Publications 2022

The multiple-input-multiple-output (MIMO) system consisting of multiple antenna elements faces issue of isolation performance between antenna elements. In this paper, isolation is improved by inserting a thin parasitic slit between antennas on the upper side and a plus-shaped stub in the ground plane. The proposed MIMO antenna consists of two bevelled circular antennas with a common partial ground. It is designed on FR-4 substrate having 12.5 mm x 24 mm x 1.6 mm dimensions. Bevelling is applied at the bottom of a circular patch to attain wideband performance. This antenna achieved bandwidth from 5.22 GHz to 14.89 GHz and offers isolation better than 15 dB in most of the operational bands while isolation more than 20 dB in the entire X-band. The Envelope Correlation Coefficient (ECC) of the antenna is less than 0.017 and DG is more than 9.9175. It offers an acceptable gain between 1.12 to 3 dBi and radiation efficiency between 57 to 75 %. The simulation and measurement results show good agreement. The designed MIMO antenna is compatible with WLAN (5.2 GHz to 5.8 GHz), upper C-band (5.22 GHz to 8 GHz), X-band (8 GHz to12 GHz) and lower Ku-band (12 GHz to 14.89 GHz) applications.

Publication

A Comparative Study of Hybrid Energy Storage System using Battery and Supercapacitor for Stand-Alone Solar PV System

( 2022-01-01)

Uloom N.A.

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Tunku Muhammad Nizar Tunku Mansur

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Rosnazri Ali

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Nor Hanisah Baharudin

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Abdullah A.M.

The standalone solar power system has long been used to meet the electrical needs of basic building structures. To counter the natural supply-demand imbalance caused by solar energy, standalone solar PV system often include energy storage devices, primarily lead-acid batteries. Due to lead-acid battery limitations, solar systems often have higher operational costs compared to traditional power systems. It has been discovered that a supercapacitor-battery hybrid energy storage device can be used to prolong the cycle life of a battery system by reducing the charge-discharge stress caused by variable power exchange. This research examines the influence of a supercapacitor on a photovoltaic system that makes use of a hybrid energy storage system that includes both batteries and supercapacitors in order to lessen the stress placed on the batteries. The methodology involves data collection for load profile and meteorological information, designing solar PV system, and simulation using Matlab SIMULINK to study the effect of supercapacitor on battery current of the evaluated system. Three different energy storage system topologies in building applications were simulated, and their ability in managing battery stress was investigated and evaluated. From the result, it is clear that by applying passive HES system, 53% of battery current can be reduced compared to battery-only system and 92% of reduction can be achieved by using semi-active HES system.

Publication

A Comparative Study on Generation and Composition of Food Waste in Desa Pandan Kuala Lumpur During Covid-19 Outbreak

( 2022-01-01)

Irnis Azura Zakaria

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Rashidy N.A.

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Tengku Nuraiti Tengku Izhar

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Ngaa M.H.

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Laslo L.

Food waste is a type of solid waste that is heavily influenced by consumers. The composition (%) and the total weight generation (kg) of food waste were determined during the Covid-19 outbreak. The data was obtained by direct weighing of the food waste collected where it was generated throughout the day. Findings have shown that 63.3% of the composition of uncooked food waste types identified is generated by internal organs, vegetables, fruits, and eggshells, while 36.7% of the identified composition of cooked food waste types is generated by rice and noodles, bones, vegetables, fruits, and others in Desa Pandan. During six days of collection, the total food waste generated by 30 households, 10 restaurants, and 3 schools was 146.5 kg (0.20 kg/capita/day), 231.7 kg (0.026 kg/capita/day), and 155.4 kg (0.010 kg/capita/day) respectively. A food waste awareness survey was conducted online with 100 respondents using Google Forms. Findings show that the Covid-19 pandemic did influence people's attitudes and practices regarding food purchase, management, and consumption habits, all of which have a substantial impact on reducing food waste generation at the household level.

