WorldWideScience

Sample records for broadsides

  1. Colonial Broadsides: A Student-Created Play. [Lesson Plan].

    Science.gov (United States)

    2002

    "Broadsides" are notices written on disposable, single sheets of paper printed on one side only, intended to have an immediate impact on readers. Broadsides had an impact in colonial America--they delivered the latest news and much more: government proclamations, public service announcements, opinion papers, advertisements, and entertainment…

  2. Enhanced Skewed Load and Broadside Power Reduction in Transition Fault Testing

    OpenAIRE

    A. Jyothi; Ms. P.Priyadharshika

    2014-01-01

    This Paper Proposes the T-algorithm technique to optimize the testing Skewed Load and Broadside architecture. And the architecture used to the compare the test pattern results. In this architecture, T-algorithm used to optimize the testing architecture. This architecture compare the test pattern output for the required any type of combinational architecture. The optimization process mainly focused by gate optimization for secure architecture. The proposed system to use the T-algorithm, to opt...

  3. Substrate integrated waveguide filters with broadside-coupled complementary split ring resonators

    OpenAIRE

    Huang, L.; Robertson, ID; Wu, W.; Yuan, N

    2013-01-01

    Four designs of substrate integrated waveguide (SIW) filter employing integrated broadside-coupled complementary split-ring resonators are compared. By changing the orientation of the rings, four types of SIW unit cell are proposed and investigated and it is shown that, for one particular topology, two poles and two zeros can be realised with a single unit cell. Bandpass filters based on the proposed resonators coupled by evanescent-mode SIW sections have been fabricated and tested. The propo...

  4. Decoupling crossover in asymmetric broadside coupled split-ring resonators at terahertz frequencies

    DEFF Research Database (Denmark)

    Keiser, G. R.; Strikwerda, Andrew; Fan, K.; Young, V.; Zhang, X.; Averitt, R. D.

    2013-01-01

    We investigate the electromagnetic response of asymmetric broadside coupled split-ring resonators (ABC-SRRs) as a function of the relative in-plane displacement between the two component SRRs. The asymmetry is defined as the difference in the capacitive gap widths (Δg) between the two resonators...... inductive coupling. However, for ABC-SRRs, in-plane shifting between the two resonators by more than 0.375 Lo (Lo= SRR sidelength) results in a transition to a response with two resonant modes, associated with decoupling in the ABC-SRRs. For increasing Δg, the decoupling transition begins at the same...

  5. Substrate integrated waveguide filters with face-to-face broadside-coupled complementary split ring resonators

    OpenAIRE

    Huang, L.; Robertson, ID; Yuan, N

    2013-01-01

    Novel substrate integrated waveguide (SIW) filters using face-to-face oriented broadside-coupled complementary split ring resonators (BC-CSRRs) are presented in this paper. The SIW with the conventional BC-CSRR resonator pairs is first investigated. By removing the metal strip between the two back-to-back rings of the BC-CSRR pair, a modified BC-CSRR pair which shows a significantly improved spurious suppression and a wider rejection bandwidth is then proposed. SIW bandpass filters based on t...

  6. Miniaturized Dielectric Resonator Antenna with Broadside Radiations for Ultra-Wideband Applications

    Directory of Open Access Journals (Sweden)

    M. Krishna Kumar

    2014-03-01

    Full Text Available This work carries a novel miniaturized Dielectric Resonator Antenna (DRA that has radiations in the broadside region. The antenna was designed and simulated using Advanced Design System (ADS software. The antenna proposed consists of a solid ‘A’ shaped dielectric resonator mounted on the edge of the ground plane to reduce the overall volume and excited by using a microstrip feed line. An air gap is introduced between the resonator and the ground plane inorder to improve the bandwidth. This antenna showed a high efficiency & gain over the proposed radiating frequency. Experimental results show that the antenna radiates at a frequency of 8.9 GHz with a return loss of -19.93 dB. This antenna can also be used alongside with portable wireless devices.

  7. Savannah River waste plant takes another broadside

    International Nuclear Information System (INIS)

    This article is a discussion of Government Accounting Office findings related to the high-level waste disposal facilities, and in particular the Defense Waste Processing Facility, at Savannah River. Cost and schedule problems are noted, and the report concluded that ineffective management, both by DOE personnel and M ampersand AO contractor personnel, was a principal factor contributing to these problems at the DWPF and supporting facilities

  8. Broadside Ballads: Social Consciousness in Song

    Science.gov (United States)

    Junda, Mary Ellen

    2013-01-01

    This article highlights a group ballad project which is a part of student experiences in Sing and Shout!, a course that integrates academic study with singing and song writing to develop a deeper understanding of problems in society. Students explore the intricacies of song composition and social consciousness drawn from past events that reflect…

  9. Russia coordinates new broadside against OSCE / Liz Fuller

    Index Scriptorium Estoniae

    Fuller, Liz

    2004-01-01

    SRÜ maade poolt 8. juulil 2004 Viinis tehtud avaldusest, mille kohaselt sekkub Euroopa Julgeoleku- ja Koostööorganisatsioon (OSCE) riikide siseasjadesse ning rakendab topeltstandardeid. Avaldusega ei ühinenud Gruusia ja Aserbaidžaan

  10. A novel auxetic broadside defensive structure for naval ships%舰艇新型宏观负泊松比效应蜂窝舷侧防护结构

    Institute of Scientific and Technical Information of China (English)

    杨德庆; 马涛; 张梗林

    2015-01-01

    提出一种具有宏观负泊松比效应的新型蜂窝舷侧防护结构,通过对负泊松比效应蜂窝胞元特殊结构构型设计,实现中等弹速下良好抗爆抗冲击性能.利用有限元动力学分析软件,研究鱼雷或导弹水下对舷侧防护结构的撞击侵入和穿透过程,对比研究了不同蜂窝构型、材料、胞元尺寸和胞壁厚度对舷侧结构抗冲击性能的影响.结果表明,蜂窝防护结构具有良好的抗冲击性能,负泊松比蜂窝构型较正泊松比蜂窝构型抗冲击性能更优.

  11. Numerical study of rowing hydrofoil performance at low Reynolds numbers

    Science.gov (United States)

    Chung, M.-H.

    2008-04-01

    In this paper, the hydrodynamic performance of a 2-D flat-plate hydrofoil in rowing motion is numerically studied by a Cartesian grid method with the cut-cell approach. Adaptive mesh refinement is used to save on the number of mesh cells without harming spatial resolution in critical regions. The rowing kinematics of the hydrofoil is the same for all simulations in this work. The design parameters studied are the reduced frequency of the rowing motion, the heave amplitude, and the time lags of the feathered-to-broadside rotation and the broadside-to-feathered rotation. Results show that larger thrust and efficiency can be attained if the feathered-to-broadside rotation is started right after the beginning of the power stroke and the broadside-to-feathered rotation is finished right before the end of the power stroke. Finally, both the thrust and the efficiency increase with Reynolds number.

  12. Higher order mode of a microstripline fed cylindrical dielectric resonator antenna

    Science.gov (United States)

    Kumar, A. V. Praveen

    2016-03-01

    A microstrip transmission line can be used to excite the broadside radiating mode of a cylindrical dielectric resonator antenna (CDRA). The same is found to excite considerably well a higher order mode (HOM) as well. However unlike the broadside mode, the higher order mode gives distorted radiation pattern which makes this mode less useful for practical applications. The cause of distortion in the HOM radiation and the dependence of HOM coupling on the microstrip feed line are explored using HFSS simulations.

  13. IMPROVED ALGORITHM FOR STRIPMAP SAR IMAGING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper proposes a calibrated method for quasi-broadside side-looking mode SAR imaging with small squint angle and an improved method named as phase alignment algorithm of subaperture reference signal. The calibrated method adopts subaperture spotlighting algorithm of broadside mode to image the real data of quasi-broadside mode SAR, then based on the obtained image the small squint angle is estimated and the calibrated subaperture spotlighting algorithm of squint mode is employed to obtain the final image. The calibrated method can calibrate the abnormal region and obtain the correct image. The phase alignment algorithm of subaperture reference signal adjusts phases of respective subaperture reference signals in order to make them be in phase and constructs a new spotlighting window function for SAR imaging. Theoretical analysis shows that with the same sample data, the improved method can increase SAR imaging area in azimuth dimension. The methods are verified by the results of computer simulation.

  14. Rolling With Simplified Stream Function Velocity and Strain Rate Vector Inner Product

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The dual-stream function velocity field is reduced in order to analyze two-dimensional plate broadside roll- ing in roughing. The strain rate vector inner product and integral mean value theorem, as well as coqine vector inner product are used respectively in plastic deformation power, friction losses and shear power. A theoretical solution of roll torque and separating force for the rolling is obtained and the calculated results by the solution are compared with those measured in broadside rolling on-line. It shows that both the force and torque calculated are higher than those of measured, but the maximum relative error between them is no more than 11%.

  15. Píseň k patronům Moravy „Slávo markrabství“ v rukopisu z roku 1906. Ke studiu české cyrilometodějské tradice v lidovém duchovním zpěvu a ke vztahu kontrafakt mezi ústní tradicí a písemnictvím

    Czech Academy of Sciences Publication Activity Database

    Frolcová, Věra

    2014-01-01

    Roč. 101, č. 2 (2014), 129-148. ISSN 0009-0794 Institutional support: RVO:68378076 Keywords : St. Cyril and Methodius * Czech folk spiritual song * oral tradition * manuscript hymn-book * printed sheets with broadside ballads * contrafactum * Baroque and reception of songs * ethno-musicology * hymnography * Vnorovy Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 0.094, year: 2012

  16. Vánoční ukolébavka v rukopisném kancionálu kuželovského rektora a v lidových hrách. K perspektivám regionálních studií.

    Czech Academy of Sciences Publication Activity Database

    Frolcová, Věra

    2015-01-01

    Roč. 49, č. 1 (2015), s. 7-22. ISSN 0862-1209 Institutional support: RVO:68378076 Keywords : Christmas lullaby * ethnomusicology * Kuželov * reception of Baroque song * Christmas plays * broadsides printing * handwritten hymn-book Subject RIV: AC - Archeology, Anthropology, Ethnology

  17. Odraz kultu Panny Marie Svatohorské v kramářské produkci

    Czech Academy of Sciences Publication Activity Database

    Holubová, Markéta

    Praha: Etnologický ústav AV ČR, 2014 - (Holubová, M.; Suchomelová, M.), s. 59-79 ISBN 978-80-87112-88-5 Institutional support: RVO:68378076 Keywords : Broadside print * Czech lands * cult of Virgin Mary * song of pilgrimage Subject RIV: AC - Archeology, Anthropology, Ethnology

  18. Through-the-wall detection of slow-moving personnel

    Science.gov (United States)

    Martone, Anthony; Ranney, Kenneth; Innocenti, Roberto

    2009-05-01

    This paper presents a time-domain, Moving-Target-Indication (MTI) processing formulation for detecting slow-moving personnel behind walls. The proposed time-domain MTI processing formulation consists of change detection and tracking algorithms. We demonstrate the effectiveness of the MTI processing formulation using data collected by the Army Research Laboratory's (ARL's), Ultra-Wideband (UWB), Synchronous Impulse Reconstruction (SIRE) radar. During the collection of the data, the SIRE radar remains stationary and is positioned broadside to the wall and 38 degrees off the broadside position. We have collected data for multiple operational scenarios including: personnel walking inside wood and cinderblock structures, personnel walking in linear and non-linear trajectories, and multiple personnel walking within the building structure. We analyze the characteristics of moving target signatures for the multiple operational scenarios and describe the detection and tracking algorithms implemented to exploit them.

  19. Imagined States

    OpenAIRE

    giudice, Luisa Del; Porter, Gerald

    2001-01-01

    An international ensemble of folklore scholars looks at varied ways in which national and ethnic groups have traditionally and creatively used imagined states of existence-some idealizations, some demonizations-in the construction of identities for themselves and for others. Drawing on oral traditions, especially as represented in traditional ballads, broadsides, and tale collections, the contributors consider fertile landscapes of the mind where utopias overflow with bliss and abundance, ste...

  20. A method for testing handgun bullets in deer

    OpenAIRE

    Courtney, Michael; Courtney, Amy

    2007-01-01

    Using service handguns to test bullets in deer is problematic because of velocity loss with range and accuracy giving sub-optimal shot placement. An alternate method is presented using a scoped muzzleloader shooting saboted handgun bullets to allow precise (within 2" in many cases) shot placement for studying terminal ballistics in a living target. Deer are baited to a known range and path obstructions are used to place the deer broadside to the shooter. Muzzleloading powder charges provide a...

  1. 'A most detestable crime'. Representations of Rape in the Popular Press of Early Modern England

    OpenAIRE

    Donatella Pallotti

    2012-01-01

    In early modern England the legal definition of rape underwent an important revision and gradually, from crime against property, rape became a crime against the person. While reflecting the classical, medieval and biblical assumptions, the period brought about new concerns. The purpose of this article is to explore representations of rape in a variety of popular texts of the English early modern period, by focussing attention on broadside ballads, cheap pamphlets as well as accounts of trials...

  2. Improvement of 5.8 GHz Band Patch Antenna with Metamaterial

    Institute of Scientific and Technical Information of China (English)

    Nam-ki LEE; Seung-in YANG

    2010-01-01

    A patch antenna,a metamaterial patch antenna and a proposed metamaterial patch antenna,are simulated and compared.Simulation results show that the proposed antenna can concentrate so well radiation energy into broadside direction that the antenna gain is increased and the side lobe level is decreased.Therefore,the gain of the proposed metamaterial patch antenna is improved by 2 dB than that of the ordinary metamaterial patch anterma.

