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Sample records for dual-beam arecibo uhf

  1. The Arecibo Dual-Beam Survey The HI Mass Function of Galaxies

    CERN Document Server

    Schneider, S E; Schneider, Jessica L. Rosenberg & Stephen E.

    2002-01-01

    We use the HI-selected galaxy sample from the Arecibo Dual-Beam Survey (Rosenberg & Schneider 2000) to determine the shape of the HI mass function of galaxies in the local universe using both the step-wise maximum likelihood and the 1/V_tot methods. Our survey region spanned all 24 hours of right ascension at selected declinations between 8 and 29 degrees covering ~430 deg^2 of sky in the main beam. The survey is not as deep as some previous Arecibo surveys, but it has a larger total search volume and samples a much larger area of the sky. We conducted extensive tests on all aspects of the galaxy detection process, allowing us to empirically correct for our sensitivity limits, unlike the previous surveys. The mass function for the entire sample is quite steep, with a power-law slope of \\alpha ~ -1.5. We find indications that the slope of the HI mass function is flatter near the Virgo cluster, suggesting that evolutionary effects in high density environments may alter the shape of the HI mass function. The...

  2. Dual-beam measurements of gravity waves over Arecibo: Reevaluation of wave structure, dynamics, and momentum fluxes

    Science.gov (United States)

    Fritts, David C.; Janches, Diego

    2008-03-01

    A previous study by Zhou and Morton (2006) employed dual-beam incoherent scatter radar measurements of radial velocities at the Arecibo Observatory to study the structure, dynamics, and momentum fluxes of gravity waves in the mesosphere and lower thermosphere for ˜8 h on 28 July 2001. Because of erroneous assumptions about wave character and inferences of the relationship between radial velocities, however, the advertised results of this previous study are largely in error. The purposes of the present study are both to point out these errors to help avoid such pitfalls in the future and to provide a new interpretation of these data, which represent a very interesting case study of gravity wave dynamics at these altitudes. Specific findings of the present study (largely in contradiction to the previous analysis) include (1) the ˜15-min oscillation was apparently a large-amplitude Doppler-ducted gravity wave structure propagating at one or two maxima of the westward large-scale wind present during the event; (2) the gravity wave exhibited a deep and coherent vertical phase structure, except between the two westward wind maxima at later times, entirely inconsistent with proximity to a critical level; (3) the dominant motions within the gravity wavefield were vertical velocities up to ˜10 m s-1, except for inferred horizontal motions where the vertical motions changed phase and above and below the vertical velocity maxima, as dictated by the continuity equation; (4) there were likely no regions of dynamical instability accompanying these ducted wave motions; and (5) momentum fluxes due to this wave motion were small, despite its very large amplitude.

  3. Meteoroid Fragmentation as Revealed in Head- and Trail-Echoes Observed with the Arecibo UHF and VHF Radars

    Science.gov (United States)

    Mathews, J. D.; Malhorta, A.

    2011-01-01

    We report recent 46.8/430 MHz (VHF/UHF) radar meteor observations at Arecibo Observatory (AO) that reveal many previously unreported features in the radar meteor return - including flare-trails at both UHF and VHF - that are consistent with meteoroid fragmentation. Signature features of fragmentation include strong intra-pulse and pulse-to-pulse fading as the result of interference between or among multiple meteor head-echo returns and between head-echo and impulsive flare or "point" trail-echoes. That strong interference fading occurs implies that these scatterers exhibit well defined phase centers and are thus small compared with the wavelength. These results are consistent with and offer advances beyond a long history of optical and radar meteoroid fragmentation studies. Further, at AO, fragmenting and flare events are found to be a large fraction of the total events even though these meteoroids are likely the smallest observed by the major radars. Fragmentation is found to be a major though not dominate component of the meteors observed at other HPLA radars that are sensitive to larger meteoroids.

  4. 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

  5. Arecibo Observatory for All

    Science.gov (United States)

    Isidro, Gloria M.; Pantoja, C. A.; Bartus, P.; La Rosa, C.

    2006-12-01

    We describe new materials available at Arecibo Observatory for visitors with visual impairments. These materials include a guide in Braille that describes the telescope, some basic terms used in radio astronomy and frequently asked questions. We have also designed a tactile model of the telescope. We are interested that blind visitors can participate of the excitement of the visit to the worlds largest radio telescope. We would like to thank the "Fundacion Comunitaria de Puerto Rico" for the scholarship that allowed GMI to work on this project. We would like to express our gratitude to the Arecibo Observatory/NAIC for their support.

  6. Arecibo Observatory for All

    Science.gov (United States)

    Bartus, P.; Isidro, G. M.; La Rosa, C.; Pantoja, C. A.

    2007-01-01

    We describe new materials available at the Arecibo Observatory for visitors with visual impairments. These materials include a guide in Braille that describes the telescope, explains some basic terms used in radio astronomy, and lists frequently asked questions. We have also designed a tactile model of the telescope. Our interest is in enabling…

  7. Constructing Dual Beam Optical Tweezers for Undergraduate Biophysics Research

    Science.gov (United States)

    Daudelin, Brian; West-Coates, Devon; Del'Etoile, Jon; Grotzke, Eric; Paramanathan, Thayaparan

    Optical tweezing, or trapping, is a modern physics technique which allows us to use the radiation pressure from laser beams to trap micron sized particles. Optical tweezers are commonly used in graduate level biophysics research but seldom used at the undergraduate level. Our goal is to construct a dual beam optical tweezers for future undergraduate biophysical research. Dual beam optical tweezers use two counter propagating laser beams to provide a stronger trap. In this study we discuss how the assembly of the dual beam optical tweezers is done through three main phases. The first phase was to construct a custom compressed air system to isolate the optical table from the vibrations from its surroundings so that we can measure pico-newton scale forces that are observed in biological systems. In addition, the biomaterial flow system was designed with a flow cell to trap biomolecules by combining several undergraduate semester projects. During the second phase we set up the optics to image and display the inside of the flow cell. Currently we are in the process of aligning the laser to create an effective trap and developing the software to control the data collection. This optical tweezers set up will enable us to study potential cancer drug interactions with DNA at the single molecule level and will be a powerful tool in promoting interdisciplinary research at the undergraduate level.

  8. [Design of Dual-Beam Spectrometer in Spectrophotometer for Colorimetry].

    Science.gov (United States)

    Liu, Yi-xuan; Yan, Chang-xiang

    2015-07-01

    Spectrophotometers for colorimetry are usually composed of two independent and identical spectrometers. In order to reduce the volume of spectrophotometer for colorimetry, a design method of double-beam spectrometer is put forward. A traditional spectrometer is modified so that a new spectrometer can realize the function of double spectrometers, which is especially suitable for portable instruments. One slit is replaced by the double-slit, than two beams of spectrum can be detected. The working principle and design requirement of double-beam spectrometer are described. A spectrometer of portable spectrophotometer is designed by this method. A toroidal imaging mirror is used for the Czerny-Turner double-beam spectrometer in this paper, which can better correct astigmatism, and prevent the dual-beam spectral crosstalk. The results demonstrate that the double-beam spectrometer designed by this method meets the design specifications, with the spectral resolution less than 10 nm, the spectral length of 9.12 mm, and the volume of 57 mm x 54 mm x 23 mm, and without the dual-beam spectral overlap in the detector either. Comparing with a traditional spectrophotometer, the modified spectrophotometer uses a set of double-beam spectrometer instead of two sets of spectrometers, which can greatly reduce the volume. This design method can be specially applied in portable spectrophotometers, also can be widely applied in other double-beam spectrophotometers, which offers a new idea for the design of dual-beam spectrophotometers.

  9. Dual-beam laser autofocusing system based on liquid lens

    Science.gov (United States)

    Zhang, Fumin; Yao, Yannan; Qu, Xinghua; Zhang, Tong; Pei, Bing

    2017-02-01

    A dual-beam laser autofocusing system is designed in this paper. The autofocusing system is based on a liquid lens with less moving parts and fast response time, which makes the system simple, reliable, compact and fast. A novel scheme "Time-sharing focus, fast conversion" is innovatively proposed. The scheme effectively solves the problem that the guiding laser and the working laser cannot focus at the same target point because of the existence of chromatic aberration. This scheme not only makes both guiding laser and working laser achieve optimal focusing in guiding stage and working stage respectively, but also greatly reduces the system complexity and simplifies the focusing process as well as makes autofocusing time of the working laser reduce to about 10 ms. In the distance range of 1 m to 30 m, the autofocusing spot size is kept under 4.3 mm at 30 m and just 0.18 mm at 1 m. The spot size is much less influenced by the target distance compared with the collimated laser with a micro divergence angle for its self-adaptivity. The dual-beam laser autofocusing system based on liquid lens is fully automatic, compact and efficient. It is fully meet the need of dynamicity and adaptivity and it will play an important role in a number of long-range control applications.

  10. 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.

  11. Dual-Beam Antenna Design for Autonomous Sensor Network Applications

    Directory of Open Access Journals (Sweden)

    Jean-Marie Floc'h

    2012-01-01

    Full Text Available This paper describes our contribution in the ANR project called CAPNET dedicated to the site security (autonomous sensor network. The network is autonomous in term of energy and it is very easy to deploy on the site (the time to deploy each node of the network is around 10 minutes. The first demonstrator was deployed in the fire base station of Brest, France with 10 nodes with a security perimeter around 1.5 km. Our contribution takes place in the field of antennas, with the development of two systems: a single-beam antenna reserved for the supervisor or the last node of the network, and a dual-beam antenna dedicated to the node in linear configuration. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT. The antennas have been designed and successfully measured.

  12. Target and structural materials under dual-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Camus, E.; Wanderka, N.; Wollenberger, H. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1995-11-01

    The European Spallation Source (ESS) is planned to have a beam power of 5 MW (3.75 mA of 1.334 GeV protons). This is by a factor 30 higher than the available most powerful spallation source ISIS at Rutherford-Appleton Lab. (RAL) in Great-Britain. This causes a damage rate of approx. 10 dpa (displacements per atom) per month in target materials (W or Ta) or structural materials. The problem of radiation damage by high energy protons in different alloys has been recently reviewed. At HMI, simulation irradiation using heavy ions and helium or hydrogen ions at the dual-beam facility are being out. Here, we report on some preliminary results obtained on tantalum as target material and on ferritic/martensitic steels (HT9 type steels or comparable steels), which are proposed to be used as structural materials. Goal of these investigations is to correlate the results with those obtained at spallation irradiated specimens and to investigate the unexplored field of simultaneous production of damage, helium and hydrogen at high levels. (author) 4 figs., 1 tab., 9 refs.

  13. The Arecibo Observatory Space Academy

    Science.gov (United States)

    Rodriguez-Ford, Linda A.; Fernanda Zambrano Marin, Luisa; Aponte Hernandez, Betzaida; Soto, Sujeily; Rivera-Valentin, Edgard G.

    2016-10-01

    The Arecibo Observatory Space Academy (AOSA) is an intense fifteen-week pre-college research program for qualified high school students residing in Puerto Rico, which includes ten days for hands-on, on site research activities. Our mission is to prepare students for their professional careers by allowing them to receive an independent and collaborative research experience on topics related to the multidisciplinary field of space science. 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) foster in every student an interest in the STEM fields by harnessing their natural curiosity and knowledge in order to further develop their critical thinking and investigation skills. Students interested in participating in the program go through an application, interview and trial period before being offered admission. They are welcomed as candidates the first weeks, and later become cadets while experiencing designing, proposing, and conducting research projects focusing in fields like Physics, Astronomy, Geology, Chemistry, and Engineering. Each individual is evaluated with program compatibility based on peer interaction, preparation, participation, and contribution to class, group dynamics, attitude, challenges, and inquiry. This helps to ensure that specialized attention can be given to students who demonstrate a dedication and desire to learn. Deciding how to proceed in the face of setbacks and unexpected problems is central to the learning experience. At the end of the semester, students present their research to the program mentors, peers, and scientific staff. This year, AOSA students also focused on science communication and were trained by NASA's FameLab. Students additionally presented their research at this year's International Space Development Conference (ISDC), which was held in

  14. Final PSD Permit Extension Letter - Energy Answers Arecibo, LLC/Energy Answers Arecibo Puerto Rico Renewable Energy Project, PR

    Science.gov (United States)

    This page contains the Final PSD Permit Extension Letter for Energy Answers Arecibo Puerto Rico Renewable Energy Project, issued on April 10, 2017 and the EPA Public Announcement for Final PSD Permit Extension for Energy Answers Arecibo, PR.

  15. Attonewton force detection using microspheres in a dual-beam optical trap in high vacuum

    CERN Document Server

    Ranjit, Gambhir; Stutz, Jordan H; Cunningham, Mark; Geraci, Andrew A

    2015-01-01

    We describe the implementation of laser-cooled silica microspheres as force sensors in a dual-beam optical dipole trap in high vacuum. Using this system we have demonstrated trap lifetimes exceeding several days, attonewton force detection capability, and wide tunability in trapping and cooling parameters. Measurements have been performed with charged and neutral beads to calibrate the sensitivity of the detector. This work establishes the suitability of dual beam optical dipole traps for precision force measurement in high vacuum with long averaging times, and enables future applications including the study of gravitational inverse square law violations at short range, Casimir forces, acceleration sensing, and quantum opto-mechanics.

  16. Very large Arecibo-type telescopes

    Science.gov (United States)

    Drake, Frank D.

    1988-03-01

    The Arecibo-type radio telescope, based on a fixed spherical reflector, is a very effective design for a large radio telescope on the Moon. In such telescopes, major structural members are provided by the ground on which they are built, and thus are provided at no cost in materials or transportation. The strong compression members, the tall towers which support the suspended platform, are an expensive part of the Arecibo telescope. The need for such towers can be eliminated if a suitable valley or crater can be found wherein the rim of the depression can be used as the support point for the cables which support the suspended platform. With an Arecibo-type radio telescope on the Moon, there are no changing gravity loads because of the design and no changing wind loads because of the location; therefore, the only source of time variation in the telescope geometry is thermal changes. Calculations show that with conventional materials, such as steel, it should be possible to construct an Arecibo-type telescope with a reflector diameter of some 30 km on the Moon, and with a reflector diameter of some 60 to 90 km if materials of high specific strength are used.

  17. Extended Commissioning and Calibration of the Dual-Beam Imaging Polarimeter

    CERN Document Server

    Masiero, Joseph; Harrington, David; Lin, Haosheng

    2008-01-01

    In our previous paper (Masiero et al. 2007) we presented the design and initial calibrations of the Dual-Beam Imaging Polarimeter (DBIP), a new optical instrument for the University of Hawaii's 2.2 m telescope on the summit of Mauna Kea, Hawaii. In this followup work we discuss our full-Stokes mode commissioning including crosstalk determination and our typical observing methodology.

  18. 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.

  19. Proposal for a spaceborne dual-beam rain radar with Doppler capability

    Science.gov (United States)

    Amayenc, Paul; Testud, Jacques; Marzoug, Mongi

    1993-06-01

    The feasibility of adding a Doppler capability to a spaceborne dual-beam radar is discussed. The dual-beam Doppler radar is capable of determining two components of the air velocity: the along-track component of the horizontal air velocity and a component directed between 0 and 20 deg off the vertical. Both components can be calculated with an accuracy of about 1.2 m/s within each resolution cell in standard conditions. THese data can be used by monitoring the mesoscale wind field within stratiform precipitation areas, or by estimating the horizontal transport of vertical momentum associated with deep convection on the climatological level. It is concluded that implementation of the Doppler capability on the radar operating at 24 GHz seems to be possible without jeopardizing the primary objective, i.e., the rain rate estimate at the global scale using a stereo-radar algorithm.

  20. Dynamics analysis of microsphere in a dual-beam fiber-optic trap with transverse offset.

    Science.gov (United States)

    Chen, Xinlin; Xiao, Guangzong; Luo, Hui; Xiong, Wei; Yang, Kaiyong

    2016-04-04

    A comprehensive dynamics analysis of microsphere has been presented in a dual-beam fiber-optic trap with transverse offset. As the offset distance between two counterpropagating beams increases, the motion type of the microsphere starts with capture, then spiral motion, then orbital rotation, and ends with escape. We analyze the transformation process and mechanism of the four motion types based on ray optics approximation. Dynamic simulations show that the existence of critical offset distances at which different motion types transform. The result is an important step toward explaining physical phenomena in a dual-beam fiber-optic trap with transverse offset, and is generally applicable to achieving controllable motions of microspheres in integrated systems, such as microfluidic systems and lab-on-a-chip systems.

  1. Dual beam encoded extended fractional Fourier transform security hologram with in-built repositioning

    Indian Academy of Sciences (India)

    Amit K Sharma; D P Chhachhia; D Mohan; A K Aggarwal

    2008-01-01

    This paper describes a simple method for making dual beam encoded extended fractional Fourier transform (EFRT) security holograms. The hologram possesses different stages of encoding so that security features are concealed and remain invisible to the counterfeiter. These concealed and encoded anticounterfeit security features in the security hologram can only be read through a key hologram. Key hologram also facilitates in-built repositioning of security hologram. The method of fabrication, the principle of reconstruction and the experimental results are presented.

  2. Optical stretching of giant unilamellar vesicles with an integrated dual-beam optical trap.

    Science.gov (United States)

    Solmaz, Mehmet E; Biswas, Roshni; Sankhagowit, Shalene; Thompson, James R; Mejia, Camilo A; Malmstadt, Noah; Povinelli, Michelle L

    2012-10-01

    We have integrated a dual-beam optical trap into a microfluidic platform and used it to study membrane mechanics in giant unilamellar vesicles (GUVs). We demonstrate the trapping and stretching of GUVs and characterize the membrane response to a step stress. We then measure area strain as a function of applied stress to extract the bending modulus of the lipid bilayer in the low-tension regime.

  3. 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

  4. Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

    Energy Technology Data Exchange (ETDEWEB)

    Ott, Dino; Oddershede, Lene B., E-mail: oddershede@nbi.dk [Niels Bohr Institute (NBI), University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Reihani, S. Nader S. [Department of Physics, Sharif University of Technology, 11369-9161 Tehran (Iran, Islamic Republic of)

    2014-05-15

    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts.

  5. Arecibo Pulsar and Transient Surveys Using ALFA

    Science.gov (United States)

    Cordes, J. M.

    2008-02-01

    A large scale survey for pulsars and transients is being conducted at the Arecibo Observatory using the Arecibo L-band Feed Array (ALFA). Data acquisition so far has been with correlation spectrometers that analyze a 0.1 GHz bandwidth at 1.4 GHz. The 256 frequency channels limit dispersion smearing to 1.2 ms at DMmax = 103 pc cm-3 while the sampling interval of 64 μs equals the dispersion smearing at DM~54 pc cm-3, providing high sensitivity to millisecond pulsars with standard periods out to implied distances of several kpc at low Galactic latitudes. In early 2008, we will use a new set of polyphase filter bank systems that provide the same time and frequency resolutions but over ALFA's full 0.3 GHz bandwidth. Currently the survey covers sky positions within 5° of the Galactic plane that are reachable with Arecibo. Preliminary results are given for some of the discoveries made so far, which include millisecond pulsars, a relativistic binary pulsar, a likely counterpart of a Compton GRO/EGRET gamma-ray source, and transient pulsars (including `RRATs''). We discuss the methodology of the survey, which includes archival of raw survey data at the Cornell Center for Advanced Computing and processing at distributed sites. The survey and follow up observations, which include timing observations, multiwavelength searches for orbital companions in the case of binary pulsars, etc. are organized through the Pulsar-ALFA (PALFA) Consortium. We expect the Galactic plane survey to continue until at least 2010, most likely involving multiple passes on each sky position to optimize detection of variable sources. The ALFA system will also be used to survey intermediate Galactic latitudes for millisecond pulsars, relativistic binaries with large systemic velocities, and runaway pulsars that will escape the Galaxy.

  6. DualBeam metrology: a new technique for optimizing 0.13-um photo processes

    Science.gov (United States)

    Berger, Steven D.; Desloge, Denis; Virgalla, Robert J.; Davis, Todd; Paxton, Ted A.; Witko, David

    2001-08-01

    A DualBeam Metrology system was investigated for the application of obtaining 3-dimensional (3D) characterization of a 130 nm ground rule KrF photolithography process. Integrated circuit devices are 3-dimensional in structure and, hence, should be best characterized using 3-dimensional techniques to ensure adherence to the design architecture and the desired process window for manufacturing. The need for 3D metrology is further required for the characterization and monitoring of critical layer processes and equipment performance. The metrology used in this investigation is a novel technique for critical feature cross sectioning. The process for DualBeam metrology uses a focused ion beam (FIB) for milling or cutting the cross section through the photoresist or process film. An integrated scanning electron microscope (SEM) provides high-resolution imaging of the features, and a flexible automated metrology package collects and analyzes the data. To demonstrate the feasibility of the technique, critical dimension (CD) data and sidewall angle (SWA) measurements were captured from 130 nm lines and 150 nm contacts at 1:1 densities. The critical criteria for the characterization of the photolithography process window are CD control, depth of focus (DOF), exposure latitude, and feature sidewall angle or profile. Using the DualBeam technique, 2D and 3D data are captured on a single machine platform using a cut, look, and measure routine. A further benefit is the availability of high-resolution cross-sectional SEM images that can be used qualitatively to validate the quantitative data. The results presented here show the performance of this 130 nm ground rule process and the benefits of utilizing this efficient characterization technique.

  7. 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.

  8. The Arecibo Galaxy Environment Survey - V. The Virgo cluster (I)

    Science.gov (United States)

    Taylor, R.; Davies, J. I.; Auld, R.; Minchin, R. F.

    2012-06-01

    We present 21-cm observations of a 10 × 2 deg2 region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 289 sources are detected over the full redshift range (-2000 Fast ALFA (ALFALFA).

