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Estimation of wind speed and wave height during cyclones

Kumar, V.S. (author)

journal article 2003

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Design wave estimation considering directional distribution of waves

Kumar, V.S. (author)

journal article 2004

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Sodium ion ordering in NaxCoO2: Electron diffraction study

Zandbergen, H.W. (author), Foo, M. (author), Xu, Q. (author), Kumar, V. (author), Cava, R.J. (author)

journal article 2004

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Variations in wave direction estimated using first and second order Fourier coefficients

Kumar, V.S. (author)

journal article 2004

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Impact of oceansat-I MSMR data on analyzed oceanic winds and waves predictions

Bhatt, V. (author), Sarkar, A. (author), Kumar, R. (author), Basu, S. (author), Agarwal, V.K. (author)

journal article 2004

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Wave interaction with a submarine pipeline in clayey soil due to random waves

Kumar, A. Vijaya (author)

journal article 2005

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Real-time optimal motion planning for autonomous underwater vehicles

Kumar, R. Prasanth (author)

journal article 2005

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Terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer

Gao, J.R. (author), Hovenier, J.N. (author), Yang, Z.Q. (author), Baselmans, J.J.A. (author), Baryshev, A. (author), Hajenius, M. (author), Klapwijk, T.M. (author), Adam, A.J.L. (author), Klaassen, T.O. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)

We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above 2?THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8?THz as local oscillator. We measure a double...

journal article 2005

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Antenna model for wire lasers

Orlova, E.E. (author), Hovenier, J.N. (author), Klaassen, T.O. (author), Kasalynas, I. (author), Adam, A.J.L. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)

journal article 2006

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Beam patterns of terahertz quantum cascade lasers with subwavelength cavity dimensions

Adam, A.J.L. (author), Kašalynas, I. (author), Hovenier, J.N. (author), Klaassen, T.O. (author), Gao, J.R. (author), Orlova, E.E. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)

The need to reach single-mode lasing and minimize at the same time the electrical dissipation of cryogenically operated terahertz quantum cascade lasers may result in small and subwavelength cavity dimensions. To assess the influence of such dimensions on the shape of the laser emission, we have measured the beam pattern of two metal-metal...

journal article 2006

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Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

Baryshev, A. (author), Hovenier, J.N. (author), Adam, A.J.L. (author), Kašalynas, I. (author), Gao, J.R. (author), Klaassen, T.O. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)

We have studied the phase locking and spectral linewidth of an ? 2.7?THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8?GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current. Phase locking has been demonstrated, resulting in...

journal article 2006

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Improved genetic algorithm inspired by biological evolution

Kumar, P. (author), Gospodaric, D. (author), Bauer, P. (author)

journal article 2007

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Hydrodynamic stability of fluid through a flexible pipe with outer rigid shroud by the energy method, Part 2: Axisymmetric ditrurbances

Kumar, Munendra (author)

journal article 2008

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Progressive design methodology for complex engineering systems based on multiobjective genetic algorithms and linguistic decision making

Kumar, P. (author), Bauer, P. (author)

This work focuses on a design methodology that aids in design and development of complex engineering systems. This design methodology consists of simulation, optimization and decision making. Within this work a framework is presented in which modelling, multi-objective optimization and multi criteria decision making techniques are used to design...

journal article 2008

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Improved Analytical Model of a Permanent-Magnet Brushless DC Motor

Kumar, P. (author), Bauer, P. (author)

In this paper, we develop a comprehensive model of a permanent-magnet brushless DC (BLDC) motor. An analytical model for determining instantaneous air-gap field density is developed. This instantaneous field distribution can be further used to determine the cogging torque, induced back electromotive force, and iron losses in the motor. The...

journal article 2008

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Phase locking of a 2.7 THz quantum cascade laser to a microwave reference

Khosropanah, P. (author), Baryshev, A. (author), Zhang, W. (author), Jellema, W. (author), Hovenier, J.N. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Paveliev, D.G. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author), Klein, B. (author), Hesler, J.L. (author)

We demonstrate the phase locking of a 2.7 THz metal–metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x12) from a microwave synthesizer at ~15 GHz....

journal article 2009

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Ground states and formal duality relations in the Gaussian core model

Cohn, H. (author), Kumar, A. (author), Schürmann, A. (author)

We study dimensional trends in ground states for soft-matter systems. Specifically, using a high-dimensional version of Parrinello-Rahman dynamics, we investigate the behavior of the Gaussian core model in up to eight dimensions. The results include unexpected geometric structures, with surprising anisotropy as well as formal duality relations....

journal article 2009

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A new approach for deriving temperature and salinity fields in the Indian Ocean using artificial neural networks

Bhaskaran, P.K. (author), Kumar, R.R. (author), Barman, R. (author), Muthalagy, R. (author)

journal article 2010

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The future of hydrology: An evolving science for a changing world

Wagener, T. (author), Sivapalan, M. (author), Troch, P.A. (author), McGlynn, B.L. (author), Harman, C.J. (author), Gupta, H.V. (author), Kumar, P. (author), Rao, P.S.C. (author), Basu, N.B. (author), Wilson, J.S. (author)

Human activities exert global-scale impacts on our environment with significant implications for freshwater-driven services and hazards for humans and nature. Our approach to the science of hydrology needs to significantly change so that we can understand and predict these implications. Such an adjustment is a necessary prerequisite for the...

journal article 2010

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Terahertz heterodyne spectrometer using a quantum cascade laser

Ren, Y. (author), Hovenier, J.N. (author), Higgins, R. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Shi, S.C. (author), Bell, A. (author), Klein, B. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)

A terahertz (THz) heterodyne spectrometer is demonstrated based on a quantum cascade laser (QCL) as a local oscillator (LO) and an NbN hot electron bolometer as a mixer, and it is used to measure high-resolution molecular spectral lines of methanol (CH3OH) between 2.913–2.918 THz. The spectral lines are taken from a gas cell containing methanol...

journal article 2010