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

We study some well-known graph contraction problems in the recently introduced framework of lossy kernelization. In classical kernelization, given an instance (I, k) of a parameterized problem, we are interested in obtaining (in polynomial time) an equivalent instance (I′, k′) of the same problem whose size is bounded by a function in k. This notion however has a major limitation. Given an approximate solution to the instance (I′, k′), we can say nothing about the original instance (I, k). To handle this issue, among others, the framework of lossy kernelization was introduced. In this framework, for a constant α, given an instance (I, k) we obtain an instance (I′, k′) of the same problem such that, for every c &gt; 1, any c-approximate solution to (I′, k′) can be turned into a (cα)-approximate solution to the original instance (I, k) in polynomial time. Naturally, we are interested in a polynomial time algorithm for this task, and further require that |I′|+k′ = kO(1). Akin to the notion of polynomial time approximation schemes in approximation algorithms, a parameterized problem is said to admit a polynomial size approximate kernelization scheme (PSAKS) if it admits a polynomial size α-approximate kernel for every approximation parameter α &gt; 1. In this work, we design PSAKSs for TREE CONTRACTION, STAR CONTRACTION, OUT-TREE CONTRACTION and CACTUS CONTRACTION problems. These problems do not admit polynomial kernels, and we show that each of them admit a PSAKS with running time kf(α)|I|O(1) that returns an instance of size kg(α) where f(α) and g(α) are constants depending on α. © R. Krithika, Pranabendu Misra, Ashutosh Rai, and Prafullkumar Tale.

Department of Computer Science and Engineering

World University root node

Leibniz International Proceedings in Informatics, LIPIcs

Lossy kernels for graph contraction problems

The internal state of the complex modern processors often needs to be dumped out frequently during postsilicon validation. Since the caches hold most of the state, the volume of data dumped and the transfer time are dominated by the large caches present in the architecture. The limited bandwidth to transfer data present in these large caches off-chip results in stalling the processor for long durations when dumping the cache contents off-chip. To alleviate this, we propose to transfer only those cache lines that were updated since the previous dump. Since maintaining a bit-vector with a separate bit to track the status of individual cache lines is expensive, we propose two methods: 1) where a bit tracks multiple cache lines and 2) an Interval Table which stores only the starting and ending addresses of continuous runs of updated cache lines. Both methods require significantly lesser space compared with a bit-vector, and allow the designer to choose the amount of space to allocate for this design-for-debug feature. The impact of reducing storage space is that some nonupdated cache lines are dumped too. We attempt to minimize such overheads. We propose a scheme to share such cache update tracking hardware (or Update Trackers) across multiple caches in case of physically distributed caches so that they are replicated fewer times, thereby limiting the area overhead. We show that the proposed Update Trackers occupy less than 1% of cache area for both the shared and distributed caches. © 2016 IEEE.

IEEE Transactions on Very Large Scale Integration (VLSI) Systems

Area-Aware Cache Update Trackers for Postsilicon Validation

Barriers have long been recognized as important performance-critical constructs in parallel applications. As a consequence, researchers have proposed fast implementations of barriers in both traditional electrical networks and in non-conventional networks such as optical NoCs. We prove in this paper that current protocols for barriers in optical NoCs are simplistic and cannot be trivially extended to accommodate for normal events that arise in regular operation such as presence of multiple applications, context switches, thread migrations, and variability in the number of active threads. We propose two generic protocols for barriers that can take all such cases into account, are fast, and try to minimize the number of messages sent over the NoC. One of these protocols is a centralized protocol (suitable for less cores), and the other is a distributed protocol, which is scalable. For a suite of standard benchmarks we found the latter to yield a mean speedup of 30.77% over a design that uses a hardware tree barrier. Our barrier implementation per se is roughly 2X and 20X faster than prior implementations that use transmission lines and electrical links respectively. © 2016 IEEE.

Proceedings of the IEEE International Conference on VLSI Design

A Generic Implementation of Barriers Using Optical Interconnects

Complex modulus of an asphalt mixture constitutes two components: E' representing the ability of the mixture to store energy (elastic behavior), and E" reflecting the capacity of the material to dissipate energy (viscous behavior). The main objective of this study was to develop predictive equations for the two components, E' and E", to better quantify and assess the performance of conventional and modified mixtures alternate to standard laboratory testing. The dataset used in this effort encompassed 163 conventional dense graded asphalt concrete (DGAC), 13 asphalt-rubber asphalt concrete (ARAC) gap-graded, and 9 asphalt-rubber friction course (ARFC) open-graded mixes covering 5,550 data points. Aggregate gradation, binder, and volumetric property parameters were used as predictor variables. Squared-error optimization mathematical techniques were employed in developing predictive models. The statistical goodness of fit measures of E' and E" predictive models were very good to excellent. Validation results of the predictive models reflected effectiveness in reproducing observed values with goodness-of-fit measures in the domain of fair to excellent. Sensitivity performance analyses were also carried out to demonstrate the performance of asphalt mixtures with respect to different material properties. © 2016 American Society of Civil Engineers.