  9. 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....

  10. Enhanced photoelectric detection of NV magnetic resonances in diamond under dual-beam excitation

    Science.gov (United States)

    Bourgeois, E.; Londero, E.; Buczak, K.; Hruby, J.; Gulka, M.; Balasubramaniam, Y.; Wachter, G.; Stursa, J.; Dobes, K.; Aumayr, F.; Trupke, M.; Gali, A.; Nesladek, M.

    2017-01-01

    The core issue for the implementation of NV center qubit technology is a sensitive readout of the NV spin state. We present here a detailed theoretical and experimental study of NV center photoionization processes, used as a basis for the design of a dual-beam photoelectric method for the detection of NV magnetic resonances (PDMR). This scheme, based on NV one-photon ionization, is significantly more efficient than the previously reported single-beam excitation scheme. We demonstrate this technique on small ensembles of ˜10 shallow NVs implanted in electronic grade diamond (a relevant material for quantum technology), on which we achieve a cw magnetic resonance contrast of 9%—three times enhanced compared to previous work. The dual-beam PDMR scheme allows independent control of the photoionization rate and spin magnetic resonance contrast. Under a similar excitation, we obtain a significantly higher photocurrent, and thus an improved signal-to-noise ratio, compared to single-beam PDMR. Finally, this scheme is predicted to enhance magnetic resonance contrast in the case of samples with a high proportion of substitutional nitrogen defects, and could therefore enable the photoelectric readout of single NV spins.

  11. On-line Scanned Probe Microscopy Transparently Integrated with DualBeam SEM/FIB Systems

    Science.gov (United States)

    Ignatov, Andrey; Komissar, Anatoly; Lewis, Aaron

    2013-03-01

    A multifunctional scanning probe microscope (SPM) will be described that transparently integrates with a DualBeam SEM/FIB System. This is done without perturbing any of the capabilities of the Dual Beam in terms of detectors, gas injectors, analyzers etc while allowing for a completely exposed probe tip to be imaged online even with immersion objectives at working distances as short as 4 mm. In addition, the completely free motion of the rotation axis of the stage is maintained with the probe tip at the eucentric point, this makes it possible to orient the sample in any direction on any structure The X and Y scan range of the atomic force microscopic (AFM) imaging achieves 35 microns with rough motion over 10 millimeters. This permits the SPM to tilt into position perpendicular to the SEM or FIB or under an angle for rapid and accurate placement of the probe tip at or on structures such as biopolymeric materials that are nanometric in X, Y and Z extent. Thus, not only can a structure's nanometric height be accurately profiled but this can be accomplished with the on-line excellence of SEM for X, Y metrology. Furthermore, electron and ion beam sensitive samples can be imaged and characterized by AFM at high resolution.

  12. RTD application in low power UHF rectifiers

    Science.gov (United States)

    Sinyakin, V. Yu; Makeev, M. O.; Meshkov, S. A.

    2016-08-01

    In the current work, the problem of UHF RFID passive tag sensitivity increase is considered. Tag sensitivity depends on HF signal rectifier efficiency and antenna-rectifier impedance matching. Possibility of RFID passive tag sensitivity increase up to 10 times by means of RTD use in HF signal rectifier in comparison with tags based on Schottky barrier diode is shown.

  13. Reconstructing comptonization parameters using simulations of single frequency, dual-beam observations of galaxy clusters

    CERN Document Server

    Lew, Bartosz

    2016-01-01

    Systematical effects in dual-beam, differential, radio observations of extended objects are discussed in the context of the One Centimeter Receiver Array (OCRA). We use simulated samples of Sunyaev--Zel'dovich (SZ) galaxy clusters at low ($z<0.4$) and intermediate ($0.4

  14. Optomechanical dual-beam backaction-evading measurement beyond the rotating-wave approximation

    Science.gov (United States)

    Malz, Daniel; Nunnenkamp, Andreas

    2016-11-01

    We present the exact analytical solution of the explicitly time-periodic quantum Langevin equation describing the dual-beam backaction-evading measurement of a single mechanical oscillator quadrature due to V. B. Braginsky, Y. I. Vorontsov, and K. S. Thorne [Science 209, 547 (1980), 10.1126/science.209.4456.547] beyond the commonly used rotating-wave approximation. We show that counterrotating terms lead to extra sidebands in the optical and mechanical spectra and to a modification of the main peak. Physically, the backaction of the measurement is due to periodic coupling of the mechanical resonator to a light-field quadrature that only contains cavity-filtered shot noise. Since this fact is independent of other degrees of freedom the resonator might be coupled to, our solution can be generalized, including to dissipatively or parametrically squeezed oscillators, as well as recent two-mode backaction-evading measurements.

  15. Shock loading characteristics of Zr and Ti metals using dual beam velocimeter

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, A. K., E-mail: a-saxena@barc.gov.in; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2015-08-21

    The characteristics of titanium and zirconium metal foils under shock loading have been studied up to 16 GPa and 12 GPa pressure, respectively, using portable electric gun setup as projectile launcher. In these experiments, the capabilities of a single Fabry-Perot velocimeter have been enhanced by implementing it in dual beam mode to record the two velocity profiles on a single streak camera. The measured equation of state data for both the metals have been found to be well in agreement with the reported Hugoniot, within experimental accuracies. A phase transition from α to ω phase has been detected near to 11.4 GPa for titanium and 8.2 GPa for zirconium in the rising part of target-glass interface velocity profile.

  16. Quantification of SOFC anode microstructure based on dual beam FIB-SEM technique

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, Hiroshi; Kishimoto, Masashi; Hayashi, Daisuke; Saito, Motohiro; Yoshida, Hideo [Department of Aeronautics and Astronautics, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Shikazono, Naoki; Teshima, Hisanori; Matsuzaki, Katsuhisa; Kanno, Daisuke; Kasagi, Nobuhide [Department of Mechanical Engineering, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Matsui, Toshiaki; Kishida, Ryo; Muroyama, Hiroki; Eguchi, Koichi [Department of Energy and Hydrocarbon Chemistry, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2010-02-15

    The three-dimensional microstructure of an SOFC anode is quantified using a dual beam focused ion beam scanning electron microscopy (FIB-SEM) system equipped with an energy dispersive X-ray spectroscopy (EDX) unit. The microstructure of the Ni-YSZ anode is virtually reconstructed in a computational field using a series of acquired two-dimensional SEM images. The three-phase boundary (TPB) density and tortuosity factors are carefully evaluated by applying two different evaluation methods to each parameter. The TPB density is estimated by a volume expansion method and a centroid method, while the tortuosity factors are evaluated by a random walk calculation and a lattice Boltzmann method (LBM). Estimates of each parameter obtained by the two methods are in good agreement with each other, thereby validating the reliability of the analysis methods proposed in this study. (author)

  17. Measurements of urea and glucose in aqueous solutions with dual-beam near-infrared Fourier-transform spectroscopy

    DEFF Research Database (Denmark)

    Jensen, P.S.; Bak, J.

    2002-01-01

    of these two modes of operation. The concentrations of aqueous solutions of urea and glucose in the ranges 0-40 mg/dL and 0-250 mg/dL, respectively, were determined by principal component regression using both modes. The dual-beam technique eliminated instrumental variations present in the single...

  18. Cavity nucleation and growth in dual beam irradiated 316L industrial austenitic stainless steel

    Science.gov (United States)

    Jublot-Leclerc, S.; Li, X.; Legras, L.; Fortuna, F.; Gentils, A.

    2017-10-01

    Thin foils of 316L were simultaneously ion irradiated and He implanted in situ in a Transmission Electron Microscope at elevated temperatures. The resulting microstructure is carefully investigated in comparison with previous single ion irradiation experiments with a focus on the nucleation and growth of cavities. Helium is found to strongly enhance the nucleation of cavities in dual beam experiments. On the contrary, it does not induce more nucleation when implanted consecutively to an in situ ion irradiation but rather the growth of cavities by absorption at existing cavities, which shows the importance of synergistic effects and He injection mode on the microstructural changes. In both dual beam and single beam experiments, the characteristics of the populations of cavities, either stabilized by He or O atoms, are in qualitative agreement with the predictions of rate theory models for cavity growth. The evolutions of cavity population as a function of irradiation conditions can be reasonably well explained by the concept of relative sink strength of cavities and dislocations and the resulting partitioning of defects at sinks, or conversely recombination when either of the sinks dominates. The dislocations whose presence is a prerequisite to cavity growth in rate theory models are not observed in all studied conditions. In this case, the net influx of vacancies to cavities necessary to their growth and conversion to voids is believed to result from free surface effects, and possibly also segregation of elements close to the cavity surface. In any studied condition, the measured swelling is low, which is ascribed to the dilution of gaseous atoms among a high density of cavities as well as a high rate of point defect recombination and loss at traps. This high rate of recombination enhanced when dislocations are absent appears to result in the formation of overpressurized He bubbles.

  19. Radar observations of near-Earth asteroids from Arecibo Observatory

    Science.gov (United States)

    Rivera-Valentin, Edgard G.; Taylor, Patrick A.; Rodriguez-Ford, Linda A.; Zambrano Marin, Luisa Fernanda; Virkki, Anne; Aponte Hernandez, Betzaida

    2016-10-01

    The Arecibo S-Band (2.38 GHz, 12.6 cm, 1 MW) planetary radar system at the 305-m William E. Gordon Telescope in Arecibo, Puerto Rico is the most active and most sensitive planetary radar facility in the world. Since October 2015, we have detected 56 near-Earth asteroids, of which 17 are classified as potentially hazardous to Earth and 22 are compliant with the Near-Earth Object Human Space Flight Accessible Target Study (NHATS) as possible future robotic- or human-mission destinations. We will present a sampling of the asteroid zoo observed by the Arecibo radar since the 2015 DPS meeting. This includes press-noted asteroids 2015 TB145, the so-called "Great Pumpkin", and 2003 SD220, the so-called "Christmas Eve asteroid".

  20. 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.

  1. Pulsar Search Results from the Arecibo Remote Command Center

    Science.gov (United States)

    Garcia, Alejandro; Stovall, K.; Banaszak, S. A.; Becker, A.; Biwer, C. M.; Boehler, K.; Caballero, K.; Christy, B.; Cohen, S.; Crawford, F.; Cuellar, A.; Danford, A.; Dartez, L. P.; Day, D.; Flanigan, J. D.; Gonzalez, A.; Gustavson, K.; Handzo, E.; Hinojosa, J.; Jenet, F.; Kaplan, D. L.; Kayal, K.; Lommen, A. N.; Longoria, C.; Lopez, J.; Lunsford, G.; Mahany, N.; Martinez, J.; Mata, A.; Miller, A.; Murray, J.; Pankow, C.; Ramirez, I.; Reser, J.; Rojas, P.; Rohr, M.; Rolph, K.; Rose, C.; Rudnik, P.; Siemens, X.; Tellez, A.; Tillman, N.; Walker, A.; Wells, B. L.; Zermeno, A.; Consortium, GBNCC; Consortium, PALFA; Consortium, GBTDrift; Consortium, AO327

    2014-01-01

    The Arecibo Remote Command Center (ARCC) at the University of Texas at Brownsville, in collaboration with various Universities, is currently engaged in searching through ongoing radio telescope surveys for radio pulsars. ARCC is an integrated research/education program that allows students at the high school and undergraduate level to be directly involved with the research at the Arecibo and Green Bank radio telescopes. We discuss the progress of our search effort with PRESTO pulsar search pipelines. Web based tools have been developed so that high school, undergraduate, and graduate students could rank the pulsar candidates created by PRESTO pipelines. We describe these tools and present our current discoveries.

  2. Latest Results of the SETHI Survey at Arecibo

    Science.gov (United States)

    Korpela, E. J.; Demorest, P.; Heien, E.; Heiles, C.; Werthimer, D.

    2004-10-01

    SETH i is a survey of the distribution of galactic neutral hydrogen being performed comensally at the NAIC Arecibo Observatory. At the same time that observers use receivers in the Gregorian dome, SETHi is recording a 2.5MHz band centered at 1420 MHz from a flat feed on Carriage House 1. During normal astronomical observations, the SETH i feed scans across the sky at twice the sidereal rate. During 4 years of observations, we have accumulated over 15,000 hours of data covering most of the sky accessible to Arecibo. This survey has higher angular resolution than existing single dish surveys and higher sensitivity than existing or planned interferometric surveys.

  3. The Deep Interferometric VSOP--Arecibo Survey (DIVAS)

    Science.gov (United States)

    Edwards, P. G.; Hirabayashi, H.; Ulvestad, J. S.; Salter, C.; Ghosh, T.; Gurvits, L. I.; Fomalont, E. B.

    2009-08-01

    The Deep Interferometric VSOP-Arecibo Survey (DIVAS) program used space VLBI observations of a faint sample of flat-spectrum sources made with the HALCA satellite and the Arecibo telescope to provide the highest possible space VLBI sensitivity at 5 GHz. The main aim of the survey is to compare statistical results on the source structures (e.g., brightness temperatures, sizes, visibilities) with results from the VLBI Space Observatory Programme (VSOP) Survey, to determine whether there are systematic differences in the compact structures of sources selected from samples with limiting flux densities differing by over an order of magnitude.

  4. RFID UHF i HF w bibliotekach

    Directory of Open Access Journals (Sweden)

    Gładysz Bartłomiej

    2015-06-01

    Full Text Available The potential of the innovative Radio Frequency Identification (RFID technology to be applied for support, acceleration and automation of the circulation process of library collection is presented. Technology basics, and hardware and software components are described. Two different radio standards used in libraries are compared. The goal is to present the potential of RFID technology for libraries, to highlight the differences and to build a basis for further consideration of UHF and HF alternatives.

  5. Cutting-Edge Science from Arecibo Observatory: Introduction

    Science.gov (United States)

    Schmelz, Joan T.

    2017-01-01

    The Arecibo Observatory is home to the largest radio telescope in the world operating above 2 GHz, where molecule emission pertaining to the origins of life proliferate. It also houses the most powerful radar system on the planet, providing crucial information for the assessment of impact hazards of near-Earth asteroids (NEA). It was built to study the ionosphere with a radar system that can also monitor the effects of Space Weather and climate change. Arecibo has a proven track record for doing excellent science, even after 50 years of operations. This talk will include brief summaries of several Arecibo astronomy topics including the (1) latest attempts to resolve the Pleiades distance controversy, which include VLBI and Gaia; (2) galactic and extragalactic molecules; and (3) Arecibo 3D orbit determinations of potentially hazardous asteroids, and the crucial observation required to select Bennu as the target for the recently launched NASA OSIRIS-REx mission. This introduction will set the stage for the invited talks in this session, which include such topics as Fast Radio Bursts, galactic and extragalactic HI results, the pulsar emission problem, and NANOGrav. This work is supported by NSF and NASA.

  6. Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

    Science.gov (United States)

    Xie, Xin; Chen, Xu; Li, Junrui; Wang, Yonghong; Yang, Lianxiang

    2015-11-01

    Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential.

  7. Design of dual Beam multi-wavelength UV-visible absorbance detectors based on CCD

    Institute of Scientific and Technical Information of China (English)

    SHEN Shuang; TANG Zhen-an; LI Tong

    2006-01-01

    @@ Because the general multi-wavelength UV-Visible absorbance detector cannot avoid the noise and drift resulting from the intensity fluctuation of the light source,a dual beam multi-wavelength UV-Visible detector based on CCD was designed.The ray of light source is divided into a signal ray and a reference ray by the beam splitter after it passes through the chopper.The signal ray shines into the sample cell.The signal ray passing through the sample cell falls onto a concave mirror which focuses it onto a slot that is imaged on one portion of CCD by a concave grating.The reference ray is imaged on the other portion of CCD by the concave grating after the slot.The signal spectrum,the reference spectrum and the dark current of CCD can be measured on the same CCD under the cooperation of the optical system and accessorial circuits.The real-time compensation for the signal spectrum by using the reference spectrum and the dark current of CCD can effectively depress the noise and drift of the detector.The short-term noise is 10-5AU and the drift is 10-4AU/h.

  8. Microstructure evolution of selected ferritic-martensitic steels under dual-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wanderka, N.; Camus, E.; Wollenberger, H. [Hahn-Meitner-Inst. Berlin GmbH (Germany)

    1997-11-01

    The authors present experimental results on the microstructure evolution of dual-beam irradiated (300 keV heavy ions plus 15 keV helium ions) ferritic-martensitic steels (Manet, DIN 1.4926, F82H mod). The helium bubble morphology as well as microchemistry of the alloys are investigated by means of transmission electron microscopy and field-ion microscopy with atom probe. The alloys were irradiated to fluences up to 50 dpa and implanted with helium up to a concentration of 1 at.% at the temperatures of 723 K and 773 K. The damage and implantation rates varied from 2.5 {center_dot} 10{sup {minus}3} dpa/s to 2.5 {center_dot} 10{sup {minus}2} dpa/s and from 0.5 appm/s to 5 appm/s, respectively. Size and number density of helium bubbles is found to be rate dependent. Smaller implantation rates produce larger helium bubbles and smaller bubble number densities. Regions of local enrichment of alloy elements, typically 5 nm in size, containing chromium (up to 40 at.%), silicon, and nickel are detected. Number densities of helium bubbles and of regions of chromium enrichments are comparable and lie between 10{sup 23}/m{sup 3} and 10{sup 24}/m{sup 3}. Possible extrapolation of the present ion irradiations to spallation source and fusion reactor conditions is shortly addressed.

  9. Dual beam light profile microscopy: a new technique for optical absorption depth profilometry.

    Science.gov (United States)

    Power, J F; Fu, S W

    2004-02-01

    Light profile microscopy (LPM) is a recently developed technique of optical inspection that is used to record micrometer-scale images of thin-film cross-sections on a direct basis. In single beam mode, LPM provides image contrast based on luminescence, elastic, and/or inelastic scatter. However, LPM may also be used to depth profile the optical absorption coefficient of a thin film based on a method of dual beam irradiation presented in this work. The method uses a pair of collimated laser beams to consecutively irradiate a film from two opposing directions along the depth axis. An average profile of the beam's light intensity variation through the material is recovered for each direction and used to compute a depth-dependent differential absorbance profile. This latter quantity is shown from theory to be related to the film's depth-dependent optical absorption coefficient through a simple linear model that may be inverted by standard methods of numerical linear algebra. The inverse problem is relatively well posed, showing good immunity to data errors. This profilometry method is experimentally applied to a set of well-characterized materials with known absorption properties over a scale of tens of micrometers, and the reconstructed absorption profiles were found to be highly consistent with the reference data.

  10. Design & development of a galvanometer inspired dual beam optical coherence tomography system for flow velocity quantification of the microvasculature

    OpenAIRE

    McElligott-Daly, Susan; Jonathan, E.; Martin J. Leahy

    2011-01-01

    peer-reviewed This paper reports initial experimentation of a dual beam flow velocity estimation setup based on optical coherence tomography (OCT) for biomedical applications. The proposed work incorporates a low cost switching mechanism (rotating galvanometer mirror) for optical signal discrimination between adjacent fiber channels enabling quasisimultaneous multiple specimen scanning. A cascaded interferometric design is used with two sample output arms orientated in parallel to eacho...

  11. Cryo DualBeam Focused Ion Beam-Scanning Electron Microscopy to Evaluate the Interface Between Cells and Nanopatterned Scaffolds.

    Science.gov (United States)

    Lamers, Edwin; Walboomers, X Frank; Domanski, Maciej; McKerr, George; O'Hagan, Barry M; Barnes, Clifford A; Peto, Lloyd; Luttge, Regina; Winnubst, Louis A J A; Gardeniers, Han J G E; Jansen, John A

    2011-01-01

    With the advance of nanotechnology in biomaterials science and tissue engineering, it is essential that new techniques become available to observe processes that take place at the direct interface between tissue and scaffold materials. Here, Cryo DualBeam focused ion beam-scanning electron microscopy (FIB-SEM) was used as a novel approach to observe the interactions between frozen hydrated cells and nanometric structures in high detail. Through a comparison of images acquired with transmission electron microscopy (TEM), conventional FIB-SEM operated at ambient temperature, and Cryo DualBeam FIB-SEM, the advantages and disadvantages of each technique were evaluated. Ultrastructural details of both (extra)cellular components and cell organelles were best observe with TEM. However, processing artifacts such as shrinkage of cells at the substrate interface were introduced in both TEM and conventional FIB-SEM. In addition, the cellular contrast in conventional FIB-SEM was low; consequently, cells were difficult to distinguish from the adjoining substrate. Cryo DualBeam FIB-SEM did preserve (extra)cellular details like the contour, cell membrane, and mineralized matrix. The three described techniques have proven to be complementary for the evaluation of processes that take place at the interface between tissue and substrate.

  12. 47 CFR 73.4195 - Political advertising by UHF translators.

    Science.gov (United States)

    2010-10-01

    ... 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 FR... 47 Telecommunication 4 2010-10-01 2010-10-01 false Political advertising by UHF translators....

  13. 47 CFR 74.733 - UHF translator signal boosters.

    Science.gov (United States)

    2010-10-01

    ... EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.733 UHF translator signal boosters. (a) The licensee of a UHF... signal booster site. (j) The provisions of §§ 74.767 and 74.781 concerning marking and lighting...

  14. Ionospheric Impacts on UHF Space Surveillance

    Science.gov (United States)

    Jones, J.; Ceron-Gomez, D.; Richards, G.

