Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In orthogonal frequency division multiplexing systems, such as Long Term Evolution (LTE) and WiMAX, the different subcarriers over which a codeword is transmitted may see different signal-to-noise-ratios (SNRs). Thus, adaptive modulation and coding (AMC) in these systems must be based on a vector of subcarrier SNRs seen by the codeword, and is considerably more involved. Exponential effective SNR mapping (EESM) simplifies the problem by mapping the vector of SNRs into a single equivalent flat-fading SNR. However, the analysis of AMC using EESM is challenging owing to its non-linear nature and because it uses an SNR scaling parameter that depends on the modulation and coding scheme. We first propose a novel statistical model for EESM based on the Beta distribution, which is motivated by the central limit approximation for the sum of random variables with finite support. Unlike several ad hoc statistical models, which require three or more parameters to be computed numerically, the proposed model requires only two parameters, for which closed-form expressions are derived for both correlated and uncorrelated subcarrier SNRs. Despite its simplicity, it is as accurate as the ad hoc models. We then present a novel, tight upper bound and an accurate approximation in closed-form for the throughput of a frequency-selective system that uses EESM for AMC. © 2013 IEEE.

Department of Electrical Engineering

World University root node

GLOBECOM - IEEE Global Telecommunications Conference

EESM-based link adaptation in OFDM: Modeling and analysis

Inspired by the Brazilian disk geometry we examine the utility of an edge cracked semicircular disk (ECSD) specimen for rapid assessment of fracture toughness of brittle materials using compressive loading. It is desirable to optimize the geometry towards a constant form factor F for evaluating KI. In this investigation photoelastic and finite element results for KI evaluation highlight the effect of loading modeled using a Hertzian. A Hertzian loading subtending 4° at the center leads to a surprisingly constant form factor of 1.36. This special case is further analyzed by applying uniform pressure over a chord for facilitating testing. © 2013 Elsevier Ltd.

Department of Mechanical Engineering

Engineering Fracture Mechanics

Design and analysis of novel compression fracture specimen with constant form factor: Edge cracked semicircular disk (ECSD)

We report the existence of a Griffiths-like phase over a wide range of x due to the formation of nanosize ferromagnetic clusters in La 0.6Sr0.4Mn1-xCoxO3, the solid solution of ferromagnetic La0.6Sr0.4MnO3 and La0.6Sr0.4CoO3, from the magnetization measurements. In the studied compound, this phase arises due to the quenching of randomly distributed Co-O-Mn antiferromagnetic bonds in the ferromagnetic background. In contrary to the divalent alkaline-earth-doped manganites, the Griffiths-like phase in La0.6Sr0.4Mn1-xCo xO3 can exist entirely in the metallic state above T C (for x &lt; 0.10). Based on the present study, a magnetoelectronic phase diagram is drawn. © 2013 American Chemical Society.

Department of Physics

Journal of Physical Chemistry C

Formation of nanosize griffiths-like clusters in solid solution of ferromagnetic manganite and cobaltite

We present two new primary mechanisms for the synthesis of the rare nucleus Be9, both triggered by ν-induced production of H3 followed by He4(H3,γ)Li7 in the He shells of core-collapse supernovae. For progenitors of ∼8MâŠ™, Li7(H3,n0)Be9 occurs during the rapid expansion of the shocked He shell. Alternatively, for ultra-metal-poor progenitors of ∼11-15MâŠ™, Li7(n,γ)Li8(n,γ)Li9(e-ν̄e)Be9 occurs with neutrons produced by He4(ν̄e,e+n)H3, assuming a hard effective ν̄e spectrum from oscillations (which also leads to heavy element production through rapid neutron capture) and a weak explosion (so the Be9 survives shock passage). We discuss the associated production of Li7 and B11, noting patterns in LiBeB production that might distinguish the new mechanisms from others. © 2013 American Physical Society.

Fulltext

Physical Review Letters

New primary mechanisms for the synthesis of rare be9 in early supernovae

The product dimension of a graph G is defined as the minimum natural number l such that G is an induced subgraph of a direct product of l complete graphs. In this paper we study the product dimension of forests, bounded treewidth graphs and k-degenerate graphs. We show that every forest on n vertices has product dimension at most 1.441 log n + 3. This improves the best known upper bound of 3 log n for the same due to Poljak and Pultr. The technique used in arriving at the above bound is extended and combined with a well-known result on the existence of orthogonal Latin squares to show that every graph on n vertices with treewidth at most t has product dimension at most (t+2)(log n+1). We also show that every k-degenerate graph on n vertices has product dimension at most ⌈5.545k log n⌉+1. This improves the upper bound of 32k log n for the same by Eaton and Rödl.

