(SoE) School of Engineering

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

Scheduling a meeting is a difficult task for people who have overbooked calendars and many constraints. This activity becomes further complex when the meeting is to be scheduled between parties who are situated in geographically distant locations of a city and have varying traveling patterns. We extend the work of previous authors in this domain by incorporating some real life constraints (varying travel patterns, flexible meeting point and considering road network distance). We also generalize the problem by considering variable number of users. The previous work does not consider these dimensions. The search space for optimal meeting point is reduced by considering convex hull of the set of users locations. It can be further pruned by considering other factors, e.g., direction of movement of users. Experiments are performed on a real-world dataset and show that our method is effective in stated conditions. © 2013 IFIP International Federation for Information Processing.

Computer Science and Engineering

World University root node

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Analyzing travel patterns for scheduling in a dynamic environment

This paper introduces a low complexity adaptive channel estimation technique for OFDM based two-way relay systems. The adaptive filter used is known as Group Fast Array Multichannel 2D-Recursive Least Square (GFAM 2DRLS) filter. It has a computational complexity comparable to that of 2D-Normalized Least Mean Square (2D-NLMS) algorithm while maintaining the same convergence rate as the classic 2D Recursive Least Square (2D-RLS) algorithm. It considers the correlation of the channel frequency response in both time and frequency, while estimating the channel. In order to reduce the number of training data for time varying channel, the channel estimation is carried out based on the Decision Directed (DD) principle. It is assumed that the relay is capable of performing complex signal processing tasks. Hence the channel estimation is performed at the relay. Since the Channel State Information (CSI) is available at the relay, it could perform Multiple Input Multiple Output (MIMO) precoding of the transmitted data. Hence CSI is not required at the transmitting nodes. The convergence rate of GFAM 2D-RLS is compared with the existing 2D-NLMS algorithm and the computational complexity at each iteration is tabulated. Simulations are performed using MATLAB. © 2013 IEEE.

Electrical Engineering

International Conference on Next Generation Mobile Applications, Services, and Technologies

Low complexity 2D adaptive channel estimation for OFDM based two-way relay systems

In this paper we introduce the concept of Adaptive Orthogonal Frequency Division Multiplexing (AOFDM) for two-way relay systems. In order to implement AOFDM at the nodes, the Channel State Information (CSI) is required. Usually CSI is estimated and hence the effect of estimation error should be considered while implementing AOFDM. In the case of two-way relay, channel estimation at the nodes usually result in the overall channel between the source and relay. But for implementing AOFDM, we require the individual channel between node and relay. We propose a simple method to obtain the individual channel assuming that the estimate of combined channel is available. The loading algorithm used is the Levin-Campello loading algorithm. But the general frame work provided by us can be used to implement other loading algorithms for two-way relay systems. © 2013 IEEE.

2013 Annual International Conference on Emerging Research Areas, AICERA 2013 and 2013 International Conference on Microelectronics, Communications and Renewable Energy, ICMiCR 2013 - Proceedings

AOFDM based two-way relay systems

Understanding the erosion mechanism is a key to improve the performance of material subjected to erosive condition. Capability to predict the erosion mechanism could prove to be useful tool. In this work, a parameter named "erosion mechanism identifier," ξ, is proposed to predict the erosion mechanism in materials. Suitability of ξ in predicting erosion mechanism of ductile and brittle materials was evaluated using the data reported in the literature. It was observed that ξ is able to predict the erosion mechanism for both categories of material. The predictability of ξ was not restrained by different operating conditions. © 2013 Springer Science+Business Media New York.

Mechanical Engineering

Tribology Letters

Identifying erosion mechanism: A novel approach

The liquid impingement erosion behavior of a zirconium-based bulk metallic glass (BMG), Zr44Ti11Cu10Ni10Be 25, was evaluated in this study. For comparison, commonly used hydroturbine steel was evaluated under the same test conditions. BMG demonstrated more than four times higher resistance against cavitation erosion compared with hydroturbine steel. The unusually high erosion resistance for BMG is attributed to its uniform amorphous structure with no grain boundaries, higher hardness, and ability to accommodate strain through localized shear bands. Copyright © Materials Research Society 2013.

Journal of Materials Research

Unusually high erosion resistance of zirconium-based bulk metallic glass

Friction stir processing (FSP) has proved to be a viable tool for enhancing the mechanical properties of materials, however, the major focus has been upon improving the bulk properties of light metals and their alloys. Hydroturbines are susceptible to damage owing to slurry and cavitation erosion. In this study, FSP of a commonly employed hydroturbine steel, 13Cr4Ni was undertaken. Microstructural characterization of the processed steel was conducted using optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electron back scatter diffraction (EBSD) techniques. Mechanical characterization of the steel was undertaken in terms of microhardness and resistance to cavitation erosion (CE). FSP resulted in the refinement of the microstructure with reduction in grain size by a factor of 10. EBSD results confirmed the existence of submicron and ultrafine grained microstructure. The microhardness of the steel was found to enhance by 2.6 times after processing. The processed steel also showed 2.4 times higher resistance against cavitation erosion in comparison to unprocessed steel. The primary erosion mechanism for both the steels was identical in nature, with plastic deformation responsible for the loss of material. © 2013 Elsevier B.V.

