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Ahuja A.,BITS Pilani K.K. Birla Goa Campus | Wei W.,Carnegie Mellon University | Carley K.M.,Carnegie Mellon University
IEEE International Conference on Data Mining Workshops, ICDMW | Year: 2017

With the prevalence of social media, such as Twitter, short-length text like microblogs have become an important mode of text on the Internet. In contrast to other forms of media, such as newspaper, the text in these social media posts usually contains fewer words, and is concentrated on a much narrower selection of topics. For these reasons, traditional LDA-based sentiment and topic modeling techniques generally do not work well in case of social media data. Another characteristic feature of this data is the use of special meta tokens, such as hashtags, which contain unique semantic meanings that are not captured by other ordinary words. In the recent years, many topic modeling techniques have been proposed for social media data, but the majority of this work does not take into account the specialty of tokens, such as hashtags, and treats them as ordinary words. In this paper, we propose probabilistic graphical models to address the problem of discovering latent topics and their sentiment from social media data, mainly microblogs like Twitter. We first propose MTM (Microblog Topic Model), a generative model that assumes each social media post generates from a single topic, and models both words and hashtags separately. We then propose MSTM (Microblog Sentiment Topic Model), an extension of MTM, which also embodies the sentiment associated with the topics. We evaluated our models using Twitter dataset, and experimental results show that our models outperform the existing techniques. © 2016 IEEE.


Mallya N.B.,BITS Pilani K.K. Birla Goa Campus | Patil G.,BITS Pilani K.K. Birla Goa Campus | Raveendran B.,BITS Pilani K.K. Birla Goa Campus
Proceedings of the IEEE International Conference on VLSI Design | Year: 2015

This paper proposes a novel cache architecture - Way Halted Prediction - to reduce energy consumption and effective access time of set associative caches. This is achieved with the help of halt tag array and prediction circuit. Experimental evaluation of various SPEC benchmark programs on CACTI 5.3 and CASIM simulators reveal that the proposed architecture offers 33%, 6% and 3% savings in dynamic energy consumption and 1.80%, 6.13% and -1.95% saving in effective access time over conventional, way predicting and way halting cache architectures respectively. © 2015 IEEE.


Postnikov E.B.,Kursk State University | Singh V.K.,BITS Pilani K.K. Birla Goa Campus
Multidimensional Systems and Signal Processing | Year: 2014

We propose method for the local spectral analysis of images via the two-dimensional continuous wavelet transform with the Morlet wavelet based on its representation as a solution of the partial differential equation. It has been shown that a transformed function uniquely determines an initial value for the equation, i.e. a Cauchy problem is stated. Its solving implies that scale parameter a plays a role of "time variable" and two translation parameters bx, by are spatial independent variables. Numerical examples are given to illustrate the efficiency of the proposed method. © 2012 Springer Science+Business Media, LLC.


Roul R.K.,BITS Pilani K.K. Birla Goa Campus | Bansal I.,BITS Pilani K.K. Birla Goa Campus
9th International Conference on Industrial and Information Systems, ICIIS 2014 | Year: 2015

Since its inception, mining frequent patterns have become an imperative issue in data mining. The main problem in this area is to find out the association rule that identifies the relationships among a set of items. But the most expensive step in association rule is finding frequent itemsets and hence it draw the attention of many important research. In this paper, we propose a novel tree structure, called GM(Generate and Merge)Tree, which is a combination of prefix based incremental mining using canonical ordering and batch incrementing techniques. Our approach makes the tree structure more compact, canonically ordered of nodes and avoids sequential incrementing of transactions. It also helps to give a scalable algorithm with minimum overheads of modifying the tree structure during update operations. This algorithm is especially expected to give better results in case of extremely large transaction database in a dynamic environment. The experimental work has been carried out on two large datasets. Test results show the efficiency and effectiveness of the proposed approach by outperforming the traditional FP-Tree, CanTree(Canonical-order Tree) and BIT(Batch Incremental Tree). © 2014 IEEE.


Ghonasgi K.,BITS Pilani K.K. Birla Goa Campus | Bakal K.,BITS Pilani K.K. Birla Goa Campus | Mali K.D.,BITS Pilani K.K. Birla Goa Campus
Procedia Engineering | Year: 2016

This work involves study of the first three natural frequencies of the perforated plates. The effect of the parameters which influence them have been studied. The parameters considered are the shape of perforations, pattern of the perforations, aspect ratio of the plate, dimensions of the plate, ligament efficiency and the mass remnant ratio (MRR). The study is focused on the effect of the most influencing parameter on the free vibrations.


Ramesha C.K.,BITS Pilani K.K. Birla Goa Campus | Rajagopal Reddy V.,Sri Venkateswara University
Superlattices and Microstructures | Year: 2014

We have investigated the electrical and structural properties of Pd/4H-SiC Schottky diodes as a function of annealing temperature using I-V, C-V, AES and XRD measurements. The barrier height (BH) of the as-deposited Pd/4H-SiC Schottky diode is found to be 0.71 eV (I-V) and 1.18 eV (C-V), respectively. When the Pd/4H-SiC Schottky diode is annealed at 300 °C, a maximum BH is achieved and corresponding values are 0.89 eV (I-V) and 1.30 eV (C-V). Further, an increase in annealing temperature up to 400 °C, the BH decreases to 0.81 eV (I-V) and 1.20 eV (C-V). Using Cheung's functions, the barrier height (φb), ideality factor (n), and series resistance (Rs) are also calculated. Experimental results clearly indicate that the optimum annealing temperature for the Pd Schottky contact to 4H-SiC is 300 °C. According to the Auger electron spectroscopy (AES) and X-ray diffraction (XRD) results, the formation of interfacial phases at the Pd/4H-SiC interface could be the reason for the increase or decrease in BH upon annealing at elevated temperatures. The overall surface morphology of the Pd/4H-SiC Schottky diode is fairly smooth upon annealing temperatures. © 2014 Elsevier Ltd. All rights reserved.


