical strain at the surface and central strip locations have been analysed. The model predictions point out that the different contact cooling zones of strip surface and surroundings control the stages of interdendritic crack formation in different mushy regions. The mechanism of interdendritic crack formation in twin-roll strip casting process with previous and present cracking criteria have been explained and discussed. These discussions show the importance of selection of mathematical treatment to predict the stages of interdendritic crack formation. © 2016 Canadian Institute of Mining, Metallurgy and Petroleum.

Aly H.A.,University of Rochester | Aly H.A.,Military Technical College MTC | Sharma G.,University of Rochester
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2013

Pan-sharpening is a common post-processing operation for captured multispectral satellite imagery, where the spatial resolution of images gathered in various spectral bands is enhanced by fusing them with a panchromatic image captured at a higher resolution. Previously proposed pan-sharpening techniques operate on a per-channel basis, sharpening each multispectral band independently based on the panchromatic image, often in an ad hoc manner. In contrast with most prior techniques, we formulate pan-sharpening as the problem of jointly estimating the high resolution multispectral images to minimize the combined squared residual error in physically motivated observation models of the low resolution multispectral and the high resolution panchromatic images. To realize pan-sharpening using our proposed formulation, we develop an iterative algorithm to solve the joint minimization resulting in an overall algorithm with modest computational complexity. We evaluate our proposed algorithm and benchmark it against previously proposed methods using established quantitative measures of SNR, SAM, ERGAS, Q, and Q4 indices. Both the quantitative results and visual evaluation demonstrate that the proposed joint formulation provides superior results compared with pre-existing methods. © 2013 IEEE.

Snousy M.B.A.,The Academy of Management | El-Deeb H.M.,University for Information Science and Technology | Badran K.,Military Technical College Mtc | Khlil I.A.A.,Military Technical College Mtc
Egyptian Informatics Journal | Year: 2011

One of the major challenges in microarray analysis, especially in cancer gene expression profiles, is to determine genes or groups of genes that are highly expressed in cancer cells but not in normal cells. Supervised machine learning techniques are used with microarray datasets to build classification models that improve the diagnostic of different diseases. In this study, we compare the classification accuracy among nine decision tree methods; which are divided into two main categories; the first is single decision tree C4.5, CART, Decision Stump, Random Tree and REPTree. The second category is ensample decision tree such Bagging (C4.5 and REPTree), AdaBoost (C4.5 and REPTree), ADTree, and Random Forests. In addition to the previous comparative analyses, we evaluate the behaviors of these methods with/without applying attribute selection (A.S.) techniques such as Chi-square attribute selection and Gain Ratio attribute selection. Usually, the ensembles learning methods: bagging, boosting, and Random Forest; enhanced classification accuracy of single decision tree due to the natures of its mechanism which generate several classifiers from one dataset and vote for their classification decision. The values of enhancement fluctuate between (4.99-6.19%). In majority of datasets and classification methods, Gain ratio attribute selection slightly enhanced the classification accuracy (∼1.05%) due to the concentration on the most promising genes having the effective information gain that discriminate the dataset. Also, Chi-square attributes evaluation for ensemble classifiers slightly decreased the classification accuracy due to the elimination of some informative genes. © 2011 Faculty of Computers and Information, Cairo University. Production and hosting by Elsevier B.V. All rights reserved.

Khamis A.,Idaho State University | Naidu D.S.,University of Minnesota | Kamel A.M.,Military Technical College MTC
International Journal of Aerospace Engineering | Year: 2014

This paper presents an efficient online technique used for finite-horizon, nonlinear, stochastic, regulator, and tracking problems. This can be accomplished by the integration of the differential SDRE filter algorithm and the finite-horizon state dependent Riccati equation (SDRE) technique. Unlike the previous methods which deal with the linearized system, this technique provides finite-horizon estimation and control of the nonlinear stochastic systems. Further, the proposed technique is effective for a wide range of operating points. Simulation results of a missile guidance system are presented to illustrate the effectiveness of the proposed technique. © 2014 Ahmed Khamis et al.

Aly H.A.,Military Technical College MTC
IEEE Transactions on Information Forensics and Security | Year: 2011

This paper deals with data hiding in compressed video. Unlike data hiding in images and raw video which operates on the images themselves in the spatial or transformed domain which are vulnerable to steganalysis, we target the motion vectors used to encode and reconstruct both the forward predictive (P)-frame and bidirectional (B)-frames in compressed video. The choice of candidate subset of these motion vectors are based on their associated macroblock prediction error, which is different from the approaches based on the motion vector attributes such as the magnitude and phase angle, etc. A greedy adaptive threshold is searched for every frame to achieve robustness while maintaining a low prediction error level. The secret message bitstream is embedded in the least significant bit of both components of the candidate motion vectors. The method is implemented and tested for hiding data in natural sequences of multiple groups of pictures and the results are evaluated. The evaluation is based on two criteria: minimum distortion to the reconstructed video and minimum overhead on the compressed video size. Based on the aforementioned criteria, the proposed method is found to perform well and is compared to a motion vector attribute-based method from the literature. © 2010 IEEE.

Youssef A.M.M.,Military Technical College MTC
World Journal of Modelling and Simulation | Year: 2013

World Smart materials such as piezoelectric actuators possess useful properties especially in the field of micropositioning. Tracking control accuracy of these systems is limited due to its inherent hysteresis nonlinearity. Designing a precise tracking controller for a piezoelectric actuator with hysteresis nonlinearity is our purpose in this paper.A Bouc-Wen model is used to describe the hysteresis behavior of the actuator. Multi-parameter-optimization techniques are used twice in this paper; first for obtaining a linear model equivalent to the overall nonlinear actuator model, and second for tuning the gains of the PID controller for suppressing the tracking errors and hence getting precision tracking. Several advantages are gained on solving parameter optimization problems using computers; neither reliance on intuition nor experience in control is required, in addition to producing a satisfactory system response with optimal use of effort and time, high convergence speed, high approximation accuracy, high efficiency, and suitability for many kinds of goal functions. Simulation results performed on the nonlinear system verify the efficiency of the proposed method.

Al-Fuhaidi B.A.,Military Technical College MTC | Hassan H.E.A.,Military Technical College MTC | Salah M.M.,Military Technical College MTC | Alagooz S.S.,Military Technical College MTC
IET Communications | Year: 2012

The multi-carrier code division multiple access (MC-CDMA) is becoming a very attractive multiple access technique for high-rate data transmission in the future wireless communication systems. MC-CDMA systems transmitting over multipath channels suffer from inter-symbol interference (ISI) and multiple access interference (MAI). Recently, MC-CDMA with equalisation has attracted much attention for its ability to obtain an excellent performance even in strong frequency-selective fading channels. In this study, the proposed architecture uses the minimum mean-square error (MMSE) with parallel interference cancellation (PIC) for downlink MC-CDMA system and compared with another system based on the rake receiver with PIC for downlink MC-CDMA system. A comparison between such architectures is presented. The effect of the tentative decision functions and the effect of the loading users on the performance of the two proposed receivers are discussed and presented in this study. Simulation results show that the combination of tentative decisions with PIC and equalisation provides an efficient solution to suppress the MAI and ISI in downlink MC-CDMA systems over frequencyselective fading channels. © The Institution of Engineering and Technology 2012.

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