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Sample records for arecibo uhf observations

  1. An attempt to calibrate the UHF strato-tropospheric radar at Arecibo using NexRad radar and disdrometer data

    Directory of Open Access Journals (Sweden)

    P. Kafando

    2004-12-01

    Full Text Available The goal of this paper is to present a methodology to calibrate the reflectivity of the UHF Strato-Tropospheric (ST radar located at NAIC in Puerto Rico. The UHF lower relevant altitude is at 5.9km, the melting layer being at around 4.8km. The data used for the calibration came from the observations of clouds, carried out with Strato-Tropospheric dual-wavelength (UHF and VHF radars and a disdrometer; those instruments being located on the NAIC site in Arecibo, Puerto Rico. The National Weather Service operates other instruments like the radiosondes and the NexRad Radar in other sites.

    The proposed method proceeds in two steps. The first consists of the comparison between the NexRad reflectivity and the reflectivity computed from the drop size distributions measured by the disdrometer for one day with a noticeable rainfall rate. In spite of the distance of both instruments, the agreement between the reflectivities of both instruments is enough good to be used as a reference for the UHF ST radar. The errors relative at each data set is found to be 2.75dB for the disdrometer and 4dB for the NexRad radar, following the approach of Hocking et al. (2001. The inadequacy between the two sampled volume is an important contribution in the errors.

    The second step consists of the comparison between the NexRad radar reflectivity and the UHF non-calibrated reflectivity at the 4 altitudes of common observations during one event on 15 October 1998. Similar features are observed and a coefficient is deduced. An offset around 4.7dB is observed and the correlation factor lies between 0.628 and 0.730. According to the errors of the data sets, the precision on the calibration is of the order of 2dB. This method works only when there are precipitation hydrometeors above the NAIC site. However, the result of the calibration could be applied to other data obtained during the campaign, the only

  2. Why Are Hyperbolic Micrometeors No Longer Detected with the Arecibo UHF Radar ?

    Science.gov (United States)

    Meisel, D. D.; Bartlett, B. D.; Mathews, J. D.; Janches, D.; Briczinski, S.

    2004-05-01

    Micrometeor detections using the AO UHF radar have been carried out since 1997. During 1997-2000, hyperbolic (presumed extrasolar origin) orbits were obtained for about 3% of the some 30,000 detections (Meisel et al. 2003 on publicly available from the author CD-ROM and Meisel et al. Ap.J. 567, 323 2002a, Ap.J. 579,895 2002b). In one of those papers (2002a), it was predicted that Jupiter was (over the next 3 to 5 years) going to move into the predominant radiant direction of the extrasolar orbits, i.e. the local interstellar bubble. Thus it was expected that the number of extrasolar meteors would diminish. What was not expected was, however, that so far in 2001-2004 no hyperbolic orbits have been found among nearly 20,000 more orbits. At the size range of the detected micrometeors, perturbations by the major planets, solar photons as well as solar wind particle charging and magnetic field interactions must be taken into account. Thus the apparent Jovian perturbing forces (even on elliptical orbits) seems to exceed that provided by gravity alone and is likely to involve action by the extensive Jovian magnetosphere. The situation in the future promises to be even more confused because Saturn will be moving through the same radiant area even as Jupiter moves out. The micrometeor flux is continuing to be closely monitored from AO. This research is supported through NSF Planetary Astronomy and Aeronomy grants AST0205974, AST9801590, and NRA9612055007. Radar time is provided by NAIC, Arecibo Observatory operated for the National Science Foundation through a cooperative agreement with Cornell University.

  3. Arecibo Observations of Parkes Multibeam Pulsars

    Indian Academy of Sciences (India)

    N. D. R. Bhat; F. Camilo; J. M. Cordes; D. J. Nice; D. R. Lorimer; S. Chatterjee

    2002-03-01

    The on-going Parkes multibeam survey has been astoundingly successful (Manchester et al. 2001), and its discovery of over 600 pulsars has opened up new avenues for probing the Galaxy’s electron content and magnetic field. Here we report on recent observations made with the Arecibo 305-m telescope, where 80 distant, high dispersion measure pulsars (of which 35 are from the multibeam survey) were studied at multiple frequency bands in the range 0.4–2.4 GHz, in order to determine their scattering properties, rotation measures and spectral indices. The results will be used to meet a variety of science goals; viz., creating an improved model of the electron density, mapping out the Galactic magnetic field, and modeling the pulsar population.

  4. Automated UHF radar observations of meteors with aeronomic applications

    Science.gov (United States)

    Briczinski, Stanley J., Jr.

    The micrometeor observations performed using the 430 MHz Arecibo Observatory radar have been crucial for the understanding of meteoric effects on the aeronomy of the upper atmosphere. Previous techniques using the Arecibo radar required manual confirmation of each event, followed by direct measurements of the parameters (i.e. altitudes, velocities and decelerations). A new periodic FFT searching algorithm, the meteor return signal detector (MRSD) has been developed and implemented, replacing previous (labor-intensive) visual verification. The MRSD shows an improvement over traditional searching routines by increasing the event detection rate by as much as 30% as well as significantly reducing the required analysis time. The new technique used to detect meteors as well as the measured parameters obtained from this method are presented. The meteor parameters obtained from the MRSD are presented. Mass distributions are obtained from momentum considerations. Previous mass distributions have assumed a constant meteoroid mass density of 3 gm/cm3. Using statistical interpretations of the parameters obtained from the MRSD, the meteoroid mass density has been revised to a constant mass density of 1 gm/cm 3. This new mass result represents the first analysis and revision of the meteoroid mass since large aperture radars began observing meteors in the early 1990s. In some cases meteors are observed that appear to catastrophically destruct within the beam. These meteors appear to undergo minor ablation of their volatile components before annihilation---the terminal event---that occurs in under 1 ms. As with essentially all observed meteoroids, the meteoroids that disappear in a terminal event appear to experience linear decelerations before their abrupt disappearance. This non-ablative mass deposition process may play an important role in the composition of the upper atmosphere as it apparently produces sub-micron-sized particles. The first statistical analyses of the terminal

  5. Re-evaluation of the Micrometeor Mass Flux into the Earth's Atmosphere Using Arecibo UHF Radar Data.

    Science.gov (United States)

    Meisel, D. D.

    2005-12-01

    Thanks to the advanced search and analysis algorithms developed and written by S. J. Briczinski and J. D. Mathews, CSSL-Penn State, a highly homogeneous sample of nearly 20,000 events in 2001 and 2004 has been obtained and subjected to an extensive statistical analysis. Significant correlations of several dynamical parameters of decelerating particles with height have been found leading to the recovery of particle density. Previously radii were derived assuming the density was the canonical 3000 kg/m3. The density histogram can be deconvolved to compensate for inclination with the beam and possible variations of shape through a variable drag coefficient. Now that individual particle densities are available, revised radii and mass histograms have been derived. The new results and their implications for the dust component of the Earth's upper atmosphere will be discussed in detail. This effort has been supported by NSF Grant AST 02-05848 to The Pennsylvania State University and AST 02-05974 to SUNY-Geneseo The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under cooperative agreement with the National Science Foundation.

  6. Radio OH Observations of Recent Bright Comets from Arecibo

    Science.gov (United States)

    Lovell, Amy J.; Howell, Ellen S.

    2014-11-01

    We obtained OH spectra of recent comets with the Arecibo 305m radiotelescope. C/2012 X1 LINEAR was observed between 03 November 2013 and 13 January 2014, C/2014 E2 Jacques on 14 dates between 10 May and 31 July 2014, and C/2012 K1 PANSTARRS on 12 dates between 16 June and 23 August 2014. Spectra at 1667 and 1665 MHz (18cm wavelength) were obtained with an on-sky beam size of 2.9 arcminutes, mapping 7 positions of the OH within 4 arcminutes of the nucleus when the coma is sufficiently large. Radio OH spectra are seen via a Λ-doublet, with the excitation of the lines depending on the heliocentric velocity of the comet. We interpret the spectra via a Monte Carlo model, taking into account the OH inversion predictions of Despois et al. (1981) or Schleicher & A'Hearn (1988). In highly productive comets, high densities thermalize the lines, reducing the line strength near the nucleus. Models of mapping observations can directly constrain the radius within which quenching is active, and thus yield a more accurate estimate of the gas production rate, while radio observations at high spectral resolution place excellent constraints on the gas outflow velocity whether or not the coma is resolved. We present gas production rates, quenching radius estimates and outflow velocities for comets C/2012 X1 LINEAR, C/2014 E2 Jacques and C/2012 K1 PANSTARRS. Near its noteworthy sungrazing perihelion, comet C/2012 S1 ISON presented too small a gas coma for mapping observations, so we present only estimated gas production rates and outflow velocities for these unresolved observations.

  7. The Arecibo Galaxy Environment Survey: Precursor Observations of the NGC 628 group

    CERN Document Server

    Auld, R; Davies, J I; Catinella, B; Henning, P A; Linder, S; Momjian, E; Müller, E; O'Neil, K; Sabatini, S; Schneider, S; Bothun, G; Cortese, L; Disney, M; Hoffman, G L; Putman, M; Rosenberg, J L; Baes, M; De Blok, W J G; Boselli, A; Brinks, E; Brosch, N; Irwin, J; Karachentsev, I D; Kilborn, V A; Koribalski, B; Spekkens, K

    2006-01-01

    The Arecibo Galaxy Environment Survey (AGES) is one of several HI surveys utilising the new Arecibo L-band Feed Array (ALFA) fitted to the 305m radio telescope at Arecibo. The survey is specifically designed to investigate various galactic environments to higher sensitivity, higher velocity resolution and higher spatial resolution than previous fully sampled, 21 cm multibeam surveys. The emphasis is on making detailed observations of nearby objects although the large system bandwidth (100 MHz) will allow us to quantify the HI properties over a large instantaneous velocity range. In this paper we describe the survey and its goals and present the results from the precursor observations of a 5 degree x 1 degree region containing the nearby (~10 Mpc) NGC 628 group. We have detected all the group galaxies in the region including the low mass (M{HI}~10^7Mo) dwarf, dw0137+1541 (Briggs, 1986). The fluxes and velocities for these galaxies compare well with previously published data. There is no intra-group neutral gas...

  8. Observed diurnal and seasonal behavior of the micrometeor flux using the Arecibo and Jicamarca radars

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    Janches, D.; Chau, J. L.

    2005-09-01

    In this paper, we present results from meteor head-echo observations using the 430 MHz dual beam Arecibo radar in Puerto Rico and the 50 MHz Jicamarca radar in Peru. We show that the seasonal behavior reflected in the fast component of the micrometeor velocity distributions measured at Arecibo can be well explained by a micrometeor radiant distribution centered at the Earth's apex as measured by Jicamarca Radio Observatory (JRO). We conclude that these radars, as probably every other high power and large aperture radar, detect this micrometeor population that show good agreement with the so-called South and North Apex sources reported by Jones and Brown [1993. Monthly Notices of the Royal Astronomical Society]. However, these radars do not seem to detect particles from any other source reported by those authors. We also showed that in order to explain the diurnal and seasonal behavior of the meteor rate detected at Arecibo, based on the results determined by the Jicamarca radar, a strong atmospheric filtering effect must exist. This effect is produced by the early and higher ablation of micrometeors, which enter the atmosphere a low elevation angles, probably reaching high temperature at higher altitudes and depositing some or all their material before they penetrate deep into the Mesosphere/Lower Thermosphere region. These results explain at some level the missing mass inconsistency raised by the comparison of meteor fluxes derived from satellite and traditional meteor radar observations. They also may be the source of the observed high altitude ions and metallic layers observed by radars and lidars, respectively.

  9. Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity

    Science.gov (United States)

    Raizada, S.; Tepley, C. A.; Janches, D.; Friedman, J. S.; Zhou, Q.; Mathews, J. D.

    2004-04-01

    We report on the first simultaneous observations of Ca and K metallic layers using the low-latitude lidar systems located at the Arecibo Observatory in Puerto Rico (18.35°N, 66.75°W). We often observe sudden increases in both Ca and K densities during early morning hours on nights where meteor showers take place. During these periods, the Ca/K abundance ratio varied between 2 and 3. On occasion, differences were observed in Ca and K layers, which relate to differences in the chemistry of the two metals. It is known that metallic layers display distinct seasonal variations, but chemistry alone cannot explain the measured differences. Thus, we examined whether or not the seasonal distribution of micrometeoroids, derived from meteor observations using the Arecibo 430MHz radar, can account for the dissimilar metallic observations. We found that the deposition flux of micrometeoroids, with particle sizes ranging between 0.5 and 100μm, increased by a factor of two during the summer as compared with the winter, suggesting a seasonal variation of their sporadic activity. In addition, our data support the idea that differential ablation leads to a depletion of Ca atoms in the mesosphere.

  10. Statistical and fragmentation properties of the micrometeoroid flux observed at Arecibo

    Science.gov (United States)

    Briczinski, S. J.; Mathews, J. D.; Meisel, D. D.

    2009-04-01

    The micrometeor observations performed using the 430 MHz Arecibo Observatory radar have proven to be crucial for the understanding of meteoric effects on the aeronomy of the upper atmosphere. Meteors observed during the February 2001, 2006, and 2007 campaigns have been analyzed with a fast Fourier transform periodic search algorithm that automatically and uniformly detects meteor events between altitudes of 80 and 142 km. We present a description of the new technique used to detect meteors as well as the meteoroid parameters: altitude profiles, radial speeds, and decelerations. We also note the expected correlation between the radar transmitted power and the observed meteor event rate. The large number of events has enabled us to statistically estimate the average mass density of the observed population indicating that our detected events are generally cometary (1 g/cm3) and not asteroidal (3 g/cm3) in origin. Additionally, many meteor events are observed in which the radar meteor disappears from one radar pulse to the next (i.e., in 1 ms). We interpret this as indicative of the catastrophic destruction of the meteoroid. Until destruction, these events appear to undergo only minor ablation of their volatile components over the observed trajectory. As with a major fraction of all events recorded, the meteoroids that disappear in a terminal event show linear decelerations before their abrupt disappearance. This apparently low ablative mass deposition process may play an important role in the composition (aeronomy) of the upper atmosphere, as it likely produces submicron-sized particles rather than the atom level products of ablation. First results on the altitude, speed, and mass distributions of terminal event meteoroids are given yielding some clues on the physics of the terminal event. Finally, the statistics of those events that yield no deceleration are compared statistically with those that exhibit deceleration with the conclusion that both groups are

  11. Initial altitude of the micrometeor phenomenon: Comparison between Arecibo radar observations and theory

    Science.gov (United States)

    Janches, Diego; Revelle, Douglas O.

    2005-08-01

    We present calculations of the altitude at which the micrometeor phenomenon begins, that is, the point where the interaction between micrometeoroids and the Earth's atmosphere becomes important. At these altitudes, physical processes such as light emission, heating, electron production, etc., begin to occur. The calculations are performed using four very different initial height models including (1) solving the full integration of the single-body meteor equations, (2) using a balance between the loss of momentum and the component of the acceleration due to gravity along the meteor trajectory, (3) using a solution that emanates from a "linearized" form of the meteor energy equation but without including either atmosphere or meteoroid radiation emission effects, and finally (4) utilizing a solution of the meteor energy equation that is specifically approximated for small particles. We compare our evaluated theoretical results with direct micrometeor observations detected using the 430 MHz Arecibo Observatory (AO) radar system. The goal of these calculations is to provide reliable initial conditions in order to completely model the AO micrometeor observations, most of which have nearly constant decelerations. The nature of this study, although performed with already existing theoretical formulations, is of unprecedented value because it is the first study where these models are directly compared against very highly resolved micrometeor velocity and altitude distributions that are derived directly from the radar observations. We found that the meteor energy equation approximated for small particles agrees very well with the radar observations, in particular for meteor melting temperatures of the order of 2100 K and entry angles lower than 30° with respect to the radar beam normal direction. Unfortunately, from this model the composition characteristics of the particles detected by the AO radar cannot conclusively be drawn. However, comparison with the calculation of

  12. The Arecibo Galaxy Environment Survey: Observations towards the NGC 7817/7798 Galaxy Pair

    Science.gov (United States)

    Harrison, Amanda; Robert Minchin

    2016-01-01

    The Arecibo Galaxy Environment Survey (AGES) examines the environment of neutral hydrogen gas in the interstellar medium. AGES uses the 305m Arecibo Radio Telescope and the Arecibo L-Band Feed Array to create a deep field neutral hydrogen survey which we used to detect galaxies in an area five square degrees around the galaxy pair NGC 7817/7798. By finding and investigating hydrogen rich galaxies we hope to gain a better understanding of how the environment affects galaxy evolution. H1 line profiles were made for the detected H1 emission and ten galaxies which had the characteristic double-horned feature were found. NGC 7798 was not detected, but NGC 7817 and the other galaxies were cross-identified in NASA/IPAC Extragalactic Database as well as in Sloan Digital Sky Survey to obtain optical data. Out of the ten, two of the sources were uncatalogued. We analyzed the hydrogen spectra and aperture photometry to learn about the characteristics of these galaxies such as their heliocentric velocity, flux, and mass of the neutral hydrogen. Furthermore, we graphed the Tully-Fisher and the Baryonic Tully-Fisher of the ten sources and found that most followed the relation. One that is the biggest outlier is suspected be a galaxy cluster while other outliers may be caused by ram pressure stripping deforming the galaxy.

  13. Radio and Meteor Science Outcomes From Comparisons of Meteor Radar Observations at AMISR Poker Flat, Sondrestrom, and Arecibo

    Science.gov (United States)

    Mathews, J. D.; Briczinski, S. J.; Meisel, D. D.; Heinselman, C. J.

    2008-06-01

    Radio science and meteor physics issues regarding meteor “head-echo” observations with high power, large aperture (HPLA) radars, include the frequency and latitude dependency of the observed meteor altitude, speed, and deceleration distributions. We address these issues via the first ever use and analysis of meteor observations from the Poker Flat AMISR (PFISR: 449.3 MHz), Sondrestrom (SRF: 1,290 MHz), and Arecibo (AO: 430 MHz) radars. The PFISR and SRF radars are located near the Arctic Circle while AO is in the tropics. The meteors observed at each radar were detected and analyzed using the same automated FFT periodic micrometeor searching algorithm. Meteor parameters (event altitude, velocity, and deceleration distributions) from all three facilities are compared revealing a clearly defined altitude “ceiling effect” in the 1,290 MHz results relative to the 430/449.3 MHz results. This effect is even more striking in that the Arecibo and PFISR distributions are similar even though the two radars are over 2,000 times different in sensitivity and at very different latitudes, thus providing the first statistical evidence that HPLA meteor radar observations are dominated by the incident wavelength, regardless of the other radar parameters. We also offer insights into the meteoroid fragmentation and “terminal” process.

  14. Anomalous echoes observed with the EISCAT UHF radar at 100-km altitude

    Directory of Open Access Journals (Sweden)

    E. Malnes

    Full Text Available We have observed a number of strong echoes with the European incoherent-scatter (EISCAT UHF (930-MHz radar at angles 83.5° and 78.6° with the geomagnetic field and at about 100-km altitude north in the auroral zone. The echoes are short-lived and occur in single 2- or 10-s data dumps. They are offset by 125–130 kHz with respect to the transmitted frequency. In most cases the offset compares well with the frequency of gyro lines in the incoherent-scatter spectrum, as given by the standard linear dispersion relation. But sometimes the measured offsets deviate significantly from the model calculations, and the interpretation in terms of gyro lines becomes questionable. The discrepancy could possibly be explained by local deviations in the magnetic field from the model (IGRF 1987, which are generated by incoming particle beams. A more serious problem with the gyro-line theory is how the line can be excited at altitudes where the collisional damping is substantial. The high intensity and short lifetime of the signal point to a fast-growing plasma instability as the likely excitation mechanism, if the gyro-line interpretation is correct. The cause of the instability could be the same particle beams as those causing the disturbances in the magnetic field. Alternatively, the observations may be interpreted as meteor head echoes. The large Doppler shifts, the short lifetimes and the altitudes of the signals support this explanation. The main difficulty is that the distribution of measured offsets appears to be different in magnetically active conditions and in less active conditions. Also, the occurrence of echoes does not seem to follow the expected changes in meteor density. More observations in different conditions are needed to decide between the two interpretations. As it is, we are inclined to believe in the meteor head echo theory, the objections to the gyro-line theory being more fundamental.

  15. The atmospheric fate of 0.5-100 micron dust observed as radar micrometeors at Arecibo Observatory.

    Science.gov (United States)

    Mathews, J. D.; Janches, D.; Meisel, D. D.; Zhou, Q.-H.

    Radar micrometeor observations at Arecibo Observatory yield instantaneous Doppler speed and deceleration measurements that, combined with appropriate model atmosphere results, yield the ballistic parameter for many events. Assuming 3 gm/cc mass density and spherical particles, the ballistic parameter is converted to particle mass and size range. The observed size range is 0.5-100 micron radius. These measurements additionally provide daily and seasonal event rates and allow whole-earth mass flux estimates over the observable particle size distribution (Mathews et al., The micrometeor mass flux into the upper atmosphere: Arecibo results and a comparison with prior estimates, Geophysical Research Letters 28, 1929-1932, 2001). Updated mass fluxes will be presented. Further, we present information about the processes whereby the dust particles slow and disperse into the upper atmosphere. We find no evidence of simple ablation over the altitude range that these particles are observed as radar meteors. We do however find that a significant fraction of these particles catastrophically disintegrate and are likely not deposited in atomic form but rather into nanometer-sized smoke particles.

  16. Physical and orbital properties of micrometeors observed using the 430 MHz Arecibo observatory radar

    Science.gov (United States)

    Janches, Diego

    Physical and orbital properties of 1200+ radar micrometeors are deduced from more than 8000+ event detections using the 430 MHz Arecibo radar in Puerto Rico. These results are very distinct from classical HF/VHF radar observations in that the head-echo (radar scattering from the region immediately surrounding the meteoroid) is always observed, leading uniquely to very accurate Doppler speed determinations. A multi-pulse technique has been developed that permits the direct measurement of Doppler velocities from the micrometeor leading-edge (or head-echo), and in some 26% of the sample, micrometeor deceleration is also accurately measured. The results from those showing decelerations are described in some detail. The average measured micrometeor velocity is around ˜50 km/sec unlike that obtained with classical low-power VHF radars which is nearly a factor of two lower. The observed micrometeor decelerations range from a few km/sec2 to ˜1000 km/sec2. The measurements of highly resolved meteor altitudes, velocities and decelerations are crucial for understanding a number of aeronomical and astronomical problems in meteor science. One important property, the particle meteor ballistic parameter (BP)---the ratio of the meteoroid mass to cross-sectional area---gives a physical characterization of the decelerating particles independent of any assumption about meteoroid shape and mass density. The BP calculation for these micrometeors results in a distribution that covers a wide range (10-4--10 -1gm/cm2). The sizes and masses that these results represent, when the meteoroid is assumed to be a sphere of density 3 gm/cm3, are radii ˜0.5 x 10-4--2 x 10-2 cm and masses of a fraction of a nanogram to 10 mugm. An original criterion to separate particles that are travelling down-the-beam from those with a more significant across-the-beam velocity component was developed. This criterion is based on the variation of the meteor BP during the time the particles are observed by the

  17. Arecibo and Goldstone Radar Observations of the First-Recognized Binary Near-Earth Asteroid: (385186) 1994 AW1

    Science.gov (United States)

    Richardson, James E.; Taylor, Patrick A.; Rivera-Valentin, Edgard G.; Rodriguez-Ford, Linda A.; Benner, Lance A. M.; Naidu, Shantanu P.; Giorgini, Jon D.; Busch, Michael W.; Ghigo, Frank d.; Kobelski, Adam; Warner, Brian D.; Springmann, Alessondra; Marshall, Sean E.; Steckloff, Jordan K.; Sharkey, Benjamin

    2015-11-01

    Near-Earth asteroid (385186) 1994 AW1 was discovered at Palomar Observatory on 11 January 1994. Subsequent observations of this Amor family, Sa-class asteroid also identified it as the first candidate binary NEA, as indicated by multiple periodicities and possible mutual eclipsing/occulting events in the object’s lightcurve. On 15 July 2015 this asteroid made its closest approach to Earth since its discovery, coming within 0.065 AU (25 lunar distances), and prompting an extended observation campaign using both the JPL-Goldstone and Arecibo Observatory planetary radars. Goldstone observations covered the 14-19 July period of closest approach (0.066-0.070 AU) while the object remained below Arecibo’s observing horizon, with Arecibo picking up the observations between 20-30 July, as the object moved from 0.075 to 0.126 AU distance. At Goldstone, we were able to observe this object with range resolutions of 150 m using a Goldstone (DSS-14) to Green Bank Telescope (GBT) bistatic configuration, while at Arecibo, we conducted monostatic observations of 1994 AW1 using the 2380 MHz (12.6 cm) radar at resolutions of 30 m and 75 m.As a result, and twenty years after its discovery, these observations have confirmed the binary nature of 1994 AW1, showing the primary body to be about 600 m in diameter, the secondary body to be about half the diameter of the primary, with the two orbiting a common center of mass at a distance of about 1.2 km apart. Delay-Doppler image comparisons of the primary over the course of six nights (at 30 m resolution) confirm a lightcurve-derived rotation period of 2.518 +/- 0.002 hr, as >90% longitude coverage was achieved, revealing a slightly elongated, irregular surface morphology. Delay-Doppler images of the secondary reveal an elongated, irregular body which appears to be tidally locked, with its long axis pointed towards the primary as it orbits with a period of about 22 hr (also consistent with the lightcurve analysis). These very early

  18. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR

    Science.gov (United States)

    Fentzke, J. T.; Janches, D.; Sparks, J. J.

    2009-05-01

    In this work, we use a semi-empirical model of the micrometeor input function (MIF) together with meteor head-echo observations obtained with two high power and large aperture (HPLA) radars, the 430 MHz Arecibo Observatory (AO) radar in Puerto Rico (18°N, 67°W) and the 450 MHz Poker flat incoherent scatter radar (PFISR) in Alaska (65°N, 147°W), to study the seasonal and geographical dependence of the meteoric flux in the upper atmosphere. The model, recently developed by Janches et al. [2006a. Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars. Journal of Geophysical Research 111] and Fentzke and Janches [2008. A semi-empirical model of the contribution from sporadic meteoroid sources on the meteor input function observed at arecibo. Journal of Geophysical Research (Space Physics) 113 (A03304)], includes an initial mass flux that is provided by the six known meteor sources (i.e. orbital families of dust) as well as detailed modeling of meteoroid atmospheric entry and ablation physics. In addition, we use a simple ionization model to treat radar sensitivity issues by defining minimum electron volume density production thresholds required in the meteor head-echo plasma for detection. This simplified approach works well because we use observations from two radars with similar frequencies, but different sensitivities and locations. This methodology allows us to explore the initial input of particles and how it manifests in different parts of the MLT as observed by these instruments without the need to invoke more sophisticated plasma models, which are under current development. The comparisons between model predictions and radar observations show excellent agreement between diurnal, seasonal, and latitudinal variability of the detected meteor rate and radial velocity distributions, allowing us to understand how individual meteoroid populations contribute to the overall flux at a particular

  19. Comment on Airglow observations of the OI 7774 A multiplet at Arecibo during a magnetic storm by Roger G. Burnside, John W. Meriwether and James C. G. Walker

    Science.gov (United States)

    Sahai, Y.; Bittencourt, J. A.; Teixeira, N. R.

    1980-08-01

    Measurements and theoretical calculations of the 7774A and 6300A emissions for Arecibo, Puerto Rico, for May 2-3, 1976 during severe magnetic storm conditions are presented. The 6300 A observations were made with a tilting filter photometer looking at zenith, whereas the 7774A observations were made with a 1.0 m Ebert-Fastie spectrometer looking towards the west at an elevation angle of 20 deg. The theoretical calculations of the vertical column intensities of these emissions for this specific night, were performed using vertical electron density profile measurements made with the Arecibo 430 MHz radar. Their results show a reasonably good fit between experimental and theoretical 6300 A emissions. However, for the 7774A emission, there is a discrepancy between the theoretical vertical column intensities and the intensities observed looking west at 70 deg. from the zenith. Possible excitation mechanisms to explain the excess 7774A observed intensities are discussed.

  20. Radar detectability studies of slow and small zodiacal dust cloud particles. I. The case of Arecibo 430 MHz meteor head echo observations

    Energy Technology Data Exchange (ETDEWEB)

    Janches, D. [Space Weather Laboratory, Mail Code 674, GSFC/NASA, Greenbelt, MD 20771 (United States); Plane, J. M. C.; Feng, W. [School of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom); Nesvorný, D. [SouthWest Research Institute, Boulder, CO 80302 (United States); Vokrouhlický, D. [Institute of Astronomy, Charles University, Prague (Czech Republic); Nicolls, M. J., E-mail: diego.janches@nasa.gov, E-mail: j.m.c.plane@leeds.ac.uk, E-mail: w.feng@leeds.ac.uk, E-mail: davidn@boulder.swri.edu, E-mail: vokrouhl@cesnet.cz, E-mail: Michael.Nicolls@sri.com [SRI International, Menlo Park, CA 94025 (United States)

    2014-11-20

    Recent model development of the Zodiacal Dust Cloud (ZDC) argues that the incoming flux of meteoric material into the Earth's upper atmosphere is mostly undetected by radars because they cannot detect small extraterrestrial particles entering the atmosphere at low velocities due to the relatively small production of electrons. In this paper, we present a new methodology utilizing meteor head echo radar observations that aims to constrain the ZDC physical model by ground-based measurements. In particular, for this work, we focus on Arecibo 430 MHz observations since this is the most sensitive radar utilized for this type of observations to date. For this, we integrate and employ existing comprehensive models of meteoroid ablation, ionization, and radar detection to enable accurate interpretation of radar observations and show that reasonable agreement in the hourly rates is found between model predictions and Arecibo observations when (1) we invoke the lower limit of the model predicted flux (∼16 t d{sup –1}) and (2) we estimate the ionization probability of ablating metal atoms using laboratory measurements of the ionization cross sections of high-speed metal atom beams, resulting in values up to two orders of magnitude lower than the extensively utilized figure reported by Jones for low-speed meteors. However, even at this lower limit, the model overpredicts the slow portion of the Arecibo radial velocity distributions by a factor of three, suggesting that the model requires some revision.

  1. Radar detectability studies of slow and small Zodiacal Dust Cloud Particles: I. The case of Arecibo 430 MHz meteor head echo observations

    Science.gov (United States)

    Janches, D.; Plane, J.M.C.; Nesvorný, D.; Feng, W.; Vokrouhlický, D.; Nicolls, M.J.

    2016-01-01

    Recent model development of the Zodiacal Dust Cloud (ZDC) model (Nesvorný et al. 2010, 2011b) argue that the incoming flux of meteoric material into the Earth’s upper atmosphere is mostly undetected by radars because they cannot detect small extraterrestrial particles entering the atmosphere at low velocities due to the relatively small production of electrons. In this paper we present a new methodology utilizing meteor head echo radar observations that aims to constrain the ZDC physical model by ground-based measurements. In particular, for this work, we focus on Arecibo 430 MHz observations since this is the most sensitive radar utilized for this type of observations to date. For this, we integrate and employ existing comprehensive models of meteoroid ablation, ionization and radar detection to enable accurate interpretation of radar observations and show that reasonable agreement in the hourly rates is found between model predictions and Arecibo observations when: 1) we invoke the lower limit of the model predicted flux (~16 t/d) and 2) we estimate the ionization probability of ablating metal atoms using laboratory measurements of the ionization cross sections of high speed metal atom beams, resulting in values up to two orders of magnitude lower than the extensively utilized figure reported by Jones (1997) for low speeds meteors. However, even at this lower limit the model over predicts the slow portion of the Arecibo radial velocity distributions by a factor of 3, suggesting the model requires some revision.

  2. Radar detectability studies of slow and small zodiacal dust cloud particles. I. The case of Arecibo 430 MHz meteor head echo observations

    International Nuclear Information System (INIS)

    Recent model development of the Zodiacal Dust Cloud (ZDC) argues that the incoming flux of meteoric material into the Earth's upper atmosphere is mostly undetected by radars because they cannot detect small extraterrestrial particles entering the atmosphere at low velocities due to the relatively small production of electrons. In this paper, we present a new methodology utilizing meteor head echo radar observations that aims to constrain the ZDC physical model by ground-based measurements. In particular, for this work, we focus on Arecibo 430 MHz observations since this is the most sensitive radar utilized for this type of observations to date. For this, we integrate and employ existing comprehensive models of meteoroid ablation, ionization, and radar detection to enable accurate interpretation of radar observations and show that reasonable agreement in the hourly rates is found between model predictions and Arecibo observations when (1) we invoke the lower limit of the model predicted flux (∼16 t d–1) and (2) we estimate the ionization probability of ablating metal atoms using laboratory measurements of the ionization cross sections of high-speed metal atom beams, resulting in values up to two orders of magnitude lower than the extensively utilized figure reported by Jones for low-speed meteors. However, even at this lower limit, the model overpredicts the slow portion of the Arecibo radial velocity distributions by a factor of three, suggesting that the model requires some revision.

  3. Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles: I. The Case of Arecibo 430 MHz Meteor Head Echo Observations

    Science.gov (United States)

    Janches, D.; Plane, J. M. C.; Nesvorny, D.; Feng, W.; Vokrouhlicky, D.; Nicolls, M. J.

    2014-01-01

    Recent model development of the Zodiacal Dust Cloud (ZDC) model (Nesvorny et al. 2010, 2011b) argue that the incoming flux of meteoric material into the Earth's upper atmosphere is mostly undetected by radars because they cannot detect small extraterrestrial particles entering the atmosphere at low velocities due to the relatively small production of electrons. In this paper we present a new methodology utilizing meteor head echo radar observations that aims to constrain the ZDC physical model by ground-based measurements. In particular, for this work, we focus on Arecibo 430 MHz observations since this is the most sensitive radar utilized for this type of observations to date. For this, we integrate and employ existing comprehensive models of meteoroid ablation, ionization and radar detection to enable accurate interpretation of radar observations and show that reasonable agreement in the hourly rates is found between model predictions and Arecibo observations when: 1) we invoke the lower limit of the model predicted flux (approximately 16 t/d) and 2) we estimate the ionization probability of ablating metal atoms using laboratory measurements of the ionization cross sections of high speed metal atom beams, resulting in values up to two orders of magnitude lower than the extensively utilized figure reported by Jones (1997) for low speeds meteors. However, even at this lower limit the model over predicts the slow portion of the Arecibo radial velocity distributions by a factor of 3, suggesting the model requires some revision.

  4. High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. II. Low duty cycle, altitude-resolved, observations

    International Nuclear Information System (INIS)

    This is the second of two papers comprising a theoretical and observational study of new, altitude-resolved, observations at Arecibo of Langmuir turbulence induced in the ionosphere by a new, more powerful, high frequency heater operated at very low duty cycles. Altitude resolution of 150 m in incoherent scatter radar spectra is made possible by the coded-long-pulse method. Here we present the first observation at Arecibo of the well-developed parametric decay instability and the Langmuir decay instability cascade features in the Thomson scatter radar power spectrum, of the plasma line, at the unmodified matching altitudes under near-cold start conditions. The dependence of the plasma line spectra on altitude, pump power, and density scale length have been studied. The temporal growth and saturation of the spectra during heating and the decay of the spectra in the afterglow of heating has also been studied in detail. Comparisons are made here with the theoretical predictions of the companion paper I [DuBois , Phys. Plasmas 8, 791 (2001)]. From these comparisons and a comparison with recent observations at both Arecibo and Tromso, we conclude that all the predictions of modern Langmuir turbulence theory for the radar spectral signatures of the turbulence in a smooth ionosphere have now been verified

  5. Vertical velocity and turbulence aspects during Mistral events as observed by UHF wind profilers

    Directory of Open Access Journals (Sweden)

    J.-L. Caccia

    2004-11-01

    Full Text Available The general purpose of this paper is to experimentally study mesoscale dynamical aspects of the Mistral in the coastal area located at the exit of the Rhône-valley. The Mistral is a northerly low-level flow blowing in southern France along the Rhône-valley axis, located between the French Alps and the Massif Central, towards the Mediterranean Sea. The experimental data are obtained by UHF wind profilers deployed during two major field campaigns, MAP (Mesoscale Alpine Program in autumn 1999, and ESCOMPTE (Expérience sur Site pour COntraindre les Modèles de Pollution atmosphériques et de Transports d'Emission in summer 2001.

    Thanks to the use of the time evolution of the vertical profile of the horizontal wind vector, recent works have shown that the dynamics of the Mistral is highly dependent on the season because of the occurrence of specific synoptic patterns. In addition, during summer, thermal forcing leads to a combination of sea breeze with Mistral and weaker Mistral due to the enhanced friction while, during autumn, absence of convective turbulence leads to substantial acceleration as low-level jets are generated in the stably stratified planetary boundary layer. At the exit of the Rhône valley, the gap flow dynamics dominates, whereas at the lee of the Alps, the dynamics is driven by the relative contribution of "flow around" and "flow over" mechanisms, upstream of the Alps. This paper analyses vertical velocity and turbulence, i.e. turbulent dissipation rate, with data obtained by the same UHF wind profilers during the same Mistral events.

    In autumn, the motions are found to be globally and significantly subsident, which is coherent for a dry, cold and stable flow approaching the sea, and the turbulence is found to be of pure dynamical origin (wind shears and mountain/lee wave breaking, which is coherent with non-convective situations.

    A semi-empirical model of the contribution from sporadic meteoroid sources on the meteor input function in the MLT observed at Arecibo

    Science.gov (United States)

    Fentzke, Jonathan T.; Janches, Diego

    2008-03-01

    In this paper, we present a modeling and observational study of the micrometeor input function with a focus on understanding how each of the extraterrestrial sporadic meteoroid sources contributes to the observed meteoric flux in the Mesosphere and Lower Thermosphere (MLT) atmospheric region. For this purpose, we expand the model presented by Janches et al. (2006) using a Monte Carlo technique and incorporating: 1) a widely accepted global mass flux, which is divided into different proportions among the known sporadic meteoroid sources as the initial input above Earth's atmosphere; 2) contemporary knowledge on the source's velocity and radiant distributions; and 3) the full integration of the canonical meteor equations that describe the meteoroid entry and ablation physics. In addition, we constrain the initial input through a comparison of our modeled results with meteor observations obtained with the 430 MHz High Power and Large Aperture (HPLA) Arecibo radar in Puerto Rico that covers all seasons. The predicted meteor rates and velocity distributions are in excellent agreement with the observed ones without the need for any additional normalization factor. Our results indicate that although the Earth's Apex centered radiant source, which is characterized by high geocentric speeds (˜55 km/s), appears to be ˜33% of the meteoroids in the Solar System at 1 AU, it accounts for ˜60% of the meteors observed by the Arecibo HPLA radar in the atmosphere. The remaining 40% of observed meteors originate mostly from the Helion and Anti-Helion sources, with a very small, but constant during the day, contribution of the South and North Toroidal sources. These results also suggest that particles smaller than ˜10-3μg with slow velocities (<30 km/s) will not significantly ablate and never become observable meteors. The motivation of this effort is to construct a new and more precise MIF model needed for the subsequent modeling of the atmospheric phenomena related to the

  6. UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

    Science.gov (United States)

    Watkins, Brenton; Fallen, Christopher; Secan, James

    Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF

  7. Micrometeor Observations Using the Arecibo 430 MHz Radar. I. Determination of the Ballistic Parameter from Measured Doppler Velocity and Deceleration Results

    Science.gov (United States)

    Janches, D.; Mathews, J. D.; Meisel, D. D.; Zhou, Q.-H.

    2000-05-01

    We present a sample of radar meteors detected during the November 1997 Leonids shower period using the narrow-beam, high-power Arecibo Observatory 430-MHz radar. During this period ˜7700 events were detected over 73 h of observations that included six mornings. Near apex-crossing, 6-10 events per minute were observed in the ˜300-m diameter beam. From these events a total of 390 meteors are characterized by a clear linear deceleration as derived from the radial Doppler speed determined from the meteor-echo leading-edge (head-echo). We interpret our results in terms of the meteor ballistic parameter—the ratio of the meteoroid mass to cross-sectional area—yielding a physical characterization of these particles prior to any assumptions regarding meteoroid shape and mass density. In addition, we compare these measurements with the results of a numerical solution of the meteor deceleration equation and find them in good agreement. The size and dynamical mass of the meteoroids are estimated considering these particles to be spheres with densities of 3 g/cm 3. We also discuss atmospheric energy-loss mechanisms of these meteroids. We believe these are the first radar meteor decelerations detected since those ones reported by J. V. Evans (1966, J. Geophys. Res. 71, 171-188) and F. Verniani (1966, J. Geophys. Res. 71, 2749-2761; 1973, J. Geophys. Res. 78, 8429-8462) and the first ones for meteors of this size.

  8. A comparison of detection sensitivity between ALTAIR and Arecibo meteor observations: Can high power and large aperture radars detect low velocity meteor head-echoes

    Science.gov (United States)

    Janches, Diego; Close, Sigrid; Fentzke, Jonathan T.

    2008-01-01

    Meteor head-echo observations using High Power and Large Aperture (HPLA) radars have been routinely used for micrometeor studies for over a decade. The head-echo is a signal from the radar-reflective plasma region traveling with the meteoroid and its detection allows for very precise determination of instantaneous meteor altitude, velocity and deceleration. Unlike specular meteor radars (SMR), HPLA radars are diverse instruments when compared one to another. The operating frequencies range from 46 MHz to 1.29 GHz while the antenna configurations changes from 18,000 dipoles in a 300 m×300 m square array, phase arrays of dipoles to single spherical or parabolic dishes of various dimensions. Hunt et al. [Hunt, S.M., Oppenheim, M., Close, S., Brown, P.G., McKeen, F., Minardi, M., 2004. Icarus 168, 34-42] and Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi: 10.1016/j.icarus.2006.09.07] recently showed, by utilizing a head-echo plasma-based model, the presence of instrumental biases in the ALTAIR VHF radar system against detecting meteors produced by very small particles (<1 μg) moving at slow (˜20 km/s) velocities due to the low head echo radar cross-section (RCS) associated with these particles. In this paper we apply the same methodology to the Arecibo 430 MHz radar and compare the results with those presented by Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi: 10.1016/j.icarus.2006.09.07]. We show that, if the methodology applied by Hunt et al. [Hunt, S.M., Oppenheim, M., Close, S., Brown, P.G., McKeen, F., Minardi, M., 2004. Icarus 168, 34-42] and Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi: 10.1016/j.icarus.2006.09.07] is accurate, for particles at least 1 μg or heavier, while the bias may exist for the ALTAIR measurements, it does not exist in the Arecibo data due to its greater sensitivity.

  9. Simultaneous and common-volume lidar observations of K/Na layers and temperature at Arecibo Observatory (18°N, 67°W)

    Science.gov (United States)

    Yue, Xianchang; Zhou, Qihou; Yi, Fan; Friedman, Jonathan; Raizada, Shikha; Tepley, Craig

    2016-07-01

    We present the first simultaneous and common-volume observations of mesospheric K and Na densities and temperature conducted by a K Doppler lidar and a Na lidar at the Arecibo Observatory (18.35°N, 66.75°W), Puerto Rico. Measurements reported here were conducted on three nights with 9, 6, and 7 h of observations in December 2003 and January 2004. The behaviors of the Na and K layer and the temperature variations showed that the bottom edges of the Na and K layers matched one another almost exactly. Layer peak and column densities increased/decreased together with temperature for the Na layer, but not for the K layer. The correlation between temperature and density fluctuations was strongly positive at and just below the peak altitude of the nightly mean density profile but transitioned to negative several kilometers above the respective peak of either Na or K. The peak densities of the sporadic Na and K layers occurring at low altitudes did not behave in the same manner especially when the background temperature decreased. We discuss, qualitatively, the impact of dynamical and chemical effects on the behaviors of the Na and K layers. Our analysis suggests that wave-induced dynamical transport can account for the observed correlations between temperature, Na density, and K density fluctuations. Dynamical transport and wave-induced chemical transport have similar effects on the behaviors of the Na and K layers. The resulting differences in Na and K layers are qualitatively consistent with different dependences on temperature of the Na and K chemistries.

  10. Observations and modeling of UHF-band scintillation occurrence probability over the low-latitude region of China during the maximum activity of solar cycle 24

    Science.gov (United States)

    Zhang, H.; Liu, Y.; Wu, J.; Xu, T.; Sheng, D.

    2015-01-01

    The climatological characteristics of UHF-band scintillations over the low-latitude region of China were investigated by analyzing the observations recorded at three stations of our regional network of satellite-beacon-based scintillation monitoring in 2013. The three stations are Hainan (geographic 20.0° N, 110.3° E; geomagnetic 10.1° N, 177.4° W, dip 28.2°), Guangzhou (geographic 23.0° N, 113.0° E; geomagnetic 13.1° N, 174.8° W, dip 33.9°) and Kunming (geographic 25.6° N, 103.7° E; geomagnetic 15.7° N, 176.4° E, dip 39.0°), located at low latitudes of China. The variations of UHF-band scintillation occurrence with latitude, time and season are presented in detail to understand the morphology and climatology of ionospheric scintillations over the low-latitude region of China. An equinoctial asymmetry in the occurrences of scintillation and an obvious difference of the onset time of scintillations between Hainan and Kunming is noted in this data set. Subsequently, the ionosonde data are utilized to study the possible causes of the asymmetry between two equinoxes. The observations suggest that the mean critical frequency (foF2) at 20:00 LT (12:00 UT) in the autumnal equinoctial months (September and October) and the vernal equinoctial months (March and April) has a similar asymmetry. The ratio of the mean foF2 between two equinoxes is proportional to the ratio between the maximum scintillation occurrence in the autumnal equinox and in the vernal equinox. Therefore, this ratio can act as a proxy for the equinoctial asymmetry in the occurrences of scintillation over the low-latitude region of China, and can be used to model the equinoctial asymmetry in our empirical climatological model of scintillation occurrence probability (CMSOP). The CMSOP can provide the predictions of the occurrences of scintillation over the low-latitude region of China and was validated in this study.

  11. UHF RFID of People

    OpenAIRE

    Pol&#;vka, Milan; &#;vanda, Milan; Hudec, P&#;emysl

    2009-01-01

    Reliable RF identification of people in moderate 2 ? 10 m ranges must be based on electromagnetic wave coupling mechanism. Due to acceptable antenna dimensions, UHF or microwave operational frequencies must be used. At these frequencies, propagation of electromagnetic waves is influenced by several important physical phenomena, namely by interferences, shadowing or waveguide effects. Besides these, in this application, the functionality of TAG antennas can be negatively influenced by the pres...

  12. The Arecibo Remote Command Center Program

    Science.gov (United States)

    Crawford, Fronefield; Jenet, Fredrick; Siemens, Xavier; Dolch, Timothy; Stovall, Kevin

    2016-07-01

    The Arecibo Remote Command Center (ARCC) is a multi-institution research and education program that introduces undergraduates to the field of pulsar research. Specifically, the program trains students to work in small teams to operate several of the world's largest radio telescopes (both Arecibo and the Green Bank Telescope). Students conduct survey observations for the PALFA Galactic plane pulsar survey and conduct timing observations of millisecond pulsars (MSPs) for the NANOGrav search for gravitational waves using these telescopes. In addition, ARCC students search pulsar candidates generated from processed survey data in order to find both new radio MSPs and non-recycled pulsars. The ARCC program currently operates at four U.S. institutions and involves more than 50 undergraduate students each year. To date, ARCC students have discovered 64 new pulsars in this program.

  13. Investigation of inertia-gravity waves in the upper troposphere/lower stratosphere over Northern Germany observed with collocated VHF/UHF radars

    Directory of Open Access Journals (Sweden)

    A. Serafimovich

    2005-01-01

    Full Text Available A case study to investigate the properties of inertia-gravity waves in the upper troposphere/lower stratosphere has been carried out over Northern Germany during the occurrence of an upper tropospheric jet in connection with a poleward Rossby wave breaking event from 17-19 December 1999. The investigations are based on the evaluation of continuous radar measurements with the OSWIN VHF radar at Kühlungsborn (54.1 N, 11.8 E and the 482 MHz UHF wind profiler at Lindenberg (52.2 N, 14.1 E. Both radars are separated by about 265 km. Based on wavelet transformations of both data sets, the dominant vertical wavelengths of about 2-4 km for fixed times as well as the dominant observed periods of about 11 h and weaker oscillations with periods of  6 h for the altitude range between 5 and 8 km are comparable. Gravity wave parameters have been estimated at both locations separately and by a complex cross-spectral analysis of the data of both radars. The results show the appearance of dominating inertia-gravity waves with characteristic horizontal wavelengths of  300 km moving in the opposite direction than the mean background wind and a secondary less pronounced wave with a horizontal wavelength in the order of about 200 km moving with the wind. Temporal and spatial differences of the observed waves are discussed.

  14. Ionospheric modification induced by high-power HF transmitters: a potential for extended range VHF--UHF communications and plasma physics research

    International Nuclear Information System (INIS)

    When the ionized upper atmosphere of the earth is illuminated by high-power HF radio waves at appropriate frequencies, the temperature of electrons in the ionosphere can be raised substantially. In addition, radio waves with sufficient energy cause parametric instabilities that generate a spectrum of intense plasma waves. Observations of these phenomena have produced new understanding of plasma processes. One consequence of heating and plasma wave generation is that irregularities are formed in the electron distribution which are aligned with the earth's magnetic field. Because of this, a scatterer of large radar cross section is produced, which scatters HF through UHF communication signals over long distance paths, that would not otherwise be normally possible by ionospheric means. Results of radio, radar, communication, and photometric experiments that explored the characteristics of the volume of ionosphere which has been intentionally modified, temporarily, above facilities near Boulder (Platteville), Colo., and at Arecibo, Puerto Rico are summarized

  15. Wave-turbulence interactions observed in the lower stratosphere by the PROUST UHF radar and GPS radiosoundings

    Science.gov (United States)

    Bertin, F.; van Velthoven, P. F. J.; Bessemoulin, P.; Ney, R.; Massebeuf, M.

    1999-06-01

    During a coordinated campaign devoted to wave-turbulence interactions, measurements with the high vertical resolution PROUST radar and radiosounding have been performed in an upper level potential vorticity anomaly. This campaign took place during September 1996 at St Santin, France, (44° 39'N, 2° 12'E), where the radar is located. Radiosonde data reveal, along the eastern part of the nomaly, the presence of a saturated wave field, while the radar observes turbulent activity in regions of wave-induced windshears. Characteristic parameters of the a saturation mechanism determined by the radar and radiosondes are in generally good agreement with the saturation onset conditions provided by linear saturation theory. The predicted relationship between vertical wavelength, period and energy dissipation rate proposed by the saturated-cascade theory is also assessed, although the proportionality factor is smaller than foreseen. When approaching the jetstream region, modulation by the wave field of the background windshear gives rise to Kelvin-Helmholtz instabilities whose convective billows are observed by the radar.

  16. The Arecibo Observatory Space Academy

    Science.gov (United States)

    Rodriguez-Ford, Linda A.; Zambrano-Marin, Luisa; Petty, Bryan M.; Sternke, Elizabeth; Ortiz, Andrew M.; Rivera-Valentin, Edgard G.

    2015-11-01

    The Arecibo Observatory Space Academy (AOSA) is a ten (10) week pre-college research program for students in grades 9-12. Our mission is to prepare students for academic and professional careers by allowing them to receive an independent and collaborative research experience on topics related to space and aide in their individual academic and social development. Our objectives are to (1) Supplement the student’s STEM education via inquiry-based learning and indirect teaching methods, (2) Immerse students in an ESL environment, further developing their verbal and written presentation skills, and (3) To foster in every student an interest in science by exploiting their natural curiosity and knowledge in order to further develop their critical thinking and investigation skills. AOSA provides students with the opportunity to share lectures with Arecibo Observatory staff, who have expertise in various STEM fields. Each Fall and Spring semester, selected high school students, or Cadets, from all over Puerto Rico participate in this Saturday academy where they receive experience designing, proposing, and carrying out research projects related to space exploration, focusing on four fields: Physics/Astronomy, Biology, Engineering, and Sociology. Cadets get the opportunity to explore their topic of choice while practicing many of the foundations of scientific research with the goal of designing a space settlement, which they present at the NSS-NASA Ames Space Settlement Design Contest. At the end of each semester students present their research to their peers, program mentors, and Arecibo Observatory staff. Funding for this program is provided by NASA SSERVI-LPI: Center for Lunar Science and Exploration with partial support from the Angel Ramos Visitor Center through UMET and management by USRA.

  17. The Arecibo Remote Command Center: Students Doing Science

    Science.gov (United States)

    Miller, Andy; Jenet, F. A.; Rodriguez-Zermeno, A.; Stovall, K.

    2010-01-01

    The University of Texas-Brownsville (UTB) is home to the Center for Gravitational Wave Astronomy (CGWA) which is, in turn, the home of the Arecibo Remote Command Center (ARCC). The ARCC is a virtual control room where researchers and undergraduate students--with the assistance of local high school students--control in real time the Arecibo Observatory--the world's largest single dish radio telescope. This poster presents a general outline of ARCC programs and recent accomplishments. Several notable accomplishments include: 1) the direct involvement of high school students in the PALFA pulsar search project at the Arecibo Observatory; 2) ARCC Scholars (undergraduate physics majors at UTB) led observations for a significant percentage of PALFA observing runs; 3) a summer astronomy academy for local high school students was held for the fifth consecutive year; 4) a second cohort of ARCC Scholars brings to ten the number of undergraduate physics majors specializing in astrophysics at UTB; 5) two members of the second cohort of ARCC Scholars, along with four summer academy high school students, attended the Pulsar Search Collaboratory program at the Green Bank Observatory; 6) specialized astrophysics programs are being expanded into a number of local high schools to stimulate interest in astrophysics research.

  18. HI Absorbers from Arecibo Legacy Fast ALFA Survey

    Science.gov (United States)

    Wu, Z. Z.; Haynes, M. P.; Giovanelli, R.; Zhu, M.; Chen, R. R.

    2015-03-01

    We present some preliminary results of an on-going study of the HI 21-cm absorption line based on the 40% data release of the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey. Ten HI absorption candidates have been detected. Five of them are previously published in the literature, and the rest of them are new detections that need further confirmation. For those sources with no detected absorptions, we calculated the upper limits of their foreground HI column density N_{HI}. The statistical result of the N_{HI} distribution indicates that the ratio of average spin temperature to covering factor T_{s}/f for DLAs (the damped Lyα systems) might be larger than 500 K. Radio frequency interference (RFI) and standing waves are the main issues affecting the detection of HI absorption profiles. Our study can serve as the pathfinder for a large scale search of HI 21-cm absorption lines using the Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) which is an Arecibo-type radio telescope currently under construction in China. We discuss two types of observational studies of HI absorptions toward extragalactic sources using the FAST telescope.

  19. UHF RFID technologies for identification and traceability

    CERN Document Server

    Laheurte, Jean-Marc; Paret, Dominique; Loussert, Christophe

    2014-01-01

    UHF Radio Frequency Identification (RFID) is an electronic tagging technology that allows an object, place or person to be automatically identified at a distance without a direct line-of-sight using a radio wave exchange. Applications include inventory tracking, prescription medication tracking and authentication, secure automobile keys, and access control for secure facilities. This book begins with an overview of UHF RFID challenges describing the applications, markets, trades and basic technologies. It follows this by highlighting the main features distinguishing UHF (860MHz-960MHz) and HF

  1. Arecibo/Magellan Composite of Quetzalpetlatl Corona

    Science.gov (United States)

    1990-01-01

    This composite image was created by inserting approximately 70 orbits of Magellan data into an image obtained at the Arecibo, Puerto Rico radiotelescope and shows a geologically complex region in the southern hemisphere of Venus. The region is centered on 65 degrees south, 359 degrees east and is about 1500 x 1500 km (900 x 900 miles) in extent. The large oval feature in the lower half of the image is Quetzalpetlatl Corona, approximately 700 km (420 miles) in diameter. Coronae are circular to oval regions defined by an annulus of ridges and are centers for tectonic and volcanic activity. Tectonic activity is largely observed in a relatively narrow rim region, which in this image is defined by a complex lineated terrain that surrounds much of the corona. Bright and dark volcanic flows are seen throughout the corona and surrounding terrain. Small shield volcanoes, 1-20 km (0.6-12 miles) in diameter, are seen near the southern limit of the Magellan data image. Narrow linear troughs (seen in the image as bright lines) trend to the north-northwest of Quetzalpetlatl.

  2. The Arecibo Galaxy Environment Survey IX: the isolated galaxy sample

    Science.gov (United States)

    Minchin, R. F.; Auld, R.; Davies, J. I.; Karachentsev, I. D.; Keenan, O. C.; Momjian, E.; Rodriguez, R.; Taber, T.; Taylor, R.

    2016-02-01

    We have used the Arecibo L-band Feed Array (ALFA) to map three regions, each of 5 deg2, around the isolated galaxies NGC 1156, UGC 2082, and NGC 5523. In the vicinity of these galaxies we have detected two dwarf companions: one near UGC 2082, previously discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey, and one near NGC 1156, discovered by this project and reported in an earlier paper. This is significantly fewer than the 15.4^{+1.7}_{-1.5} that would be expected from the field H I mass function from ALFALFA or the 8.9 ± 1.2 expected if the H I mass function from the Local Group applied in these regions. The number of dwarf companions detected is, however, consistent with a flat or declining H I mass function as seen by a previous, shallower, H I search for companions to isolated galaxies. We attribute this difference in H I mass functions to the different environments in which they are measured. This agrees with the general observation that lower ratios of dwarf to giant galaxies are found in lower density environments.

  3. The Arecibo Remote Command Center: Involving Students in Major Astronomical Research

    Science.gov (United States)

    Miller, Andy; Rodriguez-Zermeno, A.; Jenet, F.

    2006-12-01

    At the Center for Gravitational Wave Astronomy (CGWA) at the University of Texas-Brownsville (UTB), we are developing the first Arecibo Remote Command Center (ARCC). The ARCC will be a virtual control room where researchers and students will control the world’s largest single dish radio telescope at the Arecibo observatory. Web cams at Arecibo and digital projectors in the ARCC will provide students with a visually spectacular view of the instrument as they control it. Projections of instrument readouts and monitor screens will give controllers a virtual view of what is happening at Arecibo from the ARCC in Brownsville. Students and research scientists of all levels will be working together in teams to perform actual observations and data analysis. In this talk we describe the current implementation of the ARCC project, plans for student research, prototype projects conducted by students during summer of 2006, recent achievements and successes of student participants, and future plans for the establishment of the ARCC program as an ongoing enterprise.

  4. Two Types of Compact UHF Antennas for Partial Discharge Measurement

    Institute of Scientific and Technical Information of China (English)

    JIN Zhuo-rui; SUN Cai-xin; CHENG Chang-kui; LI Jian

    2008-01-01

    To investigate the partial discharge (PD) online monitoring of transformers by ultra-high-frequency (UHF) approaches, high-qualified UHF antennas are focused on as one key technique. The size of UHF sensor used for PD UHF online monitoring in transformer is excessively large, therefore, it is not convenient for internal installation of transformer. Two types of compact UHF antennas with small sizes, a Hilbert fractal antenna and a small loop antenna are presented. PD experiments of three typically artificial insulation defects are executed and both antennas are used for PD measurement. The spectra of power via frequency of detected PD signals are analyzed and compared. The experimental results show that the Hilbert fractal antenna and small loop antenna are qualified for PD online UHF monitoring.