  3. New Polarization Basis for Polarimetric Phased Array Weather Radar: Theory and Polarimetric Variables Measurement

    OpenAIRE

    Jian Dong; Qingfu Liu; Xuesong Wang

    2012-01-01

    A novel scheme is developed for mitigating measurement biases in agile-beam polarimetric phased array weather radar. Based on the orthogonal Huygens source dual-polarized element model, a polarization measurement basis for planar polarimetric phased array radar (PPAR) is proposed. The proposed polarization basis is orthogonal to itself after a 90° rotation along the array’s broadside and can well measure the characteristics of dual-polarized element. With polarimetric measurements being under...

  4. Design of Square Shaped Miniaturized Split Ring Resonators

    Directory of Open Access Journals (Sweden)

    Najuka Hadkar,

    2015-05-01

    Full Text Available Microwaves are constantly experiencing changes for many years. Microwave circuits use microstrip lines because it allows easy integration of active and passive surface mount components and it is less costly. In addition to a large number of benefits, microstrip lines have some disadvantages such as narrow-band loss, interference and low efficiency. To overcome the disadvantages, metamaterials are introduced. The proposed work shows various concentric U-shaped multi-split ring resonators(SRRs metamaterial structures with & without broadside coupling. As compared to the conventional split ring resonators , broadside coupled resonators shows decrease in the LC resonance frequency and provide an electrically small and easy-tofabricate alternative to the present multi-band metamaterial structures. The multi-band magnetic resonator topologies are simulated using CST Microwave Studio (MWS to compute and compare their electrical sizes. Different types of U-shaped structures with inner and outer rings of SRR are used to realize transmission spectra, resonant frequencies and electrical sizes. This topology has the flexibility of adjusting the resonance frequencies by changing the design parameters such as the gap width, metal width and inter-ring distances. The broadside-coupled multiple U-Shaped magnetic resonator topology is considered to be a useful contribution to multi-band metamaterial research applications.

  5. Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays

    Science.gov (United States)

    Trucco, Andrea; Traverso, Federico; Crocco, Marco

    2015-01-01

    For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches. PMID:26066987

  6. Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Andrea Trucco

    2015-06-01

    Full Text Available For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed. In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

  7. Muž a žena v kontextu kramářské produkce

    Czech Academy of Sciences Publication Activity Database

    Holubová, Markéta

    Bratislava: Zväz múzeí na Slovensku, 2013 - (Nádaská, K.), s. 158-165 ISBN 978-80-971506-7-9. [Muž a žena - vzťahové súvislosti v kontexte múzejných zbierok. Etnológ a múzeum /17./. Bratislava (SK), 01.10.2014-03.10.2014] Institutional support: RVO:68378076 Keywords : gender study * broadside print * Bohemia Subject RIV: AC - Archeology, Anthropology, Ethnology

  8. Análisis y diseño de antena Leaky-Wave CRLH y de superficie selectiva en frecuencia para el control de los campos radiados

    OpenAIRE

    Pereira Sánchez, Salvadora

    2013-01-01

    En este proyecto se balanceará una antena LW basada en las celdas unitarias microstrip CRLH idénticas desarrolladas en [14] para su radiación en broadside a 10GHz, y se analizarán sus características de radiación. El objetivo fundamental será la reducción de los lóbulos laterales del diagrama de radiación de la antena mencionada, mediante el diseño no uniforme de la longitud y periodicidades de los slots que componen una superficie selectiva en frecuencia localizada sobre la antena, que ju...

  9. Reducing losses and dispersion effects in multilayer metamaterial tunnelling devices

    International Nuclear Information System (INIS)

    This paper focuses on reduction of losses and dispersion effects on tunnelling through waveguides filled with metamaterial. It will be shown that these unwanted effects could be reduced by dividing the metamaterial into several regions separated by air slabs. In the first part, these effects will be studied for isotropic left-handed media (LHM). Later this will be substituted by an anisotropic magnetic medium which will lead to a practical realization with broadside coupled split ring resonators (BC-SRRs). Finally, it is shown that quasi-perfect tunnelling is possible, even in the presence of unavoidable losses and dispersion in the metamaterial

  10. Microstrip and printed antenna design

    CERN Document Server

    Bancroft, Randy

    2009-01-01

    The approach in this book is historical and practical. It covers abasic designsa in more detail than other microstrip antenna books that tend to skip important electrical properties and implementation aspects of these types of antennas. Examples include: quarter-wave patch, quarter by quarter patch, detailed design method for rectangular circularly polarized patch, the use of the TM11 (linear and broadside CP), TM21 (monopole CP pattern) and TM02 (monopole linear) circular patch modes in designs, dual-band antenna designs which allow for independent dual-band frequencies. Limits on broadband m

  11. War and the Media in Border Minstrelsy: The Ballad of Chevy Chase (book chapter)

    OpenAIRE

    Perry, Ruth

    2010-01-01

    The ballad of Chevy Chase is a very old ballad, probably dating back to the fifteenth century and referring to events that transpired in the middle of that century or even back to the fourteenth century. Appreciated by writers and singers from feudal times to the age of Enlightenment, this ballad also crossed the line from oral culture to manuscript and printed text and back again—moving back and forth between broadside and song, sometimes part of a living tradition and sometimes an antiquari...

  12. Miniaturised self-resonant split-ring resonator antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2009-01-01

    A self-resonant miniaturized antenna composed of a broadside-coupled split-ring resonator (SRR) and an excitation arc-shaped monopole is presented. The size of the antenna and its resonance frequency is essentially defined by the SRR dimensions and geometry, while the input resistance at the...... resonance is governed by the arc length of the monopole. Numerical and experimental results are presented for an antenna configuration of 1/23.4 wavelength in diameter (ka~0.134). The antenna is tuned to 50 ohms without any matching network, and its efficiency is measured to be 17.5%....

  13. Miniaturised self-resonant split-ring resonator antenna

    OpenAIRE

    Kim, Oleksiy S.; Breinbjerg, Olav

    2009-01-01

    A self-resonant miniaturized antenna composed of a broadside-coupled split-ring resonator (SRR) and an excitation arc-shaped monopole is presented. The size of the antenna and its resonance frequency is essentially defined by the SRR dimensions and geometry, while the input resistance at the resonance is governed by the arc length of the monopole. Numerical and experimental results are presented for an antenna configuration of 1/23.4 wavelength in diameter (ka~0.134). The antenna is tuned to ...

  14. Acoustic metafluid with anisotropic mass density and tunable sound speed: An approach based on suspensions of orientable anisotropic particles

    Science.gov (United States)

    Seitel, Mark; Tse, Stephen; Shan, Jerry

    2011-11-01

    We investigate liquid suspensions of micron-scale, anisotropic particles as potential acoustic metafluids having anisotropic and actively controllable acoustic properties. The effective mass density (and hence the sound propagation speed) of these metafluids can vary because the added mass of an anisotropic particle suspended in the fluid changes with the particle's orientation relative to the direction of the wave propagation. A suspension with disc-like particles oriented broadside to the direction of wave propagation is thus expected to have higher effective inertia and lower sound speed than a suspension with particles with end-on alignment. To test these predictions, sound speed is measured with a time-of-flight method in suspensions of micron-size nickel flakes suspended in oil, with and without magnetic-field-induced alignment of the particles. The sound speed, relative to the unaligned case, is found to decrease for particles oriented broadside to the sound wave, and increase for edgewise alignment. We also investigate the frequency dependence of the effective sound speed, since the added mass effect is expected to diminish as the flow becomes steady at low frequencies. The experimental results are compared to the predictions of a model proposed by Ahuja & Hardee (J. Acoust. Soc. Am 1978) for the acoustic properties of aligned oblate-spheroid suspensions.

  15. Theory of a Directive Optical Leaky Wave Antenna Integrated into a Resonator and Enhancement of Radiation Control

    CERN Document Server

    Guclu, Caner; Boyraz, Ozdal; Capolino, Filippo

    2013-01-01

    We provide for the first time the detailed study of the radiation performance of an optical leaky wave antenna (OLWA) integrated into a Fabry-P\\'erot resonator. We show that the radiation pattern can be expressed as the one generated by the interference of two leaky waves counter-propagating in the resonator leading to a design procedure for achieving optimized broadside radiation, i.e., normal to the waveguide axis. We thus report a realizable implementation of the OLWA made of semiconductor and dielectric regions. The theoretical modeling is supported by full-wave simulation results, which are found to be in good agreement. We aim to control the radiation intensity in the broadside direction via excess carrier generation in the semiconductor regions. We show that the presence of the resonator can provide an effective way of enhancing the radiation level modulation, which reaches values as high as 13.5 dB, paving the way for novel promising control capabilities that might allow the generation of very fast op...

  16. Chapter 3 – Phenomenology of Tsunamis: Statistical Properties from Generation to Runup

    Science.gov (United States)

    Geist, Eric L.

    2015-01-01

    Observations related to tsunami generation, propagation, and runup are reviewed and described in a phenomenological framework. In the three coastal regimes considered (near-field broadside, near-field oblique, and far field), the observed maximum wave amplitude is associated with different parts of the tsunami wavefield. The maximum amplitude in the near-field broadside regime is most often associated with the direct arrival from the source, whereas in the near-field oblique regime, the maximum amplitude is most often associated with the propagation of edge waves. In the far field, the maximum amplitude is most often caused by the interaction of the tsunami coda that develops during basin-wide propagation and the nearshore response, including the excitation of edge waves, shelf modes, and resonance. Statistical distributions that describe tsunami observations are also reviewed, both in terms of spatial distributions, such as coseismic slip on the fault plane and near-field runup, and temporal distributions, such as wave amplitudes in the far field. In each case, fundamental theories of tsunami physics are heuristically used to explain the observations.

  17. Imaging CSEM data in the presence of electrical anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Newman, G.A.; Commer, M.; Carazzone, J.J.

    2009-09-10

    Formation anisotropy should be incorporated into the analysis of controlled source electromagnetic (CSEM) data because failure to do so can produce serious artifacts in the resulting resistivity images for certain data configurations of interest. This finding is demonstrated in model and case studies. Sensitivity to horizontal resistivity will be strongest in the broadside electric field data where detectors are offset from the tow line. Sensitivity to the vertical resistivity is strongest for over flight data where the transmitting antenna passes directly over the detecting antenna. Consequently, consistent treatment of both over flight and broadside electric field measurements requires an anisotropic modeling assumption. To produce a consistent resistivity model for such data we develop and employ a 3D CSEM imaging algorithm that treats transverse anisotropy. The algorithm is based upon non-linear conjugate gradients and full wave equation modeling. It exploits parallel computing systems to effectively treat 3D imaging problems and CSEM data volumes of industrial size. Here we use it to demonstrate the anisotropic imaging process on model and field data sets from the North Sea and offshore Brazil. We also verify that isotropic imaging of over flight data alone produces an image generally consistent with the vertical resistivity. However, superior data fits are obtained when the same over flight data are analyzed assuming an anisotropic resistivity model.

  18. Proximity fed gap-coupled half E-shaped microstrip antenna array

    Indian Academy of Sciences (India)

    Amit A Deshmukh; K P Ray

    2015-02-01

    Broadband gap-coupled array configuration of proximity fed rectangular microstrip antenna with half E-shaped microstrip antennas are proposed. The rectangular slot in half E-shaped patch reduces the orthogonal TM01 mode resonance frequency of equivalent rectangular patch and along with TM10 modes of fed and parasitic rectangular patches, yields broader bandwidth of more than 470 MHz (> 45%). An improvement in radiation pattern and gain characteristics over the bandwidth is obtained by gap-coupling half E-shaped patches along all the edges of proximity fed rectangular patch, which yields bandwidth of nearly 510 MHz (∼49%). Further to enhance the gain, a gap-coupled 3 × 3 array configuration of half E-shaped patches with proximity fed rectangular microstrip antenna is proposed. The gap-coupled array configuration yields bandwidth of more than 530 MHz (>50%) with broadside radiation pattern and peak gain of 11 dBi.

  19. A method for testing handgun bullets in deer

    CERN Document Server

    Courtney, M; Courtney, Amy; Courtney, Michael

    2007-01-01

    Using service handguns to test bullets in deer is problematic because of velocity loss with range and accuracy giving sub-optimal shot placement. An alternate method is presented using a scoped muzzleloader shooting saboted handgun bullets to allow precise (within 2" in many cases) shot placement for studying terminal ballistics in a living target. Deer are baited to a known range and path obstructions are used to place the deer broadside to the shooter. Muzzleloading powder charges provide a combination of muzzle velocity and velocity loss due to air resistance for a given ballistic coefficient that produce impact velocities corresponding to typical pistol velocities. With readily available sabots, this approach allows for testing of terminal ballistics of .355, .357, .40, .429, .45, and .458 caliber bullets with two muzzleloaders (.45 and .50 caliber). Examples are described demonstrating the usefulness of testing handgun bullets in deer for acoustic shooting event reconstruction, understanding tissue damag...

  20. Analysis and design of a composite left-/right-handed leaky wave antenna based on the H10 rectangular waveguide mode

    Directory of Open Access Journals (Sweden)

    T. F. Eibert

    2008-05-01

    Full Text Available The presented "open" composite left-handed/right-handed (CRHLH substrate integrated waveguide performs well as a low-profile leaky wave antenna. This design is distinguished due to the fact that it is derived from the approved equivalent circuit model of the H10 rectangular hollow waveguide mode. The wave propagation behaviour is visualised by the dispersion diagram calculated by two different methods, infinite periodic full-wave simulation and Matrix-Pencil analysis of driven field solutions. The periodic configuration is also analysed in terms of the Bloch impedance. Although FR-4 serves as substrate the antenna features an efficiency of about 50% to 60%. The radiation performance demonstrates nearly backfire to almost endfire scanning capability of the antenna by mere frequency variation. Broadside radiation is possible due to the balanced state at 4 GHz.