    2016-09-01

    Earth's atmosphere contains regions of ionized plasma caused by the interaction of highly energetic solar radiation. This region of ionization is called the ionosphere and varies significantly with altitude, latitude, local solar time, season, and solar cycle. Significant ionization begins at about 100 km (E layer) with a peak in the ionization at about 350 km (F2 layer). Above the F2 layer, the atmosphere is mostly ionized but the ion and electron densities are low due to the unavailability of neutral molecules for ionization so the electron density decreases exponentially with height to well over 1000 km. The gradients of these variations in the ionosphere play a significant role in radio wave propagation. These gradients induce variations in the index of refraction and cause some radio waves to refract. The amount of refraction depends on the magnitude and direction of the electron density gradient and the frequency of the radio wave. The refraction is significant at HF frequencies (3-30 MHz) with decreasing effects toward the UHF (300-3000 MHz) range. UHF is commonly used for tracking of space objects in low Earth orbit (LEO). While ionospheric refraction is small for UHF frequencies, it can cause errors in range, azimuth angle, and elevation angle estimation by ground-based radars tracking space objects. These errors can cause significant uncertainty in precise orbit determinations. For radio waves transiting the ionosphere, it is important to understand and account for these effects. Using a sophisticated radio wave propagation tool suite and an empirical ionospheric model, we calculate the errors induced by the ionosphere in a simulation of a notional space surveillance radar tracking objects in LEO. These errors are analyzed to determine correlations with ionospheric variability. Corrections to surveillance radar measurements can be adapted from our simulation capability.

  15. 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.

  16. 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.

  17. Power Transmission of UHF Passive Embedded RFID in Tires

    OpenAIRE

    Shengbo Hu; Bing Si; Heng Shu; Jinrong Mo

    2014-01-01

    UHF passive RFID tags embedded in tires have a deep impact on tire life cycle management and tire monitoring. In this work, we present the power transmission of UHF passive embedded RFID in tires. In UHF passive embedded RFID systems in tires, the bidirectional radio link between reader and tags goes through air and tires. The total path loss contains reflection loss at tire-air boundaries and attenuation loss in the tires. The power transmission is based on the permittivity of tires and tire...

  18. Dual-beam optical coherence tomography system for quantification of flow velocity in capillary phantoms

    Science.gov (United States)

    Daly, S. M.; Silien, C.; Leahy, M. J.

    2012-03-01

    The quantification of (blood) flow velocity within the vasculature has potent diagnostic and prognostic potential. Assessment of flow irregularities in the form of increased permeability (micro haemorrhaging), the presence of avascular areas, or conversely the presence of vessels with enlarged or increased tortuosity in the acral regions of the body may provide a means of non-invasive in vivo assessment. If assessment of dermal flow dynamics were performed in a routine manner, the existence and prevalence of ailments such as diabetes mellitus, psoriatic arthritis and Raynaud's condition may be confirmed prior to clinical suspicion. This may prove advantageous in cases wherein the efficacy of a prescribed treatment is dictated by a prompt diagnosis and to alleviate patient discomfort through early detection. Optical Coherence Tomography (OCT) is an imaging modality which utilises the principle of optical interferometry to distinguish between spatial changes in refractive index within the vasculature and thus formulate a multi-dimensional representation of the structure of the epi- and dermal skin layers. The use of the Doppler functionality has been the predominant force for the quantification of moving particles within media, elucidated via estimation of the phase shift in OCT A-scans. However, the theoretical formulation for the assessment of these phase shifts dictates that the angle between the incident light source and the vessel under question be known a priori; this may be achieved via excisional biopsy of the tissue segment in question, but is counter to the non-invasive premise of the OCT technique. To address the issue of angular dependence, an alternate means of estimating absolute flow velocity is presented. The design and development of a dual-beam (db) system incorporating an optical switch mechanism for signal discrimination of two spatially disparate points enabling quasi-simultaneous multiple specimen scanning is described. A crosscorrelation (c

  19. VizieR Online Data Catalog: Arecibo Pulsar-ALFA (PALFA) survey. IV. (Lazarus+, 2015)

    Science.gov (United States)

    Lazarus, P.; Brazier, A.; 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.

    2016-02-01

    The Arecibo Pulsar-ALFA (PALFA) survey observations have been restricted to the two regions of the Galactic plane (|b|<5°) visible from the Arecibo observatory, the inner Galaxy (32°<~l<~77°), and the outer Galaxy (168°<~l<~214°). Integration times are 268s and 180s for inner and outer Galaxy observations, respectively. Observations conducted with the 7-beam Arecibo L-band Feed Array (ALFA) receiver of the Arecibo Observatory William E. Gordon 305m Telescope have a bandwidth of 322MHz centered at 1375MHz. PALFA survey data have been recorded with the Mock spectrometers since 2009. (2 data files).

  20. Screen printed UHF antennas on flexible substrates

    Science.gov (United States)

    Janeczek, Kamil; Młożniak, Anna; Kozioł, Grażyna; Araźna, Aneta; Jakubowska, Małgorzata; Bajurko, Paweł

    2010-09-01

    Printed electronics belongs to the most important developing electronics technologies. It provides new possibilities to produce low cost and large area devices. In its range several applications can be distinguished like printed batteries, OLED, biosensors, photovoltaic cells or RFID tags. In the presented investigation, antennas working in UHF frequency range were elaborated. It can be applied in the future for flexible RFID tags. To produce these antennas polymer paste with silver flakes was used. It was deposited on two flexible substrates (foil and photo paper) with screen printing techniques. After printing process surface profile, electrical and microwave parameters of performed antennas were measured using digital multimeter and network analyzer, relatively. Furthermore, a thickness of printed layers was measured.

  1. 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...

  2. Exploring RSSI Dependency on Height in UHF for throughput optimisation

    CSIR Research Space (South Africa)

    Maliwatu, R

    2016-11-01

    Full Text Available International Conference on Advances in Computing & Communication Engineering (ICACCE), 28-29 November 2016, Durban, South Africa Exploring RSSI Dependency on Height in UHF for throughput optimisation Richard Maliwatu Albert Lysko David Johnson...

  3. Assessment of Multipath and Shadowing Effects on UHF Band in ...

    African Journals Online (AJOL)

    Sultan

    areas where diverse obstacles such as large buildings, trees, moving objects and hills are present along the ... analysis in built-up environments. ... using four television transmitters at UHF bands along four major routes of Osun State, Nigeria.

  4. Effects of beam configurations on wire melting and transfer behaviors in dual beam laser welding with filler wire

    Science.gov (United States)

    Ma, Guolong; Li, Liqun; Chen, Yanbin

    2017-06-01

    Butt joints of 2 mm thick stainless steel with 0.5 mm gap were fabricated by dual beam laser welding with filler wire technique. The wire melting and transfer behaviors with different beam configurations were investigated detailedly in a stable liquid bridge mode and an unstable droplet mode. A high speed video system assisted by a high pulse diode laser as an illumination source was utilized to record the process in real time. The difference of welding stability between single and dual beam laser welding with filler wire was also compartively studied. In liquid bridge transfer mode, the results indicated that the transfer process and welding stability were disturbed in the form of "broken-reformed" liquid bridge in tandem configuration, while improved by stabilizing the molten pool dynamics with a proper fluid pattern in side-by-side configuration, compared to sigle beam laser welding with filler wire. The droplet transfer period and critical radius were studied in droplet transfer mode. The transfer stability of side-by-side configuration with the minium transfer period and critical droplet size was better than the other two configurations. This was attributed to that the action direction and good stability of the resultant force which were beneficial to transfer process in this case. The side-by-side configuration showed obvious superiority on improving welding stability in both transfer modes. An acceptable weld bead was successfully generated even in undesirable droplet transfer mode under the present conditions.

  5. Dual-beam ELF wave generation as a function of power, frequency, modulation waveform, and receiver location

    Science.gov (United States)

    Agrawal, D.; Moore, R. C.

    2012-12-01

    Dual-beam ELF wave generation experiments performed at the High-frequency Active Auroral Research Program (HAARP) HF transmitter are used to investigate the dependence of the generated ELF wave magnitude on HF power, HF frequency, modulation waveform, and receiver location. During the experiments, two HF beams transmit simultaneously: one amplitude modulated (AM) HF beam modulates the conductivity of the lower ionosphere at ELF frequencies while a second HF beam broadcasts a continuous waveform (CW) signal, modifying the efficiency of ELF conductivity modulation and thereby the efficiency of ELF wave generation. We report experimental results for different ambient ionospheric conditions, and we interpret the observations in the context of a newly developed dual-beam HF heating model. A comparison between model predictions and experimental observations indicates that the theoretical model includes the essential physics involved in multifrequency HF heating of the lower ionosphere. In addition to the HF transmission parameters mentioned above, the model is used to predict the dependence of ELF wave magnitude on the polarization of the CW beam and on the modulation frequency of the modulated beam. We consider how these effects vary with ambientD-region electron density and electron temperature.

  6. Power Transmission of UHF Passive Embedded RFID in Tires

    Directory of Open Access Journals (Sweden)

    Shengbo Hu

    2014-01-01

    Full Text Available UHF passive RFID tags embedded in tires have a deep impact on tire life cycle management and tire monitoring. In this work, we present the power transmission of UHF passive embedded RFID in tires. In UHF passive embedded RFID systems in tires, the bidirectional radio link between reader and tags goes through air and tires. The total path loss contains reflection loss at tire-air boundaries and attenuation loss in the tires. The power transmission is based on the permittivity of tires and tire-air boundary conditions. We give an OCP method for measuring the permittivity of tires. By analyzing the radio link for UHF passive RFID, we establish a model of wave propagation of UHF embedded RFID in tires and make numerical analyses. Numerical analyses show that the error of the OCP methods for measuring the permittivity of tires is small, the parallel polarization and normal incidence of wave are chosen for improving the performance of the UHF embedded RFID in tires, and distance is chosen to keep power transmission function from locating valley.

  7. H-alpha response to geomagnetic disturbed activity at Arecibo.

    Science.gov (United States)

    Santos, Pedrina; Kerr, R.; Noto, J.; Brum, Christiano; Gonzalez, Sixto

    Configured with a spectral resolution of 0.0086 nm at 6563A, the low resolution Fabry-Perot Interferometer (FPI) installed at Arecibo Observatory sampled the geocoronal Balmer-alpha emission for sixty nights during new moon periods from September 2006 to September 2007. In this work two of these periods are analyzed according to the variability with the geomagnetic activity. With this purpose, the effect of the shadow height, local time and solar flux depen-dencies were found and isolated and only the possible variations due the geomagnetic activity were evaluated. The residuos of the relative H-alpha intensity and temperature are analyzed.

  8. Arecibo PALFA survey and Einstein@Home: binary pulsar discovery by volunteer computing

    NARCIS (Netherlands)

    Knispel, B.; Lazarus, P.; Allen, B.; Anderson, D.; Aulbert, C.; Bhat, N.D.R.; Bock, O.; Bogdanov, S.; Brazier, A.; Camilo, F.; Chatterjee, S.; Cordes, J.M.; Crawford, F.; Deneva, J.S.; Desvignes, G.; Fehrmann, H.; Freire, P.C.C.; Hammer, D.; Hessels, J.W.T.; Jenet, F.A.; Kaspi, V.M.; Kramer, M.; van Leeuwen, J.; Lorimer, D.R.; Lyne, A.G.; Machenschalk, B.; McLaughlin, M.A.; Messenger, C.; Nice, D.J.; Papa, M.A.; Pletsch, H.J.; Prix, R.; Ransom, S.M.; Siemens, X.; Stairs, I.H.; Stappers, B.W.; Stovall, K.; Venkataraman, A.

    2011-01-01

    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 o

  9. The Arecibo Legacy Fast ALFA (ALFALFA) Extragalactic HI Survey

    CERN Document Server

    Haynes, Martha P

    2008-01-01

    The Arecibo Legacy Fast ALFA (ALFALFA) survey is a program aimed at obtaining a census of HI-bearing objects over a cosmologically significant volume of the local universe. When complete in ~3-4 years, it will cover 7000 square degrees of high latitude sky using the 305m telescope and the seven-beam Arecibo L-band feed array (ALFA). As of May 1, 2008, almost 60% of the required observations are complete and a catalog exists in preliminary form for 25% of the final sky area. ALFALFA is detecting about twice as many HI sources as predicted based on previously published HI mass functions and should deliver a final catalog of >25000 extragalactic HI sources. ALFALFA will detect hundreds of galaxies with HI masses less than 10**7.5 solar masses and similarly large numbers greater than 10**10.3 Msun. Its centroiding accuracy allows for the immediate identification of highly probably optical counterparts to each HI detection. Fewer than 3% of all extragalactic HI sources, and 10**9.5 Msun cannot be identified with ...

  10. An Arecibo Survey for Zeeman Splitting in OH Megamaser Galaxies

    CERN Document Server

    McBride, James

    2012-01-01

    We present the results of a comprehensive survey using the Arecibo Observatory for Zeeman splitting of OH lines in OH megamasers (OHMs). A total of seventy-seven sources were observed with the Arecibo telescope. Of these, maser emission could not be detected for eight sources, and two sources were only ambiguously detected. Another twenty-seven sources were detected at low signal-to-noise ratios or with interference that prevented placing any useful limits on the presence of magnetic fields. In twenty-six sources, it was possible to place upper limits on the magnitude of magnetic fields, typically between 10-30 mG. For fourteen sources, the Stokes V spectra exhibit features consistent with Zeeman splitting. Eleven of these fourteen are new detections, and the remaining three are re-detections of Stokes V detections in Robishaw et al. (2008). Among confident new detections, we derive magnetic fields associated with maser regions with magnitudes ranging from 6.1-27.6 mG. The distribution of magnetic field stren...

  11. Arecibo imaging of compact high-velocity clouds

    CERN Document Server

    Burton, W B; Chengalur, J N

    2001-01-01

    Ten isolated compact high-velocity clouds (CHVCs) of the type cataloged by Braun & Burton (1999) have been imaged with the Arecibo telescope and were found to have a nested core/halo morphology. We argue that a combination of high-resolution filled-aperture and synthesis data is crucial to determining the intrinsic properties of the CHVCs. We identify the halos as Warm Neutral Medium surrounding one or more cores in the Cool Neutral Medium phase. These halos are clearly detected and resolved by the Arecibo filled-aperture imaging, which reaches a limiting sensitivity (1 sigma) of N_H about 2x10^17 cm^-2 over the typical 70 km/s linewidth at zero intensity. The FWHM linewidth of the halo gas is found to be 25 km/s, consistent with a WNM thermal broadening within 10^4 K gas. Substantial asymmetries are found at high N_H (>10^18.5 cm^-2) levels in 60% of our sample. A high degree of reflection-symmetry is found at low N_H (<10^18.5 cm^-2) in all sources studied at these levels. The column-density profiles...

  12. Super-resolution nanofabrication with metal-ion doped hybrid material through an optical dual-beam approach

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yaoyu; Li, Xiangping; Gu, Min, E-mail: mgu@swin.edu.au [Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia)

    2014-12-29

    We apply an optical dual-beam approach to a metal-ion doped hybrid material to achieve nanofeatures beyond the optical diffraction limit. By spatially inhibiting the photoreduction and the photopolymerization, we realize a nano-line, consisting of polymer matrix and in-situ generated gold nanoparticles, with a lateral size of sub 100 nm, corresponding to a factor of 7 improvement compared to the diffraction limit. With the existence of gold nanoparticles, a plasmon enhanced super-resolution fabrication mechanism in the hybrid material is observed, which benefits in a further reduction in size of the fabricated feature. The demonstrated nanofeature in hybrid materials paves the way for realizing functional nanostructures.

  13. The Microstructure of RR1000 Nickel-Base Superalloy: The FIB-SEM Dual-Beam Approach

    Science.gov (United States)

    Croxall, S. A.; Hardy, M. C.; Stone, H. J.; Midgley, P. A.

    Nickel-base superalloys are aerospace materials that exhibit exceptional mechanical properties and corrosion resistance at very high temperatures. RR1000 is used in discs in gas turbine engines, where temperatures reach in excess of 650°C with high mechanical stresses. Study of the microstructure at the micron and sub-micron level has conventionally been undertaken using scanning electron microscope images, often meaning the underlying 3D microstructure can be inferred only with additional knowledge. Using a dual-beam workstation, we are able to interrogate directly the 3D microstructure using a serial sectioning approach. The 3D data set, typically (10µm)3 in volume, reveals microstructural detail with lateral resolution of circa 8nm and a depth resolution dictated by the slice thickness, typically 50nm. Morphological and volumetric analysis of the 3D reconstruction of RR1000 superalloy reveals microstructural details hitherto unseen.

  14. Comparison of single-beam and dual-beam laser welding of Ti-22Al-25Nb/TA15 dissimilar titanium alloys

    Science.gov (United States)

    Shen, Junqi; Li, Bo; Hu, Shengsun; Zhang, Hao; Bu, Xianzheng

    2017-08-01

    Laser beam welding (LBW) was used to join Ti-22Al-25Nb/TA15 dissimilar titanium alloys. The microstructure and mechanical properties of the welded joints under single and dual beam welding were analyzed and compared. In the mode of single laser beam, the fusion zone only consisted of B2 phase because of existence of β-phase stabilizer and rapid cooling rate of LBW. However, O phase was formed in the fusion zone while applying dual-beam laser welding due to decrease of the cooling rate. The microhardness distribution of the welded joint in dual-beam welding mode was consistent with that in single mode, but the hardness of the weld under dual laser beam was higher than that of single laser beam. In room-temperature tensile tests, the fractures all occurred in the weld, but the morphology exhibited a quasi-cleavage feature in single mode while the morphology was dimple fracture in the mode of dual laser beam. The tensile strength and elongation were both increased under dual-beam laser welding compared with those under single-beam laser welding.

  15. A dual beam study with isotopic X- and gamma-rays for in vivo lymph pool assay

    Science.gov (United States)

    Bolin, F. P.; Preuss, L. E.; Jedlenski, D. E.; Beninson, J.

    1986-01-01

    Dual beam absorptiometry utilizes differential absorption of X- and gamma rays of differing energy to determine an absorber's component ratio. This principle has been applied to diverse physical and biological problems. Our method, using the 22 and 88 keV emissions from 109Cd, resolves the lean and non-lean mammalian tissue fractions. Accuracy of 1%, and reproducibility of 1-2% is attainable in in vitro measurements. Techniques have been developed to apply this system to the more complicated applications involved in human studies. A scanning device capable of measuring limbs has been developed. Mathematical treatment provides an integrated value of lean fraction over the scanned area. Lymphedema is a painful malady in which blockage of lymph flow causes swelling and distension of the extremities. Compressive therapy is the preferred medical treatment. There has been no accurate quantitative index of the efficacy of this therapy. Our research program uses dual beam analysis as a unique quantitative measure of the lymph transport. Lymph pool change is equated to change in the lean. Five measurements are made on subjects undergoing a two week regimen of compressive therapy. These absorptiometric results are analyzed for correlation to other indices of treatment effect. Data shows a progressive decrease in the lean tissue component over the treatment period. Changes seen vary with the individual and the severity of involvement. This study showed that the largest transport rate occurs in the first treatment days. Absorptiometry accurately monitors total adipose mass, total non-adipose mass, extremely cross section, and change in lymph pooling.

  16. Pulsar Search Results from the Arecibo Remote Command Center

    Science.gov (United States)

    Rodriguez, Miguel; Stovall, Kevin; Banaszak, Shawn A.; Becker, Alison; Biwer, Christopher M.; Boehler, Keith; Caballero, Keeisi; Christy, Brian; Cohen, Stephanie; Crawford, Fronefield; Cuellar, Andres; Danford, Andrew; Percy Dartez, Louis; Day, David; Flanigan, Joseph D.; Fonrouge, Aldo; Gonzalez, Adolfo; Gustavson, Kathy; Handzo, Emma; Hinojosa, Jesus; Jenet, Fredrick A.; Kaplan, David L. A.; Lommen, Andrea N.; Longoria, Chasity; Lopez, Janine; Lunsford, Grady; Mahany, Nicolas; Martinez, Jose; Mata, Alberto; Miller, Andy; Murray, James; Pankow, Chris; Ramirez, Ivan; Reser, Jackie; Rojas, Pablo; Rohr, Matthew; Rolph, Kristina; Rose, Caitlin; Rudnik, Philip; Siemens, Xavier; Tellez, Andrea; Tillman, Nicholas; Walker, Arielle; Wells, Bradley L.; Zaldivar, Jonathan; Zermeno, Adrienne; Gbncc Consortium, Palfa Consortium, Gbtdrift Consortium, Ao327 Consortium

    2015-01-01

    This poster presents the pulsar discoveries made by students in the Arecibo Remote Command Center (ARCC) program. The ARCC program was started at the University of Texas - Brownsville (UTB) within the Center for Advanced Radio Astronomy (CARA) as a group of scientists, faculty, graduate, undergraduate, and high school students interested in astrophysics. It has since expanded to form other ARCC programs at the University of Wisconsin-Milwaukee (UWM) and Franklin and Marshall College (F&M). The students in the ARCC group control the world's largest radio telescopes to search and discover pulsars. Pulsars are exotic neutron stars that emit beams of electromagnetic radiation. ARCC students use a web application to view and rate the images of radio pulsar candidates based on their signal characteristics. To date, ARCC students have searched through thousands of candidates and have discovered 61 pulsars to date.

  17. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Spitler, L. G.; Freire, P. C. C.; Lazarus, P.; Lee, K. J. [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany); Cordes, J. M.; Chatterjee, S.; Wharton, R. S.; Brazier, A. [Department of Astronomy and Space Sciences, Cornell University, Ithaca, NY 14853 (United States); Hessels, J. W. T. [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Lorimer, D. R.; McLaughlin, M. A. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (United States); Kaspi, V. M.; Karako-Argaman, C. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Allen, B. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Jenet, F. A. [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Knispel, B., E-mail: lspitler@mpifr-bonn.mpg.de [Leibniz Universität, Hannover, D-30167 Hannover (Germany); and others

    2014-08-01

    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 Arecibo L-band Feed Array (ALFA) survey with the Arecibo Observatory with a DM = 557.4 ± 2.0 pc cm{sup –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.

