Analysis of weld-induced residual stresses and distortions in thin-walled cylinders

Naeem Ullah Dar,Ejaz M. Qureshi,M.M.I Hammouda 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.4

Circumferential weld specifically in thin-walled structures is a common joint type in the fabrication of structural members in aerospace, aeronautical and pressure vessel industries. This type of weld joint suffers various types of weld-induced residual stress fields (hoop and axial) and deformation patterns (axial shrinkage, radial shrinkage). These imperfections have negative effects on fabrication accuracies and result in low strength welded structures that can lead to premature failures. To precisely capture the distortions and residual stresses, computational methodology based on three-dimensional finite element model for the simulation of gas tungsten arc welding in thin-walled cylinders is presented. Butt-weld geometry with single "V" for a 300 mm outer diameter cylinder of 3 mm thick is used. The complex phenomenon of arc welding is numerically solved by sequentially coupled transient, non-linear thermo-mechanical analysis. The accuracy of both the thermal and structural models is validated through experiments for temperature distribution, residual stresses and distortion. The simulated result shows close correlation with the experimental measurements.

The Nexus between Islamic Label and Firm Value: Evidence from Cross Country Panel Data

Naeem ULLAH,Abdul WAHEED,Nida AMAN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4

This research uses a panel data set of selected developed and emerging economies to investigate the relationship between firm value and the Islamic label. A low-debt company is a proxy for excellent governance, and good governance has a significant positive impact on a company’s valuation. We can claim that the Islamic label may also be a proxy for excellent governance and will significantly impact a company’s economic value because it reflects low debt Sharia-compliant companies. To explore this relationship, cross-country data from non-financial enterprises in Pakistan, the United States, Malaysia, and Indonesia was acquired from 2010 to 2015. The study’s findings indicate that the Islamic label has a positive significant impact on the firm’s worth in the whole sample, including all countries. With the exception of the United States, we have also collected the same information at the country level. We also discovered that the corporate governance index at the firm level has a positive significant impact on firm value. The findings show that the Islamic label reflects good governance and hence can be used as a proxy for good governance. The analysis differentiates between Islamic labeled and conventional enterprises in developed and emerging nations, adding to our understanding of who contributes to enhanced corporate financial performance.

A Cross-Platform Malware Variant Classification based on Image Representation

( Hamad Naeem ),( Bing Guo ),( Farhan Ullah ),( Muhammad Rashid Naeem ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.7

Recent internet development is helping malware researchers to generate malicious code variants through automated tools. Due to this reason, the number of malicious variants is increasing day by day. Consequently, the performance improvement in malware analysis is the critical requirement to stop the rapid expansion of malware. The existing research proved that the similarities among malware variants could be used for detection and family classification. In this paper, a Cross-Platform Malware Variant Classification System (CP-MVCS) proposed that converted malware binary into a grayscale image. Further, malicious features extracted from the grayscale image through Combined SIFT-GIST Malware (CSGM) description. Later, these features used to identify the relevant family of malware variant. CP-MVCS reduced computational time and improved classification accuracy by using CSGM feature description along machine learning classification. The experiment performed on four publically available datasets of Windows OS and Android OS. The experimental results showed that the computation time and malware classification accuracy of CP-MVCS was higher than traditional methods. The evaluation also showed that CP-MVCS was not only differentiated families of malware variants but also identified both malware and benign samples in mix fashion efficiently.

