Mohamed Hesham

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Papers by Mohamed Hesham

Compact Bandpass Filter Based on Split Ring Resonators

2019 International Conference on Innovative Trends in Computer Engineering (ITCE)

The advances in communication technology stands for the need of compact size, easy to fabricate m... more The advances in communication technology stands for the need of compact size, easy to fabricate microwave devices. Herein, we propose a robust, tunable, band-pass filter, operating in the X-band (9.1 GHz). Metamaterial based on split-ring resonators (SRRs) is suggested to implement the proposed filter. The proposed design showed an improvement of 84% and 58% in the insertion loss (0.348 dB) and reflection loss (23.8 dB) respectively with respect to previous publications. In addition, the filter provided an acceptable sharpness to be utilized in radar applications. A tunability in the resonance frequency can be easily reached by changing the SRRs gap where a frequency range between 8.62 GHz and 9.46 GHz can be tuned. A fabricated filter is demonstrated where the mismatching between simulation and experimental results is justified.

Convolutional Neural Network for Arabic Speech Recognition

The Egyptian Journal of Language Engineering, 2021

This work is focused on single word Arabic automatic speech recognition (AASR). Two techniques ar... more This work is focused on single word Arabic automatic speech recognition (AASR). Two techniques are used during the feature extraction phase; Log frequency spectral coefficients (MFSC) and Gammatone-frequency cepstral coefficients (GFCC) with their first and second-order derivatives. The convolutional neural network (CNN) is mainly used to execute feature learning and classification process. CNN achieved performance enhancement in automatic speech recognition (ASR). Local connectivity, weight sharing, and pooling are the crucial properties of CNNs that have the potential to improve ASR. We tested the CNN model using an Arabic speech corpus of isolated words. The used corpus is synthetically augmented by applying different transformations such as changing the pitch, the speed, the dynamic range, adding noise, and forward and backward shift in time. It was found that the maximum accuracy obtained when using GFCC with CNN is 99.77 %. The outcome results of this work are compared to previous reports and indicate that CNN achieved better performance in AASR.

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The behavior of neutrophil extracellular traps and NADPH oxidative activity in pediatric systemic lupus erythematosus: relation to disease activity and lupus nephritis

Clinical Rheumatology, 2019

Objectives To evaluate the neutrophil extracellular traps (NETs) assay and NADPH oxidase (Nox2) a... more Objectives To evaluate the neutrophil extracellular traps (NETs) assay and NADPH oxidase (Nox2) activity in pediatric systemic lupus erythematosus (pSLE) in relation to each other and SLE characteristics. Methods This cross-sectional study included 50 children and adolescents with pSLE who were clinically evaluated and underwent routine laboratory work up of SLE (CBC, ESR, 24 hrs urinary proteins, serum creatinine, complement-3 (C3), anti-dsDNA, and antiphospholipid antibodies). NETs assay and dihydrorhodamine (DHR) test were done for patient group and 50 age-and sex-matched control group. Results The level of NETs was found significantly elevated among the patients (median 74.6 mU/ml) as compared to the controls (median 8.9 mU/ml) (p < 0.001), while values of DHR test were comparable between patients (median 95.5%) and controls (median 96.1%) (P = 0.55). There was a significant negative correlation between levels of NETs and DHR (p < 0.001). A significant positive correlation was noted between the 24 hrs urinary protein and NETs level (p < 0.001), but a significant negative correlation with DHR (p < 0.0001). Both NETs and DHR test values did not differ significantly between classes of lupus nephritis. NETs showed a significant positive correlation with anti-dsDNA titer (p = 0.004) and SLEDAI (p < 0.001), but a negative correlation with C3 (p < 0.001). DHR test was positively correlated with C3 levels (p = 0.003), but negatively correlated with anti-dsDNA titers (p = 0.008) and SLEDAI (p < 0.001). Conclusion NETs seem to have strong association with biomarkers of pSLE activity. On the other hand, Nox2 activity of the neutrophils was noted to be linked to quiescent state of SLE. Key Points • Neutrophils have displayed different actions in pSLE through the NETs and Nox2 activity. • The inverse correlation between NETs and Nox2 activity makes the later a non-fundamental pathway for NETs formation. • NETs are associated with pSLE flare and LN activity, while neutrophil Nox2 activity is related to disease remission.