  1. Kramářská píseň

    Czech Academy of Sciences Publication Activity Database

    Traxler, Jiří

    Vol. 2. 1. Praha : Etnologický ústav AV ČR, v. v. i. v Praze a Ústav evropské etnologie Filozofické fakulty Masarykovy univerzity v Brně v nakladatelství Mladá fronta, 2007 - (Brouček, S.; Jeřábek, R.), s. 427-430 ISBN 978-80-204-1712-1 R&D Projects: GA ČR(CZ) GA404/93/1230; GA ČR(CZ) GA404/96/1416 Institutional research plan: CEZ:AV0Z9058907; CEZ:AV0Z90580513 Keywords : broadside * chapman song * murder ballad * broadsheet * chapbook Subject RIV: AC - Archeology, Anthropology, Ethnology

  2. Dual-Band Operation of a Circularly Polarized Four-Arm Curl Antenna with Asymmetric Arm Length

    Directory of Open Access Journals (Sweden)

    Son Xuat Ta

    2016-01-01

    Full Text Available This paper presents dual-band operation of a single-feed composite cavity-backed four-arm curl antenna. Dual-band operation is achieved with the presence of the asymmetrical arm structure. A pair of vacant-quarter printed rings is used in the feed structure to produce a good circular polarization (CP at both bands. The cavity-backed reflector is employed to improve the CP radiation characteristics in terms of the 3-dB axial ratio beamwidth and broadside gain. The proposed antenna is widely applicable in dual-band communication systems that have a small frequency ratio. Examples of such a system are global positioning systems.

  3. A radial line slot antenna for 12 GHz satellite TV reception

    Science.gov (United States)

    Ando, M.; Sakurai, K.; Goto, N.; Arimura, K.; Ito, Y.

    1985-12-01

    The analysis and design of novel planar antennas which can radiate circularly polarized pencil beams in X-band are presented for the application of receiving direct broadcast from a satellite (DBS). This antenna belongs to a class of slotted waveguide antennas and high efficiency is expected in principle. A circular two-dimensional aperture is located on the top plate of a twofold radial waveguide and is excited by a radially inward traveling transverse electromagnetic (TEM) mode in the upper waveguide. Slots are arrayed on the aperture spirally in such a way that they can coupled with the radial currents flowing over the aperture plate to produce a circularly polarized broadside beam. Promising performances of the antenna are predicted theoretically. Experiments are performed with respect to basic characteristics of the antenna and they show the validity of the design and analysis.

  4. Miniaturized Planar Split-Ring Resonator Antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2009-01-01

    A miniaturized planar antenna based on a broadside-coupled split ring resonator excited by an arc-shaped dipole is presented. The excitation dipole acts as a small tuning capacitor in series with a parallel RLC circuit represented by the SRR. The antenna resonance frequency and dimensions a...... essentially determined by the SRR, while by varying the dipole arm length the input resistance is changed in a wide range, thus matching the antenna to a feed line and compensating for simulation and manufacturing inaccuracies. No additional matching network is required. Theoretically, there is no limit on...... subsequently tuned to 50 ohms simply by cutting out the excessive arm length. This tuning technique is especially useful in practical applications, since it allows the antenna to be tuned in-place and thereby compensate for various inaccuracies as well as for an antenna environment....

  5. Detection and analysis of radio pulses from extensive air showers

    International Nuclear Information System (INIS)

    Radio pulses from extensive air showers(EAS) at 30, 44 and 60 MHz frequencies have been studied, using wide band broad-side arrays of half-wave dipole antenna systems. The experimental results support the theoretical prediction that the field strength of radioemission depends on the shower size. An asymmetry has been noticed in the pulse height distributions of radio pulses detected by North-South and East-West directed arrays. These observations are in agreement with the theory that the charge separation mechanism is predominant in generating radio pulses from EAS and radio emission is polarised in the East-West direction. Experimental data are compared with those of earlier workers. (author)

  6. Novel Design of Microstrip Antenna with Improved Bandwidth

    Directory of Open Access Journals (Sweden)

    Km. Kamakshi

    2014-01-01

    Full Text Available A novel design of broadband patch antenna is presented in this paper. The broadband property of the proposed antenna is achieved by choosing a proper selection of dimensions and positions of slot and notch on the radiating patch. The bandwidth of the proposed antenna is found to be 30.5% with operating frequency band from 1.56 GHz to 2.12 GHz. Antenna characteristics are observed for different inclination angles “α” and its effect on bandwidths is also reported. The maximum gain of the antenna is found to be 9.86 dBi and it achieves broadside radiation pattern in the direction of maximum radiation over the operating band. The proposed antenna structure is simulated, fabricated, and tested for obtaining the desired performance. The simulated results are verified with experimental results which are in good agreement.

  7. Thermal engineering research. [Runge-Kutta investigation of gas flow inside multilayer insulation system for rocket booster fuel tanks

    Science.gov (United States)

    Shih, C. C.

    1973-01-01

    A theoretical investigation of gas flow inside a multilayer insulation system has been made for the case of the broadside pumping process. A set of simultaneous first-order differential equations for the temperature and pressure of the gas mixture was obtained by considering the diffusion mechanism of the gas molecules through the perforations on the insulation layers. A modified Runge-Kutta method was used for numerical experiment. The numerical stability problem was investigated. It has been shown that when the relaxation time is small compared with the time period over which the gas properties change appreciably, the set of differential equations can be replaced by a set of algebraic equations for solution. Numerical examples were given, and comparisons with experimental data were made.

  8. “A most detestable crime”. Representations of Rape in the Popular Press of Early Modern England

    Directory of Open Access Journals (Sweden)

    Donatella Pallotti

    2013-03-01

    Full Text Available In early modern England the legal definition of rape underwent an important revision and gradually, from crime against property, rape became a crime against the person. While reflecting the classical, medieval and biblical assumptions, the period brought about new concerns. The purpose of this article is to explore representations of rape in a variety of popular texts of the English early modern period, by focussing attention on broadside ballads, cheap pamphlets as well as accounts of trials that took place at the Old Bailey. These texts constitute valuable sources of information about people’s attitudes and beliefs and help us construct the views of rape circulating in early modern English culture.

  9. Compact Feeding Network for Array Radiations of Spoof Surface Plasmon Polaritons

    Science.gov (United States)

    Xu, Jun Jun; Yin, Jia Yuan; Zhang, Hao Chi; Cui, Tie Jun

    2016-03-01

    We propose a splitter feeding network for array radiations of spoof surface plasmon polaritons (SPPs), which are guided by ultrathin corrugated metallic strips. Based on the coupled mode theory, SPP fields along a single waveguide in a certain frequency range can be readily coupled into two adjacent branch waveguides with the same propagation constants. We propose to load U-shaped particles anti-symmetrically at the ends of such two branch waveguides, showing a high integration degree of the feeding network. By controlling linear phase modulations produced by the U-shaped particle chain, we demonstrate theoretically and experimentally that the SPP fields based on bound modes can be efficiently radiated to far fields in broadside direction. The proposed method shows that the symmetry of electromagnetic field modes can be exploited to the SPP transmission network, providing potential solutions to compact power dividers and combiners for microwave and optical devices and systems.

  10. Low profile conformal antenna arrays on high impedance substrate

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents electromagnetic (EM) design and analysis of dipole antenna array over high impedance substrate (HIS). HIS is a preferred substrate for low-profile antenna design, owing to its unique boundary conditions. Such substrates permit radiating elements to be printed on them without any disturbance in the radiation characteristics. Moreover HIS provides improved impedance matching, enhanced bandwidth, and increased broadside directivity owing to total reflection from the reactive surface and high input impedance. This book considers different configurations of HIS for array design on planar and non-planar high-impedance surfaces. Results are presented for cylindrical dipole, printed dipole, and folded dipole over single- and double-layered square-patch-based HIS and dogbone-based HIS. The performance of antenna arrays is analyzed in terms of performance parameters such as return loss and radiation pattern. The design presented shows acceptable return loss and mainlobe gain of radiation pattern. Thi...

  11. Micromachined On-Chip Dielectric Resonator Antenna Operating at 60 GHz

    KAUST Repository

    Sallam, Mai

    2015-06-01

    This paper presents a novel cylindrical Dielectric Resonator Antenna (DRA) suitable for millimeter-wave on-chip systems. The antenna was fabricated from a single high resistivity silicon wafer via micromachining technology. The new antenna was characterized using HFSS and experimentally with good agreement been found between the simulations and experiment. The proposed DRA has good radiation characteristics, where its gain and radiation efficiency are 7 dBi and 79.35%, respectively. These properties are reasonably constant over the working frequency bandwidth of the antenna. The return loss bandwidth was 2.23 GHz, which corresponds to 3.78% around 60 GHz. The antenna was primarily a broadside radiator with -15 dB cross polarization level.

  12. A Two Element Plasma Antenna Array

    Directory of Open Access Journals (Sweden)

    F. Sadeghikia

    2013-10-01

    Full Text Available This theoretical study presents the characteristics of plasma monopole antennas in the VHF/UHF range using finite difference time domain (FDTD simulation. Results show that more broadband characteristics can be obtained by increasing the diameter of the plasma tube and that the minor lobes diminish in intensity as diameter increases. Furthermore, the nulls are replaced by low level radiation. Since the collision frequency, which is a function of gas pressure, represents the loss mechanism of plasma, decreasing its value increases the gain and radar cross section (RCS of the antenna. Theoretical modeling shows that at higher plasma frequencies with respect to the signal frequency, the gain and radar cross section of the plasma antenna are high enough and that the impedance curves are altered as the plasma frequency varies. Using these preliminary studies, mutual impedance and gain of a broadside array of two parallel side-by-side plasma elements is presented.

  13. Corporate array of micromachined dipoles on silicon wafer for 60 GHz communication systems

    KAUST Repository

    Sallam, M. O.

    2013-03-01

    In this paper, an antenna array operating at 60 GHz and realized on 0.675 mm thick silicon substrate is presented. The array is constructed using four micromachined half-wavelength dipoles fed by a corporate feeding network. Isolation between the antenna array and its feeding network is achieved via a ground plane. This arrangement leads to maximizing the broadside radiation with relatively high front-to-back ratio. Simulations have been carried out using both HFSS and CST, which showed very good agreement. Results reveal that the proposed antenna array has good radiation characteristics, where the directivity, gain, and radiation efficiency are around 10.5 dBi, 9.5 dBi, and 79%, respectively. © 2013 IEEE.

  14. A Simplified Theory of Coupled Oscillator Array Phase Control

    Science.gov (United States)

    Pogorzelski, R. J.; York, R. A.

    1997-01-01

    Linear and planar arrays of coupled oscillators have been proposed as means of achieving high power rf sources through coherent spatial power combining. In such - applications, a uniform phase distribution over the aperture is desired. However, it has been shown that by detuning some of the oscillators away from the oscillation frequency of the ensemble of oscillators, one may achieve other useful aperture phase distributions. Notable among these are linear phase distributions resulting in steering of the output rf beam away from the broadside direction. The theory describing the operation of such arrays of coupled oscillators is quite complicated since the phenomena involved are inherently nonlinear. This has made it difficult to develop an intuitive understanding of the impact of oscillator tuning on phase control and has thus impeded practical application. In this work a simpl!fied theory is developed which facilitates intuitive understanding by establishing an analog of the phase control problem in terms of electrostatics.

  15. Isotropic Single Negative Metamaterials

    Directory of Open Access Journals (Sweden)

    P. Protiva

    2008-09-01

    Full Text Available This paper presents the application of simple, and therefore cheap, planar resonators for building 3D isotropic metamaterials. These resonators are: a broadside-coupled split ring resonator with a magnetic response providing negative permeability; an electric dipole terminated by a loop inductor together with a double H-shaped resonator with an electric response providing negative permittivity. Two kinds of 3D isotropic single negative metamaterials are reported. The first material consists of unit cells in the form of a cube bearing on its faces six equal planar resonators with tetrahedral symmetry. In the second material, the planar resonators boxed into spherical plastic shells and randomly distributed in a hosting material compose a real 3D volumetric metamaterial with an isotropic response. In both cases the metamaterial shows negative permittivity or permeability, according to the type of resonators that are used. The experiments prove the isotropic behavior of the cells and of the metamaterial specimens.

  16. Target Strength of Southern Resident Killer Whales (Orcinus orca): Measurement and Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jinshan; Deng, Zhiqun; Carlson, Thomas J.; Moore, Brian

    2012-04-04

    A major criterion for tidal power licensing in Washington’s Puget Sound is the management of the risk of injury to killer whales due to collision with moving turbine blades. An active monitoring system is being proposed for killer whale detection, tracking, and alerting that links to and triggers temporary turbine shutdown when there is risk of collision. Target strength (TS) modeling of the killer whale is critical to the design and application of any active monitoring system. A 1996 study performed a high-resolution measurement of acoustic reflectivity as a function of frequency of a female bottlenose dolphin (2.2 m length) at broadside aspect and TS as a function of incident angle at 67 kHz frequency. Assuming that killer whales share similar morphology structure with the bottlenose dolphin, we extrapolated the TS of an adult killer whale 7.5 m in length at 67 kHz frequency with -8 dB at broadside aspect and -28 dB at tail side. The backscattering data from three Southern Resident killer whales were analyzed to obtain the TS measurement. These data were collected at Lime Kiln State Park using a split-beam system deployed from a boat. The TS of the killer whale at higher frequency (200 kHz) was estimated based on a three-layer model for plane wave reflection from the lung of the whale. The TS data of killer whales were in good agreement with our model. In this paper, we also discuss and explain possible causes for measurement estimation error.

