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Author

Haitham Alsaif

Bio: Haitham Alsaif is an academic researcher. The author has contributed to research in topics: Materials science & Metamaterial. The author has an hindex of 4, co-authored 14 publications receiving 61 citations.

Papers
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Journal ArticleDOI
TL;DR: A novel compact 2 × 2 planar MIMO antenna system with ultra-wide band capability with promising results of Envelope Correlation Coefficient and gain diversity of the design have been achieved.
Abstract: This paper presents a novel compact 2 × 2 planar MIMO antenna system with ultra-wide band capability. Antenna system is specifically designed to target lower 5th generation operating bands ranging from 2 GHz to 12 GHz. This band also covers the IEEE 802.11 a/b/g/n/ac. The antenna array geometry has been simulated using CST MWS. The design is extremely miniaturized with total structure size of mm3. The simulated and measured results have been presented. Measured and simulated return loss values for designed antenna are less than −10 dB over the operating band and lowest values of −35 dB and −32.5 dB can been seen at 5.2 GHz and 9.2 GHz, respectively, whereas at the center frequency the return loss is −25.2 dB. The mutual coupling between both elements is less than −20 dB over the transmission bandwidth. Simulated and measured radiation patterns in E and H planes at center frequency show nearly isotropic far fields. The maximum gain is measured as 4.8 dB. Promising results of Envelope Correlation Coefficient and gain diversity of the design have been achieved. Simulated and measured results are found in good agreement. The fractional bandwidth of antenna is measured as 143.2% which satisfies its ultra-wide band response.

33 citations

Journal ArticleDOI
TL;DR: The results show that optimizing the distribution network topology using the PSO approach contributed significantly to improving the reliability, node voltage, line currents, and calculation time.
Abstract: This paper presents an optimal method for optimizing network reconfiguration problems in a power distribution system in order to enhance reliability and reduce power losses. Network reconfiguration can be viewed as an optimization problem involving a set of criteria that must be reduced when adhering to various constraints. The energy not supplied (ENS) during permanent network faults and active power losses are the objective functions that are optimized in this study during the reconfiguration phase. These objectives are expressed mathematically and will be integrated into various optimization algorithms used throughout the study. To begin, a mathematical formulation of the objectives to be optimized, as well as all the constraints that must be met, is proposed. Then, to solve this difficult combinatorial problem, we use the exhaustive approach, genetic algorithm (GA), and particle swarm optimization (PSO) on an IEEE 33-bus electrical distribution network. Finally, a performance evaluation of the proposed approaches is developed. The results show that optimizing the distribution network topology using the PSO approach contributed significantly to improving the reliability, node voltage, line currents, and calculation time.

32 citations

Journal ArticleDOI
TL;DR: This paper provides an efficient method for detecting brain tumors using magnetic resonance imaging (MRI) datasets based on CNN and data augmentation and proves that it succeeded in being a contribution to previous studies in terms of both deep architectural design and high detection success.
Abstract: Brain tumor is a severe cancer and a life-threatening disease. Thus, early detection is crucial in the process of treatment. Recent progress in the field of deep learning has contributed enormously to the health industry medical diagnosis. Convolutional neural networks (CNNs) have been intensively used as a deep learning approach to detect brain tumors using MRI images. Due to the limited dataset, deep learning algorithms and CNNs should be improved to be more efficient. Thus, one of the most known techniques used to improve model performance is Data Augmentation. This paper presents a detailed review of various CNN architectures and highlights the characteristics of particular models such as ResNet, AlexNet, and VGG. After that, we provide an efficient method for detecting brain tumors using magnetic resonance imaging (MRI) datasets based on CNN and data augmentation. Evaluation metrics values of the proposed solution prove that it succeeded in being a contribution to previous studies in terms of both deep architectural design and high detection success.

19 citations

Journal ArticleDOI
TL;DR: In this paper , the authors presented a numerical study of an ultra-wideband double square ring (DSR) metamaterial absorber (MMA) for the complete visible optical wavelength region, which is designed with a three-layer (tungsten-silicon dioxide tungsten) substrate material.
Abstract: Metamaterial absorbers are very attractive due to their significant absorption behavior at optical wavelengths, which can be implemented for energy harvesting, plasmonic sensors, imaging, optical modulators, photovoltaic detectors, etc. This paper presents a numerical study of an ultra-wide-band double square ring (DSR) metamaterial absorber (MMA) for the complete visible optical wavelength region, which is designed with a three-layer (tungsten-silicon dioxide-tungsten) substrate material. Due to the symmetricity, a polarization-insensitive absorption is obtained for both transverse electric (TE) and transverse magnetic (TM) modes by simulation. An absorption above 92.2% and an average absorption of 97% are achieved in the visible optical wavelength region. A peak absorption of 99.99% is achieved at 521.83 nm. A wide range of oblique incident angle stabilities is found for stable absorption properties. A similar absorption is found for different banding angles, which may occur due to external forces during the installation of the absorber. The absorption is calculated by the interference theory (IT) model, and the polarization conversion ratio (PCR) is also validated to verify the perfect MMA. The electric field and magnetic field of the structure analysis are performed to understand the absorption property of the MMA. The presented MMA may be used in various applications such as solar cells, light detection, the biomedical field, sensors, and imaging.