Publication

A comprehensive review of the recent developments in wearable Sweat-Sensing Devices

( 2022-10-01)

Nur Fatin Adini Ibrahim

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Norhayati Sabani

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Shazlina Johari

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Asrulnizam Abd Manaf

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Asnida Abdul Wahab

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Zulkarnay Zakaria

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Anas Mohd Noor

Sweat analysis offers non-invasive real-time on-body measurement for wearable sensors. However, there are still gaps in current developed sweat-sensing devices (SSDs) regarding the concerns of mixing fresh and old sweat and real-time measurement, which are the requirements to ensure accurate the measurement of wearable devices. This review paper discusses these limitations by aiding model designs, features, performance, and the device operation for exploring the SSDs used in different sweat collection tools, focusing on continuous and non-continuous flow sweat analysis. In addition, the paper also comprehensively presents various sweat biomarkers that have been explored by earlier works in order to broaden the use of non-invasive sweat samples in healthcare and related applications. This work also discusses the target analyte’s response mechanism for different sweat compositions, categories of sweat collection devices, and recent advances in SSDs regarding optimal design, functionality, and performance.

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Publication

A Dual Approach on Experimental, Theoretical Insight of Structural Elucidation, Hirshfeld Surface Analysis, Optical and Electrochemical Properties of Acyl Thiourea-Ethynyl Hybrid Derivatives

( 2022-09-01)

Adibah Izzati Daud

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Khairul W.M.

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Arshad S.

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Razak I.A.

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González D.L.N.

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Erben M.F.

Hybrid moieties of ethynylated-thiourea, Th1 and Th2 have been synthesised via the addition reaction between ethynyl derivatives and 4-tert-butylbenzoyl isothiocyanate in acetone, and were characterised by selected spectroscopic methods (i.e., 1H and 13C NMR, UV–visible, FT-IR) and elemental analysis. Thermogravimetric analysis indicated that Th1 and Th2 were relatively stable up to ca. 210 °C. Single-crystal X-ray diffraction was used to identify the crystal structure of Th2 in which the centre of 1-acyl thiourea moiety (-C(O)NHC(S)NH) exhibits S conformation. The Hirshfeld surface analysis has allowed visualizing the crystal packing, which is characterised by the prolonged intermolecular N–H⋯O = C and N–H⋯S = C hydrogen-bonding interactions within Th2 molecule. Electrochemical data of both compounds correspondingly exhibit irreversible redox potential processes. Besides, frontier molecular orbitals and Natural Bond Orbital population analysis were computed at the B3LYP/6-31G (d, p) level of approximation, suggesting strong delocalization of the electronic density through a conjugated π-system involving the ethynyl-phenyl and thiourea groups. Graphical Abstract: Figure of molecular structure for acyl thiourea-ethynyl derivative. Two derivatives of acyl thiourea-ethynyl were synthesised and characterised by selected spectroscopic methods such as 1H and 13C NMR, UV-visible, FT-IR, elemental, thermal, electrochemical, X-ray diffraction, and density functional theory (DFT) calculation for molecular orbitals and natural bond orbital population analysis. [Figure not available: see fulltext.]

Publication

A Free-Space measurement system for microwave materials at Kuband

( 2022-01-01)

Sivakumar Renukka

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Lee Y.S.

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Saidatul Norlyana Azemi

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Zahari Awang Ahmad

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Jack Soh P.

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You K.Y.

One of the non-resonant techniques is the free-space measurement technique, which is popular due to its many advantages compared to the other techniques. It allows the transmission and reflection measurements without any physical contact with the sample. This paper discusses the free-space material measurement system in Ku-band which uses the NRW algorithm and Keysight (Formerly Agilent) 85071E software in determining the dielectric properties of materials. The permittivity and permeability of Teflon, FR4, PVC, ABS, Acrylic, polypropylene, polycarbonate, and epoxy were determined using free space measurement setup. For the first, a free-space measurement for Ku-Band is setup. It consists of a vector network analyzer, two horn antennas, sample holder, and Keysight 85071E software. The different role of transmission and reflection measurements on the achievable results is analyzed about experimental uncertainties and different noise scenarios. Results from the two strategies are analyzed and compared. Good agreement between simulation, measurement, and literature was obtained.

Publication

A Frequency-Reconfigurable Microstrip Antenna with Constant Dipole-Like Radiation Patterns Using Single Bias, Triple Varactor Tuning with Reduced Complexity

( 2022-03-01)

Hossain K.

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Soh Ping Jack

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R Badlishah Ahmad

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Jais M.I.

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Mohamed Nasrun Osman

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Hasliza A Rahim @ Samsuddin

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Saluja N.

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Abbasi Q.H.

