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.

Influence of Toll pathway on eicosanoid signal in Spodoptera exigua (Lepidoptera: Noctuidae)

Tahir Shafeeq,Yonggyun Kim 한국응용곤충학회 2017 한국응용곤충학회 학술대회논문집 Vol.2017 No.10

An immune signal pathway using Toll receptor in response to Gram positive bacterial or fungal challenge induces cellularimmunity and production of antimicrobial peptides (AMPs) in insects. Here we tested an hypothesis that Toll signal downstreamfactors, MyD88 and Pelle, influence eicosanoid signal by activating phospholipase A2 (PLA2) activity in the beet armywormSpodoptera exigua. We knocked-down MyD88 and Pelle expressions using specific dsRNAs and assessed their effect onPLA2 activity in immune-challenged S. exigua larvae. The RNAi-treated larvae failed to induce AMP gene expressionand PLA2 activity under immune challenge. These results shed light on cross-talk between Toll pathway and eicosanoidsignal.

Pathologies of Technology Transfer and Commercialization in South Korea

Tahir Hameed,PeterVonStaden,Ki-Seok Kwon 한국기술혁신학회 2017 한국기술혁신학회 학술대회 발표논문집 Vol.2017 No.5

The paper tests the above socio-cognitive model with four empirical case studies of leading Korean science and technology research and technology transfer organizations. The case studies demonstrate clear differences in individuals’ frames about the technology transfer process and arising conflicts. As a result, technology transfer process is not fully controllable and is highly contextual. We argue, whereas public policy in countries approaching technology frontier provides essential support for defining and exploiting best practices (routines/pathways) for technology transfer at organizational level, they have not matured enough to support the timely identification and resolution of conflicts between individual actors, hence the inefficiencies. Therefore, among others, public policy for technology transfer could consider allowing an inclusive approach to recognition of best practices for technology transfer and innovation processes, increased social interactions between technology transfer actors, and their training on resolution of individual level cognitive conflicts.

Corporate Board Attributes and Dividend Pay-out Policy: Mediating Role of Financial Leverage

TAHIR, Hussain,MASRI, Ridzuan,RAHMAN, Mahfuzur Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.1

The relationship between corporate board attributes and dividend payout is already established yet mediating role of leverage in not been examined in Malaysian market. Therefore, this study aims to examine the mediating effect of financial leverage on the relationship between corporate board attributes and the dividend pay-out policy. A sample of 203 non-financial firms listed on the BURSA Malaysia between 2005 and 2018 were analysed using SmartPLS 3.0. The findings show that there is a partial mediating effect of financial leverage on the relationship between board members age, board diversity and dividend pay-out policy. Financial leverage also mediates the relationship between number of women on board, CEO-duality and dividend pay-out policy. However, financial leverage doesn't mediate the relationship between board size and dividend pay-out policy. This study offers insights to policy-makers to develop a better corporate governance as well as a guidance to firms in the construction and implementation of their corporate governance policies in relation to financial leverage. This study also shed light on the influence of efficient corporate board attributes on dividend pay-out policy and financial leverage for firm growth. This study concludes that corporate board attributes impact capital structure and thus, firms may change its payout policy.

Extraordinary optical transmission: Role of the slit width in 1D metallic grating on higher refractive index substrate

Tahir Iqbal,Sumera Afsheen 한국물리학회 2016 Current Applied Physics Vol.16 No.4

We present a detailed analysis of the excitation of surface plasmon polaritons (SPPs) and associated extraordinary optical transmission (EOT) when a plane wave is incident at normal on a 1D metallic grating fabricated on higher refractive index GaP substrate. A simple method is introduced to estimate the EOT by measuring the 0th order transmission spectra obtained through the plasmonic grating structures with varying grating slit width for a fixed period and the thickness of the gold (Au) film in which the grating is formed. For an optimum Au film thickness, a slit width of slightly less than half and greater than one-third of the periodicity of 770 nm in the grating device yields a maximum EOT value. Such grating devices support only a fundamental plasmonic mode because the profile/shape of the slit in the grating device is more like a sinusoidal nature. Far-field and near-field modelling results also support the far-field results obtained through the experiment. The optimal grating devices have many applications in real world.

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.

Analysis of the whole developmental period reveals stage-specific gene expression profiles of the Indianmeal moth, Plodia interpunctella

Tahir Shafeeq,차상목,심재경,이경열 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

The Indianmeal moth, Plodia interpunctella, is a global pest of stored and processed food products. Although its biology and management have been widely studied, there is limited information on the roles of specific genes during development at the molecular level. To get better understanding of physiological roles of each gene underlying in insect development, it is necessary to determine the precise and comprehensive profiles of each gene throughout development. Here, we determined the whole developmental expression patterns of 13 genes related to growth, stress, metabolism, and host defense by using quantitative real-time RT-PCR. Our results showed that the expression profiles of the 13 genes were unique throughout the development of P. interpunctella. Expression levels of stress-associated genes such as heat-shock protein genes (hsps) and an antioxidant gene, thioredoxin peroxidase (Tpx), were highest in both egg and adult stages. Expression levels of both ecdysone receptor (EcR) and ultraspiracle (USP) were differentially the highest in the pupal and wandering phase of the fifth instar larvae, respectively. Expression levels of immune-related genes such as hemolin and β-1,3 glucan recognition protein (βgrp) were the highest during the wandering larval and pupal stages, while those of prophenoloxidase (ProPO), superoxide dismutase (SOD), and two storage protein genes (SP1 and SP2) were the highest during the wandering larval stage. This study provides comprehensive insights for understanding the functional roles of genes especially hsps and Tpx, which are stage-specifically regulated during the development of P. interpunctella.

The Influence of Freezing-Thawing Cycles on The Capillary Water Absorption and Porosity of Concrete with Mineral Admixture

Tahir Gonen,Salih Yazicioglu,Bahar Demirel 대한토목학회 2015 KSCE Journal of Civil Engineering Vol.19 No.3

The main objective of this experimental study is to determine which of the effective parameter among ultrasonic pulse velocity,compressive strength, capillary water absorption and porosity during freezing and thawing on concrete produced with mineraladmixtures. The specimens were exposed to 25, 50, 75 and 100 freezing-thawing cycles after 28 curing days. The results showed thatamong the measured parameters, capillary water absorption was the most affected parameter from freeze-thaw cycles.