  5. Fast radio burst discovered in the Arecibo pulsar ALFA survey

    International Nuclear Information System (INIS)

    Recent work has exploited pulsar survey data to identify temporally isolated, millisecond-duration radio bursts with large dispersion measures (DMs). These bursts have been interpreted as arising from a population of extragalactic sources, in which case they would provide unprecedented opportunities for probing the intergalactic medium; they may also be linked to new source classes. Until now, however, all so-called fast radio bursts (FRBs) have been detected with the Parkes radio telescope and its 13-beam receiver, casting some concern about the astrophysical nature of these signals. Here we present FRB 121102, the first FRB discovery from a geographic location other than Parkes. FRB 121102 was found in the Galactic anti-center region in the 1.4 GHz Pulsar Arecibo L-band Feed Array (ALFA) survey with the Arecibo Observatory with a DM = 557.4 ± 2.0 pc cm–3, pulse width of 3.0 ± 0.5 ms, and no evidence of interstellar scattering. The observed delay of the signal arrival time with frequency agrees precisely with the expectation of dispersion through an ionized medium. Despite its low Galactic latitude (b = –0.°2), the burst has three times the maximum Galactic DM expected along this particular line of sight, suggesting an extragalactic origin. A peculiar aspect of the signal is an inverted spectrum; we interpret this as a consequence of being detected in a sidelobe of the ALFA receiver. FRB 121102's brightness, duration, and the inferred event rate are all consistent with the properties of the previously detected Parkes bursts.

  6. The Arecibo Observatory as an MST radar

    Science.gov (United States)

    Woodman, R. F.

    1983-01-01

    The radars and other systems at the Arecibo Observatory were designed and built, originally, for incoherent-scatter and radio-astronomy research. More recently, important additions have been made for planetary radar and artificial RF heating of the ionosphere. Although designed and built for a different application, these systems have shown to be very powerful tools for tropospheric, stratospheric and mesospheric research. The Observatory at present has two main radars: one at 430 and the other at 2380 MHz. In addition, 50-MHz MST radar work has been done using portable transmitters brought to the Observatory for this purpose. This capability will become permanent with the recent acquisition of a transmitter at this frequency. Furthermore, control and data processing systems have been developed to use the powerful HF transmitter and antennas of the HF-heating facility as an HF bistatic radar. A brief description of the four radars available at the Observatory is presented.

  7. The micrometeoroid mass flux into the upper atmosphere: Arecibo results and a comparison with prior estimates

    Science.gov (United States)

    Mathews, J. D.; Janches, D.; Meisel, D. D.; Zhou, Q.-H.

    Radar micrometeor observations at Arecibo Observatory have enabled direct estimates of the meteoroid mass flux into the upper atmosphere. We report mass flux determinations from November 1997/1998 observations that are based on the observed number of meteor events per day in the 300-m diameter Arecibo beam and on particle mass determinations from that fraction of all particles for which deceleration is measured. The average mass of the Arecibo micrometeoroids that manifest observable deceleration is ˜0.32/0.76 µgm/particle with a resultant annual whole-Earth mass flux of 1.6 × 106/2.7 × 106 kg/yr over the ˜10-5-10² µgm mass range for 1997/1998, respectively. The annual whole-earth mass flux per decade of particle mass is calculated and compared with that of Ceplecha et al. [1998] (3.7 × 106 kg/yr) and with that derived by Love and Brownlee [1993] (LB) from small particle impact craters on the orbital Long Duration Exposure Facility (LDEF). We also give the LDEF results as significantly modified using the Arecibo-determined average particle velocity of ˜50 km/sec—much larger than the effective value of 12 km/sec used by LB. This modification results in a net LDEF mass flux of 1.8×106 kg/yr—7% of the value we determined from reanalysis of the LB data using their original 12 km/sec mean impact speed. These results may provoke some debate.

  8. Arecibo, Puerto Rico Tsunami Forecast Grids for MOST Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Arecibo, Puerto Rico Forecast Model Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model....

  9. 47 CFR 73.4195 - Political advertising by UHF translators.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Political advertising by UHF translators. 73... SERVICES RADIO BROADCAST SERVICES Rules Applicable to All Broadcast Stations § 73.4195 Political advertising by UHF translators. See Public Notice, FCC 76936, dated October 8, 1976. 62 FCC 2d 896; 41...

  10. HI Absorption Lines Detected from the Arecibo Legacy Fast ALFA Survey Data

    Science.gov (United States)

    Zhong-zu, Wu; Martha P, Haynes; Riccardo, Giovanelli; Ming, Zhu; Ru-rong, Chen

    2015-10-01

    We present some preliminary results of an on-going study of HI 21-cm absorption lines based on the 40% survey data released by the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA). (1) Ten HI candidate absorbers have been detected. Five of them are previously published in the literature, and the rest of them are new detections that need further confirmation. (2) For those sources with no detected absorptions, we have calculated the upper limit of their foreground HI column density NHI. The statistical result of the NHI distribution indicates that the ratio Ts/f between the averaged spin temperature and coverage factor for DLAs (the damped Lyα systems) might be larger than 500 K. The radio frequency interference (RFI) and standing wave are the main factors affecting the detection of HI absorption lines, which have been analyzed and discussed as well in order to find a method of solution. Our study can serve as a pathfinder for the future large-scale search of HI 21-cm absorption lines using the Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST), which is an Arecibo-type radio telescope currently under construction in China with greatly increased sensitivity, bandwidth, and observational sky area. As prospects, we have discussed two types of observational studies of HI absorption lines toward extragalactic sources using the FAST telescope.

  11. Enhanced UHF RFID tags for drug tracing.

    Science.gov (United States)

    Catarinucci, Luca; Colella, Riccardo; De Blasi, Mario; Patrono, Luigi; Tarricone, Luciano

    2012-12-01

    Radio Frequency Identification (RFID) technology is playing a crucial role for item-level tracing systems in healthcare scenarios. The pharmaceutical supply chain is a fascinating application context, where RFID can guarantee transparency in the drug flow, supporting both suppliers and consumers against the growing counterfeiting problem. In such a context, the choice of the most adequate RFID tag, in terms of shape, frequency, size and reading range, is crucial. The potential presence of items containing materials hostile to the electromagnetic propagation exasperates the problem. In addition, the peculiarities of the different RFID-based checkpoints make even more stringent the requirements for the tag. In this work, the performance of several commercial UHF RFID tags in each step of the pharmaceutical supply chain has been evaluated, confirming the expected criticality. On such basis, a guideline for the electromagnetic design of new high-performance tags capable to overcome such criticalities has been defined. Finally, driven by such guidelines, a new enhanced tag has been designed, realized and tested. Due to patent pending issues, the antenna shape is not shown. Nevertheless, the optimal obtained results do not lose their validity. Indeed, on the one hand they demonstrate that high performance item level tracing systems can actually be implemented also in critical operating conditions. On the other hand, they encourage the tag designer to follow the identified guidelines so to realize enhanced UHF tags. PMID:22048779

  12. Interaction Between UHF Radiation and a Turbulent Plasma

    International Nuclear Information System (INIS)

    Previous work revealed an anomalously low low-frequency conductivity of plasma in the Alpha apparatus. Our purpose in this work was to determine the UHF conductivity. For the wavelengths 8 and 4 mm, we observed the passage of signals through the plasma, the thermal radiation of the plasma and, because of the plasma, the changed Q-factor of the discharge chamber which is regarded as a large volume resonator. Simultaneously the average plasma density was determined from the attenuation of the beam of hydrogen atoms passing through it. During the active discharge period, the plasma density was between 1013 and 10H cm-3, and the electron temperature 20 to 40 eV. A forcefree configuration of fields and currents existed in the discharge, and the plasma filled comparatively evenly thé discharge chamber of about 6 m3. In the decaying plasma, following the discharge current, interferometric measurements of the electron concentration agreed with density measurements that used the attenuation of an atomic beam. In the active period of the discharge, interferometric measurements were impossible because of the strong turbulence of the plasma, so the electron concentration was determined from the attenuation of the atomic beam. From the Q-value of the discharge chamber during the discharge, one can determine the absorption coefficient of the UHF signal in the plasma. If the average density is known from the attenuation of the atomic beam, it is possible to find the effective frequency of electron collisions. This may also be found from the dc conductivity of the plasma, which is determined by electrical measurements. On thecother hand, from the observed densities and electron temperatures one can calculate the frequency of electron collisions for a totally ionized hydrogen plasma. Both methods of determining experimentally the effective collision frequency gave much higher values than found by calculation. We may thus assert that there existed in our plasma an electron slowing

  13. The Arecibo Remote Command Center: Inspiring the Next Generation of Astrophysicists

    Science.gov (United States)

    Jenet, Fredrick; Miller, A.; Rodriguez-Zermeno, A.; Stovall, K.; van Straten, W.

    2007-12-01

    At the Center for Gravitational Wave Astronomy at the University of Texas-Brownsville (UTB) we have developed the first Arecibo Remote Command Center (ARCC). The ARCC is a virtual control room where researchers and students from the high school level and higher have real time control of the world's largest single dish radio telescope at the Arecibo observatory. Here we give an overview of the project and the progress made over the past year. Several notable accomplishments include 1) the direct involvement of high school students in the PALFA pulsar search project at the Arecibo Observatory; 2) the first remote observations conducted with the Parkes Observatory in New South Wales, Australia; 3) development of a web-based pulsar search interface which students have used to identify potential pulsar candidates; 4) completion of the ARCC room facility at the UTB campus, a state of the art professionally designed room that looks like the bridge of a starship; 5) building the second ARCC project at the University of Wisconsin-Milwaukee (ARCC@UWM).

  14. The Arecibo Galaxy Environment Survey V : The Virgo Cluster (I)

    CERN Document Server

    Taylor, R; Auld, R; Minchin, R F

    2012-01-01

    We present 21 cm observations of a 10 $\\times$ 2 degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 289 sources are detected over the full redshift range (-2,000 $<$ $v$$_{hel}$ $<$ + 20,000 km/s) with 95 belonging to the cluster ($v$$_{hel}$ $<$ 3,000 km/s). We combine our observations with data from the optically selected Virgo Cluster Catalogue (VCC) and the Sloan Digital Sky Survey (SDSS). Most of our detections can be clearly associated with a unique optical counterpart, and 30% of the cluster detections are new objects fainter than the VCC optical completeness limit. 7 detections may have no optical counterpart and we discuss the possible origins of these objects. 7 detections appear associated with early-type galaxies. We perform HI stacking on the HI-undetected galaxies listed in the VCC in this region and show that they must have significantly less gas than those actually detected in HI. Galaxies undetected in HI in the cluster appear to be really ...

  15. Using the SLAC VHF and UHF radio systems

    International Nuclear Information System (INIS)

    The use of the SLAC VHF and UHF Radio Systems and the Tunnel Antenna Systems as they are presently configured is described. The original radio system was built in 1966 and has grown in scope over the years. The Tunnel Antenna Systems were developed for, and first installed in, the PEP ring, and later added to other tunnels and redesigned to cover the UHF range, as well as VHF. The UHF radio system was designed and built for SLC use, and was first used in the SLC Arcs. The three radio systems will be described and the capabilities of each system will be defined

  16. The Arecibo Galaxy Environment Survey VI : The Virgo Cluster (II)

    CERN Document Server

    Taylor, R; Auld, R; Minchin, R F; Smith, R

    2012-01-01

    We present 21 cm observations of a 5 x degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 13 cluster members are detected, together with 36 objects in the background. We compare and contrast the results from this area with a larger 10 x degree region. We combine the two data sets to produce an HI mass function, which shows a higher detection rate at low masses (but finds fewer massive galaxies) than less sensitive wider-area surveys, such as ALFALFA. We find that the HI-detected galaxies are distributed differently to the non-detections, both spatially and in velocity, providing further evidence that the cluster is still assembling. We use the Tully-Fisher relation to examine the possibility of morphological evolution. We find that highly deficient galaxies, as well as some early-type galaxies, have much lower velocity widths than the Tully-Fisher relation predicts, indicating gas loss via ram pressure stripping. We also find that HI detections without optical count...

  17. The Arecibo Galaxy Environment Survey IX: The Isolated Galaxy Sample

    CERN Document Server

    Minchin, R F; Davies, J I; Karachentsev, I D; Keenan, O C; Momjian, E; Rodriguez, R; Taber, T; Taylor, R

    2015-01-01

    We have used the Arecibo L-band Feed Array to map three regions, each of 5 square degrees, around the isolated galaxies NGC 1156, UGC 2082, and NGC 5523. In the vicinity of these galaxies we have detected two dwarf companions: one near UGC 2082, previously discovered by ALFALFA, and one near NGC 1156, discovered by this project and reported in an earlier paper. This is significantly fewer than the 15.4 $^{+1.7}_{-1.5}$ that would be expected from the field HI mass function from ALFALFA or the 8.9 $\\pm$ 1.2 expected if the HI mass function from the Local Group applied in these regions. The number of dwarf companions detected is, however, consistent with a flat or declining HI mass function as seen by a previous, shallower, HI search for companions to isolated galaxies.We attribute this difference in Hi mass functions to the different environments in which they are measured. This agrees with the general observation that lower ratios of dwarf to giant galaxies are found in lower density environments.

  18. Fast Radio Burst Discovered in the Arecibo Pulsar ALFA Survey

    CERN Document Server

    Spitler, L G; Hessels, J W T; Lorimer, D R; McLaughlin, M A; Chatterjee, S; Crawford, F; Deneva, J S; Kaspi, V M; Wharton, R S; Allen, B; Bogdanov, S; Brazier, A; Camilo, F; Freire, P C C; Jenet, F A; Karako-Argaman, C; Knispel, B; Lazarus, P; Lee, K J; van Leeuwen, J; Lynch, R; Lyne, A G; Ransom, S M; Scholz, P; Siemens, X; Stairs, I H; Stovall, K; Swiggum, J K; Venkataraman, A; Zhu, W W; Aulbert, C; Fehrmann, H

    2014-01-01

    Recent work has exploited pulsar survey data to identify temporally isolated, millisecond-duration radio bursts with large dispersion measures (DMs). These bursts have been interpreted as arising from a population of extragalactic sources, in which case they would provide unprecedented opportunities for probing the intergalactic medium; they may also be linked to new source classes. Until now, however, all so-called fast radio bursts (FRBs) have been detected with the Parkes radio telescope and its 13-beam receiver, casting some concern about the astrophysical nature of these signals. Here we present FRB 121102, the first FRB discovery from a geographic location other than Parkes. FRB 121102 was found in the Galactic anti-center region in the 1.4-GHz Pulsar ALFA survey with the Arecibo Observatory with a DM = 557.4 $\\pm$ 3 pc cm$^{-3}$, pulse width of $3\\; \\pm 0.5$ ms, and no evidence of interstellar scattering. The observed delay of the signal arrival time with frequency agrees precisely with the expectation...

  19. ULTRA HIGH FREQUENCY (UHF) SATELLITE COMMUNICATIONS (SATCOM) TEST FACILITY

    Data.gov (United States)

    Federal Laboratory Consortium — UHF SATCOM Program Description: JITC has a mission requirement to support the directives of Chairman of the Joint Chiefs of Staff Instruction (CJCSI 6251.01), which...

  20. A short history of geophysical radar at Arecibo Observatory

    Directory of Open Access Journals (Sweden)

    J. D. Mathews

    2013-03-01

    Full Text Available As Arecibo Observatory (AO approaches its 50th anniversary, it is appropriate to review the many radars and ionospheric heaters that have been deployed on or near the 305 m dish and to summarize some of the innovative radar-based geophysical research that has resulted. The reasons William E. (Bill Gordon developed the 305 m Arecibo dish are well known but are briefly reviewed. The early and then more recent radar/feed designs are reviewed as geophysical uses of Arecibo have evolved and as the full potential of the dish and nearby facilities was and is being realized from HF through S-band frequencies. This history surely has some gaps and there are a few mysteries. The community is encouraged to fill these gaps and to help complete the history.

  1. Orbital Properties of the Arecibo Micrometeoroids at Earth Interception

    Science.gov (United States)

    Janches, D.; Meisel, D. D.; Mathews, J. D.

    2001-04-01

    Using the Arecibo Observatory (AO) 430-MHz Radar we have developed a Doppler technique to measure very precise micrometeor instantaneous velocities directly from the meteor head echo. In addition, a large number of the observed meteoroids show deceleration. With the velocity, the deceleration, and the assumptions of a spherical shape and a mean micrometeoroid mass density, we have obtained estimates of in-atmosphere particle sizes. The size estimate, the MSIS model atmosphere, and the measured deceleration are used to obtain the meteor extra-atmospheric speeds, assuming these particles undergo little mass-loss prior to and during the time we detect them (Janches et al. 2000b, Icarus145, 53-63). Orbital elements at 1 AU are presented and discussed. These results have not been corrected for perturbation effects such as radiation pressure, Poynting-Robertson drag, attraction by the giant planets, and photoelectric charging effects. So far, over 7700 detections obtained during November 1997 and 3500 during the November 1998 observation campaigns have been analyzed. The observing periods included the Leonids meteor shower, but none of the orbits are recently derived from it. Out of these detections, we present details of over 1500 orbits with eccentricities less than unity. These orbits show (a) a depletion of postperihelion particles with small perihelion distance, suggesting the possibility of collisional and thermal destruction, and (b) an enhancement of particles with perihelia in the zone between Mercury and Venus. Also discussed are 40 β-meteoroids (with radii less than 0.5 μm) dynamically related to the elliptical orbit population with q<0.7 AU. We interpret the latter results on the basis of Poynting-Robertson drag and the electromagnetic resonant effects proposed by G. E. Morfill and E. Grün (1979, Planet. Space Sci.27, 1269-1282). Comparison with previous data sets indicates that most of the AO micrometeoroid orbits are well randomized and that association

  2. Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

    OpenAIRE

    Janches, D.; Nolan, M. C.; Sulzer, M.

    2004-01-01

    Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in...

  3. Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

    OpenAIRE

    Janches, D.; Nolan, M. C.; Sulzer, M.

    2004-01-01

    Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam a...

  4. The new Arecibo Observatory Remote Optical Facility (AO-ROF) in Culebra Island, Puerto Rico: Current Status and Future Projects

    Science.gov (United States)

    Santos, P. T.

    2015-12-01

    The idea of establishing the Arecibo Observatory Remote Optical Facility (AO-ROF) in the island of Culebra is a solution to mitigate the ever cumulative quantity of cloud, fog, and rain that has distressed observations at the Arecibo Observatory (AO) during major optical campaigns and observations. Given Culebra Island's favorable geographical and climatological characteristics as its low elevation and geographic location, it appears to have more steady weather conditions than Arecibo, so therefore it provides more availability for optical observations. Placed on Culebra, optical instruments can observe the same thermospheric volume over AO sampled by the Incoherent Scatter Radar (ISR). This capability will become especially important during the High Frequency (HF) facility is on operation. Small and large scale irregularities created by that HF can be readily observed and tracked from the Culebra site, and simultaneous observations from AO of the same atmospheric volume will permit direct vector measurements of dynamical evolution of the irregularities. This work presents a discussion of the current status of AO-ROF facility, as well the future projects.

  5. The Size Distribution of Arecibo Interstellar Particles and Its Implications

    Science.gov (United States)

    Meisel, David D.; Janches, Diego; Mathews, John D.

    2002-11-01

    Size histograms of all Arecibo ultra-high-frequency radar micrometeors detected in 1997-1998 whose radii were measured by atmospheric drag are presented. Most can be fitted with either a lognormal function or, alternatively, one or more power-law functions. Either form is indicative of significant fragmentation. The interplanetary dust particle (IDP) histogram results are discussed and compared with those considered to be extrasolar particles, including a subset of those deemed to be true interstellar particles (ISPs). The Arecibo IDP power-law results are shown to agree well with those derived from IRAS dust bands and Long-Duration Exposure Facility cratering, thus confirming the applicability of the sample to the derivation of mass estimates. A dichotomy between size histograms of particles with preperihelion Earth encounters and those with postperihelion encounters is evidence that significant size histogram change occurs when the smallest particles, including all ISPs, pass close to the Sun, even if only once. A small sample of previously undetected Arecibo postperihelion ISPs coming from the direction of the known Ulysses gas and dust flow are shown to have a size distribution and solar system dynamical properties similar to other Arecibo ISPs and therefore can be combined with previous ISP results to obtain a more robust sample. Derived mass flux points for the Arecibo ISPs agree well (over 5 orders of magnitude of mass) with a previously derived mass flux distribution function for Ulysses/Galileo spacecraft dust. This combined spacecraft and ground-based mass flux function is then used to infer a number of interesting mass-related solar system and astrophysical quantities.

  6. Arecibo pulsar survey using ALFA. III. Precursor survey and population synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Swiggum, J. K.; Lorimer, D. R.; McLaughlin, M. A.; Bates, S. D.; Senty, T. R. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Champion, D. J.; Lazarus, P. [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany); Ransom, S. M. [NRAO, Charlottesville, VA 22903 (United States); Brazier, A.; Chatterjee, S.; Cordes, J. M. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Hessels, J. W. T. [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Nice, D. J. [Department of Physics, Lafayette College, Easton, PA 18042 (United States); Ellis, J.; Allen, B. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee WI 53211 (United States); Bhat, N. D. R. [Center for Astrophysics and Supercomputing, Swinburne University, Hawthorn, Victoria 3122 (Australia); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); and others

    2014-06-01

    The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo (32° ≲ ℓ ≲ 77° and 168° ≲ ℓ ≲ 214°) close to the Galactic plane (|b| ≲ 5°) for pulsars. The PALFA survey is sensitive to sources fainter and more distant than have previously been seen because of Arecibo's unrivaled sensitivity. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in ℓ and |b| ≲ 1°) and detected 45 pulsars. Detections included 1 known millisecond pulsar and 11 previously unknown, long-period pulsars. In the surveyed part of the sky that overlaps with the Parkes Multibeam Pulsar Survey (36° ≲ ℓ ≲ 50°), PALFA is probing deeper than the Parkes survey, with four discoveries in this region. For both Galactic millisecond and normal pulsar populations, we compare the survey's detections with simulations to model these populations and, in particular, to estimate the number of observable pulsars in the Galaxy. We place 95% confidence intervals of 82,000 to 143,000 on the number of detectable normal pulsars and 9000 to 100,000 on the number of detectable millisecond pulsars in the Galactic disk. These are consistent with previous estimates. Given the most likely population size in each case (107,000 and 15,000 for normal and millisecond pulsars, respectively), we extend survey detection simulations to predict that, when complete, the full PALFA survey should have detected 1000{sub −230}{sup +330} normal pulsars and 30{sub −20}{sup +200} millisecond pulsars. Identical estimation techniques predict that 490{sub −115}{sup +160} normal pulsars and 12{sub −5}{sup +70} millisecond pulsars would be detected by the beginning of 2014; at the time, the PALFA survey had detected 283 normal pulsars and 31 millisecond pulsars, respectively. We attribute the deficiency in normal pulsar

  7. Doppler Studies of Near-Antapex UHF Radar Micrometeors

    Science.gov (United States)

    Janches, D.; Mathews, J. D.; Meisel, D. D.; Getman, V. S.; Zhou, Q.-H.

    2000-02-01

    A "radar micrometeor" is the radar-scattering signature from the free electrons in the plasma generated by entry of a dust-sized meteoroid into the atmosphere. We report the first direct Doppler measurements, made using the Arecibo Observatory 430-MHz radar, of the so-called meteor head echo. Our observations demonstrate that this region is moving with the speed of the meteoroid as determined from the meteor head-echo altitude-time trajectory and that this radar return is distinct spatially and in velocity from the much more commonly observed trail echo. We also report the first observations of near-antapex micrometeors which are characterized by the very slow atmospheric speeds expected from low-ecliptic-inclination objects entering the atmosphere from behind Earth's orbital path. Of the 32 meteors observed during four early evening hours of observations on 10 January 1997, velocities were determined for 18 of the meteors of which 7 were at or just below Earth escape velocity (11.2 km/s). We give heliocentric orbits for the 11 meteor events with speeds greater than the escape velocity and present a detailed analysis of these orbital parameters and their possible origins. One particle was determined to be interstellar: a preliminary analysis indicates that the ecliptic coordinates of the radiant relative to the local standard of rest (LSR) (with the solar motion relative to the nearby stars removed) are λ=43.02°, β=-43.28°, V=-25.11 km/s or, in system II galactic coordinates lII=219.8°, bII=-52.4°, V=-25.1 km/s.

  8. ARECIBO PALFA SURVEY AND EINSTEIN-HOME: BINARY PULSAR DISCOVERY BY VOLUNTEER COMPUTING

    International Nuclear Information System (INIS)

    We report the discovery of the 20.7 ms binary pulsar J1952+2630, made using the distributed computing project Einstein-Home in Pulsar ALFA survey observations with the Arecibo telescope. Follow-up observations with the Arecibo telescope confirm the binary nature of the system. We obtain a circular orbital solution with an orbital period of 9.4 hr, a projected orbital radius of 2.8 lt-s, and a mass function of f = 0.15 Msun by analysis of spin period measurements. No evidence of orbital eccentricity is apparent; we set a 2σ upper limit e ∼-3. The orbital parameters suggest a massive white dwarf companion with a minimum mass of 0.95 Msun, assuming a pulsar mass of 1.4 Msun. Most likely, this pulsar belongs to the rare class of intermediate-mass binary pulsars. Future timing observations will aim to determine the parameters of this system further, measure relativistic effects, and elucidate the nature of the companion star.

  9. RF circuit design techniques for MF-UHF applications

    CERN Document Server

    Eroglu, Abdullah

    2013-01-01

    Magnetic resonance imaging, semiconductor processing, and RFID are some of the critical applications within the medium frequency (MF) to ultrahigh frequency (UHF) range that require RF designers to have a solid understanding of analytical and experimental RF techniques. Designers need to be able to design components and devices cost effectively, and integrate them with high efficiency, minimal loss, and required power. Computer-aided design (CAD) tools also play an important part in helping to reduce costs and improve accuracy through optimization. RF Circuit Design Techniques for MF-UHF Appli

  10. Arecibo Pulsar Survey Using ALFA. III. Precursor Survey and Population Synthesis

    CERN Document Server

    Swiggum, J K; McLaughlin, M A; Bates, S D; Champion, D J; Ransom, S M; Lazarus, P; Brazier, A; Hessels, J W T; Nice, D J; Ellis, J; Senty, T R; Allen, B; Bhat, N D R; Bogdanov, S; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J S; Freire, P C C; Jenet, F A; Karako-Argaman, C; Kaspi, V M; Knispel, B; Lee, K J; Van Leeuwen, J; Lynch, R; Lyne, A G; Scholz, P; Siemens, X; Stairs, I H; Stappers, B W; Stovall, K; Venkataraman, A; Zhu, W W

    2014-01-01

    The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo ($32^{\\circ}\\lesssim \\ell \\lesssim 77^{\\circ}$ and $168^{\\circ}\\lesssim \\ell \\lesssim 214^{\\circ}$) close to the Galactic plane ($|b|\\lesssim5^{\\circ}$) for pulsars. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in $\\ell$ and $|b|\\lesssim1^{\\circ}$) and detected 45 pulsars. For both Galactic millisecond and normal pulsar populations, we compare the survey's detections with simulations to model these populations and, in particular, to estimate the number of observable pulsars in the Galaxy. We place 95\\% confidence intervals of 82,000 to 143,000 on the number of detectable normal pulsars and 9,000 to 100,000 on the number of detectable millisecond pulsars in the Galactic disk. These are consistent with previous estimates. Given the most likely population size in each ca...

  11. Six New Millisecond Pulsars from Arecibo Searches of Fermi Gamma-Ray Sources

    CERN Document Server

    Cromartie, H T; Kerr, M; Deneva, J S; Ransom, S M; Ray, P S; Ferrara, E C; Michelson, P F; Wood, K S

    2016-01-01

    We have discovered six radio millisecond pulsars (MSPs) in a search with the Arecibo telescope of 34 unidentified gamma-ray sources from the Fermi Large Area Telescope (LAT) 4-year point source catalog. Among the 34 sources, we also detected two MSPs previously discovered elsewhere. Each source was observed at a center frequency of 327 MHz, typically at three epochs with individual integration times of 15 minutes. The new MSP spin periods range from 1.99 to 4.66 ms. Five of the six pulsars are in interacting compact binaries (period < 8.1 hr), while the sixth is a more typical neutron star-white dwarf binary with an 83-day orbital period. This is a higher proportion of interacting binaries than for equivalent Fermi-LAT searches elsewhere. The reason is that Arecibo's large gain afforded us the opportunity to limit integration times to 15 minutes, which significantly increased our sensitivity to these highly accelerated systems. Seventeen of the remaining 26 gamma-ray sources are still categorized as strong...

  12. ALFABURST: A realtime fast radio burst monitor for the Arecibo telescope

    CERN Document Server

    Chennamangalam, Jayanth; MacMahon, David; Armour, Wes; Cobb, Jeff; Lorimer, Duncan; Rajwade, Kaustubh; Siemion, Andrew; Werthimer, Dan; Williams, Christopher

    2015-01-01

    Fast radio bursts (FRBs) constitute an emerging class of fast radio transient whose origin continues to be a mystery. Realizing the importance of increasing coverage of the search parameter space, we have designed, built, and deployed a realtime monitor for FRBs at the 305-m Arecibo radio telescope. Named 'ALFABURST', it is a commensal instrument that is triggered whenever the 1.4 GHz seven-beam Arecibo $L$-Band Feed Array (ALFA) receiver commences operation. The ongoing commensal survey we are conducting using ALFABURST has an instantaneous field of view of 0.02 sq. deg. within the FWHM of the beams, with the realtime software configurable to use up to 300 MHz of bandwidth. We search for FRBs with dispersion measure up to 2560 cm$^{-3}$ pc and pulse widths ranging from 0.128 ms to 16.384 ms. Commissioning observations performed over the past few months have demonstrated the capability of the instrument in detecting single pulses from known pulsars. In this paper, I describe the instrument and the associated ...

  13. From VHF to UHF CMOS-MEMS Monolithically Integrated Resonators

    DEFF Research Database (Denmark)

    Teva, Jordi; Berini, Abadal Gabriel; Uranga, A.;

    2008-01-01

    This paper presents the design, fabrication and characterization of microresonators exhibiting resonance frequencies in the VHF and UHF bands, fabricated using the available layers of the standard and commercial CMOS technology, AMS-0.35mum. The resonators are released in a post-CMOS process cons...

  14. Very High Resolution Studies of Micrometeors Using the Arecibo 430 MHz Radar

    Science.gov (United States)

    Mathews, J. D.; Meisel, D. D.; Hunter, K. P.; Getman, V. S.; Zhou, Q.

    1997-03-01

    We present measured and inferred properties of a possible new class of "sporadic" micrometeors discovered during 18 January 1995 observations made using the very sensitive 430 MHz radar system located at Arecibo Observatory in Puerto Rico. Over 200 of these objects were observed in a 2-hr period near sunrise. The average speed was about 55 km/sec in a range of 45-63 km/sec. Approximately two-thirds of the observed trajectories were apparently nearly parallel with the vertical beam and occurred on the 93-102 km height interval. The observed occurrence rate of these meteor returns combined with the size the Arecibo beam points to a meteor flux corresponding—in the "classical" view—to ˜15th magnitude micrometeors. This information along with observed deceleration rates and radar scattering cross-sections of order 10 -8m 2, leads us to conclude that the majority of the meteors observed appear to be of order 1 μg in mass. The depth of atmospheric penetration and inferred perihelia, the majority of which lie mostly within the orbits of Mercury and Venus, point to compositions of dense refractory material. Retrograde orbits that lie well out of the plane of the ecliptic combined with the modeled effects of radiation pressure induced orbit decay suggest that these particles—with no obvious parent body—originated in the outer reaches of the solar system and that they may even be primordial in origin. It is suggested that most if not all of these particles are associated with the North Apex "source" of sporadic meteors reported by Jones and Brown (1993, Mon. Not. R. Astron. Soc.265, 524-532). Additionally, several possible radar scattering mechanisms are discussed, none of which seem completely satisfactory.

  15. Quantitative Comparison of a New Ab Initio Micrometeor Ablation Model with an Observationally Verifiable Standard Model

    Science.gov (United States)

    Meisel, David D.; Szasz, Csilla; Kero, Johan

    2008-06-01

    The Arecibo UHF radar is able to detect the head-echos of micron-sized meteoroids up to velocities of 75 km/s over a height range of 80 140 km. Because of their small size there are many uncertainties involved in calculating their above atmosphere properties as needed for orbit determination. An ab initio model of meteor ablation has been devised that should work over the mass range 10-16 kg to 10-7 kg, but the faint end of this range cannot be observed by any other method and so direct verification is not possible. On the other hand, the EISCAT UHF radar system detects micrometeors in the high mass part of this range and its observations can be fit to a “standard” ablation model and calibrated to optical observations (Szasz et al. 2007). In this paper, we present a preliminary comparison of the two models, one observationally confirmable. Among the features of the ab initio model that are different from the “standard” model are: (1) uses the experimentally based low pressure vaporization theory of O’Hanlon (A users’s guide to vacuum technology, 2003) for ablation, (2) uses velocity dependent functions fit from experimental data on heat transfer, luminosity and ionization efficiencies measured by Friichtenicht and Becker (NASA Special Publication 319: 53, 1973) for micron sized particles, (3) assumes a density and temperature dependence of the micrometeoroids and ablation product specific heats, (4) assumes a density and size dependent value for the thermal emissivity and (5) uses a unified synthesis of experimental data for the most important meteoroid elements and their oxides through least square fits (as functions of temperature, density, and/or melting point) of the tables of thermodynamic parameters given in Weast (CRC Handbook of Physics and Chemistry, 1984), Gray (American Institute of Physics Handbook, 1972), and Cox (Allen’s Astrophysical Quantities 2000). This utilization of mostly experimentally determined data is the main reason for

  16. Update on HI data collection from GBT, Parkes and Arecibo telescopes for the Cosmic Flows project

    CERN Document Server

    Courtois, Helene M

    2014-01-01

    Cosmic Flows is an international multi-element project with the goal to map motions of galaxies in the Local Universe. Kinematic information from observations in the radio HI line and photometry at optical or near-infrared bands are acquired to derive the large majority of distances that are obtained through the luminosity-linewidth or Tully-Fisher relation. This paper gathers additional observational radio data, frequently unpublished, retrieved from the archives of Green Bank, Parkes and Arecibo telescopes. Extracted HI profiles are consistently processed to produce linewidth measurements. Our current "All-Digital HI Catalog" contains a total of 20,343 HI spectra for 17,738 galaxies with 14,802 galaxies with accurate linewidth measurement useful for Tully-Fisher galaxy distances. This addition of 4,117 new measurements represents an augmentation of 34\\% compared to our last release.

  17. Dynamical Studies of Micrometeorites Detected at the Arecibo Observatory

    Science.gov (United States)

    Meisel, D. D.; Allen, T. S.; Getman, V. S.; Mathews, J. D.; Zhou, Q.

    1997-07-01

    A dynamical and orbital analysis of micrometeors detected with the Arecibo 430 MHz radar (and some dual frequency with 50 MHz) has been carried out which includes radiation pressure as well as perturbations by Jupiter and Saturn. Since these objects are apparently a new class of micrometeoroid (Mathews et al., Icarus, 1997), accurate orbital analysis is essential to determine their origin. The hypothesis that all of these small, dense particles originated from outside the solar system is explored in some detail. Alternatives to this view are briefly considered and will be the subject of future dynamical investigations.

  18. The Arecibo Pisces-Perseus Survey: An Undergraduate ALFALFA Team Project

    Science.gov (United States)

    O'Donoghue, Aileen A.; Koopmann, Rebecca A.; Haynes, Martha P.; Jones, Michael; Craig, David; Hallenbeck, Gregory L.; Rosenberg, Jessica L.; Venkatesan, Aparna; Undergraduate ALFALFA Team

    2016-01-01

    The Milky Way's position in an outer filament of Lanieakea affords us a striking view of the Pisces-Perseus Supercluster (PPS) arcing roughly from 22h to 4h and 0° to +50° concentrated between cz = 4,000 km/s and cz = 8,000 km/s as a "wall" parallel to the plane of the sky. It is bounded by voids both between Laniakea and PPS and beyond PPS. Within this box, the 70% ALFALFA survey has detected 4,800 galaxies within cz = 8,000 km/s. Of these, 80% have masses greater than 108 M⊙. At the distance of the PPS, galaxies with MHI ≤ 108 M⊙ are below the ALFALFA detection limit. Thus to further explore this rich diversity of galaxy environments and the adjoining voids, the Undergraduate ALFALFA Team is in the process of using the L-band Wide receiver at Arecibo Observatory for the Arecibo Pisces-Perseus Supercluster Survey (APPSS). We will observe galaxies with 108 M⊙ ≤ MHI ≤ 109 M⊙ chosen from the SDSS DR12 and GALEX catalogs. We are limiting our observations to the PPS ridge in 21h 30m to 3h 15m and 23° to 35°. Since this region lacks SDSS spectroscopy, targets have been selected using photometric criteria derived from SDSS and GALEX observations for galaxies detected by ALFALFA. The results of these observations will allow us to constrain the HI mass function along the PPS ridge. Application of the Tully-Fisher relation will allow a robust measure of the infall velocities of galaxies into the filament. This work has been supported by NSF grant AST-1211005.

  19. Artificial Ionization and UHF Radar Response Associated with HF Frequencies near Electron Gyro-Harmonics (Invited)

    Science.gov (United States)

    Watkins, B. J.; Fallen, C. T.; Secan, J. A.

    2013-12-01

    We present new results from O-mode ionospheric heating experiments at the HAARP facility in Alaska to demonstrate that the magnitude of artificial ionization production is critically dependent on the choice of HF frequency near gyro-harmonics. For O-mode heating in the lower F-region ionosphere, typically about 200 km altitude, artificial ionization enhancements are observed in the lower ionosphere (about 150 - 220 km) and also in the topside ionosphere above about 500 km. Lower ionosphere density enhancements are inferred from HF-enhanced ion and plasma-line signals observed with UHF radar. Upper ionospheric density enhancements have been observed with TEC (total electron content) experiments by monitoring satellite radio beacons where signal paths traverse the HF-modified ionosphere. Both density enhancements and corresponding upward plasma fluxes have also been observed in the upper ionosphere via in-situ satellite observations. The data presented focus mainly on observations near the third and fourth gyro-harmonics. The specific values of the height-dependent gyro-harmonics have been computed from a magnetic model of the field line through the HF heated volume. Experiments with several closely spaced HF frequencies around the gyro-harmonic frequency region show that the magnitude of the lower-ionosphere artificial ionization production maximizes for HF frequencies about 1.0 - 1.5 MHz above the gyro-harmonic frequency. The response is progressively larger as the HF frequency is increased in the frequency region near the gyro-harmonics. For HF frequencies that are initially greater than the gyro-harmonic value the UHF radar scattering cross-section is relatively small, and non-existent or very weak signals are observed; as the signal returns drop in altitude due to density enhancements the HF interaction region passes through lower altitudes where the HF frequency is less than the gyro-harmonic value, for these conditions the radar scattering cross-section is

  20. Meteor head echo altitude distributions and the height cutoff effect studied with the EISCAT HPLA UHF and VHF radars

    Directory of Open Access Journals (Sweden)

    A. Westman

    2004-04-01

    Full Text Available Meteor head echo altitude distributions have been derived from data collected with the EISCAT VHF (224MHz and UHF (930MHz high-power, large-aperture (HPLA radars. At the high-altitude end, the distributions cut off abruptly in a manner reminiscent of the trail echo height ceiling effect observed with classical meteor radars. The target dimensions are shown to be much smaller than both the VHF and the UHF probing wavelengths, but the cutoff heights for the two systems are still clearly different, the VHF cutoff being located several km above the UHF one. A single-collision meteor-atmosphere interaction model is used to demonstrate that meteors in the (1.3–7.2µg mass range will ionise such that critical electron density at 224MHz is first reached at or around the VHF cutoff altitude and critical density at 930MHz will be reached at the UHF cutoff altitude. The observed seasonal variation in the cutoff altitudes is shown to be a function of the seasonal variation of atmospheric density with altitude. Assuming that the electron density required for detection is in the order of the critical density, the abrupt altitude cutoffs can be explained as a consequence of the micrometeoroid joint size-speed distribution dropping off so fast at the large-mass, high-velocity end that above a certain altitude the number of detectable events becomes vanishingly small. Conversely, meteors at the low-mass end of the distribution will be gradually retarded such that the ionisation they generate never reaches critical density. These particles will remain unobservable.

    Key words. Radio science (instruments and techniques – Interplatery physics (interplanetary dust – General or miscellaneous (new fields

  1. Laboratory Testing of Active and Passive UHF RFID Tags

    OpenAIRE

    Kolarovszki Peter; Kolarovszká Zuzana; Perakovic Dragan; Periša Marko

    2016-01-01

    This article deals with research of laboratory testing by active and passive UHF tags and therefore mutual coexistence of active and passive RFID technology, which is a part of automatic identification and data capture. In this article we would like to describe an identification of transport unit based on passive technology and also by active technology. We would like to specify, how this technologies can work together and in which application focuses on postal and logistics. All results are ...

  2. Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo

    International Nuclear Information System (INIS)

    Two radar systems with beams intersecting in the HF-modified F region were used to simultaneously measure HF-enhanced plasma lines (HFPLs) and artificial geomagnetic field-aligned irregularities (AFAIs). The Arecibo 430-MHz radar was used for the HFPL observations, and a portable 49.92-MHz backscatter radar was deployed on the island of Guadeloupe to monitor the AFAIs. The experiment was desgined to examine the degree to which HF-induced plasma turbulence influences the development of AFAIs. When the HF beam is stepped up in power, sustained HFPLs and AFAIs are first observed at the same HF power level, indicating that ponderomotively driven instabilities may be involved in the early time development of AFAIs. As the HF power is increased, the HFPL backscatter power begins to saturate at ∼70 MW effective radiated power (ERP). However, the backscatter from AFAIs is linearly dependent on HF power, even at the highest (120 MW ERP) HF power levels available at Arecibo. This suggests that additional processes may contribute to the development of AFAIs. For example, ponderomotively driven instabilities may give rise to weak geomagnetic field-aligned irregularities that are subsequently driven unstable by processes excited near the upper hybrid resonance. It is also likely that AFAIs greatly impact the development of HF-induced plasma turbulence at late times (>1 s) following HF turn-on. Once the ionosphere is preconditioned by high-power HF modifications, AFAIs and HFPLs can be simultaneously sustained at a much lower HF power level than that needed to originally excite them. The nature of the preconditioning process is currently not well understood. New theoretical initiatives are clearly needed to guide future experimental activity in this area

  3. Streamflow Measurement Using A Riversonde Uhf Radar System

    Science.gov (United States)

    Teague, C.; Barrick, D.; Lilleboe, P.; Cheng, R.

    Initial field tests have been performed to evaluate the performance of a RiverSonde streamflow measurement system. The tests were conducted at a concrete-lined canal and a natural river in central California during June, 2000. The RiverSonde is a UHF radar operating near 350 MHz and is based on a modified SeaSonde system normally used to measure ocean surface currents in salt water using lower frequencies (5­25 MHz). The RiverSonde uses energy scattered by Bragg-resonant 0.5 m water waves and does not require any sensors in the water. Water velocity is calculated by observing the Doppler shift of the scattered radar energy and comparing that with the Doppler shift expected from resonant waves in still water. The radar has sufficient resolution to allow the estimation of a velocity profile across the width of the river. The antennas consisted of a 2-element transmitting antenna and a 3-element receiving antenna. The transmitting antenna provided broad illumination of the water surface, and MUSIC direction finding was used to determine the arrival direction of the re- flected radar energy. The transmitting and receiving antennas were placed on opposite banks to reduce the signal intensity variation across the channel. A chirp frequency sweep was used to determine range. Transmitted power was under 1 W, and the max- imum range was a few hundred meters. Range resolution was on the order of 10 m, and velocity resolution was about 2.5 cm/s. Extensive in-situ surface truth measurements were performed by personnel from the United States Geological Survey. The instruments included current meters suspended at various depths from a small boat positioned at several locations across the channel, video tracking of many floaters (tennis balls) on the water surface, an optical flow meter, and anemometer wind measurements. Typical water velocities were about 40 cm/s, and RMS velocity differences between the radar and in-situ measurements were 6­18% of the mean flow, with similar

  4. Radar investigations of near-Earth asteroids at Arecibo and Goldstone

    Science.gov (United States)

    Brozovic, M.; Nolan, M.; Benner, L.; Busch, M.; Howell, E.; Taylor, P.; Springmann, A.; Giorgini, J.; Margot, J.; Magri, C.; Sheppard, M.; Naidu, S.

    2014-07-01

    Radar observations are a powerful technique to study near-Earth asteroids (NEAs). The Arecibo and Goldstone planetary radars can provide delay-Doppler images that can directly resolve surface features such as concavities, hills, ridges, and boulders. Goldstone's 3.75-m resolution capability is invaluable when attempting to image NEAs with diameters smaller than 50 m. To date, over 430 near-Earth asteroids and 136 main-belt asteroids have been observed with radar. 80 % of the radar-detected NEAs have been observed within the last 10 years. The radar detection rate in the last three years has tripled relative to the average in the previous decade due to an increase in funding and greater scheduling flexibility. Currently, ˜400 observing hours per year at Goldstone and ˜600 observing hours per year at Arecibo are devoted to observing asteroids. We strive to observe all strong and moderately strong imaging targets, Yarkovsky drift candidates, NEOWISE targets, asteroids with very low perihelia that can be used to measure solar oblateness, and as many other detectable asteroids as resources allow. We also regularly attempt to observe any asteroid that is flagged by the Near-Earth Object Human Spaceflight Accessible Targets Study (NHATS) list (http://neo.jpl.nasa.gov/nhats/). To date, we have observed more than 60 NHATS objects at Arecibo and Goldstone. In the past three years, ˜1/3 of the detected asteroids were targets of opportunity (TOOs), some of which we observed within 24 h from when the discoveries were announced. Many TOOs are small, rapidly moving objects that are detectable by radar only within few lunar distances. Radar astrometry is particularly important for these asteroids because they are too faint to be followed for long with optical telescopes. A radar-range measurement often secures their orbit for decades or centuries, where otherwise the object would be lost and require rediscovery. In one of the extreme cases, two delay and two Doppler

  5. High-power high-frequency-induced Langmuir turbulence in the smooth ionosphere at Arecibo. I. Theoretical predictions for altitude-resolved plasma line radar spectra

    International Nuclear Information System (INIS)

    This is the first of two papers comprising a theoretical and observational study of new, altitude-resolved, observations at Arecibo of Langmuir turbulence induced in the ionosphere by a powerful high-frequency (hf) heater operated at very low duty cycles. As shown in paper II [Cheung , Phys. Plasmas 8, 802 (2001)], higher power enabled the first observation at Arecibo of the well-developed decay-cascade features in the Thomson scatter radar power spectrum at the unmodified matching altitudes. New theoretical predictions are presented here for the parameters of these observations emphasizing the altitude and pump power dependence of the radar spectra and the time dependence of the spectra from the decaying spectra following heater switch-off. Further details of the strong turbulence signatures from higher altitudes are also presented. At the lower matching altitudes the increase, with hf power, of the angular width of the well-developed decay-cascade spectrum allows these spectral features to come into the view of the Arecibo radar. The favorable comparison of the simulation predictions and observations is discussed in the second paper

  6. Using a LIDAR Vegetation Model to Predict UHF SAR Attenuation in Coniferous Forests

    Directory of Open Access Journals (Sweden)

    Alan Swanson

    2009-03-01

    Full Text Available Attenuation of radar signals by vegetation can be a problem for target detection and GPS reception, and is an important parameter in models describing vegetation backscatter. Here we first present a model describing the 3D distribution of stem and foliage structure based on small footprint scanning LIDAR data. Secondly we present a model that uses ray-tracing methodology to record detailed interactions between simulated radar beams and vegetation components. These interactions are combined over the SAR aperture and used to predict two-way attenuation of the SAR signal. Accuracy of the model is demonstrated using UHF SAR observations of large trihedral corner reflectors in coniferous forest stands. Our study showed that the model explains between 66% and 81% of the variability in observed attenuation.

  7. Ultra thin and transfer tattoo UHF RFID tags

    OpenAIRE

    John C. Batchelor; Parker, Edward A.; Ziai, Mohamed A.; Sanchez-Romaguera, Veronica; Yeates, Stephen

    2013-01-01

    This paper describes inkjet printing as a digital fabrication tool for the manufacture of RFID tags on flexible and porous substrates (i.e. paper). The RFID tag presented is a single layer, ultrathin UHF tag in the form of a transfer tattoo, [1] which evolved from ultra-thin, substrate insensitive tag designs, [2]. Operation has been demonstrated when mounted direct on the skin with initial read ranges in the region of 1m and subsequent improvements have enabled read range increases. The ...

  8. Baseband-processor for a passive UHF RFID transponder

    OpenAIRE

    Rodriguez-Rodriguez, J. A.; Delgado Restituto, Manuel; Rodríguez Vázquez, Angel

    2010-01-01

    This paper describes the design of a digital processor targeting the Class-1 Generation-2 EPC Protocol for UHF RFID transponders, and proposes different techniques for reducing its power consumption. The processor has been implemented in a 0.35μm CMOS technology process using automatic tools for both the logic synthesis and layout. Post-layout simulations confirm the fully functionality of the prototype and predict a worst-case power consumption of only 2.9μA at 1.2V supply.

  9. The Arecibo Remote Command Center: Undergraduate and High School Students Exploring Astrophysics

    Science.gov (United States)

    Miller, Andy

    2012-01-01

    The University of Texas-Brownsville (UTB) is home to the Arecibo Remote Command Center (ARCC). The ARCC is a virtual control room where researchers and undergraduate students_with the assistance of local high school students_control in real time the Arecibo Observatory_the world's largest single dish radio telescope. This poster presents a general outline of ARCC programs and recent accomplishments.

  10. Laboratory Testing of Active and Passive UHF RFID Tags

    Directory of Open Access Journals (Sweden)

    Kolarovszki Peter

    2016-06-01

    Full Text Available This article deals with research of laboratory testing by active and passive UHF tags and therefore mutual coexistence of active and passive RFID technology, which is a part of automatic identification and data capture. In this article we would like to describe an identification of transport unit based on passive technology and also by active technology. We would like to specify, how this technologies can work together and in which application focuses on postal and logistics. All results are verified by measurement in our AIDC laboratory, which is located at the University of Žilina. Our research contains different types of measurements in order to point out the possible influence of these two technologies. The results of our research bring the new point of view and indicate the ways using of UHF RFID technology in postal and logistics applications. At the end of this article is characterized the utilization of the RFID technology in postal logistics chain by using both passive and active technologies.

  11. Copper thin film for RFID UHF antenna on flexible substrate

    International Nuclear Information System (INIS)

    A process flow using photolithography and sputtering was studied for copper antenna fabrication on thin poly(ethylene terephthalate) (PET) substrate. The lift-off route was chosen for its flexibility at laboratory scale. It was clarified that the cleaning of PET is an important step that necessitates mild oxygen plasma etching. Then copper is sputter deposited after photolithographic definition of the antenna. Care is necessary since PET, as a very flexible substrate, is temperature sensitive. The temperature increase generated by the impact of deposited copper should be maintained below the glass transition temperature of the polymer to avoid detrimental deformation. dc power of 40 to 50 W was found to be the maximum possible sputtering power for commercial PET. It was found that the resistivity of the thin film is below two times the bulk resistivity of copper for a deposition pressure below 4×10−3 mbar and thickness above 450 nm. These results enable the reliable fabrication of copper RFID UHF antennae on a PET substrate for further testing of new tag designs. The present paper summarizes the effort to test new designs of antennae for RadioFrequency IDentification (RFID) Ultra High Frequency (UHF) tags, for use in various applications (e.g. object tracking and environment monitoring) in Vietnam

  12. DISCOVERY AND FOLLOW-UP OF A NEARBY GALAXY FROM THE ARECIBO ZONE OF AVOIDANCE SURVEY

    International Nuclear Information System (INIS)

    The Arecibo L-Band Feed Array Zone of Avoidance (ALFA ZOA) Survey has discovered a nearby galaxy, ALFA ZOA J1952+1428, at a heliocentric velocity of +279 km s-1. The galaxy was discovered at low Galactic latitude by 21 cm emission from neutral hydrogen (H I). We have obtained follow-up observations with the Expanded Very Large Array and the 0.9 m Southeastern Association for Research in Astronomy optical telescope. The H I distribution overlaps an uncataloged, potential optical counterpart. The H I linear size is 1.4 kpc at our adopted distance of D = 7 Mpc, but the distance estimate is uncertain as Hubble's law is unreliable at low recessional velocities. The optical counterpart has mB = 16.9 mag and B - R = 0.1 mag. These characteristics, including MHi = 107.0 Msun and LB = 107.5 Lsun, if at 7 Mpc, indicate that this galaxy is a blue compact dwarf, but this remains uncertain until further follow-up observations are complete. Optical follow-up observations are ongoing and near-infrared follow-up observations have been scheduled.

  13. Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

    Directory of Open Access Journals (Sweden)

    D. Janches

    2004-01-01

    Full Text Available Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and traditional meteor radar observations. They also may be the source of the observed high altitude ions and metalic layers observed by radars and lidars respectively.

  14. Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

    Science.gov (United States)

    Janches, D.; Nolan, M. C.; Sulzer, M.

    2004-04-01

    Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and traditional meteor radar observations. They also may be the source of the observed high altitude ions and metalic layers observed by radars and lidars respectively.

  15. Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz dual-beam radar

    Directory of Open Access Journals (Sweden)

    D. Janches

    2004-01-01

    Full Text Available Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and radar observations. They also may be the source of the observed high altitude ions and metallic layers observed by radars and lidars respectively.

  16. Arecibo Multi-Epoch HI Absorption Measurements Against Pulsars: Tiny-Scale Atomic Structure

    CERN Document Server

    Stanimirovic, S; Pei, Z; Tuttle, K; Green, J T

    2010-01-01

    We present results from multi-epoch neutral hydrogen (HI) absorption observations of six bright pulsars with the Arecibo telescope. Moving through the interstellar medium (ISM) with transverse velocities of 10--150 AU/yr, these pulsars have swept across 1--200 AU over the course of our experiment, allowing us to probe the existence and properties of the tiny scale atomic structure (TSAS) in the cold neutral medium (CNM). While most of the observed pulsars show no significant change in their HI absorption spectra, we have identified at least two clear TSAS-induced opacity variations in the direction of B1929+10. These observations require strong spatial inhomogeneities in either the TSAS clouds' physical properties themselves or else in the clouds' galactic distribution. While TSAS is occasionally detected on spatial scales down to 10 AU, it is too rare to be characterized by a spectrum of turbulent CNM fluctuations on scales of 10-1000 AU, as previously suggested by some work. In the direction of B1929+10, an...

  17. ARECIBO MULTI-EPOCH H I ABSORPTION MEASUREMENTS AGAINST PULSARS: TINY-SCALE ATOMIC STRUCTURE

    International Nuclear Information System (INIS)

    We present results from multi-epoch neutral hydrogen (H I) absorption observations of six bright pulsars with the Arecibo telescope. Moving through the interstellar medium (ISM) with transverse velocities of 10-150 AU yr-1, these pulsars have swept across 1-200 AU over the course of our experiment, allowing us to probe the existence and properties of the tiny-scale atomic structure (TSAS) in the cold neutral medium (CNM). While most of the observed pulsars show no significant change in their H I absorption spectra, we have identified at least two clear TSAS-induced opacity variations in the direction of B1929+10. These observations require strong spatial inhomogeneities in either the TSAS clouds' physical properties themselves or else in the clouds' galactic distribution. While TSAS is occasionally detected on spatial scales down to 10 AU, it is too rare to be characterized by a spectrum of turbulent CNM fluctuations on scales of 101-103 AU, as previously suggested by some work. In the direction of B1929+10, an apparent correlation between TSAS and interstellar clouds inside the warm Local Bubble (LB) indicates that TSAS may be tracing the fragmentation of the LB wall via hydrodynamic instabilities. While similar fragmentation events occur frequently throughout the ISM, the warm medium surrounding these cold cloudlets induces a natural selection effect wherein small TSAS clouds evaporate quickly and are rare, while large clouds survive longer and become a general property of the ISM.

  18. The Arecibo Fast Radio Burst: Dense Circum-burst Medium

    CERN Document Server

    Kulkarni, S R; Neill, J D

    2015-01-01

    The nature of fast radio bursts (FRB) has been extensively debated. Here we investigate FRB121102, detected at Arecibo telescope and remarkable for its unusually large spectral index. After extensive study we conclude that the spectral index is caused by a nebula with free-free absorption. We find that putative nebula must lie beyond the Milky Way. We conclude that FRBs are of extra-galactic origin and that they arise in dense star-forming regions. The challenge with extra-galactic models is the the high volumetric rate of FRBs. This high rate allows us to eliminate all models of catastrophic stellar deaths. Hyper-giant flares from young magnetars emerge as the most likely progenitors. Some of the consequences are: (i) Intergalactic FRB models can be safely ignored. (ii) The rich ISM environment of young magnetars can result in significant contribution to DM, Rotation Measure (RM) and in some cases to significant free-free optical depth. (iii) The star-forming regions in the host galaxies can contribute signi...

  19. UHF FM receiver having improved frequency stability and low RFI emission

    Science.gov (United States)

    Lupinetti, Francesco

    1990-02-27

    A UHF receiver which converts UHF modulated carrier signals to baseband video signals without any heterodyne or frequency conversion stages. A bandpass filter having a fixed frequency first filters the signals. A low noise amplifier amplifies the filtered signal and applies the signal through further amplification stages to a limited FM demodulator circuit. The UHF signal is directly converted to a baseband video signal. The baseband video signal is clamped by a clamping circuit before driving a monitor. Frequency stability for the receivers is at a theoretical maximum, and interference to adjacent receivers is eliminated due to the absence of a local oscillator.

  20. An active UHF RFID localization system for fawn saving

    Science.gov (United States)

    Eberhardt, M.; Lehner, M.; Ascher, A.; Allwang, M.; Biebl, E. M.

    2015-11-01

    We present a localization concept for active UHF RFID transponders which enables mowing machine drivers to detect and localize marked fawns. The whole system design and experimental results with transponders located near the ground in random orientations in a meadow area are shown. The communication flow between reader and transponders is realized as a dynamic master-slave concept. Multiple marked fawns will be localized by processing detected transponders sequentially. With an eight-channel-receiver with integrated calibration method one can estimate the direction-of-arrival by measuring the phases of the transponder signals up to a range of 50 m in all directions. For further troubleshooting array manifolds have been measured. An additional hand-held receiver with a two-channel receiver allows a guided approaching search without endangering the fawn by the mowing machine.

  1. The French PROUST UHF ST radar: new developments

    Science.gov (United States)

    Ney, R.; Delage, D.; Gabison, A.; Bertin, F.; Cremieu, A.

    1993-08-01

    The PROUST is a vertically pointed UHF (961 MHz) radar. Its range resolution is 30 meters when operating in the pulse compression mode. It has been used for many years with a 4.5 kW peak power and a processing unit yielding 32 Doppler spectrum on line. In order to increase the useful range, a 40 kW peak power amplifier cavity has been constructed. A new powerful processing unit is under development: the aim is to completely process on line 640 30 m range gates in order to obtain the first three moments of the detected peaks from the Doppler spectrum. This paper presents the new features of the radar.

  2. The Arecibo Galaxy Environments survey IV: the NGC7448 region and the HI mass function

    CERN Document Server

    Davies, J I; Burns, L; Minchin, R; Momjian, E; Schneider, S; Smith, M; Taylor, R; van Driel, W

    2011-01-01

    In this paper we describe results from the Arecibo Galaxy Environments Survey (AGES). The survey reaches column densities of ~3x10^18 cm^-2 and masses of ~10^7 M_O, over individual regions of order 10 sq deg in size, out to a maximum velocity of 18,000 km s^-1. Each surveyed region is centred on a nearby galaxy, group or cluster, in this instance the NGC7448 group. Galaxy interactions in the NGC7448 group reveal themselves through the identification of tidal tails and bridges. We find ~2.5 times more atomic gas in the inter-galactic medium than in the group galaxies. We identify five new dwarf galaxies, two of which appear to be members of the NGC7448 group. This is too few, by roughly an order of magnitude, dwarf galaxies to reconcile observation with theoretical predictions of galaxy formation models. If they had observed this region of sky previous wide area blind HI surveys, HIPASS and ALFALFA, would have detected only 5% and 43% respectively of the galaxies we detect, missing a large fraction of the atom...