Impact of Teachers’ Professional Development on Students’ Performance

Mahwish Parveen,Obaid Ullah,Muhammad Salam,Naeem Zakir 한국유통과학회 2014 The Journal of Industrial Distribution & Business( Vol.5 No.3

Purpose - This study was conducted to identify the impact of teachers’ professional development on students’ performance. It examines the nature of association between teachers’ professional development and students’ performance, and analyzes how students can be affected by different factors of teachers’ professional development. Research design, data, and methodology - In order to obtain the required goals, Data were randomly collected from 100 students and 45 teachers from three different institutes that are affiliated with KPK Agriculture University, Peshawar. To test the association between teachers’ professional development and students’ performance, the Chi-square test was applied. Gamma measurement was computed to check the direction of association. Results - The results of the study supported the statement that there exists a positive relationship between teachers’ professional development and students’ performance. Conclusion - Based on the findings it is surmised that, in order to create a clear learning relationship between teachers and students, management must support the teachers through peer group discussions and training opportunities, and should chooseteachers who can make students pursue the learning of subject knowledge with practical implementation

Cadmium Accumulation and Antioxidant Response of Wheat Cultivars to Silicon Application in Hydroponics

Asif Naeem,Saif Ullah,Muhammad Zia Ur Rehman,Tasneem Akhtar 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Improved Physical Layer Implementation of VANETs

Khan, Latif Ullah,Khattak, M. Irfan,Khan, Naeem,Khan, Atif Sardar,Shafi, M. The Institute of Electronics and Information Engin 2014 IEIE Transactions on Smart Processing & Computing Vol.3 No.3

Vehicular Ad-hoc Networks (VANETs) are comprised of wireless mobile nodes characterized by a randomly changing topology, high mobility, availability of geographic position, and fewer power constraints. Orthogonal Frequency Division Multiplexing (OFDM) is a promising candidate for the physical layer of VANET because of the inherent characteristics of the spectral efficiency and robustness to channel impairments. The susceptibility of OFDM to Inter-Carrier Interference (ICI) is a challenging issue. The high mobility of nodes in VANET causes higher Doppler shifts, which results in ICI in the OFDM system. In this paper, a frequency domain com-btype channel estimation was used to cancel out ICI. The channel frequency response at the pilot tones was estimated using a Least Square (LS) estimator. An efficient interpolation technique is required to estimate the channel at the data tones with low interpolation error. This paper proposes a robust interpolation technique to estimate the channel frequency response at the data subcarriers. The channel induced noise tended to degrade the Bit Error Rate (BER) performance of the system. Parallel concatenated Convolutional codes were used for error correction. At the decoding end, different decoding algorithms were considered for the component decoders of the iterative Turbo decoder. A performance and complexity comparison among the various decoding algorithms was also carried out.

Design, Fabrication and Measurement of a Compact, Frequency Reconfigurable, Modified T-shape Planar Antenna for Portable Applications

Iqbal, Amjad,Ullah, Sadiq,Naeem, Umair,Basir, Abdul,Ali, Usman The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.8 No.1

This paper presents a compact reconfigurable printed monopole antenna, operating in three different frequency bands (2.45 GHz, 3 GHz and 5.2 GHz), depending upon the state of the lumped element switch. The proposed multiband reconfigurable antenna is designed and fabricated on a 1.6 mm thicker FR-4 substrate having a relative permittivity of 4.4. When the switch is turned ON, the antenna operates in a dual band frequency mode, i.e. WiFi at 2.45 GHz (2.06-3.14 GHz) and WLAN at 5.4 GHz (5.11-5.66 GHz). When the switch is turned OFF, it operates only at 3 GHz (2.44-3.66 GHz). The antenna radiates omni-directionally in these bands with an adequate, bandwidth (>10 %), efficiency (>90 %), gain (>1.2 dB), directivity (>1.7 dBi) and VSWR (<2). The fabricated antenna is tested in the laboratory to validate the simulated results. The antenna, due to its reasonably compact size ($39{\times}37mm^2$), can be used in portable devices such as laptops and iPads.

