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Method for fabricating a temperature compensated surface wave device - Patent 4006435 Disclosed is a method for fabricating an acoustic surface wave device having reduced temperature coefficient of propagation delay within a desired range of operating temperatures. The approximate path length of surface waves traveling between transducer 34 and transducer 36 is indicated by length 44 which is between the center of transducer 34 and the center of transducer 36. The effect of a metallic deposit on the propagating surface of an acoustic surface wave device in changing the temperature of zero temperature coefficient of propagation delay is particularly useful for an AT-cut quartz crystal. www.freepatentsonline.com /4006435.html   (3200 words)

Raytheon Company: Products & Services: High Frequency Surface Wave Radar (HFSWR) HFSWR (High-Frequency Surface Wave Radar) is a rapidly-deployed, low-cost system designed to detect and track ships and low-flying aircraft to beyond the 200 nautical mile limit. HF surface wave radars are ideally suited to surveillance of the EEZ (Exclusive Economic Zone). For surveillance of surface vessels and low-flying aircraft beyond 30 nautical miles, the only alternative up to now has been to operate from shipboard and airborne platforms, where the costs of providing surveillance are very high and 24-hour, all-weather surveillance is simply not practical. www.raytheon.com /products/hfswr   (320 words)

Definition: surface wave surface wave: A wave that is guided along the interface between two different media or by a refractive index gradient. Note 2: Optical energy is not converted from the surface wave field to another form of energy and the wave does not have a component directed normal to the interface surface. Note 4: In radio transmission, ground waves are surface waves that propagate close to the surface of the Earth, the Earth having one refractive index and the atmosphere another, thus constituting an interface surface. www.atis.org /tg2k/_surface_wave.html   (127 words)

What Is Seismology and What Are Seismic Waves? Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. Subjected to a P wave, particles move in the same direction that the the wave is moving in, which is the direction that the energy is traveling in, and is sometimes called the 'direction of wave propagation'. S waves move rock particles up and down, or side-to-side--perpindicular to the direction that the wave is traveling in (the direction of wave propagation). www.geo.mtu.edu /UPSeis/waves.html   (817 words)

Substrate usable for an acoustic surface wave device, a method for fabricating the same substrate and an acoustic ... An acoustic surface wave device as defined in claim 3, wherein the substrate includes a surface nitride layer at the main surface of the base material on which the AlN film is formed. Therefore, the substrate cannot be practically usable for the acoustic surface wave device as is. For practical use, the substrate is required to be polished. Since the thickness of the surface nitride layer depends on the nitrogen concentration, the nitriding temperature, the nitriding period or the like, it is determined to a given value by controlling their conditions appropriately. www.freepatentsonline.com /6815867.html   (2817 words)

Longitudinal and Transverse Wave Motion Mechanical Waves are waves which propagate through a material medium (solid, liquid, or gas) at a wave speed which depends on the elastic and inertial properties of that medium. The wave is seen as the motion of the compressed region (ie, it is a pressure wave), which moves from left to right. The particles in a solid, through which a Rayleigh surface wave passes, move in elliptical paths, with the major axis of the ellipse perpendicular to the surface of the solid. www.kettering.edu /~drussell/Demos/waves/wavemotion.html   (528 words)

Broadband surface wave dispersion measurements across North America from ambient seismic noise Cross- correlations of the ambient wavefield between pairs of receivers can be used to extract the Rayleigh wave part of Green's function and, therefore, provide a new source of surface wave information that is particularly useful in the context of arrays of broadband seismometers such as PASSCAL experiments, the emerging USArray, or other national deployments. The method to extract surface wave dispersion measurements from ambient noise was first applied systematically to records from USArray Transportable Array stations in California. These observations were used to construct high-resolution short-period (7-18 s) surface wave dispersion maps and to image the principal crustal geological units. www.agu.org /cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=sm05&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=bensen&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2fsm05%2fsm05%7c566%7c4052%7cBroadband%20surface%20wave%20dispersion%20measurements%20across%20North%20America%20from%20ambient%20seismic%20noise%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2fsm05%2fsm05%7c6857051%206861103%20%2fdata2%2fepubs%2fwais%2fdata%2fsm05%2fsm05.txt   (375 words)

SURFACE WAVE The ground wave is actually composed of two separate component waves. As a surface wave passes over the ground, the wave induces a voltage in the Earth. The wave is then completely attenuated within a short distance from the transmitting site. www.tpub.com /content/neets/14182/css/14182_76.htm   (307 words)

