Experimental Tests on Extended End-Plate Connections with Variable Parameters

Mahmood Md Tahir1,Md Azman Hussein 한국강구조학회 2008 International Journal of Steel Structures Vol.8 No.4

Typically, steel frames are designed either using the approach of pin joint for simple construction or rigid joint for continuous construction. However, in actual situation most of connections are classified as semi-rigid joint or partial strength which has been recognised and encouraged by Eurocode 3 in semi-continuous construction. Eight experimental tests have been carried out for extended end-plate connections consist of variable parameters such as size and thickness of end-plate, size and number of bolts, size of columns, and beams. The tests were set-up using local hot-rolled steel sections known as Perwaja sections for both beams and columns instead of typical British sections. Geometric parameters such as the thickness of end-plate, the number and size of bolts and the use of deeper beam have contributed significantly to the increase in moment resistance and stiffness of the connections. The study concluded that all the tested extended end-plate connections are eligible to be classified as partial strength connections and the results of maximum moment resistance showed good agreement between experimental and predicted component method in most cases.

Stock Market Response to Terrorist Attacks: An Event Study Approach

TAHIR, Safdar Husain,TAHIR, Furqan,SYED, Nausheen,AHMAD, Gulzar,ULLAH, Muhammad Rizwan Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9

The purpose of this research study is to examine the stock market's response to terrorist attacks. The study uses data of terrorist attacks in different parts of the country (Pakistan) from June 1, 2014 to May 31, 2017. The event window procedure applies to a 16-day window in which 5 days before and 10 days after the attack. In addition, several event windows have been built to test the response of the Pakistan Stock Exchange. KSE-100 index is taken as proxy of response. The total terrorist attacks are classified into four categories: attacks on law enforcement agencies, attacks on civilians, attacks on special places and attacks on politicians, government employees and bureaucrats. The standard market model is used to estimate the abnormal return of the Pakistan Stock Exchange, which takes 252 business days each year. Furthermore, BMP test is used to check statistical significance of cumulative abnormal rate of return (CAAR). The results of this study reveal that total number of terrorist attacks and attacks on law enforcement agencies show long-term effects on Pakistan stock exchange. However, attacks on civilians, attacks on special places and attacks on politicians, government employees and bureaucrats have little effect on the Pakistan Stock Exchange.

Privacy-preserving COVID-19 Contact Tracing using Blockchain

Shahzaib Tahir,Hasan Tahir,Ali Sajjad,Muttukrishnan Rajarajan,Fawad Khan 한국통신학회 2021 Journal of communications and networks Vol.23 No.5

The outbreak of the COVID-19 virus has causedwidespread panic and global initiatives are geared towards treatmentand limiting its spread. With technological advancements,several mechanisms and mobile applications have been developedthat attempt to trace the physical contact made by a personwith someone who has been tested COVID-19 positive. Whiledesigning these apps, user’s privacy has been an afterthoughtand has resulted in mass violations of privacy of the public andthe patients. A total of 32 countries have designed apps andrely on them as a strategy to flatten the pandemic curve. Alongwith lack of privacy, these methodologies are centralized, wherethey are fully controlled by the government and the healthcareproviders. Owing to these and many other concerns, peopleare hesitant in the adoption of these technologies. This paperpresents a detailed analysis of user tracking apps belongingto 32 countries, thus demonstrating that they collect personaldata and are a gross violation of user privacy. This paperpresents a novel architecture for the efficient, effective andprivacy-preserving contact tracing of COVID-19 patients usingblockchain. The proposed architecture preserves the privacy ofindividuals and their contact history by encrypting all the dataspecific to an individual using a privacy-preserving Homomorphicencryption scheme and storing it on a permissioned blockchainnetwork. The contacts made with a COVID-19 positive patientare identified by performing search queries directly over theHomomorphic encrypted data stored in the blocks. Therefore,only those contacts that are suspected to be COVID-19 positivemay be decrypted by the healthcare professional or governmentfor further contact tracing/ diagnosis and COVID-19 testing;thereby leading to enhanced privacy.

Electronic and optical properties of GIZO thin film grown on SiO₂/Si substrates

Tahir, Dahlang,Lee, Eun Kyoung,Kwon, Hyuk Lan,Kun Oh, Suhk,Kang, Hee Jae,Heo, Sung,Lee, Eun Ha,Chung, Jae Gwan,Lee, Jae Cheol,Tougaard, Sven John Wiley Sons, Ltd. 2010 Surface and interface analysis Vol.42 No.6

<P>The electronic and optical properties of GaInZnO (GIZO) thin films grown on SiO<SUB>2</SUB>/Si by r.f. magnetron sputtering were obtained by means of XPS and reflection electron energy loss spectroscopy (REELS). The optical properties represented by the dielectric function ϵ, refractive index n, extinction coefficient k and transmission coefficient T of GIZO thin films were obtained from a quantitative analysis of the REELS spectra. When the concentration ratios of Ga:In:Zn in GIZO thin films are 1:1:1, 2:2:1, 3:2:1 and 4:2:1, the bandgap values are 3.2, 3.2, 3.4 and 3.6 eV, respectively. The optical properties were determined from the energy loss of the REELS spectra by using quantitative analysis of electron energy loss spectra (QUEELS)-ϵ(k, ω)-REELS software. The optical properties depend on the Ga concentration, and the transmission in the visible region improved with increasing Ga concentration in GIZO. Copyright © 2010 John Wiley & Sons, Ltd.</P>