  3. The Arecibo Galaxy Environment Survey X: The Structure of Halo Gas Around M33

    CERN Document Server

    Keenan, Olivia; Taylor, Rhys; Minchin, Robert

    2015-01-01

    As part of the HI Arecibo Galaxy Environments Survey (AGES) we have observed 5$\\times$4 degrees of sky centred on M33, reaching a limiting column density of $\\sim 1.5 \\times 10^{17}$ cm$^{-2}$ (line width of 10 km s$^{-1}$ and resolution 3.5\\arcmin). We particularly investigate the absence of optically detected dwarf galaxies around M33, something that is contrary to galaxy formation models. We identify 22 discrete HI clouds, 11 of which are new detections. The number of objects detected and their internal velocity dispersion distribution is consistent with expectations from standard galaxy formation models. However, the issue remains open as to whether the observed velocity dispersions can be used as a measure of the HI clouds total mass i.e. are the velocities indicative of virialised structures or have they been influenced by tidal interactions with other structures in the Local Group? We identify one particularly interesting HI cloud, AGESM33-31, that has many of the characteristics of HI distributed in t...

  4. The Second Arecibo Search for 5 GHz Radio Flares from Ultracool Dwarfs

    CERN Document Server

    Route, Matthew

    2016-01-01

    We describe our second installment of the 4.75 GHz survey of ultracool dwarfs (UCDs) conducted with the Arecibo radio telescope, which has observed 27 such objects and resulted in the detection of sporadic flaring from the T6 dwarf, WISEPC J112254.73+255021.5. We also present follow up observations of the first radio-emitting T dwarf, 2MASS J10475385+2124234, a tentatively identified radio emitting L1 dwarf, 2MASS J1439284+192915, and the known radio-flaring source, 2MASS J13142039+132011 AB. Our new data indicate that 2MASS J1439284+192915 is not a radio flaring source. The overall detection rate of our unbiased survey for radio-flaring UCDs is ~5% for new sources, with a detection rate for each spectral class of ~5-10%. Evidently, radio luminosity of the UCDs does not appear to monotonically decline with spectral type from M7 dwarfs to giant planets, in contradiction to theories of the magnetic field generation and internal structure of these objects. Along with other, recently published results, our data e...

  5. The Design and Implementation of Black Tea Traceability System Based on UHF RFID

    OpenAIRE

    Ling, Caijin; Liu, Jinxin; Wu, Jiayao; Wang, Qiushuang; Liu, Shumei; Chen, Haiqiang; Zhao, Chaoyi

    2014-01-01

    In order to realize the whole process of consumer-producer bidirectional traceability and distinguish the true from the false, according to Yinghong 9, planting, processing and circulation situation, we introduce UHF RFID and Network information technology, to design and develop the UHF RFID black tea traceability system. The system adopts .NET technology, uses Microsoft Visual Studio 2010 + VB.NET, Microsoft SQL SERVER 2005, T-SQL language for development and design, and uses the network arc...

  6. THE 5 GHz ARECIBO SEARCH FOR RADIO FLARES FROM ULTRACOOL DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Route, Matthew; Wolszczan, Alexander, E-mail: mroute@astro.psu.edu, E-mail: alex@astro.psu.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2013-08-10

    We present the results of a 4.75 GHz survey of 33 brown dwarfs and one young exoplanetary system for flaring radio emission, conducted with the 305 m Arecibo radio telescope. The goal of this program was to detect and characterize the magnetic fields of objects cooler than spectral type L3.5, the coolest brown dwarf detected prior to our survey. We have also attempted to detect flaring radio emission from the HR 8799 planetary system, guided by theoretical work indicating that hot, massive exoplanets may have strong magnetic fields capable of generating radio emission at GHz frequencies. We have detected and confirmed radio flares from the T6.5 dwarf 2MASS J10475385+2124234. This detection dramatically extends the temperature range over which brown dwarfs appear to be at least sporadic radio-emitters, from 1900 K (L3.5) down to 900 K (T6.5). It also demonstrates that the utility of radio detection as a unique tool to study the magnetic fields of substellar objects extends to the coolest dwarfs, and, plausibly to hot, massive exoplanets. We have also identified a single, 3.6{sigma} flare from the L1 dwarf, 2MASS J1439284+192915. This detection is tentative and requires confirmation by additional monitoring observations.

  7. Update on H I data collection from Green Bank, Parkes and Arecibo telescopes for the Cosmic Flows project

    Science.gov (United States)

    Courtois, Hélène M.; Tully, R. Brent

    2015-02-01

    Cosmic Flows is an international multi-element project with the goal to map motions of galaxies in the local Universe. Kinematic information from observations in the radio H I line and photometry at optical or near-infrared bands are acquired to derive the large majority of distances that are obtained through the luminosity-linewidth or Tully-Fisher relation. This paper gathers additional observational radio data, frequently unpublished, retrieved from the archives of Green Bank, Parkes and Arecibo telescopes. Extracted H I profiles are consistently processed to produce linewidth measurements. Our current `All-Digital H I Catalog' contains a total of 20 343 H I spectra for 17 738 galaxies with 14 802 galaxies with accurate linewidth measurement useful for Tully-Fisher galaxy distances. This addition of 4117 new measurements represents an augmentation of 34 per cent compared to our last release.

  8. Seasonal dependence of MSTIDs obtained from 630.0 nm airglow imaging at Arecibo

    Science.gov (United States)

    Martinis, C.; Baumgardner, J.; Wroten, J.; Mendillo, M.

    2010-06-01

    All-sky imaging data of 630.0 nm airglow emissions are used to study the seasonal and solar activity dependence of medium-scale traveling ionospheric disturbances (MSTIDs) over Arecibo, Puerto Rico (18.3° N, 66.7° W, 28° N mag lat). MSTIDs are typical F-region signatures at midlatitudes, yet limited statistical results in the American sector hindered the progress in our understanding of these dynamical structures. This study compiles data from 2002 to 2007 and shows for the first time that optically-determined MSTIDs at Arecibo present a semiannual pattern with peak occurrence at both solstices. In the Japanese longitude sector, a similar pattern has been found, but one with a main peak during local summer. This paper explains the high occurrence rate during local winter at Arecibo via E-layer/F-layer coupling and inter-hemispheric coupling, thus accounting for a consistent morphology between the two longitude sectors.

  9. The Arecibo Remote Command Center: Undergraduates and High School Students Exploring Astrophysics

    Science.gov (United States)

    Miller, Andy; Jenet, F.; Price, R. H.; Rodriguez-Zermeno, A.; Creighton, T. D.; Benacquista, M.; Guerrero-miller, A.; Romano, J. D.; Quetschke, V.

    2013-01-01

    The University of Texas-Brownsville (UTB) is home to the Arecibo Remote Command Center (ARCC). The ARCC is a virtual control room where researchers and undergraduate students—and local high school students—control in real time the Arecibo Observatory—the world’s largest single dish radio telescope. This poster presents a general outline of ARCC programs and recent accomplishments—including pulsar discoveries, construction of our own telescope array named the Low Frequency All Sky Monitor (LoFASM), the graduation of our first cohort of ARCC Scholars, and the establishment of the Center for Advanced Radio Astronomy (CARA).

  10. Tecnologia radio cognitiva en la banda ultra high frequency (UHF

    Directory of Open Access Journals (Sweden)

    Hernán Paz Penagos

    2014-01-01

    Full Text Available Mobile cellular communication companies in Colombia require more spectrum resources to expand their portfolio of services. However, additional frequency bands for that particular purpose are scarce, yet it is well known that there are many underutilized licensed bands. Therefore new radio technologies are being studied in order to solve this problem, e.g. Software Defined Radio SDR Cognitive Radio CR and Dynamic Spectrum Access DSA. These strategies recommend mobility across the radio spectrum to meet various needs and achieve greater efficiency when managing such a scarce resource. In this context, a case study is presented in an attempt to examine the require¬ments that must be met for the implementation of cognitive radio networks in Bogota. The case study includes evaluation for the possibility of migration from cellular communications to cognitive radio since the bands assigned to UltraHigh Frequency UHF television offer possible free-of-interference coexistence between the two services (i.e. Cellular and TV. The study shows feasibility to migration; however, the implementations of cognitive radio need availability of hardware, software and flexible radio platforms.

  11. Fast synchronization model for UHF spread-spectrum communication system

    Science.gov (United States)

    Skaug, R.; Olaisen, H.

    1984-10-01

    Communication systems employing wideband digital techniques and special modulation methods are presently being developed to support the requirements for speed and volume as well as survivability and efficiency in tactical battlefield data distribution. The transport of information in a battlefield scenario presents considerable problems where both the laws of physics and enemy and own actions are limiting factors. Introduction of spread spectrum equipment able to withstand the electronic warfare threat has often been impracticable in tactical systems with push-to-talk signalling. One of the reasons has been synchronization difficulties. Rapid and effective synchronization of spread spectrum systems often requires matched filter processing in the receiver. The realization of such filters presents technological problems for high data speeds. Surface acoustic wave (SAW) technology has, however, been very promising in this connection. A spread spectrum modem utilizing state of the art SAW technology to process the communication signals is discussed. The system operating at UHF is optimized for push-to-talk operation with a synchronization time of 20 microsec and offers data speeds up to 100 kbit/sec. With a processing gain of approximately 30 dB, the radio modem is also able to resolve and reject multipaths on the order of 10 nsec. It is thus expected to avoid certain selective effects due to multipath which are usually encountered in narrowband communication systems.

  12. Finishing and Commissioning the New Arecibo HF Facility

    Science.gov (United States)

    Sulzer, M. P.; Gonzalez, S. A.

    2011-12-01

    The imminent completion of the major tasks in the construction of the New Arecibo HF facility means that we must verify that the components are working as intended. The antenna system and the transmitters must be separately commissioned before they can be connected together so that we an be sure it will provide 83 dbW at 8.175 MHz, and 80 dbW at 5.1 MHz. The antenna system will be ready for initial testing in September. It Illuminates the 305 meter dish using dipoles near the surface of the dish transmitting upward to a wire mesh sub-reflector. There are three crossed dipoles for each of the two frequencies. The dipoles are supported on towers mounted on concrete pads underneath the dish. Each dipole element is connected to a transmitter through a three inch coax line. The tower foundations are nearly complete, and the towers will be erected in early September, and we expect to have at least one crossed dipole in place for initial testing by the end of September. We will need to make some measurements on the antenna system to ensure that it meets our requirements. One requirement is to match the antenna impedance to the transmission line and the transmitter closely enough to meet the transmitter specifications, the closer, the better. We have additional requirements; for example, it is necessary for efficient use of the facility that the polarization be close to circular. In most experiments, we want O mode excitation. If we were to transmit linear only half the power would reach the reflection height. The symmetry of the system assures that most of the conditions for achieving accurate circular polarization are met, but one condition is not: that exciting the transmitters driving the orthogonal elements at 90 degrees assures 90 degree separation in the corresponding antenna currents. One of the dipoles of each pair points toward the center of the array. If we think of the three crossed dipoles as consisting of a reference and two that are excited relative to it

  13. HF RFID versus UHF RFID--Technology for Library Service Transformation at City University of Hong Kong

    Science.gov (United States)

    Ching, Steve H.; Tai, Alice

    2009-01-01

    Since libraries first used RFID systems in the late 1990s, more and more libraries have identified the advantages of the technology. With advances in HF and UHF RFID, both alternatives are now viable in library applications. While some librarians are still skeptical towards UHF RFID as unproven in the library arena, the City University of Hong…

  14. Modeling and analysis of power extraction circuits for passive UHF RFID applications

    International Nuclear Information System (INIS)

    Modeling and analysis of far field power extraction circuits for passive UHF RF identification (RFID) applications are presented. A mathematical model is derived to predict the complex nonlinear performance of UHF voltage multiplier using Schottky diodes. To reduce the complexity of the proposed model, a simple linear approximation for Schottky diode is introduced. Measurement results show considerable agreement with the values calculated by the proposed model. With the derived model, optimization on stage number for voltage multiplier to achieve maximum power conversion efficiency is discussed. Furthermore, according to the Bode-Fano criterion and the proposed model, a limitation on maximum power up range for passive UHF RFID power extraction circuits is also studied.

  15. Modeling and analysis of power extraction circuits for passive UHF RFID applications

    Energy Technology Data Exchange (ETDEWEB)

    Fan Bo; Dai Yujie; Zhang Xiaoxing; Lue Yingjie, E-mail: afan_80@mail.nankai.edu.c [Institute of Microelectronics, Nankai University, Tianjin 300071 (China)

    2009-01-15

    Modeling and analysis of far field power extraction circuits for passive UHF RF identification (RFID) applications are presented. A mathematical model is derived to predict the complex nonlinear performance of UHF voltage multiplier using Schottky diodes. To reduce the complexity of the proposed model, a simple linear approximation for Schottky diode is introduced. Measurement results show considerable agreement with the values calculated by the proposed model. With the derived model, optimization on stage number for voltage multiplier to achieve maximum power conversion efficiency is discussed. Furthermore, according to the Bode-Fano criterion and the proposed model, a limitation on maximum power up range for passive UHF RFID power extraction circuits is also studied.

  16. High Latitude Scintillation Monitoring at UHF with the COMMX Experiment on TACSat4

    Science.gov (United States)

    Bernhardt, P. A.; Siefring, C. L.; Akins, K.; Nurnberger, M.

    2013-12-01

    UHF Beacon Transmissions at 253 MHz have provided high latitude scintillation monitoring from Gakona Alaska using the COMMX instrument on TACSat4. TACSat4 was constructed by the Naval Research Laboratory and was launched in September 2011 as an experimental communications satellite. Ground UHF transmissions are uplinked to TACSat4 using the 4 meter diameter antenna deployed to view the earth. These signals are coherently translated to other UHF frequency to be rebroadcast to the ground. Scintillation monitoring is achieved by taking the 401.25 MHz signals from ground DORIS beacons located in Cold Bay, Alaska; Yellowknife, Canada; Kauai, Hawaii; and Soccoro Island, Mexico. These signals are translated to 253 MHz and broadcast with the 4 meter antenna pointed to the UHF receiver located at Gakona, Alaska. The satellite antenna gain is 18 dB in this UHF band and the transmitter power is 2 Watts. The satellite is in an elliptical orbit with an inclination of 63 degrees and a perigee of 12,000 km. Doppler frequency shifts allow separation of each uplink from the ground DORIS beacons. This new scintillation monitoring system has been used to detect natural and artificial field aligned irregularity effects on the amplitude and phase of UHF carriers where typical scintillation amplitudes are 2dB or less. Using the HAARP transmitter in Alaska, TACSat4 was used to discover the artificial ionization clouds produce scintillation with as much as 16 dB and amplitude indices S4 greater than unity. This is the first demonstration of significant effects on radio scintillations using high power HF radio waves to disturb the ionosphere.

  17. Endomorphisms of On which preserve the canonical UHF-subalgebra

    DEFF Research Database (Denmark)

    Conti, Roberto; Rørdam, Mikael; Szymanski, Wojciech

    2009-01-01

    Unital endomorphisms of the Cuntz algebra On which preserve the canonical UHF-subalgebra Fn are investigated. We give examples of such endomorphisms λ=λu for which the associated unitary element u in On (which satisfies λ(Sj)=uSj for all j) does not belong to Fn. One such example, in the case when...... n=2, arises from a construction of a unital endomorphism of O2 which preserves the canonical UHF-subalgebra and where the relative commutant of its image in O2 contains a copy of O2. Udgivelsesdato: 1 August...

  18. Use of high-thermal conductive aluminum nitride based ceramics in vacuum UHF electronic devices

    Directory of Open Access Journals (Sweden)

    Chasnyk V. I.

    2013-06-01

    Full Text Available Analysis of properties and characteristics of the alumina, beryllium oxide and aluminum nitride based ceramic materials used in UHF electronic devices has been made. It was shown that the complex of parameters including structural and functional characteristics of the high-thermal conductive aluminum nitride ceramics prevail over all types of alumina ceramics and is not lower than the same characteristics of the beryllium oxide ceramics especially at the temperatures higher than 450 °C. The examples of the prevailing use of the aluminum nitride ceramics inside vacuum UHF-region devices: TWT’s and klystrons.

  19. Compact broadband circularly polarised slot antenna for universal UHF RFID readers

    DEFF Research Database (Denmark)

    Xu, Bo; Zhang, Shuai; Liu, Yusha;

    2015-01-01

    A compact broadband circularly polarised (CP) slot antenna is designed for universal ultra-high-frequency (UHF) radio frequency identification (RFID) readers. The antenna consists of an L-shaped metal strip and a square-slot-loaded ground plane with four tuning stubs. The total size is 100 mm×100mm......×1.6 mm. The measured –10 dB impedance bandwidth is 40.7% (772–1166 MHz) and the measured 3 dB axial ratio (AR) bandwidth is 13.9% (840–965 MHz). Both the impedance and AR bandwidth cover the worldwide UHF RFID band....

  20. A Broadband Circularly Polarized Stacked Probe-Fed Patch Antenna for UHF RFID Applications

    OpenAIRE

    Hang Leong Chung; Xianming Qing; Zhi Ning Chen

    2007-01-01

    A broadband circularly polarized stacked probe-fed antenna suitable for UHF RFID applications is presented and studied. The proposed antenna is fed by two probes which are connected to a hybrid coupler. Two parasitic patches are stacked above a primary probe-fed patch to enhance the bandwidth of the antenna. The optimized antenna prototype achieves gain of more than 6.5 dBic, axial ratio of less than 3.0 dB, and return loss of less than −15 dB over the UHF band of 820–980 MH...

  1. Orbital properties of micron-size dust determined using the Arecibo 430 MHz dual-beam radar

    Science.gov (United States)

    Janches, Diego; Meisel, David D.; Nolan, Michael C.; Bartlett, Brent D.; Mathews, John D.; Zhou, Qihou H.; Moser, Danielle E.

    Orbital results derived from radar observations of micron-size dust entering the earth's atmosphere are presented and discussed. These observations are performed using the 430 MHz Arecibo Observatory (AO) dual-beam radar system in Puerto Rico - a unique ground-base tool for the study of dust. The AO radar daily daily thousands of decelerating particles in the size range 0.5-100 microns for which precise altitude; instantaneous Doppler velocity and (linear) deceleration are obtained. These results help bridge the gap between spacecraft dust measurements and traditional meteor radar capabilities. During 2002, monthly micrometeor radar observations were performed. Each month, a minimum of one, 14 hour interval of observations (18:00-08:00 hrs LT) were carried out. During this year-long observing campaign, the antenna line feed was pointing vertically while the Gregorian feed was pointed at a zenith angle of 15 degrees. The off-vertical radar beam was initially placed pointing north and every 30 minutes was rotated 180 degrees. Preliminary results show an assymetry on the orbital properties of dust at 1 AU and indicate that the traditional idea of sporadic meteor sources may be too simplistic to describe the sporadic micrometeor complex, at least for the particle sizes detected by AO.

  2. Monitoring the yearly sporadic Micrometeor Flux into the upper Atmosphere using the Arecibo Dual-Beam 430 MHz Radar

    Science.gov (United States)

    Moser, D. E.; Janches, D.; Meisel, D. D.; Nolan, M. C.; Bartlett, B. D.; Mathews, J. D.

    2002-12-01

    A year long program of observations and study of the micrometeor flux into the upper atmosphere using the dual-beam 430 MHz Arecibo radar (AO) in Puerto Rico began in January 2002. The AO radar detects decelerating particles in the size range 0.5-100 microns for which precise altitude, instantaneous Doppler velocity, and (linear) deceleration are obtained. This provides a tool for the study of a mass-region of the interplanetary dust distribution that was previously inaccessible to ground-based instruments and helps bridge the gap between spacecraft dust measurements and traditional meteor radar capabilities. Each month, a minimum of one 14-hour interval of observations (18:00-08:00 hrs LT) is collected. The antenna line feed is pointed vertically while the Gregorian feed is pointed at a zenith angle of 15 degrees. The off-vertical radar beam is initially placed pointing north and every 30 minutes is rotated 180 degrees. Over 10000 events are observed daily inside the 300m diameter beam, within an observed altitude range of 80-140 km (150 m height resolution). With the application of a Doppler technique, instantaneous meteor velocities are obtained with errors on the order of 10-100 m/sec. Orbital results derived from the observations performed in January and June are presented and discussed.

  3. Inkjet printing of UHF antennas on corrugated cardboards for packaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Sowade, Enrico, E-mail: enrico.sowade@mb.tu-chemnitz.de [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz (Germany); Göthel, Frank [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz (Germany); Zichner, Ralf [Department Printed Functionalities, Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz (Germany); Baumann, Reinhard R. [Digital Printing and Imaging Technology, Technische Universität Chemnitz, Chemnitz (Germany); Department Printed Functionalities, Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz (Germany)

    2015-03-30

    Highlights: • Inkjet printing of UHF antennas on cardboard substrates. • Development of primer layer to compensate the absorptiveness of the cardboard and the rough surface. • Manufacturing of UHF antennas in a fully digital manner for packaging applications. - Abstract: In this study, a method based on inkjet printing has been established to develop UHF antennas on a corrugated cardboard for packaging applications. The use of such a standardized, paper-based packaging substrate as material for printing electronics is challenging in terms of its high surface roughness and high ink absorption rate, especially when depositing very thin films with inkjet printing technology. However, we could obtain well-defined silver layers on the cardboard substrates due to a primer layer approach. The primer layer is based on a UV-curable ink formulation and deposited as well as the silver ink with inkjet printing technology. Industrial relevant printheads were chosen for the deposition of the materials. The usage of inkjet printing allows highest flexibility in terms of pattern design. The primer layer was proven to optimize the surface characteristics of the substrate, mainly reducing the surface roughness and water absorptiveness. Thanks to the primer layer approach, ultra-high-frequency (UHF) radio-frequency identification (RFID) antennas were deposited by inkjet printing on the corrugated cardboards. Along with the characterization and interpretation of electrical properties of the established conductive antenna patterns, the performance of the printed antennas were analyzed in detail by measuring the scattering parameter S{sub 11} and the antenna gain.

  4. A Broadband UHF Tag Antenna For Near-Field and Far-Field RFID Communications

    Directory of Open Access Journals (Sweden)

    M. Dhaouadi

    2014-12-01

    Full Text Available The paper deals with the design of passive broadband tag antenna for Ultra-High Frequency (UHF band. The antenna is intended for both near and far fields Radio Frequency Identification (RFID applications. The meander dipole tag antenna geometry modification is designed for frequency bandwidth increasing. The measured bandwidth of the proposed broadband Tag antenna is more than 140 MHz (820–960 MHz, which can cover the entire UHF RFID band. A comparison between chip impedance of datasheet and the measured chip impedance has been used in our simulations. The proposed progressive meandered antenna structure, with an overall size of 77 mm × 14 mm × 0.787 mm, produces strong and uniform magnetic field distribution in the near-field zone. The antenna impedance is matched to common UHF chips in market simply by tuning its capacitive and inductive values since a perfect matching is required in the antenna design in order to enhance the near and the far field communications. Measurements confirm that the designed antenna exhibits good performance of Tag identification for both near-field and far-field UHF RFID applications.

  5. Improved Bagging Algorithm for Pattern Recognition in UHF Signals of Partial Discharges

    Directory of Open Access Journals (Sweden)

    Caixin Sun

    2011-07-01

    Full Text Available This paper presents an Improved Bagging Algorithm (IBA to recognize ultra-high-frequency (UHF signals of partial discharges (PDs. This approach establishes the sample information entropy for each sample and the re-sampling process of the traditional Bagging algorithm is optimized. Four typical discharge models were designed in the laboratory to simulate the internal insulation faults of power transformers. The optimized third order Peano fractal antenna was applied to capture the PD UHF signals. Multi-scale fractal dimensions as well as energy parameters extracted from the decomposed signals by wavelet packet transform were used as the characteristic parameters for pattern recognition. In order to verify the effectiveness of the proposed algorithm, the back propagation neural network (BPNN and the support vector machine (SVM based on the IBA were adopted in this paper to carry out the pattern recognition for PD UHF signals. Experimental results show that the proposed approach of IBA can effectively enhance the generalization capability and also improve the accuracy of the recognition for PD UHF signals.

  6. Inkjet printing of UHF antennas on corrugated cardboards for packaging applications

    International Nuclear Information System (INIS)

    Highlights: • Inkjet printing of UHF antennas on cardboard substrates. • Development of primer layer to compensate the absorptiveness of the cardboard and the rough surface. • Manufacturing of UHF antennas in a fully digital manner for packaging applications. - Abstract: In this study, a method based on inkjet printing has been established to develop UHF antennas on a corrugated cardboard for packaging applications. The use of such a standardized, paper-based packaging substrate as material for printing electronics is challenging in terms of its high surface roughness and high ink absorption rate, especially when depositing very thin films with inkjet printing technology. However, we could obtain well-defined silver layers on the cardboard substrates due to a primer layer approach. The primer layer is based on a UV-curable ink formulation and deposited as well as the silver ink with inkjet printing technology. Industrial relevant printheads were chosen for the deposition of the materials. The usage of inkjet printing allows highest flexibility in terms of pattern design. The primer layer was proven to optimize the surface characteristics of the substrate, mainly reducing the surface roughness and water absorptiveness. Thanks to the primer layer approach, ultra-high-frequency (UHF) radio-frequency identification (RFID) antennas were deposited by inkjet printing on the corrugated cardboards. Along with the characterization and interpretation of electrical properties of the established conductive antenna patterns, the performance of the printed antennas were analyzed in detail by measuring the scattering parameter S11 and the antenna gain

  7. Control of UHF energy absorption process by resonance method in a shielded object

    International Nuclear Information System (INIS)

    A research program has been developed to account for effect of transverse electric and magnetic fields on a biological object, reaction control of its dielectric constant change, quality factor and heat loss in UHF range in a rectangular resonator in the resonance absorption mode

  8. Comparative study of electron density from incoherent scatter measurements at Arecibo with the IRI-95 model during solar maximum

    Directory of Open Access Journals (Sweden)

    N. K. Sethi

    Full Text Available Arecibo (18.4 N, 66.7 W incoherent scatter (IS observations of electron density N(h are compared with the International Reference Ionosphere (IRI-95 during midday (10–14 h, for summer, winter and equinox, at solar maximum (1981. The N(h profiles below the F2 peak, are normalized to the peak density NmF2 of the F region and are then compared with the IRI-95 model using both the standard B0 (old option and the Gulyaeva-B0 thickness (new option. The thickness parameter B0 is obtained from the observed electron density profiles and compared with those obtained from the IRI-95 using both the options. Our studies indicate that during summer and equinox, in general, the values of electron densities at all the heights given by the IRI model (new option, are generally larger than those obtained from IS measurements. However, during winter, the agreement between the IRI and the observed values is reasonably good in the bottom part of the F2 layer but IRI underestimates electron density at F1 layer heights. The IRI profiles obtained with the old option gives much better results than those generated with the new option. Compared to the observations, the IRI profiles are found to be much thicker using Gulyaeva-B0 option than using standard B0.

    Key words: Ionosphere (modelling and forecasting

  9. The Arecibo Remote Command Center: Creating an Inspiring Environment for Astrophysics

    Science.gov (United States)

    Miller, Andy F.; Jenet, F. A.; Zermeno, A.; Stovall, K.

    2009-01-01

    At the Center for Gravitational Wave Astronomy at the University of Texas-Brownsville (UTB) we have developed the first Arecibo Remote Command Center (ARCC). The ARCC is a virtual control room where researchers and students from the high school level and higher have real time control of the world's largest single dish radio telescope at the Arecibo observatory. Here we give an overview of the project and the progress made over the past four years. Several notable accomplishments include: 1) the direct involvement of high school students in the PALFA pulsar search project at the Arecibo Observatory; 2) development of a web-based pulsar search interface which students have used to identify potential pulsar candidates; 3) completion of the ARCC room facility at the UTB campus, a state of the art room that looks like the bridge of a starship; 4) establishment of the ARCC Scholars_a program that provides undergraduate physics majors at UTB the opportunity to specialize in astrophysics and begin research early in their careers.

  10. Midnight ionosphere collapse at Arecibo and its relationship to the neutral wind, electric field, and ambipolar diffusion

    Science.gov (United States)

    Gong, Yun; Zhou, Qihou; Zhang, Shaodong; Aponte, Nestor; Sulzer, Michael; Gonzalez, Sixto

    2012-08-01

    We report the analysis of "midnight collapse," a large drop in the F-layer peak height (HmF2) around midnight, observed at Arecibo during Jan. 14-22, 2010. During the nine nights of observations, the first four nights (Jan. 14-17) exhibited modest drops in HmF2 while the last five nights (Jan. 18-22) showed more severe drops. We examine the roles played by the meridional wind, electric field, and ambipolar diffusion in driving the vertical ion motion. The collapse process can be classified into three stages: preconditioning, initial descent, and sustained descent. Severe collapses occur when HmF2 is preconditioned high prior to the collapse. Ambipolar diffusion is most important during the initial descent. Neutral wind and electric field are responsible for sustaining the collapse. During Jan. 18-22, HmF2 was pushed high by the neutral wind before the collapse started. Neutral wind and electric field were in phase during the sustained severe collapses. The diurnal tide of the meridional wind provided the general condition for the collapses. The terdiurnal tide was most important to cause the difference between the two periods in our observation. Previous studies largely emphasized meridional wind being the dominant mechanism causing midnight collapse. Our study suggests that electric field and ambipolar diffusion also play an important role and the former can be the most dominant factor in some cases.

  11. THE GALEX ARECIBO SDSS SURVEY. VII. THE BIVARIATE NEUTRAL HYDROGEN-STELLAR MASS FUNCTION FOR MASSIVE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Lemonias, Jenna J.; Schiminovich, David [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Catinella, Barbara [Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85741 Garching (Germany); Heckman, Timothy M. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Moran, Sean M., E-mail: jenna@astro.columbia.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-10-20

    We present the bivariate neutral atomic hydrogen (H I)-stellar mass function (HISMF) φ(M{sub H{sub I}}, M{sub *}) for massive (log M{sub *}/M{sub ☉} \\gt 10) galaxies derived from a sample of 480 local (0.025 < z < 0.050) galaxies observed in H I at Arecibo as part of the GALEX Arecibo SDSS Survey. We fit six different models to the HISMF and find that a Schechter function that extends down to a 1% H I gas fraction, with an additional fractional contribution below that limit, is the best parameterization of the HISMF. We calculate Ω{sub H{sub I,{sub M{sub *>10{sup 1}{sup 0}}}}} and find that massive galaxies contribute 41% of the H I density in the local universe. In addition to the binned HISMF, we derive a continuous bivariate fit, which reveals that the Schechter parameters only vary weakly with stellar mass: M{sub H{sub I}{sup *}}, the characteristic H I mass, scales as M{sub *}{sup 0.39}; α, the slope of the HISMF at moderate H I masses, scales as M{sub *}{sup 0.07}; and f, the fraction of galaxies with H I gas fraction greater than 1%, scales as M{sub *}{sup -0.24}. The variation of f with stellar mass should be a strong constraint for numerical simulations. To understand the physical mechanisms that produce the shape of the HISMF, we redefine the parameters of the Schechter function as explicit functions of stellar mass and star formation rate (SFR) to produce a trivariate fit. This analysis reveals strong trends with SFR. While M{sub H{sub I}{sup *}} varies weakly with stellar mass and SFR (M{sub H{sub I}{sup *}} ∝ M{sub *}{sup 0.22}, M{sub H{sub I}{sup *}} ∝ SFR{sup –0.03}), α is a stronger function of both stellar mass and especially SFR (α ∝ M{sub *}{sup 0.47}, α ∝ SFR{sup 0.95}). The HISMF is a crucial tool that can be used to constrain cosmological galaxy simulations, test observational predictions of the H I content of populations of galaxies, and identify galaxies whose properties deviate from average trends.

  12. Arecibo radar micrometeor studies: Interplanetary dust in the solar system and the atmospheric fate of this dust

    Science.gov (United States)

    Mathews, J.; Briczinski, S.; Meisel, D.; Zhou, Q.; Janches, D.

    Radar (head-echo) observations of micrometeors at Arecibo uniquely yield velocity, deceleration, radiant, and scattering mechanism information of large numbers of interplanetary dust particles. The resulting high accuracy meteoroid orbit determinations indicate that most of these particles are in heliocentric orbits with about 5% in hyperbolic, usually extrasolar orbits, and with a comparable fraction appearing to enter the atmosphere from highly eccentric geocentric orbits. Heliocentric orbits range from low/high inclination, prograde/retrograde, and interstellar particles are readily discerned even in the large flux of ecliptic and near-ecliptic particles. Observed particle masses range from a few micrograms to a small fraction of a nanogram, a size range that requires taking into account radiation pressure, Poynting-Robertson drag, as well as dusty plasma effects in the solar wind---particle charging and motion in the solar wind magnetic field. The atmospheric fate of these meteoroids is also of interest with 10-20% of all particles disappearing in ``terminal'' events and with perhaps 5% of the slow (15-25 km/sec) particles displaying evidence of trail-scattering with implications for the atmospheric interaction process. Terminal events are presumed to deposit the meteoroid mass as ``smoke'' particles rather than in atomic form that results from ablation. We give the micrometeoroid altitude, speed, deceleration, mass, and orbital distributions from February 2001, the first data set for which a completely automated analysis approach was employed.

  13. Miniaturized UHF, S-, and Ka-band RF MEMS Filters for Small Form Factor, High Performance EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase II of this SBIR, Harmonic Devices (HDI) proposes to develop miniaturized MEMS filters at UHF, S-band and Ka-band to address the requirements of NASA's...

  14. 一种新型宽带圆极化UHF RFID读写器天线%Novel circular polarization planar broadband antenna for UHF RFID applications

    Institute of Scientific and Technical Information of China (English)

    王斌; 何佳佳; 孔祥吉

    2015-01-01

    针对超高频射频识别(ultra high frequency radio frequency identification,UHF RFID)技术的发展需求,设计了一款覆盖UHF RFID全频段(840-960 MHz)的圆极化读写器天线.天线采用简单的平面缝隙贴片结构,利用π型线耦合馈电,获得了良好的宽带圆极化性能.重点分析了天线的宽带圆极化辐射机理和双向圆极化波的形成过程.天线的仿真和测试结果表明,S11≤-13 dB的阻抗带宽为200 MHz,3 dB轴比(axial-ratio,AR)带宽达到175MHz,频段内增益均大于3.4 dBi,且顶点的右旋圆极化(right-handed circular polarization,RHCP)电平和左旋圆极化(left-handed circular polarization,LHCP)电平差值均大于17 dB,具有较好的宽带性和抗干扰能力.仿真结果和实验测试结果的一致性良好,满足了UHF RFID读写器天线宽频带、高增益的应用要求.

  15. Comparative Method for Indirect Sensitivity Measurement of UHF RFID Reader with Respect to Interoperability and Conformance Requirements

    OpenAIRE

    Lukas Kypus; Lukas Vojtech

    2014-01-01

    There is never-ending race for the competitive advantage that forces RFID technology service integrators to focus more on used technology qualitative aspects and theirs impacts inside RFID ecosystem. This paper contributes to UHF RFID reader qualitative parameters evaluation and assessment problematic. It presents and describes in details indirect method and procedure of sensitivity measurement created for UHF RFID readers. We applied this method on RFID readers within prepared test environme...

  16. Arecibo Pulsar Survey Using ALFA. IV. Mock Spectrometer Data Analysis, Survey Sensitivity, and the Discovery of 41 Pulsars

    CERN Document Server

    Lazarus, P; Hessels, J W T; Karako-Argaman, C; Kaspi, V M; Lynch, R; Madsen, E; Patel, C; Ransom, S M; Scholz, P; Swiggum, J; Zhu, W W; Allen, B; Bogdanov, S; Camilo, F; Cardoso, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J S; Ferdman, R; Freire, P C C; Jenet, F A; Knispel, B; Lee, K J; van Leeuwen, J; Lorimer, D R; Lyne, A G; McLaughlin, M A; Siemens, X; Spitler, L G; Stairs, I H; Stovall, K; Venkataraman, A

    2015-01-01

    The on-going PALFA survey at the Arecibo Observatory began in 2004 and is searching for radio pulsars in the Galactic plane at 1.4 GHz. Observations since 2009 have been made with new wider-bandwidth spectrometers than were previously employed in this survey. A new data reduction pipeline has been in place since mid-2011 which consists of standard methods using dedispersion, searches for accelerated periodic sources, and search for single pulses, as well as new interference-excision strategies and candidate selection heuristics. This pipeline has been used to discover 41 pulsars, including 8 millisecond pulsars (MSPs; P = 100 ms that gradually becomes up to a factor of ~10 worse for P > 4 s at DM < 150 pc/cc. This degradation of sensitivity at long periods is largely due to red noise. We find that 35 +- 3% of pulsars are missed despite being bright enough to be detected in the absence of red noise. This reduced sensitivity could have implications on estimates of the number of long-period pulsars in the Gal...

  17. A High-Gain Passive UHF-RFID Tag with Increased Read Range.

    Science.gov (United States)

    Zuffanelli, Simone; Aguila, Pau; Zamora, Gerard; Paredes, Ferran; Martin, Ferran; Bonache, Jordi

    2016-01-01

    In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on a 1.25 wavelengths thin dipole antenna is presented for the first time. The length of the antenna is properly chosen in order to maximize the tag read range, while maintaining a reasonable tag size and radiation pattern. The antenna is matched to the RFID chip by means of a very simple matching network based on a shunt inductance. A tag prototype, based on the Alien Higgs-3 chip, is designed and fabricated. The overall dimensions are 400 mm × 14.6 mm, but the tag width for most of its length is delimited by the wire diameter (0.8 mm). The measured read range exhibits a maximum value of 17.5 m at the 902-928 MHz frequency band. This represents an important improvement over state-of-the-art passive UHF-RFID tags. PMID:27455274

  18. A RHCP Microstrip Antenna with Ultrawide Beamwidth for UHF Band Application

    Directory of Open Access Journals (Sweden)

    Yuan-zhu Liu

    2014-01-01

    Full Text Available A novel right-hand circularly polarized (RHCP UHF microstrip antenna with 3 dB beamwidth of more than 150° is presented in this paper. The 3 dB RHCP beamwidth can be broadened by utilizing a combined ground structure with a hollow truncated cone ground plane and a metallic rectangular plate. Optimizing the half-angle θc of cone and the cone height hcone, a 3 dB RHCP beamwidth of more than 200° can be acquired, which is about 120° greater than its corresponding regular RHCP microstrip antenna. There is a good agreement between the measured results and simulated results for the proposed antenna operating in UHF band.

  19. Arecibo and Goldstone radar evidence for boulders on near-Earth asteroids

    Science.gov (United States)

    Benner, L.; Nolan, M.; Brozovic, M.; Taylor, P.; Busch, M.; Howell, E.; Margot, J.; Giorgini, J.; Springmann, A.; Naidu, S.; Magri, C.; Shepard, M.

    2014-07-01

    Delay-Doppler radar observations of numerous near-Earth asteroids (NEAs) since 1999 have revealed many small groups of radar-bright pixels in some of the highest signal-to-noise ratio (SNR) images obtained at Arecibo and Goldstone. Many of the spots remain observable as the asteroids rotate through tens of degrees. The bright pixels are not receiver noise, self noise, or artifacts, but are real features. Clusters of bright pixels appear primarily in high-resolution radar images with resolutions of 4-19 m/pixel and usually span a few rows and columns or less, indicating that these are surface features a few tens of meters in extent or smaller. Many clusters appear near the trailing edges of the images and are adjacent to and up range from radar shadows, implying the presence of small-scale topography. To date, small groups of bright pixels have been seen on at least ten NEAs observed at high resolution, such as (in chronological order of radar detection) (101955) Bennu, (33342) 1998 WT_{24}, (100085) 1992 UY_{4}, (374851) 2006 VV_{2}, (341843) 2008 EV_{5}, (136849) 1998 CS_{1}, (308635) 2005 YU_{55}, (214869) 2007 PA_{8}, (4179) Toutatis, and 2014 BR_{57}. Of these objects, Toutatis is the largest, with a long axis of 4.6 km, and 2004 BR_{57} is the smallest, with a diameter of about 80 m. These objects also span a considerable dynamic range of shapes, spin states, and spectral classes. What causes the radar-bright pixels? Radar albedo correlates positively with increasing near-surface density, so relatively bright echoes can result from scattering off surface and near-surface features with higher densities than their surroundings. Bright echoes can also be generated by specular reflections from relatively flat surfaces oriented nearly perpendicular to the radar line-of-sight. Many of these features are located near the radar terminator where the radar line-of-sight is at grazing incidence angles, which tends to highlight small-scale topography. We suggest that a

  20. LCDM Satellites and HI Companions - The Arecibo ALFA Survey of NGC 2903

    OpenAIRE

    Irwin, J. A.; Hoffman, G.L.; Spekkens, K.; Haynes, M. P.; Giovanelli, R.; Linder, S. M.; Catinella, B.; Momjian, E.; Koribalski, B. S.; Davies, J; Brinks, E.; de Blok, W. J. G.; Putman, M. E.; Van Driel, W.

    2008-01-01

    We have conducted a deep, complete HI survey, using Arecibo/ALFA, of a field centered on the nearby, isolated galaxy, NGC 2903, which is similar to the Milky Way in its properties. The field size was 150 kpc x 260 kpc and the final velocity range spanned from 100 to 1133 km/s. The ALFA beams have been mapped as a function of azimuth and cleaned from each azimuth-specific cube prior to forming final cubes. The final HI data are sensitive down to an HI mass of 2 x 10^5 Mo and column density of ...

  1. UHF-Band Wireless Power Transfer System for Structural Health Monitoring Sensor Network

    OpenAIRE

    Tansheng Li; Kikuzo Sawada; Harutoshi Ogai; Wa Si

    2013-01-01

    For detecting and measuring health conditions of bridges, wireless sensor networks are used in these days. However, battery life is critically restricting the application and maintenance cost of sensor network systems. To extend life time, a wireless power transfer system at UHF band is introduced to supply the current wireless sensor network. This power transfer system is based on electric wave at 950 MHz. This power transfer system is redesigned for tiny power transmission, including a comb...

  2. Performance Evaluation of UHF Wireless Digital Gait Monitoring Instrumentation for Long Range Data Transmission

    OpenAIRE

    MICHAEL OLUSOPE ALADE; ADEGBERO SUNDAY AJANI

    2013-01-01

    This paper presents performance evaluation of a UHF wireless Gait monitoring instrumentation system for long distance. This improvised gait monitoring system consists of two basic units; a mobile transmitting unit sending signal at carrier frequency of 869.85 MHz and a stationary receiving unit placed at the base station. The system was implemented using flexi force sensor A201 connected with the aid of appropriate reference resistance to the operational amplifier LM324 whose outputs are fed ...

  3. Inkjet printing of UHF antennas on corrugated cardboards for packaging applications

    OpenAIRE

    Sowade, E.; Göthel, F.; Zichner, R.; R. R. Baumann

    2015-01-01

    In this study, a method based on inkjet printing has been established to develop UHF antennas on a corrugated cardboard for packaging applications. The use of such a standardized, paper-based packaging substrate as material for printing electronics is challenging in terms of its high surface roughness and high ink absorption rate, especially when depositing very thin films with inkjet printing technology. However, we could obtain well-defined silver layers on the cardboard substrates due to a...

  4. A comparison of the UHF Follow-on and MILSTAR satellite communication systems

    OpenAIRE

    Perkins, Clifton E.

    1991-01-01

    The author compares the UHF Follow-on and MILSTAR satellite communication systems. The comparison uses an analytical hierarchy process. Although the two systems have been tasked with different missions, a comparison of cost, capability, and orbit is conducted. UFO provides many of the same capabilities as MILSTAR, but on a smaller scale. Since UFO is also a new space system acquisition, it is used to compare dollars spent to field a viable communication system. A review of frequency bands, lo...

  5. A preliminary economic evaluation of Marine Corps acquisition practices: UHF satellite communication ground terminal acquisitions

    OpenAIRE

    Psillas, Christopher F.

    1989-01-01

    Economic theories and concepts are used to discuss allocating scarce fiscal resources for acquiring UHF satellite communication ground terminals. This thesis provides and overview of current acquisition practices and suggests how applied economics can explicitly aid in better decision making. Keywords: Command control and communications, Telecommunications, Demand, Supply, Acquisitions, Demand management. (KR) http://archive.org/details/preliminaryecono00psil NA NA U.S. Marine Cor...

  6. UHF RFID Antenna: Printed Dipole Antenna with a CPS Matching Circuit and Inductively Coupled Feed

    OpenAIRE

    Nenad Popović

    2011-01-01

    This paper presents simulated (WIPL‐D pro) and measured results of a UHF RFID antenna realized with a dipole matched to a CPS (Coplanar Stripline) and inductively coupled with a small rectangular loop. Such a design enables achieving and controlling high values of the inductive reactance that is necessary for obtaining good match of the antenna to an Application Specific Integrated Circuit (ASIC) chip. The antenna is characterized by a simple and robust design, which results in low‐cost re...

  7. Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment.

    Science.gov (United States)

    Liu, Jingcun; Zhang, Guogang; Dong, Jinlong; Wang, Jianhua

    2015-01-01

    Detecting partial discharge (PD) is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA) for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor's compact size makes it suitable for internal installation in high-voltage electrical equipment. PMID:26610506

  8. Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment

    Directory of Open Access Journals (Sweden)

    Jingcun Liu

    2015-11-01

    Full Text Available Detecting partial discharge (PD is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor’s compact size makes it suitable for internal installation in high-voltage electrical equipment.

  9. Understanding Electrical Treeing Phenomena in XLPE Cable Insulation Adopting UHF Technique

    Science.gov (United States)

    Sarathi, Ramanujam; Nandini, Arya; Danikas, Michael G.

    2011-03-01

    A major cause for failure of underground cables is due to formation of electrical trees in the cable insulation. A variety of tree structure can form from a defect site in cable insulation viz bush-type trees, tree-like trees, fibrillar type trees, intrinsic type, depending on the applied voltage. Weibull studies indicate that a higher applied voltage enhances the rate of tree propagation thereby reducing the life of cable insulation. Measurements of injected current during tree propagation indicates that the rise time and fall time of the signal is of few nano seconds. In the present study, an attempt has been made to identify the partial discharges caused due to inception and propagation of electrical trees adopting UHF technique. It is realized that UHF signal generated during tree growth have signal bandwidth in the range of 0.5-2.0 GHz. The formation of streamer type discharge and Townsend type discharges during tree inception and propagation alters the shape of the tree formed. The UHF signal generated due to partial discharges formed during tree growth were analyzed adopting Ternary plot, which can allow one to classify the shape of tree structure formed.

  10. The Expansion of Arecibo in Summer 2008: A Receiver at 600-1200 MHz

    Science.gov (United States)

    Jones, Kristen; Rajagopalan, G.; Whitlow, D.

    2009-01-01

    The purpose of this project is to investigate the radio frequency interference (RFI) environment seen through the Arecibo telescope and recommend necessary limits for a cooled receiver in the 600-1200 MHz regime. Preliminary discriminatory measurements were made using the Hilltop RFI Monitoring system. Strong TV and cell phone signals dominate the band from 450 to 1200 MHz. We seek to overcome this RFI for a number of reasons. It is feasible that the dish will see less troublesome RFI than the Hilltop Monitoring sees. Additionally, this region is astronomically essential, as it is ideal for both pulsar research and high z HI studies. We have constructed an antenna and receiver optimized in the 600-1200 MHz band and have installed them in the Gregorian Dome. We are currently working to focus and calibrate the receiver and to produce spectra across the band from sample regions of the entire Arecibo beam. This information will guide the limits and filters necessary to make a cooled receiver functional in this useful region. We graciously thank the National Science Foundation's Research Experience for Undergraduates program for funding this research.

  11. Target Selection for the Arecibo Pisces-Perseus Supercluster Survey (APPSS)

    Science.gov (United States)

    Craig, David W.; O'Donoghue, Aileen A.; Haynes, Martha P.; Rosenberg, Jessica L.; Venkatesan, Aparna; Hallenbeck, Gregory L.; Jones, Michael; Koopmann, Rebecca A.; Undergraduate ALFALFA Team

    2016-01-01

    The Arecibo Pisces-Perseus Supercluster Survey (APPSS) is a new large targeted HI survey now underway using Arecibo's L-band Wide receiver system. A major goal is to constrain models of the Pisces Perseus infall, producing 5-σ detections of infall motions ˜500 km s-1. We are targeting sources that are likely to be at the PPS distance, but that are just below the the HI mass detection threshold of the ALFALFA survey. We expect to identify ˜800 objects of mass ˜108—9 M⊙ which will alllow us to constrain the lower mass end of the HI mass function in this infall environment.We have pursued a multi-pronged approach to target selection for this survey. Sources from ALFALFA, SDSS, and the GALEX GCAT single source catalogs were matched and intercompared via multi-band color photometry, surface brightnesses, and appearance in SDSS images. Final target selection based on visual inspection of SDSS images was found to correlate well with a color-selection technique based on GALEX/NUV - SDSS/r. Along with the details of the source selection we will discuss the facilitation and implementation of this process via a multi-institution collaborative website, and early results from the APSS survey.This work has been supported by NSF grant AST-1211005.

  12. The GALEX Arecibo SDSS survey: III. Evidence for the Inside-Out Formation of Galactic Disks

    CERN Document Server

    Wang, Jing; Overzier, Roderik; Catinella, Barbara; Schminovich, David; Heckman, Timothy M; Moran, Sean M; Haynes, Martha P; Giovanelli, Riccardo; Kong, Xu

    2010-01-01

    We analyze a sample of galaxies with stellar masses greater than $10^{10} M_{\\odot}$ and with redshifts in the range $0.025Arecibo SDSS Survey (GASS) or from the Arecibo Legacy Fast ALFA survey (ALFALFA). At a given value of $M_*$, our sample consists primarily of galaxies that are more HI-rich than average. We constructed a series of three control samples for comparison with these HI-rich galaxies. As expected, HI-rich galaxies differ strongly from galaxies of same stellar mass that are selected without regard to HI content. The majority of these differences are attributable to the fact that galaxies with more gas are bluer and more actively star-forming. In order to identify those galaxy properties that are causally connected with HI content, we compare results derived for the HI sample with those derived for galaxies matched in stellar mass, size and NUV-$r$ colour. The only photometric property that is clearly attributable to incre...

  13. A blind HI Mass Function from the Arecibo Ultra-Deep Survey (AUDS)

    CERN Document Server

    Hoppmann, L; Freudling, W; Zwaan, M A; Minchin, R F; Calabretta, M R

    2015-01-01

    The Arecibo Ultra Deep Survey (AUDS) combines the unique sensitivity of the telescope with the wide field of the Arecibo L-band Feed Array (ALFA) to directly detect 21cm HI emission from galaxies at distances beyond the local Universe bounded by the lower frequency limit of ALFA (z=0.16). AUDS has collected 1110 hours of integration time in two fields with a combined area of 1.35 square degrees. In this paper we present data from 50% of the total survey, corresponding to a sensitivity level of 80 micro-Jy. We discuss the data reduction, the search for galaxies, parametrisation, optical identification and completeness. We detect 102 galaxies in the mass range of log M_HI/M_sun-2log h=5.6-10.3. We compute the HI mass function (HIMF) at the highest redshifts so far measured. A fit of a Schechter function results in alpha=-1.37+-0.03, Phi=(7.72+-1.4)*10^3 h^3/Mpc^3 and log M_HI/M_sun=9.75+-0.041+2log h. Using the measured HIMF, we find a cosmic HI density of Omega_HI=(2.33+-0.07)*10^-4/h for the sample z=0.065. W...

  14. The Arecibo Legacy Fast ALFA Survey : X. The HI Mass Function and Omega_HI From the 40% ALFALFA Survey

    NARCIS (Netherlands)

    Martin, Ann M.; Papastergis, Emmanouil; Giovanelli, Riccardo; Haynes, Martha P.; Springob, Christopher M.; Stierwalt, Sabrina

    2010-01-01

    The Arecibo Legacy Fast ALFA (ALFALFA) survey has completed source extraction for 40% of its total sky area, resulting in the largest sample of HI-selected galaxies to date. We measure the HI mass function from a sample of 10,119 galaxies with 6.2

  15. A Novel Technology for Motion Capture Using Passive UHF RFID Tags

    DEFF Research Database (Denmark)

    Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund;

    2013-01-01

    Although there are several existing methods for human motion capture, they all have important limitations and hence there is the need to explore fundamentally new approaches. Here we present a method based on a Radio Frequency IDentification (RFID) system with passive Ultra High Frequency (UHF...... walking. The reference joint angles for the validation were obtained by an optoelectronic system. Although the method is in its initial phase of development, the results of the validation are promising and show that the movement information can be extracted from the RFID response signals....

  16. Effects of wind turbines on UHF television reception: field tests in Denmark, November 1991

    International Nuclear Information System (INIS)

    As a result of a planning application for a wind farm comprising 20 wind turbines at Tynewydd Farm, Gilfach Goch in Mid Glamorgan, it became necessary to produce a Report discussing any detrimental effects the proposal might have on UHF television reception. In order to make that Report as definitive as possible, it was decided to carry out field tests on the exact model of wind turbine to be used to Tynewydd. This required a field trip to Denmark, and the opportunity was taken to make measurements on two other models of turbine at the same time. This Report presents the analysis of the results for all three turbines. (Author)

  17. NASA Standard Initiator Susceptibility to UHF and S-Band Radio Frequency Power and Lightning Strikes

    Science.gov (United States)

    Burnham, Karen; Scully, Robert; Norgard, John

    2013-01-01

    The NASA Standard Initiator (NSI) is an important piece of pyrotechnic equipment used in many space applications. This presentation will outline the results of a series of tests done at UHF and S-Band frequencies to determine NSI susceptibility to Radio Frequency (RF) power. The results show significant susceptibility to pulsed RF power in the S-Band region. Additional testing with lightning pulses injected into the firing line harness, modelling the indirect effects of a lightning strike to a spacecraft, showed no vulnerability

  18. Towards Washable Electrotextile UHF RFID Tags: Reliability Study of Epoxy-Coated Copper Fabric Antennas

    Directory of Open Access Journals (Sweden)

    Shiqi Wang

    2015-01-01

    Full Text Available We investigate the impact of washing on the performance of passive UHF RFID tags based on dipole antennas fabricated from copper fabric and coated with protective epoxy coating. Initially, the tags achieved read ranges of about 8 meters, under the European RFID emission regulation. To assess the impact of washing on the performance of the tags, they were washed repeatedly in a washing machine and measured after every washing cycle. Despite the reliability challenges related to mechanical stress, the used epoxy coating was found to be a promising coating for electrotextile tags in moist conditions.

  19. Effects of wind turbines on UHF television reception: field tests in Denmark

    International Nuclear Information System (INIS)

    As a result of a planning application for a windfarm comprising 20 wind turbines at Tynewydd Farm, Gilfach Goch in Mid Glamorgan, a report discussing any detrimental effects the proposal might have on u.h.f. television reception was produced. In order to make the report as definitive as possible, it was decided to carry out field tests on the exact model of wind turbine to be used at Tynewydd. This required a field trip to Denmark, and the opportunity was taken to make measurements on two other models of turbine at the same time. This report presents the analysis of the results for all three turbines. (author)

  20. Propagation effects by roadside trees measured at UHF and L-band for mobile satellite systems

    Science.gov (United States)

    Goldhirsh, Julius; Vogel, Wolfhard J.

    1988-01-01

    Propagation field tests were performed in Central Maryland and involved a helicopter and mobile van as the source and receiving platforms, respectively. Tests were implemented at both UHF (870 MHz) and L-band (1.5 GHz) during a period in which the trees were in full blossom and contained maximum moisture. Cumulative fade distributions were determined from the data for various fixed elevation angles, side of the road driving, and road types for both worst and best case path geometries and for overall average road conditions.

  1. Measurements of the propagation of UHF radio waves on an underground railway train

    OpenAIRE

    Zhang, YP; Jiang, ZR; Ng, TS; Sheng, JH

    2000-01-01

    Measurements of the natural propagation of UHF radio waves on an underground train are reported. Of prime interest are the natural propagation attenuation and the median signal level behavior. The propagation attenuation rates or the median signal level behaviors are found to correlate with the train carriages and frequency. On the front carriage, the propagation attenuation rate is 54 dB/100 m at 465 MHz and reduced to 21 dB/100 m at 820 MHz. However, on the rear carriage, it becomes 14.8 dB...

  2. Seasonal variability and descent of mid-latitude sporadic E layers at Arecibo

    Directory of Open Access Journals (Sweden)

    N. Christakis

    2009-03-01

    Full Text Available Sporadic E layers (Es follow regular daily patterns in variability and altitude descent, which are determined primarily by the vertical tidal wind shears in the lower thermosphere. In the present study a large set of sporadic E layer incoherent scatter radar (ISR measurements are analyzed. These were made at Arecibo (Geog. Lat. ~18° N; Magnetic Dip ~50° over many years with ISR runs lasting from several hours to several days, covering evenly all seasons. A new methodology is applied, in which both weak and strong layers are clearly traced by using the vertical electron density gradient as a function of altitude and time. Taking a time base equal to the 24-h local day, statistics were obtained on the seasonal behavior of the diurnal and semidiurnal tidal variability and altitude descent patterns of sporadic E at Arecibo. The diurnal tide, most likely the S(1,1 tide with a vertical wavelength around 25 km, controls fully the formation and descent of the metallic Es layers at low altitudes below 110 km. At higher altitudes, there are two prevailing layers formed presumably by vertical wind shears associated mainly with semidiurnal tides. These include: 1 a daytime layer starting at ~130 km around midday and descending down to 105 km by local midnight, and 2 a less frequent and weaker nighttime layer which starts prior to midnight at ~130 km, descending downwards at somewhat faster rate to reach 110 km by sunrise. The diurnal and semidiurnal-like pattern prevails, with some differences, in all seasons. The differences in occurrence, strength and descending speeds between the daytime and nighttime upper layers are not well understood from the present data alone and require further study.

  3. Illustration of the Impedance Behaviour of Extremely Low-Profile Coupled Shorted-Patches Antennas for UHF RFID of People

    Directory of Open Access Journals (Sweden)

    Milan Svanda

    2014-01-01

    Full Text Available The recently introduced coupled shorted-patches technique for the design of extremely low-profile UHF RFID tag antennas is used to illustrate the flexibility of selected feeding methods for tuning the antenna input impedance for the complex values required for matching with typical RFID chips. We present parametric studies of the impedance behaviour of dipole-excited and directly excited antennas designed for radiofrequency identification of people in the European UHF frequency band. Our study can significantly facilitate the design of this class of on-body tag antennas.

  4. Design of a Circularly Polarized Z-Slot Antenna with Isotropic Pattern for the UHF RFID Reader of WSN

    OpenAIRE

    Jongan Park; Jonghun Chun; Gwangwon Kang; Sungkwan Kang; Youngeun An

    2014-01-01

    In an antenna for a UHF RFID reader of wireless sensor networks (WSN), receiver sensitivity in sensing multitags from remote distances is an important performance index. This study designed a dual structured Z-slot antenna with optimized receiver sensitivity to enhance the sensitivity to a circularly polarized antenna with an isotropic pattern for a UHF RFID. Through analysis of performance in the designed antenna, the following was verified: return loss (S11) was about −62.21 dB at 925.25 MH...

  5. Improving the range of UHF RFID transponders using solar energy harvesting under low light conditions

    Science.gov (United States)

    Ascher, A.; Lehner, M.; Eberhardt, M.; Biebl, E.

