Design of a Power Factor Measurement System for Nonlinear Load

Shahriar, Md. Rifat,Chong, Ui-Pil The Korean Institute of IIIuminating and Electrica 2011 조명·전기설비학회논문지 Vol.25 No.11

This paper introduces and develops an efficient method for measuring power factor (PF) and its nature under nonlinear load current situations. The method is based on generating a pulse width modulated signal whose width correlates to the value of PF. This signal can then be employed as a feedback signal for controlling PF related power quantities in a system. This method has the advantages of its simple implementation, less computational complexity, and its allowable error of less than 4[%], which is justified by the computer simulation results.

Improving seismic performance of eight-bolt extended end plate moment connection

Shahriar Quayyum,Timothy R. Kohany 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.3

The eight-bolt stiffened extended end plate (8ES) connection is one of the connections prequalified for use in special and intermediate moment frames in ANSI/AISC 358. Simulated seismic testing of 8ES connections has generally shown sound performance with ductile failure modes. However, fast fracture of the beam flange at the stiffener toe has been observed in a recent study and was attributed to the high stress concentration in this region. To address this problem, an unstiffened eight-bolt extended end plate connection in which the stress concentration is eliminated by removing the stiffener, and the bolts are rearranged into an octagonal pattern to ensure uniform distribution of bolt forces, has been recently proposed. The study herein performed detailed finite element analyses with octagonal bolt arrangement to demonstrate that despite the improvements, high strain demands at the beam flange to end plate CJP welds may develop when the proposed unstiffened connection is used in conjunction with deep wide flange beam sections (e.g., W-sections of 900 mm nominal depth). Hence, an extended shear tab is used and analytically evaluated for unreinforced eight-bolt extended end plate connections. The extended heavy shear tab relocates the plastic hinge away from flange weld and slightly delays the onset of strength degradation. Systematic analysis results are developed and presented to demonstrate the enhanced seismic performance of the modified EEP connections and to plan future experimentations and design development.

Integrating oversampling and ensemble-based machine learning techniques for an imbalanced dataset in dyslexia screening tests

Shahriar Kaisar,Abdullahi Chowdhury 한국통신학회 2022 ICT Express Vol.8 No.4

Developmental Dyslexia is a learning disorder often discovered in school-aged children who face difficulties while reading or spelling words even though they may have average or above-average levels of intelligence. This ultimately results in anger, frustration, low self-esteem, and other negative feelings. Early detection of Dyslexia can be highly beneficial for dyslexic children as their learning needs can be properly addressed. Researchers have used several testing techniques for early discovery where the data is collected from reading and writing tests, online games, Magnetic reasoning imaging (MRI) and Electroencephalography (EEG) scans, picture and video recording. Several Machine learning techniques have also been used in this regard recently. However, existing works did not focus on the problem of the imbalanced dataset where the percentage of dyslexic participants is much higher compared to non-dyslexic participants, which is expected to be the case for pre-screening among a random population. This paper addresses the imbalanced dataset obtained from dyslexia pre-screening tests and proposes an oversampling and ensemble-based machine learning technique for the detection of Dyslexia. Simulation results show that the proposed approach improves the detection accuracy of the minority class, i.e., dyslexic patients from 80.61% to 83.52%.

Optimal 3D UAV Base Station Placement by Considering Autonomous Coverage Hole Detection, Wireless Backhaul and User Demand

Shahriar Abdullah Al-Ahmed,Muhammad Zeeshan Shakir,Syed Ali Raza Zaidi 한국통신학회 2020 Journal of communications and networks Vol.22 No.6

The rising number of technological advanced devicesmaking network coverage planning very challenging tasks for network operators. The transmission quality between the transmitterand the end users has to be optimum for the best performance outof any device. Besides, the presence of coverage hole is also an ongoing issue for operators which cannot be ignored throughout thewhole operational stage. Any coverage hole in network operators’coverage region will hamper the communication applications anddegrade the reputation of the operator’s services. Presently, thereare techniques to detect coverage holes such as drive test or minimization of drive test. However, these approaches have many limitations. The extreme costs, outdated information about the radioenvironment and high time consumption do not allow to meet therequirement competently. To overcome these problems, we take advantage of Unmanned aerial vehicle (UAV) and Q-learning to autonomously detect coverage hole in a given area and then deployUAV based base station (UAV-BS) by considering wireless backhaul with the core network and users demand. This machine learning mechanism will help the UAV to eliminate human-in-the-loop(HiTL) model. Later, we formulate an optimisation problem for3D UAV-BS placement at various angular positions to maximisethe number of users associated with the UAV-BS. In summary, wehave illustrated a cost-effective as well as time saving approach ofdetecting coverage hole and providing on-demand coverage in thisarticle.