  17. Twist viscosities and flow alignment of biaxial nematic liquid crystal phases of a soft ellipsoid-string fluid studied by molecular dynamics simulation.

    Science.gov (United States)

    Sarman, Sten; Laaksonen, Aatto

    2012-09-14

    We have calculated the twist viscosity and the alignment angle between the director and the stream lines in shear flow of a liquid crystal model system, which forms biaxial nematic liquid crystals, as functions of the density, from the Green-Kubo relations by equilibrium molecular dynamics simulation and by a nonequilibrium molecular dynamics algorithm, where a torque conjugate to the director angular velocity is applied to rotate the director. The model system consists of a soft ellipsoid-string fluid where the ellipsoids interact according a repulsive version of the Gay-Berne potential. Four different length-to-width-to-breadth ratios have been studied. On compression, this system forms discotic or calamitic uniaxial nematic phases depending on the dimensions of the molecules, and on further compression a biaxial nematic phase is formed. In the uniaxial nematic phase there is one twist viscosity and one alignment angle. In the biaxial nematic phase there are three twist viscosities and three alignment angles corresponding to the rotation around the various directors and the different alignments of the directors relative to the stream lines, respectively. It is found that the smallest twist viscosity arises by rotation around the director formed by the long axes, the second smallest one arises by rotation around the director formed by the normals of the broadsides, and the largest one by rotation around the remaining director. The first twist viscosity is rather independent of the density whereas the last two ones increase strongly with density. One finds that there is one stable director alignment relative to the streamlines, namely where the director formed by the long axes is almost parallel to the stream lines and where the director formed by the normals of the broadsides is almost parallel to the shear plane. The relative magnitudes of the components of the twist viscosities span a fairly wide interval so this model should be useful for parameterisation

  18. Understanding and optimizing microstrip patch antenna cross polarization radiation on element level for demanding phased array antennas in weather radar applications

    Science.gov (United States)

    Vollbracht, D.

    2015-11-01

    The antenna cross polarization suppression (CPS) is of significant importance for the accurate calculation of polarimetric weather radar moments. State-of-the-art reflector antennas fulfill these requirements, but phased array antennas are changing their CPS during the main beam shift, off-broadside direction. Since the cross polarization (x-pol) of the array pattern is affected by the x-pol element factor, the single antenna element should be designed for maximum CPS, not only at broadside, but also for the complete angular electronic scan (e-scan) range of the phased array antenna main beam positions. Different methods for reducing the x-pol radiation from microstrip patch antenna elements, available from literature sources, are discussed and summarized. The potential x-pol sources from probe fed microstrip patch antennas are investigated. Due to the lack of literature references, circular and square shaped X-Band radiators are compared in their x-pol performance and the microstrip patch antenna size variation was analyzed for improved x-pol pattern. Furthermore, the most promising technique for the reduction of x-pol radiation, namely "differential feeding with two RF signals 180° out of phase", is compared to single fed patch antennas and thoroughly investigated for phased array applications with simulation results from CST MICROWAVE STUDIO (CST MWS). A new explanation for the excellent port isolation of dual linear polarized and differential fed patch antennas is given graphically. The antenna radiation pattern from single fed and differential fed microstrip patch antennas are analyzed and the shapes of the x-pol patterns are discussed with the well-known cavity model. Moreover, two new visual based electromagnetic approaches for the explanation of the x-pol generation will be given: the field line approach and the surface current distribution approach provide new insight in understanding the generation of x-pol component in microstrip patch antenna radiation

  19. Space-Variant Post-Filtering for Wavefront Curvature Correction in Polar-Formatted Spotlight-Mode SAR Imagery

    Energy Technology Data Exchange (ETDEWEB)

    DOREN,NEALL E.

    1999-10-01

    Wavefront curvature defocus effects occur in spotlight-mode SAR imagery when reconstructed via the well-known polar-formatting algorithm (PFA) under certain imaging scenarios. These include imaging at close range, using a very low radar center frequency, utilizing high resolution, and/or imaging very large scenes. Wavefront curvature effects arise from the unrealistic assumption of strictly planar wavefronts illuminating the imaged scene. This dissertation presents a method for the correction of wavefront curvature defocus effects under these scenarios, concentrating on the generalized: squint-mode imaging scenario and its computational aspects. This correction is accomplished through an efficient one-dimensional, image domain filter applied as a post-processing step to PF.4. This post-filter, referred to as SVPF, is precalculated from a theoretical derivation of the wavefront curvature effect and varies as a function of scene location. Prior to SVPF, severe restrictions were placed on the imaged scene size in order to avoid defocus effects under these scenarios when using PFA. The SVPF algorithm eliminates the need for scene size restrictions when wavefront curvature effects are present, correcting for wavefront curvature in broadside as well as squinted collection modes while imposing little additional computational penalty for squinted images. This dissertation covers the theoretical development, implementation and analysis of the generalized, squint-mode SVPF algorithm (of which broadside-mode is a special case) and provides examples of its capabilities and limitations as well as offering guidelines for maximizing its computational efficiency. Tradeoffs between the PFA/SVPF combination and other spotlight-mode SAR image formation techniques are discussed with regard to computational burden, image quality, and imaging geometry constraints. It is demonstrated that other methods fail to exhibit a clear computational advantage over polar-formatting in conjunction

  20. Unified physical mechanism of frequency-domain controlled-source electromagnetic exploration on land and in ocean

    Science.gov (United States)

    Liu, Changsheng; Lin, Jun; Zhou, Fengdao; Hu, Ruihua; Sun, Caitang

    2013-12-01

    The frequency-domain controlled-source electromagnetic method (FDCSEM) has played an important role in the terrestrial and oceanic exploration. However, the measuring manners and the detecting abilities in two kinds of environment are much different. This paper analyses the electromagnetic theories of the FDCSEM exploration on land and in ocean, simulates the electromagnetic responses in the two cases based on a united physical and mathematical model, and studies the physical mechanism leading to these differences. In this study, the relationship between the propagation paths and the detecting ability is illuminated and the way to improve the detecting ability of FDCSEM is brought forward. In terrestrial exploration, FDCSEM widely adopts the measuring manner of controlled-source audio-frequency magnetotelluric method (CSAMT), which records the electromagnetic fields in the far zone in the broadside direction of an electric dipole source. This manner utilizes the airwave (i.e. the Earth surface wave) and takes the stratum wave as interference. It is sensitive to the conductive target but insensitive to the resistive one. In oceanic exploration, FDCSEM usually adopts the measuring manner of marine controlled-source electromagnetic method (MCSEM), which records the electromagnetic fields, commonly the horizontal electric fields, in the in-line direction of the electric dipole source. This manner utilizes the stratum wave (i.e. the seafloor wave and the guided wave in resistive targets) and takes the airwave as interference. It is sensitive to the resistive target but relatively insensitive to the conductive one. The numerical simulation shows that both the airwave and the stratum wave contribute to the FDCSEM exploration. United utilization of them will enhance the anomalies of targets and congregate the advantages of CSAMT and MCSEM theories. At different azimuth and different offset, the contribution of the airwave and the stratum wave to electromagnetic anomaly is

  1. 大型浮式结构物结构碰撞性能分析%On collision performance of large lfoating structures

    Institute of Scientific and Technical Information of China (English)

    张延昌; 刘昆; 王璞; 景宝金

    2015-01-01

    The collision accident is of great attention during the design under accidental limit state with increasing importance. A large lfoating structure is taken as the research object in this paper. Firstly, the collision scenarios described by rules of ISO, API, HSE, DNV, ABS, BV and LR are summarized and analyzed, resulting in the analysis and design criteria of the collision scenarios. The collision mechanics model is developed based on the simpliifed analysis method. The numerical simulation and analysis are carried out by the nonlinear dynamic structural analysis software ABAQUS. The crashworthiness of broadside structure is checked and evaluated through the analysis of plastic strain, plastic deformation, energy absorption, impact force and movement. And the effects of different collision positions and the striking ship type on collision performance has also been analyzed. The results show that the collision accidental limit strength of broadside collision can meet the rule requirements, and the stem collision which is relatively dangerous can be selected as an analytical control condition.%碰撞事故是基于事故极限状态设计重点考虑的对象,在设计中越来越受到重视。文章以某大型浮式结构物为研究对象,总结分析ISO、API、HSE、DNV、ABS、BV、LR等标准及规范对碰撞场景的相关规定,提出碰撞分析场景及设计衡准;基于简化分析技术建立碰撞力学模型,利用动态非线性结构分析软件ABAQUS进行仿真分析,通过分析塑性应变、塑性变形、吸能、碰撞力及运动等,校核评估舷侧结构的耐撞性能;分析不同碰撞位置、撞击船型式等对碰撞性能的影响。研究表明:目标大型浮式结构物舷侧结构碰撞事故极限强度满足规范要求,首柱撞击相对比较危险,可作为计算分析控制工况。

  2. Optimal spatial filtering for design of a conformal velocity sonar array

    Science.gov (United States)

    Traweek, Charles M.

    In stark contrast to the ubiquitous optimization problem posed in the array processing literature, tactical hull sonar arrays have traditionally been designed using extrapolations of low spatial resolution empirical self noise data, dominated by hull noise at moderate speeds, in conjunction with assumptions regarding achievable conventional beamformer sidelobe levels by so-called Taylor shading for a time domain, delay-and-sum beamformer. That ad hoc process defaults to an extremely conservative (expensive and heavy) design for an array baffle as a means to assure environmental noise limited sonar performance. As an alternative, this dissertation formulates, implements, and demonstrates an objective function that results from the expression of the log likelihood ratio of the optimal Bayesian detector as a comparison to a threshold. Its purpose is to maximize the deflection coefficient of a square-law energy detector over an arbitrarily specified frequency band by appropriate selection of array shading weights for the generalized conformal velocity sonar array under the assumption that it will employ the traditional time domain delay-and-sum beamformer. The restrictive assumptions that must be met in order to appropriately use the deflection coefficient as a performance metric are carefully delineated. A series of conformal velocity sonar array spatial filter optimization problems was defined using a data set characterized by spatially complex structural noise from a large aperture conformal velocity sonar array experiment. The detection performance of an 80-element cylindrical array was optimized over a reasonably broad range of frequencies (from k0a = 12.95 to k 0a = 15.56) for the cases of broadside and off-broadside signal incidence. In each case, performance of the array using optimal real-valued time domain delay-and-sum beamformer weights was much better than that achieved for either uniform shading or for Taylor shading. The result is an analytical engine

  3. Massively-parallel electrical-conductivity imaging of hydrocarbonsusing the Blue Gene/L supercomputer

    Energy Technology Data Exchange (ETDEWEB)

    Commer, M.; Newman, G.A.; Carazzone, J.J.; Dickens, T.A.; Green,K.E.; Wahrmund, L.A.; Willen, D.E.; Shiu, J.

    2007-05-16

    Large-scale controlled source electromagnetic (CSEM)three-dimensional (3D) geophysical imaging is now receiving considerableattention for electrical conductivity mapping of potential offshore oiland gas reservoirs. To cope with the typically large computationalrequirements of the 3D CSEM imaging problem, our strategies exploitcomputational parallelism and optimized finite-difference meshing. Wereport on an imaging experiment, utilizing 32,768 tasks/processors on theIBM Watson Research Blue Gene/L (BG/L) supercomputer. Over a 24-hourperiod, we were able to image a large scale marine CSEM field data setthat previously required over four months of computing time ondistributed clusters utilizing 1024 tasks on an Infiniband fabric. Thetotal initial data misfit could be decreased by 67 percent within 72completed inversion iterations, indicating an electrically resistiveregion in the southern survey area below a depth of 1500 m below theseafloor. The major part of the residual misfit stems from transmitterparallel receiver components that have an offset from the transmittersail line (broadside configuration). Modeling confirms that improvedbroadside data fits can be achieved by considering anisotropic electricalconductivities. While delivering a satisfactory gross scale image for thedepths of interest, the experiment provides important evidence for thenecessity of discriminating between horizontal and verticalconductivities for maximally consistent 3D CSEM inversions.

  4. Radar Imaging of Spheres in 3D using MUSIC

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D H; Berryman, J G

    2003-01-21

    We have shown that multiple spheres can be imaged by linear and planar EM arrays using only one component of polarization. The imaging approach involves calculating the SVD of the scattering response matrix, selecting a subset of singular values that represents noise, and evaluating the MUSIC functional. The noise threshold applied to the spectrum of singular values for optimal performance is typically around 1%. The resulting signal subspace includes more than one singular value per sphere. The presence of reflections from the ground improves height localization, even for a linear array parallel to the ground. However, the interference between direct and reflected energy modulates the field, creating periodic nulls that can obscure targets in typical images. These nulls are largely eliminated by normalizing the MUSIC functional with the broadside beam pattern of the array. The resulting images show excellent localization for 1 and 2 spheres. The performance for the 3 sphere configurations are complicated by shadowing effects and the greater range of the 3rd sphere in case 2. Two of the three spheres are easily located by MUSIC but the third is difficult to distinguish from other local maxima of the complex imaging functional. Improvement is seen when the linear array is replace with a planar array, which increases the effective aperture height. Further analysis of the singular values and their relationship to modes of scattering from the spheres, as well as better ways to exploit polarization, should improve performance. Work along these lines is currently being pursued by the authors.