Department of Civil Engineering

Journal of Materials in Civil Engineering

Predictive models for storage modulus and loss modulus of asphalt mixtures

Conference on Sustainable Asphalt Pavement for Developing Countries (CONSAP {\ldots}

Investigation on Creep and Recovery Behaviour of Rubber Modified Asphalt Binders

To achieve the goals of energy security and climate change mitigation in Denmark and the EU, an expansion of national production of bioenergy crops is needed. Temporal and spatial variation of yields of willow and Miscanthus is not known for Denmark because of a limited number of field trial data. The semi-mechanistic crop model BioCro was used to simulate the production of both short-rotation coppice (SRC) willow and Miscanthus across Denmark. Predictions were made from high spatial resolution soil data and weather records across this area for 1990–2010. The potential average, rain-fed mean yield was 12.1 Mg DM ha−1 yr−1 for willow and 10.2 Mg DM ha−1 yr−1 for Miscanthus. Coefficient of variation as a measure for yield stability was poorest on the sandy soils of northern and western Jutland, and the year-to-year variation in yield was greatest on these soils. Willow was predicted to outyield Miscanthus on poor, sandy soils, whereas Miscanthus was higher yielding on clay-rich soils. The major driver of yield in both crops was variation in soil moisture, with radiation and precipitation exerting less influence. This is the first time these two major feedstocks for northern Europe have been compared within a single modeling framework and providing an important new tool for decision-making in selection of feedstocks for emerging bioenergy systems. © 2015 The Authors. Global Change Biology Bioenergy Published by John Wiley & Sons Ltd.

Environmental Sciences and Sustainable Engineering Centre (ESSENCE)

Fulltext

GCB Bioenergy

Comparing predicted yield and yield stability of willow and Miscanthus across Denmark

The layered honeycomb magnet α-Li2IrO3 has been theoretically proposed as a candidate to display unconventional magnetic behaviour associated with Kitaev interactions between spin-orbit entangled jeff=1/2 magnetic moments on a honeycomb lattice. Here we report single crystal magnetic resonant x-ray diffraction combined with powder magnetic neutron diffraction to reveal an incommensurate magnetic order in the honeycomb layers with Ir magnetic moments counterrotating on nearest-neighbor sites. This unexpected type of magnetic structure for a honeycomb magnet cannot be explained by a spin Hamiltonian with dominant isotropic (Heisenberg) couplings. The magnetic structure shares many key features with the magnetic order in the structural polytypes β- and γ-Li2IrO3, understood theoretically to be stabilized by dominant Kitaev interactions between Ir moments located on the vertices of three-dimensional hyperhoneycomb and stripyhoneycomb lattices, respectively. Based on this analogy and a theoretical soft-spin analysis of magnetic ground states for candidate spin Hamiltonians, we propose that Kitaev interactions also dominate in α-Li2IrO3, indicative of universal Kitaev physics across all three members of the harmonic honeycomb family of Li2IrO3 polytypes. © 2016 American Physical Society.

Department of Physics

Physical Review B

Incommensurate counterrotating magnetic order stabilized by Kitaev interactions in the layered honeycomb α-Li2IrO3

Inconel 706 superalloy has established itself in the field of gas turbine industry because of its easy fabricability combined with high mechanical strength. Due to its high stress rupture and tensile yield strength, conventional machining of this superalloy exhibits poor surface and low dimensional accuracy of the machined components. It is well known that most of the gas turbine components include complex shaped profile with high precision and hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed to achieve the feasibility in manufacturing of complex shaped components for gas turbine application. In the current investigation, the effect of wire diameter on WEDM performance characteristics such as cutting speed, surface roughness, surface topography, recast layer formation, microhardness, microstructural and metallurgical changes have been evaluated. It was investigated that smaller diameter wire is advantageous over the larger diameter wire since it improves productivity as well as surface quality of the machined components under the same settings of control parameters. In addition, smaller diameter wire has shown comparatively lower recast layer thickness, minimum hardness alteration and shorter manufacturing time. The XRD result has confirmed the presence of residual stress within WED machined component. © 2016 The Society of Manufacturing Engineers

Department of Mechanical Engineering

Journal of Manufacturing Processes

Effect of wire diameter on surface integrity of wire electrical discharge machined Inconel 706 for gas turbine application

Gasketed flange joints are usually subjected to internal pressure at high temperature. The most important requirement of flange joint is to provide leak-free joint under operating condition. In the present study, temperature-dependent nonlinear gasket properties of spiral-wound gasket at elevated temperatures are obtained experimentally and included in the analysis. The relaxation of gasket contact stress in both single and twin-gasketed joints at elevated temperatures is compared. It is observed that the ability to withstand internal pressure decreases with increase in temperature in both single and twin-gasketed flange joints. But, the twin-gasketed flange joint is found to withstand higher internal pressure than single-gasketed joint at a given bolt preload and temperature. The influence of gasket seating surface rotation on the distribution of gasket radial contact stress at elevated temperature is studied. The effect of elevated temperature on flange stresses of twin-gasketed joint is also examined. © Institution of Mechanical Engineers.

Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering

Effect of thermal loading on sealing behavior of single and twin-gasketed flange joints

In this work, the governing equation of asymmetric continuous shaft in inertial frame of reference is studied. In particular, determination of the parameter ranges for the stability or instability of the shaft response is the focus of the present work. The governing equations are a fourth-order coupled partial differential equations containing time dependent coefficients. The equations are non-dimensionalized in terms of two parameters related to the average moment of inertia and the difference of moments of inertia about the principal axes. Using the latter as the asymptotic parameter and employing modal superposition, a formal methodology based on perturbation methods is developed to ascertain the stability and instability characteristics. The methodology is applicable to shafts subjected to some of the classical boundary conditions viz. simply supported, cantilever, and fixed–fixed. Similar stability curves are obtained for each mode for these different boundary conditions. The novel non-dimensionalization scheme chosen leads to the stability boundaries as well as the loci of varying speeds to be in the form of straight lines. The intersection of these lines determine the stable and unstable speed ranges of different asymmetric shafts. The results are generalized for different material and geometric properties of the shaft. © 2016 Elsevier Ltd