The Impact of COVID-19 on Bangladesh's Economy: A Focus on Graduate Employability

SHAHRIAR, Mohammad Shibli,ISLAM, K.M. Anwarul,ZAYED, Nurul Mohammad,HASAN, K.B.M. Rajibul,RAISA, Tahsin Sharmila Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.3

The COVID-19 pandemic is having an adverse impact on Bangladesh's economy by affecting millions of people's life and hampering their income sources. The outbreak of COVID-19 has created more pressure on the labor market. The pandemic reduces employment opportunities as most of the companies have stopped their recruitment process to cut their operational costs, which increases the rate of graduate unemployment in Bangladesh. Hence, this study aims to investigate the impact of COVID-19 on graduate employability in Bangladesh that adversely affects the income of families and eventually the nation's economy. A literature review has been conducted from secondary sources to evaluate the impact, which shows that the rate of graduate unemployment increased from 47% to 58% in 2020 with an expected annual loss estimated at $53 million. Findings also reveal that the prime reasons for graduate employability are low demand and huge supply of graduates in the labor market, lack of professional skills of graduates, ineffective education system, etc. The study suggests that the government of Bangladesh should develop some policies to overcome this problem such as ensuring employment subsidies, implementing skills development programs, improving labor market flexibility, initiating credit programs for generating employment, and developing entrepreneurial ecosystems in Bangladesh.

Challenges of user Involvement in Extreme Programming projects

Shahriar Mohammadi,Bahman Nikkhahan,Sahar Sohrabi 보안공학연구지원센터 2009 International Journal of Software Engineering and Vol.3 No.1

Extreme programming (XP) is one of the most frequently used methodologies in Agile Software Development. According to various reports it had a significant effect on the software projects that use XP. In this paper, one of the main practices of XP, called "on-site customer" is considered, in detail. Also, various important challenges related to its implementation are considered. In each case, according to reports and researches related to user involvement, suitable solutions for resolving the problems are offered. At the end of each case, having an appropriate alternative that uses "Product Management Team" is proposed.

Developmental dyslexia detection using machine learning techniques : A survey

Shahriar Kaisar 한국통신학회 2020 ICT Express Vol.6 No.3

Developmental dyslexia is a learning disability that occurs mostly in children during their early childhood. Dyslexic children face difficulties while reading, spelling and writing words despite having average or above-average intelligence. As a consequence, dyslexic children often suffer from negative feelings, such as low self-esteem, frustration, and anger. Therefore, early detection of dyslexia is very important to support dyslexic children right from the start. Researchers have proposed a wide range of techniques to detect developmental dyslexia, which includes game-based techniques, reading and writing tests, facial image capture and analysis, eye tracking, Magnetic reasoning imaging (MRI) and Electroencephalography (EEG) scans. This survey paper critically analyzes recent contributions in detecting dyslexia using machine learning techniques and identify potential opportunities for future research.

Self-powered Flexible PDMS Channel Assisted Discrete Liquid Column Motion Based Triboelectric Nanogenerator (DLC-TENG) as Mechanical Transducer

Shahriar, M.,Vo, Cong Phat,Ahn, Kyoung Kwan SPRINGER 2019 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND Vol. No.

Characterization of bare and modified nano-zirconium oxide (ZrO2) and their applications as adsorbents for the removal of bivalent heavy metals

Shahriar Mahdavi,Nadereh Amini,Hajar Merrikhpour,Davoud Akhzari 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1

The ability of nano-ZrO2 and modified nano-ZrO2 with humic acid (ZrO2-H) to remove Cd2+, Cu2+ and Ni2+ from aqueous media has been tested by batch sorption studies varying the contact time, initial metal concentration, initial solution pH, sorbent dosage and temperature to understand the adsorption behavior of these metals through adsorption kinetics and isotherms. The bare nanoparticles (NPs) and modified NPs (MNPs) were characterized using X-ray powder diffraction (XRD), SEM-EDX, FTIR to determine the phase, average grain size, morphology, surfacial elemental compounds and functional groups of NPs and MNPs. The pH of the solutions and the temperature controlled the adsorption of metal ions by NPs and MNPs as well as maximum uptake occurred in the first 120min of reaction in almost all metals. The kinetics of adsorption followed a pseudo-second-order rate equation (R2>0.97) and the isotherms were well described by the Freundlich model in Cd2+ and Cu2+, but in Ni2+ isotherms were better described by Langmuir model. The adsorption of metals onto almost all NPs and MNPs were spontaneous and endothermic in nature. Among the three metals, Cd2+ showed more preference towards the sites on ZrO2 and ZrO2-H than Cu2+ and Ni2+. This study reveals that ZrO2 and ZrO2-H are effective adsorbents in removing Cd2+, Cu2+ and Ni2+ from the aqueous environment with an adsorptive capacity of 46.2, 59.7, 39.5, 29.7, 9.2 and 16.7mg·g−1, respectively.

Synthesis and Characterization of Two New Fluoroplumbate(II) Complexes: Tetrabutylammonium Fluorodihaloplumbate, (But)4N[PbX2F] (X = Cl, I)

Shahriare Ghammamy,Zahra Javanshir,Kheyrollah Mehrani,LotfAli Saghatforoush,Seyedabolfazl Seyedsadjadi,Ali Hassanijoshaghani 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.8

Tetrabutylammonium Fluorodichloroplumbate(II), N(C4H9)4[PbCl2F], TBAFDiCP and Tetrabutylammonium Fluorodiiodoplumbate(II), [(C4H9)4N][PbI2F], TBAFDiIP are the first examples of fluoroplumbate salts that have been prepared from the reaction of (C4H9)4NF with PbCl2 and PbI2 respectively using either CH3CN solvent. These new compound characterized by elemental analysis, IR, UV/Visible, 1H NMR, and 19F NMR techniques.