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Gurdaspur, India

Pal Singh R.P.,Desh Bhagat University | Hudiara I.S.,Chitkara University | Bhushan Rana S.,GNDU Regional Campus
Materials Science- Poland | Year: 2016

In the present study, pure ZnO and Fe-doped ZnO (Zn0.97Fe0.03O) nanoparticles were synthesized by simple coprecipitation method with zinc acetate, ferric nitrate and sodium hydroxide precursors. Pure ZnO and Fe-doped ZnO were further calcined at 450 °C, 600 °C and 750 °C for 2 h. The structural, morphological and optical properties of the samples were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and UV-Vis absorption spectroscopy. The X-ray diffraction studies revealed that the as-synthesized pure and doped ZnO nanoparticles have hexagonal wurtzite structure. The average crystallite size was calculated using Debye-Scherrer's formula. The particle size was found to be in nano range and increased with an increase in calcination temperature. SEM micrographs confirmed the formation of spherical nanoparticles. Elemental compositions of various elements in pure and doped ZnO nanoparticles were determined by EDX spectroscopy. UV-Vis absorption spectra showed red shift (decrease in band gap) with increasing calcination temperature. Effect of calcination on the magnetic properties of Fe-doped ZnO sample was also studied using vibrating sample magnetometer (VSM). M-H curves at room temperature revealed that coercivity and remanent polarization increase with an increase in calcination temperature from 450 °C to 750 °C, whereas reverse effect was observed for magnetization saturation. © Wroclaw University of Technology 2016. Source

Pal Singh R.P.,Desh Bhagat University | Hudiara I.S.,Chitkara University | Panday S.,Desh Bhagat University | Rana S.B.,GNDU Regional Campus
Journal of Superconductivity and Novel Magnetism | Year: 2015

In the present work, pure ZnO, Zn 0.99Fe 0.01O (ZFO), Zn 0.99Ni 0.01O (ZNO) and Zn 0.98Fe 0.01Ni 0.01O (ZFNO) dilute magnetic semiconductors were successfully synthesized by using the wet coprecipitation method. Pure and doped samples were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-Vis spectroscopy and vibrating sample magnetometer. The X-ray diffraction (XRD) analysis of pure and doped samples confirms the formation of a hexagonal wurtzite structure, without formation of any other secondary and impurity phases. Surface morphology of pure and doped ZnO nanoparticle samples performed by scanning electron microscopy (SEM) reveals the formation of spherical nanocrystallites with clear and welldefined boundaries. Energy-dispersive X-ray spectroscopy (EDS) indicates the successful substitution of dopant Fe 2+ and Ni 2+ in the lattice site of Zn 2+ and results in the formation of single-phase Zn 1−x−yFe xNi yO. The UV-visible absorption spectra of all doped samples showed blueshift in absorption edge as compared to undoped ZnO nanoparticles. The magnetic characterization reveals and confirms the roomtemperature ferromagnetism in all doped and codoped samples. Magnetization saturation is enhanced in Ni–Fe codoped sample as compare with individual Fe and Nidoped ZnO samples which further reveals that exchange interaction between Fe and Ni ions dominates over the Fe–Fe and Ni–Ni ion interaction. © 2015, Springer Science+Business Media New York. Source

Sood S.K.,GNDU Regional Campus
Information Security Journal | Year: 2011

The password is the most common technique used to authenticate Web users. Password-based authentication protocols are susceptible to automated dictionary attacks because most passwords are chosen by users from their personal domain. In this paper, we propose a cookie-based virtual password authentication protocol that preserves the advantages of conventional password authentication while simultaneously increasing the efforts required for online dictionary attacks. The Web server stores the cookie on the user's machine if the legitimate user authenticates to the Web server. Thereafter, the legitimate user can easily authenticate to the Web server from a machine that contains the cookie. However, the legitimate user requires some additional computational efforts during login from a machine that does not contain the cookie. The computation efforts required from the attacker during login to the Web server increases exponentially with each login failure. The user generated virtual password is different for the same user in different sessions of Secure Socket Layer (SSL) protocol. The concept used in this paper is to combine traditional password authentication with a challenge that is easy to answer by the legitimate user but computational cost increases for the attacker with each login failure. Therefore, even the automated programs cannot launch online dictionary attacks on the proposed protocol. This protocol provides good security against different types of attacks launched by the attacker. The proposed protocol is easy to implement and removes some of the drawbacks of earlier proposed password-based authentication protocols. © Taylor & Francis Group, LLC. Source

Sood S.K.,GNDU Regional Campus
International Journal of Network Security | Year: 2012

Password is the most commonly used authentication technique in smart card based authentication protocols. During communication, the static identity based authentication protocols leaks out the user's authentication messages corresponding to static identity to the attacker. Therefore, the attacker can trace and identify the different requests belonging to the same user. On the other hand, the dynamic identity based authentication protocols provide multifactor authentication based on the identity, password, smart card and hence more suitable to e-commerce applications. In 2008, Liu et al. proposed a nonce based mutual authentication scheme using smart cards. In 2009, Sun et al. demonstrated man-in-the-middle attack on Liu et al.'s scheme. However, we found that Liu et al.'s scheme is also vulnerable to stolen smart card attack. This paper presents a new dynamic identity based authentication scheme that uses the nonce and timestamp at the same time to resolve the aforementioned problems, while keeping the merits of Liu et al.'s scheme. The aim of this paper is to provide a dynamic identity based secure and computational effcient authentication protocol with user's anonymity using smart cards. It protects the user's identity in insecure communication channel and hence can be applied directly to e-economic applications. Security analysis proved that the proposed protocol is secure and practical. Source

Malhotra J.,GNDU Regional Campus
Tamkang Journal of Science and Engineering | Year: 2011

In this paper, performance analysis of Optimum and Sub-optimum diversity combining receivers over generalized fading channels modeled by the three parameter Generic-Gamma model is presented. The Generic-Gamma model is versatile enough to represent short term fading such as Weibull, Nakagami-m or Rayleigh as well as shadowing. The performance measures such as amount of fading, average bit error rate, and signal outage are considered for analysis. With the aid of Moment Generating Function (MGF) approach and Padé approximation (PA) technique outage probability and Average bit error rate have been evaluated for a variety of modulation formats. PA technique has been used to derive simple-to-evaluate compact rational expressions for the MGF of output SNR. Using these novel rational expressions, the performance of multichannel receivers employing diversity combining under a range of representative channel fading conditions have been evaluated. The results have been validated through simulations which shows perfect match. Source

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