Applied Surface Science

Surface modification of hydroturbine steel using friction stir processing

Performance of hydropower plant is severely affected by the presence of sand particles in river water. Degree of degradation significantly depends on the level of operating parameters (velocity, impingement angle, concentration, particle size and shape), which is further related to erosion mechanism. In this investigation, the effect of some of these operating parameters on erosion mechanism of generally used hydroturbine steel, CA6NM (13Cr4Ni), is reported. Morphology and variation in the martensite and austenite phases of the eroded surfaces were investigated using SEM and XRD. It was observed that velocity and impingement angle affect the erosion mechanism of CA6NM steel. Erosion mechanism was also significantly affected by the radial distance from the impact zone. Primary mechanism responsible for the removal of material at normal impingement angle was the formation and removal of platelets. At acute impingement angle, ploughing was observed to be one of the prime mechanisms responsible for the loss of the material. Other than these two well-known erosion mechanisms, the presence of another two erosion mechanisms was also observed. Models have been proposed for these unfamiliar erosion mechanisms. Interaction amongst different operating parameters was studied using line and contour plots. It was observed that the interaction between velocity and concentration was most significant. Using the experimental results, a statistical model based on regression approach was developed. Validity of this statistical model was checked using the experimental results from the literature and present study. © 2013 Springer Science+Business Media New York.

Slurry erosion mechanism of hydroturbine steel: Effect of operating parameters

Frequency modulated thermography is becoming a popular thermal non-destructive testing (TNDT) technique which like other active thermographic techniques, requires an external heating stimulus, preferably on a blackened surface. It is however, not immune to non-ideal situation like non-uniform heating and surface emissivity variation. The phase image helps to reduce the effect of surface emissivity variation to some extent, but is inadequate in case of large variations. Further, structural noise can significantly interfere with the process of defect detection, as in the case of carbon fibre composite materials. This paper proposes two image reconstruction algorithms for off-line reduction of structural noise. The first utilizes the periodic nature of structural noise if present, and removes it using 2-dimensional Fourier transformation and a spatial band-stop filter. The other uses time serial reconstruction algorithm to remove such noise. The latter was originally proposed by the authors to remove artifacts from surface emissivity variation on metallic samples. The performances of both algorithms are successfully demonstrated on a carbon fibre test piece, having 2mm, 4mm, and 6mm diameter back drilled holes at various depths ranging from 0.25mm to 2mm in steps of 0.25mm. © 2013 SPIE.

Proceedings of SPIE - The International Society for Optical Engineering

Structural noise reduction in frequency modulated thermal wave imaging of carbon fibre composite materials

In this work, 2,3,5,6-tetrafluoro-7,7′,8,8′- tetracyano quinodimethane (F4-TCNQ) diffusion has been studied using secondary ion mass spectroscopy (SIMS). SIMS depth profiling has been performed in dual beam mode, in which, a low energy oxygen beam has been used for etching and a high energy Bi1+ ion beam has been used for analysis. F4-TCNQ has been identified by the distinguishable presence of fluorine in organic layers. For this study, organic light emitting diodes (OLEDs) were fabricated with F4-TCNQ as a hole injection layer with 1, 2.5 and 5.5 nm thicknesses. The diffusion length and depth were measured to be 13, 19, 19.1 nm and 27, 28, 29 nm for 1, 2.5, 5.5 nm thicknesses of F 4-TCNQ, respectively. The diffusion of F4-TCNQ into the hole transport layer leads to the ionization of F4-TCNQ molecules and p-type doping of the hole transport material. The effect of the electric field on the diffusion was also studied by performing the depth profiling on electric field applied OLEDs and it was observed that the application of the electric field has increased both the diffusion length and depth of F4-TCNQ. This effect was found to be more pronounced for the OLED with 1 nm thickness of F4-TCNQ in comparison to the OLEDs with 2.5 and 5.5 nm thicknesses of F4-TCNQ. The field affected diffusion length and depth were found to be 14.5, 19.5, 19.6 and 35, 28.6, 29.6 nm for OLEDs with 1, 2.5, 5.5 nm thicknesses of F4-TCNQ hole injection layer. The decrease in the field effect has been ascribed as being due to the increase in the cluster density and size. Further, the effect of F4-TCNQ diffusion on OLEDs has been studied by capturing the optical images at different instances of time. OLEDs with 1 nm F4-TCNQ layer were found to be the most unstable. This effect has been ascribed as being due to diffusion of F4-TCNQ into the emissive layer which leads to the dissociation of excitons formed inside the emissive layer. © 2013 The Royal Society of Chemistry.