Federal Urdu University of Arts, Sciences and Technology Islamabad

www.fuuastisb.edu.pk
Islamabad, Pakistan
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Iqbal S.,International iversity | Gualini M.M.S.,Polytechnico di Turin | Rehman A.u.,Federal Urdu University of Arts, Sciences and Technology Islamabad
Optics and Laser Technology | Year: 2010

Laser welding of zinc-coated steel sheets in lap configuration poses a challenging problem, because of the zinc vapours spoiling the quality of the weld. In continuation to the earlier work, the novel solution of dual laser beam method for lap welding of galvanized steel sheets is discussed here in view of the recently obtained observations and ensuing concerns. In this method the precursor beam cuts a slot, thus making an exit path for the zinc vapours, while the second beam performs the needed welding. The metallurgical analysis of the welds is encouraging showing absence of zinc in the welded area. In the current work on this technique, new experimental results have been obtained verifying the earlier observations. Along with this, the possibility of using a transversely split-up beam for the welding purposes with this approach is discussed and analyzed in this paper. This new technique is expected to be very useful in prospective industrial applications requiring higher welding throughput along with the needed quality. © 2009 Elsevier Ltd. All rights reserved.


Gul I.H.,National University of Sciences and Technology | Maqsood A.,National University of Sciences and Technology | Naeem M.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Ashiq M.N.,Bahauddin Zakariya University
Journal of Alloys and Compounds | Year: 2010

Aluminum substituted cobalt ferrite nanoparticles CoFe2-xAl xO4 (for x = 0.00, 0.25, 0.50) have been synthesized by the chemical co-precipitation route. The average crystallite size was calculated using the Scherrer formula and found within 17-27 nm range. The optical absorption spectra of all the samples showed two clear electronic transitions, first is around 0.75 eV while the second at about 0.84 eV. The later is identified by means of 4A2 → 4T 1 (4F) transition while the former is attributed to the overlapping of the 4A2 → 4T1 (4F) transition of the tetrahedral Co2+ ions and the Co2+ + Fe3+ → Co3+ + Fe2+ metal-metal charge transfer transition. The saturation magnetization at room temperatures was found to be 61.50 emu/g for pure CoFe2O4 nanoparticles, while it decreased with increasing Al3+ concentration up to 52.00 emu/g (for x = 0.50). The Curie temperature was determined from AC magnetic susceptibility measurement. It was observed that Curie temperature decreased with Al3+ concentration (x) and DC electrical resistivity decreased with increase in temperature. Activation energy and drift mobility have been calculated from the temperature dependent DC electrical resistivity measurements for all the samples. The variation of dielectric constant, dielectric loss and tangent loss factor for all the samples have been studied as a function of frequency in the range 600 Hz to 1 MHz at room temperature. © 2010 Elsevier B.V. All rights reserved.


Ali H.,University of Agriculture, Peshawar | Qaiser M.,Federal Urdu University of Arts, Sciences and Technology Islamabad
ORYX | Year: 2011

Silene longisepala Nasir (Caryophyllaceae) is a plant endemic to Chitral District in mountainous north-west Pakistan. This taxon was previously known from only two localities. In field studies during 2005-2007, 24 new localities in lower Chitral were discovered. We found 608 mature individual plants in 22 localities in 2005, 520 mature individuals in 17 localities in 2006, and 531 mature individuals in 18 localities in 2007. Considering the population size in 2007, an extent of occurrence of 3,587 km 2 and area of occupancy of 104 km 2, we recommend that the species is categorized as Endangered on the IUCN Red List. The main threat to the species is habitat destruction from road construction, land conversion for agriculture and soil erosion following deforestation; we witnessed the direct effects of these pressures on S. longisepala during our fieldwork. In some localities, however, S. longisepala is fortuitously protected by the general inaccessibility of its habitat. There is no legal framework in Pakistan for the protection of rare and endemic plant taxa on private lands and therefore ex situ conservation may be required for narrow endemics such as S. longisepala. Our methodology in this study, in which we combined detailed field surveys with monitoring, could form a model for conservation research on rare and endemic plant taxa in Pakistan and elsewhere. © 2011 Fauna & Flora International.


Khan M.A.,University of Central Florida | Khan M.A.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Leuenberger M.N.,University of Central Florida
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We propose a two-dimensional Hong-Ou-Mandel (HOM) type interference experiment for massless Dirac fermions in graphene and 3D topological insulators. Since massless Dirac fermions exhibit linear dispersion, similar to photons in vacuum, they can be used to obtain the HOM interference intensity pattern as a function of the delay time between two massless Dirac fermions. We show that while the Coulomb interaction leads to a significant change in the angle dependence of the tunneling of two identical massless Dirac fermions incident from opposite sides of a potential barrier, it does not affect the HOM interference pattern. We apply our formalism to develop a massless Dirac fermion beam splitter (BS) for controlling the transmission and reflection coefficients. We calculate the resulting time-resolved correlation function for two identical massless Dirac fermions scattering off the BS. © 2014 American Physical Society.