  19. Lower Power Design for UHF RF CMOS Circuits Based on the Power Consumption Acuity

    Directory of Open Access Journals (Sweden)

    Niu Xiang-jie

    2014-01-01

    Full Text Available Excessive energy consumption of UHF tag is the bottleneck of energy saving in its wide range of applications. To address this issue, a lower power design for UHF RF CMOS circuits based on power consumption acuity is proposed in this paper. Through in-depth analysis of the static and dynamic power generation principle of UHF RF circuits in the work, the power consumption acuity can be calculated by using the correlation of circuit power and input vector. Subsequently, under the guide of this acuity, the UHF RF CMOS circuits with better energy saving can be designed. Furthermore, according to the performance indicators of EPC CIG2 UHF RFID in UHF identification, the corresponding circuit is designed and implemented. The test results show that the design of UHF RF circuit based on the acuity of power consumption can reduce 35%–40% power consumption.

  20. VizieR Online Data Catalog: NIBLES II. Arecibo follow-up observations (Butcher+, 2016)

    Science.gov (United States)

    Butcher, Z.; Schneider, S.; van Driel, W.; Lehnert, M.; Minchin, R.

    2016-11-01

    HI line observations of the 139 clear or marginally detected sources from the NIBLES Arecibo follow-up observations. Observations were carried out with the Arecibo L-band wideband receiver (L-wide) with the Wideband Arecibo Pulsar Processor (WAPP) correlator backend using two polarizations with a bandpass of 50MHz across 4096 frequency channels corresponding to a channel separation of approximately 2.6km/s. Spectrum files are the output files from Robert Minchin's CORMEASURE routine from the Arecibo Observatory. Data have been smoothed to approximately 18.7km/s. Velocities are heliocentric in the optical convention in units of km/s and flux density is in Janskys. (6 data files).

  1. Assessment of multipath and shadowing effects on UHF band in ...

    African Journals Online (AJOL)

    ... obstacles such as large buildings, trees, moving objects and hills are present along ... the use of empirical and semi-empirical path loss models analysis in built-up ... transmitters at UHF bands along four major routes of Osun State, Nigeria.

  2. 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...

  3. Ionosonde Studies of Field-Aligned Irregularities during High-Power HF Heating at Arecibo,

    Science.gov (United States)

    1988-02-01

    September 1981 ionospheric HF heating campaign at Arecibo have been simulated using simplified ionospheric models -’ and analytic raytracing techniques. The...R given by R = ((h )2 -(V ))/6B) NR h6B is the radar range of the oblique echoes and h ERT the virtual height of the overhead ionization measured at...However, the conditions of the Arecibo experiment are such that various simplifications can be made, including the adoption of analytic raytracing

  4. Depth-encoded dual beam phase-resolved Doppler OCT for Doppler-angle-independent flow velocity measurement

    Science.gov (United States)

    Qian, Jie; Cheng, Wei; Cao, Zhaoyuan; Chen, Xinjian; Mo, Jianhua

    2017-02-01

    Phase-resolved Doppler optical coherence tomography (PR-D-OCT) is a functional OCT imaging technique that can provide high-speed and high-resolution depth-resolved measurement on flow in biological materials. However, a common problem with conventional PR-D-OCT is that this technique often measures the flow motion projected onto the OCT beam path. In other words, it needs the projection angle to extract the absolute velocity from PR-D-OCT measurement. In this paper, we proposed a novel dual-beam PR-D-OCT method to measure absolute flow velocity without separate measurement on the projection angle. Two parallel light beams are created in sample arm and focused into the sample at two different incident angles. The images produced by these two beams are encoded to different depths in single B-scan. Then the Doppler signals picked up by the two beams together with the incident angle difference can be used to calculate the absolute velocity. We validated our approach in vitro on an artificial flow phantom with our home-built 1060 nm swept source OCT. Experimental results demonstrated that our method can provide an accurate measurement of absolute flow velocity with independency on the projection angle.

  5. A blu-ray laser diode based dual-beam interference lithography for fabrication of diffraction gratings for surface encoders

    Science.gov (United States)

    Zhu, Xiangwen; Li, Xinghui; Zhou, Qian; Wang, Xiaohao; Ni, Kai

    2016-11-01

    The paper presents a dual-beam interference lithography technology for fabrication of diffraction gratings for surface encoders by using cost-effective 405 nm blu-ray laser diodes. In this system, an amplitude division interferometer system is employed. A laser beam raying from a blu-ray laser diode is collimated and then divided into two beams by a beam splitter. These two beams are changed their propagation directions and interfere with each other. Generated interference fringes are exposed on the photoresist coated substrate. Grating line spacing d can be adjusted by changing the incident angle between these two beams. Grating width Wc that determines the measurement of the surface encoder is decided by the coherence length Lc of the laser diode and the grating line spacing d. Calculation and simulation were carried out to decide the grating width. Lc was experimentally obtained. A fabrication system was constructed to verify the feasibility of this technology. Diffraction gratings with a 2.5 micron line spacing and a 2.5 mm width was obtained.

  6. 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...

  7. 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.

  8. 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 ...

  9. 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...

  10. 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...

  11. 标签可重用的仓储管理系统UHF RFID阅读器设计%UHF RFID Reader for Warehouse Management System with Reusable Tags

    Institute of Scientific and Technical Information of China (English)

    曾炼成; 傅卓军

    2011-01-01

    UHF RFID tags provide performances such as non-optical visualization, long response distance and fast read speed. A novel warehouse management method is proposed, in which UHF RFID tag is reused and UHF RFID reader hardware and software are customized. UHF RFID reader hardware consists of Cortex-M3 core processor LPC1768, UHF RFID module, SPI Flash and TFT LCD display. Software design of UHF RFID reader is hierarchical and modular based on μC/GUI. The warehouse management UHF RFID tags being reused and the customization of UHF RFID reader reduce the cost of the system and promote the application of UHF RFID technology.%UHF RFID标签具有非光学可视阅读、感应距离远和读取速度快的特点.针对中小型仓储应用提出了UHF RFID标签可重用和UHF RFID阅读器软硬件定制的设计方案.UHF RFID阅读器硬件采用了Cortex- M3内核处理器LPC1768、UHF RFID模块读取标签、SPI Flash扩展存储和TFT LCD显示.UHF RFID阅读器软件基于μC/GUI图形组件层次化和模块化设计实现.仓储管理系统UHF RFID标签可重用和阅读器定制设计降低了系统的使用成本,促进了UHF RFID技术的广泛应用.

  12. Wind turbine clutter mitigation in coastal UHF radar.

    Science.gov (United States)

    Yang, Jing; Pan, Chao; Wang, Caijun; Jiang, Dapeng; Wen, Biyang

    2014-01-01

    Coastal UHF radar provides a unique capability to measure the sea surface dynamic parameters and detect small moving targets, by exploiting the low energy loss of electromagnetic waves propagating along the salty and good conducting ocean surface. It could compensate the blind zone of HF surface wave radar at close range and reach further distance than microwave radars. However, its performance is susceptible to wind turbines which are usually installed on the shore. The size of a wind turbine is much larger than the wavelength of radio waves at UHF band, which results in large radar cross section. Furthermore, the rotation of blades adds time-varying Doppler frequency to the clutter and makes the suppression difficult. This paper proposes a mitigation method which is based on the specific periodicity of wind turbine clutter and performed mainly in the time-frequency domain. Field experimental data of a newly developed UHF radar are used to verify this method, and the results prove its effectiveness.

  13. UHF-RFID技术在智能图书馆系统中的应用%The Intelligent Library System Based on UHF-RFID Technology

    Institute of Scientific and Technical Information of China (English)

    汪淑云

    2012-01-01

    The products of RFID has HF-RFID and UHF-RFID. With the increasing application of RFID technology, several domestic libraries have taken the lead in using the UHF-RFID technology and made highly effective exploration. This paper takes the application of the Intelligent Library System based on UHF-RFID technology in Beijing institute of petro-chemical technology as an example, studies the technological principle of UHF-RFID and its main functions, and explores the current features and existing problems, Prospects of the application, of RFID technology in library are also exhibited.%随着图书馆应用RFID技术的日益普及,国内已有多家图书馆尝试将超高频RFID技术运用到图书馆管理中,并进行了卓有成效的探索.笔者以北京石油化工学院引进使用的基于UHF-RFID技术的智能图书馆系统为例,通过对UHF-RFID技术原理和实现的几项主要功能的研究,探讨UHF-RFID技术在图书馆应用上的特点和存在的问题,展望了RFID技术在图书馆应用的前景.

  14. Read range measurements of UHF RFID systems in GTEM cell%在GTEM小室中测试UHF RFID系统读写距离

    Institute of Scientific and Technical Information of China (English)

    左中梁; 李书芳

    2011-01-01

    提出了使用GTEM小室进行UHF RFID系统读写距离的测试方法.分析了UHF RFID系统通信的受限因素是前向链路,从而根据前向链路信号的衰减推导了使用GTEM小室进行UHF RFID系统读写距离测量的公式及方法.在验证实验中分别在GTEM小室和电波暗室中测量了读写距离,并和真实的UHF RFID系统读写距离进行比较,实验结果表明提出的GTEM小室测试方法测量结果优于电波暗室中的测量结果,从而验证了公式及方法的可靠性,说明GTEM小室适合于进行UHF RFID系统的读写距离测试.%This paper presents a method of measure the read range of UHF RFID systems in GTEM cell. Firstly this paper concludes the deciding factor of read range of UHF RFID systems is the forward link. And then discuss the measure method of read range in GTEM cell. In the experiment,we measure the read range in GTEM cell and anechoic chamber,and the result in GTEM cell is in better agreement with the read range of real UHF RFID systems than the result in anechoic chamber. So, the measure method in this paper is effective and the GTEM cell is suitable for read range measure of UHF RFID systems.

  15. The possibility for collaboration of Arecibo with international S2 ad-hoc array

    Science.gov (United States)

    Molotov, I. E.; Chuprikov, A. A.; Salter, C.; Ghosh, T.

    2001-05-01

    The loan of an S2 VLBI recording terminal to Arecibo Observatory by the Space Geodynamics Laboratory, ISTS (now CRESTech), Canada, for support of the VSOP mission, opens the possibility of Arecibo participating in ground based VLBI observations. I.e. in collaboration with an international ad-hoc S2 array that has begun to operate under the Low Frequency VLBI Network (LFVN) project. LFVN arranges VLBI experiments using the telescopes in 11 countries which are equipped with S2 systems, together with the Penticton S2 correlator in Canada. A wide spectrum of baselines has been achieved, up to the largest on Earth, while the participation of Arecibo can ensure the high sensitivity of this S2 array. The first LFVN S2 observations including Arecibo were carried out at a wavelength of 18 cm on December 2, 1998, as part of INTAS98.5. This experiment with participation of three Russian antennas (Bear Lakes RT-64, Puschino RT-22 and Svetloe RT-32), Green Bank RT-43 and HartRAO RT-26 included 7 hrs of observation of weak sources on the Arecibo-Green Bank baseline. The successful processing of INTAS98.5 and two other observations (INTAS98.2 and INTAS99.4) by the Penticton correlator confirms the feasibility of this initiative (the post-processing was made at Astro Space Center, Russia). These VLBI observations may be continued with the Green Bank RT-100, Penticton RT-26 and Madrid RT-70. (The next S2 experiment is planned for October-November 2001). The recent equipping of Arecibo with a 92-cm receiver also opens new opportunities for LFVN cooperation, especially as there is a plan to also supply AlgoPark RT-46 and Penticton RT-26 in Canada with 92-cm facilities. Another field of interest for cooperation may be the radar VLBI research of the nearer planets with the S2 system recording of transmitted and reflected signals.

  16. Arecibo PALFA Survey and Einstein@Home: Binary Pulsar Discovery by Volunteer Computing

    OpenAIRE

    Knispel, B.; Lazarus, P; Allen, B.; Anderson, D; Aulbert, C.; Bhat, N; Bock, O.; Bogdanov, S.; Brazier, A.; Camilo, F.; S Chatterjee; Cordes, J.; Crawford, F; Deneva, J.; Desvignes, G.

    2011-01-01

    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 solar masses by analysis of spin period measurements. No evidence of orbita...

  17. Estimate of Precipitation from the Dual-Beam Airborne Radars in TOGA COARE. Part 1: The K-Z Relationships Derived from Stereo and Quad-Beam Analysis.

    Science.gov (United States)

    Oury, Stéphane; Testud, Jacques; Marécal, Virginie

    1999-02-01

    The recent development of dual-beam airborne Doppler weather radar offers the possibility to perform high-resolution observations of the three-dimensional air motion and precipitation fields associated with severe weather systems. However, the limited size of the onboard antennas imposes the use of high radar frequencies (e.g., X band) in order to achieve satisfactory beam resolutions. Therefore, the sampled radar reflectivity is attenuated when intercepting intense rain cells. This paper aims at developing algorithms for correcting the observed radar reflectivity for attenuation that fully exploit the dual-beam sampling strategy and the multiple aircraft operations conducted in Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Its specific contribution is twofold.Algorithm development. On the one hand, the former stereoradar analysis helps to retrieve independently the`true' (nonattenuated) radar reflectivity Z and specific attenuation K when using two radar beams from one aircraft. The algorithm is reformulated in Cartesian coordinates, which greatly improves its flexibility. And on the other hand, a new approach is developed, the quad-beam analysis, which is particularly powerful when processing the data of a two dual-beam aircraft operation focused on the same rain cells.Data analysis. An application of the stereoradar and quad-beam analysis to a TOGA COARE weather system is presented. The corrected Z and K fields are cross validated using different algorithms or datasets for the same event. The radar derived K-Z relationships are also compared with that deduced from in situ microphysical probes sampling using a scattering model. The full three-dimensional description of the Z and K fields is then used to appreciate to what extent the observed heavy rain reached the `equilibrium' described by previous authors in response to droplet coalescence and breakup.

  18. Approximating ambient D-region electron densities using dual-beam HF heating experiments at the high-frequency Active Auroral Research Program (HAARP)

    Science.gov (United States)

    Agrawal, Divya

    Dual-beam ELF/VLF wave generation experiments performed at the High-frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska are critically compared with the predictions of a newly developed ionospheric high frequency (HF) heating model that accounts for the simultaneous propagation and absorption of multiple HF beams. The dual-beam HF heating experiments presented herein consist of two HF beams transmitting simultaneously: one amplitude modulated (AM) HF beam modulates the conductivity of the lower ionosphere in the extremely low frequency (ELF, 30 Hz to 3 kHz) and/or very low frequency (VLF, 3 kHz to 30 kHz) band while a second HF beam broadcasts a continuous waveform (CW) signal, modifying the efficiency of ELF/VLF conductivity modulation and thereby the efficiency of ELF/VLF wave generation. Ground-based experimental observations are used together with the predictions of the theoretical model to identify the property of the received ELF/VLF wave that is most sensitive to the effects of multi-beam HF heating, and that property is determined to be the ELF/VLF signal magnitude. The dependence of the generated ELF/VLF wave magnitude on several HF transmission parameters (HF power, HF frequency, and modulation waveform) is then experimentally measured and analyzed within the context of the multi-beam HF heating model. For all cases studied, the received ELF/VLF wave magnitude as a function of transmission parameter is analyzed to identify the dependence on the ambient D-region electron density (Ne) and/or electron temperature ( Te), in turn identifying the HF transmission parameters that provide significant independent information regarding the ambient conditions of the D-region ionosphere. A theoretical analysis is performed to determine the conditions under which the effects of Ne and Te can be decoupled, and the results of this analysis are applied to identify an electron density profile that can reproduce the unusually high level of ELF

  19. The Effects of GSM Mobile Phone on the UHF RFID Read Results%GSM移动终端对UHF RFID读取效果的影响

    Institute of Scientific and Technical Information of China (English)

    邵华东; 李扬; 薛峰

    2009-01-01

    近年来,UHF RFID技术的发展与应用及EPC G2电子标签的发展给人们生产生活带来了方便.但是由于 GSM的频段与UHF RFID频段很接近,因此探讨移动通信对UHF RFID读取效果的影响显得日益重要.文章介绍了我国UHF RFID与GSM频段的划分、电子标签的接收功率与反射功率、测试模型、测试结果的分析,为两者相距很近工作时所面临的干扰提出了合理的对策与建议.

  20. Improved Absolute Radiometric Calibration of a UHF Airborne Radar

    Science.gov (United States)

    Chapin, Elaine; Hawkins, Brian P.; Harcke, Leif; Hensley, Scott; Lou, Yunling; Michel, Thierry R.; Moreira, Laila; Muellerschoen, Ronald J.; Shimada, Joanne G.; Tham, Kean W.; hide

    2015-01-01

    The AirMOSS airborne SAR operates at UHF and produces fully polarimetric imagery. The AirMOSS radar data are used to produce Root Zone Soil Moisture (RZSM) depth profiles. The absolute radiometric accuracy of the imagery, ideally of better than 0.5 dB, is key to retrieving RZSM, especially in wet soils where the backscatter as a function of soil moisture function tends to flatten out. In this paper we assess the absolute radiometric uncertainty in previously delivered data, describe a method to utilize Built In Test (BIT) data to improve the radiometric calibration, and evaluate the improvement from applying the method.

  1. RFID antenna design for circular polarization in UHF band

    Science.gov (United States)

    Shahid, Hamza; Khan, Muhammad Talal Ali; Tayyab, Umais; Irshad, Usama Bin; Alkhazraji, Emad; Javaid, Muhammad Sharjeel

    2017-05-01

    A miniature half cross dipole antenna for defense and aerospace RFID applications in UHF band is presented. The dipole printed line arms are half crossed shape on top of dielectric substrate backed by reactive impedance surface. The antenna fed by a coaxial cable at the gap separating the dipole arms. Our design is intended to work at 2.42 GHz for RFID readers. The radiation pattern obtained has HPBW of 112, return loss of 22.24 dB and 90 MHz bandwidth.

  2. Diseño de antenas UHF para aplicaciones RFID

    OpenAIRE

    Hernández Ripoll, José Vicente

    2009-01-01

    Aquest projecte es basa en l'estudi, disseny i avaluació d'antenes per a aplicacions RFID a la banda UHF. Les etiquetes RFID estan compostes per un xip i una antena que han de presentar una bona adaptació per a aconseguir màxima transferència de potència. Els dos objectius principals en els diferents fases de disseny de cada antena han estat optimitzar les seves dimensions, i incrementar l'ample de banda. Este proyecto se basa en el estudio, diseño y evaluación de antenas para aplicaciones...

  3. 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

  4. Dual beam Doppler FD-OCT system with integrated Dynamic Vessel Analyzer and rotatable beams to measure total retinal blood flow

    Science.gov (United States)

    Doblhoff-Dier, Veronika; Werkmeister, René M.; Gröschl, Martin; Schmetterer, Leopold

    2014-03-01

    We present a method capable of measuring the total retinal blood flow in arteries and veins based on dual beam Fourierdomain Doppler optical coherence tomography (OCT) in combination with a fundus camera based Dynamic Vessel Analyzer. Incorporating a Dynamic vessel analyzer into the system not only gives a live image of the fundus - it also allows determining the vessels' diameter precisely during the OCT measurement, which is necessary for the determination of the blood flow. While dual beam systems with fixed detection plane allow only vessels with certain orientations to be measured, the detection plane of our system can be rotated by 90°. This ensures that the blood's velocity can be measured in all vessels around the optic nerve head. The results of the total blood flow measurements are in the same range as previously published data. Additionally, the high degree of conformity between the measured venous and arterial flow corroborated the system's validity. For larger vessels, the logarithmic values of vessel diameter and blood flow were found to be related linearly with a regression coefficient of around 3, which is in accordance with Murray's law. For smaller vessels (diameter below 60 μm), the values diverge from the linear dependence. The high sensitivity and the good agreement with published data suggest a high potential for examining the retinal blood flow in patients with ocular diseases.

  5. Identification of surgical instruments using UHF-RFID technology

    Directory of Open Access Journals (Sweden)

    Bourouah Mohamed

    2015-09-01

    Full Text Available The paper presents research, development and advantage of Radio Frequency IDentification (RFID technology based system for medical instrument management and safe usage. The system is developed for two scenarios. In the first scenario, a Ultra High Frequency (UHF is used and the UHF–interrogator system with UHF-antennas is constructed to work as conveyor-belt and instruments are placed between two antennas. Second scenario, suitable for the operating rooms, includes four antennas, placed under the table with instruments, system’s phase shifter, inserted between the antenna and reader in order to reduce the effect of dead spots, caused by the electromagnetic reflections. High reliable identification rate is achieved by synchronizing phase shifters with particular interrogator. The system is software calibrated and can be re-calibrated at run-time to achieve high efficiency of power transmission to the antenna and in order to enable the receiver to decode the tag signals. With currently on the market available RFID tags and previously mentioned technology approaches, detection rate of 87.5% can be achieved.

  6. VDMOS transistors for power amplifier in UHF band

    Science.gov (United States)

    Kassmi, Kamal

    Modeling of power VDMOSFET transistors working in the UHF band is considered. VDMOSFET power structures suited to mobile radiotelephony power amplification are described. A nonlinear physical model suitable for all working regimes is developed. The elements of this model only depend on physical and technological data and bias voltages of the device. A reduced model compatible with SPICE (Simulation Program with Integrated Circuit Emphasis) is presented. A first comparison between measured and computed characteristics is presented under DC switching and small signal conditions. A methodology for the study and design of radio frequency power amplifiers in a nonlinear regime is described. The performance of these devices in terms of power gain, output power, efficiency, linearity and the drain bias influence as well as third order Intermodulation Distortion (IMD3) are considered. It is shown that IMD and power gain performances are controlled by DC output characteristics in the ohmic zone. Practical conclusions with respect to the intrinsic qualities and drawbacks of these products for UHF power amplification are drawn.