18 citations

Journal ArticleDOI
TL;DR: In this paper, a cross-polarized compact antenna system is proposed for ultra wide band communications, which is a distinctive combination of multiple input multiple output (MIMO) antenna system covering radio frequency (RF) band starting from 2 GHz to 12 GHz.
Abstract: A novel cross polarized compact antenna system is proposed for Ultra Wide Band communications. It also covers the sub-6GHz band for initial 5G launch. The overall antenna system is a distinctive combination of Multiple Input Multiple Output (MIMO) antenna system covering radio frequency (RF) band starting from 2 GHz to 12 GHz. This MIMO system consists of two F-shaped monopoles with slotted fractured ground planes. The two antennas are fabricated back to back with 90 degree difference. The overall volume of the MIMO antenna system is 14 mm × 14 mm × 0.25 mm. Due to its very compact design, it is suitable for mobile phones and other hand-held devices. The peak measured gain has been achieved as 4.8 dB, and the measured far field patterns are nearly isotropic. Envelope Correlation Coefficient (ECC) and Gain Diversity are presented for the proposed MIMO antenna system.

17 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a photonic crystal (PC) microcavity laser operating at 1.3 microns was shown to have a linewidth of 0.10 nm, corresponding to a quality factor of Q 2.3x10^4.
Abstract: Sub-threshold measurements of a photonic crystal (PC) microcavity laser operating at 1.3 microns show a linewidth of 0.10 nm, corresponding to a quality factor Q ~ 1.3x10^4. The PC microcavity mode is a donor-type mode in a graded square lattice of air holes, with a theoretical Q ~ 10^5 and mode volume Veff ~ 0.25 cubic half-wavelengths in air. Devices are fabricated in an InAsP/InGaAsP multi-quantum well membrane and are optically pumped at 830 nm. External peak pump power laser thresholds as low as 100 microWatts are also observed.

184 citations

Journal ArticleDOI
01 Apr 2022-Energy
TL;DR: In this article , a new framework for the scheduling of microgrids and distribution feeder reconfiguration is presented, taking into account the uncertainties due to the load demand, market price, and renewable power generation.

62 citations

Journal ArticleDOI
02 Sep 2021-Energies
TL;DR: This article classifies the methodologies used for EMS based on the structure, control, and technique used and the untapped areas which have scope for investigation are also mentioned.
Abstract: To sustain the complexity of growing demand, the conventional grid (CG) is incorporated with communication technology like advanced metering with sensors, demand response (DR), energy storage systems (ESS), and inclusion of electric vehicles (EV). In order to maintain local area energy balance and reliability, microgrids (MG) are proposed. Microgrids are low or medium voltage distribution systems with a resilient operation, that control the exchange of power between the main grid, locally distributed generators (DGs), and consumers using intelligent energy management techniques. This paper gives a brief introduction to microgrids, their operations, and further, a review of different energy management approaches. In a microgrid control strategy, an energy management system (EMS) is the key component to maintain the balance between energy resources (CG, DG, ESS, and EVs) and loads available while contributing the profit to utility. This article classifies the methodologies used for EMS based on the structure, control, and technique used. The untapped areas which have scope for investigation are also mentioned.

51 citations

Journal ArticleDOI
TL;DR: In this article, a compact size wideband circularly polarized (CP) 2-port multiple-input-multiple-output (MIMO) antenna is designed for the fifth generation (5G) region under the sub-6 GHz band.
Abstract: A compact size wideband circularly polarized (CP) 2-port multiple-input-multiple-output (MIMO) antenna is designed for the fifth generation (5G) region under the sub-6 GHz band The presented antenna has (≤ − 10 dB) impedance bandwidth of 900 MHz (33–42 GHz) and has 100% 3-dB axial ratio bandwidth The antenna covers the potential 5G band ranging from 33 to 38 GHz having left-handed circular polarization characteristics To validate performance attributes of the MIMO antenna designed various diversity parameters such as envelope correlation coefficient (ECC), total active reflection coefficient, and diversity gain are calculated The low envelope correlation coefficient (ECC < 010) and the isolation between the antenna elements greater than 15 dB justify the acceptance of the proposed design as a MIMO antenna The proposed design exhibits good agreement between the simulated and the measured results

37 citations

Journal ArticleDOI
TL;DR: The result indicates that the placement of the proposed antenna system on the two long arms of ground plane offer adequate space for integration of lower generation antenna without adversely affecting each other’s performance.
Abstract: A low-profile planar four-element MIMO antenna is proposed in this paper that can be integrated inside wireless handheld devices. Every unit antenna is made of simple planar L-shaped monopole placed over etched non-ground area of 10 × 5 mm2. The optimized antenna elements cover three 5G New Radio bands falling within C-band: n77 band (3.3–4.2 GHz), n78 band (3.3–3.8 GHz) and n79 band (4.4–5 GHz), with isolation better than 18.8 dB, without the requirement of any additional decoupling structure. The designed antenna is fabricated on FR4 substrate of dimension 120 × 65 × 1.6 mm3. Antenna characteristics regarding reflection coefficient, mutual coupling, radiation pattern and gain are measured and discussed. The envelop correlation coefficient is computed and is lower than 0.018 for the entire range of frequency under consideration. The simplicity and compactness of the proposed MIMO antenna provides adequate space for integration of other circuits inside handheld mobile terminal. Further the integration with lower generation antennas are investigated; the result indicates that the placement of the proposed antenna system on the two long arms of ground plane offer adequate space for integration of lower generation antenna without adversely affecting each other’s performance.

34 citations