This work proposes a novel frequency-reconfigurable circular patch antenna incorporated with a rectangular slot and a narrow slot capable of producing constant dipole-like radiation patterns. The antenna compactness is achieved with the integration of the rectangular slot defected ground structure (DGS) on the ground. The proposed antenna is able to perform continuous frequency tuning between 1.91 and 2.77 GHz with a frequency ratio of 1.5:1, in addition to stable dipole-like radiation patterns. The resonant frequency of the antenna is controlled by tuning a simple DC biasing network that consists of three RF varactor diodes located on the narrow slot DGS. Implementing the DC biasing network at the narrow slot DGS while maintaining the large slot DGS helps the antenna miniaturization and maintains the constant dipole-like radiation pattern over all frequency tuning range. The results are validated via simulations and experimental validations in terms of reflection coefficients and the radiation patterns. Measurements indicated that an impedance bandwidth of 85 MHz is featured for each tuned frequency band, with dipole-like patterns and an average gain of 1.57 dBi.

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Publication

A hybrid modified sine cosine algorithm using inverse filtering and clipping methods for low autocorrelation binary sequences

( 2022-01-01)

Rosli S.J.

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Hasliza A Rahim @ Samsuddin

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Khairul Najmy Abdul Rani

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Ruzelita Ngadiran

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Wan Azani Wan Mustafa

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Abdulmalek M.

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Wan Nur Suryani Firuz Wan Ariffin

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Alkhayyat A.

The essential purpose of radar is to detect a target of interest and provide information concerning the target's location, motion, size, and other parameters. The knowledge about the pulse trains' properties shows that a class of signals is mainlywell suited to digital processing of increasing practical importance. A low autocorrelation binary sequence (LABS) is a complex combinatorial problem. The main problems of LABS are low Merit Factor (MF) and shorter length sequences. Besides, the maximumpossibleMF equals 12.3248 as infinity length is unable to be achieved. Therefore, this study implemented two techniques to propose a new metaheuristic algorithm based on Hybrid Modified Sine Cosine Algorithm with Cuckoo Search Algorithm (HMSCACSA) using Inverse Filtering (IF) and clipping method to achieve better results. The proposed algorithms, LABS-IF and HMSCACSA-IF, achieved better results with two large MFs equal to 12.12 and 12.6678 for lengths 231 and 237, respectively, where the optimal solutions belong to the skew-symmetric sequences. TheMFoutperformed up to 24.335% and 2.708% against the state-of-the-art LABS heuristic algorithm, xLastovka, and Golay, respectively. These results indicated that the proposed algorithm's simulation had quality solutions in terms of fast convergence curve with better optimal means, and standard deviation.

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Publication

A hybrid multi-objective Evolutionary Programming-Firefly Algorithm for different type of Distributed Generation in distribution system

( 2022-12-01)

Noor Najwa Husnaini Mohammad Husni

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Siti Rafidah Abdul Rahim

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Mohd Rafi Adzman

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Hussain M.H.

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Musirin I.

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Syahrul Ashikin Azmi

With the rise in electricity demand, various additional sources of generation, known as Distributed Generation (DG), have been introduced to boost the performance of power systems. A hybrid multi-objective Evolutionary Programming-Firefly Algorithm (MOEPFA) technique is presented in this study for solving multi-objective power system problems which are minimizing total active and reactive power losses and improving voltage profile while considering the cost of energy losses. This MOEPFA is developed by embedding Firefly Algorithm (FA) features into the conventional EP method. The analysis in this study considered DG with 4 different scenarios. Scenario 1 is the base case or without DG, scenario 2 is for DG with injected active power, scenario 3 is for DG injected with reactive power only and scenario 4 is for DG injected with both active and reactive power. The IEEE 69-bus test system is applied to validate the suggested technique.