  7. 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.

  8. Performance Analysis of Multi-Antenna UHF RFID System%多天线 UHF RFID 系统的性能分析

    Institute of Scientific and Technical Information of China (English)

    李巨虎; 张海燕

    2015-01-01

    超高频(UHF)射频识别(RFID)系统的性能受到多径信道的制约,为提高UHF RFID系统的可靠性,文中针对前向信道和后向信道都为莱斯分布的UHF RFID系统,给出了最大比合并( MRC)准则下系统信噪比的概率分布,导出了系统中断概率和误码率的理论表达式,并开发了多天线UHF RFID读写器的原型机,通过数值仿真和实际测试考察接收天线数、莱斯因子对系统性能的影响。实验结果表明,多天线技术能够有效地提高UHF RFID系统的性能,并且接收天线越多,系统的中断概率和误码率越低。%The performances of UHF ( Ultra-High Frequency) RFID ( Radio Frequency Identification) systems are affected by multi-path channels.In order to improve the reliability of UHF RFID systems, this paper gives the probability distribution of SNR ( Signal-to-Noise Ratio) under the MRC ( Maximal Ratio Combining) combiner for the UHF RFID system with Rician distribution in both forward and backward channels, and presents the theoretical descriptions of both outage probability and bit error rate.Then, a prototype of multi-antenna UHF RFID reader is developed, and the system performance affected by receiving antenna number and Rician factor is investigated through numerical simulation and practical test.Experimental results show that multi-antenna technology improves the performance of UHF RFID systems effectively, and that the outage probability and bit error rate of UHF RFID systems both decrease as the receiving antenna number increases.

  9. UHF RFID系统相位噪声的研究与仿真%Study and Simulation of Phase Noise for UHF RFID System

    Institute of Scientific and Technical Information of China (English)

    张俊; 何怡刚; 侯周国; 代扬

    2009-01-01

    This paper introduces an analysis method of phase noise requirements on a local oscillator for a UHF Radio Frequency Identification (RFID) system. In general case, phase noise requirements are derived considering a reciprocal mixing with an interference signal. In UHF RFID system, the same oscillator is used for the transmitted signal and the Local Oscillator(LO), range correlation phenomenon effects the phase noise requirements. This paper derives new phase noise equation considering the range correlation effect on the RFID system and a simulation is done. Simulation results for UHF RFID system show that range correlation effect is the important factor in RFID system design.%介绍一种UHF RFID系统席:振相位噪声性能分析的方法.在一般情况下,相位噪卢是频埤c源信号与干扰信号的相互混频.在UHFRFID系统中发射信号与本振信号使用的是相同的振荡器,距离相关现象会影响相位噪声性能的指标要求.在考虑到距离相关影响的前提下重新得到RFID系统的新的相位噪卢方程并进行仿真,仿真结果表明距离相关是UHF RFID系统没计中的重要囚素.

  10. 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.

  11. SETHI@Berkeley- A Piggyback 21-cm Sky Survey at Arecibo

    CERN Document Server

    Korpela, E J; Heien, E; Heiles, C; Werthimer, D; Korpela, Eric J.; Demorest, Paul; Heien, Eric; Heiles, Carl; Werthimer, Dan

    2001-01-01

    SETI@home observes a 2.5 MHz bandwidth centered on 1420 MHz near the 21-cm line using a short line feed at Arecibo which provides a 6' beam. This feed sits on Carriage House 1. During normal astronomical observations with the new Gregorian dome the feed scans across the sky at twice the sidereal rate. We are using the SETI@home receiver to obtain about 4.4x10^6 HI spectra per year with integration time of 5 seconds per spectrum. We have accumulated 2.6 years of data covering most of the sky observable from Arecibo. This survey has much better angular resolution than previous single dish surveys and better sensitivity than existing or planned interferometric surveys.

  12. A Numerical Estimation of a RFID Reader Field and SAR inside a Blood Bag at UHF

    Directory of Open Access Journals (Sweden)

    Alessandro Fanti

    2016-11-01

    Full Text Available In this paper, the effects of UHF electromagnetic fields produced by a RFID reader on a blood bag are evaluated numerically in several configurations. The results of the simulation, field level and distribution, specific absorption rate (SAR, and heating time show that an exposure to a typical reader field leads to a temperature increase smaller than 0.1 C and to a SAR smaller than 1 W/kg. As a consequence, no adverse biological effects occur during a typical UHF RFID reading cycle on a blood bag. Therefore, the blood contained in a bag traced using UHF-RFID is as safe as those traced using barcodes. The proposed analysis supports the use of UHF RFID in the blood transfusion supply chain.

  13. Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags: e0132530

    National Research Council Canada - National Science Library

    Md Rokunuzzaman; Mohammad Tariqul Islam; Haslina Arshad; Mandeep Jit Singh; Norbahiah Misran

    2015-01-01

      This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network...

  14. Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags

    National Research Council Canada - National Science Library

    Rokunuzzaman, Md; Islam, Mohammad Tariqul; Arshad, Haslina; Jit Singh, Mandeep; Misran, Norbahiah

    2015-01-01

    This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network...

  15. Use of Multibeam and Dual-Beam Sonar Systems to Observe Cavitating Flow Produced by Ferryboats: In a Marine Renewable Energy Perspective

    Directory of Open Access Journals (Sweden)

    Francisco Francisco

    2017-07-01

    Full Text Available With the prospect to deploy hydrokinetic energy converters in areas with heavy boat traffic, a study was conducted to observe and assess the depth range of cavitating flow produced by ferryboats in narrow channels. This study was conducted in the vicinity of Finnhamn Island in Stockholm Archipelago. The objectives of the survey were to assess whether the sonar systems were able to observe and measure the depth of what can be cavitating flow (in a form of convected cloud cavitation produced by one specific type of ferryboats frequently operating in that route, as well as investigate if the cavitating flow within the wake would propagate deep enough to disturb the water column underneath the surface. A multibeam and a dual-beam sonar systems were used as measurement instruments. The hypothesis was that strong and deep wake can disturb the optimal operation of a hydrokinetic energy converter, therefore causing damages to its rotors and hydrofoils. The results showed that both sonar system could detect cavitating flows including its strength, part of the geometrical shape and propagation depth. Moreover, the boat with a propeller thruster produced cavitating flow with an intense core reaching 4 m of depth while lasting approximately 90 s. The ferry with waterjet thruster produced a less intense cavitating flow; the core reached depths of approximately 6 m, and lasted about 90 s. From this study, it was concluded that multibeam and dual-beam sonar systems with operating frequencies higher than 200 kHz were able to detect cavitating flows in real conditions, as long as they are properly deployed and the data properly analyzed.

  16. A 20 cm Search for Pulsars in Globular Clusters with Arecibo and the GBT

    CERN Document Server

    Hessels, J W T; Freire, P C C; Kaspi, V M; Lorimer, D R; Ransom, S M; Stairs, I H; Backer, Donald C.; Freire, Paulo C.C.; Hessels, Jason W.T.; Kaspi, Victoria M.; Lorimer, Duncan R.; Ransom, Scott M.; Stairs, Ingrid H.

    2004-01-01

    We are conducting deep searches for radio pulsations at L-band (~ 20cm) towards more than 30 globular clusters using the 305m Arecibo telescope in Puerto Rico and the 100m Green Bank Telescope in West Virginia. With roughly three quarters of our search data analyzed, we have discovered 12 new millisecond pulsars, 11 of which are in binary systems, and at least three of which eclipse. We have timing solutions for several of these systems.

  17. The Arecibo 430-MHz Intermediate Galactic Latitude Survey: Discovery of Nine Radio Pulsars

    CERN Document Server

    Navarro, J; Freire, P C; Navarro, Jose; Anderson, Stuart; Freire, Paulo C.

    2003-01-01

    We have used the Arecibo Radio Telescope to search for millisecond pulsars in two intermediate Galactic latitude regions (7 deg < | b | < 20 deg) accessible to this telescope. For these latitudes the useful millisecond pulsar search volume achieved by Arecibo's 430-MHz beam is predicted to be maximal. Searching a total of 130 square degrees, we have discovered nine new pulsars and detected four previously known objects. We compare the results of this survey with those of other 430-MHz surveys carried out at Arecibo and of an intermediate latitude survey made at Parkes that included part of our search area; the latter independently found two of the nine pulsars we have discovered. At least six of our discoveries are isolated pulsars with ages between 5 and 300 Myr; one of these, PSR J1819+1305, exhibits very marked and periodic nulling. We have also found a recycled pulsar, PSR J2016+1948. With a rotational period of 65 ms, this is a member of a binary system with a 635-day orbital period. We discuss som...

  18. 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.

  19. The GALEX Arecibo SDSS Survey. VI. Second Data Release and Updated Gas Fraction Scaling Relations

    CERN Document Server

    Catinella, Barbara; Kauffmann, Guinevere; Fabello, Silvia; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Cooper, Andrew P; Wang, Jing

    2012-01-01

    We present the second data release from the GALEX Arecibo SDSS Survey (GASS), an ongoing large Arecibo program to measure the HI properties for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025Arecibo observations of 240 galaxies, and marks the 50% of the complete survey. We present catalogs of the HI, optical and ultraviolet parameters for these galaxies, and their HI-line profiles. Having more than doubled the size of the sample since the first data release, we also revisit the main scaling relations of the HI mass fraction with galaxy stellar mass, stellar mass surface density, concentration index, and NUV-r color, as well as the gas fraction plane introduced in our earli...

  20. 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...

  1. The Arecibo Environment Galaxy Survey: The NGC 2577/UGC 4375-galaxy pair

    Science.gov (United States)

    Iguina, Ashley Ann; Minchin, Robert F.

    2017-01-01

    We searched for and catalogued galaxy candidates in an area of 5 square degrees around the NGC 2577/UGC 4375-galaxy pair via the 21-cm emission of the neutral hydrogen gas emitted by the candidates' interstellar media. The data were taken as a part of the Arecibo Galaxy Environment Survey (AGES) and consist of a data cube with the dimensions right ascension, declination, and the recessional velocity of the 21-cm line. We used the FITS viewer FRELLED to assist in visually extracting sources. We have cross identified the galaxy candidates with optical counterparts via the NASA Extragalactic Database and data from the Sloan Digital Sky Survey. We made a total of 49 HI detections in the vicinity of the galaxy pair. We did not detect the S0 galaxy, NGC 2577, but we did detect the SB galaxy, UGC 4375, and four galaxies in the region around the galaxy pair at ~2000 km/s. We detected another overdensity at 4000 km/s. Additionally, an HI detection appears in our local neighborhood at 426 km/s. The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation and in alliance with Ana G. Méndez-Universidad Metropolitana, and the Universities Space Research Association. The Arecibo Observatory REU program is funded under grant AST-1559849 to Universidad Metropolitana.

  2. The Arecibo Legacy Fast ALFA Survey: II. Results of Precursor Observations

    CERN Document Server

    Giovanelli, R; Kent, B R; Perillat, P; Catinella, B; Hoffman, G L; Momjian, E; Rosenberg, J L; Saintonge, A; Spekkens, K; Stierwalt, S; Brosch, N; Masters, K L; Springob, C M; Karachentsev, I D; Karachentseva, V E; Koopmann, R A; Müller, E; Van Driel, W; Van Zee, L; Giovanelli, Riccardo; Haynes, Martha P.; Kent, Brian R.; Perillat, Philip; Catinella, Barbara; Momjian, Emmanuel; Rosenberg, Jessica L.; Saintonge, Amelie; Spekkens, Kristine; Stierwalt, Sabrina; Brosch, Noah; Masters, Karen L.; Springob, Christopher M.; Karachentsev, Igor D.; Karachentseva, Valentina E.; Koopmann, Rebecca A.; Muller, Erik; Driel, Wim van; Zee, Liese van

    2005-01-01

    In preparation for the full Arecibo Legacy Fast ALFA extragalactic HI survey, precursor observations were carried out in Aug--Sep 2004 with the 7-beam Arecibo L-band feed array (ALFA) receiver system and the WAPP spectral processors. While these observations were geared mainly at testing and debugging survey strategy, hardware and software, approximately 36 hours of telescope time yielded science--quality data. From those observations, an initial list of 730 tentative detections of varying degree of reliability was extracted. Ninety--eight high signal-to-noise candidates were deemed to be bona fide HI line detections. To test our ability to discriminate cosmic signals from RFI and noise, 165 candidates ranging in reliability likelihood were re--observed with the single beam L--band wide system at Arecibo in Jan--Feb 2005. Of those, 41% were confirmed as real. We present the results of both the ALFA and single beam observations for the sample of 166 confirmed HI sources, as well as our assessment of their opti...

  3. The NSF Undergraduate ALFALFA Team: Partnering with Arecibo Observatory to Offer Undergraduate and Faculty Extragalactic Radio Astronomy Research Opportunities

    Science.gov (United States)

    Ribaudo, Joseph; Koopmann, Rebecca A.; Haynes, Martha P.; Balonek, Thomas J.; Cannon, John M.; Coble, Kimberly A.; Craig, David W.; Denn, Grant R.; Durbala, Adriana; Finn, Rose; Hallenbeck, Gregory L.; Hoffman, G. Lyle; Lebron, Mayra E.; Miller, Brendan P.; Crone-Odekon, Mary; O'Donoghue, Aileen A.; Olowin, Ronald Paul; Pantoja, Carmen; Pisano, Daniel J.; Rosenberg, Jessica L.; Troischt, Parker; Venkatesan, Aparna; Wilcots, Eric M.; ALFALFA Team

    2017-01-01

    The NSF-sponsored Undergraduate ALFALFA (Arecibo Legacy Fast ALFA) Team (UAT) is a consortium of 20 institutions across the US and Puerto Rico, founded to promote undergraduate research and faculty development within the extragalactic ALFALFA HI blind survey project and follow-up programs. The objective of the UAT is to provide opportunities for its members to develop expertise in the technical aspects of observational radio spectroscopy, its associated data analysis, and the motivating science. Partnering with Arecibo Observatory, the UAT has worked with more than 280 undergraduates and 26 faculty to date, offering 8 workshops onsite at Arecibo (148 undergraduates), observing runs at Arecibo (69 undergraduates), remote observing runs on campus, undergraduate research projects based on Arecibo science (120 academic year and 185 summer projects), and presentation of results at national meetings such as the AAS (at AAS229: Ball et al., Collova et al., Davis et al., Miazzo et al., Ruvolo et al, Singer et al., Cannon et al., Craig et al., Koopmann et al., O'Donoghue et al.). 40% of the students and 45% of the faculty participants have been women and members of underrepresented groups. More than 90% of student alumni are attending graduate school and/or pursuing a career in STEM. 42% of those pursuing graduate degrees in Physics or Astronomy are women.In this presentation, we summarize the UAT program and the current research efforts of UAT members based on Arecibo science, including multiwavelength followup observations of ALFALFA sources, the UAT Collaborative Groups Project, the Survey of HI in Extremely Low-mass Dwarfs (SHIELD), and the Arecibo Pisces-Perseus Supercluster Survey (APPSS). This work has been supported by NSF grants AST-0724918/0902211, AST-075267/0903394, AST-0725380, AST-121105, and AST-1637339.

  4. Design of a miniature UHF RFID reader&writer module%超小型UHF RFID读写模块的设计

    Institute of Scientific and Technical Information of China (English)

    李沈飞; 文光俊; 黄丽

    2011-01-01

    Based on the core module PR9000,which is the radio frequency transceiver chip of the company PHYCHIPS,combining the power management module,has developed a UHF RFID readerwriter module realizing miniature.Under the frequency range from 840 to 960MHz,receiveing sensitivity under-70dBm,transmit power-13 to 10dBm,which can be adjusted by software,power consumption under 5W.UHF RFID readerwrite module has the advantage of small size,high sensitivity and low power consumption,which can be embedded to mobile phone,printer,etc.has the extensive application domain.%采用PHYCHIPS公司的UHF频段前端收发芯片PR9000作为核心芯片,并结合电源管理模块,设计实现了一款超小型UHF RFID读写模块,在工作频率840~960 MHz范围内,接收灵敏度小于-70 dBm,发射功率-13-10dBm可调,功耗小于5 W。UHF RFID读写模块具有尺寸小、灵敏度高和低功耗的优点,可嵌入手机、打印机等移动终端,具有广泛的应用领域。

  5. UHF Relay Antenna Measurements on Phoenix Mars Lander Mockup

    Science.gov (United States)

    Ilott, Peter; Harrel, Jefferson; Arnold, Bradford; Bliznyuk, Natalia; Nielsen, Rick; Dawson, David; McGee, Jodi

    2006-01-01

    The Phoenix Lander, a NASA Discovery mission which lands on Mars in the spring of 2008, will rely entirely on UHF relay links between it and Mars orbiting assets, (Odyssey and Mars Reconnaissance Orbiter (MRO)), to communicate with the Earth. As with the Mars Exploration Rover (MER) relay system, non directional antennas will be used to provide roughly emispherical coverage of the Martian sky. Phoenix lander deck object pattern interference and obscuration are significant, and needed to be quantified to answer system level design and operations questions. This paper describes the measurement campaign carried out at the SPAWAR (Space and Naval Warfare Research) Systems Center San Diego (SSC-SD) hemispherical antenna range, using a Phoenix deck mockup and engineering model antennas. One goal of the measurements was to evaluate two analysis tools, the time domain CST, and the moment method WIPL-D software packages. These would subsequently be used to provide pattern analysis for configurations that would be difficult and expensive to model and test on Earth.

  6. 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.

  7. Generating lunar bistatic SAR images using Arecibo and Mini-RF

    Science.gov (United States)

    Wahl, Daniel E.; Yocky, David A.; Bussey, Ben; Jakowatz, Charles V., Jr.

    2012-05-01

    We have employed the Arecibo Observatory Planetary Radar (AO) transmitter and the Mini-RF radar onboard NASA's Lunar Reconnaissance Orbiter (LRO) as a receiver to collect bistatic data of the lunar surface. In this paper, we demonstrate the ability to form bistatic polarimetric imagery with spatial resolution on the order of 50m, and to create polarimetric maps that could potentially reveal the presence of ice in lunar permanently shadowed craters. We discuss the details of the signal processing techniques that are required to allow these products to be formed.

  8. 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

  9. 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…

  10. 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…

  11. Time-resolved thermal lens spectroscopy with a single-pulsed laser excitation beam: an analytical model for dual-beam mode-mismatched experiments.

    Science.gov (United States)

    Sabaeian, Mohammad; Rezaei, Hamidreza; Ghalambor-Dezfouli, Abdolmohammad

    2017-02-01

    Pulsed laser beam excitations are more commonly used in thermal lens spectroscopy (TLS) than continuous-wave (CW) ones, because CW excitations limit the measurement to linear absorption processes [J. Opt. A5, 256 (2003)]. In this work, we present a new and full analytical model for a single-pulsed laser excitation dual-beam mode-mismatched TLS for low absorption solid-state and liquid samples. Our model has been based on a new solution of time-dependent heat equation for a finite-radius cylindrical sample exposed to a single-pulsed excitation laser beam. For low absorbent samples, unlike previous models, all aberration terms associated in the thermal lens were taken into account in Fresnel integration. Besides, the model provides a full analytical mathematical expression for the temperature rise, normalized signal intensity, and Z-scan photothermal lens signal. The model was confirmed with experimental data of distilled deionized water with excellent agreement. Therefore, the model allows us to extract thermo-optical properties of samples in an analytical and more accurate way.

  12. Femtosecond time-resolved X-ray absorption spectroscopy of liquid using a hard X-ray free electron laser in a dual-beam dispersive detection method.

    Science.gov (United States)

    Obara, Yuki; Katayama, Tetsuo; Ogi, Yoshihiro; Suzuki, Takayuki; Kurahashi, Naoya; Karashima, Shutaro; Chiba, Yuhei; Isokawa, Yusuke; Togashi, Tadashi; Inubushi, Yuichi; Yabashi, Makina; Suzuki, Toshinori; Misawa, Kazuhiko

    2014-01-13

    We present femtosecond time-resolved X-ray absorption spectroscopy of aqueous solution using a hard x-ray free electron laser (SACLA) and a synchronized Ti:sapphire laser. The instrumental response time is 200 fs, and the repetition rate of measurement is 10 Hz. A cylindrical liquid beam 100 μm in diameter of aqueous ammonium iron(III) oxalate solution is photoexcited at 400 nm, and the transient X-ray absorption spectra are measured in the K-edge region of iron, 7.10 - 7.26 keV, using a dual X-ray beam dispersive detection method. Each of the dual beams has the pulse energy of 1.4 μJ, and pump-induced absorbance change on the order of 10(-3) is successfully detected. The photoexcited iron complex exhibits a red shifted iron K-edge with the appearance time constant of 260 fs. The X-ray absorption difference spectra, with and without the pump pulses, are independent of time delay after 1.5 ps up to 100 ps, indicating that the photoexcited species is long-lived.

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

    Institute of Scientific and Technical Information of China (English)

    Fan Bo; Dai Yujie; Zhang Xiaoxing; LV Yingjie

    2009-01-01

    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 ap-proximation 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.

  14. Experimental Study on Inkjet-Printed Passive UHF RFID Tags on Versatile Paper-Based Substrates

    Directory of Open Access Journals (Sweden)

    Han He

    2016-01-01

    Full Text Available We present the possibilities and challenges of passive UHF RFID tag antennas manufactured by inkjet printing silver nanoparticle ink on versatile paper-based substrates. The most efficient manufacturing parameters, such as the pattern resolution, were determined and the optimal number of printed layers was evaluated for each substrate material. Next, inkjet-printed passive UHF RFID tags were fabricated on each substrate with the optimized parameters and number of layers. According to our measurements, the tags on different paper substrates showed peak read ranges of 4–6.5 meters and the tags on different cardboard substrates exhibited peak read ranges of 2–6 meters. Based on their wireless performance, these inkjet-printed paper-based passive UHF RFID tags are sufficient for many future wireless applications and comparable to tags fabricated on more traditional substrates, such as polyimide.

