Sharma C.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Vishwakarma D.K.,PDPM Indian Institute of Information Technology, Design & Manufacturing
IEEE Antennas and Wireless Propagation Letters | Year: 2017
A new fractal curve along with its iterative function system based on Koch curve is proposed and used for the miniaturization of Fibonacci spiral antenna (FSA). This curve possesses semicircular sections so as to maintain the symmetry with quarter circular sections of FSA. The modified Koch curve owing to its curvatures facilitates a smoother flow of surface current along the spiral arms fractalized with it, unlike uneven current distribution when fractalized with conventional sharp-cornered Koch curve. The second iterate of this curve has resulted in nearly 50% of size reduction by maintaining an equivalent arm length needed for the operation at lowest frequency. The numerical analysis and measurements confirm the retention of inherent broadband characteristics of the FSA and its miniaturized prototypes in the absence of ground plane with excellent radiation properties. © 2002-2011 IEEE.
Gupta R.D.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Parihar M.S.,PDPM Indian Institute of Information Technology, Design & Manufacturing
IEEE Antennas and Wireless Propagation Letters | Year: 2017
A differentially fed rectangular dielectric resonator antenna (DRA) is presented. The DRA is excited by a microstrip gap between two identical transmission lines carrying a differential signal. It is shown that this new method can be adopted to excite the fundamental TE1δ1 mode in a rectangular DRA. Furthermore, by adding a stub to each transmission line, an additional nonradiating resonance is obtained that results in bandwidth enhancement. A conventional hybrid (rat-race) coupler is used for a single-end operation. A common ground plane is shared between the DRA (placed in +z-plane) and the hybrid coupler (placed in -z-plane) to preserve the footprint of the antenna. For S11 ≤ -10 dB, a wide impedance bandwidth of 30% is measured from 2.27 to 3.07 GHz. Additionally, a surface-mounted short horn (SMSH) is incorporated to enhance the boresight gain throughout the band. In measurements, an optimum boresight gain of 12.2 dBi with an improvement of 5.8 dB is obtained at 2.6 GHz using the proposed DRA with SMSH. © 2002-2011 IEEE.
Ansari M.Z.,PDPM Indian Institute of Information Technology, Design & Manufacturing
AIP Conference Proceedings | Year: 2017
This study presents the deflection, resonant frequency and maximum von Mises stress properties of a step profile silicon microcantilever that can be used as the sensing element in a microcantilever biosensor. The adsorbate-induced surface stress change is modelled as in-plane, longitudinal tensile force. A finite element software ANSYS is used for the analysis. Since the sensitivity of microcantilever biosensor depends on both the deflection and fundamental resonant frequency of the cantilever, this work investigates the effect of step length and step thickness variation on the deflection and frequency characteristics of the step cantilever. Results show that step cantilever has better design sensitivity than the rectangular and that by selecting appropriate step size the sensitivity of the step cantilever can be improved significantly. © 2017 Author(s).
Kumar Singh V.,Indian Institute of Technology Kanpur |
Kumar Singh V.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Mazhari B.,Indian Institute of Technology Kanpur
Applied Physics Letters | Year: 2013
Conventional method used for measurement of linearly extrapolated threshold voltage from the slope of I SD vs. VGS characteristics in organic thin film transistors (OTFTs) suffers from the influence of gate dependence of field mobility and its use for comparing different devices can result in anomalous trends. In the present work, an improved method is described, which eliminates the effects of mobility and yields a unique value of threshold voltage. Experimental results obtained with pentacene OTFTs with two different dielectric materials are presented, which show that actual threshold voltage can be very different than the values estimated using the conventional technique. © 2013 AIP Publishing LLC.
Pandey R.K.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Kumar N.,PDPM Indian Institute of Information Technology, Design & Manufacturing
New Astronomy | Year: 2012
The purpose of this paper is to propose an efficient numerical method for solving Lane-Emden type equations arising in astrophysics using Bernstein polynomials. First Bernstein operational matrix of differentiation is derived using Bernstein polynomials and then applied to solve the linear and nonlinear differential equations of Lane-Emden type. Some illustrative examples are given to demonstrate the efficiency and validity of the proposed algorithm. © 2011 Elsevier B.V. All rights reserved.