IntelliTouch surface wave touchscreens - Elo TouchSystems - Tyco Electronics IntelliTouch surface wave is the optical standard of touch. IntelliTouch is widely used in kiosk, gaming, and office automation applications and is available for both flat panel and CRT solutions. Surface wave (also known as surface acoustic wave, or SAW) technology www.elotouch.com /Products/Touchscreens/IntelliTouch   (204 words)

Rediscovering the Zenneck Surface Wave This wave is the result of electrical currents induced in the ground by refraction of a portion of the reflected-wave component at the earth-atmosphere interface. The Tesla antenna is a form of wireless antenna or wave launching structure developed by Nikola Tesla in which the transmitted energy propagates or is carried to the receiver by a combination of electrical current flowing through the earth, electrostatic induction and electrical conduction through plasma with an embedded magnetic field. And, while the Norton Surface Wave is the result of electrical currents induced in the ground by refraction of a portion of the reflected-wave component of the ground-wave at the earth-atmosphere interface, the surface wave associated with Tesla’s apparatus is the result of electrical ground currents flowing between two discrete points on the earth’s surface. www.tfcbooks.com /articles/tws4.htm   (1669 words)

Surface Wave Theory Page Surface waves are generated by the constructive interference of incident P and S -waves arriving at the free surface and propagating parallel to the surface. The amplitude of surface waves decreases with increasing depth and are affected by lateral variations in structure. Another property that surface waves exhibit is Dispersion, where the velocity of a wave on the surface is dependent on its frequency (or period). www.uwm.edu /~bketter/Research/Surface_Theory/Surface.html   (444 words)

Definition of Surface-wave-sustained mode The wave is reflected at the plasma surface due to the skin effect and becomes an evanescent wave. The wave energy is then transferred to the plasma by an evanescent wave which enters the plasma perpendicular to its surface and decays exponentially with the skin depth. Surface wave plasma sources can be divided into two groups depending upon whether the plasma generates part of its own waveguide by ionisation or not. www.wordiq.com /definition/Surface-wave-sustained_mode   (365 words)

Bambooweb: Surface wave In physics, a surface wave is a wave that is guided along the interface between two different media for a mechanical wave, or by a refractive index gradient for an electromagnetic wave. Optical energy is not converted from the surface wave field to another form of energy and the wave does not have a component directed normal to the interface surface. In radio transmission, ground waves are surface waves that propagate close to the surface of the Earth, the Earth having one refractive index and the atmosphere another, thus constituting an interface surface. www.bambooweb.com /articles/S/u/Surface_wave.html   (196 words)

The Physics Classroom One way to categorize waves is on the basis of the direction of movement of the individual particles of the medium relative to the direction which the waves travel. While waves which travel within the depths of the ocean are longitudinal waves, the waves which travel along the surface of the oceans are referred to as surface waves. In longitudinal and transverse waves, all the particles in the entire bulk of the medium move in a parallel and a perpendicular direction (respectively) relative to the direction of energy transport. www.physicsclassroom.com /Class/waves/u10l1c.html   (1558 words)

Surface acoustic wave filter   (Site not responding. Last check: ) First of all, surface waves are readily reflected by the edges of the substrate, resulting in a direct echo that may be received by the receiving transducer. These waves if generated by the transducer which is supposed to be only a receiver, travel back to the original transmitter and interact therewith in like manner, whereupon surface waves are generated thereat which will reach again the receiver. Moreover, the echo signals produced when a surface wave receiving transducer retransmits surface waves (e.g., triple transit echos) are hidden in the amplifier recovery period, and reflected surface waves, reflected by the substrate edges, are attenuated and redirected and contribute very little to receiver response. www.sacnewsmonthly.com /invent/filter_rod_machine/surface_acoustic_wave_filter.html   (3396 words)

Elastic surface wave device   (Site not responding. Last check: ) voltage is applied to the semiconductor in a direction along the surface of the semiconductor which defines the gap to accomplish an amplifying operation by the interaction between a semiconductor charge and a surface wave caused by such application of the d.c. It is therefore an object of the present invention to provide an elastic surface wave device which comprises a laminate formed of a semiconductor layer and a piezoelectric layer and a metal electrode for supply of a d.c. As the elastic surface wave amplifier in accordance with the present invention is so adapted that the surface wave signal may be amplified through the parametric amplification effect caused by supplying an a.c. www.sacnewsmonthly.com /invent/conveyor/elastic_surface_wave.html   (2286 words)

[No title]   (Site not responding. Last check: ) The surface waves arrive after the S waves because surface wave velocities in rocks are lower than the shear wave velocity. The surface waves extend over a long time interval because surface wave propagation is dispersive (the velocity of propagation is dependent on the frequency of the wave). The first shear wave motion (illustrated in the particle motion diagram in the lower left of Figure 9) is arriving from down and to the south (diagonally from the lower left in the particle motion diagram). web.ics.purdue.edu /~braile/edumod/waves/WaveDemo.htm   (4491 words)