  15. UHF wearable battery free sensor module for activity and falling detection.

    Science.gov (United States)

    Nam Trung Dang; Thang Viet Tran; Wan-Young Chung

    2016-08-01

    Falling is one of the most serious medical and social problems in aging population. Therefore taking care of the elderly by detecting activity and falling for preventing and mitigating the injuries caused by falls needs to be concerned. This study proposes a wearable, wireless, battery free ultra-high frequency (UHF) smart sensor tag module for falling and activity detection. The proposed tag is powered by UHF RF wave from reader and read by a standard UHF Electronic Product Code (EPC) Class-1 Generation-2 reader. The battery free sensor module could improve the wearability of the wireless device. The combination of accelerometer signal and received signal strength indication (RSSI) from a reader in the passive smart sensor tag detect the activity and falling of the elderly very successfully. The fabricated smart sensor tag module has an operating range of up to 2.5m and conducting in real-time activity and falling detection.

  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. SIX NEW MILLISECOND PULSARS FROM ARECIBO SEARCHES OF FERMI GAMMA-RAY SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Cromartie, H. T. [Department of Astronomy, University of Virginia, Charlottesville, VA 22903 (United States); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Kerr, M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping, NSW 1710 (Australia); Deneva, J. S.; Ray, P. S.; Wood, K. S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903 (United States); Ferrara, E. C. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Michelson, P. F., E-mail: thankful@virginia.edu [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2016-03-01

    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) four 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 MSP candidates, and will be re-searched.

  18. Pulse-level interference and meteor processing of Arecibo ISR data

    Science.gov (United States)

    Wen, C.-H.; Briczinski, S. J.; Livneh, D. J.; Doherty, J. F.; Mathews, J. D.

    2007-07-01

    We introduce a simple but effective order statistics filter for the pulse-level interference and meteor processing of Arecibo ionosphere observation data. Using this filter and the techniques introduced by Wen et al. [2005. Adaptive filtering for the separation of incoherent scatter and meteor signals for Arecibo Observation Data. Journal of Atmospheric and Solar-Terrestrial Physics 67, 1190 1195] we effectively remove/separate the unwanted signals, such as impulsive interference and meteor returns, encountered during incoherent scatter radar (ISR) observations of the ionosphere. We further analyze the separated signals to obtain uniquely “cleaned” incoherent scatter power data and scientifically valuable meteor parameters. We present the processed incoherent scatter results from 22/23 March 2004 observations and the altitude and the speed distributions of the separated meteor signals. The nighttime photochemical E-region is clearly revealed for the first time as a result of meteor and interference removal. Additionally, these results reveal the first major bias in large aperture radar meteor headecho results—the meteor speed distribution is flattened by the absence of at least 50% of the events with duration less than 10 ms revealed by meteor-specific observations. Meteor data derived from standard incoherent scatter data always displays this bias.

  19. 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 ...

  20. SETIBURST: A Robotic, Commensal, Realtime Multi-science Backend for the Arecibo Telescope

    Science.gov (United States)

    Chennamangalam, Jayanth; MacMahon, David; Cobb, Jeff; Karastergiou, Aris; Siemion, Andrew P. V.; Rajwade, Kaustubh; Armour, Wes; Gajjar, Vishal; Lorimer, Duncan R.; McLaughlin, Maura A.; Werthimer, Dan; Williams, Christopher

    2017-02-01

    Radio astronomy has traditionally depended on observatories allocating time to observers for exclusive use of their telescopes. The disadvantage of this scheme is that the data thus collected is rarely used for other astronomy applications, and in many cases, is unsuitable. For example, properly calibrated pulsar search data can, with some reduction, be used for spectral line surveys. A backend that supports plugging in multiple applications to a telescope to perform commensal data analysis will vastly increase the science throughput of the facility. In this paper, we present “SETIBURST,” a robotic, commensal, realtime multi-science backend for the 305 m Arecibo Telescope. The system uses the 1.4 GHz, seven-beam Arecibo L-band Feed Array (ALFA) receiver whenever it is operated. SETIBURST currently supports two applications: SERENDIP VI, a SETI spectrometer that is conducting a search for signs of technological life, and ALFABURST, a fast transient search system that is conducting a survey of fast radio bursts (FRBs). Based on the FRB event rate and the expected usage of ALFA, we expect 0-5 FRB detections over the coming year. SETIBURST also provides the option of plugging in more applications. We outline the motivation for our instrumentation scheme and the scientific motivation of the two surveys, along with their descriptions and related discussions.

  1. 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...

  2. 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...

  3. Arecibo PALFA Survey and Einstein@Home: Binary Pulsar Discovery by Volunteer Computing

    Science.gov (United States)

    Knispel, B.; Lazarus, P.; Allen, B.; Anderson, D.; Aulbert, C.; Bhat, N. D. R.; Bock, O.; Bogdanov, S.; Brazier, A.; Camilo, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Desvignes, G.; Fehrmann, H.; Freire, P. C. C.; Hammer, D.; Hessels, J. W. T.; Jenet, F. A.; Kaspi, V. M.; Kramer, M.; van Leeuwen, J.; Lorimer, D. R.; Lyne, A. G.; Machenschalk, B.; McLaughlin, M. A.; Messenger, C.; Nice, D. J.; Papa, M. A.; Pletsch, H. J.; Prix, R.; Ransom, S. M.; Siemens, X.; Stairs, I. H.; Stappers, B. W.; Stovall, K.; Venkataraman, A.

    2011-05-01

    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 M sun by analysis of spin period measurements. No evidence of orbital eccentricity is apparent; we set a 2σ upper limit e <~ 1.7 × 10-3. The orbital parameters suggest a massive white dwarf companion with a minimum mass of 0.95 M sun, assuming a pulsar mass of 1.4 M sun. 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.

  4. Arecibo PALFA Survey and Einstein@Home: Binary Pulsar Discovery by Volunteer Computing

    CERN Document Server

    Knispel, B; Allen, B; Anderson, D; Aulbert, C; Bhat, N D R; Bock, O; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J S; Desvignes, G; Fehrmann, H; Freire, P C C; Hammer, D; Hessels, J W T; Jenet, F A; Kaspi, V M; Kramer, M; van Leeuwen, J; Lorimer, D R; Lyne, A G; Machenschalk, B; McLaughlin, M A; Messenger, C; Nice, D J; Papa, M A; Pletsch, H J; Prix, R; Ransom, S M; Siemens, X; Stairs, I H; Stappers, B W; Stovall, K; Venkataraman, A

    2011-01-01

    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 solar masses by analysis of spin period measurements. No evidence of orbital eccentricity is apparent; we set a 2-sigma upper limit e < 1.7e-3. The orbital parameters suggest a massive white dwarf companion with a minimum mass of 0.95 solar masses, assuming a pulsar mass of 1.4 solar masses. 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.

  5. 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....

  6. Hash Function Construction Algorithm Applying to UHF RFID Authentication%适用于UHF RFID认证协议的Hash函数构造算法

    Institute of Scientific and Technical Information of China (English)

    杨骅; 王东辉; 张铁军; 侯朝焕

    2009-01-01

    在标签硬件资源受限情况下,为提高UHF RFID系统认证的安全性能,提出一种Hash函数构造算法.算法选择6个混沌映射组合之一来构造Hash函数,通过切换每组中的2个混沌映射生成混沌序列数组,再经过全序列取数策略,将生成的两组数值映射为最终的Hash值.结果分析表明,该算法具有很好的单向性、初值敏感性,在硬件资源和安全性能两方面满足了UHF RFID系统的安全认证要求.

  7. 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

  8. 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

  9. NIBLES - an HI census of stellar mass selected SDSS galaxies: II. Arecibo follow-up HI observations

    CERN Document Server

    Butcher, Z; van Driel, W; Lehnert, M D; Minchin, R

    2016-01-01

    We obtained Arecibo HI line follow-up observations of 154 of the 2600 galaxies in the Nan\\c{c}ay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) sample. These observations are on average four times more sensitive than the original observations at the Nan\\c{c}ay Radio Telescope. The main goal of this survey is to characterize the underlying HI properties of the NIBLES galaxies which were undetected or marginally detected at Nan\\c{c}ay. Of the Nan\\c{c}ay non-detections, 85% were either clearly or marginally detected at Arecibo, while 89% of the Nan\\c{c}ay marginal detections were clearly detected. Based on the statistics of the detections relative to g-i color and r-band luminosity (L$_r$) distribution among our Arecibo observations, we anticipate ~60% of our 867 Nan\\c{c}ay non-detections and marginal detections could be detected at the sensitivity of our Arecibo observations. Follow-up observations of our low luminosity (L$_r$ < 10$^{8.5}$ L$_{\\odot}$) blue sources indicate that they have, on aver...

  10. UHF RFID读写器基带信号FMO解码研究%Baseband signal FM0 decoding research of UHF RFID reader

    Institute of Scientific and Technical Information of China (English)

    张远海; 翁佩纯

    2011-01-01

    Aiming at the requirement of efficient decoding FM0 encoded baseband signal from the UHF RFID reader which complied with ISO/IEC 18000-6B standard ,the article introduced a new method which utilized sub-multiple synchronous and combination checking of multiple sampling and composite IQ quadrature-signal by high-speed MCU. Testing result shows the decoded bit error rate of label information less than 0.5% when the reading distance is 10 meters. A RFID tags decoding method with high accuracy and strong practicability was achieved.%针对符合ISO/IEC 18000-6B标准的UHF RFID读写器需要高效地解码FMO编码的基带信号,从而高效地识别标签返回信息的要求,提出了利用高速MCU分段多次同步、多次采样并结合IQ正文信号复合校验的解码方法对四通道零中频接收机解调出来的FMO基带信号进行解码.通过实验表明,该方法提高了UHF RFID读写器解码FMO信号的效率,在10 m的读卡距离下,解码标签信息的误码率小于0.5%.

  11. Experimental Investigation on Propagation Characteristics of PD Radiated UHF Signal in Actual 252 kV GIS

    Directory of Open Access Journals (Sweden)

    Tianhui Li

    2017-07-01

    Full Text Available For partial discharge (PD diagnostics in gas insulated switchgears (GISs based on the ultra-high-frequency (UHF method, it is essential to study the attenuation characteristics of UHF signals so as to improve the application of the UHF technique. Currently, the performance of UHF has not been adequately considered in most experimental research, while the constructive conclusions about the installation and position of UHF sensors are relatively rare. In this research, by using a previously-designed broadband sensor, the output signal is detected and analyzed experimentally in a 252 kV GIS with L-shaped structure and disconnecting switch. Since the relative position of the sensor and the defect is usually fixed by prior research, three circumferential angle positions of the defect in cross section are performed. The results are studied by time, statistics and frequency analyses. This identifies that the discontinuity conductor of DS will lead to a rise of both the peak to peak value (Vpp and the transmission rate of the UHF signal. Then, the frequency analysis indicates that the reason for the distinction of signal amplitude and transmission rate is that the mode components of the PD signal are distinctively affected by the special structure of GIS. Finally, the optimal circumferential angle position of the UHF Sensor is given based on the comparison of transmission rates.

  12. UHF Signal Processing and Pattern Recognition of Partial Discharge in Gas-Insulated Switchgear Using Chromatic Methodology

    Science.gov (United States)

    Wang, Xiaohua; Li, Xi; Rong, Mingzhe; Xie, Dingli; Ding, Dan; Wang, Zhixiang

    2017-01-01

    The ultra-high frequency (UHF) method is widely used in insulation condition assessment. However, UHF signal processing algorithms are complicated and the size of the result is large, which hinders extracting features and recognizing partial discharge (PD) patterns. This article investigated the chromatic methodology that is novel in PD detection. The principle of chromatic methodologies in color science are introduced. The chromatic processing represents UHF signals sparsely. The UHF signals obtained from PD experiments were processed using chromatic methodology and characterized by three parameters in chromatic space (H, L, and S representing dominant wavelength, signal strength, and saturation, respectively). The features of the UHF signals were studied hierarchically. The results showed that the chromatic parameters were consistent with conventional frequency domain parameters. The global chromatic parameters can be used to distinguish UHF signals acquired by different sensors, and they reveal the propagation properties of the UHF signal in the L-shaped gas-insulated switchgear (GIS). Finally, typical PD defect patterns had been recognized by using novel chromatic parameters in an actual GIS tank and good performance of recognition was achieved. PMID:28106806

  13. Tristatic EISCAT-UHF measurements of the HF modified ionosphere for low background electron temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Westman, A.; Leyser, T.B. [Swedish Institute of Space Physics, Kiruna (Sweden); Wannberg, G. [EISCAT Scientific Association, Kiruna (Sweden)] [and others

    1995-06-01

    The authors report measurements from one of the first tristatic EISCAT-UHF incoherent scatter experiments, where powerful HF beams were transmitted to the daytime F region. Scattered signals were monitored to study spectral structure and time dependence of the excited plasma. The observed plasma turbulence varied considerably, with conditions of low T{sub e} as starting conditions.

  14. Low-Profile UHF Antenna Design Based on an Anisotropic Transverse Resonance Condition

    Science.gov (United States)

    2014-08-01

    MHz, which makes them unsuitable as substrates for UHF antenna structures. The availability of artificial magnetic metamaterials has widened the...Furthermore, the development of artificial magnetic metamaterials allows engineers to separately control the values of both magnetic permeability and...conditions with the conducting walls of the cavity. Furthermore, this report demonstrates that using anisotropic magnetic metamaterials to load this

  15. The effects of single bit quantization on direction of arrival estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2016-01-01

    Phased arrays can be used to estimate the direction-of-arrival (DOA) of UHF RFID tags. To save on energy consumption and hardware costs, in this paper we explore the possibility of using single bit analog-to-digital converters for our phased array setup. This setup consists of an off-the-shelf Impin

  16. 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.

  17. Near field phased array DOA and range estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, Jordy; Kokkeler, André B.J.; Smit, Gerard J.M.

    2015-01-01

    This paper presents a near field localization system based on a phased array for UHF RFID tags. To estimate angle and range the system uses a two-dimensional MUSIC algorithm. A four channel phased array is used to experimentally verify the estimation of angle and range for an EPC gen2 tag. The syste

  18. Determination of the Wavelength of u.h.f. TV Transmissions

    Science.gov (United States)

    Gaskell, D. C.

    1973-01-01

    Describes an experiment suitable for high school physics classes in which students determine the wavelength of electromagnetic radiation of u.h.f. television transmissions. Elaborate equipment is not required, and details are given for the construction of a dipole. (JR)

  19. The effects of single bit quantization on direction of arrival estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2016-01-01

    Phased arrays can be used to estimate the direction-of-arrival (DOA) of UHF RFID tags. To save on energy consumption and hardware costs, in this paper we explore the possibility of using single bit analog-to-digital converters for our phased array setup. This setup consists of an off-the-shelf

  20. Near field phased array DOA and range estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2015-01-01

    This paper presents a near field localization system based on a phased array for UHF RFID tags. To estimate angle and range the system uses a two-dimensional MUSIC algorithm. A four channel phased array is used to experimentally verify the estimation of angle and range for an EPC gen2 tag. The

  1. 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.

  2. Design of a Wideband Inductively Coupled Loop Feed Patch Antenna for UHF RFID Tag

    Directory of Open Access Journals (Sweden)

    M. S. R. Bashri

    2015-04-01

    Full Text Available A planar wideband patch antenna for ultra-high frequency (UHF radio frequency identification (RFID tag for metallic applications is presented in this research work. Three different shape patches are inductively coupled to a triangle loop to form wide impedance bandwidth for universal application UHF (860-960 MHz RFID. The structure of proposed antenna exhibits planar profile to provide ease of fabrication for cost reduction well suited for mass production. The simulation of the antenna was carried out using Finite Element Method (FEM based software, Ansoft HFSS v13. The simulated and measured impedance bandwidth of 113 MHz and 117 MHz (Return Loss≥6 dB were achieved to cover the entire UHF RFID operating frequency band worldwide. The simulated and measured radiation patterns at the operating frequency of 915 MHz are in good agreement. Moreover the simulated minimum antenna gain at the bore sight direction in free space and when mounted on 200 x 200 mm2 metal plate are -15 dBi and -14dBi respectively which is enough to provide reasonable read range over the entire UHF RFID system operating band.

  3. Analysis strategies for high-resolution UHF-fMRI data.

    Science.gov (United States)

    Polimeni, Jonathan R; Renvall, Ville; Zaretskaya, Natalia; Fischl, Bruce

    2017-04-29

    Functional MRI (fMRI) benefits from both increased sensitivity and specificity with increasing magnetic field strength, making it a key application for Ultra-High Field (UHF) MRI scanners. Most UHF-fMRI studies utilize the dramatic increases in sensitivity and specificity to acquire high-resolution data reaching sub-millimeter scales, which enable new classes of experiments to probe the functional organization of the human brain. This review article surveys advanced data analysis strategies developed for high-resolution fMRI at UHF. These include strategies designed to mitigate distortion and artifacts associated with higher fields in ways that attempt to preserve spatial resolution of the fMRI data, as well as recently introduced analysis techniques that are enabled by these extremely high-resolution data. Particular focus is placed on anatomically-informed analyses, including cortical surface-based analysis, which are powerful techniques that can guide each step of the analysis from preprocessing to statistical analysis to interpretation and visualization. New intracortical analysis techniques for laminar and columnar fMRI are also reviewed and discussed. Prospects for single-subject individualized analyses are also presented and discussed. Altogether, there are both specific challenges and opportunities presented by UHF-fMRI, and the use of proper analysis strategies can help these valuable data reach their full potential. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. The effects of single bit quantization on direction of arrival estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, Jordy; Kokkeler, André B.J.; Smit, Gerard J.M.

    2016-01-01

    Phased arrays can be used to estimate the direction-of-arrival (DOA) of UHF RFID tags. To save on energy consumption and hardware costs, in this paper we explore the possibility of using single bit analog-to-digital converters for our phased array setup. This setup consists of an off-the-shelf Impin

  5. HI Clouds detected towards Virgo with the Arecibo Legacy Fast ALFA Survey

    CERN Document Server

    Kent, Brian R

    2007-01-01

    The Arecibo Legacy Fast ALFA survey is in the process of yielding a complete HI dataset of the Virgo Cluster and its environs (Giovanelli et al. 2007, Kent et al., in preparation). Assuming a distance to Virgo of 16.7 Mpc, the minimum detectable HI mass by ALFALFA is of order 2 x 10^7 Msun. A number of the HI detections appear to have interesting properties. Some appear associated with, but offset from, low surface brightness optical counterparts; others, at larger spatial offsets, may be tidally related to optical counterparts. Yet another class includes detections which are not identifiable with any optical counterparts. We present the ALFALFA results on these objects in the Virgo region, as well as followup aperture synthesis observations obtained with the VLA.

  6. The Arecibo Galaxy Environment Survey VIII : Discovery of an Isolated Dwarf Galaxy in the Local Volume

    CERN Document Server

    Taylor, R; Herbst, H; Smith, R

    2014-01-01

    The Arecibo Galaxy Environment Survey (AGES) has detected a nearby HI source at a heliocentric velocity of +363 km/s . The object was detected through its neutral hydrogen emission and has an obvious possible optical counterpart in Sloan Digital Sky Survey (SDSS) data (though it does not have an optical redshift measurement). We discuss three possible scenarios for the object : 1) It is within the Local Group, in which case its HI properties are comparable with recently discovered ultra-compact high velocity clouds; 2) It is just behind the Local Group, in which case its optical characteristics are similar to the newly discovered Leo P galaxy; 3) It is a blue compact dwarf galaxy within the local volume but not associated with the Local Group. We find the third possibility to be the most likely, based on distance estimates from the Tully-Fisher relation and its velocity relative to the Local Group.

  7. Driftscan Surveys in the 21 cm Line with the Arecibo and Nancay Telescopes

    CERN Document Server

    Briggs, F H; Kraan-Korteweg, R C; Van Driel, W

    1997-01-01

    Driftscan methods are highly efficient, stable techniques for conducting extragalactic surveys in the 21cm line of neutral hydrogen. Holding the telescope still while the beam scans the sky at the sidereal rate produces exceptionally stable spectral baselines, increased stability for RFI signals, and excellent diagnostic information about system performance. Data can be processed naturally and efficiently by grouping long sequences of spectra into an image format, thereby allowing thousands of individual spectra to be calibrated, inspected and manipulated as a single data structure with standard tools that already exist in astronomical software. The behavior of spectral standing waves (multi-path effects) can be appraised and excised in this environment, making observations possible while the Sun is up. The method is illustrated with survey data from Arecibo and Nancay.

  8. 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.

  9. Arecibo Pulsar Survey Using ALFA. III. Probing Radio Pulsar Intermittency and Transients

    CERN Document Server

    Deneva, J S; McLaughlin, M A; Nice, D J; Lorimer, D R; Crawford, F; Bhat, N D R; Camilo, F; Champion, D J; Freire, P C C; Edel, S; Kondratiev, V I; Hessels, J W T; Jenet, F A; Kasian, L; Kaspi, V M; Krämer, M; Lazarus, P; Van Leeuwen, J; Ransom, S M; Stairs, I H; Stappers, B W; Brazier, A; Venkataraman, A; Zollweg, J A

    2008-01-01

    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 by detecting isolated dispersed pulses and one of the new discoveries has a duty cycle of 0.01%, the smallest known. The impact of selection effects on the detectability and classification of intermittent sources is discussed, and the relative efficiencies of periodicity vs. single pulse searches are compared for various pulsar classes. We find that scintillation, off-axis detection and few rotation periods within an observation may misrepresent normal periodic pulsars as intermittent sources. Finally, we derive constraints on transient pulse rate and flux density from the PALFA survey parameters and results.