Publication

A Hybrid Optimization Approach for Power Loss Reduction and Voltage Profile Improvement in Distribution System

( 2022-01-01)

Noor Najwa Husnaini Mohammad Husni

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Siti Rafidah Abdul Rahim

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Mohd Rafi Adzman

In the past decades, the electrical power system is designed and developed to satisfy the owner demand that continuously appears in many variations. Hence, engineers have put their full effort to solve the problem associated with electrical power systems that come and might arise in the future. Therefore, distributed generation (DG) has been introduced to solve multiple electrical power system problems. The proposed methodology presented in this study focuses on minimizing network power losses, improving the voltage profile of system operation, and security constraints in a distribution. It is known that the location and capacity of DG play significant roles in the system losses in a distribution system. A hybrid metaheuristic nature-inspired algorithm is presented in this study for optimal location and sizing of multiple DG units. The best location and optimal sizing of DGs will be determined through Hybrid metaheuristic of Artificial Immune System Firefly Algorithm (AISFA). The designated technique will be tested into IEEE-69 test system using MATLAB software. For reducing the power losses, the simulation results have shown that bus 61 is the best location for reducing power losses and improving voltage profile in IEEE-69 test system in the preliminary result. By installing DG at bus 61, the real power losses improve about 89%, with a voltage profile improvement index up to 1.249099.

Publication

A new denoising method for removing salt & pepper noise from image

( 2022-01-01)

Charmouti B.

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Ahmad Kadri Junoh

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Abdurrazzaq A.

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Mohd Yusoff Mashor

Digital image has a significant importance in many fields in human life such as, in medicine, photography, biology, astronomy, industry and defense. Thus, it attracts the attention of large number of researchers, among them those interested in preserving the image features from any factors that may reduce the image quality. One of these factors is the noise. Thus far, solving this noise problem remains a challenge point for the researchers in this field, a huge number of image denoising techniques have been introduced in order to remove the noise with taking care of the image features (edges, sharpness). However, besides that, the findings proved to be inconclusive yet. From this point, the current paper aims to introduce a new denoising method for removing salt & pepper noise from the digital image through spatial way. This denoising method exploits the relationship between pixel’s values when the image changes color. Which gives ordered sequences of values in the four directions, horizontal, vertical and diagonals of the window. The proposed method relays on this concept to change the corrupted pixel, by using the neighbors in the window to extracts the truest value (subjects to this sequence) of the treated pixel. This method has been proven to be simple, effective and performing well comparing with the existing restoration methods with low computational cost.

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Publication

A new optimization strategy for wind/diesel/battery hybrid energy system

( 2022-01-15)

Aziz A.S.

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Mohammad Faridun Naim Tajuddin

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Hussain M.K.

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Mohd Rafi Adzman

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Nur Hafizah Ghazali

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Ramli M.A.M.

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Khalil Zidane T.E.

HOMER software is a powerful tool for modeling and optimization of hybrid energy system (HES). The main two default control strategies in HOMER are load following (LF) and cycle charging (CC) strategies. In these strategies, the decision to use the generator or battery at each time step is made based on the lowest-cost choice. Therefore, these strategies are difficult to be implemented in practice especially in countries with continuous fuel price fluctuations. In this study, a new dispatch strategy based on HOMER-MATLAB Link Controller for an isolated wind/diesel/battery HES is proposed to overcome the limitations of the default HOMER strategies. A detailed technical, economic, and greenhouse gas emission analysis is presented for the system under LF, CC, and the proposed dispatch strategies. Besides offering more realistic optimization, the results show that the proposed strategy offers the best economic and environmental performance with a net present cost of $56473 and annual CO2 emissions of 6838 kg. Furthermore, the sensitivity analysis reveals that the proposed strategy is not affected by the fuel price variation, in opposite to LF, and CC strategies which is affected dramatically by this variation. The findings are of paramount importance towards more realistic and efficient energy management strategies.

Publication

A novel unsupervised spectral clustering for pure-tone audiograms towards hearing aid filter bank design and initial configurations

( 2022-01-01)

Elkhouly A.

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Allan Melvin Andrew

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Hasliza A Rahim @ Samsuddin

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Abdulaziz N.

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Abdulmalek M.

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Siddique S.

The current practice of adjusting hearing aids (HA) is tiring and time-consuming for both patients and audiologists. Of hearing-impaired people, 40–50% are not satisfied with their HAs. In addition, good designs of HAs are often avoided since the process of fitting them is exhausting. To improve the fitting process, a machine learning (ML) unsupervised approach is proposed to cluster the pure-tone audiograms (PTA). This work applies the spectral clustering (SP) approach to group audiograms according to their similarity in shape. Different SP approaches are tested for best results and these approaches were evaluated by Silhouette, Calinski-Harabasz, and Davies-Bouldin criteria values. Kutools for Excel add-in is used to generate audiograms’ population, annotated using the results from SP, and different criteria values are used to evaluate population clusters. Finally, these clusters are mapped to a standard set of audiograms used in HA characterization. The results indicated that grouping the data in 8 groups or 10 results in ones with high evaluation criteria. The evaluation for population audiograms clusters shows good performance, as it resulted in a Silhouette coefficient >0.5. This work introduces a new concept to classify audiograms using an ML algorithm according to the audiograms’ similarity in shape.