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A Study on Nitrate Ion Reduction in Water with Zero-Valent Iron Loaded Nano-Titania Prepared from Ilmenite Ore

Oriental Journal of Chemistry, 2016

This paper aims to synthesize titanium dioxide loaded with nano-zero valent iron (nZVI-TiO 2) fro... more This paper aims to synthesize titanium dioxide loaded with nano-zero valent iron (nZVI-TiO 2) from an inexpensive ilmenite ore. Ilmenite leachant, a solution rich in both titanium and iron ions,has been prepared by leaching ilmenite ore in hydrochloric acid. At 30% HCl, 70°C and 5 hours, almost all of iron and titanium in the ilmenite ore were dissolved. Nano titania was then produced by hydrolysis of the Ilmenite leachant in boiling water under open atmosphere and nano-zero valent iron (nZVI) was subsequently precipitated on its surface by reduction with sodium borohydride. The synthesized nZVI-TO 2 was characterized by TEM, UV-Vis absorption, XRD and EDXRF and tested for reduction of nitrate ion from water. The synthesized material showed good performance in reduction of nitrate ion in water compared with nZVI.About 40% of nitrate ion could be removed using nZVI-TO 2 from nearly neutral water after 3 hours.

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Investigation of Real� Implementation of DSP-Based DWT for Power System Protection

2005/2006 PES TD

In this paper, the performance of Discrete Wavelet Transform (DWT) is investigated. Impact of the... more In this paper, the performance of Discrete Wavelet Transform (DWT) is investigated. Impact of the type and order of the mother wavelet, sampling frequency, and the signal waveform on the DWT performance is evaluated in the scope of power system protection requirements. A novel DWT computation algorithm is introduced in order to eliminate the complexity encountered in real-time implementation. Efficacy of the proposed algorithm is verified via Digital Signal Processing (DSP) experimental tests. The results consolidate the possibility of efficient DWT realtime implementation even with higher sampling rates. Shortcomings of DWT application to power system protection are outlined and corrective recommendations are included.

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Acoustic model of the vocal tract with boundary layer corrections

IEEE International Conference on Acoustics Speech and Signal Processing, 1993

Any vocal tract model for speech synthesis tries to consider viscous losses in the vocal tract in... more Any vocal tract model for speech synthesis tries to consider viscous losses in the vocal tract in order to yield natural synthesized sound. In the present work a fluid flow approach is used to compute these losses. The boundary layer assumption helps to approximate the complete flow equations to a simple ordinary differential equation and the reflection-type line analog scattering equations.<>

Formant distortion after codecs for Arabic

2010 4th International Symposium on Communications, Control and Signal Processing (ISCCSP), 2010

Abstract In this work, we present results on the effect of wellknown mixed excitation linear pred... more

A Comparison Study on Wavelet Sparsification for Solving Acoustic Scattering Problems over a Wide Frequency Range

International Journal for Computational Methods in Engineering Science and Mechanics, 2009

... DOI: 10.1080/15502280802623255 Maha Hassanein a &amp;amp; M. Hesham a pages 91-101. Avail... more

Neural-Network Solution of the Nonuniqueness Problem in Acoustic Scattering Using Wavelets

International Journal for Computational Methods in Engineering Science and Mechanics, 2008

The solution of Helmholtz integral equation for acoustic scattering is confronted with a nonuniqu... more The solution of Helmholtz integral equation for acoustic scattering is confronted with a nonuniquness issue at the characteristic wave numbers. In this paper, a neural network-based solution to this problem is proposed. To start with, the moment matrix resulting from the discretized Helmholtz integral equation is sparsified using appropriate wavelet techniques. This sparse matrix is, further, analyzed to obtain unique patterns that characterize its structure. As a result, a proper training set of these patterns is constructed and utilized to train a back propagation neural network. The trained network is capable of predicting the scattered acoustic field for the wave numbers at which the problem doesn't suffer any nonuniqueness. Moreover, the network can also be used to obtain the scattered field even for such wavenumbers at which the nonuniqueness occurs. Comparing the neural network outputs with the exact solutions demonstrates the validity and efficiency of the proposed method.

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Neural network model for solving integral equation of acoustic scattering using wavelet basis

Communications in Numerical Methods in Engineering, 2006

In this work, neural networks (NNs) are trained in order to obtain a fast and efficient solution ... more In this work, neural networks (NNs) are trained in order to obtain a fast and efficient solution of the integral equation of acoustic scattering. Wavelets sparsification methods are utilized to reduce the NN size and complexity. The non-uniqueness problem which arises in solving this integral equation at characteristic frequencies can, also, be solved using such network without any additional computational load. Experimental results show excellent agreement between the NN-based solution and the analytical solution of a spherical scatterer.