    2015-11-01

    The sensitivity of passive UHF RFID transponders (Radio Frequency Identification) is the key issue, which determines the maximum read range of an UHF RFID system. During this work the ability of improving the sensitivity using solar energy harvesting, especially for low light conditions, is shown. To use the additional energy harvested from the examined silicon and organic solar cells, the passive RFID system is changed into a semi-active one. This needs no changes on the reader hardware itself, only the used RFIC (Radio Frequency Integrated Circuit) of the transponder has to possess an additional input pin for an external supply voltage. The silicon and organic cells are evaluated and compared to each other regarding their low light performance. The different cells are examined in a shielded box, which is protected from the environmental lighting. Additionally, a demonstrator is shown, which makes the measurement of the extended read range with respect to the lighting conditions possible. If the cells are completely darkened, the sensitivity gain is ascertained using high capacity super caps. Due to the measurements an enhancement in range up to 70 % could be guaranteed even under low light conditions.

  6. LS Channel Estimation and Signal Separation for UHF RFID Tag Collision Recovery on the Physical Layer.

    Science.gov (United States)

    Duan, Hanjun; Wu, Haifeng; Zeng, Yu; Chen, Yuebin

    2016-01-01

    In a passive ultra-high frequency (UHF) radio-frequency identification (RFID) system, tag collision is generally resolved on a medium access control (MAC) layer. However, some of collided tag signals could be recovered on a physical (PHY) layer and, thus, enhance the identification efficiency of the RFID system. For the recovery on the PHY layer, channel estimation is a critical issue. Good channel estimation will help to recover the collided signals. Existing channel estimates work well for two collided tags. When the number of collided tags is beyond two, however, the existing estimates have more estimation errors. In this paper, we propose a novel channel estimate for the UHF RFID system. It adopts an orthogonal matrix based on the information of preambles which is known for a reader and applies a minimum-mean-square-error (MMSE) criterion to estimate channels. From the estimated channel, we could accurately separate the collided signals and recover them. By means of numerical results, we show that the proposed estimate has lower estimation errors and higher separation efficiency than the existing estimates. PMID:27023560

  7. LS Channel Estimation and Signal Separation for UHF RFID Tag Collision Recovery on the Physical Layer

    Directory of Open Access Journals (Sweden)

    Hanjun Duan

    2016-03-01

    Full Text Available In a passive ultra-high frequency (UHF radio-frequency identification (RFID system, tag collision is generally resolved on a medium access control (MAC layer. However, some of collided tag signals could be recovered on a physical (PHY layer and, thus, enhance the identification efficiency of the RFID system. For the recovery on the PHY layer, channel estimation is a critical issue. Good channel estimation will help to recover the collided signals. Existing channel estimates work well for two collided tags. When the number of collided tags is beyond two, however, the existing estimates have more estimation errors. In this paper, we propose a novel channel estimate for the UHF RFID system. It adopts an orthogonal matrix based on the information of preambles which is known for a reader and applies a minimum-mean-square-error (MMSE criterion to estimate channels. From the estimated channel, we could accurately separate the collided signals and recover them. By means of numerical results, we show that the proposed estimate has lower estimation errors and higher separation efficiency than the existing estimates.

  8. The Design and Implementation of Black Tea Traceability System Based on UHF RFID

    Institute of Scientific and Technical Information of China (English)

    Caijin; LING; Jinxin; LIU; Jiayao; WU; Qiushuang; WANG; Shumei; LIU; Haiqiang; CHEN; Chaoyi; ZHAO

    2014-01-01

    In order to realize the whole process of consumer- producer bidirectional traceability and distinguish the true from the false,according to Yinghong 9,planting,processing and circulation situation,we introduce UHF RFID and Network information technology,to design and develop the UHF RFID black tea traceability system.The system adopts.NET technology,uses Microsoft Visual Studio 2010 + VB.NET,Microsoft SQL SERVER 2005,T-SQL language for development and design,and uses the network architecture of C /S combined with B /S,to randomly generate ID with 20 bit code and label,thereby forming the only corresponding relation and pointing to the corresponding batch and product types.The technology mode using three-layer structure for development realizes the functions of data collection,tracing,sharing and query.The data and business processing are concentrated on the server,simplifying the development,use and maintenance of system.We build and implement Yinghong 9 black tea traceability system,to the needs of government,the public and the producers for Yinghong 9 brand protection,product quality tracking and market regulation.

  9. An ultra low-voltage, low-power baseband-processor for UHF RFID tag

    Institute of Scientific and Technical Information of China (English)

    Yan HE; Jianyun HU; Hao MIN

    2008-01-01

    A novel ultra low-voltage, low-power baseband-processor for UHF radio frequency identification (RFID) tag is presented here. The baseband-processor is compa-tible with the EPCTM class-1 generation-2 (C1G2) UHF RFID protocol, and fits the requirements of ultra low-power of passive tags. Based on the analysis of the special power consumption of the tag, a new architecture is proposed. A novel scheme for generating pseudo-random numbers as well as a new method of partial-decoding is developed. Besides, other low-power techniques are also adopted for the special baseband-processor which imple-ments complex functions, such as encoding/coding, anti-collision and authorization scheme, and reading/writing operation to EEPROM. The chip was fabricated in 0.35 μm 1P3M standard CMOS process. Experimental results show that it achieves low power operation of 3.15 μW @ 1.5 V with the core area of 1.1 mm× 0.8 mm.

  10. Study of the frequency modulation of various U.H.F. signals occurring in a linear electron accelerator; Etude de la modulation de frequence de divers signaux U.H.F. existant dans un accelerateur lineaire d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bergere, R.; Veyssiere, A.; Daujat, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    This paper contains a digest of a series of studies on the frequency modulation of U.H.F. fields and signals associated with the linear electron accelerator at Saclay. We first consider the frequency modulation of a U. H. F. pulse before its injection into an accelerating structure and after its subsequent propagation when no accelerated electrons are present. We then apply a similar analysis to the frequency modulation due to the direct interaction of the electron beam itself, and the accelerating U.H.F. fields. Finally we consider the phase modulation of the elementary electron packet itself. This phase modulation can be correctly interpreted by considering the dynamics of the electron beam as such. This analysis moreover, gives a correct interpretation of the evolution of the phase modulation with time, as the elementary electron packets move along with the sinusoidal U.H.F. accelerating fields. (authors) [French] Cet article resume les etudes faites sur l'accelerateur lineaire d'electrons de Saclay a propos de la modulation de frequence des divers signaux U.H.F. presents autour de l'accelerateur. On etudie d'abord la modulation de frequence des impulsions U.H.F. entrant sur la structure acceleratrice ou transmises par cette structure en l'absence de faisceau d'electrons acceleres. On analyse ensuite la modulation de frequence resultant de l'interaction d'une de ces ondes avec le faisceau d'electrons acceleres. On etudie enfin, la modulation de phase des divers paquets elementaires constituant une impulsion d'electrons acceleres. On montre comment cette modulation de phase peut s'expliquer par des considerations sur la dynamique du faisceau et conduire a une representation dans les divers cas possibles de l'evolution de la phase d'accrochage des electrons sur l'onde sinusoidale progressive de champ accelerateur. (auteurs)

  11. Analysis and Design of a Long Range PTFE Substrate UHF RFID Tag for Cargo Container Identification

    Science.gov (United States)

    Petrariu, Adrian-Ioan; Popa, Valentin

    2016-01-01

    In this paper, a high-performances microstrip antenna for UHF (ultra high frequency) RFID (radio frequency identification) tag is designed, prototyped and tested. The antenna consists of two main components: a 1.52 mm RT/duroid 5880 laminate substrate on which the antenna is designed and a 10 mm polytetrafluoroethylene (PTFE) dielectric material placed as a separator between the antenna and the reference ground plane for the microstrip antenna. With this structure, the RFID tag can reach a maximum reading distance of 19 m, although the antenna has a compact size of 80 mm × 50 mm. The long reading distance is obtained by attaching to the antenna an RFID chip that can provide a reading sensitivity of -20.5 dBm. The high bandwidth from 677 MHz to 947 MHz measured at -10 dB, makes the tag being usable worldwide especially for cargo container identification, the main purpose of this research.

  12. The Ionospheric Model Adaptation to the Auroral Latitudes With UHF EISCAT Radar and Tromso Magnetometer Data

    Science.gov (United States)

    Nikolaeva, Vera; Gordeev, Evgeny; Kotikov, Andrey

    E-layer Auroral Ionosphere Model (E-AIM) developed in Arctic and Antarctic Research Institute can provide temporal and spatial distribution of the main ionosphere parameters: ion and electron density distribution in the altitude range from 90 to 150 km. The statistical study of E-layer electron density dependence on substorm activity was made to improve model results in high latitudes. About fifty substorms were included to the data analysis. Particular attention was paid to the dynamics of magnetic disturbances and ionospheric parameters measured by the radar. Correlation of electron density values measured by the UHF EISCAT incoherent scattering radar with geomagnetic indices was determined. Applicability of geomagnetic indices as input parameters of the local E-AIM model was estimated.

  13. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags.

    Science.gov (United States)

    Rokunuzzaman, Md; Islam, Mohammad Tariqul; Rowe, Wayne S T; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919-923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for 'place and tag' application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP). PMID:27533470

  14. Design of an ultra-low-power digital processor for passive UHF RFID tags

    International Nuclear Information System (INIS)

    A new architecture of digital processors for passive UHF radio-frequency identification tags is proposed. This architecture is based on ISO/IEC 18000-6C and targeted at ultra-low power consumption. By applying methods like system-level power management, global clock gating and low voltage implementation, the total power of the design is reduced to a few microwatts. In addition, an innovative way for the design of a true RNG is presented, which contributes to both low power and secure data transaction. The digital processor is verified by an integrated FPGA platform and implemented by the Synopsys design kit for ASIC flows. The design fits different CMOS technologies and has been taped out using the 2P4M 0.35 μm process of Chartered Semiconductor.

  15. Wide-Range Adaptive RF-to-DC Power Converter for UHF RFIDs

    KAUST Repository

    Ouda, Mahmoud H.

    2016-07-27

    A wide-range, differential, cross-coupled rectifier is proposed with an extended dynamic range of input RF power that enables wireless powering from varying distances. The proposed architecture mitigates the reverse-leakage problem in conven- tional, cross-coupled rectifiers without degrading sensitivity. A prototype is designed for UHF RFID applications, and is imple- mented using 0.18 μ m CMOS technology. On-chip measurements demonstrate a sensitivity of − 18 dBm for 1 V output over a 100 k Ω load and a peak RF-to-DC power conversion efficiency of 65%. A conventional, fully cross-coupled rectifier is fabricated along- side for comparison and the proposed rectifier shows more than 2 × increase in dynamic range and a 25% boosting in output voltage than the conventional rectifier

  16. Low-cost low-power UHF RFID tag with on-chip antenna

    International Nuclear Information System (INIS)

    This paper presents an EPC Class 1 Generation 2 compatible tag with on-chip antenna implemented in the SMIC 0.18 μm standard CMOS process. The UHF tag chip includes an RF/analog front-end, a digital baseband, and a 640-bit EEPROM memory. The on-chip antenna is optimized based on a novel parasitic-aware model. The rectifier is optimized to achieve a power conversion efficiency up to 40% by applying a self-bias feedback and threshold compensation techniques. A good match between the tag circuits and the on-chip antenna is realized by adjusting the rectifier input impedance. Measurements show that the presented tag can achieve a communication range of 1 cm with 1 W reader output power using a 1 x 1 cm2 single-turn loop reader antenna.

  17. A passive UHF RFID tag with a dynamic-Vth-cancellation rectifier

    International Nuclear Information System (INIS)

    This paper presents a passive UHF RFID tag with a dynamic-Vth-cancellation (DVC) rectifier. In the rectifier, the threshold voltages of MOSFETs are cancelled by applying gate bias voltages, which are dynamically changed according to the states of the MOSFETs. The DVC rectifier enables both low ON-resistance and small reverse leakage of the MOSFETs, resulting in high power conversion efficiency (PCE). An area-efficient demodulator with a novel average detector is also designed, which takes advantage of the rectifier's first stage as the envelope detector. The whole tag chip is implemented in a 0.18 μm CMOS process with a die size of 880 × 950 μm2. Measurement results show that the rectifier achieves a maximum PCE of 53.7% with 80 kΩ resistor load. (semiconductor integrated circuits)

  18. Design of a passive UHF RFID tag for the ISO18000-6C protocol

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yao; Wen Guangjun; Mao Wei; He Yanli; Zhu Xueyong, E-mail: wangyao220597@yahoo.com.cn [RFIC Laboratory CICS, School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu 611731 (China)

    2011-05-15

    This paper presents a new fully integrated wide-range UHF passive RFID tag chip design that is compatible with the ISO18000-6C protocol. In order to reduce the die area, an ultra-low power CMOS voltage regulator without resistors and an area-efficient amplitude shift keying demodulator with a novel adaptive average generator are both adopted. A low power clock generator is designed to guarantee the accuracy of the clock under {+-}4%. As the clock gating technology is employed to reduce the power consumption of the baseband processor, the total power consumption of the tag is about 14 {mu}W with a sensitivity of -9.5 dBm. The detection distance can reach about 5 m under 4 W effective isotropic radiated power. The whole tag is fabricated in TSMC 0.18 {mu}m CMOS technology and the chip size is 880 x 880 {mu}m{sup 2}. (semiconductor integrated circuits)

  19. Design of an ultra-low-power digital processor for passive UHF RFID tags

    Energy Technology Data Exchange (ETDEWEB)

    Shi Wanggen; Zhuang Yiqi; Li Xiaoming; Wang Xianghua; Jin Zhao; Wang Dan, E-mail: wanggen_shi@163.co [Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Institute of Microelectronics, Xidian University, Xi' an 710071 (China)

    2009-04-15

    A new architecture of digital processors for passive UHF radio-frequency identification tags is proposed. This architecture is based on ISO/IEC 18000-6C and targeted at ultra-low power consumption. By applying methods like system-level power management, global clock gating and low voltage implementation, the total power of the design is reduced to a few microwatts. In addition, an innovative way for the design of a true RNG is presented, which contributes to both low power and secure data transaction. The digital processor is verified by an integrated FPGA platform and implemented by the Synopsys design kit for ASIC flows. The design fits different CMOS technologies and has been taped out using the 2P4M 0.35 mum process of Chartered Semiconductor.

  20. Design of a passive UHF RFID tag for the ISO18000-6C protocol

    International Nuclear Information System (INIS)

    This paper presents a new fully integrated wide-range UHF passive RFID tag chip design that is compatible with the ISO18000-6C protocol. In order to reduce the die area, an ultra-low power CMOS voltage regulator without resistors and an area-efficient amplitude shift keying demodulator with a novel adaptive average generator are both adopted. A low power clock generator is designed to guarantee the accuracy of the clock under ±4%. As the clock gating technology is employed to reduce the power consumption of the baseband processor, the total power consumption of the tag is about 14 μW with a sensitivity of -9.5 dBm. The detection distance can reach about 5 m under 4 W effective isotropic radiated power. The whole tag is fabricated in TSMC 0.18 μm CMOS technology and the chip size is 880 x 880 μm2. (semiconductor integrated circuits)

  1. Low-cost low-power UHF RFID tag with on-chip antenna

    Energy Technology Data Exchange (ETDEWEB)

    Xi Jingtian; Yan Na; Che Wenyi; Xu Conghui; Wang Xiao; Yang Yuqing; Jian Hongyan; Min Hao, E-mail: jtxi@fudan.edu.c [State Key Laboratory of ASIC and System, Auto-ID Laboratory, Fudan University, Shanghai 201203 (China)

    2009-07-15

    This paper presents an EPC Class 1 Generation 2 compatible tag with on-chip antenna implemented in the SMIC 0.18 {mu}m standard CMOS process. The UHF tag chip includes an RF/analog front-end, a digital baseband, and a 640-bit EEPROM memory. The on-chip antenna is optimized based on a novel parasitic-aware model. The rectifier is optimized to achieve a power conversion efficiency up to 40% by applying a self-bias feedback and threshold compensation techniques. A good match between the tag circuits and the on-chip antenna is realized by adjusting the rectifier input impedance. Measurements show that the presented tag can achieve a communication range of 1 cm with 1 W reader output power using a 1 x 1 cm{sup 2} single-turn loop reader antenna.

  2. Path Loss Prediction Model For UHF Radiowaves Propagation In Akure Metropolis

    Directory of Open Access Journals (Sweden)

    Akingbade Kayode Francis

    2014-06-01

    Full Text Available Propagation path loss models play an important role in the design of cellular systems to specify key system parameters such as transmission power, frequency, antenna heights, and so on. Several models have been proposed for cellular systems operating in different environments (indoor, outdoor, urban, suburban, and rural. This work sets out to predict the path loss of a UHF channel along three routes in Akure metropolis using existing models (Friis, Okumura-Hata. Broadcast signal field strength measurements were taken across the three routes. Measured values were compared with the different models prediction to determine model suitable for the city. Consequently, a modified Hata’ model was developed which can be deployed by engineers in radio communications system planning and design.

  3. OKUMURA-HATA: A PERFECT MODEL FOR DRIVING ROUTE UHF INVESTIGATION

    Directory of Open Access Journals (Sweden)

    Omohimire P. Omolaye

    2015-09-01

    Full Text Available In today’s competitive world, a successful utility must take maximum advantage of its resources, from people to equipment to information. Using GIS on RF to integrate geographic with other corporate data has become absolutely vital to this task. The truthfulness and understandability of information is dependent upon the way it is presented. Urban planner, biologist, geologist, hydrological engineer and RF engineer tend to discuss some common factor of interest by having a better understanding of their environment (the geographic space of their study area. All these professionals work with data that relates to space. Most precisely, they deal with questions related to geographic space, which might informally be characterized as having positioned data to the earth’s surface. In this paper, we investigate and predict best model suitable for driving route of UHF wave propagation in Ondo state, Nigeria by comparing measured values using GIS equipment with the empirical results.

  4. Antenna Design for Semi-Passive UHF RFID Transponder with Energy Harvester

    Directory of Open Access Journals (Sweden)

    P. Jankowski-Mihulowicz

    2015-09-01

    Full Text Available A novel microstrip antenna which is dedicated to UHF semi-passive RFID transponders with an energy harvester is presented in this paper. The antenna structure designed and simulated by using Mentor Graphics HyperLynx 3D EM software is described in details. The modeling and simulation results along with comparison with experimental data are analyzed and concluded. The main goal of the project is the need to eliminate a traditional battery form the transponder structure. The energy harvesting block, which is used instead, converts ambient energy (electromagnetic energy of typical radio communication system into electrical power for internal circuitry. The additional function (gathering extra energy of the transponder antenna causes the necessity to create new designs in this scope.

  5. A Method for Measuring the Radiation Pattern of UHF RFID Transponders

    Directory of Open Access Journals (Sweden)

    Jankowski-Mihułowicz Piotr

    2016-06-01

    Full Text Available The operating principles of RFID antennas should be considered differently than it is applied in the classical theory of radio communication systems. The procedure of measuring the radiation pattern of antennas that could be applied to RFID transponders operating in the UHF band is seldom discussed correctly in the scientific literature. The problem consists in the variability of the RFID chip impedance that strongly influences measurement results. The authors propose the proper methodology for determining the radiation pattern with respect to an individual transponder as well as an electronically tagged object. The advantage of the solution consists in the possibility of using components of different measuring systems that are available in typical antenna laboratories. The proposed procedure is particularly important in terms of parameter validation - the identification efficiency and costs of an RFID system implementation can be evaluated properly only on the basis of real values of considered parameters.

  6. Design of an ultra-low-power digital processor for passive UHF RFID tags

    Institute of Scientific and Technical Information of China (English)

    Shi Wanggen; Zhuang Yiqi; Li Xiaoming; Wang Xianghua; Jin Zhao; Wang Dan

    2009-01-01

    A new architecture of digital processors for passive UHF radio-frequency identification tags is proposed.This architecture is based on ISO/IEC 18000-6C and targeted at ultra-low power consumption.By applying methods like system-level power management,global clock gating and low voltage implementation,the total power of the design is reduced to a few microwatts.In addition,an innovative way for the design of a true RNG is presented,which contributes to both low power and secure data transaction.The digital processor is verified by an integrated FPGA platform and implemented by the Synopsys design kit for ASIC flows.The design fits different CMOS technologies and has been taped out using the 2P4M 0.35μm process of Chartered Semiconductor.

  7. Design of an ultra-low-power digital processor for passive UHF RFID tags

    Science.gov (United States)

    Wanggen, Shi; Yiqi, Zhuang; Xiaoming, Li; Xianghua, Wang; Zhao, Jin; Dan, Wang

    2009-04-01

    A new architecture of digital processors for passive UHF radio-frequency identification tags is proposed. This architecture is based on ISO/IEC 18000-6C and targeted at ultra-low power consumption. By applying methods like system-level power management, global clock gating and low voltage implementation, the total power of the design is reduced to a few microwatts. In addition, an innovative way for the design of a true RNG is presented, which contributes to both low power and secure data transaction. The digital processor is verified by an integrated FPGA platform and implemented by the Synopsys design kit for ASIC flows. The design fits different CMOS technologies and has been taped out using the 2P4M 0.35 μm process of Chartered Semiconductor.

  8. LCDM Satellites and HI Companions - The Arecibo ALFA Survey of NGC 2903

    CERN Document Server

    Irwin, J A; Spekkens, K; Haynes, M P; Giovanelli, R; Linder, S M; Catinella, B; Momjian, E; Koribalski, B S; Davies, J; Brinks, E; De Blok, W J G; Putman, M E; Van Driel, W

    2008-01-01

    We have conducted a deep, complete HI survey, using Arecibo/ALFA, of a field centered on the nearby, isolated galaxy, NGC 2903, which is similar to the Milky Way in its properties. The field size was 150 kpc x 260 kpc and the final velocity range spanned from 100 to 1133 km/s. The ALFA beams have been mapped as a function of azimuth and cleaned from each azimuth-specific cube prior to forming final cubes. The final HI data are sensitive down to an HI mass of 2 x 10^5 Mo and column density of 2 x 10^{17} cm^{-2} at the 3sigma x 2deltaV level, where sigma is the rms noise level and deltaV is the velocity resolution. NGC 2903 is found to have an HI envelope that is larger than previously known, extending to at least 3 times the optical diameter of the galaxy. Our search for companions yields one new discovery with an HI mass of 2.6 x 10^6 Mo. The companion is 64 kpc from NGC 2903 in projection, is likely associated with a small optical galaxy of similar total stellar mass, and is dark matter dominated, with a to...

  9. New Discoveries from the Arecibo 327 MHz Drift Pulsar Survey Radio Transient Search

    CERN Document Server

    Deneva, J S; McLaughlin, M A; Bagchi, M; Bates, S D; Freire, P C C; Martinez, J G; Jenet, F; Garver-Daniels, N

    2016-01-01

    We present Clusterrank, a new algorithm for identifying dispersed astrophysical pulses. Such pulses are commonly detected from Galactic pulsars and rotating radio transients (RRATs), which are neutron stars with sporadic radio emission. More recently, isolated, highly dispersed pulses dubbed fast radio bursts (FRBs) have been identified as the potential signature of an extragalactic cataclysmic radio source distinct from pulsars and RRATs. Clusterrank helped us discover 14 pulsars and 8 RRATs in data from the Arecibo 327 MHz Drift Pulsar Survey (AO327). The new RRATs have DMs in the range $23.5 - 86.6$ pc cm$^{-3}$ and periods in the range $0.172 - 3.901$ s. The new pulsars have DMs in the range $23.6 - 133.3$ pc cm$^{-3}$ and periods in the range $1.249 - 5.012$ s, and include two nullers and a mode-switching object. We estimate an upper limit on the all-sky FRB rate of $10^5$ day$^{-1}$ for bursts with a width of 10 ms and flux density $\\gtrsim 83$ mJy. The DMs of all new discoveries are consistent with a G...

  10. Four Highly Dispersed Millisecond Pulsars Discovered in the Arecibo PALFA Galactic Plane Survey

    CERN Document Server

    Crawford, F; Lyne, A G; Stappers, B W; Nice, D J; Stairs, I H; Lazarus, P; Hessels, J W T; Freire, P C C; Allen, B; Bhat, N D R; Bogdanov, S; Brazier, A; Camilo, F; Champion, D J; Chatterjee, S; Cognard, I; Cordes, J M; Deneva, J S; Desvignes, G; Jenet, F A; Kaspi, V M; Knispel, B; Kramer, M; van Leeuwen, J; Lorimer, D R; Lynch, R; McLaughlin, M A; Ransom, S M; Scholz, P; Siemens, X; Venkataraman, A

    2012-01-01

    We present the discovery and phase-coherent timing of four highly dispersed millisecond pulsars (MSPs) from the Arecibo PALFA Galactic plane survey: PSRs J1844+0115, J1850+0124, J1900+0308, and J1944+2236. Three of the four pulsars are in binary systems with low-mass companions, which are most likely white dwarfs, and which have orbital periods on the order of days. The fourth pulsar is isolated. All four pulsars have large dispersion measures (DM > 100 pc cm-3), are distant (> 3.4 kpc), faint at 1.4 GHz (< 0.2 mJy), and are fully recycled (with spin periods P between 3.5 and 4.9 ms). The three binaries also have very small orbital eccentricities, as expected for tidally circularized, fully recycled systems with low-mass companions. These four pulsars have DM/P ratios that are among the highest values for field MSPs in the Galaxy. These discoveries bring the total number of confirmed MSPs from the PALFA survey to fifteen. The discovery of these MSPs illustrates the power of PALFA for finding weak, distant ...

  11. ARECIBO PULSAR SURVEY USING ALFA: PROBING RADIO PULSAR INTERMITTENCY AND TRANSIENTS

    International Nuclear Information System (INIS)

    We present radio transient search algorithms, results, and statistics from the ongoing Arecibo Pulsar ALFA (PALFA) survey of the Galactic plane. We have discovered seven objects through a search for isolated dispersed pulses. All of these objects are Galactic and have measured periods between 0.4 and 4.7 s. One of the new discoveries has a duty cycle of 0.01%, smaller than that of any other radio pulsar. We discuss the impact of selection effects on the detectability and classification of intermittent sources, and compare the efficiencies of periodicity and single-pulse (SP) searches for various pulsar classes. For some cases we find that the apparent intermittency is likely to be caused by off-axis detection or a short time window that selects only a few bright pulses and favors detection with our SP algorithm. In other cases, the intermittency appears to be intrinsic to the source. No transients were found with DMs large enough to require that they originate from sources outside our Galaxy. Accounting for the on-axis gain of the ALFA system, as well as the low gain but large solid-angle coverage of far-out sidelobes, we use the results of the survey so far to place limits on the amplitudes and event rates of transients of arbitrary origin.

  12. Development of Minitype UHF RFID Intelligent Handset%一种小型超高频RFID智能手持机的研制

    Institute of Scientific and Technical Information of China (English)

    左娅佳

    2012-01-01

    Objective To develop a low -cost minitype UHF RFID intelligent handset. Methods Separation electronic components were used to establish the handset with the difficulty and key techniques analyzed. Results The handset could meet the requirements of American and international UHF RFID standards, with a size of 120 mmx63 mmx20 mm, weight of 350g, output power of 28dBm, read-card distance of 1.5m and modulated frequency from 915 to 930MHz. Windows CE6.0 operation system was available. Conclusion Reasonable design and electronic components-based RFID module can result in a low-size and high-performance UHF RFID intelligent handset.%目的:研制一种低成本的小型超高频(UHF)无线射频识别(RFID)智能手持机.方法:分析UHF RFID智能手持机小型化的难点,研究使其小型化的关键技巧,提供分离电子元件构造UHF RFID智能手持机方案.结果:成功研制的超高频RFID手持机体积为120 mm×63 mm×20 mm,质量为350 g;RFID射频输出功率为28 dBm,读卡距离为1.5 m;RFID天线调频为915~930 MHz,符合UHF RFID美标及国标要求;具有Windows CE6.0操作系统.结论:通过合理设计,用电子元件构造射频模块,可制作出体积较小、性能良好的UHF RFID智能手持机.

  13. New Discoveries from the Arecibo 327 MHz Drift Pulsar Survey Radio Transient Search

    Science.gov (United States)

    Deneva, J. S.; Stovall, K.; McLaughlin, M. A.; Bagchi, M.; Bates, S. D.; Freire, P. C. C.; Martinez, J. G.; Jenet, F.; Garver-Daniels, N.

    2016-04-01

    We present Clusterrank, a new algorithm for identifying dispersed astrophysical pulses. Such pulses are commonly detected from Galactic pulsars and rotating radio transients (RRATs), which are neutron stars with sporadic radio emission. More recently, isolated, highly dispersed pulses dubbed fast radio bursts (FRBs) have been identified as the potential signature of an extragalactic cataclysmic radio source distinct from pulsars and RRATs. Clusterrank helped us discover 14 pulsars and 8 RRATs in data from the Arecibo 327 MHz Drift Pulsar Survey (AO327). The new RRATs have DMs in the range 23.5–86.6 pc cm‑3 and periods in the range 0.172–3.901 s. The new pulsars have DMs in the range 23.6–133.3 pc cm‑3 and periods in the range 1.249–5.012 s, and include two nullers and a mode-switching object. We estimate an upper limit on the all-sky FRB rate of 105 day‑1 for bursts with a width of 10 ms and flux density ≳83 mJy. The DMs of all new discoveries are consistent with a Galactic origin. In comparing statistics of the new RRATs with sources from the RRATalog, we find that both sets are drawn from the same period distribution. In contrast, we find that the period distribution of the new pulsars is different from the period distributions of canonical pulsars in the ATNF catalog or pulsars found in AO327 data by a periodicity search. This indicates that Clusterrank is a powerful complement to periodicity searches and uncovers a subset of the pulsar population that has so far been underrepresented in survey results and therefore in Galactic pulsar population models.

  14. Radar Observations of Main-Belt M-class Asteroids

    NARCIS (Netherlands)

    Shepard, Michael K.; Clark, B. E.; Ockert-Bell, M.; Nolan, M. C.; Howell, E. S.; Magri, C.; Giorgini, J. D.; Benner, L. A. M.; Ostro, S. J.; Harris, A. W.; Warner, B. D.; Stephens, R. D.; Mueller, M.

    2009-01-01

    Using the S-band radar at Arecibo Observatory, we have observed 19 Tholen M-class asteroids. The mean radar albedo for all our targets is 0.28 ± 0.13, considerably higher than the mean radar albedo of every other class (Magri et al. 2007, Icarus 186, 126-151). We find approximately one-third (six) o

  15. Disturbances in VHF/UHF telemetry links as a possible effect of the 2003 Hokkaido Tokachi-oki earthquake

    Directory of Open Access Journals (Sweden)

    H. Nagamoto

    2008-08-01

    Full Text Available The data on radio telemetry links (for water information at VHF/UHF in Hokkaido are used to investigate the rate of disturbances on radio links (or connection failure and its association with a huge earthquake, Tokachi-oki earthquake on 26 September 2003. Especially, the telemetry links at the Tokachi region closest to the earthquake epicenter, showed a significant increase in disturbances on radio links two weeks to a few days before the earthquake on the basis of analysis during a long interval from 1 June 2002 to 3 November 2007 (over 5 years. We suggest that these severe disturbances in VHF/UHF telemetry links are attributed to the generation of seismogenic VHF/UHF radio noises (emissions. Based on this idea, we have estimated that the intensity of these seismogenic emissions is on the order of 10–19 dB μV/m. Finally, the present result was compared with other physical parameters already obtained for this earthquake.

  16. In situ occupational and general public exposure to VHF/UHF transmission for air traffic communication

    International Nuclear Information System (INIS)

    Occupational and general public exposure due to very high frequency (VHF)/ultra high frequency (UHF) transmission centres for verbal communication for air traffic control is investigated in situ for the first time. These systems are used for communication with aircraft, resulting in different human exposure from that of classical broadcasting. Measurement methods are proposed for the exposure assessment, and a measurement campaign is executed in three transmission centres. By investigating the temporal behaviour of the VHF signals for 6 d, a realistic worst-case duty cycle of 29 % is determined. Periods of high exposures corresponding with high aircraft traffic are from 7 a.m. to 1 p.m. and in the evening. All measured electric field values satisfy the International Commission on Non-ionizing Radiation Protection guidelines. Fields vary from 0.2 to 21.1 V m-1 for occupational exposure and from 0.007 to 8.0 V m-1 for general public exposure. The average fields equal 5.2 V m-1 for workers, and 0.7 V m-1 for general public. (authors)

  17. A UHF RFID system with on-chip-antenna tag for short range communication

    Science.gov (United States)

    Qi, Peng; Chun, Zhang; Xijin, Zhao; Zhihua, Wang

    2015-05-01

    A UHF RF identification system based on the 0.18 μm CMOS process has been developed for short range and harsh size requirement applications, which is composed of a fully integrated tag and a special reader. The whole tag chip with the antenna takes up an area of 0.36 mm2, which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption, and minimize the size of the tag. The specialized SOC reader system consists of the RF transceiver, digital baseband, MCU and host interface. Its power consumption is about 500 mW. Measurement results show that the system's reading range is 2 mm with 20 dBm reader output power. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters, depending on the shape and size of the inductive antenna.

  18. First UHF Implementation of the Incremental Scheme for Open-Shell Systems.

    Science.gov (United States)

    Anacker, Tony; Tew, David P; Friedrich, Joachim

    2016-01-12

    The incremental scheme makes it possible to compute CCSD(T) correlation energies to high accuracy for large systems. We present the first extension of this fully automated black-box approach to open-shell systems using an Unrestricted Hartree-Fock (UHF) wave function, extending the efficient domain-specific basis set approach to handle open-shell references. We test our approach on a set of organic and metal organic structures and molecular clusters and demonstrate standard deviations from canonical CCSD(T) values of only 1.35 kJ/mol using a triple ζ basis set. We find that the incremental scheme is significantly more cost-effective than the canonical implementation even for relatively small systems and that the ease of parallelization makes it possible to perform high-level calculations on large systems in a few hours on inexpensive computers. We show that the approximations that make our approach widely applicable are significantly smaller than both the basis set incompleteness error and the intrinsic error of the CCSD(T) method, and we further demonstrate that incremental energies can be reliably used in extrapolation schemes to obtain near complete basis set limit CCSD(T) reaction energies for large systems. PMID:26605975

  19. A UHF RFID system with on-chip-antenna tag for short range communication

    International Nuclear Information System (INIS)

    A UHF RF identification system based on the 0.18 μm CMOS process has been developed for short range and harsh size requirement applications, which is composed of a fully integrated tag and a special reader. The whole tag chip with the antenna takes up an area of 0.36 mm2, which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption, and minimize the size of the tag. The specialized SOC reader system consists of the RF transceiver, digital baseband, MCU and host interface. Its power consumption is about 500 mW. Measurement results show that the system's reading range is 2 mm with 20 dBm reader output power. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters, depending on the shape and size of the inductive antenna. (paper)

  20. Near Field UHF RFID Antenna System Enabling the Tracking of Small Laboratory Animals

    Directory of Open Access Journals (Sweden)

    Luca Catarinucci

    2013-01-01

    Full Text Available Radio frequency identification (RFID technology is more and more adopted in a wide range of applicative scenarios. In many cases, such as the tracking of small-size living animals for behaviour analysis purposes, the straightforward use of commercial solutions does not ensure adequate performance. Consequently, both RFID hardware and the control software should be tailored for the particular application. In this work, a novel RFID-based approach enabling an effective localization and tracking of small-sized laboratory animals is proposed. It is mainly based on a UHF Near Field RFID multiantenna system, to be placed under the animals’ cage, and able to rigorously identify the NF RFID tags implanted in laboratory animals (e.g., mice. Once the requirements of the reader antenna have been individuated, the antenna system has been designed and realized. Moreover, an algorithm based on the measured Received Signal Strength Indication (RSSI aiming at removing potential ambiguities in data captured by the multiantenna system has been developed and integrated. The animal tracking system has been largely tested on phantom mice in order to verify its ability to precisely localize each subject and to reconstruct its path. The achieved and discussed results demonstrate the effectiveness of the proposed tracking system.

  1. UHF-Band Wireless Power Transfer System for Structural Health Monitoring Sensor Network

    Directory of Open Access Journals (Sweden)

    Tansheng Li

    2013-01-01

    Full Text Available For detecting and measuring health conditions of bridges, wireless sensor networks are used in these days. However, battery life is critically restricting the application and maintenance cost of sensor network systems. To extend life time, a wireless power transfer system at UHF band is introduced to supply the current wireless sensor network. This power transfer system is based on electric wave at 950 MHz. This power transfer system is redesigned for tiny power transmission, including a combination of a rectenna and a Cockcroft-Walton boost converter, battery board, and a control board. Also, current wireless sensor network is redesigned for power transfer system. The working flow of sensor network is modified to bottom-to-top to save power of sensor modules which are the power bottleneck of this sensor system. As a result, the system is able to support a sensor module continuously with received power of −14 dBmW, when the transmitting antenna is 30 dBmW at 10 meters distance.

  2. Preliminary exploration of the measurement of walking speed for the apoplectic people based on UHF RFID.

    Science.gov (United States)

    Huang Hua-Lin; Mo Ling-Fei; Liu Ying-Jie; Li Cheng-Yang; Xu Qi-Meng; Wu Zhi-Tong

    2015-08-01

    The number of the apoplectic people is increasing while population aging is quickening its own pace. The precise measurement of walking speed is very important to the rehabilitation guidance of the apoplectic people. The precision of traditional measuring methods on speed such as stopwatch is relatively low, and high precision measurement instruments because of the high cost cannot be used widely. What's more, these methods have difficulty in measuring the walking speed of the apoplectic people accurately. UHF RFID tag has the advantages of small volume, low price, long reading distance etc, and as a wearable sensor, it is suitable to measure walking speed accurately for the apoplectic people. In order to measure the human walking speed, this paper uses four reader antennas with a certain distance to reads the signal strength of RFID tag. Because RFID tag has different RSSI (Received Signal Strength Indicator) in different distances away from the reader, researches on the changes of RSSI with time have been done by this paper to calculate walking speed. The verification results show that the precise measurement of walking speed can be realized by signal processing method with Gaussian Fitting-Kalman Filter. Depending on the variance of walking speed, doctors can predict the rehabilitation training result of the apoplectic people and give the appropriate rehabilitation guidance. PMID:26738158

  3. A voltage regulator system with dynamic bandwidth boosting for passive UHF RFID transponders

    International Nuclear Information System (INIS)

    This paper presents a voltage regulator system for passive UHF RFID transponders, which contains a rectifier, a limiter, and a regulator. The rectifier achieves power by rectifying the incoming RF energy. Due to the huge variation of the rectified voltage, a limiter at the rectifier output is used to clamp the rectified voltage. In this paper, the design of a limiter circuit is discussed in detail, which can provide a stable limiting voltage with low sensitivity to temperature variation and process dispersion. The key aspect of the voltage regulator system is the dynamic bandwidth boosting in the regulator. By sensing the excess current that is bypassed in the limiter during periods of excess energy, the bias current as well as the bandwidth of the regulator are increased, the output supply voltage can recover quickly from line transients during the periods of no RF energy to a full blast of RF energy. This voltage regulator system is implemented in a 0.18 μm CMOS process. (semiconductor integrated circuits)

  4. A low cost integrated transceiver for mobile UHF passive RFID reader applications

    International Nuclear Information System (INIS)

    A low cost integrated transceiver for mobile UHF passive RFID reader applications is implemented in a 0.18-μm CMOS process. The transceiver contains an OOK modulator and a power amplifier in the transmitter chain, an IQ direct-down converter, variable-gain amplifiers, channel-select filters and a 10-bit ADC in the receiver chain. The measured output P1DB power of the transmitter is 17.6 dBm and the measured receiver sensitivity is -70 dBm. The on-chip integer N synthesizer achieves a frequency resolution of 200 kHz with a phase noise of -104 dBc/Hz at 100 kHz frequency offset and -120.83 dBc/Hz at 1 MHz frequency offset. The transmitter, the receiver and the frequency synthesizer consume 201.34, 25.3 and 54 mW, respectively. The chip has a die area of 4 x 2.5 mm2 including pads.

  5. Design and implementation of an ultra-low power passive UHF RFID tag

    International Nuclear Information System (INIS)

    This paper presents a fully integrated passive UHF RFID tag chip complying with the ISO18000-6B protocol. The tag chip includes an RF/analog front-end, a baseband processor, and a 512-bit EEPROM memory. To improve power conversion efficiency, a Schottky barrier diode based rectifier is adopted. A novel voltage reference using the peaking current source is discussed in detail, which can meet the low-power, low-voltage requirement while retaining circuit simplicity. Most of the analog blocks are designed to work under sub-1 V to reduce power consumption, and several practical methods are used to further reduce the power consumption of the baseband processor. The whole tag chip is implemented in a TSMC 0.18 μm CMOS process with a die size of 800 × 800 μm2. Measurement results show that the total power consumption of the tag chip is only 7.4 μW with a sensitivity of −12 dBm. (semiconductor integrated circuits)

  6. A low cost integrated transceiver for mobile UHF passive RFID reader applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jingchao; Zhang Chun; Chi Baoyong; Wang Ziqiang; Li Fule; Wang Zhihua, E-mail: wangjc@gmail.co [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2009-09-15

    A low cost integrated transceiver for mobile UHF passive RFID reader applications is implemented in a 0.18-{mu}m CMOS process. The transceiver contains an OOK modulator and a power amplifier in the transmitter chain, an IQ direct-down converter, variable-gain amplifiers, channel-select filters and a 10-bit ADC in the receiver chain. The measured output P{sub 1DB} power of the transmitter is 17.6 dBm and the measured receiver sensitivity is -70 dBm. The on-chip integer N synthesizer achieves a frequency resolution of 200 kHz with a phase noise of -104 dBc/Hz at 100 kHz frequency offset and -120.83 dBc/Hz at 1 MHz frequency offset. The transmitter, the receiver and the frequency synthesizer consume 201.34, 25.3 and 54 mW, respectively. The chip has a die area of 4 x 2.5 mm{sup 2} including pads.

  7. Enhancing the power output of the VA-955 UHF-TV klystron

    International Nuclear Information System (INIS)

    The Varian VA-955 UHF-TV klystron is rated at 50 kW CW, and four of these klystrons were used to provide 200 kW of RF power for lower hybrid heating experiments on the ATC machine at 800 MHz. These proven, production-type tubes were wanted to generate more power for larger type machines, such as the PDX. Varian was asked whether the tubes were capable of higher-power operation in pulsed applications. They replied that they had no experimental data but felt that the tubes were capable of greatly enhanced performance under pulsed conditions. By using cathode modulation instead of modulating anode control of the klystron, and thus limiting the time that high voltage is applied to the cathode, it was shown that the tube is capable of an output power of 200 kW for tens of milliseconds compared to its normal CW rating of 50 kW. A description is given of the experimental results, the required modifications to the klystron and output transmission circuit, the details of operation of the regulating modulator used to perform the experiment. Upgrade kits are now being fabricated to allow 200 kW operation of the two 50 kW units which were lent to General Atomic for Doublet II experiments

  8. SPATIAL VARIABILITY OF VHF/UHF ELECTRIC FIELD STRENGTH IN NIGER STATE, NIGERIA

    Directory of Open Access Journals (Sweden)

    Moses Oludare Ajewole

    2014-03-01

    Full Text Available This study investigates the coverage areas of VHF and UHF signals from three television stations in Niger State, Nigeria, by quantitatively measuring the signal levels of these signals. The signal levels of the transmitters of Nigeria Television Authority (NTA, Minna, Channel 10, (210.25 MHz; NTA, Kotangora, Channel 8, (196.25 MHz and Niger State Television, Minna, Channel 25, (503.25 MHz, and the corresponding distances were measured along some radial routes with the transmitting stations at focus. These measurements were taken using Digital Signal Level Meter and Global Positioning System (GPS. From the data obtained, Surfer 8 software application was used to draw contour maps of the signal levels around the transmitting stations to determine the coverage areas of the stations. The results obtained show that the present configurations of the transmitters of the three television stations do not give an optimal coverage of the state. Only 25.82% of the entire land mass of the state has television signal coverage. Consequently, greater percentage of Niger State is completely out of television signal coverage. So, there is need to have repeater stations at some intervals to ensure reception of television signals throughout the state.

  9. Design and Performance Evaluation of Two-Unit YAGI-UDA Array for UHF Satellite Communication

    Directory of Open Access Journals (Sweden)

    Rupesh Lad

    2014-11-01

    Full Text Available Cube satellite missions perform innovative scientif ic experiments on a low cost developmental platform but have an inherent limitation of size and space. This restricts the total available solar power that can be harnessed and as a result, the radio links operate on stringent power budgets. For improving the avail able margins for communication in such satellites, it is desirable to improve upon the antenna system performance at the ground station used for the esta blishment of the links with the satellite. This can be achieved by improving the forward gain, the forward to backward ratio and the directivity of the anten na. This paper describes the electrical simulations and the performance evaluation of the one unit, two un it and four unit circularly polarized crossed Yagi-Uda ant enna array designed for communication with amateur radio (HAM satellites operating over the 434 MHz t o 438 MHz Amateur UHF band. The electro-magnetic model has been developed using the 4NEC2 software. The simulations have been validated with the practical field testing performed for estimating th e SWR, antenna gain, the forward to backward ratio and radiation pattern for the antenna system

  10. Design of planar electron gun for UHF range, CW power inductive output tube

    International Nuclear Information System (INIS)

    Inductive Output Tube (lOT) is an amplifier which is now-a-days in demand for scientific applications. For every vacuum tube, electron gun is an important part and in fact considered as the heart of the tube. Hence, designing of this component is very crucial for efficient operation of the device throughout its lifetime. This paper is all about the electromagnetic (EM) design of planar electron gun of 40 kV, 3.5 A beam voltage and beam current respectively, for a 100 kW CW power lOT operating in UHF range. The design considerations and basic equations involved in its design are included in the paper. The gun structure has been optimized for getting the desired beam characteristics. The simulation results including the beam profile along with the beam current are shown using two commercial codes namely TRAK and MAGIC code. Planar shape of electron beam reduces space charge forces in the beam itself and consequently beam energy spread for a given current. The magnetic focusing of planar beam is easier comparative to spherical beam hence, this structure has been adopted for this particular device design. (author)

  11. Design and implementation of a high sensitivity fully integrated passive UHF RFID tag

    International Nuclear Information System (INIS)

    A fully integrated passive UHF RFID tag complying with the ISO18000-6B protocol is presented, which includes an analog front-end, a baseband processor, and an EEPROM memory. To extend the communication range, a high efficiency differential-drive CMOS rectifier is adopted. A novel high performance voltage limiter is used to provide a stable limiting voltage, with a 172 mV voltage variation against temperature variation and process dispersion. The dynamic band-enhancement technique is used in the regulator circuit to improve the regulating capacity. A rail-to-rail hysteresis comparator is adopted to demodulate the signal correctly in any condition. The whole transponder chip is implemented in a 0.18 μm CMOS process, with a die size of 900 × 800 μm2. Our measurement results show that the total power consumption of the tag chip is only 6.8 μW, with a sensitivity of −13.5 dBm (semiconductor integrated circuits)

  12. A low cost integrated transceiver for mobile UHF passive RFID reader applications

    Science.gov (United States)

    Jingchao, Wang; Chun, Zhang; Baoyong, Chi; Ziqiang, Wang; Fule, Li; Zhihua, Wang

    2009-09-01

    A low cost integrated transceiver for mobile UHF passive RFID reader applications is implemented in a 0.18-μm CMOS process. The transceiver contains an OOK modulator and a power amplifier in the transmitter chain, an IQ direct-down converter, variable-gain amplifiers, channel-select filters and a 10-bit ADC in the receiver chain. The measured output P1DB power of the transmitter is 17.6 dBm and the measured receiver sensitivity is -70 dBm. The on-chip integer N synthesizer achieves a frequency resolution of 200 kHz with a phase noise of -104 dBc/Hz at 100 kHz frequency offset and -120.83 dBc/Hz at 1 MHz frequency offset. The transmitter, the receiver and the frequency synthesizer consume 201.34, 25.3 and 54 mW, respectively. The chip has a die area of 4 × 2.5 mm2 including pads.

  13. Design and implementation of a high sensitivity fully integrated passive UHF RFID tag

    Science.gov (United States)

    Shoucheng, Li; Xin'an, Wang; Ke, Lin; Jinpeng, Shen; Jinhai, Zhang

    2014-10-01

    A fully integrated passive UHF RFID tag complying with the ISO18000-6B protocol is presented, which includes an analog front-end, a baseband processor, and an EEPROM memory. To extend the communication range, a high efficiency differential-drive CMOS rectifier is adopted. A novel high performance voltage limiter is used to provide a stable limiting voltage, with a 172 mV voltage variation against temperature variation and process dispersion. The dynamic band-enhancement technique is used in the regulator circuit to improve the regulating capacity. A rail-to-rail hysteresis comparator is adopted to demodulate the signal correctly in any condition. The whole transponder chip is implemented in a 0.18 μm CMOS process, with a die size of 900 × 800 μm2. Our measurement results show that the total power consumption of the tag chip is only 6.8 μW, with a sensitivity of -13.5 dBm

  14. VHF/UHF UWB SAR基于通道均衡的RFI抑制方法%A RFI Suppression Algorithm Based on Channel Equalization for the VHF/UHF UWB SAR

    Institute of Scientific and Technical Information of China (English)

    董臻; 梁甸农; 黄晓涛

    2008-01-01

    对工作于甚高频/超高频(VHF/UHF)波段的超宽带合成孔径雷达(UWB SAR),射频干扰(RFI)会严重恶化图像质量.该文提出了一种基于通道均衡的RFI抑制方法,它能有效地抑制雷达接收信号中的RFI分量,同时保持图像质量.实际的处理结果证实了该算法的有效性.

  15. Comparison of Phase-Based 3D Near-Field Source Localization Techniques for UHF RFID

    Science.gov (United States)

    Parr, Andreas; Miesen, Robert; Vossiek, Martin

    2016-01-01

    In this paper, we present multiple techniques for phase-based narrowband backscatter tag localization in three-dimensional space with planar antenna arrays or synthetic apertures. Beamformer and MUSIC localization algorithms, known from near-field source localization and direction-of-arrival estimation, are applied to the 3D backscatter scenario and their performance in terms of localization accuracy is evaluated. We discuss the impact of different transceiver modes known from the literature, which evaluate different send and receive antenna path combinations for a single localization, as in multiple input multiple output (MIMO) systems. Furthermore, we propose a new Singledimensional-MIMO (S-MIMO) transceiver mode, which is especially suited for use with mobile robot systems. Monte-Carlo simulations based on a realistic multipath error model ensure spatial correlation of the simulated signals, and serve to critically appraise the accuracies of the different localization approaches. A synthetic uniform rectangular array created by a robotic arm is used to evaluate selected localization techniques. We use an Ultra High Frequency (UHF) Radiofrequency Identification (RFID) setup to compare measurements with the theory and simulation. The results show how a mean localization accuracy of less than 30 cm can be reached in an indoor environment. Further simulations demonstrate how the distance between aperture and tag affects the localization accuracy and how the size and grid spacing of the rectangular array need to be adapted to improve the localization accuracy down to orders of magnitude in the centimeter range, and to maximize array efficiency in terms of localization accuracy per number of elements. PMID:27347976

  16. Comparison of Phase-Based 3D Near-Field Source Localization Techniques for UHF RFID

    Directory of Open Access Journals (Sweden)

    Andreas Parr

    2016-06-01

    Full Text Available In this paper, we present multiple techniques for phase-based narrowband backscatter tag localization in three-dimensional space with planar antenna arrays or synthetic apertures. Beamformer and MUSIC localization algorithms, known from near-field source localization and direction-of-arrival estimation, are applied to the 3D backscatter scenario and their performance in terms of localization accuracy is evaluated. We discuss the impact of different transceiver modes known from the literature, which evaluate different send and receive antenna path combinations for a single localization, as in multiple input multiple output (MIMO systems. Furthermore, we propose a new Singledimensional-MIMO (S-MIMO transceiver mode, which is especially suited for use with mobile robot systems. Monte-Carlo simulations based on a realistic multipath error model ensure spatial correlation of the simulated signals, and serve to critically appraise the accuracies of the different localization approaches. A synthetic uniform rectangular array created by a robotic arm is used to evaluate selected localization techniques. We use an Ultra High Frequency (UHF Radiofrequency Identification (RFID setup to compare measurements with the theory and simulation. The results show how a mean localization accuracy of less than 30 cm can be reached in an indoor environment. Further simulations demonstrate how the distance between aperture and tag affects the localization accuracy and how the size and grid spacing of the rectangular array need to be adapted to improve the localization accuracy down to orders of magnitude in the centimeter range, and to maximize array efficiency in terms of localization accuracy per number of elements.

  17. Comparison of Phase-Based 3D Near-Field Source Localization Techniques for UHF RFID.

    Science.gov (United States)

    Parr, Andreas; Miesen, Robert; Vossiek, Martin

    2016-01-01

    In this paper, we present multiple techniques for phase-based narrowband backscatter tag localization in three-dimensional space with planar antenna arrays or synthetic apertures. Beamformer and MUSIC localization algorithms, known from near-field source localization and direction-of-arrival estimation, are applied to the 3D backscatter scenario and their performance in terms of localization accuracy is evaluated. We discuss the impact of different transceiver modes known from the literature, which evaluate different send and receive antenna path combinations for a single localization, as in multiple input multiple output (MIMO) systems. Furthermore, we propose a new Singledimensional-MIMO (S-MIMO) transceiver mode, which is especially suited for use with mobile robot systems. Monte-Carlo simulations based on a realistic multipath error model ensure spatial correlation of the simulated signals, and serve to critically appraise the accuracies of the different localization approaches. A synthetic uniform rectangular array created by a robotic arm is used to evaluate selected localization techniques. We use an Ultra High Frequency (UHF) Radiofrequency Identification (RFID) setup to compare measurements with the theory and simulation. The results show how a mean localization accuracy of less than 30 cm can be reached in an indoor environment. Further simulations demonstrate how the distance between aperture and tag affects the localization accuracy and how the size and grid spacing of the rectangular array need to be adapted to improve the localization accuracy down to orders of magnitude in the centimeter range, and to maximize array efficiency in terms of localization accuracy per number of elements. PMID:27347976

  18. Using UHF proximity loggers to quantify male-female interactions: a scoping study of estrous activity in cattle.

    Science.gov (United States)

    O'Neill, C J; Bishop-Hurley, G J; Williams, P J; Reid, D J; Swain, D L

    2014-12-10

    Reproductive efficiency is an important determinant of profitable cattle breeding systems and the success of assisted reproductive techniques (ART) in wildlife conservation programs. Methods of estrous detection used in intensive beef and dairy cattle systems lack accuracy and remain the single biggest issue for improvement of reproductive rates and such methods are not practical for either large-scale extensive beef cattle enterprises or free-living mammalian species. Recent developments in UHF (ultra high frequency) proximity logger telemetry devices have been used to provide a continuous pair-wise measure of associations between individual animals for both livestock and wildlife. The objective of this study was to explore the potential of using UHF telemetry to identify the reproductive cycle phenotype in terms of intensity and duration of estrus. The study was conducted using Belmont Red (interbred Africander Brahman Hereford-Shorthorn) cattle grazing irrigated pasture on Belmont Research Station, northeastern Australia. The cow-bull associations from three groups of cows each with one bull were recorded over a 7-week breeding season and the stage of estrus was identified using ultrasonography. Telemetry data from bull and cows, collected over 4 8-day logger deployments, were log transformed and analyzed by ANOVA. Both the number and duration of bull-cow affiliations were significantly (P<0.001) greater in estrous cows compared to anestrus cows. These results support the development of the UHF technology as a hands-off and noninvasive means of gathering socio-sexual information on both wildlife and livestock for reproductive management. PMID:25449547

  19. Persistent enhancement of the HF pump-induced plasma line measured with a UHF diagnostic radar at HAARP

    OpenAIRE

    Oyama, S.; B. J. Watkins; Djuth, F.T.; Kosch, Mike J.; Bernhardt, P. A.; Heinselman, C. J.

    2006-01-01

    Plasma lines excited by a powerful, high-frequency (HF) radio wave are studied using data obtained with an ultrahigh frequency (UHF) radar at HAARP (High Frequency Active Auroral Research Program) from 3 to 5 February 2005. Of particular interest is persistent enhancement of the radar backscatter power during HF on at several HF frequencies. The persistent enhancement is induced with the HF frequency slightly lower than foF2 by a few hundred kHz; by contrast the persistent enhancement does no...

  20. Decrease of the effect of ionizing radiation by the differential heating of tissues by UHF-field

    International Nuclear Information System (INIS)

    The differential heating (35-43.5 deg C, 30 min) of sarcoma 45 causes an increase of its growth due to the growth of the tumour regions uneffected by the damaging temperature and having the temperature comparable to the normal temperature of experimental animal. The differential heating just after γ-irradiation decreases the damaging effect of ionizing radiation on tumour tissue, or to be more precise, on the tumour regions with subhypothermal temperature. Possible bioenergetic mechanisms of the trophic and radioprotective effects at differential heating of tumours by the electric UHF-field are discussed

  1. Influence of inherent parameter of stabilized UHF oscillators on autodyne response formation at a strong reflected signal

    Directory of Open Access Journals (Sweden)

    Noskov V. Ya.

    2011-08-01

    Full Text Available Results of an autodyne response analysis in UHF oscillators stabilized by the external high-Q cavity in the case of the strong signal when the reflected wave amplitude commen-surable with the own oscillation amplitude. Coupling between the basic operation cavity and the stabilizing cavity is implemented as a pass-reflecting filter with a resistive bond. Key relations are obtained, which describe the autodyne response to the own re-reflected radiation from a target. The load and oscillating system influence on autodyne response formation is fulfilled.

  2. Comparative Method for Indirect Sensitivity Measurement of UHF RFID Reader with Respect to Interoperability and Conformance Requirements

    Directory of Open Access Journals (Sweden)

    Lukas Kypus

    2014-01-01

    Full Text Available There is never-ending race for the competitive advantage that forces RFID technology service integrators to focus more on used technology qualitative aspects and theirs impacts inside RFID ecosystem. This paper contributes to UHF RFID reader qualitative parameters evaluation and assessment problematic. It presents and describes in details indirect method and procedure of sensitivity measurement created for UHF RFID readers. We applied this method on RFID readers within prepared test environment and confirmed long term intention and recognized trend. Due to regulations limitations, there is not possible to increase output power over defined limits, but there are possibilities to influence reader sensitivity. Our proposal is to use customized comparative measurement method with insertion loss compensation for return link. Beside the main goal achievement, results show as well the qualitative status of development snapshot of reader. Method and following experiment helped us to gain an external view, current values of important parameters and motivation we want to follow up on as well as compared developed reader with its commercial competitors.

  3. Van Allen Probe measurements of the electric drift E × B/B2 at Arecibo's L = 1.4 field line coordinate

    Science.gov (United States)

    Lejosne, Solène; Mozer, F. S.

    2016-07-01

    We have used electric and magnetic measurements by Van Allen Probe B from 2013 to 2014 to examine the equatorial electric drift E × B/B2 at one field line coordinate set to Arecibo's incoherent scatter radar location (L = 1.43). We report on departures from the traditional picture of corotational motion with the Earth in two ways: (1) the rotational angular speed is found to be 10% smaller than the rotational angular speed of the Earth, in agreement with previous works on plasmaspheric notches, and (2) the equatorial electric drift displays a dependence in magnetic local time, with a pattern consistent with the mapping of the Arecibo ionosphere dynamo electric fields along equipotential magnetic field lines. The electric fields due to the ionosphere dynamo are therefore expected to play a significant role when discussing, for instance, the structure and dynamics of the plasmasphere or the transport of trapped particles in the inner belt.

