Now showing items 1359-1378 of 2173

    • Numerical application of concepts from confocal microscopy to holography and other coherent imaging systems 

      Byrd, Marc Jeston (1994)
      A novel methodology based on the scanning confocal microscope is presented which enables a general solution of the depth resolution problem in holography and other coherent imaging schemes. The method does not depend on a ...
    • Numerical calculation of interaction forces between paramagnetic colloids in two-dimensional systems 

      Du, Di; Toffoletto, Frank; Biswal, Sibani Lisa (2014)
      Typically the force between paramagnetic particles in a uniform magnetic field is described using the dipolar model, which is inaccurate when particles are in close proximity to each other. Instead, the exact force between ...
    • Numerical Estimates of Generalized Dimensions D_q for Negative q 

      Riedi, Rudolf H. (1996-01-01)
      Usual fixed-size box-counting algorithms are inefficient for computing generalized fractal dimensions D(<i>q</i>) in the range of <i>q</i><0. In this Letter we describe a new numerical algorithm specifically devised to ...
    • Numerical investigation of coexisting high and low amplitude responses and safe basin erosion for a coupled linear oscillator and nonlinear absorber system 

      Eason, Richard Parker; Dick, Andrew James; Nagarajaiah, Satish (2014)
      Over the last half century, numerous nonlinear variants of the tuned mass damper have been developed in order to improve attenuation characteristics. In the present study, the performance of a linear oscillator and an ...
    • A numerical investigation of snap-through in a shallow arch-like model 

      Chandra, Yenny; Stanciulescu, Ilinca; Virgin, Lawrence N.; Eason, Thomas G.; Spottswood, Stephen M. (2013)
      Slender curved structures may experience a loss of stability called snap-through, causing the curvature on part or all of the structure to invert inducing fatigue damage. This paper presents a framework for analyzing the ...
    • Numerical pathologies in snap-through simulations 

      Chandra, Yenny; Stanciulescu, Ilinca; Eason, Thomas; Spottswood, Michael (2012)
      Aircraft structures operating in severe environments may experience snap-through, causing the curvature on part or all of the structure to invert inducing fatigue damage. This paper examines the performance of beam and ...
    • Observation and modeling of the evolution of Texas power plant plumes 

      Zhou, W.; Cohan, D.S.; Pinder, R.W.; Neuman, J.A.; Holloway, J.S.; Peischl, J.; Ryerson, T.B.; Nowak, J.B.; Flocke, F.; Zheng, W.G. (2012)
      During the second Texas Air Quality Study 2006 (TexAQS II), a full range of pollutants was measured by aircraft in eastern Texas during successive transects of power plant plumes (PPPs). A regional photochemical model is ...
    • Observation of Forbidden Exciton Transitions Mediated by Coulomb Interactions in Photoexcited Semiconductor Quantum Wells 

      Rice, W.D.; Kono, J.; Zybell, S.; Winnerl, S.; Bhattacharyya, J.; Schneider, H.; Helm, M.; Ewers, B.; Chernikov, A.; Koch, M.; Chatterjee, S.; Khitrova, G.; Gibbs, H.M.; Schneebeli, L.; Breddermann, B.; Kira, M.; Koch, S.W. (2013)
      We use terahertz pulses to induce resonant transitions between the eigenstates of optically generated exciton populations in a high-quality semiconductor quantum well sample. Monitoring the excitonic photoluminescence, ...
    • Observing the interplay between surface and bulk optical nonlinearities in thin van der Waals crystals 

      Deckoff-Jones, Skylar; Zhang, Jingjing; Petoukhoff, Christopher E.; Man, Michael K.L.; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel M.; Talbayev, Diyar; Madéo, Julien; Dani, Keshav M. (2016)
      Van der Waals materials, existing in a range of thicknesses from monolayer to bulk, allow for interplay between surface and bulk nonlinearities, which otherwise dominate only at atomically-thin or bulk extremes, respectively. ...
    • On a Class of Minimum Energy Controls Related to Spline Functions 