  5. Dynamics of two disks settling in a two-dimensional narrow channel: From periodic motion to vertical chain in Oldroyd-B fluid

    CERN Document Server

    Pan, Tsorng-Whay

    2016-01-01

    In this article we present a numerical study of the dynamics of two disks settling in a narrow vertical channel filled with Oldroyd-B fluid. Two kinds of particle dynamics are obtained: (i) periodic interaction between two disks and (ii) the chain formation of two disks. For the periodic interaction of two disks, two different motions are obtained: (a) two disks stay far apart and interact periodically and (b) two disks interact closely and then far apart in a periodic way, like the drafting, kissing and tumbling of two disks sedimenting in Newtonian fluid, due to the lack of strong enough elastic force. For the formation of two disk chain occurred at higher values of the elasticity number, it is either a tilted chain or a vertical chain. The tilted chain can be obtained for either that the elasticity number is less than the critical value for having the vertical chain or that the Mach number is greater than the critical value for a long body to fall broadside-on. Hence the values of the elasticity number and...

  6. Ultra-wideband radar target detection for sloped and diffuse scattering environments

    Science.gov (United States)

    Mitra, Atindra K.; Lewis, Thomas L.; LaRue, James P.; Shaw, Arnab K.

    2004-09-01

    This paper extends simulation and target detection results from an investigation entitled "Self-Training Algorithms for Ultra-wideband SAR Target Detection" that was conducted last year and presented at the 2003 SPIE Aerosense Conference on "Algorithms for Synthetic Aperture Radar Imagery." Under this approach, simulated SAR impulse clutter data was generated by modulating a tophat model for the SAR video phase history with K-distributed data models. Targets were synthesized and "instanced" within the SAR image via the application of a dihedral model to represent broadside targets. For this paper, these models are extended and generalized by developing a set of models that approximate major scattering mechanisms due to terrain relief and approximate major scattering mechanisms due to scattering from off-angle targets. Off-angle targets are difficult to detect at typical ultra-wideband radar frequencies and are denoted as "diffuse scatterers." Potential approaches for detecting synthetic off-angle targets that demonstrate this type of "diffuse scattering" are developed and described in the algorithms and results section of the paper. A preliminary set of analysis outputs are presented with synthetic data from the resulting simulation testbed.

  7. New Polarization Basis for Polarimetric Phased Array Weather Radar: Theory and Polarimetric Variables Measurement

    Directory of Open Access Journals (Sweden)

    Jian Dong

    2012-01-01

    Full Text Available A novel scheme is developed for mitigating measurement biases in agile-beam polarimetric phased array weather radar. Based on the orthogonal Huygens source dual-polarized element model, a polarization measurement basis for planar polarimetric phased array radar (PPAR is proposed. The proposed polarization basis is orthogonal to itself after a 90° rotation along the array’s broadside and can well measure the characteristics of dual-polarized element. With polarimetric measurements being undertaken in this polarization basis, the measurement biases caused by the unsymmetrical projections of dual-polarized element’s fields onto the local horizontal and vertical directions of radiated beam can be mitigated. Polarimetric variables for precipitation estimation and classification are derived from the scattering covariance matrix in horizontal and vertical polarization basis. In addition, the estimates of these parameters based on the time series data acquired with the new polarization basis are also investigated. Finally, autocorrelation methods for both the alternate transmission and simultaneous reception mode and the simultaneous transmission and simultaneous reception mode are developed.

  8. Evaporation of uniform antireflection coatings on hemispherical lenses to enhance infrared antenna gain

    Science.gov (United States)

    Slovick, Brian A.; Krenz, Peter M.; Zummo, Guy; Boreman, Glenn D.

    2010-03-01

    Infrared dipole-coupled bolometers receive radiation more efficiently when illuminated through a high permittivity, antireflection (AR) coated, hemispherical immersion lens. To maintain the enhanced responsivity for all illumination angles, the AR coating must be uniform over the hemispherical surface. An evaporation method for depositing a uniform AR coating on the hemispherical surface is presented. The lens is tilted relative to the source, which can be either electron-beam or thermal, and rotated throughout the deposition. Evaporation at an angle of 70° yields a uniform film with less than 10% thickness variation over a 120° full angle of the hemispherical surface. A theoretical model is developed and compared to profilometer measurements. In all cases, there is general agreement between theory and measurement. A single dipole is fabricated onto the flat surface of an AR-coated germanium immersion lens and the responsivity is measured for both substrate-side and air-side illumination. With a zinc sulfide (ZnS) single-layer AR coating, substrate-side illumination yields a broadside antenna response 49 ± 2.7 times greater than air-side illumination.

  9. Aircraft-skin Infrared Radiation Characteristics Modeling and Analysis

    Institute of Scientific and Technical Information of China (English)

    Lu Jianwei; Wang Qiang

    2009-01-01

    One of the most important problems of stealth technology is to evaluate the infrared radiation (IR) level received by IR sensors from fighters to be detected. This article presents a synthetic method for calculating the IR emitted from aircraft-skin. By reckoning the aerodynamic heating and hot engine casing to be the main heat sources of the exposed aircraft-skin, a numerical model of skin temperature distribution is established through computational fluid dynamics (CFD) technique. Based on it, an infrared signature model for solving the complex geometry and structure of a fighter is proposed with the reverse Monte Carlo (RMC) method. Finally, by way of determining the IR intensity from aircraft-skin, the aircraft components that emit the most IR can be identified; and the cooling effects of the main aircraft components on IR intensity are investigated. It is found that reduction by 10 K in the skin temperature of head, vertical stabilizers and wings could lead to decline of more than 8% of the IR intensity on the aircraft-skin in front view while at the broadside of the aircraft, the drops in IR intensity could attain under 8%. The results provide useful reference in designing stealthy aircraft.

  10. Parametric Study of Cylindrical Dielectric Resonator Antenna (CDRA Feeder with Symmetric Parabolic Reflector

    Directory of Open Access Journals (Sweden)

    S.M. Ali

    2015-06-01

    Full Text Available In this study a parabolic reflector antenna is designed and fabricated for IEEE 802.11a WLAN application. Initially, a single element circular tuning slot coupled Cylindrical Dielectric Resonator Antenna (CDRA feeder is designed and fabricated for a symmetric parabolic reflector. Subsequently, the designed feeder is integrated at the focal point of the parabolic reflector to provide unidirectional radiation pattern with improved gain and sidelobe levels. The measured fractional impedance bandwidth achieved for the proposed antenna is 1.8% for S11<-10 dB from 5.32 to 5.52 GHz. A radiation pattern with broadside radiation and low back radiation has been obtained. A good measurement gain of approximately 13 dB is achieved over the bandwidth by placing CDRA feeder at the focal point of the parabolic reflector. In addition, a comprehensive parametric study has been conducted to realize the effect of slot size and position on the resonance frequency of the designed feeder. Furthermore, a parametric study of various reflector parameters has also been performed to study the effect of size, depth and focal point of the parabolic reflector on gain of the antenna. Important design factors have been identified from the parametric study of the antenna. The experimental and measured results show that the designed antenna is suitable for IEEE WLAN 802.11a wireless application.

  11. Circularly Polarized Microstrip Yagi Array Antenna with Wide Beamwidth and High Front-to-Back Ratio

    Directory of Open Access Journals (Sweden)

    Yun Hao

    2016-01-01

    Full Text Available A circularly polarized (CP Microstrip Yagi array antenna (MSYA is designed in order to achieve high front-to-back ratio R(F/B and high gain over wide range in the forward radiation space. A Wilkinson power divider owning two output ways with the same magnitude and different phase is used to feed the antenna. Parametric studies are carried out to investigate the effects of some key geometrical sizes on the antenna’s performance. A prototype of the antenna is fabricated, and good agreement between the measured results and the numerical simulations is observed. The overlap bandwidth of VSWR ≤ 1.5 and AR ≤ 3 dB is about 11%. The steering angle (α between the peak gain direction and the broadside can achieve 35°, R(F/B reaches 19 dB, and the gain at the front point (G0 is only 4.3 dB lower than the maximum gain (Gm. The antenna has a wide beamwidth CP radiation pattern over wide spatial range including 0° ≤ θ ≤ 90° in vertical plane and −35° ≤ φ ≤ 55° in horizontal plane.

  12. High-Gain Textile Antenna Array System for Off-Body Communication

    Directory of Open Access Journals (Sweden)

    Maria Lucia Scarpello

    2012-01-01

    Full Text Available A novel high-gain textile antenna array system, fully integrated into a rescue-worker’s vest and operating in the Industrial, Scientific, and Medical wireless band (2.4–2.4835 GHz, is presented. The system comprises an array consisting of four tip-truncated equilateral triangular microstrip patch antennas (ETMPAs, a power divider, line stretchers, and coaxial cables. The array is vertically positioned on the human torso to produce a narrow beam in elevation, as such reducing fading and allowing to steer the maximum gain in a small angular sector centered around the broadside direction. To allow simple low-cost beam steering, we specifically minimize mutual coupling by using a relative large distance between the patches and by selecting the ETMPA element as the most suited topology from three potential patch geometries. Moreover, we investigate the stability of return loss and mutual coupling characteristics under different relative humidity conditions, when bending the array, when placing the system on-body, and when covering it by different textile layers. Reflection coefficient and gain patterns are simulated and measured for the antenna system in free space and placed on the human body.

  13. Development, manufacture and testing of a planar-array L-band antenna

    Science.gov (United States)

    Frisch, E.; Siegling, H. F.; Fasold, D.

    1981-02-01

    A circularly polarised 1.5 GHz antenna was built and tested for use as an earth coverage antenna for use on board geostationary satellites. A rigid foam panel of extremely low dielectric loss coated with aluminium on the surfaces to give a sandwich effect forms the interior of a TE sub 50 resonator. The slot pattern is etched on one broadside of the skin. During development, sandwich and frame construction methods were evaluated, a structural analysis using NASTRAN performed, and tests for tests for dielectric losses of foams made. Foams were also tested for density variations, tensile strength, and outgassing. Thermal control considerations are given. The rear of the antenna is covered with superinsulation. Far field measurement tests show maximum gain 19.4 dB; gain at edge of earth 15.2 dB; ellipticity at edge of earth 2.5 dB and fundamental resonance 140 Hz. The reduction in gain due to the foam is less than 0.1 dB.

  14. Hydrogen sensing with Pd-coated long-range surface plasmon membrane waveguides.

    Science.gov (United States)

    Fong, Norman R; Berini, Pierre; Tait, R N

    2016-02-21

    A low power, reusable optical hydrogen sensor using long-range surface plasmon polariton (LRSPP) cladded membrane waveguides is demonstrated. The sensor incorporates a 5 μm wide, 20 nm thick gold stripe embedded in a 160 nm thick free-standing Cytop membrane with a 5 nm thick Pd over-layer. Input and output coupling is achieved with directly integrated broadside grating couplers. The sensor is tested with hydrogen concentrations up to 3% and demonstrates a strong response with an estimated detection limit of 290 ppm, and a response time of 7 s to a 0.6% H2 step - this level of performance is among the best reported for optical H2 sensors. Cycling of the hydrogen exposure shows a significant hysteresis response, however no film deformation or delamination was observed over many cycles. The high stress that is induced in clamped films during hydrogenation is relaxed in due to the film being deposited on the flexible and elastic Cytop membrane. This could result in improved lifetimes for this sensor and increased uptake ability. PMID:26838667

  15. The Disappearing Solar Filament of 2003 June 11: A Three-body Problem

    Science.gov (United States)

    Balasubramaniam, K. S.; Pevtsov, A. A.; Cliver, E. W.; Martin, S. F.; Panasenco, O.

    2011-12-01

    The eruption of a large quiescent filament on 2003 June 11 was preceded by the birth of a nearby active region—a common scenario. In this case, however, the filament lay near a pre-existing active region and the new active region did not destabilize the filament by direct magnetic connection. Instead it appears to have done so indirectly via magnetic coupling with the established region. Restructuring between the perturbed fields of the old region and the filament then weakened the arcade overlying the midpoint of filament, where the eruption originated. The inferred rate (~11° day-1) at which the magnetic disturbance propagates from the mature region to destabilize the filament is larger than the mean speed (~5º-6° day-1) but still within the scatter obtained for Bruzek's empirical relationship between the distance from a newly formed active region to a quiescent filament and the time from active region appearance to filament disappearance. The higher propagation speed in the 2003 June 11 case may be due to the "broadside" (versus ''end-on") angle of attack of the (effective) new flux to the coronal magnetic fields overlying a central section of the axis of the filament.

  16. Un testimonio temprano de la lira popular chilena: «Dos poetas de poncho» de Zorobabel Rodríguez

    Directory of Open Access Journals (Sweden)

    Cornejo C., Tomás

    2013-12-01

    Full Text Available In 1873 the journalist, academic and Chilean writer Zorobabel Rodríguez published an article about a striking and novel cultural event in the country: the broadside poetry. His text provides substantial information on the distribution of these, the most common themes of the poems, their preferred public and the creative process of the poets, particularly the famous Bernardino Guajardo. In addition, the position taken by Rodriguez highlights the distance between the nineteenth-century men of letters and the culture of the urban poor.En 1873 el periodista, académico y escritor chileno Zorobabel Rodríguez publicó un artículo acerca de una manifestación cultural llamativa y novedosa en el país: los pliegos sueltos de poesía. Su texto aporta cuantiosa información sobre la distribución de estos, los temas más comunes de las poesías, su público preferente y el proceso creativo de los poetas, particularmente el célebre Bernardino Guajardo. Además, la posición adoptada por Rodríguez resalta la distancia entre el mundo letrado decimonónico y las formas culturales de los sectores populares urbanos.

