International Institute of Information Technology, Hyderabad

About: International Institute of Information Technology, Hyderabad is a education organization based out in Hyderabad, India. It is known for research contribution in the topics: Computer science & Authentication. The organization has 2048 authors who have published 3677 publications receiving 45319 citations. The organization is also known as: IIIT Hyderabad & International Institute of Information Technology (IIIT).

Solving the hidden and exposed terminal problems using directional-antenna based MAC protocol for wireless sensor networks

Abstract: A critical design issue for wireless sensor networks (WSNs) is the development of medium access control (MAC) protocols that efficiently reduce power consumption. WSNs sensor nodes are generally powered by batteries which provide a limited amount of energy, and it is often difficult to recharge or replace batteries. Therefore power aware and energy efficient MAC protocols at each layer of the communications are very essential for wireless sensor networks [11]. Fairness to both the usage of a channel and messages may also be traded as for improved power consumptions. In case of classical antennas, unfair channel allocation and wastage of channels between each node can be happened, which is directly affects throughput performance. On the other hand these can bring a problem such as MAC-deadlock, hidden and exposed terminal problem. To overcome these problems a directional antennas have been extensively used in designing MAC protocols for wireless sensor networks. Directional antennas provide many advantages over the classical antennas. These advantages include spatial reuse channel and increases in coverage range distance [9]. One of the main considerations in designing MAC protocols for static wireless sensor networks is to reduce power consumption at the sensor nodes. This is usually done by imposing transmission and receiving schedules on the sensor nodes from only one side at same time. Since it is desirable for a sensor network to be self managed, these schedules need to be worked out by individual nodes in a distributed fashion. In this paper, we show that directional antennas can be used effectively to solve a common hidden and exposed terminal problem by using an energy efficient MAC protocol for wireless sensor networks. This directional Antenna could be rotated in case of base station node to avoid directional hidden terminal problem. Our MAC protocol conserves energy at the nodes by calculating a scheduling strategy at individual nodes and by avoiding packet collisions almost completely.

Stance Classification in Online Debates by Recognizing Users' Intentions

Abstract: Online debate forums provide a rich collection of differing opinions on various topics. In dual-sided debates, users present their opinions or judge other’s opinions to support their stance. In this paper, we examine the use of users’ intentions and debate structure for stance classification of the debate posts. We propose a domain independent approach to capture users’ intent at sentence level using its dependency parse and sentiWordNet and to build the intention structure of the post to identify its stance. To aid the task of classification, we define the health of the debate structure and show that maximizing its value leads to better stance classification accuracies.

Automatic analysis of distance bounding protocols

Abstract: Distance bounding protocols are used by nodes in wireless networks to calculate upper bounds on their distances to other nodes. However, dishonest nodes in the network can turn the calculations both illegitimate and inaccurate when they participate in protocol executions. It is important to analyze protocols for the possibility of such violations. Past efforts to analyze distance bounding protocols have only been manual. However, automated approaches are important since they are quite likely to find flaws that manual approaches cannot, as witnessed in literature for analysis pertaining to key establishment protocols. In this paper, we use the constraint solver tool to automatically analyze distance bounding protocols. We first formulate a new trace property called Secure Distance Bounding (SDB) that protocol executions must satisfy. We then classify the scenarios in which these protocols can operate considering the (dis)honesty of nodes and location of the attacker in the network. Finally, we extend the constraint solver so that it can be used to test protocols for violations of SDB in these scenarios and illustrate our technique on some published protocols.

Evaluation of Site Effects Using HVSR Microtremor Measurements in Vishakhapatnam (India)

Abstract: Dynamic soil properties form an important base for estimation of strains and deformations due to dynamic loading. Frequency, amplitude and time period are the prominent parameters that define a strong ground motion. When the frequency of the soil and strong ground motion reaches to same value during a seismic event, it results in resonance effect leading to huge damage of the structures. Therefore, it is required to estimate the predominant frequency of the soil and amplitude of vibration. Invasive and non-invasive techniques can be employed to determine the dynamic soil properties. Invasive methods, including SPT, DCPT, downhole, cross hole, etc., contain source located either on the surface or in a downhole. The non-invasive methods can be classified as single station and multiple source methods. Microtremor method has been gaining a lot of importance due to its feasibility to perform test in densely populated areas and the speed of processing the information. The instrument works on the principle of recording micro-vibrations in the ground of specific amplitude termed as microtremors. Therefore, evaluation of site effects has been attempted using microtremor testing in Vishakhapatnam (India). The city of Visakhapatnam is one among the prominent and largest functional port cities of India. Site effects due to sand and clay soil layers are characteristic of the whole city area. Seismic hazard studies of the study area are required as per the survey by Disaster Management Authority of India (NDMA 2012). The microtremor horizontal-to-vertical spectral ratio (HVSR) method was therefore applied for measuring the free-field response in the city to assess the peak frequency and amplitude of the soil sediments. Nakamura (A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Railway Technical Research Institute/Tetsudo Gijutsu Kenkyujo, Tokyo, 1989) method has been used to analyses the recorded data as it simplifies the recording process and provides accurate results. It has been evident from the results that clear H/V spectral ratio peaks were observed in the entire central parts of the city, whereas in the eastern and western parts lower site response has been observed due to low impedance contrast of gravel with the rock. The predominant frequency hazard map shows frequency distribution of 0.43–10 Hz throughout the city. Frequency is considerably higher in the central part (> 4 Hz) than in the eastern and western parts (> 1 Hz) in the north eastern and south western locations.

Parsing Clothes in Unrestricted Images

Abstract: Parsing for clothes in images and videos is a critical step towards understanding the human appearance. In this work, we propose a method to segment clothes in settings where there is no restriction on number and type of clothes, pose of the person, viewing angle, occlusion and number of people. This is a challenging task as clothes, even of the same category, have large variations in color and texture. The presence of human joints is the best indicator for cloth types as most of the clothes are consistently worn around the joints. We incorporate the human joint prior by estimating the body joint distributions using the detectors and learning the cloth-joint co-occurrences of different cloth types with respect to body joints. The cloth-joint and cloth-cloth co-occurrences are used as a part of the conditional random field framework to segment the image into different clothing. Our results indicate that we have outperformed the recent attempt [16] on H3D [3], a fairly complex dataset.