  10. 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.

  11. Meteoroid velocity distribution derived from head echo data collected at Arecibo during regular world day observations

    Directory of Open Access Journals (Sweden)

    M. P. Sulzer

    2004-01-01

    Full Text Available We report the observation and analysis of ionization flashes associated with the decay of meteoroids (so-called head echos detected by the Arecibo 430 MHz radar during regular ionospheric observations in the spring and autumn equinoxes. These two periods allow pointing well-above and nearly-into the ecliptic plane at dawn when the event rate maximizes. The observation of many thousands of events allows a statistical interpretation of the results, which show that there is a strong tendency for the observed meteoroids to come from the apex as has been previously reported (Chau and Woodman, 2004. The velocity distributions agree with Janches et al. (2003a when they are directly comparable, but the azimuth scan used in these observations allows a new perspective. We have constructed a simple statistical model which takes meteor velocities as input and gives radar line of sight velocities as output. The intent is to explain the fastest part of the velocity distribution. Since the speeds interpreted from the measurements are distributed fairly narrowly about nearly 60 km s-1, double the speed of the earth in its orbit, is consistent with the interpretation that many of the meteoroids seen by the Arecibo radar are moving in orbits about the sun with similar parameters as the earth, but in the retrograde direction. However, it is the directional information obtained from the beam-swinging radar experiment and the speed that together provide the evidence for this interpretation. Some aspects of the measured velocity distributions suggest that this is not a complete description even for the fast part of the distribution, and it certainly says nothing about the slow part first described in Janches et al. (2003a. Furthermore, we cannot conclude anything about the entire dust population since there are probably selection effects that restrict the observations to a subset of the population.

  12. 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.

  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. A correlation between RSSI and height in UHF band and comparison of geolocation spectrum database view of TVWS

    CSIR Research Space (South Africa)

    Maliwatu, R

    2016-12-01

    Full Text Available An investigation into the Received Signal Strength Indicator (RSSI) dependency on receiver antenna height in UHF band is conducted. The results show a high correlation between RSSI and height on channels with high signal strength...

  15. P-23 Highlights 6/10/12: Cygnus Dual Beam Radiographic Facility Refurbishment completed at U1A tunnel in Nevada NNSS meeting Level 2 milestone

    Energy Technology Data Exchange (ETDEWEB)

    Deyoung, Anemarie [Los Alamos National Laboratory; Smith, John R. [Los Alamos National Laboratory

    2012-05-03

    A moratorium was placed on U.S. underground nuclear testing in 1992. In response, the Stockpile Stewardship Program was created to maintain readiness of the existing nuclear inventory through several efforts such as computer modeling, material analysis, and subcritical nuclear experiments (SCEs). As in the underground test era, the Nevada National Security Site (NNSS), formerly the Nevada Test Site, provides a safe and secure environment for SCEs by the nature of its isolated and secure facilities. A major tool for SCE diagnosis installed in the 05 drift laboratory is a high energy x-ray source used for time resolved imaging. This tool consists of two identical sources (Cygnus 1 and Cygnus 2) and is called the Cygnus Dual Beam Radiographic Facility (Figs. 2-6). Each Cygnus machine has 5 major elements: Marx Generator, Pulse Forming Line (PFL), Coaxial Transmission Line (CTL), 3-cell Inductive Voltage Adder (IVA), and Rod Pinch Diode. Each machine is independently triggered and may be fired in separate tests (staggered mode), or in a single test where there is submicrosecond separation between the pulses (dual mode). Cygnus must operate as a single shot machine since on each pulse the diode electrodes are destroyed. The diode is vented to atmosphere, cleaned, and new electrodes are inserted for each shot. There is normally two shots per day on each machine. Since its installation in 2003, Cygnus has participated in: 4 Subcritical Experiments (Armando, Bacchus, Barolo A, and Barolo B), a 12 shot plutonium physics series (Thermos), and 2 plutonium step wedge calibration series (2005, 2011), resulting in well over 1000 shots. Currently the Facility is in preparation for 2 SCEs scheduled for this calendar year - Castor and Pollux. Cygnus has performed well during 8 years of operations at NNSS. Many improvements in operations and performance have been implemented during this time. Throughout its service at U1a, major maintenance and replacement of many hardware items

  16. Estimate of Precipitation from the Dual-Beam Airborne Radars in TOGA COARE. Part II: Precipitation Efficiency in the 9 February 1993 MCS.

    Science.gov (United States)

    Oury, Stéphane; Dou, Xiankang; Testud, Jacques

    2000-12-01

    Dual-beam airborne Doppler radars are commonly used in convection experiments for their ability to describe the dynamical structure of weather systems. However, instrumental limitations impose the use of wavelengths such as X-band, which are largely attenuated through heavy rain.This paper is the second of a series of two, which aim at developing schemes for attenuation correction. The authors' final objective is to improve the estimation of precipitation sampled from airborne radars. The first paper was dealing with the application of `differential algorithms' (`stereoradar' and `quad beam') to the independent retrieval of the specific attenuation and nonattenuated reflectivity, which shed some light on the physics of the precipitation. This second paper develops a more extensive procedure based upon the hybridization of a `differential' and an `integral' algorithm. It is much more flexible than the methods proposed in part one and allows full rainfall-rate retrievals in single aircraft experiments. This procedure is applied to the 9 February mesoscale convective system (MCS) study case from Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE), and the impact of the reflectivity correction on the water budget at the cloud system scale is discussed.As expected, the production of water in the 9 February squall line is maximum below the freezing level and is located in the updraft resulting from the interaction between the warm inflow and rear-to-front cold flow. The authors' analysis shows that the precipitation efficiency in the convective region of the system is 31%. Therefore, the large majority of water vapor condensed into cloud droplets and ice crystals does not immediately reach the surface as precipitation. It travels toward the rear of the system at the speed of the horizontal air motion, which suggests a large contribution of the stratiform area in the global water budget. The same calculation performed using raw

  17. Measurement of Coherence Bandwidth in UHF Radio Channels for Narrowband Networks

    Directory of Open Access Journals (Sweden)

    Jaroslaw Sadowski

    2015-01-01

    Full Text Available This paper presents results of investigation on the coherence bandwidth of narrowband radio channels in 430 MHz band. The coherence bandwidth values were estimated from a power delay profile obtained by recording CDMA2000 forward channel signals during real-field measurements in various environments: medium city, flat terrain, and hilly terrain in northern Poland. The results of measurements are compared with characteristic parameters of UHF radio channel models defined for exemplary narrowband digital system from the TETRA standard. In all of the tested environments, the coherence bandwidth values during most of an observation time were much higher than 25 kHz. Therefore, the fading in tested UHF narrowband channels should be classified as flat fading.

  18. 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

  19. Characterization of inkjet-printing HF and UHF antennas for RFID applications

    Science.gov (United States)

    Tarapata, Grzegorz; Paczesny, Daniel; Kawecki, Krzysztof

    2013-10-01

    The aim of this work was to perform a set of RFID antennas on flexible plastic substrates designed for range of HF and UHF band. The samples was fabricated using inkjet printing technology and conductive material base on silver nanopartilces ink. Fabricated antennas have been characterized, and the results were compared with the parameters of antennas made with usage of classical PCB technology on FR4 laminate with copper metallization. The paper presents studies on the impact of elastic substrates and conductive materials on antennas electrical parameters, as well as the communication range of the resulting RFID tags. During the experiment two patterns of HF and three patterns of UHF antennas was examined and the antennas was realized on different types of substrates, such as PET, Kapton® and FR4.

  20. Two-Dimensional River Flow Patterns Observed with a Pair of UHF Radar System

    Directory of Open Access Journals (Sweden)

    Yidong Hou

    2017-01-01

    Full Text Available A pair of ultrahigh-frequency (UHF radars system for measuring the two-dimensional river flow patterns is presented. The system consists of two all-digital UHF radars with exactly the same hardware structure, operating separately at 329–339 MHz and 341–351 MHz. The adoption of direct radio frequency (RF sampling technique and digital pulse compression simplifies the structure of radar system and eliminates the distortion introduced by the analog mixer, which improves the SNR and dynamic range of the radar. The field experiment was conducted at Hanjiang River, Hubei province, China. Over a period of several weeks, the radar-derived surface velocity has been very highly correlated with the measurements of EKZ-I, with a correlation coefficient of 0.958 and a mean square error of 0.084 m/s.

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

    Directory of Open Access Journals (Sweden)

    Simone Zuffanelli

    2016-07-01

    Full Text Available 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.

  2. Design of loop antenna for near-field and far-field UHF RFID applications

    Directory of Open Access Journals (Sweden)

    Ms. Krupali Patil

    2016-02-01

    Full Text Available Radio-frequency-identification (RFID technology has received a lot of attention in warehouse, supply chain, industry, and commerce. As RFID deployment moves from pallet level to item level, it is necessary to identify and track objects by RFID tags at anytime and anywhere. Then, mobile RFID device has advantages in terms of cost, portability and wireless communication. By folded-dipole loop structure with parasitic element, a small antenna size can be achieved. The antenna with different parasitic element size can work on different UHF RFID bands. A novel type of radio frequency identification (RFID reader antenna is proposed for mobile ultrahigh frequency (UHF RFID device. Effects of geometrical length, effect of width of strip, effect of ground plane length on of the frequency verses S parameters and gain of antenna are analyzed.

  3. Arecibo radar imagery of Mars: II. Chryse-Xanthe, polar caps, and other regions

    Science.gov (United States)

    Harmon, John K.; Nolan, Michael C.

    2017-01-01

    We conclude our radar imaging survey of Mars, which maps spatial variations in depolarized radar reflectivity using Arecibo S-band (λ12.6 cm) observations from 2005-2012. Whereas our earlier paper (Harmon et al., 2012, Arecibo radar imagery of Mars: the major volcanic provinces. Icarus 220, 990-1030) covered the volcanic regions of Tharsis, Elysium, and Amazonis, this paper includes non-volcanic regions where hydrologic and impact processes can be the dominant resurfacing agents affecting radar backscatter. Many of the more prominent and interesting radar-bright features outside the major volcanic provinces are located in and around Chryse Planitia and Xanthe Terra. These features are identified with: a basin in northeast Lunae Planum containing the combined deposits from Maja Vallis and Ganges Catena outflows; channel outwash plains in western and southern Chryse basin; plateaus bordering chasma/chaos zones, where surface modification may have resulted from hydrologic action associated with incipient chaos formation; and some bright-ejecta craters in Chryse basin, of a type otherwise rare on Mars. Dark-halo craters have also been identified in Chryse and elsewhere that are similar to those seen in the volcanic provinces. Although the cratered highlands are relatively radar-bland, they do exhibit some bright depolarized features; these include eroded crater rims, several unusual ejecta flows and impact melts, and terrain-softened plains. The rims of large impact basins (Hellas, Argyre, Isidis) show a variety of radar-bright features provisionally identified with massif slopes, erosion sediments, eroded pyroclastics, impact melts, and glacial deposits. The interiors of these basins are largely radar-dark, which is consistent with coverage by rock-free sediments. Tempe Terra and Acheron Fossae show bright features possibly associated with rift volcanism or eroded tectonic structures, and northwest Tempe Terra shows one very bright feature associated with glacial or

  4. A Practical Method for UHF RFID Interrogation Area Measurement Using Battery Assisted Passive Tag

    Science.gov (United States)

    Mitsugi, Jin; Tokumasu, Osamu

    For the success of a large deployment of UHF RFID, easyto-use and low-cost engineering tools to facilitate the performance evaluation are demanded particularly in installations and for trouble shooting. The measurement of interrogation area is one of the most typical industrial demands to establish the stable readability of UHF RFID. Exhaustive repetition of tag position change with a read operation and a usage of expensive measurement equipment or special interrogators are common practices to measure the interrogation area. In this paper, a practical method to measure the interrogation area of a UHF RFID by using a battery assisted passive tag (BAP) is presented. After introducing the fundamental design and performances of the BAP that we have developed, we introduce the measurement method. In the method, the target tag in the target installation is continuously traversed either manually or automatically while it is subjected to a repetitive read of a commercial interrogator. During the target tag traversal, the interrogator's commands are continuously monitored by a BAP. With an extensive analysis on interrogator commands, the BAP can differentiate between its own read timings and those of the target tag. The read timings of the target tag collected by the BAP are recorded synchronously with the target tag position, yielding a map of the interrogation area. The present method does not entail a measurement burden. It is also independent of the choice of interrogator and tag. The method is demonstrated in a practical UHF RFID installation to show that the method can measure a 40mm resolution interrogation area measurement just by traversing the target tag at a slow walking speed, 300mm/sec.

  5. Implementation of Low-Cost UHF RFID Reader Front-Ends with Carrier Leakage Suppression Circuit

    OpenAIRE

    Bin You; Bo Yang; Xuan Wen; Liangyu Qu

    2013-01-01

    A new ultrahigh frequency radio frequency identification (UHF RFID) reader’s front-end circuit which is based on zero-IF, single antenna structure and composed of discrete components has been designed. The proposed design brings a significant improvement of the reading performance by adopting a carrier leakage suppression (CLS) circuit instead of a circulator which is utilized by most of the conventional RF front-end circuit. Experimental results show that the proposed design improves both th...

  6. 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

    2015-11-20

    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.

  7. 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.

  8. 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.

  9. Tunable Compact UHF RFID Metal Tag Based on CPW Open Stub Feed PIFA Antenna

    Directory of Open Access Journals (Sweden)

    Lingfei Mo

    2012-01-01

    Full Text Available For the ultrahigh frequency radio frequency identification (UHF RFID metal tag, it always has the difficulties of compact designing, especially for the conjugate impedance matching, low antenna gain, and fabrication or environmental detuning. In this paper, a tunable compact UHF RFID metal tag is designed based on CPW open stub feed PIFA antenna. By changing the length of the open stub, the impedance of the PIFA antenna could be tuned in a large scale for conjugate impedance matching. The open stub makes it easy to tune the resonant frequency to alleviate the fabrication detuning or the environmental detuning, even after the manufacture. Moreover, the CPW structure of the open stub feed can resist the effects of the metallic surface and increase the antenna gain for the compact PIFA antenna. Modeling analysis and simulation are in good agreement with the measurement results. It showed that the UHF RFID metal tag could be designed compact with good performance based on the CPW open stub feed PIFA antenna.

  10. HI data reduction for the Arecibo Pisces-Perseus Supercluster Survey

    Science.gov (United States)

    Davis, Cory; Johnson, Cory; Craig, David W.; Haynes, Martha P.; Jones, Michael G.; Koopmann, Rebecca A.; Hallenbeck, Gregory L.; Undergraduate ALFALFA Team

    2017-01-01

    The Undergraduate ALFALFA team is currently focusing on the analysis of the Pisces-Perseus Supercluster to test current supercluster formation models. The primary goal of our research is to reduce L-band HI data from the Arecibo telescope. To reduce the data we use IDL programs written by our collaborators to reduce the data and find potential sources whose mass can be estimated by the baryonic Tully-Fisher relation, which relates the luminosity to the rotational velocity profile of spiral galaxies. Thus far we have reduced data and estimated HI masses for several galaxies in the supercluster region.We will give examples of data reduction and preliminary results for both the fall 2015 and 2016 observing seasons. We will also describe the data reduction process and the process of learning the associated software, and the use of virtual observatory tools such as the SDSS databases, Aladin, TOPCAT and others.This research was supported by the NSF grant AST-1211005.

  11. NGC 4254: An Act of Harassment Uncovered by the Arecibo Legacy Fast ALFA Survey

    CERN Document Server

    Haynes, Martha P; Kent, Brian R

    2007-01-01

    We present an HI map constructed from the Arecibo Legacy Fast ALFA (ALFALFA) survey of the surroundings of the strongly asymmetric Virgo cluster Sc galaxy NGC 4254. Noted previously for its lopsided appearance, rich interstellar medium, and extradisk HI emission, NGC 4254 is believed to be entering the Virgo environment for the first time and at high speed. The ALFALFA map clearly shows a long HI tail extending ~250 kpc northward from the galaxy. Embedded as one condensation within this HI structure is the object previously identified as a "dark galaxy": Virgo HI21 (Davies et al. 2004). A body of evidence including its location within and velocity with respect to the cluster and the appearance and kinematics of its strong spiral pattern, extra-disk HI and lengthy HI tail is consistent with a picture of "galaxy harassment" as proposed by Moore et al. (1996a,b; 1998). The smoothly varying radial velocity field along the tail as it emerges from NGC 4254 can be used as a timing tool, if interpreted as resulting f...

  12. The Arecibo Legacy Fast ALFA Survey VII: A Neutral Hydrogen Cloud Complex in the Virgo Cluster

    CERN Document Server

    Kent, Brian R; Giovanelli, Riccardo; Haynes, Martha P; Momjian, Emmanuel; Cortes, Juan R; Hardy, Eduardo; West, Andrew A

    2008-01-01

    We present observations of an HI cloud complex most likely located in the Virgo galaxy cluster, first reported by Kent et al. (2007). The complex consists of five clouds, detected in the data set of the ALFALFA extragalactic HI survey at Arecibo. The clouds have radial velocities between cz~480 and 610 km/s. At the Virgo cluster distance, they are spread over a projected span of 170 kpc and have HI masses ranging from 0.48 to 1.7 x 10^8 Msun. The overall HI mass of the complex is 5.1 x 10^8 Msun. The clouds' velocity widths vary between 50 and 250 km/s. New results of follow-up aperture synthesis observations conducted with the Very Large Array are also presented, which yield a higher resolution view of two of the clouds in the complex. These two resolved clouds show no evidence of symmetry in the gas distribution or of any ordered motions. The possibility that the complex is a group of primordial objects, embedded in their own dark matter halo is thought to be unlikely. Scenarios in which the clouds have bee...

  13. Optically Unseen HI Detections towards the Virgo Cluster detected in the Arecibo Legacy Fast ALFA Survey

    CERN Document Server

    Kent, Brian R; Haynes, Martha P; Saintonge, Amelie; Stierwalt, Sabrina; Balonek, Thomas; Brosch, Noah; Catinella, Barbara; Koopmann, Rebecca A; Momjian, Emmanuel; Spekkens, Kristine

    2007-01-01

    We report the discovery by the Arecibo Legacy Fast ALFA (ALFALFA) survey of eight HI features not coincident with stellar counterparts in the Virgo Cluster region. All of the HI clouds have cz < 3000 km/s and, if at the Virgo distance, HI masses between 1.9 x 10**7 and 1.1 x 10**9 solar masses. Four of the eight objects were reported or hinted at by previous studies and "rediscovered" by ALFALFA. While some clouds appear to be associated with optical galaxies in their vicinity, others show no clear association with a stellar counterpart. Two of them are embedded in relatively dense regions of the cluster and are associated with M49 and M86; they were previously known. The others are mostly located in peripheral regions of the cluster. Especially notable are a concentration of objects towards the so-called M cloud, 3 to 5 degrees to the NW of M87, and a complex of several clouds projected roughly halfway between M87 and M49. The object referred to as VIRGOHI21 and proposed to be a "dark galaxy" is also dete...

  14. The Arecibo Legacy Fast ALFA Survey: VI. Second HI Source Catalog of the Virgo Cluster Region

    CERN Document Server

    Kent, Brian R; Haynes, Martha P; Martin, Ann M; Saintonge, Amélie; Stierwalt, Sabrina; Balonek, Thomas J; Brosch, Noah; Koopmann, Rebecca A

    2008-01-01

    We present the third installment of HI sources extracted from the Arecibo Legacy Fast ALFA extragalactic survey. This dataset continues the work of the Virgo ALFALFA catalog. The catalogs and spectra published here consist of data obtained during the 2005 and 2006 observing sessions of the survey. The catalog consists of 578 HI detections within the range 11h 36m 6.5; (b) high velocity clouds in the Milky Way or its periphery; and (c) signals of lower S/N which coincide spatially with an optical object and known redshift. 75% of the sources are newly published HI detections. Of particular note is a complex of HI clouds projected between M87 and M49 that do not coincide with any optical counterparts. Candidate objects without optical counterparts are few. The median redshift for this sample is 6500 km/s and the cz distribution exhibits the local large scale structure consisting of Virgo and the background void and the A1367-Coma supercluster regime at cz_sun ~7000 km/s. Position corrections for telescope poin...

  15. All-Stokes Parameterization of the Main Beam and First Sidelobe for the Arecibo Radio Telescope

    CERN Document Server

    Heiles, C; Nolan, M L; Lorimer, D; Bhat, R; Ghosh, T K; Howell, E; Lewis, M; O'Neil, K; Salter, C; Stanimirovic, S; Heiles, Carl; Perillat, Phil; Nolan, Michael; Lorimer, Duncan; Bhat, Ramesh; Ghosh, Tapasi; Howell, Ellen; Lewis, Murray; Neil, Karen O'; Salter, Chris; Stanimirovic, Snezana

    2001-01-01

    We describe a scheme that characterizes the main beam and sidelobe in all Stokes parameters employing parameters that allow reconstruction of the complete beam patterns and, also, afford an easy way to see how the beam changes with azimuth, zenith angle, and time. For the main beam in Stokes I the parameters include the beam width, ellipticity and its orientation, coma and its orientation, the point-source gain, the integrated gain (or, equivalently, the main beam efficiency); for the other Stokes parameters the beam parameters include beam squint and beam squash. For the first sidelobe ring in Stokes I the parameters include an 8-term Fourier series describing the height, radius, and radial width; for the other Stokes parameters they include only the sidelobe's fractional polarization. We illustrate the technique by applying it to the Arecibo telescope. The main beam width is smaller and the sidelobe levels higher than for a uniformly-illuminated aperture of the same effective area. These effects are modeled...