Palisades guide - Surface waves   (Site not responding. Last check: ) Surface waves travel along the surface of the Earth instead of passing through the interior. For most teleseismic events, surface waves are easy to identify on seismograms for two reasons - surface waves have large amplitudes and their primary arrivals can be spread over many tens of minutes. As a result, the amplitude of surface waves is quite sensitive to the depth of the event. www.ldeo.columbia.edu /~mwest/palguide/surface.html   (1032 words)

Oceanography: waves However, the surface waves between two media (water and air), behave very different and solely under the influence of gravity, which is much weaker than that of elastic compression, the method by which sound propagates. Surface waves, however, are limited by the density of water and the pull of gravity. The continental shelf of 100m is a very shallow area for these waves and they rise, form steep crests and very large horizontal water movements, which over-run low lying areas, rip boats from their moorings and may bare the sea to a depth of 5m or splash against the coast to a height of 20-30m. www.seafriends.org.nz /oceano/waves.htm   (8841 words)

surface acoustic wave filter at Filtronetics, Inc. Surface acoustic wave filters, commonly known as SAW filters, are used primarily as bandpass and bandstop filters. A surface acoustic wave filter is manufactured on a substrate of quartz or lithium niobate by applying thin layers of metal. The wave is launched across the substrate to another IDT that converts the mechanical energy back to electrical. www.filtro.net /content/surface_acoustic_wave_filter.html   (437 words)

Electromagnetic Surface Waves The analysis and use of surface waves (see note on terminology) for remote sensing (of the sea surface, targets,...) have a long history dating back to the beginning of the century. This so-called Zenneck wave is simply a vertically polarized plane wave solution to Maxwell's equations in the presence of a planar boundary that separates free space from a half space with a finite conductivity. The term surface wave conjures up an image of energy flow that is confined to a region that is localized at or near the surface. web.mit.edu /redingtn/www/netadv/zenneck.html   (1172 words)

CAMEX-3 JPL Surface Acoustic Wave (SAW) Hygrometer Condensation is detected optically by monitoring the reflectivity of the mirror, and the temperature of the mirror is controlled to maintain an equilibrium between condensation and evaporation in the presence of changing humidity. On the one hand, the presence of salt on the SAW surface may explain the tendency of the SAW hygrometer to measure dewpoint (as opposed to frostpoint). As long as the thermistor which monitors the surface temperature is accurate, the output should be an indication of the dewpoint/frostpoint. microwave.msfc.nasa.gov:5721 /dataset_documents/dc8jplsaw_dataset.html   (2434 words)

School of Civil and Environmental Engineering   (Site not responding. Last check: ) Surface wave tests are used to determine the small-strain properties (i.e. The primary advantage of surface wave tests is that they are non-invasive. Surface wave research at Georgia Tech is focusing on extending the capabilities of surface wave testing via advances in wave propagation theory, signal processing, and inversion. www.ce.gatech.edu /~grix/surface_wave.html   (450 words)

Ultrasonic Longitudinal and Surface Wave Methods for Monitoring of Damage in Metal Matrix and Ceramic Matrix Composites Surface waves were used to identify the onset of surface and near-surface cracks in CMC. Longitudinal wave propagation was successfully used to monitor the changes in the stiffness of the composite during fatigue loading conditions of CMC and MMC. The changes in the peak-to-peak amplitude of the transmitted wave signal appears to be an equal or better indicator of impending failure of the composite than the extensometer data. www.astm.org /DIGITAL_LIBRARY/STP/PAGES/STP11899S.htm   (281 words)

Extending Ambient Noise Surface Wave Tomography to Continental Scales: Application Across the United States AB: Ambient seismic noise contains a significant component of surface wave energy from which the Rayleigh wave Green function between pairs of stations can be extracted by cross-correlating long noise sequences. Surface wave tomography based on group velocities obtained on the estimated Green functions has been shown to produce high-resolution short-period (7-18 s) surface wave dispersion maps that image the principal crustal geological units in Southern California (Shapiro et al., Science, 307, 1615, 2005). They provide tighter constraints on crustal and upper mantle shear wave speeds and help to bridge the gap between global and regional scale 3-D models. www.agu.org /cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm05&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=bensen&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm05%2ffm05%7c583%7c3654%7cExtending%20Ambient%20Noise%20Surface%20Wave%20Tomography%20to%20Continental%20Scales:%20Application%20Across%20the%20United%20States%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm05%2ffm05%7c26668493%2026672147%20%2fdata2%2fepubs%2fwais%2fdata%2ffm05%2ffm05.txt   (373 words)

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