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An efficient method for solving the nonuniqueness problem in acoustic scattering

Communications in Numerical Methods in Engineering, 2006

The problem of acoustic wave scattering by closed objects via second kind integral equations, is ... more The problem of acoustic wave scattering by closed objects via second kind integral equations, is considered. Based on, combined Helmholtz integral equation formulation (CHIEF) method, an e cient method for choosing and utilizing interior ÿeld relations is suggested for solving the nonuniqueness problem at the characteristic frequencies. The implementation of the algorithm fully utilizes previous computation and thus signiÿcantly reduces the CPU time compared to the usual least-squares treatment. The method is tested for acoustic wave scattering by both acoustically hard and soft spheres. Accurate results compared to the known exact solutions are obtained. Copyright ? 2006 John Wiley & Sons, Ltd.

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Close Accord on DWT Performance and Real-Time Implementation for Protection Applications

IEEE Transactions on Power Delivery, 2010

Abstract In this paper, a simpler and faster algorithm of discrete wavelet transform (DWT) for a ... more

Domain-limited solution of the wave equation in Riemannian coordinates

GEOPHYSICS, 2013

We propose to solve the two-way time domain acoustic wave equation in a generalized Riemannian co... more We propose to solve the two-way time domain acoustic wave equation in a generalized Riemannian coordinate system via finite-differences. The coordinate system is defined in such a way that one of its independent variables conforms to the primary wavefront, for example, using a ray coordinate system with the traveltime being one of the coordinates. At each finite-difference time-step, the solution domain is limited to a narrow corridor around the primary wavefront, leading to an increase in the computational performance. A new finite-difference scheme is introduced to stabilize the solution and facilitate its implementation. This new scheme is a blend of the simple explicit and the stable implicit schemes. As a proof of concept, the proposed method is compared to the classical explicit finite-difference scheme performed in Cartesian coordinates on two synthetic velocity models with varying complexities. At a reduced cost, the proposed method produces similar results to the classical ...

Distortion of voicing and vocal tract parameters after codecs

In this work, we present results on the effect of well-known mixed excitation linear prediction (... more In this work, we present results on the effect of well-known mixed excitation linear prediction (MELP) and code-excited linear prediction (CELP) codecs (coder/decoder) on voicing and vocal tract parameters of Arabic sounds. The study shows that the spectral distortion is large compared to other studies and is largest for MELP1200. Vowel formants have a shift which may exceed one critical band below or above its reference value. Finally, it was found that the coded pitch period did not suffer any significant change through the coding/decoding process.

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A method for selecting chief points in acoustic scattering

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On the use of discrete wavelet transform for solving integral equations of acoustic scattering

Acoustical Physics, 2010

In this paper, the discrete wavelet transform (DWT) is used to solve the dense system of equation... more In this paper, the discrete wavelet transform (DWT) is used to solve the dense system of equations which arises from integral equation of acoustic scattering. The DWT using appropriate wavelet family for acquiring larger sparsification of the system matrix is used to obtain a sparse approximation to the trans formed matrix that is used in place of the original matrix in an iterative solver. Alternatively DWT is also used to design sparse preconditioners for an iterative method. Also, DWT-based preconditioners are constructed to accelerate iterative Krylov subspace methods. Convergence rates and number of operations are discussed for each case.

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Communicating bad news in pediatric practice and its impact on child behavior

Medical Research Journal, 2011

The intrinsic properties and widespread presence of plastic particles in the marine environment h... more The intrinsic properties and widespread presence of plastic particles in the marine environment have profound effects on birds inhabiting the world's oceans. Industrial and user-plastics composed of polystyrene, polypropylene, polyethylene, styrofoam, and polyvinyl chloride are the most prevalent forms of plastic marine pollution. Their dispersal and accumulation, in average densities of 1000 to 4000 pieces km-2, are controlled by surface currents, wind patterns, and different geographic inputs. Seabirds in the order ProceUariiformes are most vulnerable to the effects of plastic ingeshon due to their smaller gizzard and their inability to regurgitate ingested plastics. Planktivores have a higher incidence of ingested plastics than do piscivores as the former are more likely to confuse plastic pellets with copepods, euphausiids, and cephalopods. Hence, &et may be a major factor determining the quantity of plastic ingested. Physiological effects related to the ingestion of plastics include obstruction of the gastrointestines and of subsequent passage of food into the intestines, blockage of gastric enzyme secretion, diminished feeding stimulus, lowered steroid hormone levels, delayed ovulation and reproductive failure. As plastic manufacture and use increases and subsequent disposal at sea becomes more extensive, the impact of dscarded plastic on birds inhabiting the marine environment may also be expected to increase. The beauty and geiiius of a work of ari nldy be reconceived, though its first material expression be destroyed; a vanished harmony may yet again inspire the composer; but when the last individual of a race of living beings breathes no more, another heaven and another earth mustpass before such a one can be again.

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