National Institute of Technology, Meghalaya

About: National Institute of Technology, Meghalaya is a education organization based out in Shillong, India. It is known for research contribution in the topics: Control theory & Computer science. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

Parallel reachability analysis for hybrid systems

Abstract: We propose two parallel state-space-exploration algorithms for hybrid automaton (HA), with the goal of enhancing performance on multi-core shared-memory systems. The first uses the parallel, breadth-first-search algorithm (PBFS) of the SPIN model checker, when traversing the discrete modes of the HA, and enhances it with a parallel exploration of the continuous states within each mode. We show that this simple-minded extension of PBFS does not provide the desired load balancing in many HA benchmarks. The second algorithm is a task-parallel BFS algorithm (TP-BFS), which uses a cheap precomputation of the cost associated with the post operations (both continuous and discrete) in order to improve load balancing. We illustrate the TP-BFS and the cost precomputation of the post operators on a support-function-based algorithm for state-space exploration. The performance comparison of the two algorithms shows that, in general, TP-BFS provides a better utilization/load-balancing of the CPU. Both algorithms are implemented in the model checker XSpeed. Our experiments show a maximum speed-up of more than 2000 x on a navigation benchmark, with respect to SpaceEx LGG scenario. In order to make the comparison fair, we employed an equal number of post operations in both tools. To the best of our knowledge, this paper represents the first attempt to provide parallel, reachability-analysis algorithms for HA.

Numerical investigation of entropy generation in microporous channel with thermal radiation and buoyancy force

Abstract: Microporous channels found to have extensive applications in many fields of engineering, particularly in thermal and petrochemical engineering. In particular, the microelectromechanical systems are useful to develop a large number of microscopic devices and systems such as micromixture, microheat exchangers, microchannel heat sinks, microfuel cells. The present work aims to scrutinize the combined effects of thermal radiation and buoyancy force on entropy generation in magneto-hydrodynamic Jeffrey fluid flow through a vertical microporous channel. The model equations of linear momentum and energy balance are developed and tackled numerically using fourth-order Runge–Kutta method. The results are exhibited pictorially and discussed quantitatively for active parameters which emerged in the mathematical formulation. Validation with previously published work is included, and the current results are in good agreement. It is found that the effects of viscous dissipation and suction/injection on entropy generation in microchannel are important and should not be ignored. Further, it is noticed that the fluid temperature retards with an increasing value of suction and the effect is reversed in the case of injection.

Noncontiguous Channel Allocation for Multimedia Communication in Cognitive Radio Networks

Abstract: In conventional wireless systems, unless a contiguous frequency band with width at least equal to the required bandwidth is obtained, multimedia communication cannot be effected with the desired quality of service. We propose here a novel channel allocation technique to overcome this limitation in a cognitive radio network, which is based on utilizing several noncontiguous channels, each of width smaller than the required bandwidth, but whose sum equals at least the required bandwidth. We present algorithms for channel sensing, channel reservation, and channel deallocation along with transmission and reception protocols with two different implementations based on FDM-FDMA and OFDM-FDMA techniques. Simulation results for both these implementations show that the proposed technique outperforms the existing first-fit and best-fit allocation techniques in terms of the average number of attempts needed for acquiring the necessary number of channels for all traffic situations ranging from light to extremely heavy traffic. Furthermore, the proposed technique can allocate the required numbers of channels in less than 1 s with FDM-FDMA even (4.5 s with OFDM-FDMA ) for 96% traffic load, while the first-fit and best-fit techniques fail to allocate any channel in such situations.

Rainfall-Induced Slope Failures and Use of Bamboo as a Remedial Measure: A Review

Abstract: Problems due to slope instability during rainfall season can cause major landslides occurrences. Different rainfall intensities and duration affect the slope in different manners. To counter this problem, numerous studies have been carried and many innovative techniques have come up on how to stabilize the soil so as to ensure stability. The different techniques involve chemical stabilization, retaining walls, vegetation, different methods of reinforcements, etc. Most of these methods are proving to be fatal to the environment; hence, sustainable methods of reinforcements are the latest area of interests. Bamboo has been widely used as a reinforcement material for soil stabilization. This paper presents the current state of art on the application of bamboos in the stabilization of landslide caused due to rainfall. Bamboo can be used in many forms and has proven to be effective in almost all its forms. Various ways that a bamboo can be used as reinforcements are studied in detail.

Vedic division methodology for high-speed very large scale integration applications

Abstract: Transistor level implementation of division methodology using ancient Vedic mathematics is reported in this Letter. The potentiality of the ‘Dhvajanka (on top of the flag)’ formula was adopted from Vedic mathematics to implement such type of divider for practical very large scale integration applications. The division methodology was implemented through half of the divisor bit instead of the actual divisor, subtraction and little multiplication. Propagation delay and dynamic power consumption of divider circuitry were minimised significantly by stage reduction through Vedic division methodology. The functionality of the division algorithm was checked and performance parameters like propagation delay and dynamic power consumption were calculated through spice spectre with 90 nm complementary metal oxide semiconductor technology. The propagation delay of the resulted (32 ÷ 16) bit divider circuitry was only ∼300 ns and consumed ∼32.5 mW power for a layout area of 17.39 mm2. Combination of Boolean arithmetic along with ancient Vedic mathematics, substantial amount of iterations were reduced resulted as ∼47, ∼38, 34% reduction in delay and ∼34, ∼21, ∼18% reduction in power were investigated compared with the mostly used (e.g. digit-recurrence, Newton–Raphson, Goldschmidt) architectures.