  17. Traffic accidents with motorcycles and their relationship to mortality.

    Science.gov (United States)

    de Oliveira, Nelson Luiz Batista; de Sousa, Regina Marcia Cardoso

    2011-01-01

    This study characterizes traffic accidents involving motorcycles according to local conditions, data concerning the type of accident, date and time, and identifies among these variables those associated with the death of victims. This retrospective study uses data from traffic collision reports from 2004 and death records from the institute of forensic medicine. A total of 99.4% of the events occurred in urban areas, where illumination (87.4%), weather conditions (80.6%); and traffic signs (70.6%) were satisfactory. Collisions between motorcycles and cars or pickup trucks prevailed (55.5%), followed by motorcycle falls (18.0%). In relation to the type of collision, the highest percentage was observed in broadside collision category (35.2%). There were differences between the groups of fatalities and survivors in relation to the area and illumination in the collision's site, in addition to the types of collision and impact. The conclusion is that local conditions and types of collision and impact stand out among the multiple variables defining the severity of accidents involving motorcycles. PMID:21584389

  18. Broadband frequency and angular response of a sinusoidal bull’s eye antenna

    Science.gov (United States)

    Beaskoetxea, U.; Navarro-Cía, M.; Beruete, M.

    2016-07-01

    A thorough experimental study of the frequency and beaming angle response of a metallic leaky-wave bull’s eye antenna working at 77 GHz with a sinusoidally corrugated profile is presented. The beam scanning property of these antennas as frequency is varied is experimentally demonstrated and corroborated through theoretical and numerical results. From the experimental results the dispersion diagram of the n  =  ‑1 and n  =  ‑2 space harmonics is extracted, and the operation at different frequency regimes is identified and discussed. In order to show the contribution of each half of the antenna, numerical examples of the near-field behavior are also displayed. Overall, experimental results are in good qualitative and quantitative agreement with theoretical and numerical calculations. Finally, an analysis of the beamwidth as a function of frequency is performed, showing that it can achieve values below 1.5° in a fractional bandwidth of 4% around the operation frequency, which is an interesting frequency-stable broadside radiation.

  19. Analysis of PBG Structures and Its Application in Cylindrical Conformal Microstrip Antenna%PBG结构分析及其在柱面共形微带天线中的应用

    Institute of Scientific and Technical Information of China (English)

    王淑娟

    2011-01-01

    利用光学Bragg反射条件,设计了两种曲面光子带隙结构,并将其应用于柱面共形微带贴片天线中,分析了光子带隙结构的结构参数对微带贴片天线性能的影响.计算仿真表明,利用合适的PBG结构可以增强微带贴片天线的前向增益,抑制高次谐波,减小旁瓣,减小表面波损耗.%According to the reflection condition of optics Bragg, the two-dimensional curved PBG structures are designed and applied to the cylindrical conformal microstrip antenna, and the parameter of PBG structures influenced on the performance of microstrip patch antenna is analyzed. The simulation results indicate that using the appropriate PBG structures can get higher gain, suppress higher harmonics, reduce broadside radiation and surface wave dissipation of the microstrip patch antenna.

  20. Pencil-Beam Single-point-fed Dirac Leaky-Wave Antenna on a Transmission-Line Grid

    CERN Document Server

    Dorrah, Ayman H

    2016-01-01

    Leaky-wave antennas (LWAs) are widely used as single-point-fed linear antenna arrays. The extension of LWAs to 2D implies that they can be used as single-point-fed 2D antenna arrays without requiring a complex feeding network. However, generating a pencil beam from 2D LWAs is not straightforward and due care has to be taken for the design of the LWA. On the other hand, transmission-line (TL) grids have demonstrated interesting behaviors, such as an effective negative refractive index and growing of evanescent waves. In this paper, a singlepoint-fed TL-grid 2D Dirac leaky-wave antenna (DLWA) design is proposed that generates a pencil beam at both broadside and slightly tilted angles. The TL-grid unit cell is analytically treated in light of its scattering and impedance matrices. The optimized TL-grid unit cell is shown to exhibit a closed bandgap in the dispersion relation which is also linearly varying with frequency (hence it is a DLWA). The proposed 2D DLWA design is fabricated and the experimental results ...

  1. A High Resolution, Light-Weight, Synthetic Aperture Radar for UAV Application

    International Nuclear Information System (INIS)

    (U) Sandia National Laboratories in collaboration with General Atomics (GA) has designed and built a high resolution, light-weight, Ku-band Synthetic Aperture Radar (SAR) known as ''Lynx''. Although Lynx can be operated on a wide variety of manned and unmanned platforms, its design is optimized for use on medium altitude Unmanned Aerial Vehicles (UAVS). In particular, it can be operated on the Predator, I-GNAT, and Prowler II platforms manufactured by GA. (U) The radar production weight is less than 120 lb and operates within a 3 GHz band from 15.2 GHz to 18.2 GHz with a peak output power of 320 W. Operating range is resolution and mode dependent but can exceed 45 km in adverse weather (4 mm/hr rain). Lynx has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in strip map mode, over substantial depression angles (5 to 60 deg) and squint angles (broadside and ±45 deg). Real-time Motion Compensation is implemented to allow high-quality image formation even during vehicle turns and other maneuvers

  2. Earth-Affecting Solar Causes Observatory (EASCO): A Potential International Living with a Star Mission from Sun-Earth L5

    Science.gov (United States)

    Gopalswamy, N.; Davila, J. M.; St Cyr, O. C.; Sittler, E. C.; Auchere, F.; Duvall, Jr. T. L.; Hoeksema, J. T.; Maksimovic, M.; MacDowall, R. J.; Szabo, A.; Collier, M. R.

    2011-01-01

    This paper describes the scientific rationale for an L5 mission and a partial list of key scientific instruments the mission should carry. The L5 vantage point provides an unprecedented view of the solar disturbances and their solar sources that can greatly advance the science behind space weather. A coronagraph and a heliospheric imager at L5 will be able to view CMEs broadsided, so space speed of the Earth-directed CMEs can be measured accurately and their radial structure discerned. In addition, an inner coronal imager and a magnetograph from L5 can give advance information on active regions and coronal holes that will soon rotate on to the solar disk. Radio remote sensing at low frequencies can provide information on shock-driving CMEs, the most dangerous of all CMEs. Coordinated helioseismic measurements from the Sun Earth line and L5 provide information on the physical conditions at the base of the convection zone, where solar magnetism originates. Finally, in situ measurements at L5 can provide information on the large-scale solar wind structures (corotating interaction regions (CIRs)) heading towards Earth that potentially result in adverse space weather.

  3. Microstrip Yagi Antenna with Dual Aperture-Coupled Feed

    Science.gov (United States)

    Pogorzelski, Ronald; Venkatesan, Jaikrishna

    2008-01-01

    A proposed microstrip Yagi antenna would operate at a frequency of 8.4 GHz (which is in the X band) and would feature a mechanically simpler, more elegant design, relative to a prior L-band microstrip Yagi antenna. In general, the purpose of designing a microstrip Yagi antenna is to combine features of a Yagi antenna with those of a microstrip patch to obtain an antenna that can be manufactured at low cost, has a low profile, and radiates a directive beam that, as plotted on an elevation plane perpendicular to the antenna plane, appears tilted away from the broadside. Such antennas are suitable for flush mounting on surfaces of diverse objects, including spacecraft, aircraft, land vehicles, and computers. Stated somewhat more precisely, what has been proposed is a microstrip antenna comprising an array of three Yagi elements. Each element would include four microstrip-patch Yagi subelements: one reflector patch, one driven patch, and two director patches. To obtain circular polarization, each driven patch would be fed by use of a dual offset aperture-coupled feed featuring bow-tie-shaped apertures. The selection of the dual offset bow-tie aperture geometry is supported by results found in published literature that show that this geometry would enable matching of the impedances of the driven patches to the 50-Omega impedance of the microstrip feedline while maintaining a desirably large front-to-back lobe ratio.

  4. The interaction of a magnetohydrodynamical shock with a filament

    CERN Document Server

    Goldsmith, K J A

    2016-01-01

    We present 3D magnetohydrodynamic numerical simulations of the adiabatic interaction of a shock with a dense, filamentary cloud. We investigate the effects of various filament lengths and orientations on the interaction using different orientations of the magnetic field, and vary the Mach number of the shock, the density contrast of the filament, and the plasma beta, in order to determine their effect on the evolution and lifetime of the filament. We find that in a parallel magnetic field filaments have longer lifetimes if they are orientated more 'broadside' to the shock front, and that an increase in the density contrast hastens the destruction of the cloud, in terms of the modified cloud-crushing time-scale, tcs. The combination of a mild shock and a perpendicular or oblique field provides the best condition for extending the life of the filament, with some filaments able to survive almost indefinitely since they are cocooned by the magnetic field. A high value for the density contrast does not initiate la...

  5. A Compact Dielectric Resonator Antenna Excited by a Planar Monopole Patch for Wideband Applications

    Directory of Open Access Journals (Sweden)

    Xuping Li

    2016-01-01

    Full Text Available A compact dielectric resonator antenna (DRA suitable for wideband applications is presented in this paper. The proposed antenna is mainly composed by a notched cylindrical dielectric resonator (DR coated with a metal surface on the top and a finite ground plane where the presented DR is placed. This antenna is very simple in structure and has a very low overall height of 0.14λmin at its lowest operation frequency. A comprehensive parametric study is carried out based on Ansoft HFSS to optimize the bandwidth. The proposed antenna has been successfully simulated, optimized, fabricated, and measured. The measurement results demonstrate that the proposed design produces an impedance bandwidth of more than 75%, ranging from 2.9 GHz to 6.7 GHz for the reflection coefficient less than −10 dB. In particular, consistent broadside radiation patterns, stable gain, and high radiation efficiency are also obtained within the operation frequency band.

  6. Investigation of correlation characteristics for random array collaborative beamforming using noise signals

    Science.gov (United States)

    Alexander, David B.; Narayanan, Ram M.; Himed, Braham

    2016-05-01

    The performance of different random array geometries is analyzed and compared. Three phased array geometries are considered: linear arrays with non-uniform randomized spacing between elements, circular arrays with non-uniform element radii, and ad hoc sensor networks with elements located randomly within a circular area. For each of these array geometries, computer simulations modeled the transmission, reflection from an arbitrary target, and reception of signals. The effectiveness of each array's beamforming techniques was measured by taking the peak cross-correlation between the received signal and a time-delayed replica of the original transmitted signal. For each array type, the correlation performance was obtained for transmission and reception of both chirp waveforms and ultra-wideband noise signals. It was found that the non-uniform linear array generally produced the highest correlation between transmitted and reflected signals. The non-uniform circular and ad hoc arrays demonstrated the most consistent performance with respect to noise signal bandwidth. The effect of scan angle was found to have a significant impact on the correlation performance of the linear arrays, where the correlation performance declines as the scan angle moves away from broadside to the array.

  7. The Design of Monolithic AC-coupled 1-Dimensional Voltage-Controlled-Oscillators (VCOs) Phased-array Network

    Science.gov (United States)

    Lie, Donald Y. C.; Lopez, J.

    2011-04-01

    A fully monolithic 1-Dimensional (1-D) AC-coupled Voltage-Controlled-Oscillators (VCOs) phased-array network design will be presented in this paper. This radio-frequency (RF) VCO array integrates on-chip inductors, varactors and bias current sources and it contains an odd number of VCOs AC-coupled through on-chip switchable resistor networks using MOSFETs. The measured results and SPICE simulated performance of the monolithic unit cell VCO agree reasonably well. Realistic circuit simulations in IBM 7HP 0.18 um BiCMOS design kit indicate promising results of the 1-D coupled-VCO array by showing the design can control the phasing of this on-chip VCO-array by means of tuning the edge elements and/or by varying the coupling strength via different resistor values using the on-chip MOSFET switches. Simulation data shows that it can offer high directivity and a possible element-to-element phase tuning arrangement that allows a ˜±20-30° degree coverage from broadside without the need for phase shifters or additional circuitry complexity. This AC-coupled 1-D VCO array, therefore, shows great potential for RF active antennas applications to perform wide angle beam steering for the highly used S-band.

  8. Antennas Designed for Advanced Communications for Air Traffic Management (AC/ATM) Project

    Science.gov (United States)

    Zakrajsek, Robert J.