  4. Design and Optimization of Passive UHF RFID Tag Antenna for Mounting on or inside Material Layers

    Science.gov (United States)

    Shao, Shuai

    There is great desire to employ passive UHF RFID tags for inventory tracking and sensing in a diversity of applications and environments. Owing to its battery-free operation, non-line-of sight detection, low cost, long read range and small form factor, each year billions of RFID tags are being deployed in retail, logistics, manufacturing, biomedical inventories, among many other applications. However, the performance of these RFID systems has not met expectations. This is because a tag's performance deteriorates significantly when mounted on or inside arbitrary materials. The tag antenna is optimized only for a given type of material at a certain location of placement, and detuning takes place when attached to or embedded in materials with dielectric properties outside the design range. Thereby, different customized tags may be needed for identifying objects even within the same class of products. This increases the overall cost of the system. Furthermore, conventional copper foil-based RFID tag antennas are prone to metal fatigue and wear, and cannot survive hostile environments where antennas could be deformed by external forces and failures occur. Therefore, it is essential to understand the interaction between the antenna and the material in the vicinity of the tag, and design general purpose RFID tag antennas possessing excellent electrical performance as well as robust mechanical structure. A particularly challenging application addressed here is designing passive RFID tag antennas for automotive tires. Tires are composed of multiple layers of rubber with different dielectric properties and thicknesses. Furthermore, metallic plies are embedded in the sidewalls and steel belts lie beneath the tread to enforce mechanical integrity. To complicate matters even more, a typical tire experiences a 10% stretching during the construction process. This dissertation focuses on intuitively understanding the interaction between the antenna and the material in the

  5. A current-mode voltage regulator with an embedded sub-threshold reference for a passive UHF RFID transponder

    International Nuclear Information System (INIS)

    This paper presents a current-mode voltage regulator for a passive UHF RFID transponder. The passive tag power is extracted from RF energy through the RF-to-DC rectifier. Due to huge variations of the incoming RF power, the rectifier output voltage should be regulated to achieve a stable power supply. By accurately controlling the current flowing into the load with an embedded sub-threshold reference, the regulated voltage varies in a range of 1-1.3 V from -20 to 80 0C, and a bandwidth of about 100 kHz is achieved for a fast power recovery. The circuit is fabricated in UMC 0.18 μm mixed-mode CMOS technology, and the current consumption is only 1 μA. (semiconductor integrated circuits)

  6. A current-mode voltage regulator with an embedded sub-threshold reference for a passive UHF RFID transponder

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhongqi [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China); Zhang Chun; Li Yongming; Wang Zhihua, E-mail: liu-zq04@mails.tsinghua.edu.c [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2010-06-15

    This paper presents a current-mode voltage regulator for a passive UHF RFID transponder. The passive tag power is extracted from RF energy through the RF-to-DC rectifier. Due to huge variations of the incoming RF power, the rectifier output voltage should be regulated to achieve a stable power supply. By accurately controlling the current flowing into the load with an embedded sub-threshold reference, the regulated voltage varies in a range of 1-1.3 V from -20 to 80 {sup 0}C, and a bandwidth of about 100 kHz is achieved for a fast power recovery. The circuit is fabricated in UMC 0.18 {mu}m mixed-mode CMOS technology, and the current consumption is only 1 {mu}A. (semiconductor integrated circuits)

  7. New Radio Telescope Makes First Scientific Observations

    Science.gov (United States)

    2001-05-01

    first since Magellan to cover large areas of the planet's surface, will provide images showing surface features as small as about 1 km (3,000 ft), only three times the size of the Arecibo telescope itself. Venus may be a geologically active planet similar to the Earth, and the new images will be used to look for changes on Venus due to volcanic activity, landslides and other processes that may have modified the surface since the Magellan mission. The radar echoes received by both telescopes also can be combined to form a radar interferometer capable of measuring altitudes over some of the planet's mountainous regions with considerably better detail than was achieved by Magellan. These were the first scheduled observations with the new Robert C. Byrd Green Bank Telescope, demonstrating its capabilities for solar-system studies. In addition to the observations of Venus, a tiny 150m (500 ft) asteroid, 2001 EC16, was imaged with the two telescopes working as a combined radar system on March 26 when the asteroid was only 8 times the distance of the Moon from the Earth. The image could show details on the asteroid's surface only 15 meters (50 ft) in size and shows EC16 to be an irregularly shaped object rotating about once every 200 hrs, one of the slowest rotation rates so far measured for these objects. It took about 20 seconds for the radar signal to go to EC16 and back, compared with the almost 5 minutes needed to go to Venus and back. EC16 was discovered by the NEAT asteroid survey on March 15, 11 days prior to the radar observations. Very large numbers of these near-Earth asteroids are being discovered and the combined Arecibo-GBT radar system will be needed to properly study a significant number of them. The Robert C. Byrd Green Bank Telescope The observing team led by Campbell also included Jean-Luc Margot of Caltech, Lynn Carter of Cornell, and Bruce Campbell of the Smithsonian Institution. The 100-meter (330 feet) Robert C. Byrd Green Bank Telescope was dedicated in

  8. The Arecibo Legacy Fast ALFA Survey: X. The HI Mass Function and Omega_HI From the 40% ALFALFA Survey

    CERN Document Server

    Martin, Ann M; Giovanelli, Riccardo; Haynes, Martha P; Springob, Christopher M; Stierwalt, Sabrina

    2010-01-01

    The Arecibo Legacy Fast ALFA (ALFALFA) survey has completed source extraction for 40% of its total sky area, resulting in the largest sample of HI-selected galaxies to date. We measure the HI mass function from a sample of 10,119 galaxies with 6.2 < log (M_HI/M_Sun) < 11.0 and with well-described mass errors that accurately reflect our knowledge of low-mass systems. We characterize the survey sensitivity and its dependence on profile velocity width, the effect of large-scale structure, and the impact of radio frequency interference in order to calculate the HIMF with both the 1/Vmax and 2DSWML methods. We also assess a flux-limited sample to test the robustness of the methods applied to the full sample. These measurements are in excellent agreement with one another; the derived Schechter function parameters are phi* = 4.8 (+/- 0.3) * 10^-3, log (M*/M_Sun) + 2 log(h_70) = 9.96 (+/- 0.2), and alpha = -1.33 (+/- 0.02). We find Omega_HI = 4.3 (+/- 0.3) * 10^-4, 16% larger than the 2005 HIPASS result, and ou...

  9. Climatology of the O+ temperatures over Arecibo for the historical deep solar minimum using Incoherent Scatter Radar and airglow data.

    Science.gov (United States)

    Santos, P. T.; Brum, C. G. M.; Kerr, R.; Noto, J.

    2014-12-01

    At Arecibo Observatory (AO) a comprehensive description of the ionosphere and thermosphere environment is achieved by the synergy between the Incoherent Scatter Radar (ISR) and the optical instruments nested on site. An example of this synergy is present in his work where optical and radar techniques were reconciled in order to obtain the O+ temperature variability for 2008 and 2009. During this period, a historical deep solar minimum condition was registered with a remarkable absence of sunspots for a long period (translated into a decreasing in the EUV-UV irradiance). This particular feature implies in an important tool to investigate the variability of O+ temperature, once that any variation can be related to season (modulated by the neutral atmosphere) and/or another modulator different than solar energy input. The OII 7320 Å twilight airglow data used in this work were obtained during new moon periods using a high-spectral resolution Fabry-Perot Interferometer (FPI) with CCD array detection. The FPI was configured with 0.9 cm plate spacing, which produced a free spectral range of 0.298Å and a spectral resolution of 0.03Å, sufficient to sample line width temperatures as low as 500K. A very narrow 3Å Full Width at Half Maximum (FWHM) three-cavity interference filter was also used.

  10. GOALS, STRATEGIES AND FIRST DISCOVERIES OF AO327, THE ARECIBO ALL-SKY 327 MHz DRIFT PULSAR SURVEY

    International Nuclear Information System (INIS)

    We report initial results from AO327, a drift survey for pulsars with the Arecibo telescope at 327 MHz. The first phase of AO327 will cover the sky at declinations of –1° to 28°, excluding the region within 5° of the Galactic plane, where high scattering and dispersion make low-frequency surveys sub-optimal. We record data from a 57 MHz bandwidth with 1024 channels and 125 μs sampling time. The 60 s transit time through the AO327 beam means that the survey is sensitive to very tight relativistic binaries even with no acceleration searches. To date we have detected 44 known pulsars with periods ranging from 3 ms to 2.21 s and discovered 24 new pulsars. The new discoveries include 3 ms pulsars, three objects with periods of a few tens of milliseconds typical of young as well as mildly recycled pulsars, a nuller, and a rotating radio transient. Five of the new discoveries are in binary systems. The second phase of AO327 will cover the sky at declinations of 28°-38°. We compare the sensitivity and search volume of AO327 to the Green Bank North Celestial Cap survey and the GBT350 drift survey, both of which operate at 350 MHz

  11. Geology and tectonics of Beta Regio, Guinevere Planitia, Sedna Planitia, and Western Eistla Regio, Venus - Results from Arecibo image data

    Science.gov (United States)

    Senske, D. A.; Fisher, P. C.; Head, J. W.; Aubele, J. C.; Campbell, D. B.; Stacy, N.; Stofan, E. R.; Hine, A. A.; Harmon, J. K.

    1991-01-01

    The geology of a portion of the equatorial region of Venus (1 deg S to 45 deg N and from 270 deg eastward to 30 deg) is assessed on the basis of new radar images obtained from the Arecibo Observatory. Nine geologic units are mapped on the basis of their radar characteristics, and their distribution and correspondences with topography are examined. Plains are the most abundant unit, comprising 80 percent of the area imaged, and are divided into bright, dark, and mottled. Mottled plains contain abundant lava flows and domes, suggesting that volcanism forming planes is a significant process in the equatorial region of Venus. Tesserae are found primarily on Beta Regio and its eastern flank and are interpreted to be locally stratigraphically older units, predating episodes of faulting and plains formation. On the basis of spatial and temporal relationships between geologic units, the highlands of Beta Regio and Western Eistla Regio are interpreted to have formed in association with areas of mantle upwelling which uplift plains, cause rifting, and, in the case of Beta Regio, disrupt a large region of tesserae.

  12. A New Vision for Smart Objects and the Internet of Things: Mobile Robots and Long-Range UHF RFID Sensor Tags

    OpenAIRE

    Wang, Jennifer; Schluntz, Erik; Otis, Brian; Deyle, Travis

    2015-01-01

    We present a new vision for smart objects and the Internet of Things wherein mobile robots interact with wirelessly-powered, long-range, ultra-high frequency radio frequency identification (UHF RFID) tags outfitted with sensing capabilities. We explore the technology innovations driving this vision by examining recently-commercialized sensor tags that could be affixed-to or embedded-in objects or the environment to yield true embodied intelligence. Using a pair of autonomous mobile robots out...

  13. A dual-mode secure UHF RFID tag with a crypto engine in 0.13-μm CMOS

    Science.gov (United States)

    Tao, Yang; Linghao, Zhu; Xi, Tan; Junyu, Wang; Lirong, Zheng; Hao, Min

    2016-07-01

    An ultra-high-frequency (UHF) radio frequency identification (RFID) secure tag chip with a non-crypto mode and a crypto mode is presented. During the supply chain management, the tag works in the non-crypto mode in which the on-chip crypto engine is not enabled and the tag chip has a sensitivity of ‑12.8 dBm for long range communication. At the point of sales (POS), the tag will be switched to the crypto mode in order to protect the privacy of customers. In the crypto mode, an advanced encryption standard (AES) crypto engine is enabled and the sensitivity of the tag chip is switched to +2 dBm for short range communication, which is a method of physical protection. The tag chip is implemented and verified in a standard 0.13-μm CMOS process. Project supported by the National Science & Technology Pillar Program of China (No. 2015BAK36B01).

  14. Application of HFCT and UHF Sensors in On-Line Partial Discharge Measurements for Insulation Diagnosis of High Voltage Equipment

    Directory of Open Access Journals (Sweden)

    Fernando Álvarez

    2015-03-01

    Full Text Available Partial discharge (PD measurements provide valuable information for assessing the condition of high voltage (HV insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS compartment.

  15. A 900 MHz fractional-N synthesizer for UHF transceiver in 0.18 μm CMOS technology

    International Nuclear Information System (INIS)

    A 900 MHz fractional-N synthesizer is designed for the UHF transceiver. The VCO with a 4 bits capacitor bank covers 823–1061 MHz that implements 16 (24) sub-bands. A 7/8 dual-modulus prescaler is implemented with a phase-switching circuit and high-speed flip—flops, which are composed of source coupled logic. The proposed synthesizer phase-locked loop is demonstrated with a 50 kHz band width by a low 12.95 MHz reference clock, and offers a better phase noise and band width tradeoff. To reduce the out-band phase noise, a 4-levels 3-order single-loop sigma—delta modulator is applied. When its relative frequency resolution is settled to 10−6, the testing results show that the phase noises are −120.6 dBc/Hz at 1 MHz and −95.0 dBc/Hz at 100 kHz. The chip is 2.1 mm2 in UMC 0.18 μm CMOS. The power is 36 mW at a 1.8 V supply. (semiconductor integrated circuits)

  16. The Arecibo Legacy Fast ALFA Survey: The alpha.40 HI Source Catalog, its Characteristics and their Impact on the Derivation of the HI Mass Function

    CERN Document Server

    Haynes, Martha P; Martin, Ann M; Hess, Kelley M; Saintonge, Amelie; Adams, Elizabeth A K; Hallenbeck, Gregory; Hoffman, G Lyle; Huang, Shan; Kent, Brian R; Koopmann, Rebecca A; Papastergis, Emmanouil; Stierwalt, Sabrina; Balonek, Thomas J; Craig, David W; Higdon, Sarah J U; Kornreich, David A; Miller, Jeffrey R; O'Donoghue, Aileen A; Olowin, Ronald P; Rosenberg, Jessica L; Spekkens, Kristine; Troischt, Parker; Wilcots, Eric M

    2011-01-01

    We present a current catalog of 21 cm HI line sources extracted from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey over ~2800 square degrees of sky: the alpha.40 catalog. Covering 40% of the final survey area, the alpha.40 catalog contains 15855 sources in the regions 07h30m < R.A. < 16h30m, +04 deg < Dec. < +16 deg and +24 deg < Dec. < +28 deg and 22h < R.A. < 03h, +14 deg < Dec. < +16 deg and +24 deg < Dec. < +32 deg. Of those, 15041 are certainly extragalactic, yielding a source density of 5.3 galaxies per square degree, a factor of 29 improvement over the catalog extracted from the HI Parkes All Sky Survey. In addition to the source centroid positions, HI line flux densities, recessional velocities and line widths, the catalog includes the coordinates of the most probable optical counterpart of each HI line detection, and a separate compilation provides a crossmatch to identifications given in the photometric and spectroscopic catalogs associated wi...

  17. arecibo.grd

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission...

  18. A comparison of EISCAT and HF Doppler observations of a ULF wave

    OpenAIRE

    Wright, D. M.; Yeoman, T.K.; Davies, J. A.

    1998-01-01

    Since the middle of 1995, an HF Doppler sounder has been running almost continuously in northern Norway, with the receiver at Ramfjordmoen and the transmitter at Seljelvnes. Concurrent operation of the EISCAT UHF radar in common programme (CP-1) mode has made it possible to study the ionospheric signature of a magnetospheric ULF wave. These are the first results of such wave signatures observed simultaneously in both instruments. It has been demonstrated that the observed Doppler signature wa...

  19. Calibration of UHF Sensors for GIS: Comparison of Different Methods and Testing of a Calibration System Based on a Conical Antenna%Calibration of UHF Sensors for GIS: Comparison of Different Methods and Testing of a Calibration System Based on a Conical Antenna

    Institute of Scientific and Technical Information of China (English)

    David Gautschi; Pierre Bertholet

    2011-01-01

    Different methods of calibrating ultra high frequency(UHF) sensors for gas-insulated substations (GIS) were investigated in the past. The first approach was to use strip lines, triplates and TEM calibration cells. These cells had already been in use for years for example to test the electromagnetic compatibility of electronic devices. The smaller the size of the cell, the higher its bandwidth-but the cell should be large enough to not disturb the electric field with the installed sensor under test. To overcome this problem, a calibration procedure using a gigahertz transverse e- lectromagnetic(GTEM) test cell and a pulsed signal source were introduced in 1997. Although this procedure has many advantages and is easy to understand, measurements show several shortcomings of this calibration method. To overcome the disadvantages of the known systems, a calibration cell using a monopole cone antenna and a metallic ground plane were developed and tested. The UHF sensor was placed in a region with minimum distortion of the elec- tric field due to its installation. Experience shows that the new method for calibrating UHF sensors is necessary in or- der to overcome the limits in the calibration of large sensors and to suppress the propagation of higher order modes and reflections. Due to its surprisingly simple structure, its low price and low overall measurement uncertainty, it is the preferred method for calibrating UHF sensors for GIS applications.

  20. Extending ALFALFA: Reducing L-Band Wide Observations of Optically Selected Galaxies

    Science.gov (United States)

    Smith, Evan; O'Donoghue, Aileen A.; Haynes, Martha P.; Koopmann, Rebecca A.; Undergraduate ALFALFA Team

    2016-01-01

    Observations of galaxies in the Virgo Cluster were completed at the Arecibo Observatory in the spring and summer of 2015. 161 targets were observed, selected by photometry criteria such as magnitude and shape from the Sloan Digital Sky Survey. The targets, some too dim to be detected by Arecibo's ALFA drift scanner, were observed with the L-Band Wide detector. Once reductions in an IDL environment were done, these data were matched to the targets from the Sloan Digital Sky Survey and the GALEX/MAST catalog. 115 of the 161 targets observed had positive detections, a 71% success rate. Comparing the galaxies that were detected against the galaxies that were not detected (by the L-Band Wide receiver) will allow us to refine our method of using photometric data to select HI-rich galaxies in the 2000 km/s to 9000 km/s range to refine our selection for the Arecibo Pisces-Perseus Supercluster Survey (APPSS), which uses the same method of target selection.

  1. Generation of ionospheric ducts by the HAARP HF heater

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, J A; Pradipta, R; Burton, L M; Labno, A; Lee, M C [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Watkins, B J; Fallen, C [University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Kuo, S P [New York University, Brooklyn, NY 11201 (United States); Burke, W J [Air Force Research Laboratory, Hanscom AFB, MA 01731 (United States); Mabius, D; See, B Z, E-mail: mclee@mit.edu [Boston University, Boston, MA 02215 (United States)

    2010-12-15

    We report an investigation of ionospheric ducts having the shape of large plasma sheets, generated by vertically transmitted HAARP HF heater waves in several experiments conducted in Gakona, Alaska. Theory predicts that O-mode heater wave-created ionospheric ducts form parallel-plate waveguides within the meridional plane, and those generated by the X-mode heater waves are orthogonal to the meridional plane. Our theoretical prediction is supported by measurements of ionosonde data (namely ionograms), range-time-intensity (RTI) plots of UHF and HF backscatter radars, as well as magnetometer data analyses. When these plasma sheets experienced ExB drifts, they were intercepted by the HAARP UHF radar and seen as slanted stripes in the RTI plots. This striking feature was also observed in our earlier experiments using the Arecibo UHF radar.

  2. Generation of ionospheric ducts by the HAARP HF heater

    International Nuclear Information System (INIS)

    We report an investigation of ionospheric ducts having the shape of large plasma sheets, generated by vertically transmitted HAARP HF heater waves in several experiments conducted in Gakona, Alaska. Theory predicts that O-mode heater wave-created ionospheric ducts form parallel-plate waveguides within the meridional plane, and those generated by the X-mode heater waves are orthogonal to the meridional plane. Our theoretical prediction is supported by measurements of ionosonde data (namely ionograms), range-time-intensity (RTI) plots of UHF and HF backscatter radars, as well as magnetometer data analyses. When these plasma sheets experienced ExB drifts, they were intercepted by the HAARP UHF radar and seen as slanted stripes in the RTI plots. This striking feature was also observed in our earlier experiments using the Arecibo UHF radar.

  3. THE ARECIBO LEGACY FAST ALFA SURVEY: THE α.40 H I SOURCE CATALOG, ITS CHARACTERISTICS AND THEIR IMPACT ON THE DERIVATION OF THE H I MASS FUNCTION

    International Nuclear Information System (INIS)

    We present a current catalog of 21 cm H I line sources extracted from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey over ∼2800 deg2 of sky: the α.40 catalog. Covering 40% of the final survey area, the α.40 catalog contains 15,855 sources in the regions 07h30m h30m, +04° h h, +14° 2, a factor of 29 improvement over the catalog extracted from the H I Parkes All-Sky Survey. In addition to the source centroid positions, H I line flux densities, recessional velocities, and line widths, the catalog includes the coordinates of the most probable optical counterpart of each H I line detection, and a separate compilation provides a cross-match to identifications given in the photometric and spectroscopic catalogs associated with the Sloan Digital Sky Survey Data Release 7. Fewer than 2% of the extragalactic H I line sources cannot be identified with a feasible optical counterpart; some of those may be rare OH megamasers at 0.16 < z < 0.25. A detailed analysis is presented of the completeness, width-dependent sensitivity function and bias inherent of the α.40 catalog. The impact of survey selection, distance errors, current volume coverage, and local large-scale structure on the derivation of the H I mass function is assessed. While α.40 does not yet provide a completely representative sampling of cosmological volume, derivations of the H I mass function using future data releases from ALFALFA will further improve both statistical and systematic uncertainties.

  4. Capabilities of Earth-based radar facilities for near-Earth asteroid observations

    CERN Document Server

    Naidu, Shantanu P; Margot, Jean-Luc; Busch, Michael W; Taylor, Patrick A

    2016-01-01

    We evaluated the planetary radar capabilities at Arecibo, the Goldstone 70 m DSS-14 and 34-m DSS-13 antennas, the 70-m DSS-43 antenna at Canberra, the Green Bank Telescope, and the Parkes Radio Telescope in terms of their relative sensitivities and the number of known near-Earth asteroids (NEAs) detectable per year in monostatic and bistatic configurations. In the 2015 calendar year, monostatic observations with Arecibo and DSS-14 were capable of detecting 253 and 131 NEAs respectively. Combined, the two observatories were capable of detecting 276 unique NEAs. Of these, Arecibo detected 95 and Goldstone detected 39, or 38% and 30% the numbers that were possible. This indicates that a substantial number of potential targets are not being observed. The bistatic configuration with DSS-14 transmitting and the Green Bank Telescope receiving was capable of detecting about 195 NEAs, or ~50% more than with monostatic observations at DSS-14. Most of the detectable asteroids were targets-of-opportunity that were discov...

  5. Application 0f GIS Partial Discharge UHF On-line Monitoring System%GIS局放特高频在线监测系统的应用

    Institute of Scientific and Technical Information of China (English)

    李杰祎

    2013-01-01

    气体绝缘组合电器GIS在城市电网中得到广泛应用,建立GIS局部放电在线监测系统,对准确掌握设备内部绝缘运行状态和指导检修具有重要意义。本文主要讨论了GIS局部放电产生的原因、GIS局部放电监测的方法、基于特高频检测原理的局放在线监测系统的结构和软件功能以及在工程设计中应该注意的问题。%Developing of GIS Partial Discharge UHF On-line Monitoring System is important for pinpoint holding of insulated run-state in GIS and coach-overhaul,As broad application of gas insulated switchgear in city electric wird.This paper introduces cause of prtial dscharge and measurement of prtial dscharge in GIS ,and instruct of GIS Partial Discharge UHF On-line Monitoring System,and attendant problems in egineering design.

  6. A fully integrated UHF RFID reader SoC for handheld applications in the 0.18 μm CMOS process

    International Nuclear Information System (INIS)

    A low cost fully integrated single-chip UHF radio frequency identification (RFID) reader SoC for short distance handheld applications is presented. The SoC integrates all building blocks-including an RF transceiver, a PLL frequency synthesizer, a digital baseband and an MCU-in a 0.18 μm CMOS process. A high-linearity RX front-end is designed to handle the large self-interferer. A class-E power amplifier with high power efficiency is also integrated to fulfill the function of a UHF passive RFID reader. The measured maximum output power of the transmitter is 20.28 dBm and the measured receiver sensitivity is -60 dBm. The digital baseband including MCU core consumes 3.91 mW with a clock of 10 MHz and the analog part including power amplifier consumes 368.4 mW. The chip has a die area of 5.1 x 3.8 mm2 including pads. (semiconductor integrated circuits)

  7. A fully integrated UHF RFID reader SoC for handheld applications in the 0.18 {mu}m CMOS process

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jingchao; Zhang Chun; Wang Zhihua, E-mail: wangjc@gmail.co [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2010-08-15

    A low cost fully integrated single-chip UHF radio frequency identification (RFID) reader SoC for short distance handheld applications is presented. The SoC integrates all building blocks-including an RF transceiver, a PLL frequency synthesizer, a digital baseband and an MCU-in a 0.18 {mu}m CMOS process. A high-linearity RX front-end is designed to handle the large self-interferer. A class-E power amplifier with high power efficiency is also integrated to fulfill the function of a UHF passive RFID reader. The measured maximum output power of the transmitter is 20.28 dBm and the measured receiver sensitivity is -60 dBm. The digital baseband including MCU core consumes 3.91 mW with a clock of 10 MHz and the analog part including power amplifier consumes 368.4 mW. The chip has a die area of 5.1 x 3.8 mm{sup 2} including pads. (semiconductor integrated circuits)

  8. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears.

    Science.gov (United States)

    Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

    2016-01-01

    In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor. PMID:27472331

  9. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2016-07-01

    Full Text Available In this study a new built-in ultrahigh frequency (UHF antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor.

  10. Simultaneous observations of 46.8-MHz and 430-MHz radar backscatter from HF-induced ionospheric Langmuir turbulence

    International Nuclear Information System (INIS)

    Simultaneous high-resolution spectra of the upshifted enhanced plasma line were obtained with the 46.8-MHz and 430-MHz Arecibo radars in the presence of HF transmissions at two closely spaced frequencies. The spectra obtained with the 46.8-MHz radar showed two narrow features with positive Doppler shifts equal to the two closely spaced frequencies of the HF transmissions; all the spectral power was contained in those two narrow features. The spectra obtained with the 430-MHz radar showed a single narrow feature with a positive Doppler shift equal to the arithmetic mean of the same two closely spaced frequencies; the spectral power in that narrow feature contained about 3% of the total spectral power. The present results broadly confirm the tentative interpretation of earlier observations with a 46.8-MHz radar at Arecibo. The results also show the fundamental difference in the physical processes leading to the enhanced plasma line spectra observed with the two radars

  11. UHF/RFID-kulunvalvontasovellus

    OpenAIRE

    Aatola, Mikko

    2009-01-01

    Etätunnistus on viime vuosina yleistynyt yhä useammilla aloilla. Erityisesti passiivisten eli ilman paristoa toimivien tunnisteiden ja niitä lukevien laitteiden teknologia on kehittynyt merkittävästi. Lukuetäisyydet ovat kasvaneet, toimintavarmuus parantunut ja tunnisteiden hinnat laskeneet. Passiivisesta tekniikasta onkin monessa sovelluskohteessa tullut varteenotettava kilpailija aktiiviselle tekniikalle. Tämän opinnäytetyön tarkoituksena oli kehittää runko yksinkertaiselle, passiivisee...

  12. Observations of A0620-00 by SAS-3

    Science.gov (United States)

    Bradt, H.; Matilsky, T.

    1976-01-01

    The transient X-ray source A0620-00 was observed by the SAS-3 group with the SAS-3 X-ray observatory. At maximum X-ray luminosity limits of 2% were placed on periodic variations from 0.2 ms - 2,000 sec. A precise position was obtained with the rotating modulation collimator. This led directly to radio and optical identification by groups at the NRAO, Arecibo, and McGraw Hill Observatories. The low energy (0.15-0.9 keV) system was pointed at the source, and a spectrum was derived. Hardness ratios are presented, as well as detailed light curves.

  13. Brush-Painting and Photonic Sintering of Copper Oxide and Silver Inks on Wood and Cardboard Substrates to Form Antennas for UHF RFID Tags

    Directory of Open Access Journals (Sweden)

    Erja Sipilä

    2016-01-01

    Full Text Available Additive deposition of inks with metallic inclusions provides compelling means to embed electronics into versatile structures. The need to integrate electronics into environmentally friendly components and structures increases dramatically together with the increasing popularity of the Internet of Things. We demonstrate a novel brush-painting method for depositing copper oxide and silver inks directly on wood and cardboard substrates and discuss the optimization of the photonic sintering process parameters for both materials. The optimized parameters were utilized to manufacture passive ultra high frequency (UHF radio frequency identification (RFID tag antennas. The results from wireless testing show that the RFID tags based on the copper oxide and silver ink antennas on wood substrate are readable from ranges of 8.5 and 11 meters, respectively, and on cardboard substrate from read ranges of 8.5 and 12 meters, respectively. These results are well sufficient for many future wireless applications requiring remote identification with RFID.

  14. Study of the coastal atmospheric boundary layer during ESCOMPTE 2001. Evaluation and improvement of the efficiency of a UHF radar; Etude de la couche limite atmospherique cotiere durant ESCOMPTE 2001. Evaluation et amelioration des performances d'un radar UHF

    Energy Technology Data Exchange (ETDEWEB)

    Puygrenier, V.

    2005-12-15

    Forecasting of pollution events was the main objective of the ESCOMPTE-2001 campaign, which took place in the Marseille/Fos/Berre heterogeneous area (southeastern France) in the early summer 2001. This goal requires good understanding and taking into account, by physico-chemical numerical models, of the physical processes in the Atmospheric Boundary Layer (ABL), in which pollutants are emitted, transported and diffused. In the ESCOMPTE-2001 campaign context, this work was devoted to study the low troposphere during sea breeze events, related to meteorological conditions responsible for poor air quality of coastal areas. It presents notably an oscillation of the sea breeze intensity and competitions of locals and regional sea breeze, which change the advective time of the marine air above the continental surface and thus influence the ABL development and its pollutants concentration. This study is based principally on the network of four UHF wind profilers radars set up on the coastal area of Marseille/Fos/Berre, allowing a continuous three-dimensional description of the sea breeze flow and the ABL. For the needs of this phenomenological work, methodological developments was realized to improve the measurement of ABL turbulent properties with UHF radars (terms of turbulent kinetic energy budget) and the use of wind profilers network for the study of pollutants plumes trajectory-graphy. (author)

  15. THE ARECIBO LEGACY FAST ALFA SURVEY. V. THE H I SOURCE CATALOG OF THE ANTI-VIRGO REGION AT δ = +270

    International Nuclear Information System (INIS)

    We present a second catalog of H I sources detected in the Arecibo Legacy Fast ALFA Survey. We report 488 detections over 135 deg2, within the region of the sky having 22 h 0 0. We present here the detections that have either (a) S/N>6.5, where the reliability of the catalog is better than 95% or (b) 5.0 Hi7.5 Msun are satellites of either the NGC672/IC1727 nearby galaxy pair or their neighboring dwarf irregular galaxy NGC784. The data of this catalog release include a slice through the Pisces-Perseus foreground void, a large nearby underdensity of galaxies. We report no detections within the void, where our catalog is complete for systems with H i masses of 108 Msun. Gas-rich, optically-dark galaxies do not seem to constitute an important void population, and therefore do not suffice for producing a viable solution to the void phenomenon.

  16. 70-cm radar observations of 433 Eros

    Science.gov (United States)

    Campbell, D. B.; Pettengill, G. H.; Shapiro, I. I.

    1976-01-01

    Radar observations of 433 Eros were made at the Arecibo Observatory using a wavelength of 70 cm during the close approach of Eros to earth in mid-January, 1975. A peak radar cross section of plus or minus 15 sq km was observed. The spectral broadening obtained was approximately 30 Hz, which is consistent with a value of 16 km for the maximum radius of the asteroid. The surface of Eros appears to be relatively rough at the scale of a wavelength as compared to the surfaces of the terrestrial planets and the moon. The composition of the surface is not well determined, except that it cannot be a highly conducting metal. A single measurement each of round-trip echo times delay and Doppler shift was made.

  17. SHIELD II: VLA HI Spectral Line Observations

    Science.gov (United States)

    Lee, Eojin; Cannon, John M.; McNichols, Andrew; Teich, Yaron; SHIELD II Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs II" ("SHIELD II") is a multiwavelength, legacy-class observational campaign that is facilitating the study of both internal and global evolutionary processes in low-mass dwarf galaxies discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We present new results from low-resolution D-configuration VLA HI spectral line observations of 6 galaxies in the SHIELD II sample. We explore the morphology and kinematics by comparing images of the HI surface densities and the intensity weighted velocity fields with optical images from SDSS and WIYN. These data allow us to localize the HI gas and to study the bulk neutral gas kinematics.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College.

  18. SHIELD II: WSRT HI Spectral Line Observations

    Science.gov (United States)

    Gordon, Alex Jonah Robert; Cannon, John M.; Adams, Elizabeth A.; SHIELD II Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs II" ("SHIELD II") is a multiwavelength, legacy-class observational campaign that is facilitating the study of both internal and global evolutionary processes in low-mass dwarf galaxies discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We present new results from WSRT HI spectral line observations of 22 galaxies in the SHIELD II sample. We explore the morphology and kinematics by comparing images of the HI surface densities and the intensity weighted velocity fields with optical images from HST, SDSS, and WIYN. In most cases the HI and stellar populations are cospatial; projected rotation velocities range from less than 10 km/s to roughly 30 km/s.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College, and by NASA through grant GO-13750 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

  19. Integrated approach for low-temperature synthesis of high-quality silicon nitride films in PECVD using RF-UHF hybrid plasmas

    Science.gov (United States)

    Sahu, B. B.; Shin, Kyung S.; Han, Jeon G.

    2016-02-01

    This study investigates low-temperature plasma nitriding of hydrogenated silicon (SiN x :H) film in radio frequency (RF) and RF-ultra-high frequency (UHF) hybrid plasmas. To study the optimized conditions for the deposition of SiN x :H film, this work adopts a systematic plasma diagnostic approach in the nitrogen-silane and nitrogen-silane-ammonia plasmas. This work also evaluates the capability of plasma and radical formation by utilizing different plasma sources in the PECVD process. For the plasma diagnostics, we have purposefully used the combination of optical emission spectroscopy (OES), intensified CCD (ICCD) camera, vacuum ultraviolet absorption spectroscopy (VUVAS), and RF compensated Langmuir probe (LP). Data reveal that there is significant enhancement in the atomic nitrogen radicals, plasma densities, and film properties using the hybrid plasmas. Measurements show that addition of a small amount of NH3 can significantly reduce the electron temperature, plasma, and radical density. Also, optical and chemical properties of the deposited films are investigated on the basis of plasma diagnostics. Good quality SiN x :H films, with atomic nitrogen to hydrogen ratio of 4:1, are fabricated. The plasma chemistry of the hybrid plasmas is also discussed for its utility for plasma applications.

  20. Development of a large-area planar surface-wave plasma source with a cavity launcher driven by a 915 MHz UHF wave

    International Nuclear Information System (INIS)

    A large-area planar surface-wave plasma (SWP) source driven by a 915 MHz ultrahigh frequency (UHF) wave was developed. To avoid using large, thick dielectric plates as vacuum windows, we propose a cavity launcher consisting of a cylindrical cavity with several small quartz discs at the bottom. Three types of launchers with quartz discs located at different positions were tested to compare their plasma production efficiencies and spatial distributions of electron density. With the optimum launcher, large-area plasma discharges with a radial uniformity within ±10% were obtained in a radius of about 25–30 cm in Ar gas at 8 Pa for incident power in the range 0.5–2.5 kW. The maximum electron density and temperature were approximately (0.95–1.1) × 1011 cm−3 and 1.9–2.0 eV, respectively, as measured by a Langmuir probe located 24 cm below the bottom of the cavity launcher. Using an Ar/NH3 SWP with the optimum launcher, we demonstrated large-area amino-group surface modification of polyurethane sheets. Experimental results indicated that a uniform amino-group modification was achieved over a radius of approximately 40 cm, which is slightly larger than the radial uniformity of the electron density distribution. (paper)

  1. Design and Simulation of GaussianFSK Transmitter in UHF Band Using Direct Modulation of ΣΔ Modulator Fractional-N Synthesizer

    Directory of Open Access Journals (Sweden)

    Ali Mohammed Noori Hasan

    2008-01-01

    Full Text Available This research involves design and simulation of GaussianFSK transmitter in UHF band using direct modulation of ΣΔ fractional-N synthesizer with the following specifications: Frequency range (869.9– 900.4 MHz, data rate 150kbps, channel spacing (500 kHz, Switching time 1 µs, & phase noise @10 kHz = -85dBc.New circuit techniques have been sought to allow increased integration of radio transmitters and receivers, along with new radio architectures that take advantage of such techniques. Characteristics such as low power operation, small size, and low cost have become the dominant design criteria by which these systems are judged.A direct modulation by ΣΔ fractional-N synthesizer is proposed in this research, because this approach provides the required characteristics such as low power. The Σ∆ modulator placed on digital phase-locked loop to control the fractional value of the frequency division ratio thereby eliminating spurious and allowing good phase noise performance. The modulation type of Gaussian FSK is used to obtain high spectral efficiency of modulated waveform.The applications of this transmitter in low cost wireless data transfer, security systems, RF remote controls and wireless metering.

  2. THE GALEX ARECIBO SDSS SURVEY. VII. THE BIVARIATE NEUTRAL HYDROGEN-STELLAR MASS FUNCTION FOR MASSIVE GALAXIES

    International Nuclear Information System (INIS)

    We present the bivariate neutral atomic hydrogen (H I)-stellar mass function (HISMF) φ(MHI, M*) for massive (log M*/M☉ \\gt 10) galaxies derived from a sample of 480 local (0.025 HI,M*>1010 and find that massive galaxies contribute 41% of the H I density in the local universe. In addition to the binned HISMF, we derive a continuous bivariate fit, which reveals that the Schechter parameters only vary weakly with stellar mass: MHI*, the characteristic H I mass, scales as M*0.39; α, the slope of the HISMF at moderate H I masses, scales as M*0.07; and f, the fraction of galaxies with H I gas fraction greater than 1%, scales as M*-0.24. The variation of f with stellar mass should be a strong constraint for numerical simulations. To understand the physical mechanisms that produce the shape of the HISMF, we redefine the parameters of the Schechter function as explicit functions of stellar mass and star formation rate (SFR) to produce a trivariate fit. This analysis reveals strong trends with SFR. While MHI* varies weakly with stellar mass and SFR (MHI* ∝ M*0.22, MHI* ∝ SFR–0.03), α is a stronger function of both stellar mass and especially SFR (α ∝ M*0.47, α ∝ SFR0.95). The HISMF is a crucial tool that can be used to constrain cosmological galaxy simulations, test observational predictions of the H I content of populations of galaxies, and identify galaxies whose properties deviate from average trends

  3. A passive UHF RFID tag chip with a dual-resolution temperature sensor in a 0.18 μm standard CMOS process

    International Nuclear Information System (INIS)

    This paper presents a passive EPC Gen-2 UHF RFID tag chip with a dual-resolution temperature sensor. The chip tag integrates a temperature sensor, an RF/analog front-end circuit, an NVM memory and a digital baseband in a standard CMOS process. The sensor with a low power sigma—delta (ΣΔ) ADC is designed to operate in low and high resolution modes. It can not only achieve the target accuracy but also reduce the power consumption and the sensing time. A CMOS-only RF rectifier and a single-poly non-volatile memory (NVM) are designed to realize a low cost tag chip. The 192-bit-NVM tag chip with an area of 1 mm2 is implemented in a 0.18-μm standard CMOS process. The sensitivity of the tag is −10.7 dBm/−8.4 dBm when the sensor is disabled/enabled. It achieves a maximum reading/sensing distance of 4 m/3.1 m at 2 W EIRP. The inaccuracy of the sensor is −0.6 °C/0.5 °C (−1.0 °C/1.2 °C) in the operating range from 5 to 15 °C in high resolution mode (−30 to 50 °C in low resolution mode). The resolution of the sensor achieves 0.02 °C (0.18 °C) in high (low) resolution mode. (semiconductor integrated circuits)

  4. Diffuse radio emission in the Coma cluster and Abell 1367: observations at 430 and 1400 MHz

    International Nuclear Information System (INIS)

    Two rich clusters of galaxies, Abell 1656 (the Coma cluster) and Abell 1367, have been mapped at both 430 and 1400 MHz with the 305-m telescope at Arecibo. The contribution to the observed radio emission due to known discrete sources has been calculated by convolving interferometrically determined source lists with observed Arecibo beam patterns, and maps of the diffuse radio emission alone have been constructed. Both clusters contain regions of diffuse radio emission, although the source in Coma is larger and much more luminous than the source in Abell 1367. The linear extent of the diffuse emission and its dependence on frequency have been used to study particle propagation rates and modes of diffusion in the intracluster medium. The possible correlations between the diffuse radio emission and x-ray emission in these clusters have been investigated, and it has been found that the observed x-ray luminosities can be accounted for if the intracluster gas is heated through Coulomb interactions with the relativistic electrons responsible for the diffuse radio emission

  5. UHF截断单极子天线及其匹配网络设计%Design of UHF Truncated Monopole Antenna and Its Matching Network

    Institute of Scientific and Technical Information of China (English)

    张俊睿; 肖绍球; 丁霄; 唐明春; 柏艳英

    2011-01-01

    A broadband monopole antenna working in UHF band is designed. A monopole antenna is cut into two parts. They are connected in series. This step improves the horizontal gain in the upper part of the operating band. A lossless LC ladder is then used to match the antenna impedance from 100 MHz to 400 MHz. The truncating position and circuit element parameters in the matching network are obtained using CST2009 optimization. Reflection coefficients of the truncated antennas both with and without the matching network are measured, showing good agreement with the simulation results. The following conclusions are drawn. The gain in the horizontal direction of the antenna with matching network is more than 0 dBi between 100 MHz and 350 MHz, and stays within -7 ~0 dBi from 350 MHz to 400 MHz. The simulated reflection coefficient 5u of the antenna is below 10 dB within 100 MHz and 400 MHz. The efficiency is over 60% within the operating band.%设计了一个工作在UHF频段的宽带单极子天线.先将单极子天线截为两段并串联起来,以改善天线频率高端的水平方向增益,然后利用无耗LC梯形宽带匹配网络在100~400 MHz对天线进行匹配.用CST2009仿真软件得到优化的天线截断位置和匹配网络元件值等参数.对加载匹配网络前后的截断天线反射系数进行了测试,结果与仿真结果吻合较好.研究表明,加载匹配网络后的天线系统水平增益在100~350 MHz频段大于0 dBi,在350~400 MHz频段介于-7~0 dBi之间.反射系数S11在100~400 MHz频段均小于10 dB,匹配网络效率超过60%.

  6. Phase Coherent Observations and Millisecond Pulsar Searches

    Science.gov (United States)

    Shrauner, Jay Arthur

    1997-07-01

    We have built a new radio astronomical receiving system designed specifically for very high precision timing and polarimetry of fast pulsars. Unlike most detectors currently used to study pulsars, this instrument does not square the received signal at the time of observation. Instead, voltages proportional to the instantaneous electric vectors of incoming signals are digitized, time-tagged, and recorded on high speed magnetic media. During processing, the data streams are convolved with an inverse 'chirp' function that completely removes the phase retardation introduced by interstellar dispersion. The intrinsic time resolution of this system is the inverse of the system bandwidth, typically well under 1 μs. We have tested this and another phase-coherent observing-system in observations using the Arecibo 305 m and Green Bank 140 foot telescopes. With these two sets of observations we have studied giant pulses, performed high precision timing, and obtained high-resolution polarization profiles and accurate dispersion We have verified the existence of pulses with intensities hundreds of measures. times the mean for both the main pulse and interpulse of PSR B1937+21, and have established that the amplitudes of both types of giant pulses have similar power-law distributions. The giant pulses are narrower than the average pulses, systematically delayed by 40-50 μs, and many are nearly 100% circularly polarized. We have also conducted two searches of the Northern hemisphere for pulsars. The first used the original pulsar discovery telescope in Cambridge, England to search the entire Northern hemisphere at 81.5 MHz, with an average sensitivity to slow pulsars of 230 mJy. Although we obtained flux densities and pulse profiles of 20 known pulsars, no new pulsars were discovered. The second search effort covered a total of 384 deg2 of previously unsearched sky at 430 MHz using the Arecibo telescope, with an average sensitivity to slow pulsars of 0.83 mJy. We discovered 7

  7. Simultaneous Multi-angle Observations of Strong Langmuir Turbulence at HAARP

    Science.gov (United States)

    Watanabe, Naomi; Golkowski, Mark; Sheerin, James P.; Watkins, Brenton J.

    2015-10-01

    We report results from a recent series of experiments employing the HF transmitter of the High Frequency Active Auroral Research Program (HAARP) to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. The Modular UHF Ionospheric Radar (MUIR) located at the HAARP facility is used as the primary diagnostic. Short pulse, low duty cycle experiments are used to avoid generation of artificial field-aligned irregularities and isolate ponderomotive plasma turbulence effects. The HF pump frequency is close to the 3rd gyro-harmonic frequency and the HF pointing angle and MUIR look angle are between the HF Spitze angle and Magnetic Zenith angle. Plasma line spectra measured simultaneously in different spots of the interaction region display differences dependent on the aspect angle of the HF pump beam in the boresight direction and the pointing angle of the MUIR diagnostic radar. Outshifted Plasma Lines, cascade, collapse, coexistence, spectra are observed in agreement with existing theory and simulation results of Strong Langmuir Turbulence in ionospheric interaction experiments. It is found that SLT at HAARP is most readily observed at a HF pointing angle of 11° and UHF observation angle of 15°, which is consistent with the magnetic zenith effect as documented in previous works and optimal orientation of the refracted HF electric field vector.

  8. Polar mesosphere summer echoes: a comparison of simultaneous observations at three wavelengths

    Directory of Open Access Journals (Sweden)

    E. Belova

    2008-01-01

    Full Text Available On 5 July 2005, simultaneous observations of Polar Mesosphere Summer Echoes (PMSE were made using the EISCAT VHF (224 MHz and UHF (933 MHz radars located near Tromsø, Norway and the ALWIN VHF radar (53.5 MHz situated on Andøya, 120 km SW of the EISCAT site. During the short interval from 12:20 UT until 12:26 UT strong echoes at about 84 km altitude were detected with all three radars. The radar volume reflectivities were found to be 4×10−13 m−1, 1.5×10−14 m−1 and 1.5×10−18 m−1 for the ALWIN, EISCAT-VHF and UHF radars, respectively. We have calculated the reflectivity ratios for each pair of radars and have compared them to ratios obtained from the turbulence-theory model proposed by Hill (1978a. We have tested different values of the turbulent energy dissipation rate ε and Schmidt number Sc, which are free parameters in the model, to try to fit theoretical reflectivity ratios to the experimental ones. No single combination of the parameters ε and Sc could be found to give a good fit. Spectral widths for the EISCAT radars were estimated from the spectra computed from the autocorrelation functions obtained in the experiment. After correction for beam-width broadening, the spectral widths are about 4 m/s for the EISCAT-VHF and 1.5–2 m/s for the UHF radar. However, according to the turbulence theory, the spectral widths in m/s should be the same for both radars. We also tested an incoherent scatter (IS model developed by Cho et al. (1998, which takes into account the presence of charged aerosols/dust at the summer mesopause. It required very different sizes of particles for the EISCAT-VHF and UHF cases, to be able to fit the experimental spectra with model spectra. This implies that the IS model cannot explain PMSE spectra, at least not for monodisperse distributions of particles.

  9. GIS金属法兰孔特高频信号传播特性研究与外置式发射天线开发%Study on Propagation Characteristics of UHF Signal via Hole of GIS Mental Flange and Development of External Radiating Antenna

    Institute of Scientific and Technical Information of China (English)

    卢启付; 郑书生; 李兴旺; 王亮; 唐志国; 詹花茂

    2013-01-01

    At present, how to inject UHF electromagnetic wave calibration signal into gas-insulated metal-enclosed switchgear (GIS), in which the built-in ultra-high-frequency (UHF) sensor is not installed, is one of the key problems to be faced with during the field sensitivity calibration of online UHF monitoring system for partial discharge in GIS. An external UHF electromagnetic wave transmitting method for GIS, i.e., the calibration signal is injected via hole on metal flange of disc insulator, is proposed. The propagation mode and the structure of electric field of UHF electromagnetic wave passing through the hole is researched by simulation and theoretical analysis;the lower-cut-off frequency of rectangular waveguide antenna is decreased by adding double ridge and the transmitting antenna with double ridge waveguide is developed, and the application effect of the proposed transmitting method and device are validated on GIS. Research results show that the TE10 wave mode is the dominant mode of EM wave passing through the hole, and the lower-cut-off frequency of double ridge waveguide antenna is decreased to 300 MHz, and the double ridge waveguide antenna can transmit UHF calibration signal within the range from 300 MHz to 1.5 GHz into GIS. The proposed external injecting method for UHF calibration signal can provide calibration signal source for field sensitivity calibration of UHF detective instrument for partial discharge in GIS.%  在未安装内置式特高频(ultra-high-frequency,UHF)传感器的情况下,如何向气体绝缘金属封闭开关设备(gas-insulated metal-enclosed switchgear,GIS)内部注入UHF 电磁波标定信号是目前开展GIS局部放电UHF在线监测系统灵敏度现场校验时面临的关键问题之一。提出了 GIS 外置式UHF电磁波发射方法,即通过盆式绝缘子金属法兰小孔注入标定信号。通过仿真和理论分析研究了UHF电磁波经过小孔时的传播模式和电场结构,通过加脊降

  10. ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. I. HI Observations

    CERN Document Server

    Giovanelli, Riccardo; Adams, Elizabeth A K; Cannon, John M; Rhode, Katherine L; Salzer, John J; Skillman, Evan D; Bernstein-Cooper, Elijah Z; McQuinn, Kristen B W

    2013-01-01

    The discovery of a previously unknown 21cm HI line source identified as an ultra-compact high velocity cloud in the ALFALFA survey is reported. The HI detection is barely resolved by the Arecibo 305m telescope ~4' beam and has a narrow HI linewidth (HPFW of 24 km/s). Further HI observations at Arecibo and with the VLA corroborate the ALFALFA HI detection, provide an estimate of the HI radius, ~1' at the 5 x 10^19 cm^-2 isophote, and show the cloud to exhibit rotation with an amplitude of ~9.0 +/- 1.5 km/s. In other papers, Rhode et al. (2013) show the HI source to have a resolved stellar counterpart and ongoing star forming activity, while Skillman et al. (2013) reveal it as having extremely low metallicity: 12 + log(O/H) = 7.16 +/- 0.04. The HI mass to stellar mass ratio of the object is found to be 2.6. We use the Tully-Fisher template relation in its baryonic form (McGaugh 2012) to obtain a distance estimate D = 1.3 (+0.9,-0.5) Mpc. Additional constraints on the distance are also provided by the optical da...

  11. Observing participating observation

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2011-01-01

    Current methodology concerning participating observation in general leaves the act of observation unobserved. Approaching participating observation from systems theory offers fundamental new insights into the topic. Observation is always participation. There is no way to escape becoming a partici......Current methodology concerning participating observation in general leaves the act of observation unobserved. Approaching participating observation from systems theory offers fundamental new insights into the topic. Observation is always participation. There is no way to escape becoming...... as the idea of the naïve observer becomes a void. Not recognizing and observing oneself as observer and co-producer of empirical data simply leaves the process of observation as the major unobserved absorber of contingency in data production based on participating observation....

  12. Observing participating observation

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2010-01-01

    Current methodology concerning participating observation in general leaves the act of observation unobserved. Approaching participating observation from systems theory offers fundamental new insights into the topic. Observation is always participation. There is no way to escape becoming a partici......Current methodology concerning participating observation in general leaves the act of observation unobserved. Approaching participating observation from systems theory offers fundamental new insights into the topic. Observation is always participation. There is no way to escape becoming...... as the idea of the naïve observer becomes a void. Not recognizing and observing oneself as observer and co-producer of empirical data simply leaves the process of observation as the major unobserved absorber of contingency in data production based on participating observation....

  13. A comparison of EISCAT and HF Doppler observations of a ULF wave

    Science.gov (United States)

    Wright, D. M.; Yeoman, T. K.; Davies, J. A.

    1998-10-01

    Since the middle of 1995, an HF Doppler sounder has been running almost continuously in northern Norway, with the receiver at Ramfjordmoen and the transmitter at Seljelvnes. Concurrent operation of the EISCAT UHF radar in common programme (CP-1) mode has made it possible to study the ionospheric signature of a magnetospheric ULF wave. These are the first results of such wave signatures observed simultaneously in both instruments. It has been demonstrated that the observed Doppler signature was mainly due to the vertical bulk motion of the ionosphere caused by the electric field perturbation of the ULF wave and the first direct observational confirmation of a numerical simulation has been achieved. The wave, which was Alfvénic in nature, was detected by the instruments 8° equatorward of the broad resonance region. The implications for the deduced wave modes in the ionosphere and the mechanism producing the HF Doppler variations are discussed.

  14. Upgrade to the Broadband Observation network for Lightning and Thunderstorms

    Science.gov (United States)

    Akiyama, Y.; Wu, T.; Stock, M.; Nakamura, Y.; Kikuchi, H.; Yoshida, S.; Ushio, T.; Kawasaki, Z.

    2015-12-01

    Observation sensors for lightning discharges sense electromagnetic waves, mainly in the ELF to UHF range, and especially in the LF and VHF bands. VHF band sensor sensors can observe lightning discharge process in detail but its observation coverage is limited. On the other hand, LF band sensor can observe lightning at much great distances. Therefore, LF sensors are well adapted to observe lightning throughout a thunderstorm's life cycle. Our research group has been designing and developing the Broadband Observation network for Lightning and Thunderstorm (BOLT), which locates radiation sources associated with lightning discharge in three spatial dimensions. BOLT consists of 11 LF band sensors which detect lightning pulses wide frequency range from 5 kHz to 500 kHz. We have been operating BOLT in Kansai area of Japan, locating both cloud-to-ground and intracloud discharges. Currently, the BOLT system observes about 100 to 1000 lightning pulses per flash, but we are striving to improve both the detection efficiency and the location accuracy. Preliminary investigation show that the number of sources located, increases dramatically when only the highest portion of the BLOT frequency band is used far location. So, our research group has proposed improving a new "DDT" antenna sensor design to improve the high frequency sensitivity of the antenna. The DDT antenna consists of a modified charge amplifier circuit. In this research, we present a comparison of the DDT antenna and show the advantages of the DDT antenna.

  15. Radar Observations and the Shape of Near-Earth Asteroid 2008 EV5

    CERN Document Server

    Busch, Michael W; Benner, Lance A M; Brozovic, Marina; Giorgini, Jon D; Jao, Joseph S; Scheeres, Daniel J; Magri, Christopher; Nolan, Michael C; Howell, Ellen S; Taylor, Patrick A; Margot, Jean-Luc; Brisken, Walter

    2011-01-01

    We observed the near-Earth asteroid 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 /pm 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid's equator that is broken by a concavity 150 m in diameter. Otherwise the asteroid's surface is notably smooth on decameter scales. EV5's radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure.

  16. Lidar observation of aerosol stratification in the lower troposphere over Pune during pre-monsoon season of 2006

    Indian Academy of Sciences (India)

    P Ernest Raj; S K Saha; S M Sonbawne; S M Deshpande; P C S Devara; Y Jaya Rao; K K Dani; G Pandithurai

    2008-07-01

    Lidar observations of aerosol vertical distributions in the lower troposphere along with observations of horizontal and vertical winds from collocated UHF radar (Wind Profiler) over a tropical Indian station, Pune during the pre-monsoon season (March–May) of 2006 as part of an ISRO-GBP national campaign (ICARB) have been examined. Lidar vertical profiles showed high aerosol concentrations in the surface layers and a subsequent gradual decrease with height. Results showed the presence of an elevated stratified aerosol layer around 2000–3500m height which persisted throughout the months of March and April. Observed strong vertical gradients in both horizontal and vertical winds in the lower troposphere seem to be a possible cause for the formation of elevated aerosol layers. Further, high daytime temperatures accompanied by dry conditions at the surface help to enhance the aerosol loading in the lower layers over this location.

  17. On the role of parametric instability of internal gravity waves in atmospheric radar observations

    Science.gov (United States)

    Klostermeyer, J.

    1990-10-01

    Parametric instability of internal gravity waves is discussed on the basis of observational results obtained from an FM-CW tropospheric UHF radar and pulsed mesospheric VHF Doppler radars. At small primary wave amplitudes, the instability modes can be comparable to that of the primary wave, leading to a broadening or continuous wave number spectrum. Long-period primary waves propagate almost vertically and form extended layers moving with the phase velocity of the primary wave. These modes satisfy Taylor's frozen turbulence field hypothesis, so that the Doppler shift of scattered radar signals yields the space and time dependent fluid velocity of the primary wave. At sufficiently large amplitudes, there is a fast-growing instability mode with frequencies near the Vaisala-Brunt frequency, which is reminiscent of the Kelvin-Helmholtz instability of horizontally stratified time independent shear flows.

  18. The NANOGrav Nine-year Data Set: Observations, Arrival Time Measurements, and Analysis of 37 Millisecond Pulsars

    CERN Document Server

    Arzoumanian, Z; Burke-Spolaor, S; Chamberlin, S; Chatterjee, S; Christy, B; Cordes, J M; Cornish, N; Crowter, K; Demorest, P B; Dolch, T; Ellis, J A; Ferdman, R D; Fonseca, E; Garver-Daniels, N; Gonzalez, M E; Jenet, F A; Jones, G; Jones, M; Kaspi, V M; Koop, M; Lazio, T J W; Lam, M T; Levin, L; Lommen, A N; Lorimer, D R; Luo, J; Lynch, R S; Madison, D; McLaughlin, M A; McWilliams, S T; Nice, D J; Palliyaguru, N; Pennucci, T T; Ransom, S M; Siemens, X; Stairs, I H; Stinebring, D R; Stovall, K; Swiggum, J K; Vallisneri, M; van Haasteren, R; Wang, Y; Zhu, W

    2015-01-01

    We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In conjunction with the timing model fit, we have performed a Bayesian analysis of a parameterized timing noise model for each source, and detect evidence for time-correlated "red" signals in 10 of the pulsars. Subsequent papers in this series will present further analysis of this data set aimed at detecting o...

  19. Microwave Observatory of Subcanopy and Subsurface (MOSS): A Mission for Global Observations of Deep Soil Moisture

    Science.gov (United States)

    Moghaddam, M.; Rodriguez, E.; Rahmat-Samii, Y.; Moller, D.; Hoffman, J. P.; Pierce, L.; Huang, J.

    2005-12-01

    The microwave observatory of subcanopy and subsurface (MOSS) Instrument Incubator project has developed a mission concept and advanced the technologies for a SAR mission that provides global observations of soil moisture under substantial vegetation canopies and at useful depths. This VHF/UHF polarimetric SAR is designed to provide 7-10 day repeat observations of soil moisture under substantial vegetation canopies and at depths reaching 1-5 meters, at 1 Km resolution. Due to the rapid repeat cycle, the required swath width is 300-400 Km, which must be realized by a 30m long antenna. Conventional array implementations would result in a mass of over 4000 Kg, whereas with the technology proposed and demonstrated in this project, the total antenna mass becomes about 400 kg. This antenna concept is implemented by a dual-stack patch array feed illuminating a 30m mesh reflector to synthesize the required long rectangular apertures and achieve the wide swath. This feed system was designed, and a prototype built and demonstrated. Initially, a scaled version was built and tested, which was also integrated with a scaled reflector antenna for demonstration of the overall antenna system. The full-size low frequency feed was also built and its performance successfully demonstrated. The technology was therefore taken to TRL 5-6 from 3. Other components of this project were the demonstration of the science data and products, which was achieved through a tower-based VHF/UHF radar. Experimental data were generated for deep penetration in the Arizona desert, as well as for forest penetration in a dense forest in Oregon. The soil moisture products were demonstrated and in so doing, a new integrated inversion-processing algorithm was developed. This paper will present the overall mission concept, technologies developed, science data products, and the recommended next steps.

