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Search Results: 1 - 10 of 2048 matches for " Kaushik Mitra "
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Stability Analysis Of Delayed System Using Bodes Integral
Anish Acharya,Debatri Mitra,Kaushik Halder
Computer Science , 2012,
Abstract: The PID controller parameters can be adjusted in such a manner that it gives the desired frequency response and the results are found using the Bodes integral formula in order to adjust the slope of the nyquist curve in a desired manner. The same idea is applied for plants with time delay . The same has also been done in a new approach . The delay term is approximated as a transfer function using Pade approximation and then the Bode integral is used to determine the controller parameters. Both the methodologies are demonstrated with MATLAB simulation of representative plants and accompanying PID controllers. A proper comparison of the two methodologies is also done. The PID controller parameters are also tuned using a real coded Genetic Algorithm (GA) and a proper comparison is done between the three methods.
A Framework for the Analysis of Computational Imaging Systems with Practical Applications
Kaushik Mitra,Oliver Cossairt,Ashok Veeraraghavan
Computer Science , 2013,
Abstract: Over the last decade, a number of Computational Imaging (CI) systems have been proposed for tasks such as motion deblurring, defocus deblurring and multispectral imaging. These techniques increase the amount of light reaching the sensor via multiplexing and then undo the deleterious effects of multiplexing by appropriate reconstruction algorithms. Given the widespread appeal and the considerable enthusiasm generated by these techniques, a detailed performance analysis of the benefits conferred by this approach is important. Unfortunately, a detailed analysis of CI has proven to be a challenging problem because performance depends equally on three components: (1) the optical multiplexing, (2) the noise characteristics of the sensor, and (3) the reconstruction algorithm. A few recent papers have performed analysis taking multiplexing and noise characteristics into account. However, analysis of CI systems under state-of-the-art reconstruction algorithms, most of which exploit signal prior models, has proven to be unwieldy. In this paper, we present a comprehensive analysis framework incorporating all three components. In order to perform this analysis, we model the signal priors using a Gaussian Mixture Model (GMM). A GMM prior confers two unique characteristics. Firstly, GMM satisfies the universal approximation property which says that any prior density function can be approximated to any fidelity using a GMM with appropriate number of mixtures. Secondly, a GMM prior lends itself to analytical tractability allowing us to derive simple expressions for the `minimum mean square error' (MMSE), which we use as a metric to characterize the performance of CI systems. We use our framework to analyze several previously proposed CI techniques, giving conclusive answer to the question: `How much performance gain is due to use of a signal prior and how much is due to multiplexing?
Rectangular Microstrip Antenna with Air Cavity for High Gain and Improved Front to Back Ratio  [PDF]
Kaushik Malakar, Jaydeep Nandi, Souvik Mitra, Prasanta Kumar Gorai, Sudipta Chattopadhyay, Sandip Banerjee
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2011, DOI: 10.4236/jemaa.2011.39058
Abstract: A rectangular microstrip patch antenna using conventional Poly Tetra Fluride Ethelene (PTFE) substrate with air cavity is proposed and theoretically investigated. Considerably high gain along with improved front to back radiation isolation is demonstrated using such proposed antenna. The radiation performance of this new antenna has been compared to a conventional microstrip patch for some commonly used aspect ratios (width to length ratio). Compared to conventional microstrip antenna the proposed configuration shows more than 12% increment in peak gain and more than 10% increment in front to back radiation performance in each set of aspect ratio. The elucidation of such improvement in the radiation characteristics of the proposed antenna is also presented.
An energy efficient scheme for data gathering in wireless sensor networks using particle swarm optimization
Ayon Chakraborty,Kaushik Chakraborty,Swarup Kumar Mitra,Mrinal K. Naskar
Journal of Applied Computer Science & Mathematics , 2009,
Abstract: Energy efficiency of sensor nodes is a sizzling issue,given the severe resource constraints of sensor nodes andpervasive nature of sensor networks. The base station beinglocated at variable distances from the nodes in the sensor field,each node actually dissipates a different amount of energy totransmit data to the same. The LEACH [4] and PEGASIS [5]protocols provide elegant solutions to this problem, but may notalways result in optimal performance. In this paper we haveproposed a novel data gathering protocol for enhancing thenetwork lifetime by optimizing energy dissipation in the nodes.To achieve our design objective we have applied particle swarmoptimization (PSO) with Simulated Annealing (SA) to form asub-optimal data gathering chain and devised a method forselecting an efficient leader for communicating to the basestation. In our scheme each node only communicates with aclose neighbor and takes turns in being the leader depending onits residual energy and location. This helps to rule out theunequal energy dissipation by the individual nodes of thenetwork and results in superior performance as compared toLEACH and PEGASIS. Extensive computer simulations havebeen carried out which shows that significant improvement isover these schemes.