Kankar P.K.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Sharma S.C.,Indian Institute of Technology Roorkee |
Harsha S.P.,Indian Institute of Technology Roorkee
Neurocomputing | Year: 2013
Fault diagnosis of bearings under localized defects is essential in the design of high performance rotor bearing system. Traditionally, fault diagnosis of rolling element bearings is carried out performed by the use of signal processing methods, which assume statistically stationary signal features. This paper presents a feature-recognition system for rolling element bearings fault diagnosis, which utilizes cyclic autocorrelation of raw vibration signals. Cyclostationary analysis of non-stationary signals clearly indicates the appearance of several distinct modulating frequencies. The coefficients of wavelet transform are calculated using six different base wavelets, after calculating cyclic autocorrelation of vibration signals. The base wavelet that maximizes the Energy to Shannon Entropy ratio is selected to extract statistical features from wavelet coefficients. Finally, a comparative study is carried out with the calculated statistical features as input to soft computing techniques. Three soft computing techniques are used for faults classifications, out of which two are supervised techniques i.e. Support vector machine, Artificial Neural Network and other one is an unsupervised technique i.e. Self-Organizing Maps. The Complex Gaussian wavelet is selected based on maximum Energy to Shannon Entropy ratio. The results show that the support vector machine identifies the fault categories of rolling element bearing more accurately and has a better diagnosis performance. © 2013 Elsevier B.V.
Pal V.K.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Tandon P.,PDPM Indian Institute of Information Technology, Design & Manufacturing
International Journal of Advanced Manufacturing Technology | Year: 2013
Abrasive water jet machining (AWJM) is mainly used to through cut materials that are difficult to cut by conventional machining processes. This process may also be used for controlled depth milling (CDM) of materials. This work focuses on making blind pockets of controlled depths for a set of materials with AWJM. The materials used in the present work are AL 6061 alloy, AL 2024, brass 353, titanium (Ti6Al4V), AISI 304 (SS), and tool steel (M2 Rc 20). The effects of the milling depth and material characteristics on milling time are investigated. It is observed that machinability index and mechanical properties of the materials milled play important role in establishing milling time and surface roughness. It is found that traverse speed of AWJ process is lower for the materials with low machinability index and vice versa. Besides, the milling time increases non-linearly as the depth of milling increases due to loss of energy of jet and increase in standoff distance (SOD). © 2012 Springer-Verlag London Limited.
Rai P.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Khanna P.,PDPM Indian Institute of Information Technology, Design & Manufacturing
2010 5th International Conference on Industrial and Information Systems, ICIIS 2010 | Year: 2010
In this paper a new approach is proposed to recognize gender from the face image. This approach will detect the face from the given image. Radon and Wavelet Transforms are combined to extract key facial features for each face images of male and female. These features will be used to classify the face images of each pattern. We have compared the DCT extracted face feature with our face feature extracted by Radon and Wavelet Transforms. The experimental result shows that the proposed approach (combination of face detector, radon and wavelet transforms, KNN classifier) achieves better performance. ©2010 IEEE.
Mukherjee B.,PDPM Indian Institute of Information Technology, Design & Manufacturing
2nd International Conference on Signal Processing and Integrated Networks, SPIN 2015 | Year: 2015
In this paper, a novel sierpinski carpet fractal based Photonic Band Gap (PBG) structure has been proposed. Whereas the square lattice shaped PBG consisting of drilled holes of radius r1=0.8 cm placed at a periodicity of p=3 cm, offers a band gap from 1.6 GHz to 1.95 GHz for a dielectric material of εr=9.8, the addition of secondary holes of radius r2=0.15 cm placed at a distance of δ=1 cm, from the central hole offers a wider band gap from 1.64 GHz to 2.04 GHz. This same structure is then investigated at THz frequency range by keeping the ratio of periodicity of holes to the operating wavelength, constant. Thus, the band gap now shifts to 16.4 THz to 20.4 THz. The proposed PBG can offer effective solutions to PBG based optical fibers and nano antennas for THz and optical communication applications. © 2015 IEEE.
Kumar A.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Rafi S.M.,PDPM Indian Institute of Information Technology, Design & Manufacturing |
Singh G.K.,Indian Institute of Technology Roorkee
Digital Signal Processing: A Review Journal | Year: 2012
In this work, a hybrid method in frequency domain for design of a linear-phase quadrature mirror filter bank is proposed. The nonlinear least square hybrid method based on Levenberg-Marquardt (LM) and Quasi-Newton (QN) is developed for the design of a low-pass prototype filter whose responses in the passband and stopband are ideal, and the filter bank response at quadrature frequency is 0.707. The proposed method is employed to optimize the quadratic measure of ideal characteristics of the prototype filter and filter bank at quadrature frequency. Performance and effectiveness of the proposed method in terms of peak reconstruction error (PRE), mean squares error in passband and stopband regions, and error in transition band at quadrature frequency are shown through numerical examples and comparison of the results with other existing method. It was found that the proposed method is very simple and easy to implement for QMF bank design problem. © 2012 Elsevier Inc. All rights reserved.