  20. Arecibo, Puerto Rico Coastal Digital Elevation Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated...

  1. First estimates of volume distribution of HF-pump enhanced emissions at 6300 and 5577 Å: a comparison between observations and theory

    Directory of Open Access Journals (Sweden)

    B. Gustavsson

    2008-12-01

    Full Text Available We present bi-static observations of radio-wave induced optical emissions at 6300 and 5577 Å from a night-time radio-induced optical emission ionospheric pumping experiment at the HIPAS (Fairbanks facility in Alaska. The optical observations were made at HIPAS and from HAARP located 285 km south-east. From these observations the altitude distribution of the emissions is estimated with tomography-like methods. These estimates are compared with theoretical models. Other diagnostics used to support the theoretical calculations include the new Poker Flat AMISR UHF radar near HIPAS. We find that the altitude distribution of the emissions agree with electron transport modeling with a source of accelerated electrons located 20 km below the upper-hybrid altitude.

  2. 基于μC/OS-Ⅱ的超高频双协议RFID读写器设计%Design of dual-protocol UHF RFID reader based on μC/OS-Ⅱ

    Institute of Scientific and Technical Information of China (English)

    商昌彬; 马庆彪; 张玉璘

    2012-01-01

    In the ISO 18000-6 standard, 6B is mainly used in traffic area and 6C is mainly used in logistics, production management and supply chain management, the two are now commonly used standard protocol. Thus, ihe paper designs a UHF RFID reader that both support ISOI8000-6 B and 6C dual-protocol. The design is baaed on the special chip AS3992 modules and LM3S8962 primarily control module, carrying jxC/OS- II system, that can read or write from tags for a Long distance through a series of operations such as the UART initialization, AS3992 drive, anti-collision algorithm, CRC checking and registers of modifying etc. This system has the characteristics of simple development, low power, small volume and low cost.%在超高频段,ISO18000-6标准中的6B多用于交通领域,而6C主要用于物流、生产管理和供应链管理领域,二者都是目前常用的标准协议.鉴于此,提出一种同时支持ISO18000-6B和6C双协议超高频RFID读写器的设计.该设计采用基于专用芯片AS3992的射频前端模块和以LM3S8962为主的控制模块,搭载μC/OS-Ⅱ系统,通过程序进行串口初始化、AS3992驱动、防碰撞算法、CRC校验和寄存器的读写操作等实现对电子标签的远距离操作.本系统具有开发简单、功耗低、体积小、成本低的特点.

  3. Determination of meteoroid physical properties from tristatic radar observations

    Directory of Open Access Journals (Sweden)

    J. Kero

    2008-08-01

    Full Text Available In this work we give a review of the meteor head echo observations carried out with the tristatic 930 MHz EISCAT UHF radar system during four 24 h runs between 2002 and 2005 and compare these with earlier observations. A total number of 410 tristatic meteors were observed. We describe a method to determine the position of a compact radar target in the common volume monitored by the three receivers and demonstrate its applicability for meteor studies. The inferred positions of the meteor targets have been utilized to estimate their velocities, decelerations and directions of arrival as well as their radar cross sections with unprecedented accuracy. The velocity distribution of the meteoroids is bimodal with peaks at 35–40 km/s and 55–60 km/s, and ranges from 19–70 km/s. The estimated masses are between 10−9–10−5.5 kg. There are very few detections below 30 km/s. The observations are clearly biased to high-velocity meteoroids, but not so biased against slow meteoroids as has been presumed from previous tristatic measurements. Finally, we discuss how the radial deceleration observed with a monostatic radar depends on the meteoroid velocity and the angle between the trajectory and the beam. The finite beamwidth leads to underestimated meteoroid masses if radial velocity and deceleration of meteoroids approaching the radar are used as estimates of the true quantities in a momentum equation of motion.

  4. 2MTF III. HI 21cm observations of 1194 spiral galaxies with the Green Bank Telescope

    CERN Document Server

    Masters, Karen L; Hong, Tao; Jarrett, T H; Koribalski, Baerbel S; Macri, Lucas; Springob, Christopher M; Staveley-Smith, Lister

    2014-01-01

    We present HI 21cm observations of 1194 galaxies out to a redshift of 10,000 km/s selected as inclined spirals (i>60deg) from the 2MASS Redshift Survey. These observations were carried out at the National Radio Astronomy Observatory Robert C. Byrd Green Bank Telescope (GBT). This observing program is part of the 2MASS Tully-Fisher (2MTF) survey. This project will combine HI widths from these GBT observations with those from further dedicated observing at the Parkes Telescope, from the ALFALFA survey at Arecibo, and S/N>10 and spectral resolution, v_res < 10km/s published widths from a variety of telescopes. We will use these HI widths along with 2MASS photometry to estimate Tully-Fisher distances to nearby spirals and investigate the peculiar velocity field of the local Universe. In this paper we report on detections of neutral hydrogen in emission in 727 galaxies, and measure good signal-to-noise and symmetric HI global profiles suitable for use in the Tully-Fisher relation in 484.

  5. Passive UHF RFID Tag for Multispectral Assessment.

    Science.gov (United States)

    Escobedo, Pablo; Carvajal, Miguel A; Capitán-Vallvey, Luis F; Fernández-Salmerón, José; Martínez-Olmos, Antonio; Palma, Alberto J

    2016-01-01

    This work presents the design, fabrication, and characterization of a passive printed radiofrequency identification tag in the ultra-high-frequency band with multiple optical sensing capabilities. This tag includes five photodiodes to cover a wide spectral range from near-infrared to visible and ultraviolet spectral regions. The tag antenna and circuit connections have been screen-printed on a flexible polymeric substrate. An ultra-low-power microcontroller-based switch has been included to measure the five magnitudes issuing from the optical sensors, providing a spectral fingerprint of the incident electromagnetic radiation from ultraviolet to infrared, without requiring energy from a battery. The normalization procedure has been designed applying illuminants, and the entire system was tested by measuring cards from a colour chart and sensing fruit ripening. PMID:27428973

  6. Passive UHF RFID Tag for Multispectral Assessment

    Directory of Open Access Journals (Sweden)

    Pablo Escobedo

    2016-07-01

    Full Text Available This work presents the design, fabrication, and characterization of a passive printed radiofrequency identification tag in the ultra-high-frequency band with multiple optical sensing capabilities. This tag includes five photodiodes to cover a wide spectral range from near-infrared to visible and ultraviolet spectral regions. The tag antenna and circuit connections have been screen-printed on a flexible polymeric substrate. An ultra-low-power microcontroller-based switch has been included to measure the five magnitudes issuing from the optical sensors, providing a spectral fingerprint of the incident electromagnetic radiation from ultraviolet to infrared, without requiring energy from a battery. The normalization procedure has been designed applying illuminants, and the entire system was tested by measuring cards from a colour chart and sensing fruit ripening.

  7. LF RFID -tekniikan korvaaminen UHF RFID -tekniikalla

    OpenAIRE

    Paananen, Jarkko

    2013-01-01

    Työ toteutettiin automatisoituun pesulaan, jossa vaatteet tunnistetaan matalataajuisella etätunnistuksella. Pesulassa oli yritetty korvata matalataajuinen etätunnistusjärjestelmää korkeataajuisella etätunnistusjärjestelmällä. Työn tavoitteena oli ratkaista ongelmat, joita vaihdoksessa ilmenee. Ongelmia olivat vanhan ja uuden järjestelmän rin-nakkain toimiminen, etätunnistettavan tunnistuksen kohdistaminen, etätunnistettavien yhtäaikainen tunnistus ja ettei samaa etätunnistettavaa tunnistettai...

  8. Modeling UHF Radio Propagation in Buildings.

    Science.gov (United States)

    Honcharenko, Walter

    The potential implementation of wireless Radio Local Area Networks and Personal Communication Services inside buildings requires a thorough understanding of signal propagation within buildings. This work describes a study leading to a theoretical understanding of wave propagation phenomenon inside buildings. Covered first is propagation in the clear space between the floor and ceiling, which is modeled using Kirchoff -Huygens diffraction theory. This along with ray tracing techniques are used to develop a model to predict signal coverage inside buildings. Simulations were conducted on a hotel building, two office buildings, and a university building to which measurements of CW signals were compared, with good agreement. Propagation to other floors was studied to determine the signal strength as a function of the number of floors separating transmitter and receiver. Diffraction paths and through the floor paths which carry significant power to the receivers were examined. Comparisons were made to measurements in a hotel building and an office building, in which agreements were excellent. As originally developed for Cellular Mobile Radio (CMR) systems, the sector average is obtained from the spatial average of the received signal as the mobile traverses a path of 20 or so wavelengths. This approach has also been applied indoors with the assumption that a unique average could be obtained by moving either end of the radio link. However, unlike in the CMR environment, inside buildings both ends of the radio link are in a rich multipath environment. It is shown both theoretically and experimentally that moving both ends of the link is required to achieve a unique average. Accurate modeling of the short pulse response of a signal within a building will provide insight for determining the hardware necessary for high speed data transmission and recovery, and a model for determining the impulse response is developed in detail. Lastly, the propagation characteristics of concrete walls are examined. Theoretical and experimental studies were conducted to determine their transmission and reflections coefficients with respect to incidence angle. Furthermore, Floquet' s theory of periodic structures was used to compute the space harmonic modes introduced by the periodicity of concrete blocks.

  9. Broadband circularly polarized antennas for UHF SATCOM

    OpenAIRE

    Tekin, İbrahim; Tekin, Ibrahim; Manzhura, Oksana; Niver, Edip

    2011-01-01

    Novel circularly polarized (CP) antenna configurations derived from Moxon type antenna (bent dipole element over a ground plane) for broadband VHF SATCOM applications. A sequence of topologies starting from a single vertical element to two vertical elements of the Moxon arms, then widened strip arm elements were studied. Further, arms were widened to bow tie structures with bents at 900.for achieving broadband operation. Bow tie elements were further split and optimized at a certain angle to...

  10. Mars Surveyor Program and UHF Telemetry Communications

    OpenAIRE

    Toro-Allen, Scott; Anderson, Christopher

    1996-01-01

    Beginning in November 1996 with the launch of the Mars Global Surveyor (MGS), NASA will embark on a decade-long exploration of the planet Mars using a series of robotic spacecrafts. Launched approximately every 26 months, these probes will carry Orbiters, Landers, and Rovers with the intent of mapping the planet while characterizing its climate, along with a search for water and possible life, past or present. Severe budgetary constraints on these missions and their highly focused scientific ...

  11. The Scintillation Prediction Observations Research Task (SPORT) Mission

    Science.gov (United States)

    Spann, James; Swenson, Charles; Durão, Otavio; Loures, Luis; Heelis, Rod; Bishop, Rebecca; Le, Guan; Abdu, Mangalathayil; Krause, Linda; Nardin, Clezio; Fonseca, Eloi

    2016-04-01

    Structure in the charged particle number density in the equatorial ionosphere can have a profound impact on the fidelity of HF, VHF and UHF radio signals that are used for ground-to-ground and space-to-ground communication and navigation. The degree to which such systems can be compromised depends in large part on the spatial distribution of the structured regions in the ionosphere and the background plasma density in which they are embedded. In order to address these challenges it is necessary to accurately distinguish the background ionospheric conditions that favor the generation of irregularities from those that do not. Additionally we must relate the evolution of those conditions to the subsequent evolution of the irregular plasma regions themselves. The background ionospheric conditions are conveniently described by latitudinal profiles of the plasma density at nearly constant altitude, which describe the effects of ExB drifts and neutral winds, while the appearance and growth of plasma structure requires committed observations from the ground from at least one fixed longitude. This talk will present an international collaborative CubeSat mission called SPORT that stands for the Scintillation Prediction Observations Research Task. This mission will advance our understanding of the nature and evolution of ionospheric structures around sunset to improve predictions of disturbances that affect radio propagation and telecommunication signals. The science goals will be accomplished by a unique combination of satellite observations from a nearly circular middle inclination orbit and the extensive operation of ground based observations from South America near the magnetic equator. This approach promises Explorer class science at a CubeSat price.

  12. Calibration of a numerical ionospheric model with EISCAT observations

    Directory of Open Access Journals (Sweden)

    P.-L. Blelly

    Full Text Available A set of EISCAT UHF and VHF observations is used for calibrating a coupled fluid-kinetic model of the ionosphere. The data gathered in the period 1200- 2400 UT on 24 March 1995 had various intervals of interest for such a calibration. The magnetospheric activity was very low during the afternoon, allowing for a proper examination of a case of quiet ionospheric conditions. The radars entered the auroral oval just after 1900 UT: a series of dynamic events probably associated with rapidly moving auroral arcs was observed until after 2200 UT. No attempts were made to model the dynamical behaviour during the 1900–2200 UT period. In contrast, the period 2200–2400 UT was characterised by quite steady precipitation: this latter period was then chosen for calibrating the model during precipitation events. The adjustment of the model on the four primary parameters observed by the radars (namely the electron concentration and temperature and the ion temperature and velocity needed external inputs (solar fluxes and magnetic activity index and the adjustments of a neutral atmospheric model in order to reach a good agreement. It is shown that for the quiet ionosphere, only slight adjustments of the neutral atmosphere models are needed. In contrast, adjusting the observations during the precipitation event requires strong departures from the model, both for the atomic oxygen and hydrogen. However, it is argued that this could well be the result of inadequately representing the vibrational states of N2 during precipitation events, and that these factors have to be considered only as ad hoc corrections.

  13. The Scintillation Prediction Observations Research Task (SPORT) Mission

    Science.gov (United States)

    Spann, James; Le, Guan; Swenson, Charles; Denardini, Clezio Marcos; Bishop, Rebecca L.; Abdu, Mangalathayil A.; Cupertino Durao, Otavio S.; Heelis, Roderick; Loures, Luis; Krause, Linda; Fonseca, Eloi

    2016-07-01

    Structure in the charged particle number density in the equatorial ionosphere can have a profound impact on the fidelity of HF, VHF and UHF radio signals that are used for ground-to-ground and space-to-ground communication and navigation. The degree to which such systems can be compromised depends in large part on the spatial distribution of the structured regions in the ionosphere and the background plasma density in which they are embedded. In order to address these challenges it is necessary to accurately distinguish the background ionospheric conditions that favor the generation of irregularities from those that do not. Additionally we must relate the evolution of those conditions to the subsequent evolution of the irregular plasma regions themselves. The background ionospheric conditions are conveniently described by latitudinal profiles of the plasma density at nearly constant altitude, which describe the effects of ExB drifts and neutral winds, while the appearance and growth of plasma structure requires committed observations from the ground from at least one fixed longitude. This talk will present an international collaborative CubeSat mission called SPORT that stands for the Scintillation Prediction Observations Research Task. This mission will advance our understanding of the nature and evolution of ionospheric structures around sunset to improve predictions of disturbances that affect radio propagation and telecommunication signals. The science goals will be accomplished by a unique combination of satellite observations from a nearly circular middle inclination orbit and the extensive operation of ground based observations from South America near the magnetic equator. This approach promises Explorer class science at a CubeSat price.

  14. Simultaneous Multi-angle Radar Observations of Langmuir Turbulence Excited by RF Ionospheric Interactions at HAARP

    Science.gov (United States)

    Sheerin, J. P.; Rayyan, N.; Watanabe, N.; Watkins, B. J.; Bristow, W. A.; Bernhardt, P. A.

    2013-10-01

    The high power HAARP HF transmitter is employed to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. Diagnostics included the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, and HF receivers to record stimulated electromagnetic emissions (SEE). Dependence of diagnostic signals on HAARP HF parameters, including pulselength, duty-cycle, aspect angle, and frequency were recorded. Short pulse, low duty cycle experiments demonstrate control of artificial field-aligned irregularities (AFAI) and isolation of ponderomotive effects. Among the effects observed and studied are: SLT spectra including cascade, collapse, and co-existence spectra and an outshifted plasma line under certain ionospheric conditions. High time resolution studies of the temporal evolution of the plasma line reveal the appearance of an overshoot effect on ponderomotive timescales. Bursty turbulence is observed in the collapse and cascade lines. For the first time, simultaneous multi-angle radar measurements of plasma line spectra are recorded demonstrating marked dependence on aspect angle with the strongest interaction region observed displaced southward of the HF zenith pointing angle. Numerous measurements of the outshifted plasma line are observed. Experimental results are compared to previous high latitude experiments and predictions from recent modeling efforts.

  15. Tristatic observations of meteors using the 930 MHz European Incoherent Scatter radar system

    Science.gov (United States)

    Janches, Diego; Pellinen-Wannberg, Asta; Wannberg, Gudmund; Westman, Assar; HäGgströM, Ingemar; Meisel, David D.

    2002-11-01

    We report results from the first tristatic measurements of radar meteors obtained during 17 November 1997 and 1998, using the UHF (930 MHz) European Incoherent Scatter (EISCAT) radar system. The observing technique utilized for these observations was first reported by [1998a]. This system consists of three 32-m parabolic antennae located in northern Scandinavia. Since EISCAT observes mostly meteor head echoes, a general characteristic of high-power/large-aperture radars, direct Doppler velocity (±1 km/s) determinations are possible. In addition, using the technique reported here, absolute geocentric meteor velocity and good radiant information (±5°) are deduced for those meteors that are detected simultaneously by all three receivers. An overview of the methodology and a summary of the results obtained so far are reported in this work. We compare the results obtained using this method with those reported by previous large-aperture meteor radar work at lower frequencies and find general agreement. EISCAT detects mainly sporadic particles extending the fast daily sporadic micrometeor storms first suggested by [2000b] and [2001] to submillimeter particles. To the best of our knowledge, these observations represent the first of their kind and prove EISCAT to be a crucial instrument for the study of extraterrestrial particles entering the Earth's atmosphere, in particular at very high geocentric latitudes and high geocentric speeds.

  16. The repeating Fast Radio Burst FRB 121102: Multi-wavelength observations and additional bursts

    CERN Document Server

    Scholz, P; Hessels, J W T; Chatterjee, S; Cordes, J M; Kaspi, V M; Wharton, R S; Bassa, C G; Bogdanov, S; Camilo, F; Crawford, F; Deneva, J; van Leeuwen, J; Lynch, R; Madsen, E C; McLaughlin, M A; Mickaliger, M; Parent, E; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; Tendulkar, S P

    2016-01-01

    We report on radio and X-ray observations of the only known repeating Fast Radio Burst (FRB) source, FRB 121102. We have detected six additional radio bursts from this source: five with the Green Bank Telescope at 2 GHz, and one at 1.4 GHz at the Arecibo Observatory for a total of 17 bursts from this source. All have dispersion measures consistent with a single value ($\\sim559$ pc cm$^{-3}$) that is three times the predicted maximum Galactic value. The 2-GHz bursts have highly variable spectra like those at 1.4 GHz, indicating that the frequency structure seen across the individual 1.4 and 2-GHz bandpasses is part of a wideband process. X-ray observations of the FRB 121102 field with the Swift and Chandra observatories show at least one possible counterpart; however, the probability of chance superposition is high. A radio imaging observation of the field with the Jansky Very Large Array at 1.6 GHz yields a 5$\\sigma$ upper limit of 0.3 mJy on any point-source continuum emission. This upper limit, combined wit...

  17. Satellite observations

    Science.gov (United States)

    1984-05-01

    In 1982 and 1983, six scientific satellites were operated successfully. Two of them, JIKIKEN and ISS-b, performed observations of the Earth's plasma environment. HINOTORI, the solar maximum satellite, observed a number of solar flares. HAKUCHO and newly launched TENMA conducted various observations of cosmic X-ray sources. HIMAWARI-2 is a meteorological satellite but its payload includes a solar particle monitor. EXOS-C was successfully launched in February, 1983, and participants in the MAP (Middle Atmosphere Program). Following these missions, the PLANET-A project comprising two missions, MS-T5 and PLANET-A, is under preparation for the participation in the international cooperative exploration of Comet P/Halley. The third X-ray astronomy satellite ASTRO-C is currently scheduled for 1987 launch.

  18. Observational $\\Delta\

    CERN Document Server

    Hernández, Antonio García; Monteiro, Mário J P F G; Suárez, Juan Carlos; Reese, Daniel R; Pascual-Granado, Javier; Garrido, Rafael

    2015-01-01

    Delta Scuti ($\\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\\delta$ Sct stars.

  19. Scintillation Arcs in Low-frequency Observations of the Timing-array Millisecond Pulsar PSR J0437-4715

    Science.gov (United States)

    Bhat, N. D. R.; Ord, S. M.; Tremblay, S. E.; McSweeney, S. J.; Tingay, S. J.

    2016-02-01

    Low-frequency observations of pulsars provide a powerful means for probing the microstructure in the turbulent interstellar medium (ISM). Here we report on high-resolution dynamic spectral analysis of our observations of the timing-array millisecond pulsar PSR J0437-4715 with the Murchison Widefield Array (MWA), enabled by our recently commissioned tied-array beam processing pipeline for voltage data recorded from the high time resolution mode of the MWA. A secondary spectral analysis reveals faint parabolic arcs akin to those seen in high-frequency observations of pulsars with the Green Bank and Arecibo telescopes. Data from Parkes observations at a higher frequency of 732 MHz reveal a similar parabolic feature with a curvature that scales approximately as the square of the observing wavelength (λ2) to the MWA's frequency of 192 MHz. Our analysis suggests that scattering toward PSR J0437-4715 predominantly arises from a compact region about 115 pc from the Earth, which matches well with the expected location of the edge of the Local Bubble that envelopes the local Solar neighborhood. As well as demonstrating new and improved pulsar science capabilities of the MWA, our analysis underscores the potential of low-frequency pulsar observations for gaining valuable insights into the local ISM and for characterizing the ISM toward timing-array pulsars.

  20. Macroscopic observables

    International Nuclear Information System (INIS)

    We study macroscopic observables defined as the total value of a physical quantity over a collection of quantum systems. We show that previous results obtained for an infinite ensemble of identically prepared systems lead to incorrect conclusions for finite ensembles. In particular, exact measurement of a macroscopic observable significantly disturbs the state of any finite ensemble. However, we show how this disturbance can be made arbitrarily small when the measurements are of finite accuracy. We demonstrate a general trade-off between state disturbance and measurement coarseness as a function of the size of the ensemble. Using this trade-off, we show that the histories generated by any sequence of finite accuracy macroscopic measurements always generate a consistent family in the absence of large-scale entanglement for sufficiently large ensembles. Hence, macroscopic observables behave 'classically' provided that their accuracy is coarser than the quantum correlation length scale of the system. The role of these observable is also discussed in the context of NMR quantum information processing and bulk ensemble quantum state tomography

  1. Babylonian observations

    Science.gov (United States)

    Brown, D.

    Very few cuneiform records survive from Mesopotamia of datable astronomical observations made prior to the mid-eighth century BC. Those that do record occasional eclipses, and in one isolated case the dates of the heliacal rising and setting of Venus over a few years sometime in the first half of the second millennium BC. After the mid-eighth century BC the situation changes dramatically. Incomplete records of daily observations of astronomical and meteorological events are preserved from c. 747 BC until the Christian Period. These records are without accompanying ominous interpretation, although it is highly probable that they were compiled by diviners for astrological purposes. They include numerous observations of use to historical astronomers, such as the times of eclipses and occultations, and the dates of comet appearances and meteor showers. The question arises as to why such records do not survive from earlier times; celestial divination was employed as far back as the third millenium BC. It is surely not without importance that the earliest known accurate astronomical predictions accompany the later records, and that the mid-eighth century BC ushered in a period of centralised Assyrian control of Mesopotamia and the concomitant employment by the Assyrian ruler of large numbers of professional celestial diviners. The programme of daily observations evidently began when a high premium was first set on the accurate astronomical prediction of ominous events. It is in this light that we must approach this valuable source material for historical astronomy.

  2. Flare Observations

    Directory of Open Access Journals (Sweden)

    Benz Arnold O.

    2008-02-01

    Full Text Available Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays at 100 MeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, and SOHO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections (CMEs, electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting reconnection of magnetic field lines as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth’s lower ionosphere. While flare scenarios have slowly converged over the past decades, every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

  3. A comparison of EISCAT and HF Doppler observations of a ULF wave

    Directory of Open Access Journals (Sweden)

    D. M. Wright

    Full Text Available Since the middle of 1995, an HF Doppler sounder has been running almost continuously in northern Norway, with the receiver at Ramfjordmoen and the transmitter at Seljelvnes. Concurrent operation of the EISCAT UHF radar in common programme (CP-1 mode has made it possible to study the ionospheric signature of a magnetospheric ULF wave. These are the first results of such wave signatures observed simultaneously in both instruments. It has been demonstrated that the observed Doppler signature was mainly due to the vertical bulk motion of the ionosphere caused by the electric field perturbation of the ULF wave and the first direct observational confirmation of a numerical simulation has been achieved. The wave, which was Alfvénic in nature, was detected by the instruments 8° equatorward of the broad resonance region. The implications for the deduced wave modes in the ionosphere and the mechanism producing the HF Doppler variations are discussed.

    Key words. Magnetosphere-ionosphere interactions · MHD waves and instabilities · Radio science · Ionospheric physics

  4. Observing environments

    DEFF Research Database (Denmark)

    Alrøe, Hugo Fjelsted; Noe, Egon

    2012-01-01

    Context: Society is faced with “wicked” problems of environmental sustainability, which are inherently multiperspectival, and there is a need for explicitly constructivist and perspectivist theories to address them. Problem: However, different constructivist theories construe the environment in...... different ways. The aim of this paper is to clarify the conceptions of environment in constructivist approaches, and thereby to assist the sciences of complex systems and complex environmental problems. Method: We describe the terms used for “the environment” in von Uexküll, Maturana & Varela, and Luhmann......, and analyse how their conceptions of environment are connected to differences of perspective and observation. Results: We show the need to distinguish between inside and outside perspectives on the environment, and identify two very different and complementary logics of observation, the logic of...

  5. Observation of suprathermal electron fluxes during ionospheric modification experiments

    International Nuclear Information System (INIS)

    The temporal behavior of backscatter by ionospheric Langmuir waves was observed with the 430-MHz radar at Arecibo while a powerful HF wave was cycled 2 s on, 3 s off. The time resolution was 0.1 s. Late at night, in the absence of photoelectrons, using an HF equivalent radiated power of 80 MW at 3.175 MHz, the initial enhancement of about 6% above system noise of the backscattered power with Doppler shifts between -3.75 and -3.85 MHz was reached about 0.25 s after switching on the HF transmitter. In the following second the enhancement gradually decreased to about 3% and remained there until switching off. During the late afternoon, in the presence of photoelectrons, using the same HF power at 5.1 MHz, an initial enhancement by 25% of the backscattered power with Doppler shifts between -5.25 and -5.35 MHz appeared within less than 0.1 s after switching on the HF transmitter. The incoherent backscatter by Langmuir waves enhanced by photoelectrons was already above system noise by a factor greatly in excess of 10 before switching on the HF transmitter; the 25% enhancement thus corresponds to an enhancement greatly in excess of 250% above system noise. The enhancement drops to less than one tenth of its original value in less than a second. The nighttime effect is attributed to multiple acceleration of electrons from the high-energy tail of the Maxwellian distribution. The daytime effect is believed to be due to a modification in the distribution function of photoelectrons

  6. Scintillation arcs in low-frequency observations of the timing-array millisecond pulsar J0437-4715

    CERN Document Server

    Bhat, N D R; Tremblay, S E; McSweeney, S J; Tingay, S J

    2015-01-01

    Low-frequency observations of pulsars provide a powerful means for probing the microstructure in the turbulent interstellar medium (ISM). Here we report on high-resolution dynamic spectral analysis of our observations of the timing-array millisecond pulsar J0437-4715 with the Murchison Widefield Array (MWA), enabled by our recently commissioned tied-array beam processing pipeline for voltage data recorded from the high time resolution mode of the MWA. A secondary spectral analysis reveals faint parabolic arcs, akin to those seen in high-frequency observations of pulsars with the Green Bank and Arecibo telescopes. Data from Parkes observations at a higher frequency of 732 MHz reveal a similar parabolic feature, with a curvature that scales approximately as the square of the observing wavelength ($\\lambda^2$) to the MWA's frequency of 192 MHz. Our analysis suggests that scattering toward PSR J0437-4715 predominantly arises from a compact region about 115 pc from the Earth, which matches well with the expected l...

  7. ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. I. H I OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Giovanelli, Riccardo; Haynes, Martha P.; Adams, Elizabeth A. K. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Cannon, John M.; Bernstein-Cooper, Elijah Z. [Department of Physics and Astronomy, Macalester College, Saint Paul, MN 55105 (United States); Rhode, Katherine L.; Salzer, John J. [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Skillman, Evan D.; McQuinn, Kristen B. W., E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu, E-mail: betsey@astro.cornell.edu, E-mail: jcannon@macalester.edu, E-mail: ebernste@macalester.edu, E-mail: rhode@astro.indiana.edu, E-mail: slaz@astro.indiana.edu, E-mail: skillman@astro.umn.edu, E-mail: kmcquinn@astro.umn.edu [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States)

    2013-07-01

    The discovery of a previously unknown 21 cm H I line source identified as an ultra-compact high velocity cloud in the ALFALFA survey is reported. The H I detection is barely resolved by the Arecibo 305 m telescope {approx}4' beam and has a narrow H I linewidth (half-power full width of 24 km s{sup -1}). Further H I observations at Arecibo and with the Very Large Array corroborate the ALFALFA H I detection, provide an estimate of the H I radius, {approx}1' at the 5 Multiplication-Sign 10{sup 19} cm{sup -2} isophote, and show the cloud to exhibit a velocity field which, if interpreted as disk rotation, has an amplitude of {approx_equal}9.0 {+-} 1.5 km s{sup -1}. In other papers, Rhode et al. show the H I source to have a resolved stellar counterpart and ongoing star forming activity, while Skillman et al. reveal it as having extremely low metallicity: 12 + log (O/H) = 7.16 {+-} 0.04. The H I mass to stellar mass ratio of the object is found to be 2.6. We use the Tully-Fisher template relation in its baryonic form to obtain a distance estimate D{sub Mpc}=1.3{sup +0.9}{sub -0.5}. Additional constraints on the distance are also provided by the optical data of Rhode et al. and McQuinn et al., both indicating a distance in the range of 1.5 to 2.0 Mpc. The three estimates are compatible within their errors. The object appears to be located beyond the dynamical boundaries of, but still in close proximity to the Local Group. Its pristine properties are consistent with the sedate environment of its location. At a nominal distance of 1.75 Mpc, it would have an H I mass of {approx_equal} 1.0 Multiplication-Sign 10{sup 6} M {sub Sun }, a stellar mass of {approx_equal} 3.6 Multiplication-Sign 10{sup 5} M {sub Sun }, and a dynamical mass within the H I radius of {approx_equal} 1.5 Multiplication-Sign 10{sup 7} M {sub Sun }. This discovery supports the idea that optically faint-or altogether dark-low mass halos may be detectable through their non-stellar baryons.

  8. ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. I. H I OBSERVATIONS

    International Nuclear Information System (INIS)

    The discovery of a previously unknown 21 cm H I line source identified as an ultra-compact high velocity cloud in the ALFALFA survey is reported. The H I detection is barely resolved by the Arecibo 305 m telescope ∼4' beam and has a narrow H I linewidth (half-power full width of 24 km s–1). Further H I observations at Arecibo and with the Very Large Array corroborate the ALFALFA H I detection, provide an estimate of the H I radius, ∼1' at the 5 × 1019 cm–2 isophote, and show the cloud to exhibit a velocity field which, if interpreted as disk rotation, has an amplitude of ≅9.0 ± 1.5 km s–1. In other papers, Rhode et al. show the H I source to have a resolved stellar counterpart and ongoing star forming activity, while Skillman et al. reveal it as having extremely low metallicity: 12 + log (O/H) = 7.16 ± 0.04. The H I mass to stellar mass ratio of the object is found to be 2.6. We use the Tully-Fisher template relation in its baryonic form to obtain a distance estimate DMpc=1.3+0.9-0.5. Additional constraints on the distance are also provided by the optical data of Rhode et al. and McQuinn et al., both indicating a distance in the range of 1.5 to 2.0 Mpc. The three estimates are compatible within their errors. The object appears to be located beyond the dynamical boundaries of, but still in close proximity to the Local Group. Its pristine properties are consistent with the sedate environment of its location. At a nominal distance of 1.75 Mpc, it would have an H I mass of ≅ 1.0 × 106 M ☉, a stellar mass of ≅ 3.6 × 105 M ☉, and a dynamical mass within the H I radius of ≅ 1.5 × 107 M ☉. This discovery supports the idea that optically faint—or altogether dark—low mass halos may be detectable through their non-stellar baryons.

  9. Les observables

    Directory of Open Access Journals (Sweden)

    Bergounioux Gabriel

    2014-07-01

    jacents ? Au cours de cette table ronde, la question des observables sera interrogée en partant d’une réflexion concernant les études qui se fondent sur l’inventaire empirique des données pour construire leurs analyses (statistique lexicale, Labphon, corpus-guided linguistics, sociolinguistique variationniste, linguistique cognitive… et en allant jusqu’aux théories qui postulent l’existence de formalismes préalables dont les discours et les textes ratifieraient, par l’actualisation et la distribution de leurs occurrences, la pertinence épistémologique.

  10. Comparison of F-region electron density observations by satellite radio tomography and incoherent scatter methods

    Science.gov (United States)

    Nygrén, T.; Markkanen, M.; Lehtinen, M.; Tereshchenko, E. D.; Khudukon, B. Z.; Evstafiev, O. V.; Pollari, P.

    1996-12-01

    In November 1995 a campaign of satellite radiotomography supported by the EISCAT incoherent scatter radar and several other instruments was arranged in Scandinavia. A chain of four satellite receivers extending from the north of Norway to the south of Finland was installed approximately along a geomagnetic meridian. The receivers carried out difference Doppler measurements using signals from satellites flying along the chain. The EISCAT UHF radar was simultaneously operational with its beam swinging either in geomagnetic or in geographic meridional plane. With this experimental set-up latitudinal scans of F-region electron density are obtained both from the radar observations and by tomographic inversion of the phase observations given by the difference Doppler experiment. This paper shows the first results of the campaign and compares the electron densities given by the two methods. Acknowledgements. This work has been supported by the UK Particle-Physics and Astronomy Research Council. The assistance of the director and staff of the EISCAT Scientific Association, the staff of the Norsk Polarinstitutt and the director and staff of the Swedish Institute of Space Physics is gratefully acknowledged. In addition the authors would like to thank Professor Evgeny Tereshchenko of the Polar Geophysical Institute in Mumansk, Russia and Dr Tuomo Nygrén of the University of Oulu, Finland for provision of data from EISCAT special program time during the November 1995 campaign. Topical Editor D. Alcaydé thanks E. J. Fremouw and another referee for their help in evaluating this paper.--> Correspondence to: I. K. Walker-->

  11. Galaxy Populations and Evolution in Clusters IV Deep HI Observations of Dwarf Ellipticals in the Virgo Cluster

    CERN Document Server

    Conselice, C J; Gallagher, J S; Wyse, R F G; Conselice, Christopher J.; Neil, Karen O'; Gallagher, John S.; Wyse, Rosemary F.G.

    2003-01-01

    We present in this paper the deepest Arecibo HI observations of Virgo cluster dwarf ellipticals (dEs) taken to date. Based on this data we argue that a significant fraction of Virgo cluster dEs recently underwent evolution. Our new observations consist of HI 21-cm line observations for 22 classified dE galaxies with optical radial velocities consistent with membership in the Virgo cluster. Cluster members VCC 390 and VCC 1713 are detected with HI masses M(HI) = 6*10^7 M_solar and 8*10^7 M_solar, respectively, while M(HI) in the remaining 20 dE galaxies have upper limits as low as 5*10^5 M_solar. We combine our results with those for 27 other Virgo cluster dEs with HI observations in the literature, 7 of which have HI detection claims. New optical images from the WIYN telescope of 5 of these HI-detected dEs, along with archival data, suggest that seven of the claimed detections are real, yielding a ~ 15% detection rate. These HI-detected classified dEs are preferentially located near the periphery of the Virgo...

  12. Observational exobiology

    Science.gov (United States)

    Tarter, J.

    1986-01-01

    The Earth's atmosphere absorbs partially or completely many ultraviolet, infrared and submillimeter wavelengths. Atmospheric seeing distorts small images, imposing a limit on the achievable angular resolution at optical and infrared wavelengths that is much poorer than the intrinsic capability of telescope optics. The atomic and molecular species of the atmosphere confuse or prevent the spectral studies of similar compounds outside of the terrestrial environment. Telescopes placed in orbit above the atmosphere avoid these problems and enjoy a unique view of the universe. There are many complex questions pertaining to the origin and evolution of the biogenic elements and compounds and the existence of terrestrial types of planets elsewhere that can be only tackled from orbiting facilities. The detailed nature of the spacecraft, platforms and instrumentation most likely to be launched by the United States and Europe in the near future in an attempt to determine what observational programs would be tractable and which areas of interest to exobiology required hardware capabilities beyond those currently envisioned are considered.

  13. Multiwavelength Observations of the Redback Millisecond Pulsar J1048+2339

    Science.gov (United States)

    Deneva, J. S.; Ray, P. S.; Camilo, F.; Halpern, J. P.; Wood, K.; Cromartie, H. T.; Ferrara, E.; Kerr, M.; Ransom, S. M.; Wolff, M. T.; Chambers, K. C.; Magnier, E. A.

    2016-06-01

    We report on radio timing and multiwavelength observations of the 4.66 ms redback pulsar J1048+2339, which was discovered in an Arecibo search targeting the Fermi-Large Area Telescope source 3FGL J1048.6+2338. Two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar. PSR J1048+2339 is in a 6 hr binary and exhibits radio eclipses over half the orbital period and rapid orbital period variations. The companion has a minimum mass of 0.3 M ⊙, and we have identified a V ∼ 20 variable optical counterpart in data from several surveys. The phasing of its ∼1 mag modulation at the orbital period suggests highly efficient and asymmetric heating by the pulsar wind, which may be due to an intrabinary shock that is distorted near the companion, or to the companion’s magnetic field channeling the pulsar wind to specific locations on its surface. We also present gamma-ray spectral analysis of the source and preliminary results from searches for gamma-ray pulsations using the radio ephemeris.

  14. Multiwavelength Observations of the Redback Millisecond Pulsar J1048+2339

    CERN Document Server

    Deneva, J S; Camilo, F; Halpern, J P; Wood, K; Cromartie, H T; Ferrara, E; Kerr, M; Ransom, S M; Wolff, M T; Chambers, K C; Magnier, E A

    2016-01-01

    We report on radio timing and multiwavelength observations of the 4.66 ms redback pulsar J1048+2339, which was discovered in an Arecibo search targeting the Fermi-LAT source 3FGLJ1048.6+2338. Two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar. PSR J1048+2339 is in a 6-hour binary, and exhibits radio eclipses over half the orbital period and rapid orbital period variations. The companion has a minimum mass of 0.3 solar masses, and we have identified a $V \\sim 20$ variable optical counterpart in data from several surveys. The phasing of its $\\sim 1$~mag modulation at the orbital period suggests highly efficient and asymmetric heating by the pulsar wind, which may be due to an intrabinary shock that is distorted near the companion, or to the companion's magnetic field channeling the pulsar wind to specific locations on its surface. We also present gamma-ray spectral analysis of the source and preliminary results from searches for gamma-ray pulsations using the radi...

  15. Lower thermosphere coupling study: Comparison of observations with predictions of the University College London-Sheffield thermosphere-ionosphere model

    International Nuclear Information System (INIS)

    During the first Lower Thermosphere Coupling Study (LTCS), September 21-25 1987, data were recorded from the incoherent scatter radar sites at EISCAT, Millstone Hill, Sondrestrom, and Arecibo. These experimental facilities measured ionospheric parameters (Ne, Te, Ti, and plasma velocity) in the E and the F regions which have been used to determine the E region neutral wind and infer the neutral temperature in the height range 100-150 km. Propagating tides are clearly visible in some of the parameters, and the latitude structure and phase variations with height indicate the presence of at least the (2,2) and (2,4) global tidal Hough modes. The influence of geomagnetic forcing is also clearly present at high latitudes. The University College London-Sheffield University three-dimensional coupled thermosphere-ionosphere model has been used to simulate this period of observation, by imposing tidal forcing at the lower boundary and magnetospheric forcing at high latitudes, in an attempt to interpret and understand the experimental data. Model simulations are able to predict where the signature of a particular tidal mode is likely to be observed in the respective responses of the temperature and wind structure. The numerical simulations predict the range of observed tidal amplitudes at mid and high latitudes, provided the tidal forcing functions imposed near the lower boundary of the model are larger (400 m geopotential height variation) than those inferred from linear tidal models

  16. Validation of the CUTLASS HF radar gravity wave observing capability using EISCAT CP-1 data

    Directory of Open Access Journals (Sweden)

    N. F. Arnold

    Full Text Available Quasi-periodic fluctuations in the returned ground-scatter power from the SuperDARN HF radars have been linked to the passage of medium-scale gravity waves. We have applied a technique that extracts the first radar range returns from the F-region to study the spatial extent and characteristics of these waves in the CUTLASS field-of-view. Some ray tracing was carried out to test the applicability of this method. The EISCAT radar facility at Tromsø is well within the CUTLASS field-of-view for these waves and provides a unique opportunity to assess independently the ability of the HF radars to derive gravity wave information. Results from 1st March, 1995, where the EISCAT UHF radar was operating in its CP-1 mode, demonstrate that the radars were in good agreement, especially if one selects the electron density variations measured by EISCAT at around 235 km. CUTLASS and EISCAT gravity wave observations complement each other; the former extends the spatial field of view considerably, whilst the latter provides detailed vertical information about a range of ionospheric parameters.

    Key words. Ionosphere (ionosphere – atmosphere interactions · Meteorology and atmospheric dynamics (thermospheric dynamics · Radio science (ionospheric propagations

  17. Saturation and hysteresis effects in ionospheric modification experiments observed by the CUTLASS and EISCAT radars

    Directory of Open Access Journals (Sweden)

    D. M. Wright

    2006-03-01

    Full Text Available The results of high latitude ionospheric modification experiments utilising the EISCAT heating facility at Tromsø are presented. As a result of the interaction between the high power pump waves and upper hybrid waves in the ionosphere, field-aligned electron density irregularities are artificially excited. Observations of these structures with the CUTLASS coherent HF radars and the EISCAT incoherent UHF radar exhibit hysteresis effects as the heater output power is varied. These are explained in terms of the two-stage mechanism which leads to the growth of the irregularities. Experiments which involve preconditioning of the ionosphere also indicate that hysteresis could be exploited to maximise the intensity of the field-aligned irregularities, especially where the available heater power is limited.

    In addition, the saturation of the irregularity amplitude is considered. Although, the rate of irregularity growth becomes less rapid at high heater powers it does not seem to fully saturate, indicating that the amplification would continue beyond the capabilities of the Tromsø heater - currently the most powerful of its kind. It is shown that the CUTLASS radars are sensitive to irregularities produced by very low heater powers (effective radiated powers <4 MW. This fact is discussed from the perspective of a new heating facility, SPEAR, located on Spitzbergen and capable of transmitting high frequency radio waves with an effective radiated power ~10% of that of the Tromsø heater (28MW.

  18. HI Observations of the Ca II absorbing galaxies Mrk 1456 and SDSS J211701.26-002633.7

    CERN Document Server

    Cherinka, Brian; Rosenberg, Jessica

    2009-01-01

    In an effort to study Damped Lyman Alpha galaxies at low redshift, we have been using the Sloan Digital Sky Survey to identify galaxies projected onto QSO sightlines and to characterize their optical properties. For low redshift galaxies, the HI 21cm emission line can be used as an alternate tool for identifying possible DLA galaxies, since HI emitting galaxies typically exhibit HI columns that are larger than the classical DLA limit. Here we report on follow-up HI 21 cm emission line observations of two DLA candidates that are both low-redshift spiral galaxies, Mrk 1456 and SDSS J211701.26-002633.7. The observations were made using the Green Bank and Arecibo Telescopes, respectively. Analysis of their HI properties reveal the galaxies to be about one and two M_HI* galaxies, respectively, and to have average HI mass, gas-richness, and gas mass fraction for their morphological types. We consider Mrk 1456 and SDSS J211701.26-002633.7 to be candidate DLA systems based upon the strength of the CaII absorption lin...

  19. Modeling the Meteoroid Input Function at Mid-Latitude Using Meteor Observations by the MU Radar

    Science.gov (United States)

    Pifko, Steven; Janches, Diego; Close, Sigrid; Sparks, Jonathan; Nakamura, Takuji; Nesvorny, David

    2012-01-01

    The Meteoroid Input Function (MIF) model has been developed with the purpose of understanding the temporal and spatial variability of the meteoroid impact in the atmosphere. This model includes the assessment of potential observational biases, namely through the use of empirical measurements to characterize the minimum detectable radar cross-section (RCS) for the particular High Power Large Aperture (HPLA) radar utilized. This RCS sensitivity threshold allows for the characterization of the radar system s ability to detect particles at a given mass and velocity. The MIF has been shown to accurately predict the meteor detection rate of several HPLA radar systems, including the Arecibo Observatory (AO) and the Poker Flat Incoherent Scatter Radar (PFISR), as well as the seasonal and diurnal variations of the meteor flux at various geographic locations. In this paper, the MIF model is used to predict several properties of the meteors observed by the Middle and Upper atmosphere (MU) radar, including the distributions of meteor areal density, speed, and radiant location. This study offers new insight into the accuracy of the MIF, as it addresses the ability of the model to predict meteor observations at middle geographic latitudes and for a radar operating frequency in the low VHF band. Furthermore, the interferometry capability of the MU radar allows for the assessment of the model s ability to capture information about the fundamental input parameters of meteoroid source and speed. This paper demonstrates that the MIF is applicable to a wide range of HPLA radar instruments and increases the confidence of using the MIF as a global model, and it shows that the model accurately considers the speed and sporadic source distributions for the portion of the meteoroid population observable by MU.

  20. Morning sector drift-bounce resonance driven ULF waves observed in artificially-induced HF radar backscatter

    Directory of Open Access Journals (Sweden)

    L. J. Baddeley

    Full Text Available HF radar backscatter, which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsø, has provided coherent radar ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by both the CUTLASS HF radars and the EISCAT UHF radar. Data from the SP-UK-OUCH experiment have revealed small-scale (high azimuthal wave number, m -45 waves, predominantly in the morning sector, thought to be brought about by the drift-bounce resonance processes. Conjugate observations from the Polar CAM-MICE instrument indicate the presence of a non-Maxwellian ion distribution function. Further statistical analysis has been undertaken, using the Polar TIMAS instrument, to reveal the prevalence and magnitude of the non-Maxwellian energetic particle populations thought to be responsible for generating these wave types.

    Key words. Ionosphere (active experiments; wave-particle interactions Magnetospheric physics (MHD waves and instabilities

  1. Detection of the Earth with the SETI microwave observing system assumed to be operating out in the galaxy

    Science.gov (United States)

    Billingham, J.; Tarter, J.

    1992-01-01

    This paper estimates the maximum range at which radar signals from the Earth could be detected by a search system similar to the NASA Search for Extraterrestrial Intelligence Microwave Observing Project (SETI MOP) assumed to be operating out in the galaxy. Figures are calculated for the Targeted Search, and for the Sky Survey parts of the MOP, both operating, as currently planned, in the second half of the decade of the 1990s. Only the most powerful terrestrial transmitters are considered, namely, the planetary radar at Arecibo in Puerto Rico, and the ballistic missile early warning systems (BMEWS). In each case the probabilities of detection over the life of the MOP are also calculated. The calculation assumes that we are only in the eavesdropping mode. Transmissions intended to be detected by SETI systems are likely to be much stronger and would of course be found with higher probability to a greater range. Also, it is assumed that the transmitting civilization is at the same level of technological evolution as ours on Earth. This is very improbable. If we were to detect another technological civilization, it would, on statistical grounds, be much older than we are and might well have much more powerful transmitters. Both factors would make detection by the NASA MOP a much more likely outcome.

  2. Sistema de adquisición de datos para la medición de parámetros radioeléctricos en antenas lineales en la banda de TV de VHF y UHF System of acquisition of information for measurement of radioelectric parameters in linear antennas in the band of VHF and UHF’s television

    Directory of Open Access Journals (Sweden)

    María del Pilar Celemín

    2007-06-01

    Full Text Available Este proyecto desarrolla un sistema de adquisición y procesamiento de datos para la medición y ajuste de parámetros radioeléctricos de antenas lineales en las bandas de VHF y UHF. Como señal de prueba se utilizan algunas de las señales de televisión que se encuentran en el espectro radioeléctrico, provenientes de los transmisores que radian señales de canales nacionales. El receptor implementado incluye un sintonizador comercial de televisión que toma como muestra la señal portadora de video. Esta señal es amplificada, filtrada, almacenada y acondicionada, para ser leída por el puerto serial de un computador personal y procesada empleando un programa en Visual Basic, con una interfaz gráfica que permite una interacción amigable con el usuario. Desde acá se interactúa con un microcontrolador que controla el mecanismo de posicionamiento de la antena receptora por medio de una estructura electromecánica, que le permite ejecutar movimientos en dos grados de libertad: en azimut y en elevación. Con esto se logra un sistema capaz de determinar automáticamente el apuntamiento óptimo de la antena de acuerdo al máximo nivel de recepción de señal. Así mismo, se determinan parámetros propios de la antena tales como: el patrón de radiación (tanto en el plano horizontal como vertical, la ganancia directiva de la antena, la ganancia en cada uno de los puntos que conforman el plano principal, y otros parámetros de interés para el análisis de las características reales de antenas lineales.This project develops a data acquisition and processing system for measuring and adjusting lineal-antenna radioelectric parameters in VHF and UHF. Television signals are used as test signal. They can be found in radio electric spectrum, as they come from commercial transmitters that broadcast signals of national channels. The achieved receptor includes a television commercial tuner for obtaining video signal. Later, this signal is conditioning to

  3. Evaluation of Cloud-resolving and Limited Area Model Intercomparison Simulations using TWP-ICE Observations. Part 2: Rain Microphysics

    Energy Technology Data Exchange (ETDEWEB)

    Varble, Adam; Zipser, Edward J.; Fridlind, Ann; Zhu, Ping; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; Shipway, Ben; Williams, Christopher R.

    2014-12-27

    Ten 3D cloud-resolving model (CRM) simulations and four 3D limited area model (LAM) simulations of an intense mesoscale convective system observed on January 23-24, 2006 during the Tropical Warm Pool – International Cloud Experiment (TWP-ICE) are compared with each other and with observations and retrievals from a scanning polarimetric radar, co-located UHF and VHF vertical profilers, and a Joss-Waldvogel disdrometer in an attempt to explain published results showing a low bias in simulated stratiform rainfall. Despite different forcing methodologies, similar precipitation microphysics errors appear in CRMs and LAMs with differences that depend on the details of the bulk microphysics scheme used. One-moment schemes produce too many small raindrops, which biases Doppler velocities low, but produces rain water contents (RWCs) that are similar to observed. Two-moment rain schemes with a gamma shape parameter (μ) of 0 produce excessive size sorting, which leads to larger Doppler velocities than those produced in one-moment schemes, but lower RWCs than observed. Two moment schemes also produce a convective median volume diameter distribution that is too broad relative to observations and thus, may have issues balancing raindrop formation, collision coalescence, and raindrop breakup. Assuming a μ of 2.5 rather than 0 for the raindrop size distribution improves one-moment scheme biases, and allowing μ to have values greater than 0 may improve two-moment schemes. Under-predicted stratiform rain rates are associated with under-predicted ice water contents at the melting level rather than excessive rain evaporation, in turn likely associated with convective detrainment that is too high in the troposphere and mesoscale circulations that are too weak. In addition to stronger convective updrafts than observed, limited domain size prevents a large, well-developed stratiform region from developing in CRMs, while a dry bias in ECMWF analyses does the same to the LAMs.

  4. Observations of aspect sensitive RF-enhanced incoherent backscatter in the polar cap ionosphere

    Science.gov (United States)

    Dhillon, Ranvir; Robinson, T. R.; Yeoman, Timothy K.

    RF-induced plasma instabilities give rise to characteristic spectral enhancements in incoherent scatter spectra. The aspect sensitivity of these enhancements provides valuable information regarding the physical processes that occur within the RF-affected ionospheric patch. These direction-dependent signatures exhibit significant variability and help shed light on possible coupling between artificial field-aligned irregularities generated at the upper-hybrid height and RF-induced instabilities excited near the reflection height for O-mode-polarized radio waves. This directional dependence of RF-enhanced incoherent radar backscatter has been shown using data from the high-latitude ionosphere, and the significant features included consistent field-aligned signatures that may be related to the presence of artificial field-aligned irregularities. These earlier high-latitude results provided motivation for repeating the investigation in the different geophysical conditions that obtain in the polar cap ionosphere. The Space Plasma Exploration by Active Radar (SPEAR) facility is located within the polar cap and has provided observations of RF-enhanced ion and plasma line spectra recorded by the EISCAT Svalbard UHF incoherent scatter radar system (ESR), which is collocated with SPEAR. We present observations of aspect sensitive E-and F-region SPEAR-induced ion and plasma line enhance-ments from several directions in the magnetic meridian plane, centred on field-aligned. These enhancements indicate excitation of both the purely growing mode and the parametric decay instability, together with sporadic E-layer results that may indicate the presence of cavitons. We note consistent enhancements from field-aligned, vertical and also from 5 degrees south of field-aligned. We attribute the prevalence of vertical scatter to the importance of the Spitze region, and of that from field-aligned to possible wave/irregularity coupling.

  5. Observations and Modeling of the Green Ocean Amazon 2014/15: Parsivel2 Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Courtney [Texas A & M Univ., College Station, TX (United States)

    2016-07-01

    One of the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Parsivel2 disdrometers was deployed at the first ARM Mobile Facility (AMF1) T3 site in Manacapuru, Brazil at the beginning of the second Green Ocean Amazon (GoAmazon)2014/15 intensive operational period (IOP2) in September 2014 through the end of the field campaign in December 2015. The Parsivel2 provided one-minute drop-size distribution (DSD) observations that have already been used for a number of applications related to GoAmazon2014/15 science objectives. The first use was the creation of a reflectivity-rain rate (Z-R) relation enabling the calculation of rain rates from the Brazilian Sistema de Protecao da Amazonia (SIPAM) S-band operational radar in Manaus. The radar-derived rainfall is an important constraint for the variational analysis of a large-scale forcing data set, which was recently released for the two IOPs that took place in the 2014 wet and transition seasons, respectively. The SIPAM radar rainfall is also being used to validate a number of cloud-resolving model simulations being run for the campaign. A second use of the Parsivel2 DSDs has been to provide a necessary reference point to calibrate the vertical velocity retrievals from the AMF1 W Band ARM Cloud Radar (WACR) cloud-profiling and ultra-high-frequency (UHF) wind-profiling instruments. Accurate retrievals of in-cloud vertical velocities are important to understand the microphysical and kinematic properties of Amazonian convective clouds and their interaction with the land surface and atmospheric aerosols. Further use of the Parsivel2 DSD observations can be made to better understand precipitation characteristics and their variability during GoAmazon2014/15.

  6. Observations of HI absorbing gas in compact radio sources at cosmological redshifts

    NARCIS (Netherlands)

    Vermeulen, RC; Pihlstrom, YM; Tschager, W; de Vries, WH; Conway, JE; Barthel, PD; Baum, SA; Braun, R; Miley, GK; O'Dea, CP; Rottgering, HJA; Schilizzi, RT; Snellen, IAG; Taylor, GB

    2003-01-01

    We present an overview of the occurrence and properties of atomic gas associated with compact radio sources at redshifts up to z = 0.85. Searches for H I 21 cm absorption were made with the Westerbork Synthesis Radio Telescope at UHF-high frequencies (725 - 1200 MHz). Detections were obtained for 19

  7. Potentially Hazardous Asteroid (85989) 1999 JD6: Radar, Infrared, and Lightcurve Observations and a Preliminary Shape Model

    Science.gov (United States)

    Marshall, Sean E.; Howell, Ellen S.; Brozović, Marina; Taylor, Patrick A.; Campbell, Donald B.; Benner, Lance A. M.; Naidu, Shantanu P.; Giorgini, Jon D.; Jao, Joseph S.; Lee, Clement G.; Richardson, James E.; Rodriguez-Ford, Linda A.; Rivera-Valentin, Edgard G.; Ghigo, Frank; Kobelski, Adam; Busch, Michael W.; Pravec, Petr; Warner, Brian D.; Reddy, Vishnu; Hicks, Michael D.; Crowell, Jenna L.; Fernandez, Yanga R.; Vervack, Ronald J.; Nolan, Michael C.; Magri, Christopher; Sharkey, Benjamin; Bozek, Brandon

    2015-11-01

    We report observations of potentially hazardous asteroid (85989) 1999 JD6, which passed 0.048 AU from Earth (19 lunar distances) during its close approach on July 25, 2015. During eleven days between July 15 and August 4, 2015, we observed 1999 JD6 with the Goldstone Solar System Radar and with Arecibo Observatory's planetary radar, including bistatic reception of some Goldstone echoes at Green Bank. We obtained delay-Doppler radar images at a wide range of latitudes, with range resolutions varying from 7.5 to 150 meters per pixel, depending on the observing conditions. We acquired near-infrared spectra from the NASA InfraRed Telescope Facility (IRTF) on two nights in July 2015, at wavelengths from 0.75 to 5.0 microns, showing JD6's thermal emission. We also obtained optical lightcurves from Ondrejov Observatory (in 1999), Table Mountain Observatory (in 2000), and Palmer Divide Station (in 2015). Previous observers had suggested that 1999 JD6 was most likely an elongated object, based on its large lightcurve amplitude of 1.2 magnitudes (Szabo et al. 2001; Polishook and Brosch 2008; Warner 2014). The radar images reveal an elongated peanut-shaped object, with two lobes separated by a sharp concavity. JD6's maximum diameter is about two kilometers, and its larger lobe is approximately 50% longer than its smaller lobe. The larger lobe has a concavity on its end. We will present more details on the shape and rotation state of 1999 JD6, as well as its surface properties from optical and infrared data and thermal modeling.

  8. Evaluation of Cloud-Resolving and Limited Area Model Intercomparison Simulations Using TWP-ICE Observations. Part 2 ; Precipitation Microphysics

    Science.gov (United States)

    Varble, Adam; Zipser, Edward J.; Fridland, Ann M.; Zhu, Ping; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; Shipway, Ben; Williams, Christopher

    2014-01-01

    Ten 3-D cloud-resolving model (CRM) simulations and four 3-D limited area model (LAM) simulations of an intense mesoscale convective system observed on 23-24 January 2006 during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) are compared with each other and with observations and retrievals from a scanning polarimetric radar, colocated UHF and VHF vertical profilers, and a Joss-Waldvogel disdrometer in an attempt to explain a low bias in simulated stratiform rainfall. Despite different forcing methodologies, similar precipitation microphysics errors appear in CRMs and LAMs with differences that depend on the details of the bulk microphysics scheme used. One-moment schemes produce too many small raindrops, which biases Doppler velocities low, but produces rainwater contents (RWCs) that are similar to observed. Two-moment rain schemes with a gamma shape parameter (mu) of 0 produce excessive size sorting, which leads to larger Doppler velocities than those produced in one-moment schemes but lower RWCs. Two-moment schemes also produce a convective median volume diameter distribution that is too broad relative to observations and, thus, may have issues balancing raindrop formation, collision-coalescence, and raindrop breakup. Assuming a mu of 2.5 rather than 0 for the raindrop size distribution improves one-moment scheme biases, and allowing mu to have values greater than 0 may improve excessive size sorting in two-moment schemes. Underpredicted stratiform rain rates are associated with underpredicted ice water contents at the melting level rather than excessive rain evaporation, in turn likely associated with convective detrainment that is too high in the troposphere and mesoscale circulations that are too weak. A limited domain size also prevents a large, well-developed stratiform region like the one observed from developing in CRMs, although LAMs also fail to produce such a region.

  9. FPI observations of nighttime mesospheric and thermospheric winds in China and their comparisons with HWM07

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, W.; Xu, J.; Jiang, G.; Ma, R. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Liu, X. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Henan Normal Univ., Xinxiang (China). College of Mathematics and Information Science; Zhou, Q. [Zhengzhou Univ. (China). School of Electrical Engineering; Miami Univ., Oxford, OH (United States). Electrical and Computer Engineering Dept.

