المؤلفون: Pozderac, Jonathan¹, Johnson, Joel¹, Yardim, Caglar¹, Merrill, Craig², De Paolo, Tony³, Terrill, Eric³, Ryan, Frank⁴, Frederickson, Paul⁵

المصدر: IEEE Transactions on Antennas & Propagation. May2018, Vol. 66 Issue 5, p2545-2556. 12p.

مصطلحات موضوعية: RADIO wave propagation, TRANSMITTERS (Communication), RECEIVING antennas, WAVEGUIDE antennas

مصطلحات جغرافية: CALIFORNIA

مستخلص: Recent experimental campaigns provided the opportunity to measure radio wave propagation and atmospheric conditions with the $X$ -band beacon-receiver (XBBR) array system. The system consists of vertical arrays of transmitters and receivers for measuring the $X$ -band propagation. Measurements near the sea surface can be used to obtain information regarding the refractivity profile of the lower atmosphere. Since ducted propagation acts as a leaky waveguide, the vertical array elements in various transmit and receive height combinations effectively observe differing combinations of the modal components propagating in the duct, the use of multiple combinations improves the estimation of duct properties. The aforementioned measurement campaigns occurred near the coast of southern California; the SoCal 2013 experiment and the Scripps Pier Campaign. During both campaigns, the propagation loss recorded at each of the receivers from each of the transmitters, standardized by the total received power, was compared to variable terrain radio parabolic equation model predictions in order to estimate the evaporation duct height (EDH). Point meteorological data were recorded and used with the Navy Atmospheric Vertical Surface Layer Model to obtain in situ measurements of the EDH. Comparisons show strong correlation between EDH values inferred from XBBR measurements and meteorological information. [ABSTRACT FROM PUBLISHER]

: Copyright of IEEE Transactions on Antennas & Propagation is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Taborda, Ricardo, Bielak, Jacobo

المصدر: Bulletin of the Seismological Society of America; Feb2013, Vol. 103 Issue 1, p131-156, 26p

مصطلحات موضوعية: EARTHQUAKES, SEISMOLOGY, PREDICTION models, SIMULATION methods & models, EARTHQUAKE magnitude, ELASTIC wave propagation, FINITE element method

مصطلحات جغرافية: CHINO Hills (Calif.), CALIFORNIA

مستخلص: We present a simulation of the 2008 Mw 5.4 Chino Hills earthquake for a maximum frequency up to 4 Hz and a minimum shear-wave velocity down to 200 m/s and perform a validation study comparing data obtained from seismic networks with simulation synthetics on more than 300 recording stations. The simulation was done using a parallel-computing code for earthquake simulations that implements a finite-element solution to anelastic wave propagation in heterogeneous media. The source model corresponds to that of an independent inversion study, and the material model used is a community velocity model (CVM) developed by the Southern California Earthquake Center (SCEC). Our results for the goodness-of-fit measure of the syn-thetics indicate that, from a regional perspective, the simulation starts to deviate from the data at frequencies above 1 and 2 Hz. At particular locations or station clusters, however, the synthetics yield very good results, even at frequencies between 2 and 4 Hz. The best results are obtained between 0.1 and 0.25 Hz over the entire region and up to 1 Hz within the major basins. These and other results from comparisons at boreholes, biases of the peak surface response, and the differences in the strong-phase duration of the waveforms and the arrival time of P waves suggest a strong sensitivity to seismic velocities. In particular, the CVM used seems to misrepresent the shallow soil deposits and overestimate seismic velocities in the upper layers out-side the basins. These observations are helpful in identifying regions where the veloc-ity model may need to be revised. Overall, this study shows that extending the maximum frequency for deterministic earthquake simulations beyond 1 Hz is an effort worth pursuing. [ABSTRACT FROM AUTHOR]

: Copyright of Bulletin of the Seismological Society of America is the property of Seismological Society of America and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Orzech, Mark D.¹ mark.orzech.ctr@nrlssc.navy.mil, Reniers, Ad J.H.M.², Thornton, Edward B.³, MacMahan, Jamie H.³

المصدر: Coastal Engineering. Sep2011, Vol. 58 Issue 9, p890-907. 18p.

مصطلحات موضوعية: *SHORELINE monitoring, *RIP currents, *VLF radio wave propagation, *SEDIMENT transport, *WATER levels, *BANKS (Oceanography), *ALTITUDE measurements, *SIMULATION methods & models, *OSCILLATIONS, *BAYS

مصطلحات جغرافية: CALIFORNIA

مستخلص: Abstract: The formation of beach megacusps along the shoreline of southern Monterey Bay, CA, is investigated using time-averaged video and simulated with XBeach, a recently developed coastal sediment transport model. Investigations focus on the hydrodynamic role played by the bay''s ever-present rip channels. A review of four years of video and wave data from Sand City, CA, indicates that megacusps most often form shoreward of rip channels under larger waves (significant wave height (H s )=1.5–2.0m). However, they also occasionally appear shoreward of shoals when waves are smaller (H s ~1m) and the mean water level is higher on the beach. After calibration to the Sand City site, XBeach is shown to hindcast measured shoreline change moderately well (skill=0.41) but to overpredict the erosion of the swash region and beach face. Simulations with small to moderate waves (H s =0.5–1.2m) suggest, similar to field data, that megacusps will form shoreward of either rip channels or shoals, depending on mean daily water level and pre-existing beach shape. A frequency-based analysis of sediment transport forcing is performed, decomposing transport processes to the mean, infragravity, and very-low-frequency (VLF) contributions for two highlighted cases. Results indicate that the mean flow plays the dominant role in both types of megacusp formation, but that VLF oscillations in sediment concentration and advective flow are also significant. [Copyright &y& Elsevier]

المؤلفون: Sternstein, Aliya

المصدر: Federal Computer Week; 5/22/2006, Vol. 20 Issue 16, p50-51, 2p, 1 Color Photograph

مصطلحات موضوعية: CELL phone systems, LABORATORIES, RADIO wave propagation

مصطلحات جغرافية: CALIFORNIA

الشركة/الكيان: LGC Wireless Inc., CINGULAR Wireless LLC

مستخلص: The article focuses on the installation of an indoor cellular system from LGC Wireless at the Lawrence Berkeley National Laboratory's campus in California. Cellular coverage at the campus had been affected by its cavernous landscape and concrete and steel infrastructures that obstructed signals. The indoor cellular system was installed within six months. It is similar to a sprinkler system that sprays radio waves. The increasing number of facilities at the campus will require more extensions. One limitation of the system is that it supports only Cingular Wireless subscribers.

المصدر: IEEE Antennas & Propagation Magazine; Aug2013, Vol. 55 Issue 4, p225-225, 1p

مصطلحات موضوعية: ELECTRONIC antenna conferences, RADIO wave propagation, MECHANICS (Physics), CONFERENCES & conventions

مصطلحات جغرافية: MISSISSIPPI, CALIFORNIA, MANITOBA

الشركة/الكيان: INSTITUTE of Electrical & Electronics Engineers

مستخلص: The article offers brief information on several symposiums titled "IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting" to be held in several states of the U.S. including California, Manitoba and Mississippi from 2014 to 2017.