      Netravali, Arun N.; de Figueiredo, Rui J.P. (1975-07-20)
      The problem of determining a minimum energy control for a dynamically interconnected set of p single-input single-output finite-dimensional linear time-varying dynamical systems, for which the outputs are constrained to ...
    • On Beamforming with Finite Rate Feedback in Multiple Antenna Systems 

      Mukkavilli, Krishna Kiran; Sabharwal, Ashutosh; Erkip, Elza; Aazhang, Behnaam (2003-10-20)
      In this paper, we study a multiple antenna system where the transmitter is equipped with quantized information about instantaneous channel realizations. Assuming that the transmitter uses the quantized information for ...
    • On Capacity of Gaussian â Cheapâ Relay Channel 

      Khojastepour, Mohammad; Sabharwal, Ashutosh; Aazhang, Behnaam (2003-12-01)
      In this paper, we derive the capacity of the Gaussian degraded â cheapâ relay channel, consisting of nodes using â cheapâ radios operating in TDD mode when transmitting and sending in the same frequency band. The TDD ...
    • On Channel State Information in Multiple Antenna Block Fading Channels 

      Sabharwal, Ashutosh; Erkip, Elza; Aazhang, Behnaam (2000-11-20)
      Motivated by large capacity gains in multiple antenna systems when perfect channel state information is available at both receiver and transmitter, we examine the achievable rates of channel measurement based techniques. ...
    • On computing minimal independent support and its applications to sampling and counting 

      Ivrii, Alexander; Malik, Sharad; Meel, Kuldeep S.; Vardi, Moshe Y. (2015)
      Constrained sampling and counting are two fundamental problems arising in domains ranging from artificial intelligence and security, to hardware and software testing. Recent approaches to approximate solutions for these ...
    • On Design Criteria and Construction of Non-coherent Space-Time Constellations 

      Borran, Mohammad Jaber; Sabharwal, Ashutosh; Aazhang, Behnaam; Johnson, Don (2002-07-20)
      We consider the problem of digital communication in a Rayleigh flat fading environment using a multiple antenna system, when both the transmitter and the receiver are unaware of the channel coefficients. Using Stein's lemma ...
    • On Design Criteria and Construction of Non-coherent Space-Time Constellations 

      Borran, Mohammad Jaber; Sabharwal, Ashutosh; Aazhang, Behnaam (2003-10-20)
      We consider the problem of digital communication in a Rayleigh flat fading environment using a multiple-antenna system, when the channel state information is available neither at the transmitter nor at the receiver. It ...
    • On Diversity and Multiplexing Gain of Multiple Antenna Systems with Transmitter Channel Information 

      Khoshnevis, Ahmad; Sabharwal, Ashutosh (2004-10-01)
      We quantify the multiplexing-diversity tradeoff of a multiple-input multiple-output (MIMO) system, when the channel state information (CSI) is known perfectly at the receiver and partially at the transmitter. The partial ...
    • ON EFFICIENT DIGITAL FILTERING 

      CHU, SHUNI (1981)
      Part I: Multistage Multirate Digital Filtering. A theorem is introduced which is useful in deriving equivalent multirate filter structures. Frequency responses of multistage multirate filters are derived and defined in ...
    • On Joint Distributions for Arbitrary Variables 

      Baraniuk, Richard G.; Cohen, Leon (1995-01-01)
      There has been considerable interest in the problem of joint representations for variables other than time and frequency. In this letter we compare the methods of Cohen and of Baraniuk and Jones and show their equivalence ...
    • On Limits of Antenna Packing in Low Power Systems 

      Muharemovic, Tarik; Sabharwal, Ashutosh; Aazhang, Behnaam (2004-09-01)
      We evaluate spectral efficiency limits of low power portable communication devices which are only constrained by fixed transceiver aperture G "subset&equal" real<sup>3</sup> for mounting antennas. A new notion of ...