    2013-10-01

    We analyzed the nighttime horizontal neutral winds in the middle atmosphere ({proportional_to} 87 and {proportional_to} 98 km) and thermosphere ({proportional_to} 250 km) derived from a Fabry-Perot interferometer (FPI), which was installed at Xinglong station (40.2 N, 117.4 E) in central China. The wind data covered the period from April 2010 to July 2012. We studied the annual, semiannual and terannual variations of the midnight winds at {proportional_to} 87 km, {proportional_to} 98 km and {proportional_to} 250 km for the first time and compared them with Horizontal Wind Model 2007 (HWM07). Our results show the following: (1) at {proportional_to} 87 km, both the observed and model zonal winds have similar phases in the annual and semiannual variations. However, the HWM07 amplitudes are much larger. (2) At {proportional_to} 98 km, the model shows strong eastward wind in the summer solstice, resulting in a large annual variation, while the observed strongest component is semiannual. The observation and model midnight meridional winds agree well. Both are equatorward throughout the year and have small amplitudes in the annual and semiannual variations. (3) There are large discrepancies between the observed and HWM07 winds at {proportional_to} 250 km. This discrepancy is largely due to the strong semiannual zonal wind in the model and the phase difference in the annual variation of the meridional wind. The FPI annual variation coincides with the results from Arecibo, which has similar geomagnetic latitude as Xinglong station. In General, the consistency of FPI winds with model winds is better at {proportional_to} 87 and {proportional_to} 98 km than that at {proportional_to} 250 km. We also studied the seasonally and monthly averaged nighttime winds. The most salient features include the following: (1) the seasonally averaged zonal winds at {proportional_to} 87 and {proportional_to} 98 km typically have small variations throughout the night. (2) The model zonal and

  10. FPI observations of nighttime mesospheric and thermospheric winds in China and their comparisons with HWM07

    Directory of Open Access Journals (Sweden)

    W. Yuan

    2013-08-01

    Full Text Available We analyzed the nighttime horizontal neutral winds in the middle atmosphere (~ 87 and ~ 98 km and thermosphere (~ 250 km derived from a Fabry–Perot interferometer (FPI, which was installed at Xinglong station (40.2° N, 117.4° E in central China. The wind data covered the period from April 2010 to July 2012. We studied the annual, semiannual and terannual variations of the midnight winds at ~ 87 km, ~ 98 km and ~ 250 km for the first time and compared them with Horizontal Wind Model 2007 (HWM07. Our results show the following: (1 at ~ 87 km, both the observed and model zonal winds have similar phases in the annual and semiannual variations. However, the HWM07 amplitudes are much larger. (2 At ~ 98 km, the model shows strong eastward wind in the summer solstice, resulting in a large annual variation, while the observed strongest component is semiannual. The observation and model midnight meridional winds agree well. Both are equatorward throughout the year and have small amplitudes in the annual and semiannual variations. (3 There are large discrepancies between the observed and HWM07 winds at ~ 250 km. This discrepancy is largely due to the strong semiannual zonal wind in the model and the phase difference in the annual variation of the meridional wind. The FPI annual variation coincides with the results from Arecibo, which has similar geomagnetic latitude as Xinglong station. In General, the consistency of FPI winds with model winds is better at ~ 87 and ~ 98 km than that at ~ 250 km. We also studied the seasonally and monthly averaged nighttime winds. The most salient features include the following: (1 the seasonally averaged zonal winds at ~ 87 and ~ 98 km typically have small variations throughout the night. (2 The model zonal and meridional nighttime wind variations are typically much larger than those of observations at ~ 87 km and ~ 98 km. (3 At ~ 250 km, model zonal wind compares well with the observation in the winter. For spring and

  11. Observer's Interface for JWST Observation Specifications

    Science.gov (United States)

    Link, Miranda; Douglas, Robert; Moriarty, Christopher; Roman, Anthony

    2016-01-01

    In support of the launch of the James Webb Space Telescope, various teams at STScI (the Space Telescope Science Institute) have collaborated on how to re-structure the view of a an observing program within the Astronomer's Proposal Tool (APT) to accommodate for the differences between HST and JWST. For HST APT programs, the structure is visit-dominant, and there is one generic form for entering observing information that spans all instruments with their required fields and options. This can result in sometimes showing irrelevant fields to the user for a given observing goal. Also, the generation of mosaicked observations in HST requires the user to manually calculate the position of each tile within the mosaic, accounting for positional offsets and the roll of the telescope, which is a time consuming process. Now, for JWST programs in APT, the description of the observations has been segregated by instrument and mode into discrete observing templates. Each template's form allows instrument specific choices and displays of relevant information. APT will manually manage the number of visits needed to perform the observation. This is particularly useful for mosaics and dithering with JWST. For example, users will select how they would like a mosaic to be tiled at the observation level, and the visits are automatically created. In this, visits have been re-structured to be purely informational; all editing is done at the observation level. These options and concepts are illustrated to future users via the corresponding poster.

  12. Seasonal and diurnal variability of the meteor flux at high latitudes observed using PFISR

    Science.gov (United States)

    Sparks, J. J.; Janches, D.; Nicolls, M. J.; Heinselman, C. J.

    2009-05-01

    We report in this and a companion paper [Fentzke, J.T., Janches, D., Sparks, J.J., 2008. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.015] a complete seasonal study of the micrometeor input function (MIF) at high latitudes using meteor head-echo radar observations performed with the Poker Flat Incoherent Scatter Radar (PFISR). This flux is responsible for a number of atmospheric phenomena; for example, it could be the source of meteoric smoke that is thought to act as condensation nuclei in the formation of ice particles in the polar mesosphere. The observations presented here were performed for full 24-h periods near the summer and winter solstices and spring and autumn equinoxes, times at which the seasonal variability of the MIF is predicted to be large at high latitudes [Janches, D., Heinselman, C.J., Chau, J.L., Chandran, A., Woodman, R., 2006. Modeling of the micrometeor input function in the upper atmosphere observed by High Power and Large Aperture Radars, JGR, 11, A07317, doi:10.1029/2006JA011628]. Precise altitude and radar instantaneous line-of-sight (radial) Doppler velocity information are obtained for each of the hundreds of events detected every day. We show that meteor rates, altitude, and radial velocity distributions have a large seasonal dependence. This seasonal variability can be explained by a change in the relative location of the meteoroid sources with respect to the observer. Our results show that the meteor flux into the upper atmosphere is strongly anisotropic and its characteristics must be accounted for when including this flux into models attempting to explain related aeronomical phenomena. In addition, the measured acceleration and received signal strength distribution do not seem to depend on season; which may suggest that these observed

  13. First electron density and temperature estimates from the Swarm Langmuir probes and a comparison with IS measurements

    Science.gov (United States)

    Buchert, Stephan C.; Eriksson, Anders; Gill, Reine; Nilsson, Thomas; Åhlen, Lennart; Wahlund, Jan-Erik; Knudsen, David; Burchill, Johnathan; Archer, William; Kouznetsov, Alexei; Stricker, Nico; Bouridah, Abderrazak; Bock, Ralph; Häggström, Ingemar; Rietveld, Michael; Gonzalez, Sixto; Aponte, Nestor

    2014-05-01

    The Langmuir Probes (LP) on the Swarm satellites are part of the Electric Field Instruments (EFI), which are featuring thermal ion imagers (TII) and so are measuring 3-d ion distributions. The main task of the Langmuir probes is to provide measurements of spacecraft potentials influencing the ions before they enter the TIIs. In addition also electron density (Ne) and temperature (Te) are estimated from EFI LP data. The design of the Swarm LP includes a standard current sampling under sweeps of the bias voltage, and also a novel ripple technique yielding derivatives of the current-voltage characteristics at three points in a rapid cycle. In normal mode the time resolution of the Ne and Te measurements so becomes only 0.5 s. We show first Ne and Te estimates from the EFI LPs obtained in the commissioning phase in December 2013, when all three satellites were following each other at about 500 km altitude at mutual distances of a few tens of kilometers. The LP data are compared with observations by incoherent scatter radars, namely EISCAT UHF, VHF, the ESR, and also Arecibo. Acknowledgements: The EFIs were developed and built by a consortium that includes COM DEV Canada, the University of Calgary, and the Swedish Institute for Space Physics in Uppsala. The Swarm EFI project is managed and funded by the European Space Agency with additional funding from the Canadian Space Agency. EISCAT is an international association supported by research organisations in China (CRIRP), Finland (SA), Japan (NIPR and STEL), Norway (NFR), Sweden (VR), and the United Kingdom (NERC). The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation (AST-1100968), and in alliance with Ana G. Méndez-Universidad Metropolitana, and the Universities Space Research Association.

  14. The composition of M-type asteroids: Synthesis of spectroscopic and radar observations

    Science.gov (United States)

    Ockert-Bell, M. E.; Clark, B. E.; Shepard, M. K.; Isaacs, R. A.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

    2010-12-01

    We have conducted a radar-driven observational campaign of 22 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Sixteen of our targets were near-simultaneously observed with radar and those observations are described in a companion paper (Shepard, M.K., and 19 colleagues [2010]. Icarus, in press). We find that most of the highest metal-content asteroids, as suggested by radar, tend to exhibit silicate absorption features at both 0.9 and 1.9 μm, and the lowest metal-content asteroids tend to exhibit either no bands or only the 0.9 μm band. Eleven of the asteroids were observed at several rotational longitudes in the near-infrared and significant variations in continuum slope were found for nine in the spectral regions 1.1-1.45 μm and 1.6-2.3 μm. We utilized visible wavelength data (Bus, S.J., Binzel, R.P. [2002b]. Icarus 158, 146-177; Fornasier, S., Clark, B.E., Dotto, E., Migliorini, A., Ockert-Bell, M., Barucci, M.A. [2010]. Icarus 210, 655-673.) for a more complete compositional analysis of our targets. Compositional evidence is derived from our target asteroid spectra using two different methods: (1) a χ2 search for spectral matches in the RELAB database, and (2) parametric comparisons with meteorites. This paper synthesizes the results of the RELAB search and the parametric comparisons with compositional suggestions based on radar observations. We find that for six of the seven asteroids with the highest iron abundances, our spectral results are consistent with the radar evidence (16 Psyche, 216 Kleopatra, 347 Pariana, 758 Mancunia, 779 Nina, and 785 Zwetana). Three of the seven asteroids with the lowest metal abundances, our spectral results are consistent with the radar evidence (21 Lutetia, 135 Hertha, 497 Iva). The remaining seven asteroids (22 Kalliope, 97 Klotho, 110 Lydia, 129 Antigone, 224 Oceana, 678 Fredegundis, and 771

  15. Excitation of Alfvén waves by modulated HF heating of the ionosphere, with application to FAST observations

    Directory of Open Access Journals (Sweden)

    E. Kolesnikova

    Full Text Available During the operation of the EISCAT high power facility (heater at Tromsø, Norway, on 8 October 1998, the FAST spacecraft made electric field and particle observations in the inner magnetosphere at 0.39 Earth radii above the heated ionospheric region. Measurements of the direct current electric field clearly exhibit oscillations with a frequency close to the modulated frequency of heater ( ~ 3 Hz and an amplitude of ~ 2 - 5 mV m-1. Thermal electron data from the electrostatic analyser show the modulation at the same frequency of the downward electron fluxes. During this period the EISCAT UHF incoherent scatter radar, sited also at Tromsø, measured a significant enhancement of the electron density in E-layer up to 2 · 1012 m-3. These observations have prompted us to make quantitative estimates of the expected pulsations in the inner magnetosphere caused by the modulated HF heating of lower ionosphere. Under the conditions of the strong electron precipitation in the ionosphere, which took place during the FAST observations, the primary current caused by the perturbation of the conductivity in the heated region is closed entirely by the parallel current which leaks into the magnetosphere. In such circumstances the conditions at the ionosphere-magnetosphere boundary are most favourable for the launching of an Alfvén wave: it is launched from the node in the gradient of the scalar potential which is proportional to the parallel current. The parallel electric field of the Alfvén wave is significant in the region where the electron inertial length is of order of the transverse wavelength of the Alfvén wave or larger and may effectively accelerate superthermal electrons downward into the ionosphere.

    Key words. Ionosphere (active experiments; ionosphere – magnetosphere interactions; particle acceleration

  16. Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars

    Science.gov (United States)

    Janches, Diego; Heinselman, Craig J.; Chau, Jorge L.; Chandran, Amal; Woodman, Ronald

    2006-07-01

    We report initial results of an effort to model the diurnal and seasonal variability of the meteor rate detected by high power and large aperture (HPLA) radars. The model uses Monte Carlo simulation techniques and at present assumes that most of the detected particles originate from three radiant distributions with the most dominant concentrated around the Earth's apex. The other two sources are centered 80° in ecliptic longitude to each side of the apex and are commonly known as helion and antihelion. To reproduce the measurements, the apex source flux was set to provide ˜70% of the total number of particles while the other ˜30% is provided by the combined contribution of the two remaining sources. The results of the model are in excellent agreement with observed diurnal curves obtained at different seasons and locations using the 430 MHz Arecibo radar in Puerto Rico, the 50 MHz Jicamarca radar in Perú, and the 1.29 GHz Sondrestrom radar in Greenland. To obtain agreement with the observed diurnal and seasonal variability of the meteor rate, an empirical atmospheric filtering effect was introduced in the simulation which prevents meteors with low-elevation radiants (≤20°) from being detected by the radars at mesospheric altitudes. The filtering effect is probably produced by a combination of factors related to the interaction of the meteor with the air molecules such as electron production and/or the ablation at higher altitudes. On the basis of these results we calculate the micrometeor global, diurnal, and seasonal input in the upper atmosphere.

  17. Excitation thresholds of field-aligned irregularities and associated ionospheric hysteresis at very high latitudes observed using SPEAR-induced HF radar backscatter

    Directory of Open Access Journals (Sweden)

    D. M. Wright

    2009-07-01

    Full Text Available On 10 October 2006 the SPEAR high power radar facility was operated in a power-stepping mode where both CUTLASS radars were detecting backscatter from the SPEAR-induced field-aligned irregularities (FAIs. The effective radiated power of SPEAR was varied from 1–10 MW. The aim of the experiment was to investigate the power thresholds for excitation (Pt and collapse (Pc of artificially-induced FAIs in the ionosphere over Svalbard. It was demonstrated that FAI could be excited by a SPEAR ERP of only 1 MW, representing only 1/30th of SPEAR's total capability, and that once created the irregularities could be maintained for even lower powers. The experiment also demonstrated that the very high latitude ionosphere exhibits hysteresis, where the down-going part of the power cycle provided a higher density of irregularities than for the equivalent part of the up-going cycle. Although this second result is similar to that observed previously by CUTLASS in conjunction with the Tromsø heater, the same is not true for the equivalent incoherent scatter measurements. The EISCAT Svalbard Radar (ESR failed to detect any hysteresis in the plasma parameters over Svalbard in stark contract with the measurements made using the Tromsø UHF.

  18. Passive UHF RFID tag with multiple sensing capabilities.

    Science.gov (United States)

    Fernández-Salmerón, José; Rivadeneyra, Almudena; Martínez-Martí, Fernando; Capitán-Vallvey, Luis Fermín; Palma, Alberto J; Carvajal, Miguel A

    2015-01-01

    This work presents the design, fabrication, and characterization of a printed radio frequency identification tag in the ultra-high frequency band with multiple sensing capabilities. This passive tag is directly screen printed on a cardboard box with the aim of monitoring the packaging conditions during the different stages of the supply chain. This tag includes a commercial force sensor and a printed opening detector. Hence, the force applied to the package can be measured as well as the opening of the box can be detected. The architecture presented is a passive single-chip RFID tag. An electronic switch has been implemented to be able to measure both sensor magnitudes in the same access without including a microcontroller or battery. Moreover, the chip used here integrates a temperature sensor and, therefore, this tag provides three different parameters in every reading. PMID:26506353

  19. Passive UHF RFID Tag with Multiple Sensing Capabilities

    Directory of Open Access Journals (Sweden)

    José Fernández-Salmerón

    2015-10-01

    Full Text Available This work presents the design, fabrication, and characterization of a printed radio frequency identification tag in the ultra-high frequency band with multiple sensing capabilities. This passive tag is directly screen printed on a cardboard box with the aim of monitoring the packaging conditions during the different stages of the supply chain. This tag includes a commercial force sensor and a printed opening detector. Hence, the force applied to the package can be measured as well as the opening of the box can be detected. The architecture presented is a passive single-chip RFID tag. An electronic switch has been implemented to be able to measure both sensor magnitudes in the same access without including a microcontroller or battery. Moreover, the chip used here integrates a temperature sensor and, therefore, this tag provides three different parameters in every reading.

  20. Electrical model simulation for a UHF RFID system

    OpenAIRE

    Abou Chakra, Sara; Farrukh, Usamah O.; Amante García, Beatriz

    2009-01-01

    Radio Frequency IDentification (RFID) deployment is needed for efficient item identification. A simulation environment in HP-ADS (Advanced Design System of Agilent Technologies) of Ultra High Frequency RFID systems is constructed in this paper. This paper simulates the system through an electrical model. The tag is represented by a simple empirical model representing the antenna by an amplifier and the chip. The chip is modeled by its impedance which varies with the...

  1. DCSK Multi-Access Scheme for UHF RFID System

    Directory of Open Access Journals (Sweden)

    Keqiang Yue

    2014-04-01

    Full Text Available DCSK modulation in chaos communication is a robust non-coherent modulation scheme. In this paper, the multiple-access DCSK scheme based on the OVSF code is proposed. Using the multiple-access DCSK scheme in RFID system, a DCSK-RFID system is presented. In the presented DCSK-RFID system, we use the DCSK for tag modulation for its low complexity and the simple receiver of the DCSK scheme is applied in reader part. The tag’s BER performance of the proposed DCSK-RFID system is carefully generalized both in theoretic analysis and in simulations. From the simulation results, the theoretical and simulation values match closely with each other. Then, we design an anti-collision MAC protocol based on multi-access DCSK-RFID scheme. We theoretically analyze the throughout in given number of tags. The simulation shows that the proposed algorithm has better throughout than S-Aloha system

  2. Experimental study of energy harvesting in UHF band

    Science.gov (United States)

    Bernacki, Ł.; Gozdur, R.; Salamon, N.

    2016-04-01

    A huge progress of down-sizing technology together with trend of decreasing power consumption and, on the other hand, increasing efficiency of electronics give the opportunity to design and to implement the energy harvesters as main power sources. This paper refers to the energy that can be harvested from electromagnetic field in the unlicensed frequency bands. The paper contains description of the most popular techniques and transducers that can be applied in energy harvesting domain. The overview of current research and commercial solutions was performed for bands in ultra-high frequency range, which are unlicensed and where transmission is not limited by administrative arrangements. During the experiments with Powercast’s receiver, the same bands as sources of electromagnetic field were taken into account. This power source is used for conducting radio-communication process and excess energy could be used for powering the extra electronic circuits. The paper presents elaborated prototype of energy harvesting system and the measurements of power harvested in ultra-high frequency range. The evaluation of RF energy harvesters for powering ultra-low power (ULP) electronic devices was performed based on survey and results of the experiments.

  3. VHF/UHF filters and multicouplers application of air resonators

    CERN Document Server

    Piette, Bernard

    2013-01-01

    This book describes the various devices used in radio communication and broadcasting to achieve high selectivity filtering and coupling. After providing a background in the basics of microwave theory and more detailed material - including a special chapter on precision and errors in measurement - the reader will find detailed descriptions, manufacturing processes, and, for the most useful instances, a number of worked-through formulas, which will allow engineers and technicians to design circuits or components for filtering or coupling applications. Content is covered in this format across a b

  4. Mixing height measurements from UHF wind profiling radar

    Energy Technology Data Exchange (ETDEWEB)

    Angevine, W.M.; Grimsdell, A.W. [CIRES, Univ. of Colorado, and NOAA Aeronomy Lab., Boulder, Colorado (United States)

    1997-10-01

    Mixing height in convective boundary layers can be detected by wind profiling radars (profilers) operating at or near 915 MHZ. We have made such measurements in a variety of settings including Alabama in 1992; Nova Scotia, Canada, during the North Atlantic Regional Experiment (NARE) 1993; Tennessee during the Southern Oxidant Study (SOS) 1994; near a 450 m tower in Wisconsin in 1995; and extensively in Illinois during the Flatland95, `96, and `97 experiments, as well as continuous operations at the Flatland Atmospheric Observatory. Profiler mixing height measurements, like all measurements, are subject to some limitations. The most important of these are due to rainfall, minimum height, and height resolution. Profilers are very sensitive to rain, which dominates the reflectivity and prevents the mixing height from being detected. Because the best height resolution is currently 60 m and the minimum height is 120-150 m AGL, the profiler is not suited for detecting mixing height in stable or nocturnal boundary layers. Problems may also arise in very dry or cold environments. (au) 12 refs.

  5. Uruguay - Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface weather observation forms for 26 stations in Uruguay. Period of record 1896-2005, with two to eight observations per day. Files created through a...

  6. Lightship Monthly Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Daily Weather Observations (Monthly Form 1001) from lightship stations in the United States. Please see the 'Surface Weather Observations (1001)' library for more...

  7. Surface Weather Observations Hourly

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard hourly observations taken at Weather Bureau/National Weather Service offices and airports throughout the United States. Hourly observations began during...

  8. Regional National Cooperative Observer

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA publication dedicated to issues, news and recognition of observers in the National Weather Service Cooperative Observer program. Issues published regionally...

  9. Monthly Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly Weather Observations (Form 1001) is a set of historical manuscript records for the period 1893-1948. In order to fill in the observation gap prior to the...

  10. Observing in school geometry

    OpenAIRE

    Zupan, Karmen

    2013-01-01

    Observing is an important process in learning geometry. In the first part of the thesis observing is considered from a psychological perspective: the Gestalt theory, its history, the distribution of gestalt qualities, as well as various studies and theories of templates. The observing process is considered also from the didactic point of view by means of the van Hiele’s theory of levels of geometric reasoning. Since colours also influence observing, a list of advices for teachers about using ...

  11. Learning by observing

    OpenAIRE

    Efe Postalci

    2010-01-01

    We introduce a network formation model based on the idea that individuals engage in production (or decide to participate in an action) depending on the similar actions of the people they observe in a society. We differentiate from the classical models of participation by letting individuals to choose, non cooperatively, which agents to observe. Observing behavior of others is a costly activity but provides benefits in terms of reduction in cost of production for the observing agent, which we ...

  12. Cloning of observables

    OpenAIRE

    Ferraro, Alessandro; Galbiati, Matteo; Paris, Matteo G. A.

    2005-01-01

    We introduce the concept of cloning for classes of observables and classify cloning machines for qubit systems according to the number of parameters needed to describe the class under investigation. A no-cloning theorem for observables is derived and the connections between cloning of observables and joint measurements of noncommuting observables are elucidated. Relationships with cloning of states and non-demolition measurements are also analyzed.

  13. Log-concave Observers

    OpenAIRE

    Henningsson, Toivo; Åström, Karl Johan

    2006-01-01

    The Kalman filter is the optimal state observer in the case of linear dynamics and Gaussian noise. In this paper, the observer problem is studied when process noise and measurements are generalized from Gaussian to log-concave. This generalization is of interest for example in the case where observations only give information that the signal is in a given range. It turns out that the optimal observer preserves log-concavity. The concept of strong log-concavity is ...

  14. Radioactive sampler observation device

    International Nuclear Information System (INIS)

    When an object of observation is a fuel rod and if a specimen in a fuel pool is small, it takes much labor for the observation and micro-observation images at a high ratio can not be displayed. A pipe for containing an observing camera in a water-sealed state, a jack capable of adjusting the focus of the observation camera by remote control and a horizontal bed capable of controlling the position of the observation camera for observing the specimen are disposed on a rail formed on lead block shielding walls. The magnification ratio for the observation can be increased by exchanging a die for securing the specimen and a lens, and a transparent acrylic resin plate, or a transparent lead-incorporated glass plate is joined to the bottom of the pipe. Since the sampled specimen can be observed as it is irrespective of the shape or the size of the specimen to be observed, danger of radiation exposure caused such as upon cutting, transportation or fabrication of the radioactive specimen can be reduced. Further, observation underwater can be conducted by the water sealing treatment of the pipe for the observing camera. (N.H.)

  15. Observation of online communities

    DEFF Research Database (Denmark)

    Nørskov, Sladjana V.; Rask, Morten

    2011-01-01

    This paper addresses the application of observation to online settings with a special focus on observer roles. It draws on a study of online observation of a virtual community, i.e. an open source software (OSS) community. The paper examines general and specific advantages and disadvantages of the...... observer roles in online settings by relating these roles to the same roles assumed in offline settings. The study suggests that under the right circumstances online and offline observation may benefit from being combined as they complement each other well. Quality issues and factors important to elicit...... trustworthy observational data from online study settings, such as OSS communities, are discussed. A proposition is made concerning how threats to credibility and transferability in relation to online observation (i.e. lack of richness and detail, risk of misunderstandings) can be diminished, while...

  16. BOOK REVIEW: Observational Cosmology Observational Cosmology

    Science.gov (United States)

    Howell, Dale Andrew

    2013-04-01

    Observational Cosmology by Stephen Serjeant fills a niche that was underserved in the textbook market: an up-to-date, thorough cosmology textbook focused on observations, aimed at advanced undergraduates. Not everything about the book is perfect - some subjects get short shrift, in some cases jargon dominates, and there are too few exercises. Still, on the whole, the book is a welcome addition. For decades, the classic textbooks of cosmology have focused on theory. But for every Sunyaev-Zel'dovich effect there is a Butcher-Oemler effect; there are as many cosmological phenomena established by observations, and only explained later by theory, as there were predicted by theory and confirmed by observations. In fact, in the last decade, there has been an explosion of new cosmological findings driven by observations. Some are so new that you won't find them mentioned in books just a few years old. So it is not just refreshing to see a book that reflects the new realities of cosmology, it is vital, if students are to truly stay up on a field that has widened in scope considerably. Observational Cosmology is filled with full-color images, and graphs from the latest experiments. How exciting it is that we live in an era where satellites and large experiments have gathered so much data to reveal astounding details about the origin of the universe and its evolution. To have all the latest data gathered together and explained in one book will be a revelation to students. In fact, at times it was to me. I've picked up modern cosmological knowledge through a patchwork of reading papers, going to colloquia, and serving on grant and telescope allocation panels. To go back and see them explained from square one, and summarized succinctly, filled in quite a few gaps in my own knowledge and corrected a few misconceptions I'd acquired along the way. To make room for all these graphs and observational details, a few things had to be left out. For one, there are few derivations

  17. The Observer Strikes Back

    CERN Document Server

    Hartle, James

    2015-01-01

    In the modern quantum mechanics of cosmology observers are physical systems within the universe. They have no preferred role in the formulation of the theory nor in its predictions of third person probabilities of what occurs. However, observers return to importance for the prediction of first person probabilities for what we observe of the universe: What is most probable to be observed is not necessarily what is most probable to occur. This essay reviews the basic framework for the computation of first person probabilities in quantum cosmology starting with an analysis of very simple models. It is shown that anthropic selection is automatic in this framework, because there is no probability for us to observe what is where we cannot exist. First person probabilities generally favor larger universes resulting from inflation where there are more places for us to be. In very large universes it is probable that our observational situation is duplicated elsewhere. The calculation of first person probabilities then...

  18. Does Observation Influence Learning?

    OpenAIRE

    Olivier Armantier

    2001-01-01

    A common value auction experiment is run to compare the relative influence of observation and experience on learning. It is shown that the ex-post observation of opponents' actions and payoffs homogenizes behavior and accelerates learning toward the Nash equilibrium. Besides, experiential and observational learning are both relevant and of comparable magnitude. A general reinforcement model for continuous strategies, encompassing choice reinforcement learning, direction learning and payoff de...

  19. Observables on Quantum Structures

    OpenAIRE

    Dvurečenskij, Anatolij; Kuková, Mária

    2012-01-01

    An observable on a quantum structure is any $\\sigma$-homomorphism of quantum structures from the Borel $\\sigma$-algebra into the quantum structure. We show that our partial information on an observable known only for all intervals of the form $(-\\infty,t)$ is sufficient to determine uniquely the whole observable defined on quantum structures like $\\sigma$-MV-algebras, $\\sigma$-effect algebras, Boolean $\\sigma$-algebras, monotone $\\sigma$-complete effect algebras with the Riesz Decomposition P...

  20. How observers create reality

    CERN Document Server

    Josephson, Brian D

    2015-01-01

    Wheeler proposed that repeated acts of observation give rise to the reality that we observe, but offered no detailed mechanism for this. Here this creative process is accounted for on the basis of the idea that nature has a deep technological aspect that evolves as a result of selection processes that act upon observers making use of the technologies. This leads to the conclusion that our universe is the product of agencies that use these evolved technologies to suit particular purposes.

  1. Jupiter System Observer

    Science.gov (United States)

    Senske, Dave; Kwok, Johnny

    2008-01-01

    This slide presentation reviews the proposed mission for the Jupiter System Observer. The presentation also includes overviews of the mission timeline, science goals, and spacecraftspecifications for the satellite.

  2. Automated Weather Observing System

    Data.gov (United States)

    Department of Transportation — The Automated Weather Observing System (AWOS) is a suite of sensors, which measure, collect, and disseminate weather data to help meteorologists, pilots, and flight...

  3. Aerosol Observation System

    Data.gov (United States)

    Oak Ridge National Laboratory — The aerosol observation system (AOS) is the primary Atmospheric Radiation Measurement (ARM) platform for in situ aerosol measurements at the surface. The principal...

  4. Turbulence Heating ObserveR - THOR

    Science.gov (United States)

    Retino, Alessandro; Marcucci, Maria FedericaFederica; Vaivads, Andris; Escoubet, C. Philippe; Khotyaintsev, Yuri; Fazakerley, Andrew; Soucek, Jan; Gehler, Martin; Lavraud, Benoit; Vainio, Rami; Valentini, Francesco; Chen, Christopher H. K.; Narita, Yasuhito; Wielders, Arno

    2016-07-01

    Turbulent fluctuations are ubiquitous in astrophysical plasmas and reach up to scales as large as stars, bubbles or clouds blown out by stellar winds, or even entire galaxies. However, most of the irreversible energy dissipation produced by turbulent fluctuations occurs at very small scales, the so-called kinetic scales, where the plasma no longer behaves as a fluid and the properties of individual plasma species (electrons, protons, and other ions) become important. The heating of different plasma species as well as the acceleration of particles to high energies are governed by kinetic processes which determine how the turbulent electromagnetic fluctuations dissipate. Thus, processes at kinetic scales directly affect the large-scale properties of astrophysical plasmas. Turbulence Heating ObserveR (THOR) is the first mission ever flown in space fully dedicated to study plasma turbulent fluctuations and associated energization mechanisms. It will explore the kinetic plasma processes that determine the fundamental behavior of the majority of baryonic matter in the universe. THOR will lead to an understanding of the basic plasma heating and particle acceleration mechanisms, of their effect on different plasma species and of their relative importance in different turbulent regimes. THOR will provide closure of these fundamental questions by making detailed in situ measurements of the closest available dilute and turbulent magnetized plasmas at unprecedented temporal and spatial resolution. THOR focuses on particular regions in space: the pristine solar wind, the Earth's bow shock and interplanetary shocks, and the compressed solar wind regions downstream of shocks. These regions are selected because of their different turbulence properties, and reflect similar astrophysical environments. THOR is a candidate for selection as the next ESA M4 mission. Here we present THOR's science as well as the results of the ongoing mission study, currently undertaken at ESA.

  5. Observer-dependent entanglement

    International Nuclear Information System (INIS)

    Understanding the observer-dependent nature of quantum entanglement has been a central question in relativistic quantum information. In this paper, we will review key results on relativistic entanglement in flat and curved spacetime and discuss recent work which shows that motion and gravity have observable effects on entanglement between localized systems. (paper)

  6. Observer dependent entanglement

    OpenAIRE

    Alsing, Paul M.; Fuentes, Ivette

    2012-01-01

    Understanding the observer-dependent nature of quantum entanglement has been a central question in relativistic quantum information. In this paper we will review key results on relativistic entanglement in flat and curved spacetime and discuss recent work which shows that motion and gravity have observable effects on entanglement between localized systems.

  7. Deltagende observation 2. udgave

    DEFF Research Database (Denmark)

    Kristiansen, Søren; Krogstrup, Hanne Kathrine

    Denne bog er en teoretisk og praktisk introduktion til deltagende observation, og giver konkrete anvisninger, som er nyttige for såvel erfarne som den uprøvede feltforsker.......Denne bog er en teoretisk og praktisk introduktion til deltagende observation, og giver konkrete anvisninger, som er nyttige for såvel erfarne som den uprøvede feltforsker....

  8. Participation beyond observation

    DEFF Research Database (Denmark)

    Chimirri, Niklas Alexander

    , however, the researchers typically uphold the notion that all they methodically engage in is participant observation. The paper argues that important aspects of children’s living and understanding may be lost when considering them mere objects of one’s visual and verbal research practices. First I delve...... on investigating children’s perspectives through participant observation, but also ontological and political ones....

  9. Observe Your Shadow

    Science.gov (United States)

    Rovšek, Barbara

    2016-01-01

    Observe Your Shadow was the title of an observational experiment that was, among others, conducted in the scope of the past year's (2014-2015) first Slovene science competition for elementary school pupils between the ages of 6 and 13. The main reason for establishing a new science competition was popularization of science and its experimental…

  10. Maximally incompatible quantum observables

    International Nuclear Information System (INIS)

    The existence of maximally incompatible quantum observables in the sense of a minimal joint measurability region is investigated. Employing the universal quantum cloning device it is argued that only infinite dimensional quantum systems can accommodate maximal incompatibility. It is then shown that two of the most common pairs of complementary observables (position and momentum; number and phase) are maximally incompatible.

  11. Maximally incompatible quantum observables

    Energy Technology Data Exchange (ETDEWEB)

    Heinosaari, Teiko, E-mail: teiko.heinosaari@utu.fi [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Schultz, Jussi, E-mail: jussi.schultz@gmail.com [Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Toigo, Alessandro, E-mail: alessandro.toigo@polimi.it [Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ziman, Mario, E-mail: ziman@savba.sk [RCQI, Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava (Slovakia); Faculty of Informatics, Masaryk University, Botanická 68a, 60200 Brno (Czech Republic)

    2014-05-01

    The existence of maximally incompatible quantum observables in the sense of a minimal joint measurability region is investigated. Employing the universal quantum cloning device it is argued that only infinite dimensional quantum systems can accommodate maximal incompatibility. It is then shown that two of the most common pairs of complementary observables (position and momentum; number and phase) are maximally incompatible.

  12. Working Group 1: Observations

    International Nuclear Information System (INIS)

    Topics of discussion include the following: the need for observations; issues in establishing global climate trends; climate variables such as surface air temperature over land, marine temperature, precipitation, circulation, upper air measurements, historical observations, subsurface ocean data, sea level, cryosphere, clouds, solar radiation, and aerosols; future considerations and recommendations which focuses on the establishment of a global benchmark climate monitoring network and data management

  13. An observable entanglement measure

    International Nuclear Information System (INIS)

    Although entanglement constitutes one of the most remarkable differences between classical and quantum mechanics, and it does have directly observable consequences, it is not an observable like for example momentum or energy. Unlike a regular observable that has an associated hermitean operator, an entanglement measure is rather a non-linear functional of a large set of such observables. Therefore, one typically needs to perform many different measurements, in order to determine the degree of entanglement of a given quantum state. We show, how the entanglement measure concurrence is given in terms of collective observables of two identically prepared quantum states. This allows for a direct experimental estimate of the concurrence of arbitrary finite dimensional quantum states as it is demonstrated in a laboratory experiments with pure twin photon states

  14. An observable entanglement measure

    Energy Technology Data Exchange (ETDEWEB)

    Mintert, Florian [Department of Physics, Harvard University (United Kingdom); Aolita, Leandro [Universidade Federal do Rio de Janeiro (Brazil); Max Planck Institut fuer Physik Komplexer Systeme, Dresden (Germany); Demkowicz Dobrzanski, Rafal; Kus, Marek [Centrum Fizyki Teoretycznej Polskiej Akademii Nauk, Warszawa (Poland); Walborn, Stephen; Souto Ribeiro, Paulo; Davidovich, Luiz [Universidade Federal do Rio de Janeiro (Brazil); Buchleitner, Andreas [Max Planck Institut fuer Physik Komplexer Systeme, Dresden (Germany)

    2007-07-01

    Although entanglement constitutes one of the most remarkable differences between classical and quantum mechanics, and it does have directly observable consequences, it is not an observable like for example momentum or energy. Unlike a regular observable that has an associated hermitean operator, an entanglement measure is rather a non-linear functional of a large set of such observables. Therefore, one typically needs to perform many different measurements, in order to determine the degree of entanglement of a given quantum state. We show, how the entanglement measure concurrence is given in terms of collective observables of two identically prepared quantum states. This allows for a direct experimental estimate of the concurrence of arbitrary finite dimensional quantum states as it is demonstrated in a laboratory experiments with pure twin photon states.

  15. Observation Scheduling System

    Science.gov (United States)

    Chien, Steve A.; Tran, Daniel Q.; Rabideau, Gregg R.; Schaffer, Steven R.

    2011-01-01

    Software has been designed to schedule remote sensing with the Earth Observing One spacecraft. The software attempts to satisfy as many observation requests as possible considering each against spacecraft operation constraints such as data volume, thermal, pointing maneuvers, and others. More complex constraints such as temperature are approximated to enable efficient reasoning while keeping the spacecraft within safe limits. Other constraints are checked using an external software library. For example, an attitude control library is used to determine the feasibility of maneuvering between pairs of observations. This innovation can deal with a wide range of spacecraft constraints and solve large scale scheduling problems like hundreds of observations and thousands of combinations of observation sequences.

  16. Mars Observer's costly solitude

    Science.gov (United States)

    Travis, John

    1993-09-01

    An evaluation is presented of the ramifications of the loss of contact with the Mars Observer spacecraft in August, 1993; the Observer constituted the first NASA mission to Mars in 17 years. It is noted that most, if not all of the scientists involved with the mission will have to find alternative employment within 6 months. The loss of the Observer will leave major questions concerning the geologic history of Mars, and its turbulent atmospheric circulation, unanswered. A detailed account of the discovery of the loss of communications, the unsuccessful steps taken to rectify the problem, and the financial losses incurred through the failure of the mission, are also given.

  17. Observables on Quantum Structures

    CERN Document Server

    Dvurečenskij, Anatolij

    2012-01-01

    An observable on a quantum structure is any $\\sigma$-homomorphism of quantum structures from the Borel $\\sigma$-algebra into the quantum structure. We show that our partial information on an observable known only for all intervals of the form $(-\\infty,t)$ is sufficient to determine uniquely the whole observable defined on quantum structures like $\\sigma$-MV-algebras, $\\sigma$-effect algebras, Boolean $\\sigma$-algebras, monotone $\\sigma$-complete effect algebras with the Riesz Decomposition Property, the effect algebra of effect operators of a Hilbert space, and a system of functions, and an effect-tribe.

  18. IELP Class Observation

    Institute of Scientific and Technical Information of China (English)

    陈了了

    2010-01-01

    @@ As an exchange student majoring in English, I am curious about how English is taught to international students here in America. Therefore, I observed an IELP (Intensive English Learning Program) class in Central Connecticut State University where I study.

  19. Observed Quasar Structure

    Science.gov (United States)

    Schild, Rudolph E.

    2011-05-01

    With the introduction of microlensing (nano-lensing) and reverberation analysis, understanding of the luminous structure surrounding quasars has gone from theoretical speculation to an observer's sport. Micro-lensing with day timescale has demonstrated that quasars have structure on scales of 1 R_G which we attribute to the inner edge of the accretion disc, at central distance 70 R_G in lo-hard state (radio loud) Q0957 quasar, indicated by reverberation. Reverberation of the dominant optical continuum has been detected in all 55 hi-soft quasars with brightness data, originating in the dusty torus observed in UV-optical and IR reverberation. Microlensing simulation compared to brightness monitoring shows that 2/3 of the UV-optical continuum originates in the outer torus. The observed color effects observed in the microlensing support the existence of inner and outer luminous structure.

  20. Mexico - Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Mexican Surface Daily Observations taken at 94 observatories located throughout Mexico, beginning in 1872 and going up through 1981. The data resided on paper...

  1. Motor learning by observing.

    Science.gov (United States)

    Mattar, Andrew A G; Gribble, Paul L

    2005-04-01

    Learning complex motor behaviors like riding a bicycle or swinging a golf club is based on acquiring neural representations of the mechanical requirements of movement (e.g., coordinating muscle forces to control the club). Here we provide evidence that mechanisms matching observation and action facilitate motor learning. Subjects who observed a video depicting another person learning to reach in a novel mechanical environment (imposed by a robot arm) performed better when later tested in the same environment than subjects who observed similar movements but no learning; moreover, subjects who observed learning of a different environment performed worse. We show that this effect is not based on conscious strategies but instead depends on the implicit engagement of neural systems for movement planning and control. PMID:15820701

  2. NWS Corrections to Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Form B-14 is the National Weather Service form entitled 'Notice of Corrections to Weather Records.' The forms are used to make corrections to observations on forms...

  3. Land Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — METAR is the international standard code format for hourly surface weather observations. The acronym roughly translates from French as Aviation Routine Weather...

  4. Oil Rig Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather observations taken at offshore platforms along the United States coastlines. The majority are located in oil-rich areas of the Gulf of Mexico, Gulf of...

  5. Longline Observer Data System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LODS, the Hawaii Longline Observer Data System, is a complete suite of tools designed to collect, process, and manage quality fisheries data and information. Guided...

  6. Simultaneous Marine Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Observations from Naval vessels, primarily American, taken once daily at Greenwich Noon time. Forms are monthly and were captured from records held at the National...

  7. Observing earth from Skylab

    Science.gov (United States)

    1975-01-01

    Skylab technology and observations of earth resources are discussed. Special attention was given to application of Skylab data to mapmaking, geology/geodesy, water resources, oceanography, meteorology, and geography/ecology.

  8. Surface Weather Observing Manuals

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Manuals and instructions for taking weather observations. Includes the annual Weather Bureau 'Instructions for Preparing Meteorological Forms...' and early airways...

  9. Cooperative Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly logs include a daily account of temperature extremes and precipitation, along with snow data at some locations. U.S. Cooperative Observer Program (COOP)...

  10. Connecting Participant Observation Positions

    DEFF Research Database (Denmark)

    McCurdy, Patrick; Uldam, Julie

    2014-01-01

    In this article, we argue for the importance of considering participant observation roles in relation to both insider/outsider and overt/covert roles. Through combining key academic debates on participant observation, which have separately considered insider/outsider and overt/covert participant...... the course of fieldwork and considering the implications of this. To illustrate these dynamics, we draw on two examples from our own ethnographic research experiences in direct action anticapitalist movements....

  11. Deprecating the Observer Pattern

    OpenAIRE

    Maier, Ingo; Rompf, Tiark; Odersky, Martin

    2010-01-01

    Programming interactive systems by means of the observer pattern is hard and error-prone yet is still the implementation standard in many production environments. We present an approach to gradually deprecate observers in favor of reactive programming abstractions. Several library layers help programmers to smoothly migrate existing code from callbacks to a more declarative programming model. Our central high-level API layer embeds an extensible higher-order data-flow DSL into our host langua...

  12. Mars Observer mission

    OpenAIRE

    Albee, A. L.; Arvidson, R.E.; Palluconi, F. D.

    1992-01-01

    The Mars Observer mission will extend the exploration and characterization of Mars by providing new and systematic measurements of the atmosphere, surface, and interior of the planet. These measurements will be made from a low-altitude polar orbiter over a period of 1 Martian year, permitting repetitive observations of the surface and of the seasonal variations of the atmosphere. The mission will be conducted in a manner that will provide new and valuable scientific data using a distributed d...

  13. Solar Prominences: Observations

    Directory of Open Access Journals (Sweden)

    Susanna Parenti

    2014-03-01

    Full Text Available Solar prominences are one of the most common features of the solar atmosphere. They are found in the corona but they are one hundred times cooler and denser than the coronal material, indicating that they are thermally and pressure isolated from the surrounding environment. Because of these properties they appear at the limb as bright features when observed in the optical or the EUV cool lines. On the disk they appear darker than their background, indicating the presence of a plasma absorption process (in this case they are called filaments. Prominence plasma is embedded in a magnetic environment that lies above magnetic inversion lines, denoted a filament channel. This paper aims at providing the reader with the main elements that characterize these peculiar structures, the prominences and their environment, as deduced from observations. The aim is also to point out and discuss open questions on prominence existence, stability and disappearance. The review starts with a general introduction of these features and the instruments used for their observation. Section 2 presents the large scale properties, including filament morphology, thermodynamical parameters, magnetic fields, and the properties of the surrounding coronal cavity, all in stable conditions. Section 3 is dedicated to small-scale observational properties, from both the morphological and dynamical points of view. Section 4 introduces observational aspects during prominence formation, while Section 5 reviews the sources of instability leading to prominence disappearance or eruption. Conclusions and perspectives are given in Section 6.

  14. Observed Barium Emission Rates

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  15. Observation and Quantum Objectivity

    CERN Document Server

    Healey, Richard

    2012-01-01

    The paradox of Wigner's friend challenges the objectivity of description in quantum theory. A pragmatist interpretation can meet this challenge by judicious appeal to decoherence. On this interpretation, quantum theory provides situated agents with resources for predicting and explaining what happens in the physical world---not conscious observations of it. Even in Wigner's friend scenarios, differently situated agents agree on the objective content of statements about the values of physical magnitudes. In more realistic circumstances quantum Darwinism also permits differently situated agents equal observational access to evaluate their truth. In this view, quantum theory has nothing to say about consciousness or conscious experiences of observers. But it does prompt us to reexamine the significance even of everyday claims about the physical world.

  16. Observe Your Shadow

    Science.gov (United States)

    Rovšek, Barbara

    2016-04-01

    Observe Your Shadow was the title of an observational experiment that was, among others, conducted in the scope of the past year's (2014-2015) first Slovene science competition for elementary school pupils between the ages of 6 and 13. The main reason for establishing a new science competition was popularization of science and its experimental methods, particularly among elementary school students. Elementary school teachers are not generally specialists in science, but rather have (and should have) extremely wide scopes of interests and competencies. By providing them with ideas and instructions for science experiments, we aim to enrich regular school lessons. In the first year alone, the competition took place in over half of Slovene elementary schools, with a total of 9000 participating students. In this paper we shall report about pupils' responses to tasks related to one of the experiments, namely, observation of their shadows on a sunny day.

  17. Are Orbitals Observable?

    Directory of Open Access Journals (Sweden)

    Peter Mulder

    2011-07-01

    Full Text Available In this paper I discuss the question whether orbitals can be observed or not. I argue that the answer depends on how the terms 'orbitals' and 'observed' are understood. The fact that different authors take radically different stances on the issue is caused by their employing different uses of either of the two terms. I furthermore discuss a recent argument by Labarca and Lombardi to the effect that the orbital concept in chemistry is discontinuous with that in quantum mechanics. I argue that, quite to the contrary, there is continuity between the two.

  18. Confronting theory with observations

    DEFF Research Database (Denmark)

    Bergström... [], Lars; Bjerrum-Bohr, N. Emil J.; Butt, Sharaz;

    2011-01-01

    This workshop exposed theoretical cosmologists to some of the important observations that are being made of our universe. The goal was to encourage theorists to think concretely about the questions being raised by these new discoveries and also to acquire a sense of the realistic constaints on th...... theoretical ideas and models that will be possible from the coming generation of cosmological observations. The atmosphere was kept lively and informal, with relatively few talks each day, which provided plenty of time for discussion and callaboration among the participants...

  19. Observable Reputation Trading

    OpenAIRE

    Hakenes, Hendrik; Peitz, Martin

    2006-01-01

    Is the reputation of a firm tradable when the change in ownership is observable? We consider a competitive market in which a share of owners must retire in each period. New owners bid for the firms that are for sale. Customers learn the owner’s type, which reflects the quality of the good or service provided, through experience. After observing an ownership change they may want to switch firm. However, in equilibrium, good new owners buy from good old owners and retain high-value customers....

  20. Climate Observations from Space

    Science.gov (United States)

    Briggs, Stephen

    2016-07-01

    The latest Global Climate Observing System (GCOS) Status Report on global climate observations, delivered to the UNFCCC COP21 in November 2016, showed how satellite data are critical for observations relating to climate. Of the 50 Essential Climate Variables (ECVs) identified by GCOS as necessary for understanding climate change, about half are derived only from satellite data while half of the remainder have a significant input from satellites. Hence data from Earth observing satellite systems are now a fundamental requirement for understanding the climate system and for managing the consequences of climate change. Following the Paris Agreement of COP21 this need is only greater. Not only will satellites have to continue to provide data for modelling and predicting climate change but also for a much wider range of actions relating to climate. These include better information on loss and damage, resilience, improved adaptation to change, and on mitigation including information on greenhouse gas emissions. In addition there is an emerging need for indicators of the risks associated with future climate change which need to be better quantified, allowing policy makers both to understand what decisions need to be taken, and to see the consequences of their actions. The presentation will set out some of the ways in which satellite data are important in all aspects of understanding, managing and predicting climate change and how they may be used to support future decisions by those responsible for policy related to managing climate change and its consequences.

  1. Noise storm coordinated observations

    International Nuclear Information System (INIS)

    The usually accepted bipolar model of noise storm centers is irrelevant for the present observations. An alternative model has been proposed in which the different sources of a noise storm center are located in different flux tubes connecting active regions with their surroundings. Radio emission is observed from the wide, descending branch of the flux tubes, opposite to the flaring site. The relation between the sense of circular polarization of the radio emission and the magnetic polarity, has been more precisely defined. The radiation is in the ordinary mode with respect to the underlying large scale photospheric magnetic polarity. Thus the ''irregular'' polarity of noice storm center ''B'' is explained. As regards center ''C'', one should note that although the observed radio emission is polarized in the ordinary mode with respect to the leading spot of region HR 17653, center ''C'' is not situated in flux tubes originating from the leading part of this region according to the proposed model. Rather, the radio sources are located in the wide and descending part of flux tubes connecting a large, quiet area of south magnetic polarity with the following part of the region HR 17653 (of north magnetic polarity). Thus it is the polarity of the extended area which determines the polarization of the radio emission. The observed polarization should result rather from the emission process than from complicated conditions of propagation for the radio waves

  2. Observations of artificial satellites

    Directory of Open Access Journals (Sweden)

    A. MAMMANO

    1964-06-01

    Full Text Available The following publication gives the results of photographic
    observations of artificial satellites made at Asiago during the second
    and third year of this programme. The fixed camera technique and that
    with moving film (the latter still in its experimental stage have been used.

  3. Summary of Observational Techniques

    Czech Academy of Sciences Publication Activity Database

    Koubský, Pavel

    Cambridge: Cambridge University Press, 2012 - (Richards, M.), s. 557-561. (Proceedings of the International Astronomical Union. IAU S282). ISBN 9781107019829. ISSN 1743-9213. [Symposium of the International Astronomical Union /282./. Tatranská Lomnica (SK), 18.07.2011-22.07. 2011] Institutional support: RVO:67985815 Keywords : observational techniques * binary stars Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  4. Extragalactic observational astronomy

    International Nuclear Information System (INIS)

    The lectures on extragalactic observational astronomy includes the redshift controversy, normal galaxies, determination of the Hubble constant using diameters of HII regions, determination of the deceleration parameter, the luminosity--volume test as evidence for the cosmological interpretation of quasars, problems involving clusters and groups of galaxies. (U.S.)

  5. Are Occupation Numbers Observable?

    OpenAIRE

    Furnstahl, R. J.; Hammer, H. -W.

    2001-01-01

    The question of whether occupation numbers and momentum distributions of nucleons in nuclei are observables is considered from an effective field theory perspective. Field redefinitions lead to variations that imply the answer is negative, as illustrated in the interacting Fermi gas at low density. Implications for the interpretation of (e,e'p) experiments with nuclei are discussed.

  6. MAXI observations of GRBs

    CERN Document Server

    Serino, Motoko; Kawai, Nobuyuki; Yoshida, Atsumasa; Ohno, Masanori; Ogawa, Yuji; Nishimura, Yasunori; Fukushima, Kosuke; Higa, Masaya; Ishikawa, Kazuto; Ishikawa, Masaki; Kawamuro, Taiki; Kimura, Masashi; Matsuoka, Masaru; Mihara, Tatehiro; Morii, Mikio; Nakagawa, Yujin E; Nakahira, Satoshi; Nakajima, Motoki; Nakano, Yuki; Negoro, Hitoshi; Onodera, Takuya; Sasaki, Masayuki; Shidatsu, Megumi; Sugimoto, Juri; Sugizaki, Mutsumi; Suwa, Fumitoshi; Suzuki, Kazuhiko; Tachibana, Yutaro; Takagi, Toshihiro; Toizumi, Takahiro; Tomida, Hiroshi; Tsuboi, Yohko; Tsunemi, Hiroshi; Ueda, Yoshihiro; Ueno, Shiro; Usui, Ryuichi; Yamada, Hisaki; Yamamoto, Takayuki; Yamaoka, Kazutaka; Yamauchi, Makoto; Yoshidome, Koshiro; Yoshii, Taketoshi

    2014-01-01

    Monitor of all-sky image (MAXI) Gas Slit Camera (GSC) detects gamma-ray bursts (GRBs) including the bursts with soft spectra, such as X-ray flashes (XRFs). MAXI/GSC is sensitive to the energy range from 2 to 30 keV. This energy range is lower than other currently operating instruments which is capable of detecting GRBs. Since the beginning of the MAXI operation on August 15, 2009, GSC observed 35 GRBs up to the middle of 2013. One third of them are also observed by other satellites. The rest of them show a trend to have soft spectra and low fluxes. Because of the contribution of those XRFs, the MAXI GRB rate is about three times higher than those expected from the BATSE log N - log P distribution. When we compare it to the observational results of the Wide-field X-ray Monitor on the High Energy Transient Explorer 2, which covers the the same energy range to that of MAXI/GSC, we find a possibility that many of MAXI bursts are XRFs with Epeak lower than 20 keV. We discuss the source of soft GRBs observed only b...

  7. Toward observational neutrino astrophysics

    International Nuclear Information System (INIS)

    This paper reviews experimental facilities of solar neutrinos and cosmology. The two experiments were both conceived to search for proton decay. These experiments and theories of particles are briefly reviewed.The first observation of the neutrino burst from the supernova SN 1987A are discussed

  8. Observations of Exoplanet Atmospheres

    CERN Document Server

    Crossfield, Ian J M

    2015-01-01

    Detailed characterization of an extrasolar planet's atmosphere provides the best hope for distinguishing the makeup of its outer layers, and the only hope for understanding the interplay between initial composition, chemistry, dynamics & circulation, and disequilibrium processes. In recent years, some areas have seen rapid progress while developments in others have come more slowly and/or have been hotly contested. This article gives an observer's perspective on the current understanding of extrasolar planet atmospheres prior to the considerable advances expected from the next generation of observing facilities. Atmospheric processes of both transiting and directly-imaged planets are discussed, including molecular and atomic abundances, cloud properties, thermal structure, and planetary energy budgets. In the future we can expect a continuing and accelerating stream of new discoveries, which will fuel the ongoing exoplanet revolution for many years to come.

  9. Observing The Hidden Sector

    CERN Document Server

    Campbell, Bruce A; Maybury, David W

    2008-01-01

    We study the effects of renormalization due to hidden-sector dynamics on observable soft supersymmetry-breaking parameters in the minimal supersymmetric extension of the Standard Model (MSSM), under various hypotheses about their universality at a high input scale. We show that hidden-sector renormalization effects may induce the spurious appearance of unification of the scalar masses at some lower scale, as in mirage unification scenarios. We demonstrate in simple two-parameter models of the hidden-sector dynamics that the parameters may in principle be extracted from experimental measurements, rendering the hidden sector observable. We also discuss the ingredients that would be necessary to carry this programme out in practice.

  10. Permutation properties of observables

    International Nuclear Information System (INIS)

    Relations which characterize the permutation properties of the polarization observables in nuclear reactions are derived. It is shown that the permutation symmetry of the observables in reactions with identical particles in one of the channels is independent of the reaction mechanism. The angular dependence of the vector analyzing power of the reaction d+d→p+t is studied in a model-free manner. It is proved that, contrary to conclusions reached by some authors, the angular-momentum constraints imposed by the direct mechanisms are insufficient for violating the permutation-symmetry properties. It is shown that if the reaction d+d→p+t at a few tens of MeV of energy proceeds via a pure direct mechanism (usually considered as transfer of a nucleon with l = 0) then the character of its vector analyzing power gives evidence for contributions from the l = 2 transitions

  11. Permutation properties of observables

    International Nuclear Information System (INIS)

    Relations are derived which characterize the permutation properties of the polarization observables in nuclear reactions. It is shown that the permutation symmetry of the observables in reactions with identical particles in one of the channels is independent of the reaction mechanism. The angular dependence of the vector analysing power of the reaction d+d→p+t is studied in a model-free manner. It is prooved that contrary to conclusions made by some authors, the angular momentum constrains imposed by the direct mechanism are insufficient for violating the permutation properties. It is shown that if the reaction d+d→p+t at few tens MeV energy proceeds via a pure direct mechanism (usually considered as l=0 nucleon transfer), then the character of its vector analysing power gives evidence for the contribution from l=2 transitions

  12. Observations of space debris

    Science.gov (United States)

    Taff, L. G.

    1991-01-01

    Optical observations of near Earth and deep-space debris conducted at M.I.T.'s artificial satellite observatory will be discussed. A brief review of observing technique, regions of high debris density, and amount of debris in orbit will be given. The unique, duplex facilities of the observatory allow the discrimination of debris from meteors, the construction of an orbital element set, and real-time identification of catalogued artificial satellites. Near-Earth debris is present in large numbers in all the popular near-Earth orbits; at least 5-6 times the 5000-6000 objects in the NORAD catalog. In deep-space, the new presence of Ariane-related debris adds significantly to the existing population which is treble that catalogued by NORAD.

  13. Observation of Gravitational Waves

    Science.gov (United States)

    Gonzalez, Gabriela

    2016-06-01

    On September 14 2015, the two LIGO gravitational wave detectors in Hanford, Washington and Livingston, Louisiana registered a nearly simultaneous signal with time-frequency properties consistent with gravitational-wave emission by the merger of two massive compact objects. Further analysis of the signals by the LIGO Scientific Collaboration and Virgo Collaboration revealed that the gravitational waves detected by LIGO came from the merger of a binary black hole (BBH) system approximately 420 Mpc distant (z=0.09) with constituent masses of 36 and 29 M_sun. I will describe the details of the observation, the status of ground-based interferometric detectors, and prospects for future observations in the new era of gravitational wave astronomy.