    2000-01-01

    The goal of the Advanced Communications for Air Traffic Management (AC/ATM) Project at the NASA Glenn Research Center at Lewis Field is to enable a communications infrastructure that provides the capacity, efficiency, and flexibility necessary to realize a mature free-flight environment. The technical thrust of the AC/ATM Project is targeted at the design, development, integration, test, and demonstration of enabling technologies for global broadband aeronautical communications. Since Ku-band facilities and equipment are readily available, one of the near-term demonstrations involves a link through a Kuband communications satellite. Two conformally mounted antennas will support the initial AC/ATM communications links. Both of these are steered electronically through monolithic microwave integrated circuit (MMIC) amplifiers and phase shifters. This link will be asymmetrical with the downlink to the aircraft (mobile vehicle) at a throughput rate of greater than 1.5 megabits per second (Mbps), whereas the throughput rate of the uplink from the aircraft will be greater than 100 kilobits per second (kbps). The data on the downlink can be narrow-band, wide-band, or a combination of both, depending on the requirements of the experiment. The AC/ATM project is purchasing a phased-array Ku-band transmitting antenna for the uplink from the test vehicle. Many Ku-band receiving antennas have been built, and one will be borrowed for a short time to perform the initial experiments at the NASA Glenn Research Center at Lewis Field. The Ku-band transmitting antenna is a 254-element MMIC phased-array antenna being built by Boeing Phantom Works. Each element can radiate 100 mW. The antenna is approximately 43-cm high by 24-cm wide by 3.3-cm thick. It can be steered beyond 60 from broadside. The beamwidth varies from 6 at broadside to 12 degrees at 60 degrees, which is typical of phased-array antennas. When the antenna is steered to 60 degrees, the beamwidth will illuminate

  9. Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

    International Nuclear Information System (INIS)

    Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B0. Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. It is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B0. The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B0 has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of fundamental interest and of

  10. Evaluation of motorcycle safety strategies using the severity of injuries.

    Science.gov (United States)

    Jung, Soyoung; Xiao, Qin; Yoon, Yoonjin

    2013-10-01

    The growth of motorcycle fatalities in California has been especially prominent, specifically with regard to the 24 and under age group and those aged 45-54. This research quantitatively examined factors associated with motorcyclist fatalities and assessed strategies that could improve motorcyclist safety, specifically focusing on the two age groups mentioned above. Severity of injury was estimated separately for both age groups with multinomial logit models and pseudo-elasticity using motorcycle-related collision data that was collected between 2005 and 2009. The results were compared with motorcyclists aged 35-44, a group that shows a consistent trend of fatalities. This research found that lack or improper use of helmets, victim ejection, alcohol/drug effects, collisions (head-on, broadside, hit-object), and truck involvement were more likely to result in fatal injuries regardless of age group. Weekend and non-peak hour activity was found to have a strong effect in both the younger and older age groups. Two factors, movement of running off the road preceding a collision and multi-vehicle involvement, were found to be statistically significant factors in increasing older motorcyclist fatalities. Use of street lights in the dark was found to decrease the probability of severe injury for older motorcyclists. Driver type of victim, at-fault driver, local road, and speed violation were significant factors in increasing the fatalities of younger motorcyclists. Road conditions and collision location factors were not found to be statistically significant to motorcyclist fatalities. Based on the statistically significant factors identified in this research, the following safety strategies appear to be effective methods of reducing motorcyclist fatalities: public education of alcohol use, promoting helmet use, enforcing heavy vehicle and speed violations, improving roadway facilities, clearer roadway guidance and street lighting systems, and motorcyclist training. PMID

  11. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Science.gov (United States)

    Mitri, F. G.

    2015-12-01

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  12. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology–ETC, Santa Fe, New Mexico 87508 (United States)

    2015-12-07

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  13. Impedance-matching analysis in IR leaky-wave antennas

    Science.gov (United States)

    Premkumar, Navaneeth; Xu, Yuancheng; Lail, Brian A.

    2015-08-01

    Planar leaky-wave antennas (LWA) that are capable of full-space scanning have long since been the pursuit for applications including, but not limited to, integration onto vehicles and into cameras for wide-angle of view beam-steering. Such a leaky-wave surface (LWS) was designed for long-wave infrared frequencies with frequency scanning capability. The LWS is based on a microstrip patch array design of a leaky-wave impedance surface and is made up of gold microstrip patches on a grounded zinc sulphide substrate. A 1D composite right/left-handed (CRLH) metamaterial made by periodically stacking a unit cell of the LWS in the longitudinal direction to form a LWA was designed. This paper deals with loading the LWA with a nickel bolometer to collect leaky-wave signals. The LWA radiates a backward leaking wave at 30 degrees at 28.3THz and scans through broadside for frequencies 20THz through 40THz. The paper deals with effectively placing the bolometer in order for the collected signal to exhibit the designed frequency regime. An effective way to maximize the power coupling into the load from the antenna is also explored. The benefit of such a metamaterial/holographic antennacoupled detector is its ability to provide appreciable capture cross-sections while delivering smart signals to subwavelength sized detectors. Due to their high-gain, low-profile, fast response time of the detector and ease of fabrication, this IR LWA-coupled bolometer harbors great potential in the areas of high resolution, uncooled, infrared imaging.

  14. A MADYMO model of near-side human occupants in side impacts.

    Science.gov (United States)

    Huang, Y; King, A I; Cavanaugh, J M

    1994-05-01

    The protection of automotive occupants against broadside collisions is of current interest due to the implementation of a new Federal standard on side impact. There is controversy as to the validity of the standard, the best criterion to assess injury to the thorax and the type and manner in which padding should be used. Although it has been shown in a series of 17 cadaveric tests that paper honeycomb can reduce thoracic injuries dramatically, there are still concerns regarding the loss of air space between the door and the occupant due to the presence of the padding and regarding the loss of protection for the thorax when there is no engagement of the shoulder with the intruding side structure of the car. This paper describes the development of a three-dimensional rigid body model to simulate cadaveric experiments carried out at Wayne State University. Model parameters were chosen to yield human-like responses at the level of the shoulder, thorax, abdomen and pelvis. The model was then used to study the effect of padding on injury parameters related to the nearside occupant when a relatively thick padding is used (up to 100 mm). It was also used to study the increase in force on the thorax when shoulder engagement is lost. Laboratory tests were conducted with full shoulder engagement but in the field most cars have a low beltline (window sill) which effectively eliminates shoulder contact if the arms are outstretched in a normal driving posture. If a sufficiently soft padding was used, the model did not predict an increase in thoracic force level or any of the injury parameters.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8078331

  15. Calibration and Validation of Airborne InSAR Geometric Model

    International Nuclear Information System (INIS)

    The image registration or geo-coding is a very important step for many applications of airborne interferometric Synthetic Aperture Radar (InSAR), especially for those involving Digital Surface Model (DSM) generation, which requires an accurate knowledge of the geometry of the InSAR system. While the trajectory and attitude instabilities of the aircraft introduce severe distortions in three dimensional (3-D) geometric model. The 3-D geometrical model of an airborne SAR image depends on the SAR processor itself. Working at squinted model, i.e., with an offset angle (squint angle) of the radar beam from broadside direction, the aircraft motion instabilities may produce distortions in airborne InSAR geometric relationship, which, if not properly being compensated for during SAR imaging, may damage the image registration. The determination of locations of the SAR image depends on the irradiated topography and the exact knowledge of all signal delays: range delay and chirp delay (being adjusted by the radar operator) and internal delays which are unknown a priori. Hence, in order to obtain reliable results, these parameters must be properly calibrated. An Airborne InSAR mapping system has been developed by the Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences (CAS) to acquire three-dimensional geo-spatial data with high resolution and accuracy. To test the performance of the InSAR system, the Validation/Calibration (Val/Cal) campaign has carried out in Sichun province, south-west China, whose results will be reported in this paper

  16. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    Science.gov (United States)

    Sarman, Sten; Wang, Yong-Lei; Laaksonen, Aatto

    2016-02-01

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small.

  17. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    International Nuclear Information System (INIS)

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small

  18. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    Energy Technology Data Exchange (ETDEWEB)

    Sarman, Sten, E-mail: sarman@ownit.nu; Wang, Yong-Lei; Laaksonen, Aatto [Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm (Sweden)

    2016-02-07

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small.

  19. NUMERICAL PREDICTION OF PROPELLER EXCITED ACOUSTIC RESPONSE OF SUBMARINE STRUCTURE BASED ON CFD, FEM AND BEM

    Institute of Scientific and Technical Information of China (English)

    WEI Ying-san; WANG Yong-sheng; CHANG Shu-ping; FU Jian

    2012-01-01

    A mesh-less Refined Integral Algorithm (RIA) of Boundary Element Method (BEM) is proposed to accurately solve the Helmholtz Integral Equation (HIE).The convergence behavior and the practicability of the method are validated.Computational Fluid Dynamics (CFD),Finite Element Method (FEM) and RIA are used to predict the propeller excited underwater noise of the submarine hull structure.Firstly the propeller and submarine's flows are independently validated,then the self propulsion of the “submarine+propeller” system is simulated via CFD and the balanced point of the system is determined as well as the self propulsion factors.Secondly,the transient response of the “submarine + propeller” system is analyzed at the balanced point,and the propeller thrust and torque excitations are calculated.Thirdly the thrust and the torque excitations of the propeller are loaded on the submarine,respectively,to calculate the acoustic response,and the sound pover and the main peak frequencies are obtained.Results show that:(1) the thrust mainly excites the submarine axial mode and the high frequency area appears at the two conical-type ends,while the torque mainly excites the circumferential mode and the high frequency area appears at the broadside of the cylindrical section,but with rather smaller sound power and radiation efficiency than the former,(2) the main sound source appears at BPF and 2BPF and comes from the harmonic propeller excitations.So,the main attention should be paid on the thrust excitation control for the sound reduction of the propeller excited submarine structure.

  20. Refined acoustic modeling and analysis of shotgun microphones.

    Science.gov (United States)

    Bai, Mingsian R; Lo, Yi-Yang

    2013-04-01

    A shotgun microphone is a highly directional pickup device widely used in noisy environments. The key element that leads to its superior directivity is a tube with multiple slot openings along its length. One traditional way to model the directional response of a shotgun is to assume plane waves traveling in the tube as if it is in the free field. However, the frequency response and directivity predicted by this traveling wave model can differ drastically from practical measurements. In this paper, an in-depth electroacoustic analysis was conducted to examine the problem by considering the standing waves inside the tube with an analogous circuit containing phased pressure sources and T-networks of tube segments. A further refinement is to model the housing diffraction effect with the aid of the equivalent source method (ESM). The on-axis frequency response and directivity pattern predicted by the proposed model are in close agreement with the measurements. From the results, a peculiar bifurcation phenomenon of directivity pattern at the Helmholtz frequency was also noted. While the shotgun behaves like an endfire array above the Helmholtz frequency, it becomes a broadside array below the Helmholtz frequency. The standing wave effect can be mitigated by covering the slot openings with mesh screen, which was found to alter the shotgun response to be closer to that of the traveling wave model above a critical frequency predicted by the half-wavelength rule. A mode-switching model was developed to predict the directional responses of mesh-treated shotguns. PMID:23556574

  1. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    International Nuclear Information System (INIS)

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries

  2. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Science.gov (United States)

    Mitri, F. G.

    2015-12-01

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  3. A study of multilayer passive components for uniplanar MMICs

    International Nuclear Information System (INIS)

    This thesis is concerned with the modelling, design, and characterisation of passive components on Gallium Arsenide (GaAs) and silicon substrates at microwave and millimeter-wave frequencies. The passive components are a vital part of all monolithic microwave integrated circuits (MMICs) because they are used as building blocks to design much larger and more complicated circuits which may employ many active devices. The initial building blocks not only shape the overall performance but also contribute to the final layout and cost depending on how compact these components are. Therefore, this thesis looks at techniques that can be used to achieve higher levels of integration of microwave circuitry and to overcome the need for through-substrate via holes and related back-face processing steps. Topics such as coplanar waveguide (CPW) and multilayer techniques have been covered with this aim. This work begins with an introduction to MMIC design. This is followed by a look at how computer aided design (CAD) packages can be used to enhance circuit design at microwave frequencies. A detailed practical investigation into multilayer structures on GaAs and silicon substrates is undertaken. In order to analyse these structures test masks have been prepared and fabricated. These structures have been characterised and verified with measurements where possible. For the first time, two types of novel multilayer 14-36 GHz MMIC CPW coupled-line 3 dB directional couplers have been realised by using a three metal level MMIC process. The couplers incorporate both broadside and edge coupling in order to obtain a tight coupling. A new method of realising compact baluns at millimeter-wave frequencies is presented and its operation is explained. The analysis has been verified with practical baluns which employed multilayer CPW directional couplers. An alternative balun for lower frequencies has also been proposed and successfully demonstrated experimentally using compact spiral couplers

  4. Radiation forces and torque on a rigid elliptical cylinder in acoustical plane progressive and (quasi)standing waves with arbitrary incidence

    Science.gov (United States)

    Mitri, F. G.

