Research Laboratory for Electronics (RLE) 2020-12-04T10:38:01Z Absorption of Microwaves by Atmospheric Gases Absorption of Microwaves by Atmospheric Gases Rosenkranz, Philip The theory of absorption of microwave emission by common atmospheric gases is reviewed. 1993-01-01T00:00:00Z Modeling stop-consonant releases for synthesis Modeling stop-consonant releases for synthesis Hanson, Helen M.; Stevens, Kenneth N. This study is part of a project leading to rule-based speech synthesis using the HLsyn synthesizer. In HLsyn, stop-consonant releases are generated by controlling the time variation of a constriction that is formed by the lips, the tongue blade, or the tongue body. In order to generate a consonant release that is perceptually acceptable and that has acoustic characteristics that match those of normal speech, it was found that the trajectory of the consonant release (cross-sectional area versus time) had to exhibit an initial rapid rise, followed by a delay in which the rise was interrupted, followed finally by a final rise. The burst at the consonant release is generated by the airflow through the constriction during the time that the rise is delayed. A model of the time course of this three-stage release of the articulator has been developed, taking into account the role of the intraoral pressure, the tapering formed by the articulator, and the glottal area. The model shows that the delay between the initial and final area increases is progressively longer for labials, alveolars, and velars, in agreement with acoustic data on the burst duration. Poster presented at the Spring 2000 Meeting of the Acoustical Society of America held in Atlanta, GA. 2011-07-27T00:00:00Z Optical Communication Through the Turbulent Atmosphere with Transmitter and Receiver Diversity, Wavefront Control, and Coherent Detection Optical Communication Through the Turbulent Atmosphere with Transmitter and Receiver Diversity, Wavefront Control, and Coherent Detection Puryear, Andrew Lee Free space optical communication through the atmosphere has the potential to provide secure, low-cost, rapidly deployable, dynamic, data transmission at very high rates. However, the deleterious e ects of turbulence can severely limit the utility of such a system, causing outages of up to 100 ms. For this thesis, we investigate an architecture that uses multiple transmitters and multiple coherent receivers to overcome these turbulence-induced outages. By controlling the amplitude and phase of the optical eld at each transmitter, based on turbulence state information fed back from the receiver, we show that the system performance is greatly increased by exploiting the instantaneous structure of the turbulence. This architecture provides a robust highcapacity free-space optical communication link over multiple spectral bands, from visible to infrared. We aim to answer questions germane to the design and implementation of the diversity optical communication architecture in a turbulent environment. We analyze several di erent optical eld spatial modulation techniques, each of which is based on a di erent assumption about the quality of turbulence state information at the transmitter. For example, we explore a diversity optical system with perfect turbulence state information at the transmitter and receiver that allocates transmit power into the spatial modes with the smallest propagation losses in order to decrease bit errors and mitigate turbulence-induced outages. Another example of a diversity optical system that we examine is a diversity optical system with only a subset of the turbulence state information: this system could allocate all power to the transmitter with the smallest attenuation. We characterize the system performance for the various spatial modulation techniques in terms of average bit error rate (BER), outage probability, and power gain due to diversity. We rst characterize the performance of these techniques in the idealized case, where the instantaneous channel state is perfectly known at both the receiver and transmitter. The time evolution of the atmosphere, as wind moves tur- 3 bules across the propagation path, can limit the ability to have perfect turbulence state knowledge at the transmitter and, thus can limit any improvement realized by optical eld spatial modulation techniques. The improvement is especially limited if the latency is large or the feedback rate is short compared to the time it takes for turbules to move across the link. As a result, we make successive generalizations, until we describe the optimal system design and communication techniques for sparse aperture systems for the most general realistic case, one with inhomogeneous turbulence and imperfect (delayed, noisy, and distorted) knowledge of the atmospheric state. Thesis Supervisor: Vincent W. S. Chan Title: Joan and Irwin M. Jacobs Professor of Electrical Engineering and Computer Science 2011-05-02T00:00:00Z Basic Atomic Physics Basic Atomic Physics Kleppner, Daniel; Pritchard, David E.; Ketterle, Wolfgang; DeVries, Joel C.; Ducas, Theodore W.; Holley, Jeffrey R.; Spellmeyer, Neal W.; Smith, Edward T.; Rubenstein, Richard A.; Kokorowski, David A.; Roberts, Tony; Yao, Huan; Dhirani, Al-Amin; Bradley, Michael P.; Rainville, Simon; Thompson, James R.; Nguyen, Roland N.; Porto, James V.; Miesner, Hans-Joachim; Raman, Chandra S.; Stenger, J?rn; Townsend, Christopher G.; Onofrio, Roberto; Andrews, Michael R.; Chikkatur, Ananth P.; Durfee, Dallin S.; Inouye, Shin; Kuklewicz, Christopher E.; Stamper-Kurn, Dan M.; Vogels, Johnny M. Contains reports on five research projects. 1997-01-01T00:00:00Z 狠狠躁天天躁中文字幕_日韩欧美亚洲综合久久_漂亮人妻被中出中文字幕