Source parameters for small–moderate earthquakes in Marmara Region (Turkey)

Tahir Serkan Irmak,Evrim Yavuz,Hamdullah Livaoğlu,Erman Şentürk,Emre Y. Sahin 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.5

The main aim of this study is to investigate the self-relation and self-similarity of earthquakes in and around the Marmara Sea (NW Turkey) by using these obtained source parameters. With this purpose, spectral source parameters for 77 small to moderate earthquake (3.5 ≤ ML ≤ 5.2) that occurred during 2004–2018 have been determined from P and S wave spectra according to Brune’s source model by using regional broadband seismograms. The average ratio of P/S wave corner frequency is found to be 1.3 that suggesting higher corner frequency for P wave. The static stress drops range from 0.1 and 136 MPa with a median value of 9.8 MPa (98 bars). The high stress drops for these events can indicate high frictional strength and low strain-rate of the faults. Similarly, the low values of the stress drop can indicate a general weakness of the faults in the study area. There is no clear dependence between the seismic moment and the static stress drop in the analyzed events but some events which have lower seismic moment value also have lower stress drop. Obtaining results indicated the corner frequency decreases with increasing of the seismic moment. Also, a slight depth dependence of the corner frequency has been observed for the analyzed events. Shallower events have larger corner frequency value than deeper events. Also, a clear depth dependence of the stress drop values has not been observed. However, the depth dependence of the seismic moment is seen more clearly. Our results indicated that the deeper events have larger seismic moment values in the study area. In spite of scattering in small events, a linear relationship between local magnitude (ML) and moment magnitude (MW) could be obtained as MW = 1.4261(± 0.31) + 0.6399(± 0.08)ML from P waves spectra and MW = 0.0136(± 0.21) + 0.9883(± 0.05)ML from S wave spectra and calculated MW values are consistent with waveform inversion (centroid moment tensor – CMT) results. These relationships may be useful for seismic hazard studies in the study area.

A SUBCLASS OF ANALYTIC FUNCTIONS DEFINED BY USING MITTAG-LEFFLER FUNCTION

( Tahir Mahmood ),( Muhammad Naeem ),( Saqib Hussain ),( Shahid Kjan ),( Şahsene Altinkaya ) 호남수학회 2020 호남수학학술지 Vol.42 No.3

In this paper, new subclasses of analytic functions are proposed by using Mittag-Leffler function. Also some properties of these classes are studied in regard to coefficient inequality, distortion theorems, extreme points, radii of starlikeness and convexity and obtained numerous sharp results.

UV-oxidative Treatment of Bio-refractory Organic Halogens In Leachate: Comparison between UV/O3, UV/H2O2, and UV/H2O2/O3 Processes

Tahir Imran Qureshi,Young Ju Kim 대한환경공학회 2006 Environmental Engineering Research Vol.11 No.2

Exploiting W. Ellison model for seawater communication at gigahertz frequencies based on world ocean atlas data

Tahir, Muhammad,Ali, Iftikhar,Yan, Piao,Jafri, Mohsin Raza,Jiang, Zexin,Di, Xiaoqiang Electronics and Telecommunications Research Instit 2020 ETRI Journal Vol.42 No.4

Electromagnetic (EM) waves used to send signals under seawater are normally restricted to low frequencies (f) because of sudden exponential increases of attenuation (𝛼) at higher f. The mathematics of EM wave propagation in seawater demonstrate dependence on relative permeability (𝜇_r), relative permittivity (𝜀_r), conductivity (𝜎), and f of transmission. Estimation of 𝜀_r and 𝜎 based on the W. Ellison interpolation model was performed for averaged real-time data of temperature (T) and salinity (S) from 1955 to 2012 for all oceans with 41 088 latitude/longitude points and 101 depth points up to 5500 m. Estimation of parameters such as real and imaginary parts of 𝜀_r, 𝜀_r', 𝜀_r", 𝜎, loss tangent (tan 𝛿), propagation velocity (V_p), phase constant (𝛽), and α contributes to absorption loss (L_a) for seawater channels carried out by using normal distribution fit in the 3 GHz-40 GHz f range. We also estimated total path loss (L_PL) in seawater for given transmission power P_t and antenna (dipole) gain. MATLAB is the simulation tool used for analysis.

LATTICE ORDERED FUZZY SOFT GROUPS

( Tahir Mahmood ),( Naveed Ahmad Shah ) 호남수학회 2018 호남수학학술지 Vol.40 No.3

In several _elds the soft set theory has a very vast range uses and applications. A soft group is a proper family of subgroups and a fuzzy soft group is a proper family of fuzzy subgroups. Here in this paper the concept of lattice ordered fuzzy soft groups is introduced. Also its some properties are studied and discussed. In addition, the de_ntion of lattice order fuzzy soft right (left) cosets and lattice order soft product of fuzzy soft subgroups and some related results are discussed to clear these ideas.

Optimization of Time Dial Settings for Coordination of Numerical Relays using Firefly Algorithm

Tahir Khurshaid,Sang-Bong Rhee 대한전기학회 2019 대한전기학회 학술대회 논문집 Vol.2019 No.10