Goel K.,BITS Pilani KK Birla Goa Campus | Vohra R.,BITS Pilani KK Birla Goa Campus | Kamath A.,BITS Pilani KK Birla Goa Campus | Baths V.,BITS Pilani KK Birla Goa Campus
Conference Proceedings - IEEE International Conference on Systems, Man and Cybernetics | Year: 2014

In this paper, we present a novel brain computer interface based home automation system using two responses - Steady State Visually Evoked Potential (SSVEP) and the eyeblink artifact, augmented by a Bluetooth based indoor localization system, to greatly increase the number of controllable devices. The hardware implementation of this system to control a table lamp and table fan using brain signals has also been discussed and state-of-the-art results have been achieved. © 2014 IEEE.


Sharma C.,BITS Pilani K.K Birla Goa Campus | Banerjee K.,BITS Pilani K.K Birla Goa Campus
Physica A: Statistical Mechanics and its Applications | Year: 2015

We study the various sectors of the Bombay Stock Exchange (BSE) for a period of 8 years from April 2006 to March 2014. Using the data of daily returns of a period of eight years we make a direct model free analysis of the pattern of the sectorial indices movement and the correlations among them. Our analysis shows significant auto correlation among the individual sectors and also strong cross-correlation among sectors. We also find that auto correlations in some of the sectors persist in time. This is a very significant result and has not been reported so far in Indian context. These findings will be very useful in model building for prediction of price movement of equities, derivatives and portfolio management. We show that the Random Walk Hypothesis is not applicable in modeling the Indian market and mean-variance-skewness-kurtosis based portfolio optimization might be required. We also find that almost all sectors are highly correlated during large fluctuation periods and have only moderate correlation during normal periods. © 2015 Elsevier B.V.


Roy A.,Infosys | Sarkar S.,BITS Pilani K.K. Birla Goa Campus | Ganesan R.,Edgeverve Systems Ltd | Goel G.,Jigsaw Academy
ACM Computing Surveys | Year: 2015

In response to the revival of virtualized technology by Rosenblum and Garfinkel [2005], NIST defined cloud computing, a new paradigm in service computing infrastructures. In cloud environments, the basic security mechanism is ingrained in virtualizationthat is, the execution of instructions at different privilege levels. Despite its obvious benefits, the caveat is that a crashed virtual machine (VM) is much harder to recover than a crashed workstation. When crashed, a VM is nothing but a giant corrupt binary file and quite unrecoverable by standard disk-based forensics. Therefore, VM crashes should be avoided at all costs. Security is one of the major contributors to such VM crashes. This includes compromising the hypervisor, cloud storage, images of VMs used infrequently, and remote cloud client used by the customer as well as threat from malicious insiders. Although using secure infrastructures such as private clouds alleviate several of these security problems, most cloud users end up using cheaper options such as third-party infrastructures (i.e., private clouds), thus a thorough discussion of all known security issues is pertinent. Hence, in this article, we discuss ongoing research in cloud security in order of the attack scenarios exploited most often in the cloud environment. We explore attack scenarios that call for securing the hypervisor, exploiting co-residency of VMs, VM image management, mitigating insider threats, securing storage in clouds, abusing lightweight software-as-a-service clients, and protecting data propagation in clouds. Wearing a practitioner's glasses, we explore the relevance of each attack scenario to a service company like Infosys. At the same time, we draw parallels between cloud security research and implementation of security solutions in the form of enterprise security suites for the cloud. We discuss the state of practice in the form of enterprise security suites that include cryptographic solutions, access control policies in the cloud, new techniques for attack detection, and security quality assurance in clouds. © 2015 ACM.


Sharma S.,BITS Pilani K.K. Birla Goa Campus | Clement S.,BITS Pilani K.K. Birla Goa Campus
American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM | Year: 2014

Ground effect is a phenomenon caused by the presence of a fixed boundary layer below a wing. This results in an effective increase in lift to drag ratio of the airfoil. The available literature on this phenomenon is very limited; also the types of airfoils used in traditional aircrafts are not suited for ground effect vehicles, so a computational study has been done comparing traditional airfoils (NACA series) with ground effect airfoil (DHMTU). In this paper, the aerodynamic characteristics of a NACA 6409, NACA 0012, DHMTU 12-35.3-10.2-80.12.2[1] section in ground effect were numerically studied and compared. In 2D simulation, the flow around each of the airfoils has been investigated for different turbulence models viz. Spalart Allmaras turbulence model and k-ε Realizable turbulence models. Lift coefficient, drag coefficient, pitching moment coefficient and lift to drag ratio of each airfoil was determined on several angles of attack from 0 to 10° (0°, 2°, 4°, 6°, 8°, 10°) and different ground clearances (h/c=0.2, 0.4, 0.6, 0.8, 1.0). The results of the CFD simulation indicate a reduction in drag coefficient and an increase in lift coefficient, thus an overall increment in lift to drag ratio of the airfoils, when flying in proximity to the ground. Also DHMTU airfoils have shown a greater consistency in Cm behavior with decreasing height-to- chord (h/c) ratio. Copyright © 2014 by ASME.

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