Publication

A Novel V-shaped slotted single, dual band frequency reconfigurable antenna for C-band / 5G applications

( 2022-01-01)

Ganesh M.

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Srinivasa Nallanthighal R.

In this paper, a novel V-shaped slotted single, dual band frequency reconfigurable antenna is presented for upcoming 5G and C-band applications. The antenna operates around 3.9 GHz (5G), around 5.5 GHz Wireless Local Area Networks (WLAN) and 6.37 GHz for C-band applications. For obtaining the reconfigurability in the designed structure a V-shaped slot is etched on hexagonal shape radiating element and a PIN diode is adopted. If the PIN diode is ON state, the proposed radiating structure provides dual band operations in the frequency range of 3.49-4.46 GHz with centre frequency around 3.9 GHz and 5.59-7.59 GHz with centre frequency around 6.37 GHz with a bandwidth of 970 MHz, 2000 MHz respectively, else provides a single band operation in the frequency range of 4.03-7.14 GHz with centre frequency around 5.5 GHz with bandwidth of 3110 MHz. A hexagonal shape radiating patch element is incorporated on FR-4 substrate with overall size of (30 x 28 x 1.6) mm3. A comparative analysis with cutting edge work demonstrates that the presented designed antenna structure has the advantages of compact size, improved bandwidth and gain.

Publication

A Recent Systematic Review of Cervical Cancer Diagnosis: Detection and Classification

( 2022-09-01)

Wan Azani Wan Mustafa

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Alias N.A.

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Mohd Aminudin Jamlos

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Ismail S.

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Alquran H.

Women around the world are frequently diagnosed with cervical cancer. In the beginning, there are no symptoms for the fourth most common cause of fatality in women. Cells of cervical cancer develop gradually at the cervix. Several studies have mentioned that early detection of cervical tumor is very important for the cancer to be properly treated and to make sure the cancer can be successfully treated while minimizing deaths due to cervical cancer. The diagnosis of such cancer before it spread fast is currently a pressing issue for healthcare professionals. The systematic analysis has many benefits above conventional literature reviews. These evaluations can be improved by having a more defined review procedure, a more important topic of study, and fundamental priorities that can control research bias. This also provides a comprehensive understanding of the physical characteristics of the healthy and unhealthy cervix and aids in early treatment planning by giving detailed information about one another. Utilizing image segmentation, a number of techniques are employed to find malignancy. The dataset contains four distinct pathological pictures, including normal, malignancy, and high-grade squamous intraepithelial lesions (HSIL). While pap tests are the most popular way to diagnose cervical cancer, their accuracy depends a lot on how well cytotechnicians can use brightfield microscopy to spot abnormal cells on smears.

Publication

A Review of Circularly Polarized Dielectric Resonator Antennas: Recent Developments and Applications

( 2022-12-01)

Abd Rahman N.A.

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Ibrahim I.M.

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Noor S.K.

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Ekscalin Emalda Mary M.R.

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Zamin N.

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Nurhayati N.

A comprehensive review on recent developments and applications of circularly polarized (CP) dielectric resonator antennas (DRAs) is proposed in this paper. DRAs have received more considerations in various applications due to their advantages such as wide bandwidth, high gain, high efficiency, low losses, and low profile. A broad justification for circular polarization and DRAs is stated at the beginning of the review. Various techniques such as single feed, dual, or multiple feeds used by different researchers for generating circular polarization in DRAs are briefly studied in this paper. Multiple-input-multiple-output (MIMO) CP DRAs, which can increase channel capacity, link reliability, and data rate, have also been analyzed. Additionally, innovative design solutions for broadening the circular polarization bandwidth and reducing mutual coupling are studied. Several applications of DRA are also discussed comprehensively. This paper finishes with concluding remarks.

Publication

A Review of Orbital Angular Momentum Vortex Waves for the Next Generation Wireless Communications

( 2022-01-01)

Noor S.K.

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