    2016-07-01

    This paper presents two key contributions; the first concerns the development of analytical expressions for the axial and transverse acoustic radiation forces exerted on a 2D rigid elliptical cylinder placed in the field of plane progressive, quasi-standing, or standing waves with arbitrary incidence. The second emphasis is on the acoustic radiation torque per length. The rigid elliptical cylinder case is important to be considered as a first-order approximation of the behavior of a cylindrical fluid column trapped in air because of the significant acoustic impedance mismatch at the particle boundary. Based on the rigorous partial-wave series expansion method in cylindrical coordinates, non-dimensional acoustic radiation force and torque functions are derived and defined in terms of the scattering coefficients of the elliptic cylinder. A coupled system of linear equations is obtained after applying the Neumann boundary condition for an immovable surface in a non-viscous fluid and solved numerically by matrix inversion after performing a single numerical integration procedure. Computational results for the non-dimensional force components and torque, showing the transition from the progressive to the (equi-amplitude) standing wave behavior, are performed with particular emphasis on the aspect ratio a/b, where a and b are the semi-axes of the ellipse, the dimensionless size parameter, as well as the angle of incidence ranging from end-on to broadside incidence. The results show that the elliptical geometry has a direct influence on the radiation force and torque, so that the standard theory for circular cylinders (at normal incidence) leads to significant miscalculations when the cylinder cross section becomes non-circular. Moreover, the elliptical cylinder experiences, in addition to the acoustic radiation force, a radiation torque that vanishes for the circular cylinder case. The application of the formalism presented here may be extended to other 2D surfaces of

  5. A Design of Experiments Investigation of Offset Streams for Supersonic Jet Noise Reduction

    Science.gov (United States)

    Henderson, Brenda; Papamoschou, Dimitri

    2014-01-01

    An experimental investigation into the noise characteristics of a dual-stream jet with four airfoils inserted in the fan nozzle was conducted. The intent of the airfoils was to deflect the fan stream relative to the core stream and, therefore, impact the development of the secondary potential core and noise radiated in the peak jet-noise direction. The experiments used a full-factorial Design of Experiments (DoE) approach to identify parameters and parameter interactions impacting noise radiation at two azimuthal microphone array locations, one of which represented a sideline viewing angle. The parameters studied included airfoil angle-of-attack, airfoil azimuthal location within the fan nozzle, and airfoil axial location relative to the fan-nozzle trailing edge. Jet conditions included subsonic and supersonic fan-stream Mach numbers. Heated jets conditions were simulated with a mixture of helium and air to replicate the exhaust velocity and density of the hot jets. The introduction of the airfoils was shown to impact noise radiated at polar angles in peak-jet noise direction and to have no impact on noise radiated at small and broadside polar angles and to have no impact on broadband-shock-associated noise. The DoE analysis showed the main effects impacting noise radiation at sideline-azimuthal-viewing angles included airfoil azimuthal angle for the airfoils on the lower side of the jet near the sideline array and airfoil trailing edge distance (with airfoils located at the nozzle trailing edge produced the lowest sound pressure levels). For an array located directly beneath the jet (and on the side of the jet from which the fan stream was deflected), the main effects impacting noise radiation included airfoil angle-of-attack and airfoil azimuthal angle for the airfoils located on the observation side of the jet as well and trailing edge distance. Interaction terms between multiple configuration parameters were shown to have significant impact on the radiated

  6. How Robust are Science-Based Disaster Preparedness Strategies? Lessons from Western Sumatra (Invited)

    Science.gov (United States)

    Shannon, R.; McCloskey, J.; McDowell, S.

    2009-12-01

    Forecasts of the next likely megathrust earthquake which will occur off the western coast of Sumatra, possibly in the near future, indicate that it will likely be tsunamigenic and could be more devastating than the 2004 event. Hundreds of simulations of potential earthquakes and their tsunamis show that, while the earthquake is fundamentally unpredictable, many scenarios would see dangerous inundation of low-lying areas along the west coast of Sumatra; the cities of Padang and Bengkulu broadside-on to the areas of highest seismic potential have a combined population of over one million. Understanding how the science of unpredictable, high probability events is absorbed by society is essential for the development of effective mitigation and preparedness campaigns. A five month field investigation conducted in Padang and Bengkulu aimed to conceptualise the main issues driving risk perception of tsunami hazard, and explore its influence upon preparedness. Of specific interest was the role of scientifically quantified hazard information upon risk perception and hazard preparedness. Target populations were adult community members (n=270) and senior high school students (n=90). Preliminary findings indicate that scientific knowledge of earthquake and tsunami threat amongst respondents in both cities is good. However the relationship between respondent’s hazard knowledge, desired risk perception, and the adoption of preparedness measures was often non-linear and is susceptible to the negative effects of unscientific forecasts disseminated by government and mass media. Evidence suggests that ‘mystic’ predictions often portrayed in the media as being scientific, have been readily absorbed by the public; when these fail to materialise the credibility of authentic science and scientists plummets. As a result levels of sustainable earthquake and tsunami preparedness measures adopted by those living in tsunami threatened areas can be detrimentally impacted. It is

  7. Modelling and interpretation of marine controlled source electromagnetic data

    Energy Technology Data Exchange (ETDEWEB)

    Bhuiyan, Anwar Hossain

    2009-09-15

    This thesis aims to (i) interpret the marine CSEM (Controlled Source Electromagnetics) data acquired over offshore Angola, Modgunn arch in the Norwegian Sea and Troll West Gas Providence (TWGP), offshore Norway, (ii) evaluate the effects of acquisition parameters and multi-resistor structures on CSEM responses, and (iii) investigate the time-lapse CSEM sensitivity with respect to changes in saturation and geometry of resistive pore-fluids. Three-dimensional (3D) finite difference time domain (FDTD) forward modelling is used to find correspondence between subsurface resistivity structures and measured data, and also to evaluate CSEM sensitivity and time-lapse anomalies. The electric field magnitudes measured above the proven HC reservoirs offshore Angola are 1.5-3 times higher compared to the synthetic background responses and 'off-reservoir' measurements, while the responses above a salt structure is >3 times stronger compared to the background responses. The CSEM anomaly observed at Modgunn arch, corresponding to high-resistivity sills 1100 m below the seabed, is 2.5 times stronger compared to the background responses. The CSEM data measured above the TWGP (2.7 times stronger compared to 'offreservoir' measurements), also indicate subsurface HCs. CSEM responses obtained from forward modelling, based on seismic and petrophysical data, show good agreement to the measured responses. Combined use of seismic, petrophysical and CSEM data improves the subsurface interpretation. Additionally, introduction of non-HC related high-resistivity structures, such as salt bodies, igneous sills and shallow resistors within the geo-resistivity model improves the subsurface interpretation. Fine grid (1x1 km) acquisition geometry, irrespective of source orientation, provides precise definition of CSEM anomalies. Broadside data in grid geometry increase the data density (up to the factor of 3) and hence improve the CSEM attribute resolution. Source orientation

  8. Terahertz Quantum-Cascade Transmission-Line Metamaterials

    Science.gov (United States)

    Tavallaee, Amir Ali

    Terahertz quantum-cascade (QC) lasers operating at 0.6 - 5 THz (λ ˜ 60 - 500 µm) are poised to become the dominant solid-state sources of continuous-wave (cw) far-infrared radiation enabling applications in terahertz spectroscopy, imaging, and sensing. QC-lasers are the longest wavelength semiconductor laser sources in which terahertz gain is obtained from electronic intersubband radiative transitions in GaAs/AlGaAs heterostructure quantum wells. Since their invention in 2001, rapid development has enabled demonstration of cw powers greater than 100 mW. However, challenges still remain in the areas of operating temperature, laser efficiency and power, and beam quality to name a few. The highest-temperature operation of terahertz quantum-cascade lasers (200 K pulsed, 117 K cw) depends on the use of a low-loss "metal-metal" waveguide where the active gain material is sandwiched between two metal cladding layers; a technique similar, in concept, to microstrip transmission line technology at microwave frequencies. Due to the subwavelength transverse dimensions of the metal-metal waveguide, however, obtaining a directive beam pattern and efficient out-coupling of THz power is non-trivial. This thesis reports the demonstration of a one-dimensional waveguide for terahertz quantum-cascade lasers that acts as a leaky-wave antenna and tailors laser radiation in one dimension to a directional beam. This scheme adapts microwave transmission-line metamaterial concepts to a planar structure realized in terahertz metal-metal waveguide technology and is fundamentally different from distributed feedback/photonic crystal structures that work based on Bragg scattering of propagating modes. The leaky-wave metamaterial antenna operates based on a propagating mode with an effective phase index smaller than unity such that it radiates in the surface direction via a leaky-wave mechanism. Surface emission (˜ 40° from broadside) with a single directive beam (FWHM ˜ 15°) at 2.74 THz

  9. Theory of a Traveling Wave Feed for a Planar Slot Array Antenna

    Science.gov (United States)

    Rengarajan, Sembiam

    2012-01-01

    Planar arrays of waveguide-fed slots have been employed in many radar and remote sensing applications. Such arrays are designed in the standing wave configuration because of high efficiency. Traveling wave arrays can produce greater bandwidth at the expense of efficiency due to power loss in the load or loads. Traveling wave planar slot arrays may be designed with a long feed waveguide consisting of centered-inclined coupling slots. The feed waveguide is terminated in a matched load, and the element spacing in the feed waveguide is chosen to produce a beam squinted from the broadside. The traveling wave planar slot array consists of a long feed waveguide containing resonant-centered inclined coupling slots in the broad wall, coupling power into an array of stacked radiating waveguides orthogonal to it. The radiating waveguides consist of longitudinal offset radiating slots in a standing wave configuration. For the traveling wave feed of a planar slot array, one has to design the tilt angle and length of each coupling slot such that the amplitude and phase of excitation of each radiating waveguide are close to the desired values. The coupling slot spacing is chosen for an appropriate beam squint. Scattering matrix parameters of resonant coupling slots are used in the design process to produce appropriate excitations of radiating waveguides with constraints placed only on amplitudes. Since the radiating slots in each radiating waveguide are designed to produce a certain total admittance, the scattering (S) matrix of each coupling slot is reduced to a 2x2 matrix. Elements of each 2x2 S-matrix and the amount of coupling into the corresponding radiating waveguide are expressed in terms of the element S11. S matrices are converted into transmission (T) matrices, and the T matrices are multiplied to cascade the coupling slots and waveguide sections, starting from the load end and proceeding towards the source. While the use of non-resonant coupling slots may provide an

  10. Vertical and wide-angle seismic exploration of crustal structure, and the active evolution of the North Aegean Trough between the Sea of Marmara and Gulf of Corinth

    Science.gov (United States)

    Sachpazi, M.; Vigner, A.; Laigle, M.; Hirn, A.; Roussos, N.

    2003-04-01

    and reflectors interpreted as the top and the base of the lower crust. Based on the consistency of seismic evidence over the different profiles, though this is faint on each taken by itself, clear basement-involving faults that appear tosole into an upper crustal reflective domain which is interpreted as a shallow dipping detachment. These profiles reveal also uppercrustal structures consistent with the evolution in time and space of such a detachment. The latter has low angle dip grossly northeastward, from very shallow under the base of sediments in the SW corner of the NAT (N of Sporadhes Islands) to the 10 km depth where the active normal fault on the northern slope has been imaged. It is imaged in a joint consideration of the pres-stack depth migrated line and of the stack with multiple-suppression. Beneath, the top of the lower crust and the Moho are imaged in places. In-line and broadside wide-angle recordings by stations along the Magnesian peninsula and Evvia detect an abnormaly shallow position and facies of the lower crust under the southwestern edge of the NAT. Its extent is limited by the southern and western edges of the NAT and it can be viewed as marking the location of largest finite thinning of the upper crust. Striction and transport along the detachment are suggested to occur by the drag of the SW transported southern limb to the North Anatolian fault at the North Sporadhes escarpment.

  11. Analysis on traffic accident caused by dump truck in Shanghai, 2006-2009%2006-2009年上海市自卸货车及全市交通事故特征分析

    Institute of Scientific and Technical Information of China (English)

    喻彦; 侯心一; 周峰; 周德定; 苏慧佳; 高宁

    2012-01-01

    truck were severity, 98.1% of them were accompany with injuries. The traffic accidents mostly happened in summer and fall, and were concentrated between 12: 00 -18: 00 in a day. However, the accidents caused by dump trunk mostly happened in summer and were concentrated in two time period which were between 6:00 -12:00 or 12:00 -18:00. In traffic accidents caused by dump truck and other road traffic accidents, most of drivers were young men. The primary reason of accidents was motor vehicle illegal, 63. 8% in road traffic accidents and 73. 0% in accidents caused by dump truck. The main collided position of vehicle were broadside (53.0% in road traffic accidents and 53. 0% in accidents caused by dump truck) , head-on (20.7% in road traffic accidents and 17. 3% in accidents caused by dump truck) and rear-end (8. 8% in road traffic accidents and 8.1% in accidents caused by dump truck). Conclusion The road traffic injury caused by dump truck is a severe problem, comprehensive intervention focused on personnel, vehicle and road should be carried out among residents to decrease road traffic accidents.

  12. Traffic accidents with motorcycles and their relationship to mortality Ocurrencias de tránsito con motocicleta y su relación con la mortalidad Ocorrências de trânsito com motocicleta e sua relação com a mortalidade

    Directory of Open Access Journals (Sweden)

    Nelson Luiz Batista de Oliveira

    2011-04-01

    Full Text Available This study characterizes traffic accidents involving motorcycles according to local conditions, data concerning the type of accident, date and time, and identifies among these variables those associated with the death of victims. This retrospective study uses data from traffic collision reports from 2004 and death records from the institute of forensic medicine. A total of 99.4% of the events occurred in urban areas, where illumination (87.4%, weather conditions (80.6%; and traffic signs (70.6% were satisfactory. Collisions between motorcycles and cars or pickup trucks prevailed (55.5%, followed by motorcycle falls (18.0%. In relation to the type of collision, the highest percentage was observed in broadside collision category (35.2%. There were differences between the groups of fatalities and survivors in relation to the area and illumination in the collision’s site, in addition to the types of collision and impact. The conclusion is that local conditions and types of collision and impact stand out among the multiple variables defining the severity of accidents involving motorcycles.Se tuvo por objetivo caracterizar las ocurrencias de tránsito con motocicleta, según condiciones locales, datos relacionados al tipo de accidente, fecha y hora, además de identificar entre esas variables las que se asociaron con la muerte de las víctimas. Se trata de un estudio retrospectivo utilizando datos de los Boletines de Ocurrencia de Tránsito referentes al año de 2.004 y los registros de muerte del Instituto Médico Legal. El 99,4% de las ocurrencias sucedieron en área urbana, en locales donde las condiciones de luminosidad (87,4%, condición meteorológica (80,6% y señalización (70,6% eran satisfactorias. Predominó la colisión de motocicleta con automóvil o camioneta (55,5% y las caídas de motocicleta fueron las más frecuentes (18,0%. En el tipo de impacto, el mayor porcentaje fue observado en la categoría colisión transversal (35,2%. El