Design, Fabrication and Measurement of a Compact, Frequency Reconfigurable, Modified T-shape Planar Antenna for Portable Applications

Amjad Iqbal,Sadiq Ullah,Umair Naeem,Abdul Basir,Usman Ali 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4

This paper presents a compact reconfigurable printed monopole antenna, operating in three different frequency bands (2.45 ㎓, 3 ㎓ and 5.2 ㎓), depending upon the state of the lumped element switch. The proposed multiband reconfigurable antenna is designed and fabricated on a 1.6 ㎜ thicker FR-4 substrate having a relative permittivity of 4.4. When the switch is turned ON, the antenna operates in a dual band frequency mode, i.e. WiFi at 2.45 ㎓ (2.06-3.14 ㎓) and WLAN at 5.4 ㎓ (5.11-5.66 ㎓). When the switch is turned OFF, it operates only at 3 ㎓ (2.44-3.66 ㎓). The antenna radiates omni-directionally in these bands with an adequate, bandwidth (>10 %), efficiency (>90 %), gain (>1.2 dB), directivity (>1.7 ㏈i) and VSWR (<2). The fabricated antenna is tested in the laboratory to validate the simulated results. The antenna, due to its reasonably compact size (39 x 37 ㎟), can be used in portable devices such as laptops and iPads.

Seasonal distribution and species composition of daytime biting mosquitoes

Waseem Akram,Faisal HAFEEZ,Unsar Naeem ULLAH,김연국,Aftab HUSSAIN,이종진 한국곤충학회 2009 Entomological Research Vol.39 No.2

Adults and immatures of Aedes mosquito populations were collected at temperatures between 40 and 44°C (summer), while larvae were collected at 0°C (winter). Major mosquito activities were observed from February to mid-December at various collection sites that yielded high populations of Aedes spp. from May to September, and high populations of Culex spp. and Anopheles spp. from March to September. In June to July, mosquito activity was suspended because the relative humidity was high (70%); a result of the monsoon rains. In August, with temperature ranging from 38 to 42°C, the populations of Culex, Anopheles and Aedes began to increase (36.8, 32.1 and 26.3%, respectively). Population estimates (through standard prototype Centers for Disease Control (CDC) and Biogents (BG)-sentinel) and species composition of Aedes in forest habitats indicated a rapid increase in the populations of Ae. albopictus (52.3%), Ae. aegypti (19.1%) and Ae. vittatus (28.5%) following the rainy season in July. Areas positive for Ae. albopictus had identical population levels and distribution ranges of Ae. vittatus, however, there were no Ae. aegypti in Ae. albopictus areas from August to September. The population level, seasonal distribution, habitat and areas of adult activity marked by global positioning system (GPS) coordinates are being used for reference and for species composition data of Anopheles spp. (2), Culex spp. (10) and Aedes spp. (5) in addition to associated temperature, relative humidity and physico-chemical factors of larval habitat. Global meteorological changes have caused an expansion of the active period, leading to the mosquito's possibility of being a vector of disease increasing, resulting in the spread of dengue fever.

Simultaneous Equations and Endogeneity in Corporate Finance: The Linkage between Institutional Ownership and Corporate Financial Performance

MALIK, Qaisar Ali,HUSSAIN, Shahzad,ULLAH, Naeem,WAHEED, Abdul,NAEEM, Muhammad,MANSOOR, Muhammad Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.3

The objective of this research is to explore the inconclusive theoretical and empirical association between institutional ownership and firm performance in the context of emerging Pakistani economy. The data set consists of all the non-financial firms listed on the Pakistan Stock Exchange (PSX). Annual data set covers the period ranging from 2010 to 2015. However, the econometric analysis does not include those firms with incomplete data. Thus the final data set comprised of an unbalanced panel of sample of 276 firms with 1231 firms years observations. Data related to the institutional ownership and other variables taken for the study were extracted through the annual financial reports of the firms. The research used Tobin's Q as a proxy of market measure of firm performance and tested the endogenous relation with institutional ownership through OLS and 2SLS approach. The study also applied Durbin-Wu-Hausman test to determine the endogeneity before analyzing the 2SLS model. The Durbin-Wu-Hausman Test (DWH) conform the endogenous link between institutional ownership and performance and vice versa. The results derived from 2SLS also confirm a highly significant relationship and two way direct proportional relationships between the institutional investment and corporate performance in the studied companies.