  14. Observation of WZ Production

    CERN Document Server

    Abulencia, A; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arguin, J F; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, Yu A; Budd, H S; Budd, S; Budroni, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Bölla, G; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciljak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca-Almenar, C; Cuevas-Maestro, J; Culbertson, R; Cully, J C; Cyr, D; D'Auria, S; D'Onofrio, M; Da Ronco, S; Dagenhart, D; Datta, M; Davies, T; De Barbaro, P; De Cecco, S; De Lentdecker, G; De Pedis, D; Deisher, A; Dell'Orso, Mauro; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; Derwent, P F; Di Giovanni, G P; Di Ruzza, B; Di Turo, P; Dionisi, C; Dittmann, J R; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dorr, C; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernández, J P; Field, R; Flanagan, G; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; García, J E; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimaraes Da Costa, J; Gunay-Unalan, Z; Gómez, G; Gómez-Ceballos, G; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Holloway, A; Hou, S; Houlden, M; Hsu, S C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Höcker, A; Incandela, J; Introzzi, G; Iori, M; Ishizawa, Y; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jensen, H; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kovalev, A; Kraan, A C; Kraus, J; Kravchenko, I; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, S W; Lee, Y J; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P F; Lu, R S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; MacQueen, D; Mack, P; Madrak, R; Maeshima, K; Makhoul, K; Maksimovic, P; Malde, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McCarthy, K; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtälä, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla-Fernández, P A; Mukherjee, A; Mumford, R; Murat, P; Mäki, T; Müller, T; Mülmenstädt, J; Nachtman, J; Nagano, A; Naganoma, J; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, Aldo L; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ranjan, N; Rappoccio, S; Reisert, B; Rekovic, V; Renton, P B; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Sabik, S; Safonov, A; Saint-Denis, R; Sakumoto, W K; Salamanna, G; Salto, O; Saltzberg, D; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shapiro, M D; Shears, T G; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakian, A; Sjölin, J; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suzuki, T; Sánchez, C; Söderberg, M; Taffard, A; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vallecorsa, S; Van Remortel, N; Vanguri, R; Varganov, A; Vataga, E; Velev, G; Veramendi, G; Veszpremi, V; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobuev, I P; Volpi, G; Vázquez, F; Wagner, J; Wagner, P; Wagner, R G; Wagner, R L; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waschke, S; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Würthwein, F; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S; Österberg, K

    2007-01-01

    We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb-1 of integrated luminosity from ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7 +/- 0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to six standard deviations. The measured cross section is sigma(ppbar -> WZ) = 5.0^{+1.8}_{-1.6} pb, consistent with the standard model expectation.

  15. Observations of Exoplanet Atmospheres

    Science.gov (United States)

    Crossfield, Ian J. M.

    2015-10-01

    Detailed characterization of an extrasolar planet's atmosphere provides the best hope for distinguishing the makeup of its outer layers, and the only hope for understanding the interplay between initial composition, chemistry, dynamics and circulation, and disequilibrium processes. In recent years, some areas have seen rapid progress, while developments in others have come more slowly and/or have been hotly contested. This article gives an observer's perspective on the current understanding of extrasolar planet atmospheres prior to the considerable advances expected from the next generation of observing facilities. Atmospheric processes of both transiting and directly imaged planets are discussed, including molecular and atomic abundances, cloud properties, thermal structure, and planetary energy budgets. In the future we can expect a continuing and accelerating stream of new discoveries, which will fuel the ongoing exoplanet revolution for many years to come.

  16. Awareness as observational heterarchy

    Directory of Open Access Journals (Sweden)

    Kohei eSonoda

    2013-10-01

    Full Text Available Libet et al. (1983 revealed that brain activity precedes conscious intention. For convenience in this study, we divide brain activity into two parts: a conscious field (CF and an unconscious field (UF. Most studies have assumed a comparator mechanism or an illusion of CF and discuss the difference of prediction and postdiction. We propose that problems to be discussed here are a twisted sense of agency between CF and UF, and another definitions of prediction and postdiction in a mediation process for the twist. This study specifically examines the definitions throughout an observational heterarchy model based on internal measurement. The nature of agency must be emergence that involves observational heterarchy. Consequently, awareness involves processes having duality in the sense that it is always open to the world (postdiction and that it also maintains self robustly (prediction.

  17. Photon position observable

    OpenAIRE

    Hawton, Margaret; Debierre, Vincent

    2015-01-01

    In biorthogonal quantum mechanics, the eigenvectors of a nonhermitian operator and those of its adjoint are biorthogonal and complete and the probability for a transition from a quantum state to one of these eigenvectors is positive definite. We apply this formalism to the long standing problem of the position observable in quantum electrodynamics. The nonhermitian operators are generalized Newton-Wigner position operators whose eigenvectors are the quantum field and its canonically conjugate...

  18. Multicolour Observations, Inhomogeneity & Evolution

    OpenAIRE

    Hellaby, Charles

    2000-01-01

    We propose a method of testing source evolution theories that is independent of the effects of inhomogeneity, and thus complementary to other studies of evolution. It is suitable for large scale sky surveys, and the new generation of large telescopes. In an earlier paper it was shown that basic cosmological observations - luminosity versus redshift, area distance versus redshift and number counts versus redshift - cannot separate the effects of cosmic inhomogeneity, cosmic evolution and sourc...

  19. Observability and Optimality

    OpenAIRE

    1989-01-01

    Observability of an individual's excess demand function for assets and commodities as all prices and revenue vary suffices in order to recover his von Neumann-Morgenstern utility function. This is generically the case, even when the asset market is incomplete and the cardinal utility indices state dependent, as long as there are at least two commodities traded in spot markets at each state of nature. On the contrary, if the response of individuals' excess demand for assets as prices in spot c...

  20. Minisuperspaces: Observables and Quantization

    OpenAIRE

    Ashtekar, Abhay; Tate, Ranjeet S.; Uggla, Claes

    1993-01-01

    A canonical transformation is performed on the phase space of a number of homogeneous cosmologies to simplify the form of the scalar (or, Hamiltonian) constraint. Using the new canonical coordinates, it is then easy to obtain explicit expressions of Dirac observables, i.e.\\ phase space functions which commute weakly with the constraint. This, in turn, enables us to carry out a general quantization program to completion. We are also able to address the issue of time through ``deparametrization...

  1. Heisenberg's observability principle

    OpenAIRE

    Wolff, JE

    2014-01-01

    Werner Heisenberg's 1925 paper ‘Quantum-theoretical re-interpretation of kinematic and mechanical relations’ marks the beginning of quantum mechanics. Heisenberg famously claims that the paper is based on the idea that the new quantum mechanics should be ‘founded exclusively upon relationships between quantities which in principle are observable’. My paper is an attempt to understand this observability principle, and to see whether its employment is philosophically defensible. Against interpr...

  2. Observation and Quantum Objectivity

    OpenAIRE

    Healey, Richard

    2012-01-01

    The paradox of Wigner's friend challenges the objectivity of description in quantum theory. A pragmatist interpretation can meet this challenge by judicious appeal to decoherence. On this interpretation, quantum theory provides situated agents with resources for predicting and explaining what happens in the physical world---not conscious observations of it. Even in Wigner's friend scenarios, differently situated agents agree on the objective content of statements about the values of physical ...

  3. Enhanced ocean observational capability

    Energy Technology Data Exchange (ETDEWEB)

    Volpe, A M; Esser, B K

    2000-01-10

    Coastal oceans are vital to world health and sustenance. Technology that enables new observations has always been the driver of discovery in ocean sciences. In this context, we describe the first at sea deployment and operation of an inductively coupled plasma mass spectrometer (ICPMS) for continuous measurement of trace elements in seawater. The purpose of these experiments was to demonstrate that an ICPMS could be operated in a corrosive and high vibration environment with no degradation in performance. Significant advances occurred this past year due to ship time provided by Scripps Institution of Oceanography (UCSD), as well as that funded through this project. Evaluation at sea involved performance testing and characterization of several real-time seawater analysis modes. We show that mass spectrometers can rapidly, precisely and accurately determine ultratrace metal concentrations in seawater, thus allowing high-resolution mapping of large areas of surface seawater. This analytical capability represents a significant advance toward real-time observation and understanding of water mass chemistry in dynamic coastal environments. In addition, a joint LLNL-SIO workshop was convened to define and design new technologies for ocean observation. Finally, collaborative efforts were initiated with atmospheric scientists at LLNL to identify realistic coastal ocean and river simulation models to support real-time analysis and modeling of hazardous material releases in coastal waterways.

  4. NICER observation of magnetars

    Science.gov (United States)

    Enoto, Teruaki; Kaspi, Victoria M.; Arzoumanian, Zaven

    2016-04-01

    The Neutron Star Interior Composition ExploreR (NICER) is a NASA Explorer Misson of Opportunity as an attached payload aboard the International Space Station (ISS), launch in August 2016. The NICER is planned to study the interior composition and structure within neutron stars via high precise measurement of their stellar mass and radius, also to investigate dynamic and energetic behaviors of their activities. This mission will enable pulsar rotation-resolved spectroscopy in the 0.2--12 keV energy band with large collection area (about twice of the XMM-Newton observatory for soft X-ray timing), precise time-tagging resolution (~200 nsec, 25 times better than RXTE), and high sensitivity (about 2e-14 erg/s/cm2 in the 0.5--10 keV, 5-sigma for 10 ksec exposure). As one of prime goals of the mission, we will describe the science planning of the NICER magnetar observations. The NICER is expected to provide monitoring of fainter magnetar sources which cannot be performed by Swift due to its little collective area. Deep observations of quiescent magnetars and high-B radio pulsars can be also performed with the NICER to study their spectral similarity as a key to investigate the connection between these two sub-classes. Finally, ToO programs are suitable to follow-up the magnate outburst relaxation down to much fainter flux level. We will introduce the NICER strategy of the magnetar observation.

  5. HF Doppler observations

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T.; Sugiuchi, H.; Ishimine, T.; Maeno, H.; Honma, S.

    1986-12-01

    This paper reports the solar flare and geomagnetic storm effects on the frequency of JJY signals received at Okinawa (f = 15 MHz) and Kokubunji (f = 5 and 8 MHz) during the period of June-September 1982. The increase in the electron density due to solar flares is deduced from the Doppler frequency deviation of 1 Hz as 2 x 10/sup 15/ electrons/m/sub 2/ below the reflection height. The result is in good agreement with the observation of the total electron content by the Faraday rotation measurements. On July 13, 1982, an abrupt increase of 0.8 Hz in frequency followed by a decrease of 0.6 Hz was observed in association with the huge storm sudden commencement. This fact indicates a successive transmission of westward electric field of 1.5 mV/m and eastward electric field of 1.1 mV/m from the outer magnetosphere to the low latitude ionosphere. It is shown that the decreases in Doppler frequency were associated with geomagnetic bays. The strength of the electric field (1.8 mV/m) derived from the Doppler frequency deviation is 20% of that of the electric field which is required to produce ionospheric electric currents responsible for the geomagnetic field variation on the ground. The large amplitude Doppler frequency oscillations of period of 1-1.5 h were observed at Kokubunji and Okinawa with a delay time of 20-25 min during the geomagnetic storm on September 6, 1982. It is suggested that the large-scale TID (Travelling Ionospheric Disturbance) with a phase velocity of 600 m/s and a wavelength of 2000 km is produced at high latitudes and is propagated to low latitudes.

  6. Pion observables and QCD

    International Nuclear Information System (INIS)

    The Dyson-Schwinger equations (DSEs) are a tower of coupled integral equations that relate the Green functions of QCD to one another. Solving these equations provides the solution of QCD. This tower of equations includes the equation for the quark self-energy, which is the analogue of the gap equation in superconductivity, and the Bethe-Salpeter equation, the solution of which is the quark-antiquark bound state amplitude in QCD. The application of this approach to solving Abelian and non-Abelian gauge theories is reviewed. The nonperturbative DSE approach is being developed as both: (1) a computationally less intensive alternative and; (2) a complement to numerical simulations of the lattice action of QCD. In recent years, significant progress has been made with the DSE approach so that it is now possible to make sensible and direct comparisons between quantities calculated using this approach and the results of numerical simulations of Abelian gauge theories. Herein the application of the DSE approach to the calculation of pion observables is described: the π-π scattering lengths (a00, a02, A11, a22) and associated partial wave amplitudes; the π0 → γγ decay width; and the charged pion form factor, Fπ(q2). Since this approach provides a straightforward, microscopic description of dynamical chiral symmetry breaking (DXSB) and confinement, the calculation of pion observables is a simple and elegant illustrative example of its power and efficacy. The relevant DSEs are discussed in the calculation of pion observables and concluding remarks are presented

  7. Distributed Observer Network

    Science.gov (United States)

    Conroy, Michael; Mazzone, Rebecca; Little, William; Elfrey, Priscilla; Mann, David; Mabie, Kevin; Cuddy, Thomas; Loundermon, Mario; Spiker, Stephen; McArthur, Frank; Srey, Tate; Bonilla, Dennis

    2010-01-01

    The Distributed Observer network (DON) is a NASA-collaborative environment that leverages game technology to bring three-dimensional simulations to conventional desktop and laptop computers in order to allow teams of engineers working on design and operations, either individually or in groups, to view and collaborate on 3D representations of data generated by authoritative tools such as Delmia Envision, Pro/Engineer, or Maya. The DON takes models and telemetry from these sources and, using commercial game engine technology, displays the simulation results in a 3D visual environment. DON has been designed to enhance accessibility and user ability to observe and analyze visual simulations in real time. A variety of NASA mission segment simulations [Synergistic Engineering Environment (SEE) data, NASA Enterprise Visualization Analysis (NEVA) ground processing simulations, the DSS simulation for lunar operations, and the Johnson Space Center (JSC) TRICK tool for guidance, navigation, and control analysis] were experimented with. Desired functionalities, [i.e. Tivo-like functions, the capability to communicate textually or via Voice-over-Internet Protocol (VoIP) among team members, and the ability to write and save notes to be accessed later] were targeted. The resulting DON application was slated for early 2008 release to support simulation use for the Constellation Program and its teams. Those using the DON connect through a client that runs on their PC or Mac. This enables them to observe and analyze the simulation data as their schedule allows, and to review it as frequently as desired. DON team members can move freely within the virtual world. Preset camera points can be established, enabling team members to jump to specific views. This improves opportunities for shared analysis of options, design reviews, tests, operations, training, and evaluations, and improves prospects for verification of requirements, issues, and approaches among dispersed teams.

  8. Geomagnetic Observations and Models

    CERN Document Server

    Mandea, Mioara

    2011-01-01

    This volume provides comprehensive and authoritative coverage of all the main areas linked to geomagnetic field observation, from instrumentation to methodology, on ground or near-Earth. Efforts are also focused on a 21st century e-Science approach to open access to all geomagnetic data, but also to the data preservation, data discovery, data rescue, and capacity building. Finally, modeling magnetic fields with different internal origins, with their variation in space and time, is an attempt to draw together into one place the traditional work in producing models as IGRF or describing the magn

  9. Observing GRBs with TMT

    CERN Document Server

    Crampton, David; 10.1393/ncb/i2007-10274-1

    2008-01-01

    The Thirty-Meter Telescope is an ambitious project to build a giant segmented mirror telescope with fully integrated adaptive optics systems that will produce diffraction-limited images. A powerful suite of instruments is being developed that, coupled with the ability to rapidly switch between targets and instruments, will allow TMT to take advantage of GRBs to probe fundamental physics in extreme conditions and as the ultimate tomographic beacons, especially if some are as far as z ~ 10. This article gives a brief summary of TMT and its instruments, and some examples of the potential offered by observation of GRBs.

  10. observations with DEFPOS

    Science.gov (United States)

    Sahan, M.

    2011-02-01

    A 7.5 cm, dual étalon Fabry-Pérot spectrometer called DEFPOS has been set up at Coudé focus of 150 cm RTT150 telescope at TUBITAK National Observatory (TUG, Antalya, Turkey) to investigate the physical properties of Diffuse Ionized Gas (DIG) in our Galaxy. The spectrometer, having a 4 arcmin circular field of view over a 200 km s-1 (4.4 Å) spectral window near Hα, has been used to observe H II regions and Planetary Nebulae (PNe) since May 2007 (Sahan et al. 2009). Early observations have been analyzed and physical and kinematic properties such as the intensity, the line width, and the LSR velocity are presented here. These values are compared with earlier results from different studies. In this study, I discuss some results obtained by DEFPOS, including two H II regions (Sh2-156, Sh2-157), and two PNe (NGC 1360, and NGC 6826). The Intensities, the radial velocities and the line widths of the Hα emission line vary from 101.4R to 149.97R (1 Rayleigh =106/4π photons cm-2 sr-1 s-1 = 2.41×10-7 erg cm-2 s-1 sr-1 at Hα), -41.19 km s-1 to +8.34 km s-1, and 39.55 km s-1 to 58.23 km s-1, respectively.

  11. Stereoscopically Observing Manipulative Actions.

    Science.gov (United States)

    Ferri, S; Pauwels, K; Rizzolatti, G; Orban, G A

    2016-08-01

    The purpose of this study was to investigate the contribution of stereopsis to the processing of observed manipulative actions. To this end, we first combined the factors "stimulus type" (action, static control, and dynamic control), "stereopsis" (present, absent) and "viewpoint" (frontal, lateral) into a single design. Four sites in premotor, retro-insular (2) and parietal cortex operated specifically when actions were viewed stereoscopically and frontally. A second experiment clarified that the stereo-action-specific regions were driven by actions moving out of the frontoparallel plane, an effect amplified by frontal viewing in premotor cortex. Analysis of single voxels and their discriminatory power showed that the representation of action in the stereo-action-specific areas was more accurate when stereopsis was active. Further analyses showed that the 4 stereo-action-specific sites form a closed network converging onto the premotor node, which connects to parietal and occipitotemporal regions outside the network. Several of the specific sites are known to process vestibular signals, suggesting that the network combines observed actions in peripersonal space with gravitational signals. These findings have wider implications for the function of premotor cortex and the role of stereopsis in human behavior. PMID:27252350

  12. Global observations of formaldehyde

    Science.gov (United States)

    Wittrock, F.; Richter, A.; Heckel, A.; Tarsu, M.; Burrows, J. P.

    Formaldehyde (HCHO) indicates and supports photochemical activity in the atmosphere. Large amounts are expected to found in industrial areas and during biomass burning. HCHO is a major intermediate in the degradation of methane (and many other hydrocarbons). In the absence of heterogenous losses, essentially every methane molecule is converted to HCHO. Therefore it is found throughout the troposphere. It is destroyed via photolysis and reaction with OH. In continental boundary layers, non-methane hydrocarbons (NMHCs) emitted by biogenic and anthropogenic sources dominate over Methane also as a source of HCHO. GOME is the first instrument, that allows observations of Formaldehyde on a global scale giving the opportunity to improve our knowledge about emission fluxes of Methane and NMHCs. This study presents GOME observations of formaldehyde since launch of ERS-2 in 1995. Ground-based measurements are used to validate the GOME HCHO product. In addition time series for selected regions are shown to illustrate the general interannual and interseasonal variation of HCHO depending on the main sources.

  13. Global observations from PHOBOS

    Science.gov (United States)

    Phobos Collaboration; Baker, Mark D.; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Bal, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwon, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kan, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stodulski, G. S. T. M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2003-03-01

    Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies. Three empirical observations have emerged from this dataset which require theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central Au+Au collisions, when expressed as $dN/d\\eta'$ ($\\eta' \\equiv \\eta-y_{beam}$), becomes energy independent at high energy for a broad region of $\\eta'$ around $\\eta'=0$. This energy-independent region grows with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity between particle production in e+e- and Au+Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles and the longitudinal distribution of produced particles are approximately the same in e+e- and in scaled Au+Au. This observation was not predicted and has not been explained. Finally, particle production has been found to scale approximately with the number of participating nucleon pairs for $N_{part}>65$. This scaling occurs both for the total multiplicity and for high $\\pT$ particles (3 $<\\pT<$ 4.5 GeV/c).

  14. Spatial Standard Observer

    Science.gov (United States)

    Watson, Andrew B. (Inventor)

    2012-01-01

    The present invention relates to devices and methods for the measurement and/or for the specification of the perceptual intensity of a visual image, or the perceptual distance between a pair of images. Grayscale test and reference images are processed to produce test and reference luminance images. A luminance filter function is convolved with the reference luminance image to produce a local mean luminance reference image. Test and reference contrast images are produced from the local mean luminance reference image and the test and reference luminance images respectively, followed by application of a contrast sensitivity filter. The resulting images are combined according to mathematical prescriptions to produce a Just Noticeable Difference, JND value, indicative of a Spatial Standard Observer, SSO. Some embodiments include masking functions, window functions, special treatment for images lying on or near borders and pre-processing of test images.

  15. Transverse gravity versus observations

    International Nuclear Information System (INIS)

    Theories of gravity invariant under those diffeomorphisms generated by transverse vectors, ∂μξμ = 0 are considered. Such theories are dubbed transverse, and differ from General Relativity in that the determinant of the metric, g, is a transverse scalar. We comment on diverse ways in which these models can be constrained using a variety of observations. Generically, an additional scalar degree of freedom mediates the interaction, so the usual constraints on scalar-tensor theories have to be imposed. If the purely gravitational part is Einstein-Hilbert but the matter action is transverse, the models predict that the three a priori different concepts of mass (gravitational active and gravitational passive as well as inertial) are not equivalent anymore. These transverse deviations from General Relativity are therefore tightly constrained, actually correlated with existing bounds on violations of the equivalence principle, local violations of Newton's third law and/or violation of Local Position Invariance

  16. Observations of Protostellar Disks

    Science.gov (United States)

    Ménard, F.

    2004-12-01

    Accretion disks are pivotal elements in the formation and early evolution of solar-like stars. On top of supplying the raw material, their internal conditions also regulate the formation of planets. Their study therefore holds the key to solve the mystery of the formation of our Solar System. This chapter focuses on observational studies of circumstellar disks associated with pre-main sequence solar-like stars. The direct measurement of disk parameters poses an obvious challenge: at the distance of typical star forming regions (e.g., ˜140pc for Taurus), a planetary system like ours (with diameter ≃ 50AU out to Pluto, but excluding the Kuiper belt) subtends only 0.35". Yet its surface brightness is low in comparison to the bright central star and high angular and high contrast imaging techniques are required if one hopes to resolve and measure these protoplanetary disks. Fortunately, capable instruments providing 0.1" resolution or better and high contrast have been available for just about 10 years now. They are covering a large part of the electromagnetic spectrum, from the UV/Optical with HST and the near-infrared from ground-based adaptive optics systems, to the millimetric range with long-baseline radio interferometers. It is therefore not surprising that our knowledge of the structure of the disks surrounding low-mass stars has made a gigantic leap forward in the last decade. In the following pages I will attempt to give an overview of the structural and physical parameters of protoplanetary disks that can be estimated today from direct observations.

  17. Quadrature, Interpolation and Observability

    Science.gov (United States)

    Hodges, Lucille McDaniel

    1997-01-01

    Methods of interpolation and quadrature have been used for over 300 years. Improvements in the techniques have been made by many, most notably by Gauss, whose technique applied to polynomials is referred to as Gaussian Quadrature. Stieltjes extended Gauss's method to certain non-polynomial functions as early as 1884. Conditions that guarantee the existence of quadrature formulas for certain collections of functions were studied by Tchebycheff, and his work was extended by others. Today, a class of functions which satisfies these conditions is called a Tchebycheff System. This thesis contains the definition of a Tchebycheff System, along with the theorems, proofs, and definitions necessary to guarantee the existence of quadrature formulas for such systems. Solutions of discretely observable linear control systems are of particular interest, and observability with respect to a given output function is defined. The output function is written as a linear combination of a collection of orthonormal functions. Orthonormal functions are defined, and their properties are discussed. The technique for evaluating the coefficients in the output function involves evaluating the definite integral of functions which can be shown to form a Tchebycheff system. Therefore, quadrature formulas for these integrals exist, and in many cases are known. The technique given is useful in cases where the method of direct calculation is unstable. The condition number of a matrix is defined and shown to be an indication of the the degree to which perturbations in data affect the accuracy of the solution. In special cases, the number of data points required for direct calculation is the same as the number required by the method presented in this thesis. But the method is shown to require more data points in other cases. A lower bound for the number of data points required is given.

  18. Forest Fire Observation

    Science.gov (United States)

    1982-01-01

    Conditions on the perimeter of a forest fire can be obtained by use of airborne remote sensing techniques demonstrated by Ames Research Center. An Ames U-2 high-altitude survey aircraft served as an aerial fire observation system. Equipped with two types of sensors, the U-2 produces real-time infrared images of fireground scenes. Information acquired by the U-2's scanners defines the fire boundary and aids fire management decisions by showing the size, shape and direction of burn and the locations of hot spots in the fire zone. U-2 sends sensor date in digital form to an antenna at Ames Research Center. There the data is computer processed into images which are overlaid on U.S. Geological Survey topographical maps of the fire area. Maps are then transmitted by telecopy machine directly to fire control center. Whole process takes less than 10 minutes and the U-2 can provide information for up to five hours. Ames antenna can pick up signals from the U-2 anywhere within a 300 mile radius from Ames.

  19. The constellation observing Atlas

    CERN Document Server

    Privett, Grant

    2013-01-01

    Designed for anyone who wishes to learn the constellations or observe the best and brightest deep sky objects and double stars, this book contains an alphabetical list of constellations complete with star maps, historical background, and highlights of deep sky objects. Each entry contains position and physical information on enough stars to support astronomers in star-hopping, swinging the telescope from star to star to star to arrive at a faint target. It provides a carefully selected list of accessible and rewarding deep sky objects. Full-color maps show the constellations, with star types (spectral and physical) indicated by the colors used on the map. Extended objects such as galaxies and nebulae are shown with the approximate apparent size in the sky. With unmatched thoroughness and accessibility, this is a constellation atlas that makes the ideal companion to a night's telescope viewing, for novices and expert amateur astronomers alike. Easy to navigate and refer to, it is the key that unlocks the do...

  20. AGN Observations with STACEE

    Science.gov (United States)

    Bramel, D. A.; Boone, L. M.; Carson, J.; Chae, E.; Covault, C. E.; Fortin, P.; Gingrich, D. M.; Hanna, D. S.; Hinton, J. A.; Mukherjee, R.; Mueller, C.; Ong, R. A.; Ragan, K.; Scalzo, R. A.; Schuette, D. R.; Theoret, C. G.; Williams, D. A.; Wong, J.; Zweerink, J.

    2003-03-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a gamma-ray detector designed to study astrophysical sources at energies between 50 and 500 GeV. It uses 64 large, steerable mirrors at the National Solar Tower Test Facility near Albuquerque, NM, USA to collect Cherenkov light from extended air showers and concentrate it onto an array of photomultiplier tubes. The large light-collection area gives it a lower energy threshold than imaging-type Cherenkov detectors. STACEE is now fully operational, and we report here on the performance of the complete STACEE instrument, as well as preliminary results of recent observations of several AGN targets. This work was supported in part by the National Science Foundation (under Grant Numbers PHY-9983836, PHY-0070927, and PHY-0070953), the Natural Sciences and Engineering Research Council, Le Fond Quebecois de la Recherche sur la Nature et les Technologies (FQRNT), the Research Corporation, and the California Space Institute. CEC is a Cottrell Scholar of the Research Corporation.

  1. CMS tracker observes muons

    CERN Multimedia

    2006-01-01

    A computer image of a cosmic ray traversing the many layers of the TEC+ silicon sensors. The first cosmic muon tracks have been observed in one of the CMS tracker endcaps. On 14 March, a sector on one of the two large tracker endcaps underwent a cosmic muon run. Since then, thousands of tracks have been recorded. These data will be used not only to study the tracking, but also to exercise various track alignment algorithms The endcap tested, called the TEC+, is under construction at RWTH Aachen in Germany. The endcaps have a modular design, with silicon strip modules mounted onto wedge-shaped carbon fibre support plates, so-called petals. Up to 28 modules are arranged in radial rings on both sides of these plates. One eighth of an endcap is populated with 18 petals and called a sector. The next major step is a test of the first sector at CMS operating conditions, with the silicon modules at a temperature below -10°C. Afterwards, the remaining seven sectors have to be integrated. In autumn 2006, TEC+ wil...

  2. Effect of the IMF By component on the ionospheric flow overhead at EISCAT: observations and theory

    Directory of Open Access Journals (Sweden)

    S. W. H. Cowley

    Full Text Available We have analysed a database of ∼300 h of tristatic ionospheric velocity measurements obtained overhead at Tromsø (66.3° magnetic latitude by the EISCAT UHF radar system, for the presence of flow effects associated with the y-component of the IMF. Since it is already known that the flow depends upon IMF Bz, a least-squares multivariate analysis has been used to determine the flow dependence on both IMF By and Bz simultaneously. It is found that significant flow variations with IMF By occur, predominantly in the midnight sector (∼2100–0300 MLT, but also pre-dusk (∼1600–1700 MLT, which are directed eastward for IMF By positive and westward for IMF By negative. The flows are of magnitude 20–30 m s–1 nT–1 in the midnight sector, and smaller, 10–20 m s–1 nT–1, pre-dusk, and are thus associated with significant changes of flow of order a few hundred m s–1 over the usual range of IMF By of about ±5 nT. At other local times the IMF By-related perturbation flows are much smaller, less than ∼5 m s–1 nT–1, and consistent with zero within the uncertainty estimates. We have investigated whether these IMF By-dependent flows can be accounted for quantitatively by a theoretical model in which the equatorial flow in the inner magnetosphere is independent of IMF By, but where distortions of the magnetospheric magnetic field associated with a "penetrating" component of the IMF By field changes the mapping of the field to the ionosphere, and hence the ionospheric flow. We find that the principal flow perturbation produced by this effect is an east-west flow whose sense is determined by the north-south component of the unperturbed flow. Perturbations in the north-south flow are typically smaller by more than an order of magnitude, and generally negligible in terms of observations. Using equatorial flows which are determined from EISCAT data for zero IMF By, to which the corotation flow has been added, the theory predicts the presence

  3. Effect of the IMF By component on the ionospheric flow overhead at EISCAT: observations and theory

    OpenAIRE

    Khan, H.; Cowley, S. W. H.

    2000-01-01

    We have analysed a database of ∼300 h of tristatic ionospheric velocity measurements obtained overhead at Tromsø (66.3° magnetic latitude) by the EISCAT UHF radar system, for the presence of flow effects associated with the y-component of the IMF. Since it is already known that the flow depends upon IMF Bz, a least-squares multivariate analysis has been used to determine the flow dependence on both IMF By and Bz simultaneously. It is found that significant flow va...

  4. Rule (4) and Continuous Observation

    CERN Document Server

    Mould, R A

    2003-01-01

    The effect of rule (4) on a series or parallel sequence of quantum mechanical steps is to insure that a conscious observer does not skip a step. This rule effectively places the observer in continuous contact with the system. Key Words: brain states, continuous observation, conscious observer, measurement, probability current, state reduction, wave collapse.

  5. Sliding mode observers and observability singularity in chaotic synchronization

    OpenAIRE

    L. Boutat-Baddas; J. P. Barbot; Boutat, D.; R. Tauleigne

    2004-01-01

    We present a new secured data transmission based on a chaotic synchronization and observability singularity. For this, we adopt an approach based on an inclusion of the message in the system structure and we use a sliding mode observer for system with unknown input in order to recover the information. We end the paper with an example of chaotic system with an observability bifurcation. Moreover, this example highlights some benefits of the so-called step-by-step sliding mode observer.

  6. OBPRELIM Observer Preliminary Data System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Paper logs are the primary data collection tool used by observers of the Northeast Fisheries Observer Program and Industry Funded Scallop Program deployed on...

  7. Ship Observations - VOS and Navy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Combination of Voluntary Observing Ship (VOS) and US Navy Ship weather observations. Obs generally taken 2-4 times daily at 00, 06, 12, and 18z.

  8. US Naval Observatory Hourly Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly observations journal from the National Observatory in Washington DC. The observatory is the first station in the United States to produce hourly observations...

  9. Tev Blazars: Status of Observations

    OpenAIRE

    Krennrich, F.; Biller, S. D.; Bond, I. H.; Boyle, P. J.; Bradbury, S. M.; Breslin, A. C.; J. H. Buckley(Department of Physics, Washington University, St. Louis, USA); Burdett, A. M.; Bussons-Gordo, J.; Carter-Lewis, D. A.; Catanese, M.; Cawley, M. F.; Fegan, D. J.; Finley, J. P.; Gaidos, J. A.

    1998-01-01

    The close relation between ground-based TeV observations and satellite borne $\\gamma$-ray measurements has been important for the understanding of blazars. The observations which involve the TeV component in blazar studies are reviewed.

  10. Polarimetric observations of GRB 011211

    OpenAIRE

    S. Covino(INAF - Oss. Astronomico di Brera); Lazzati, D.; Malesani, D.; Ghisellini, G.; Israel, G. L.; Stella, L.; Cimatti, A.; Di Serego, S.; Fiore, F.; Kawai, N.; S. Ortolani; Pasquini, L.; Ricker, G.; P. Saracco(INFN, Sezione di Genova); Tagliaferri, G.

    2002-01-01

    We present and discuss polarimetric observations performed with the VLT-UT3 (Melipal) on the afterglow of GRB 011211, ~35 hours after the burst onset. The observations yielded a 3-sigma upper limit of P

  11. Central American and Caribbean Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather and soil temperature observations from foreign countries, taken by foreign and American observers. Includes NOAA forms collected and archived at NCDC, and...

  12. US Air Force Base Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly observations taken by U.S. Air Force personnel at bases in the United States and around the world. Foreign observations concentrated in the Middle East and...

  13. Skylab observations of Comet Kohoutek

    Science.gov (United States)

    Snoddy, W. C.; Gary, G. A.

    1974-01-01

    This paper summarizes the special operational procedures developed to observe the Comet Kohoutek from Skylab and the scientific results from these observations. Emphasis is placed on results from Skylab experiments S052, White Light Coronagraph; S201, Far UV Electronographic Camera; S233, Kohoutek Photometric Photography; S019, UV Stellar Astronomy; S183, Ultraviolet Panorama Telescope; and S082B, Ultraviolet Spectrography. Visual observations by the astronaut crew and the significance of these observations are discussed.

  14. Historical Sunspot Observations: A Review

    OpenAIRE

    J. M. Vaquero

    2007-01-01

    Early observations of sunspot were realised by the naked eye. Possible utilization of these records for studying the long-term change in the Sun is discussed here. Other historical sunspot observations with camera obscuras are also discussed. Moreover, the best record of the behaviour of the Sun exists for the last four centuries thanks to the observations of sunspots with telescope. These observations should allow us to know the number, position, and area of sunspots as well as some relevant...

  15. Observations

    DEFF Research Database (Denmark)

    Rossiter, John R.; Percy, Larry

    2013-01-01

    product or service or to achieve a higher price that consumers are willing to pay than would obtain in the absence of advertising. What has changed in recent years is the notable worsening of the academic-practitioner divide, which has seen academic advertising researchers pursuing increasingly......This article is a commentary on the theme of the 2012 ICORIA Conference held in Stockholm, which was about 'the changing role of advertising'. We propose that the role of advertising has not changed. the role of advertising has always been, and will continue to be, to sell more of the branded...... requiring a new model of how advertising communicates and persuades, which, as the authors' textbooks explain, is sheer nonsense and contrary to the goal of integrated marketing. We provide in this article a translation of practitioners' jargon into more scientifically acceptable terminology as well as a...

  16. Fault detection using (PI) observers

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, J.; Shafai, B.

    The fault detection and isolation (FDI) problem in connection with Proportional Integral (PI) Observers is considered in this paper. A compact formulation of the FDI design problem using PI observers is given. An analysis of the FDI design problem is derived with respectt to the time domain...... properties. A method for design of PI observers applied to FDI is given....

  17. Sliding mode observers and observability singularity in chaotic synchronization

    Directory of Open Access Journals (Sweden)

    Boutat-Baddas L.

    2004-01-01

    Full Text Available We present a new secured data transmission based on a chaotic synchronization and observability singularity. For this, we adopt an approach based on an inclusion of the message in the system structure and we use a sliding mode observer for system with unknown input in order to recover the information. We end the paper with an example of chaotic system with an observability bifurcation. Moreover, this example highlights some benefits of the so-called step-by-step sliding mode observer.

  18. VERITAS Observations under Bright Moonlight

    CERN Document Server

    ,

    2015-01-01

    The presence of moonlight is usually a limiting factor for imaging atmospheric Cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes (PMTs). In their standard configuration, the extra noise limits the sensitivity of the experiment to gamma-ray signals and the higher PMT currents also accelerates PMT aging. Since fall 2012, observations have been carried out with VERITAS under bright moonlight (Moon illumination $> 35\\%$), in two observing modes, by reducing the voltage applied to the PMTs and with UV bandpass filters, which allow observations up to $\\sim80\\%$ Moon illumination resulting in $29\\%$ more observing time over the course of the year. In this presentation, we provide details of these new observing modes and their performance relative to the standard VERITAS observations.

  19. NS&T MANAGEMENT OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Gianotto, David

    2014-06-01

    The INL Management Observation Program (MOP) is designed to improve managers and supervisors understanding of work being performed by employees and the barriers impacting their success. The MOP also increases workers understanding of managements’ expectations as they relate to safety, security, quality, and work performance. Management observations (observations) are designed to improve the relationship and trust between employees and managers through increased engagement and interactions between managers and researchers in the field. As part of continuous improvement, NS&T management took initiative to focus on the participation and quality of observations in FY 14. This quarterly report is intended to (a) summarize the participation and quality of management’s observations, (b) assess observations for commonalities or trends related to facility or process barriers impacting research, and (c) provide feedback and make recommendations for improvements NS&T’s MOP.

  20. NS&T Management Observations

    Energy Technology Data Exchange (ETDEWEB)

    Gianotto, David [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2014-09-01

    The INL Management Observation Program (MOP) is designed to improve managers and supervisors understanding of work being performed by employees and the barriers impacting their success. The MOP also increases workers understanding of managements’ expectations as they relate to safety, security, quality, and work performance. Management observations (observations) are designed to improve the relationship and trust between employees and managers through increased engagement and interactions between managers and researchers in the field. As part of continuous improvement, NS&T management took initiative to focus on the participation and quality of observations in FY 14. This quarterly report is intended to (a) summarize the participation and quality of management’s observations, (b) assess observations for commonalities or trends related to facility or process barriers impacting research, and (c) provide feedback and make recommendations for improvements NS&T’s MOP.

  1. Infant observation: opportunities, challenges, threats

    OpenAIRE

    Hollway, Wendy

    2012-01-01

    This article reflects on the value of the infant observation tradition from the perspective of someone originally trained in scientific psychology and recently ending a four-year period as external examiner for the Masters and Diploma course in Psychoanalytic Observation at the Tavistock clinic. My aim is to convey, from the perspective of an outsider, how I came to appreciate the core insights that I learned from infant observation through my experience of them in a research context; to conv...

  2. Sequential measurements of conjugate observables

    Energy Technology Data Exchange (ETDEWEB)

    Carmeli, Claudio [Dipartimento di Fisica, Universita di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Heinosaari, Teiko [Department of Physics and Astronomy, Turku Centre for Quantum Physics, University of Turku, 20014 Turku (Finland); Toigo, Alessandro, E-mail: claudio.carmeli@gmail.com, E-mail: teiko.heinosaari@utu.fi, E-mail: alessandro.toigo@polimi.it [Dipartimento di Matematica ' Francesco Brioschi' , Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2011-07-15

    We present a unified treatment of sequential measurements of two conjugate observables. Our approach is to derive a mathematical structure theorem for all the relevant covariant instruments. As a consequence of this result, we show that every Weyl-Heisenberg covariant observable can be implemented as a sequential measurement of two conjugate observables. This method is applicable both in finite- and infinite-dimensional Hilbert spaces, therefore covering sequential spin component measurements as well as position-momentum sequential measurements.

  3. Mars Observer's Global Mapping Mission

    OpenAIRE

    Albee, A. L.; Palluconi, D. F.

    1990-01-01

    The Mars Observer mission, scheduled for launch in September 1992, will provide an orbital platform at Mars from which the entire Martian surface and atmosphere will be observed beginning in late 1993. Mars Observer will extend the exploration and characterization of Mars by providing new and systematic measurements of the surface and atmosphere of the planet. These measurements will be made from a low-altitude polar orbiter over a period of one Martian year (687 Earth days), permitting repet...

  4. Observability of Inertial Navigation System

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To improve the observability of strapdown inertial navigation system and the effectiveness of Kalman filter in the navigation system, the method of estimating the observability is analyzed based on eigenvalues and eigenvectors which are proved to be availabe, on this basis two-position alignment technigue is applied. The simulation shows that two-position alignment really makes the system's observability change from being incomplete to being complete, and the test method based on eigenvalues and eigenvectors is available to determine the observability of every state vector.

  5. Earth observation Water Cycle Multi-Mission Observation Strategy (WACMOS

    Directory of Open Access Journals (Sweden)

    Z. Su

    2010-10-01

    Full Text Available Observing and monitoring the different components of the global water cycle and their dynamics are essential steps to understand the climate of the Earth, forecast the weather, predict natural disasters like floods and droughts, and improve water resources management. Earth observation technology is a unique tool to provide a global understanding of many of the essential variables governing the water cycle and monitor their evolution over time from global to basin scales. In the coming years an increasing number of Earth observation missions will provide an unprecedented capacity to quantify several of these variables on a routine basis. In this context, the European Space Agency (ESA, in collaboration with the Global Energy and Water Cycle Experiment (GEWEX of the World Climate Research Program (WCRP, launched the Water Cycle Multi-Mission Observation Strategy (WACMOS project in 2009. The project aims at developing and validating a novel set of geo-information products relevant to the water cycle covering the following thematic areas: evapotranspiration, soil moisture, cloud characterization and water vapour. The generation of these products is based on a number of innovative techniques and methods aiming at exploiting the synergies of different types of Earth observation data available today to the science community. This paper provides an overview of the major findings of the project with the ultimate goal of demonstrating the potential of innovative multi-mission based strategies to improve current observations by maximizing the synergistic use of the different types of information provided by the currently available observation systems.

  6. Entropy of a Rindler Observer

    OpenAIRE

    Brauer, O.; Kirchuk, E.; Raviola, L.; Socolovsky, M.

    2013-01-01

    We compute the entropy of a Rindler particle-detector (observer) in the presence of a quantum field in the Minkowski vacuum state; due to the Unruh effect, the observer is immersed in a thermal bath at a temperature proportional to its proper acceleration.

  7. Teacher Observations for Diagnostic Teaching.

    Science.gov (United States)

    Saunders, Russell W., Jr.

    Teachers at the primary level should resume the neglected practice of diagnostic teaching. This means that the teacher should observe all aspects of a student's cognitive behavior in the teaching/learning act and then plan instructional strategies for subsequent lessons. Some significant cognitive behaviors observable in diagnostic teaching are…

  8. Pionic values for deuteron observables

    International Nuclear Information System (INIS)

    A method for an unambiguous determination of deuteron asymptotic observables due to one pion exchange is presented. With this purpose in mind, an almost purely one pion exchange potential (OPEP) deuteron was constructed to study relationship between the corresponding limiting values of the external observables and the pion-nucleon coupling constant. (R.P.) 8 refs., 4 figs

  9. Observable Effects of Quantum Gravity

    CERN Document Server

    Chang, Lay Nam; Sun, Chen; Takeuchi, Tatsu

    2016-01-01

    We discuss the generic phenomenology of quantum gravity and, in particular, argue that the observable effects of quantum gravity, associated with new, extended, non-local, non-particle-like quanta, and accompanied by a dynamical energy-momentum space, are not necessarily Planckian and that they could be observed at much lower and experimentally accessible energy scales.

  10. Information capacity of quantum observable

    CERN Document Server

    Holevo, A S

    2011-01-01

    In this paper we consider the classical capacities of quantum-classical channels corresponding to measurement of observables. Special attention is paid to the case of continuous observables. We give the formulas for unassisted and entanglement-assisted classical capacities $C,C_{ea}$ and consider some explicitly solvable cases which give new examples of entanglement-breaking channels with $C_{ea}>C.$

  11. Observing Teaching. SEDA Paper 79.

    Science.gov (United States)

    Brown, Sally, Ed.; And Others

    This publication offers practical support to those in British higher education implementing the Observation of Teaching governmental directives. It provides discussion of key issues as well as a range of materials on how to carry out teaching observation including 23 checklists. The materials are grouped in four main areas: general issues, self…

  12. Loop quantum gravity and observations

    OpenAIRE

    Barrau, A.; Grain, J.

    2014-01-01

    Quantum gravity has long been thought to be completely decoupled from experiments or observations. Although it is true that smoking guns are still missing, there are now serious hopes that quantum gravity phenomena might be tested. We review here some possible ways to observe loop quantum gravity effects either in the framework of cosmology or in astroparticle physics.

  13. Information capacity of quantum observable

    OpenAIRE

    Holevo, A. S.

    2011-01-01

    In this paper we consider the classical capacities of quantum-classical channels corresponding to measurement of observables. Special attention is paid to the case of continuous observables. We give the formulas for unassisted and entanglement-assisted classical capacities $C,C_{ea}$ and consider some explicitly solvable cases which give simple examples of entanglement-breaking channels with $C

  14. Timed Testing under Partial Observability

    DEFF Research Database (Denmark)

    David, Alexandre; Larsen, Kim Guldstrand; Li, Shuhao;

    2009-01-01

    observability of SUT using a set of predicates over the TGA state space, and specify the test purposes in Computation Tree Logic (CTL) formulas. A recently developed partially observable timed game solver is used to generate winning strategies, which are used as test cases. We propose a conformance testing...... framework, define a partial observation-based conformance relation, present the test execution algorithms, and prove the soundness and completeness of this test method (i.e., a detected error is really an error, and if the SUT violates the test purpose, then a test case can be generated to detect this......To steer model-based conformance testing of real-time systems towards certain test purposes or test coverage, many testing methods need (to be enhanced with) the assumption of full observability of the System Under Test (SUT), which means that the tester can observe precisely what state or...

  15. Time generated by intrinsic observers

    CERN Document Server

    Svozil, Karl

    2009-01-01

    We shortly review the construction of knowledge by intrinsic observers. Intrinsic observers are embedded in a system and are inseparable parts thereof. The intrinsic viewpoint has to be contrasted with an extrinsic, "God's eye" viewpoint, from which the system can be observed externally without in any way changing it. This epistemological distinction has concrete, formalizable consequences. One consequence is the emergence of "complementarity" for intrinsic observers, even if the underlying system is totally deterministic (computable). Another consequence is the appearence of time and inertial frames for intrinsic observers. The necessary operational techniques are developed in the context of Cellular Automata. We finish with a somewhat speculative question. Given space-time frames generated by clocks which use sound waves for synchronization; why could supersonic travel not cause time paradoxes?

  16. Earth observation Water Cycle Multi-Mission Observation Strategy (WACMOS)

    OpenAIRE

    Su, Z.; Dorigo, W; D. Fernández-Prieto; Van Helvoirt, M; K. Hungershoefer; Jeu, R.; Parinussa, R.; Timmermans, J; R. Roebeling; Schröder, M.; Schulz, J.; Van Der Tol, C.; P. Stammes; Wagner, W.; Wang, L.

    2010-01-01

    Observing and monitoring the different components of the global water cycle and their dynamics are essential steps to understand the climate of the Earth, forecast the weather, predict natural disasters like floods and droughts, and improve water resources management. Earth observation technology is a unique tool to provide a global understanding of many of the essential variables governing the water cycle and monitor their evolution over time from global to basin scales. In the coming years ...

  17. GEO Debris Observation of PMO

    Science.gov (United States)

    Ping, Yiding; Zhao, Changyin; Zhao, Haibin

    2009-03-01

    This paper summarizes observations and results obtained by Purple Mountain Observatory in March 2007 of space debris at geosynchronous orbit (GEO) in support of WG1 Action Item 23.4, International 2007 Optical Debris Campaign in Higher Earth Orbit, organized by the Inter-Agency Space Debris Coordination Committee (IADC). The main goal of Pmo's work is to develop the observational techniques of Higher Earth Orbit Space debris for the future work. A new telescope designed for debris observation is also described here.

  18. The ESO Observing Programmes Committee

    Science.gov (United States)

    Westerlund, B. E.

    1982-06-01

    Since 1978 the ESO Observing Programmes Committee (OPC) has "the function to inspect and rank the proposals made for observing programmes at La Silla, and thereby to advise the Director General on the distribution of observing time". The members (one from each member country) and their alternates are nominated by the respective national committees for five-year terms (not immediately renewable). The terms are staggered so that each year one or two persons are replaced. The Chairman is appointed annually by the Council. He is invited to attend Council meetings and to report to its members.

  19. Early Pulsar Observations with LOFAR

    CERN Document Server

    Hessels, Jason; Alexov, Anastasia; Coenen, Thijs; Hassall, Tom; Karastergiou, Aris; Kondratiev, Vlad; Kramer, Michael; van Leeuwen, Joeri; Mol, Jan David; Noutsos, Aris; Weltevrede, Patrick

    2010-01-01

    This contribution to the proceedings of "A New Golden Age for Radio Astronomy" is simply intended to give some of the highlights from pulsar observations with LOFAR at the time of its official opening: June 12th, 2010. These observations illustrate that, though LOFAR is still under construction and astronomical commissioning, it is already starting to deliver on its promise to revolutionize radio astronomy in the low-frequency regime. These observations also demonstrate how LOFAR has many "next-generation" capabilities, such as wide-field multi-beaming, that will be vital to open a new Golden Age in radio astronomy through the Square Kilometer Array and its precursors.

  20. Observational constraints on cosmological superstrings

    CERN Document Server

    Sazhina, Olga S

    2016-01-01

    From the theoretical point of view and not being in contradiction with current observational data, the cosmic strings may have fundamentally different origin and are characterized by wide range of energies. The paper is devoted to the search for possible cosmological observational tests on superstring theory, among them to the identification of observational characteristics to distinguish between cosmological superstring of different types. In the brane-world scenario with an assumption of creation of cosmological superstrings it was obtained the lower limit on the superstring tension as function of its deficit angle.

  1. Observational methodology in sport sciences

    Directory of Open Access Journals (Sweden)

    M. Teresa Anguera

    2013-11-01

    Full Text Available This paper reviews the conceptual framework, the key literature and the methods (observation tools, such as category systems and field formats, and coding software, etc. that should be followed when conducting research from the perspective of observational methodology. The observational designs used by the authors’ research group over the last twenty years are discussed, and the procedures for analysing data and assessing their quality are described. Mention is also made of the latest methodological trends in this field, such as the use of mixed methods.

  2. Overview of Saturn lightning observations

    CERN Document Server

    Fischer, G; Kurth, W S; Gurnett, D A; Zarka, P; Barry, T; Delcroix, M; Go, C; Peach, D; Vandebergh, R; Wesley, A

    2011-01-01

    The lightning activity in Saturn's atmosphere has been monitored by Cassini for more than six years. The continuous observations of the radio signatures called SEDs (Saturn Electrostatic Discharges) combine favorably with imaging observations of related cloud features as well as direct observations of flash-illuminated cloud tops. The Cassini RPWS (Radio and Plasma Wave Science) instrument and ISS (Imaging Science Subsystem) in orbit around Saturn also received ground-based support: The intense SED radio waves were also detected by the giant UTR-2 radio telescope, and committed amateurs observed SED-related white spots with their backyard optical telescopes. Furthermore, the Cassini VIMS (Visual and Infrared Mapping Spectrometer) and CIRS (Composite Infrared Spectrometer) instruments have provided some information on chemical constituents possibly created by the lightning discharges and transported upward to Saturn's upper atmosphere by vertical convection. In this paper we summarize the main results on Satur...

  3. COOP Wind and Radiation Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind and radiation data from stations in the National Weather Service Cooperative Observers Network. Some precipitation and pressure forms are mistakenly placed in...

  4. Mobile Source Observation Database (MSOD)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Mobile Source Observation Database (MSOD) is a relational database being developed by the Assessment and Standards Division (ASD) of the US Environmental...

  5. Archetypal Analysis for Nominal Observations.

    Science.gov (United States)

    Seth, Sohan; Eugster, Manuel J A

    2016-05-01

    Archetypal analysis is a popular exploratory tool that explains a set of observations as compositions of few 'pure' patterns. The standard formulation of archetypal analysis addresses this problem for real valued observations by finding the approximate convex hull. Recently, a probabilistic formulation has been suggested which extends this framework to other observation types such as binary and count. In this article we further extend this framework to address the general case of nominal observations which includes, for example, multiple-option questionnaires. We view archetypal analysis in a generative framework: this allows explicit control over choosing a suitable number of archetypes by assigning appropriate prior information, and finding efficient update rules using variational Bayes'. We demonstrate the efficacy of this approach extensively on simulated data, and three real world examples: Austrian guest survey dataset, German credit dataset, and SUN attribute image dataset. PMID:27046837

  6. Sliding mode control and observation

    CERN Document Server

    Shtessel, Yuri; Fridman, Leonid; Levant, Arie

    2014-01-01

    The sliding mode control methodology has proven effective in dealing with complex dynamical systems affected by disturbances, uncertainties and unmodeled dynamics. Robust control technology based on this methodology has been applied to many real-world problems, especially in the areas of aerospace control, electric power systems, electromechanical systems, and robotics. Sliding Mode Control and Observation represents the first textbook that starts with classical sliding mode control techniques and progresses toward newly developed higher-order sliding mode control and observation algorithms and their applications. The present volume addresses a range of sliding mode control issues, including: *Conventional sliding mode controller and observer design *Second-order sliding mode controllers and differentiators *Frequency domain analysis of conventional and second-order sliding mode controllers *Higher-order sliding mode controllers and differentiators *Higher-order sliding mode observers *Sliding mode disturbanc...

  7. CalNex Observational Data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Observations made during the 2010 CalNex measurement campaign. This dataset is associated with the following publication: Woody , M., K. Baker , P. Hayes, J....

  8. Historical Sunspot Observations: A Review

    CERN Document Server

    Vaquero, J M

    2007-01-01

    Early observations of sunspot were realised by the naked eye. Possible utilization of these records for studying the long-term change in the Sun is discussed here. Other historical sunspot observations with camera obscuras are also discussed. Moreover, the best record of the behaviour of the Sun exists for the last four centuries thanks to the observations of sunspots with telescope. These observations should allow us to know the number, position, and area of sunspots as well as some relevant episodes (Maunder Minimum, optical flares, etc.). Rudolf Wolf developed the first reconstruction of solar activity in the 19th century. The next reconstruction was made by Hoyt and Schatten in 1998 by improving the database and using a new methodological approach. Here some mistakes, pending tasks and minor improvements are discussed.

  9. Observability during planetary approach navigation

    Science.gov (United States)

    Bishop, Robert H.; Burkhart, P. Daniel; Thurman, Sam W.

    1993-01-01

    The objective of the research is to develop an analytic technique to predict the relative navigation capability of different Earth-based radio navigation measurements. In particular, the problem is to determine the relative ability of geocentric range and Doppler measurements to detect the effects of the target planet gravitational attraction on the spacecraft during the planetary approach and near-encounter mission phases. A complete solution to the two-dimensional problem has been developed. Relatively simple analytic formulas are obtained for range and Doppler measurements which describe the observability content of the measurement data along the approach trajectories. An observability measure is defined which is based on the observability matrix for nonlinear systems. The results show good agreement between the analytic observability analysis and the computational batch processing method.

  10. Surface Weather Observations (Pre-1893)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly weather records from U.S. Army Forts stations (~1820-1871), U.S. Army Signal Service Stations (1871-1892), Smithsonian Institution voluntary observer...

  11. Symbolic computations of nonlinear observability

    Science.gov (United States)

    Bianco-Martinez, Ezequiel; Baptista, Murilo S.; Letellier, Christophe

    2015-06-01

    Observability is a very useful concept for determining whether the dynamics of complicated systems can be correctly reconstructed from a single (univariate or multivariate) time series. When the governing equations of dynamical systems are high-dimensional and/or rational, analytical computations of observability coefficients produce large polynomial functions with a number of terms that become exponentially large with the dimension and the nature of the system. In order to overcome this difficulty, we introduce here a symbolic observability coefficient based on a symbolic computation of the determinant of the observability matrix. The computation of such coefficients is straightforward and can be easily analytically carried out, as demonstrated in this paper for a five-dimensional rational system.

  12. The Sprite 2005 Observation Campaign

    DEFF Research Database (Denmark)

    Chanrion, Olivier Arnaud; Crosby, Norma; Armone, Enrico;

    2007-01-01

    -month duration of this campaign, all of them took turns in operating the system and making their own night observations. The ongoing campaign activities were constantly advertised and communicated via an Internet blog. In summary the campaign required all the CAL young scientists to embark on experimental work...... outreach programmes for the young scientists hired. Educational activities were based on the following elements: national PhD programmes, activities at CAL and other meetings, a dedicated summer school, and two European sprite observational campaigns. The young scientists were strongly involved in the...... latter and, as an example, the "EuroSprite2005" observational campaign is presented in detail. Some of the young scientists participated in the instrument set-up, others in the campaign logistics, some coordinated the observations, and others gathered the results to build a catalogue. During the four...

  13. Untrained Forward Observer (UFO) Translator

    OpenAIRE

    King, Regan

    2012-01-01

    MOVES Research & Education Systems Seminar: Presentation; Session 3c: Human Systems and Training (Operational Systems); Moderator: Mike McCauley; Untrained Forward Observer (UFO) Translator; speaker: Capt. Regan R. King

  14. GODAE, SFCOBS - Surface Temperature Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GODAE, SFCOBS - Surface Temperature Observations: Ship, fixed/drifting buoy, and CMAN in-situ surface temperature. Global Telecommunication System (GTS) Data. The...

  15. Observing cosmic rays in space

    International Nuclear Information System (INIS)

    Direct measurement of the charged cosmic radiation (cosmic ray) impinging on Earth, play an essential role to get information of the acceleration and propagation mechanism by providing the relative abundance and the energy spectra. Observations, using balloon-borne detector, in Japan were historically achieved especially in field of the high energy electrons and hadrons. Since 2000, the cosmic ray observation in worldwide has done a remarkable progress by development of the detectors with high-technology electronics system and by success of the long duration ballooning, such as, in Antarctica. Further space observations planned at International Space Station will challenge to resolve the puzzles of the dark matter and the anti-matter in universe. The achievements of the direct observations by present days and the future prospect will briefly be reviewed in this article. (author)

  16. Bulletin of International Simultaneous Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The publication of the Bulletin of International Simultaneous Observations, began July 1, 1875, with daily maps added in 1877. It was published for distribution...

  17. Shell structure from nuclear observables

    Science.gov (United States)

    Bentley, I.; Rodríguez, Y. Colón; Cunningham, S.; Aprahamian, A.

    2016-04-01

    The appearance and disappearance of shells and subshells are determined using a previously introduced method of structural analysis. This work extends the approach and applies it to protons, in addition to neutrons, in an attempt to provide a more complete understanding of shell structure in nuclei. Experimental observables including the mean-square charge radius, as well as other spectroscopic and mass related quantities are analyzed for extrema. This analysis also uses differential observables among adjacent even-even nuclei to serve as the derivatives for these quantities of interest. Local extrema in these quantities indicate shell structure and the lack of local extrema indicate missing shell closures. The shell structure of low-mass nuclei is inconsistent likely as a consequence of the single-particle structure. Additionally, multiple shell features occurring in midshell regions are determined by combining information from two or more observables. Our results near stability complement previous observations further out.

  18. Observability transition in real networks

    CERN Document Server

    Yang, Yang

    2016-01-01

    We consider the observability model in networks with arbitrary topologies. We introduce a system of coupled nonlinear equations, valid under the locally tree-like ansatz, to describe the size of the largest observable cluster as a function of the fraction of directly observable nodes present in the network. We perform a systematic analysis on 95 real-world graphs and compare our theoretical predictions with numerical simulations of the observability model. Our method provides almost perfect predictions in the majority of the cases, even for networks with very large values of the clustering coefficient. Potential applications of our theory include the development of efficient and scalable algorithms for real-time surveillance of social networks, and monitoring of technological networks.

  19. An introduction to observational astrophysics

    CERN Document Server

    Gallaway, Mark

    2016-01-01

    Observational Astrophysics follows the general outline of an astrophysics undergraduate curriculum targeting practical observing information to what will be covered at the university level. This includes the basics of optics and coordinate systems to the technical details of CCD imaging, photometry, spectography and radio astronomy.  General enough to be used by students at a variety of institutions and advanced enough to be far more useful than observing guides targeted at amateurs, the author provides a comprehensive and up-to-date treatment of observational astrophysics at undergraduate level to be used with a university’s teaching telescope.  The practical approach takes the reader from basic first year techniques to those required for a final year project. Using this textbook as a resource, students can easily become conversant in the practical aspects of astrophysics in the field as opposed to the classroom.

  20. Observations afield on Alaskan wolves

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Widespread observations of wolves and their habits in Alaska during the period 1948-1954 generally confirm published reports of these phenomena elsewhere....