Department of Computer Science and Engineering

Electronic Journal of Combinatorics

Product dimension of forests and bounded treewidth graphs

Environmental Sciences and Sustainable Engineering Centre (ESSENCE)

98th ESA Annual Convention

Reducing uncertainty through data-driven model development

The electronic structure of the honeycomb lattice iridates Na 2IrO3 and Li2IrO3 has been investigated using resonant inelastic x-ray scattering (RIXS). Crystal-field-split d-d excitations are resolved in the high-resolution RIXS spectra. In particular, the splitting due to noncubic crystal fields, derived from the splitting of jeff=3/2 states, is much smaller than the typical spin-orbit energy scale in iridates, validating the applicability of jeff physics in A2IrO3. We also find excitonic enhancement of the particle-hole excitation gap around 0.4 eV, indicating that the nearest-neighbor Coulomb interaction could be large. These findings suggest that both Na2IrO3 and Li2IrO3 can be described as spin-orbit Mott insulators, similar to the square lattice iridate Sr2IrO4. © 2013 American Physical Society.

Crystal-field splitting and correlation effect on the electronic structure of A2IrO3

The use of natural fibers such as coir for soil improvement is highly attractive in countries where such materials are locally and economically obtainable, in view of the preservation of natural environment and cost effectiveness. This paper discusses shear strength of clay reinforced with randomly distributed coir fibers based on a series of consolidated undrained triaxial compression tests. Test results show that major principal stress at failure for clay-coir fiber matrix increases with increase in fiber content (Wf) and fiber aspect ratio (Ar). For all the combinations of fiber contents and aspect ratios, failure principal stress envelope exhibits a curvilinear variation with a transition at a confining stress, known as critical confining stress. Separate regression analyses have been performed for observations below and above critical confining stress to develop mathematical models, which consider fiber content, aspect ratio, confining stress and plain soil characteristics as the input parameter, to predict major principal stress at failure for the clay-fiber composite. In general, the study identifies that the inclusion of discrete coir fibers in random fashion significantly improves the shear strength of clay and hence could be effectively used for the cases where in-place mixing of soil with fibers is possible (e. g., pavement sub-grade, landfill liner, small embankment). The developed regression models may be used in the design phase for the rough estimation of shear strength of the composite. © 2012 Springer Science+Business Media Dordrecht.

Department of Civil Engineering

Geotechnical and Geological Engineering

Influence of Randomly Distributed Coir Fibers on Shear Strength of Clay

The dynamic analysis of wind turbine drive train is carried out in the present paper. Gear box dynamic modelling is challenging due to the complexity involved in mathematical formulation. The mathematical model is developed based on Lagrange's formulation. The aerodynamic torque which is applied as an external load is calculated from the empirical approach. The input wind fluctuation for simulation is modelled as an average magnitude of the wind which changes slowly in time and a sinusoidal variation of wind velocity is considered. The governing differential equations of motion are solved by an implicit Newmark time algorithm. The Eigen frequencies and Eigen vectors of the model are obtained. The responses of the system in time and frequency domain are also obtained.

20th International Congress on Sound and Vibration 2013, ICSV 2013

Dynamic analysis of drive train of a fixed speed wind turbine

High Cycle Fatigue (HCF) cracks generated by blade vibration are a common source of failure in gas turbine engines. In-situ detection of blade vibration helps operators avoid engine speeds that are critical and helps infer the initiation of cracks via a change in the resonance characteristics of blades. This paper presents the results of dynamic investigations carried out on a Low Pressure Turbine (LPT) rotor through numerical and experimental analyses. In order to meet the mechanical requirements during the development phase, a numerical tool based on finite element analysis (FEA) and an experimental tool based on non-intrusive measurement technique were used. The rotor stage was characterized from resonance perspective by measuring the blade vibration frequencies, amplitudes and the rotational speed of the rotor with small proximity sensors mounted around the turbine casing. The intention was to ensure that the blade design has no critical resonances that interfere with fundamental engine orders in the operating speed range of interest. A Campbell diagram generated using the measured resonances was in good agreement with the predictions. The vibration characteristics ascertained were amplitudes, frequencies, damping and static position of all blades for identifying the initiation of cracks. Detailed analyses were performed to identify the possible causes of failures by observing the anomalies in the blade vibration behaviour and examination of foiled blades.