Superior Vena Cava Thrombosis in a Case of Lung Adenocarcinoma
Santanu Ghosh,Kaushik Saha,Arnab Saha,Mrinmoy Mitra
Middle East Journal of Cancer , 2013,
Abstract: Superior vena cava syndrome is a common presentation of bronchogenic carcinoma. The mechanism of obstruction is by compression of superior vena cava by the bronchogenic tumor itself or enlarged mediastinal lymph nodes. However obstruction due to intravascular thrombosis is extremely uncommon. Here, we report a rare case of a 65-year-old male smoker who presented with superior vena cava syndrome and bilateral pleural and pericardial effusion with thrombotic occlusion of the superior vena cava in adenocarcinoma of the lung. He was given chemotherapy with carboplatin and gemcitabine with anticoagulant therapy.
Enhancing decoherence times in superconducting qubits via circuit design
Kaushik Mitra,C. A. R. Sá de Melo
Physics , 2010,
Abstract: We study decoherence effects in qubits coupled to environments that exhibit resonant frequencies in their spectral function. We model the coupling of the qubit to its environment via the Caldeira-Leggett formulation of quantum dissipation/coherence, and study the simplest example of decoherence effects in circuits with resonances such as a dc SQUID phase qubit in the presence of an isolation circuit, which is designed to enhance the coherence time. We emphasize that the spectral density of the environment is strongly dependent on the circuit design, and can be engineered to produce longer decoherence times. We begin with a general discussion of superconducting qubits such as the flux qubit, the Cooper pair box and the phase qubit and show that in these kinds of systems appropriate circuit design can greatly modify the spectral density of the environment and lead to enhancement of decoherence times. In the particular case of the phase qubit, for instance, we show that when the frequency of the qubit is at least two times larger than the resonance frequency of the environmental spectral density, the decoherence time of the qubit is a few orders of magnitude larger than that of the typical ohmic regime, where the frequency of the qubit is much smaller than the resonance frequency of the spectral density. In addition, we demonstrate that the environment does not only affect the decoherence time, but also the frequency of the transition itself, which is shifted from its environment-free value. Second, we show that when the qubit frequency is nearly the same as the resonant frequency of the environmental spectral density, an oscillatory non-Markovian decay emerges, as the qubit and its environment self-generate Rabi oscillations of characteristic time scales shorter than the decoherence time.
ROOT: Energy Efficient Routing through Optimized Tree in Sensor Networks
Kaushik Chakraborty,Ayon Chakraborty,Swarup Kumar Mitra,Mrinal Kanti Naskar
Mathematics , 2011,
Abstract: This paper has been withdrawn by the author due to a crucial sign error in equation 1
Spatial Phase-Sweep: Increasing temporal resolution of transient imaging using a light source array
Ryuichi Tadano,Adithya Kumar Pediredla,Kaushik Mitra,Ashok Veeraraghavan
Computer Science , 2015,
Abstract: Transient imaging or light-in-flight techniques capture the propagation of an ultra-short pulse of light through a scene, which in effect captures the optical impulse response of the scene. Recently, it has been shown that we can capture transient images using commercially available Time-of-Flight (ToF) systems such as Photonic Mixer Devices (PMD). In this paper, we propose `spatial phase-sweep', a technique that exploits the speed of light to increase the temporal resolution beyond the 100 picosecond limit imposed by current electronics. Spatial phase-sweep uses a linear array of light sources with spatial separation of about 3 mm between them, thereby resulting in a time shift of about 10 picoseconds, which translates into 100 Gfps of transient imaging in theory. We demonstrate a prototype and transient imaging results using spatial phase-sweep.
An Optimized Lifetime Enhancement Scheme for Data Gathering in Wireless Sensor Networks
Ayon Chakraborty,Kaushik Chakraborty,Swarup Kumar Mitra,M. K. Naskar
Computer Science , 2010,
Abstract: This paper has been withdrawn by the author due to a crucial sign error in equation 1
An Energy Efficient Scheme for Data Gathering in Wireless Sensor Networks Using Particle Swarm Optimization
Ayon Chakraborty,Kaushik Chakraborty,Swarup Kumar Mitra,M. K. Naskar
Computer Science , 2010,
Abstract: This paper has been withdrawn by the author due to a crucial sign error in equation 1
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