Erementchouk M.,University of Central Florida | Khan M.A.,University of Central Florida | Khan M.A.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Leuenberger M.N.,University of Central Florida
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

The nonzero thickness of single-layer (SL) MoS2 manifests in electron states forming classes of states that are even and odd with respect to reflections through the central plane. These states are energetically well separated: In particular, we show that pristine SL MoS2 exhibits two band gaps, Eg∥=1.9 eV and Eg⊥=3.2 eV, for the optical in-plane and out-of-plane susceptibilities χ∥ and χ⊥, respectively. Because of this, odd states are often neglected, which effectively reduces SL MoS2 to a perfect two-dimensional system. We study states bound to defects in SL MoS2 with three types of vacancy defects (VDs), (i) Mo vacancy, (ii) S2 vacancy, and (iii) 3×MoS2 quantum antidot, and show that odd states play an equally important role as the even states. In particular, we show that odd states bound to VDs lead to resonances in χ⊥ inside Eg⊥ in SL MoS2 with VDs. Additionally, we demonstrate that the states bound to VDs are not necessarily confined to the band gap in the even subsystem, which necessitates extending the energy region affected by the bound states. © 2015 American Physical Society.


Khan N.A.,Qatar University | Khan N.A.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Boashash B.,Qatar University | Boashash B.,University of Queensland
IEEE Signal Processing Letters | Year: 2013

This letter presents a novel algorithm to compute the instantaneous frequency (IF) of a multicomponent nonstationary signal using a combination of fractional spectrograms (FS). A high resolution time frequency distribution (TFD) is defined by combining FS computed using windows of varying lengths and chirp rates. The IF of individual signal components is then computed by applying a peak detection and component extraction procedure. The mean square error (MSE) of IF estimates computed with the AFS is lower than the MSE of IF estimates obtained from other TFDs for SNR varying from-5 dB to 16 dB. © 1994-2012 IEEE.


Khan N.A.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Sandsten M.,Lund University
Signal Processing | Year: 2016

This paper proposes a time-frequency (t-f) image enhancement method for suppressing interference terms in the Wigner-Ville distribution. The proposed technique adapts the direction of the smoothing kernel locally at each t-f point, so that the smoothing kernel remains aligned with the ridges of the auto-terms. This local alignment of the smoothing kernel reduces cross-terms without degrading the energy concentration of auto-terms. The results indicate that the proposed time-frequency distribution outperforms other methods in terms of its ability to resolve close signal components. © 2016 Elsevier B.V. All rights reserved.


Baig F.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Beg S.,Federal Urdu University of Arts, Sciences and Technology Islamabad | Khan M.F.,Federal Urdu University of Arts, Sciences and Technology Islamabad
International Journal of Smart Home | Year: 2013

Home automation is a wide and varied field that involves devices as small as temperature, light and motion sensor, and as powerful as modern home appliances. In today's world technology is available for home automation but these technologies are incompatible with each other and addresses only communication and physical media, the main objective of this work is to facilitate the user to control appliances by two ways one is remotely via voice command, second is using remote control to control the appliances which is also an override control.


Imran M.,Federal Urdu University of Arts, Sciences and Technology Islamabad
Journal of Internet Banking and Commerce | Year: 2015

Since last few years social network sites (SNSs) have rapidly grown in popularity and user acceptance globally. They have become the main place for social interaction, discussion and communication. Today, many businesses advertise their products on SNSs. The current study aims to assess the effects of SNSs consumers/users’ beliefs and concerns of social network advertising (SNA) on their attitudes toward SNA and SNS banner ad-clicking behavior. Data was collected from a sample of 397 university students of Pakistan. Results show the beliefs of SNA as informative and entertaining have positive effects on user attitudes toward SNA and their ad-clicking behavior. Similarly, user concern of SNA as irritating has negative effects on both their attitudes toward SNA and ad-clicking behavior. Good for economy is an important socioeconomic belief which affects user attitudes toward SNA positively. The overall results indicate that utilitarian and hedonic aspects of SNA make SNS banner ads effective. © 2015 Imran M.


Ali H.,University of Peshawar | Qaiser M.,Federal Urdu University of Arts, Sciences and Technology Islamabad
Pakistan Journal of Botany | Year: 2010

Astragalus gahiratensis Ali (Fabaceae-Papilionoideae) is endemic to District Chitral Pakistan. The population size i.e. 127 mature individuals were found in 4 localities in 2005, 28 mature individuals were found in 03 localities in 2006 and 107 mature individuals were found in 4 localities in 2007, the taxon deserved the status of Critically Endangered (CR) category. The main threat posed to the taxon is its habitat degradation. Soil erosion resulted from deforestation and grazing are among the other main threats responsible for the reduction in population size. In 3 localities i.e., Chitral-Chaghbeni towards Ishpeder, Chitral-Gokhshal and Chitral Gol-Ishpeder, 75%, 13.79% and 18.64% decrease has been observed in its population size, respectively. There is urgent need to develop species specific conservation strategies, followed by comprehensive conservation action plan and thereafter their implementation at ground root level on national scale.

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