  16. 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...

  17. The GALEX Arecibo SDSS Survey. IV. Baryonic Mass-Velocity-Size Relations of Massive Galaxies

    CERN Document Server

    Catinella, Barbara; Schiminovich, David; Lemonias, Jenna; Scannapieco, Cecilia; Wang, Jing; Fabello, Silvia; Hummels, Cameron; Moran, Sean M; Wu, Ronin; Cooper, Andrew P; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Saintonge, Amélie

    2011-01-01

    We present dynamical scaling relations for a homogeneous and representative sample of ~500 massive galaxies, selected only by stellar mass (>10^10 Msun) and redshift (0.025Arecibo SDSS Survey. We compare baryonic Tully-Fisher (BTF) and Faber-Jackson (BFJ) relations for this sample, and investigate how galaxies scatter around the best fits obtained for pruned subsets of disk-dominated and bulge-dominated systems. The BFJ relation is significantly less scattered than the BTF when the relations are applied to their maximum samples, and is not affected by the inclination problems that plague the BTF. Disk-dominated, gas-rich galaxies systematically deviate from the BFJ relation defined by the spheroids. We demonstrate that by applying a simple correction to the stellar velocity dispersions that depends only on the concentration index of the galaxy, we are able to bring disks and spheroids onto the same dynamical relation -- in other words, we obtain a generalized BFJ re...

  18. The GALEX Arecibo SDSS Survey II: The Star Formation Efficiency of Massive Galaxies

    CERN Document Server

    Schiminovich, David; Kauffmann, Guinevere; Fabello, Silvia; Wang, Jing; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Basu-Zych, Antara R; Blanton, Michael R; Brinchmann, Jarle; Budavari, Tamas; Goncalves, Thiago; Johnson, Benjamin D; Kennicutt, Robert C; Madore, Barry F; Martin, Christopher D; Rich, Michael R; Tacconi, Linda J; Thilker, David A; Wild, Vivienne; Wyder, Ted K

    2010-01-01

    We use measurements of the HI content, stellar mass and star formation rates in ~190 massive galaxies with stellar masses greater than 10^10 Msun, obtained from the Galex Arecibo SDSS Survey (GASS) described in Paper I (Catinella et al. 2010) to explore the global scaling relations associated with the bin-averaged ratio of the star formation rate over the HI mass, which we call the HI-based star formation efficiency (SFE). Unlike the mean specific star formation rate, which decreases with stellar mass and stellar mass surface density, the star formation efficiency remains relatively constant across the sample with a value close to SFE = 10^-9.5 yr^-1 (or an equivalent gas consumption timescale of ~3 Gyr). Specifically, we find little variation in SFE with stellar mass, stellar mass surface density, NUV-r color and concentration. We interpret these results as an indication that external processes or feedback mechanisms that control the gas supply are important for regulating star formation in massive galaxies....

  19. Arecibo and Goldstone Radar Imaging of Near-Earth Asteroid 2005 WC1

    Science.gov (United States)

    Lawrence, Kenneth J.; Benner, Lance A. M.; Brozovic, Marina; Jao, Joseph S.; Giorgini, Jon D.; Slade, Martin A.; Jurgens, Raymond F.; Nolan, Michael C.; Howell, Ellen S.; Taylor, Patrick A.

    2016-10-01

    We report radar observations of near-Earth asteroid 2005 WC1 that were obtained at Arecibo (2380 MHz, 13 cm) and Goldstone (8560 MHz, 3.5 cm) on 2005 December 14-15 during the asteroid's approach within 0.020 au (7.7 lunar distances). The asteroid was a strong radar target and we obtained a sequence of delay-Doppler images with resolutions as fine as 7.5 m/pixel. The radar images reveal an angular object with several pronounced facets, radar-dark regions, and an estimated diameter of ~0.4 km. The rotation of the facets in the images gives a rotation period of 2.57 h that is consistent with the estimate of 2.582 h ± 0.002 h reported by Miles et al. (private communication). 2005 WC1 has a circular polarization ratio of 1.12 ± 0.02 that is one of the highest values known, suggesting a structurally-complex near-surface at centimeter decimeter spatial scales. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

  20. Bistatic radar observations of the Moon using Mini-RF on LRO and the Arecibo Observatory

    Science.gov (United States)

    Patterson, G. W.; Stickle, A. M.; Turner, F. S.; Jensen, J. R.; Bussey, D. B. J.; Spudis, P.; Espiritu, R. C.; Schulze, R. C.; Yocky, D. A.; Wahl, D. E.; Zimmerman, M.; Cahill, J. T. S.; Nolan, M.; Carter, L.; Neish, C. D.; Raney, R. K.; Thomson, B. J.; Kirk, R.; Thompson, T. W.; Tise, B. L.; Erteza, I. A.; Jakowatz, C. V.

    2017-02-01

    The Miniature Radio Frequency (Mini-RF) instrument aboard NASA's Lunar Reconnaissance Orbiter (LRO) is a hybrid dual-polarized synthetic aperture radar (SAR) that operated in concert with the Arecibo Observatory to collect bistatic radar data of the lunar nearside from 2012 to 2015. The purpose of this bistatic campaign was to characterize the radar scattering properties of the surface and near-surface, as a function of bistatic angle, for a variety of lunar terrains and search for a coherent backscatter opposition effect indicative of the presence of water ice. A variety of lunar terrain types were sampled over a range of incidence and bistatic angles; including mare, highland, pyroclastic, crater ejecta, and crater floor materials. Responses consistent with an opposition effect were observed for the ejecta of several Copernican-aged craters and the floor of the south-polar crater Cabeus. The responses of ejecta material varied by crater in a manner that suggests a relationship with crater age. The response for Cabeus was observed within the portion of its floor that is not in permanent shadow. The character of the response differs from that of crater ejecta and appears unique with respect to all other lunar terrains observed. Analysis of data for this region suggests that the unique nature of the response may indicate the presence of near-surface deposits of water ice.

  1. Initial HI results from the Arecibo Pisces-Perseus Supercluster Survey

    Science.gov (United States)

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

    2017-01-01

    The Arecibo Pisces-Perseus Supercluster Survey is a targeted HI survey of galaxies that began its second observing season in October 2016. The survey is conducted by members of the Undergraduate ALFALFA Team (UAT) and extensively involves undergraduates in observations, data reduction, and analysis. It aims to complement the HI sources identified by the ALFALFA extragalactic HI line survey by probing deeper in HI mass (to lower masses) than the legacy survey itself. Measurements of the HI line velocity widths will be combined with uniform processing of images obtained in the SDSS and GALEX public databases to localize the sample within the baryonic Tully Fisher relation, allowing estimates of their redshift-independent distances and thus their peculiar velocities.The survey is designed to constrain Pisces-Perseus Supercluster infall models by producing 5-σ detections of infall velocities to a precision of about 500 km/s. By targeting galaxies based on SDSS and GALEX photometry, we have achieved detection rates of 68% of the galaxies in our sample. We will discuss the target selection process, HI velocities and mass estimates from the 2015 fall observing season, preliminary results from 2016 observations, and preliminary comparisons with inflow models predicted by numerical simulations.This work has been supported by NSF grants AST-1211005, AST-1637339, AST-1637262.

  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. 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...

  4. 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 ...

  5. FOUR HIGHLY DISPERSED MILLISECOND PULSARS DISCOVERED IN THE ARECIBO PALFA GALACTIC PLANE SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Stovall, K. [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL (United Kingdom); Nice, D. J. [Department of Physics, Lafayette College, Easton, PA 18042 (United States); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Lazarus, P. [Department of Physics, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Hessels, J. W. T. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990-AA Dwingeloo (Netherlands); Freire, P. C. C.; Champion, D. J.; Desvignes, G. [Max-Planck-Institut fuer Radioastronomie, auf dem Huegel 69, D-53121 Bonn (Germany); Allen, B. [Albert-Einstein-Institut, Max-Planck-Institut fuer Gravitationsphysik, D-30167 Hannover (Germany); Bhat, N. D. R.; Camilo, F. [Center for Astrophysics and Supercomputing, Swinburne University, Hawthorn, Victoria 3122 (Australia); Bogdanov, S. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Brazier, A.; Chatterjee, S.; Cordes, J. M. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace, LPC2E, CNRS et Universite d' Orleans, and Station de radioastronomie de Nancay, Observatoire de Paris, F-18330 Nancay (France); Deneva, J. S., E-mail: fcrawfor@fandm.edu [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); and others

    2012-09-20

    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{sup -3}), are distant ({approx}> 3.4 kpc), faint at 1.4 GHz ({approx}< 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 15. The discovery of these MSPs illustrates the power of PALFA for finding weak, distant MSPs at low-Galactic latitudes. This is important for accurate estimates of the Galactic MSP population and for the number of MSPs that the Square Kilometer Array can be expected to detect.

  6. Interoperation of an UHF RFID Reader and a TCP/IP Device via Wired and Wireless Links

    Directory of Open Access Journals (Sweden)

    Ik Soo Jin

    2011-11-01

    Full Text Available A main application in radio frequency identification (RFID sensor networks is the function that processes real-time tag information after gathering the required data from multiple RFID tags. The component technologies that contain an RFID reader, called the interrogator, which has a tag chip, processors, coupling antenna, and a power management system have advanced significantly over the last decade. This paper presents a system implementation for interoperation between an UHF RFID reader and a TCP/IP device that is used as a gateway. The proposed system consists of an UHF RFID tag, an UHF RFID reader, an RF end-device, an RF coordinator, and a TCP/IP I/F. The UHF RFID reader, operating at 915 MHz, is compatible with EPC Class-0/Gen1, Class-1/Gen1 and 2, and ISO18000-6B. In particular, the UHF RFID reader can be combined with the RF end-device/coordinator for a ZigBee (IEEE 802.15.4 interface, which is a low-power wireless standard. The TCP/IP device communicates with the RFID reader via wired links. On the other hand, it is connected to the ZigBee end-device via wireless links. The web based test results show that the developed system can remotely recognize information of multiple tags through the interoperation between the RFID reader and the TCP/IP device.

  7. Interoperation of an UHF RFID reader and a TCP/IP device via wired and wireless links.

    Science.gov (United States)

    Lee, Sang Hoon; Jin, Ik Soo

    2011-01-01

    A main application in radio frequency identification (RFID) sensor networks is the function that processes real-time tag information after gathering the required data from multiple RFID tags. The component technologies that contain an RFID reader, called the interrogator, which has a tag chip, processors, coupling antenna, and a power management system have advanced significantly over the last decade. This paper presents a system implementation for interoperation between an UHF RFID reader and a TCP/IP device that is used as a gateway. The proposed system consists of an UHF RFID tag, an UHF RFID reader, an RF end-device, an RF coordinator, and a TCP/IP I/F. The UHF RFID reader, operating at 915 MHz, is compatible with EPC Class-0/Gen1, Class-1/Gen1 and 2, and ISO18000-6B. In particular, the UHF RFID reader can be combined with the RF end-device/coordinator for a ZigBee (IEEE 802.15.4) interface, which is a low-power wireless standard. The TCP/IP device communicates with the RFID reader via wired links. On the other hand, it is connected to the ZigBee end-device via wireless links. The web based test results show that the developed system can remotely recognize information of multiple tags through the interoperation between the RFID reader and the TCP/IP device.

  8. Interoperation of an UHF RFID Reader and a TCP/IP Device via Wired and Wireless Links

    Science.gov (United States)

    Lee, Sang Hoon; Jin, Ik Soo

    2011-01-01

    A main application in radio frequency identification (RFID) sensor networks is the function that processes real-time tag information after gathering the required data from multiple RFID tags. The component technologies that contain an RFID reader, called the interrogator, which has a tag chip, processors, coupling antenna, and a power management system have advanced significantly over the last decade. This paper presents a system implementation for interoperation between an UHF RFID reader and a TCP/IP device that is used as a gateway. The proposed system consists of an UHF RFID tag, an UHF RFID reader, an RF end-device, an RF coordinator, and a TCP/IP I/F. The UHF RFID reader, operating at 915 MHz, is compatible with EPC Class-0/Gen1, Class-1/Gen1 and 2, and ISO18000-6B. In particular, the UHF RFID reader can be combined with the RF end-device/coordinator for a ZigBee (IEEE 802.15.4) interface, which is a low-power wireless standard. The TCP/IP device communicates with the RFID reader via wired links. On the other hand, it is connected to the ZigBee end-device via wireless links. The web based test results show that the developed system can remotely recognize information of multiple tags through the interoperation between the RFID reader and the TCP/IP device. PMID:22346665

  9. Bistatic Radar Observations of the Moon using MINI-RF on LRO and the Arecibo Observatory

    Science.gov (United States)

    Patterson, G.; Bussey, B.

    2013-12-01

    The Mini-RF team is acquiring bistatic radar measurements of the lunar surface to understand the scattering properties of materials as a function of phase angle. These observations have produced the first lunar bistatic radar images ever collected with non-zero phase angles. The goal of these observations is to differentiate between scatter-ing indicative of surfaces that are rough versus surfaces that harbor water ice in quantities detectible by a radar sys-tem operating at a wavelength of 12.6 cm. Radar observations of planetary surfaces provide unique information on the structure (i.e., roughness) and dielec-tric properties of surface and buried materials. These data can be acquired using a monostatic architecture, where a single antenna serves as the signal transmitter and receiver, or they can be acquired using a bistatic architecture, where a signal is transmitted from one location and received at another. The former provides information on the scattering properties of a target surface at zero phase. The latter provides the same information over a variety of phase angles. NASA's Mini-RF instrument on the Lunar Reconnaissance Orbiter and the Arecibo Observatory in Puerto Rico are currently operating in a bistatic architecture (the Arecibo Observatory serves as the transmitter and Mini-RF serves as the receiver). This architecture maintains the hybrid dual-polarimetric nature of the Mini-RF in-strument and, therefore, allows for the calculation of the Stokes parameters (S1, S2, S3, S4) that characterize the backscattered signal (and the products derived from those parameters). A common product derived from the Stokes parameters is the Circular Polarization Ratio (CPR). High CPR val-ues can serve as an indicator of rough surfaces or as an indicator of the presence of water ice. Recent work using monostatic radar data and inferences from surface geology suggests that anomalously high CPR values associated with some polar lunar craters are indicative of the

  10. Observing the Plasma-Physical Processes of Pulsar Radio Emission with Arecibo

    Science.gov (United States)

    Rankin, Joanna M.

    2017-01-01

    With their enormous densities and fields, neutron stars entail some of the most exotic physics in the cosmos. Similarly, the physical mechanisms of pulsar radio emission are no less exotic, and we are only now beginning to understand them. The talk will provide an introduction to the phenomenology of radio pulsar emission and focus on those aspects of the exquisite Arecibo observations that bear on their challenging emission physics.The commonalities of the radio beamforms of most slow pulsars (and some millisecond pulsars) argue strongly that their magnetic fields have a nearly dipolar structure at the height of their radio emission regions. These heights can often be determined by aberration/retardation analyses. Similarly, measurement of the orientation of the polarized radio emission with respect to the emitting magnetic field facilitates identification of the physical(X/O) emission modes and study of the plasma coupling to the electromagnetic radiation.While the physics of primary plasma generation above the pulsar polar cap is only beginning to be understood, it is clear that the radio pulsars we see are able to generate copious amounts of electron-positron plasma in their emission regions. Within the nearly dipolar field structure of these emission regions, the plasma density is near to that of the Goldreich-Julian model, and so the physical conditions in these regions can be accurately estimated.These conditions show that the plasma frequencies in the emission regions are much higher than the frequency of the emitted radiation, such that the plasma couples most easily to the extraordinary mode as observed. Therefore, the only surviving emission mechanism is curvature radiation from charged solitons, produced by the two-stream instability. Such soliton emission has probably been observed directly in the Crab pulsar; however, a physical theory of charged soliton radiation does not yet exist.

  11. NEW DISCOVERIES FROM THE ARECIBO 327 MHz DRIFT PULSAR SURVEY RADIO TRANSIENT SEARCH

    Energy Technology Data Exchange (ETDEWEB)

    Deneva, J. S. [National Research Council, resident at the Naval Research Laboratory, Washington, DC 20375 (United States); Stovall, K. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States); McLaughlin, M. A.; Bagchi, M.; Garver-Daniels, N. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Bates, S. D. [The Institute of Mathematical Sciences, Chennai, 600113 (India); Freire, P. C. C.; Martinez, J. G. [Max-Planck-Institut für Radioastronomie, Bonn (Germany); Jenet, F. [Center for Advanced Radio Astronomy, Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States)

    2016-04-10

    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{sup −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{sup −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{sup 5} day{sup −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.

  12. Mini-RF and Arecibo Observatory Bistatic Observations of the Moon

    Science.gov (United States)

    Patterson, G.; Bussey, B.; Stickle, A. M.; Turner, F. S.; Jensen, J. R.; Nolan, M. C.; Yocky, D. A.; Wahl, D. E.

    2015-12-01

    The Mini-RF instrument aboard NASA's Lunar Reconnaissance Orbiter (LRO) is a hybrid dual-polarized synthetic aperture radar (SAR) and has been operating in concert with the Arecibo Observatory since 2012 to collect bistatic radar data of the Moon. Approximately 28 bistatic observations, covering a variety of terrains on the lunar nearside, have been made using this mode of operation. Laboratory data and analog experiments, at optical wavelengths, have shown that the scattering properties of lunar materials (e.g., the roughness) can be sensitive to variations in bistatic angle. This sensitivity manifests as an opposition effect and likely involves contributions from shadow hiding at low angles and coherent backscatter near 0°. Analog experiments and theoretical work have shown that water ice is also sensitive to variations in bistatic angle. Differences in the character of the opposition response of these materials offer an opportunity to differentiate between them, an issue that has been problematic for previous radar studies of the Moon. Observations that include mare materials, highland materials, and pyroclastic deposits have not shown an opposition response over for bistatic angles of ~0.1° to 30°. Observations of the ejecta blankets of young, fresh craters have shown an opposition response for the same range of bistatic angles. The character of the response varies for each crater and is likely related to differences in target properties of the surface and exposure age of the blanket. Observations of portions of the floor of the south polar crater Cabeus have also been acquired for the same range of bistatic angles. The character of the radar response from the crater, as a function of bistatic angle, appears unique with respect to all other lunar terrains observed.

  13. UHF Passive RFID标签最大阅读距离的研究%Study on maximum reading distance of UHF Passive RFID tag

    Institute of Scientific and Technical Information of China (English)

    谢晶晶; 赵东东

    2012-01-01

    特定的RFID阅读器与标签之间的最大阅读距离是衡量标签性能的一个重要因素.首先介绍了RFID工作原理,同时介绍本文所要研究的无源UHF RFID系统.在前向链路方向,根据福利斯空间公式推出标签最大阅读距离的理论公式,并且用MATLAB软件仿真了功率传输系数、标签工作频率与阅读距离之间的关系,然后分析得到了后向链路方向阅读器所能接收到的反向散射能量的公式,通过代入实际数据证实了最大阅读距离公式的理论上的可靠性.在此基础上,搭建一个实际的测量最大距离的实验平台,从而通过实际试验验证推出的理论计算公式的准确性程度的确是比较高的,最后又根据推导出来的的最大阅读距离公式,从标签和阅读器2个方面分析了影响最大阅读距离的因素和提高最大阅读距离的方法.研究对象是超高频(UHF) (902~928 MHz)的无源RFID系统,阅读器与标签的天线都是线极化单天线.%The maximum read distance is an important factor to mfaiurp the performance of the tag. The principle of the RFID system is introduced, then the principle of the passive UHF RFID system is given. In the direction of the forward link,the theoretical maximum reading distance formula is derived according to the Friis formula. Then the relation between the power transmitting coefficient and the maximum reading distance and the relation between the working frequency and the maximum reading distance are simulated using MATLAB. Then the reverse scattering power formula which the reader can get is derived,and the theoretical reliability of the maximum reading range is verified according to the substitution of the practical data. On the basis of it,a experiment platform is built to measure the practical maximum reading distance, then the distinction between the theoretical maximum reading distance and the practical maximum reading distance is small, so the practical reliability of

  14. Extending ALFALFA in the Direction of the Pisces-Perseus Supercluster with the Arecibo L-Band Wide Receiver

    Science.gov (United States)

    O'Donoghue, Aileen A.; Haynes, Martha P.; Koopmann, Rebecca A.; Jones, Michael G.; Hallenbeck, Gregory L.; Giovanelli, Riccardo; Hoffman, Lyle; Craig, David W.; Undergraduate ALFALFA Team

    2017-01-01

    We have completed three “Harvesting ALFALFA” Arecibo observing programs in the direction of the Pisces-Perseus Supercluster (PPS) since ALFALFA observations were finished in 2012. The first was to perform follow-up observations on high signal-to-noise (S/N > 6.5) ALFALFA detections needing confirmation and low S/N sources lacking optical counterparts. A few more high S/N objects were observed in the second program along with targets visually selected from the Sloan Digital Sky Survey (SDSS). The third program included low S/N ALFALFA sources having optical counterparts with redshifts that were unknown or differed from the ALFALFA observations. It also included more galaxies selected from SDSS by eye and by Structured Query Language (SQL) searches with parameters intended to select galaxies at the distance of the PPS (~6,000 km/s). We used pointed basic Total-Power Position-Switched Observations in the 1340 - 1430 MHz ALFALFA frequency range. For sources of known redshift, we used the Wideband Arecibo Pulsar Processors (WAPP’s) , while for sources of unknown redshift we utilized a hybrid/dual bandwidth Doppler tracking mode using the Arecibo Interim 50-MHz Correlator with 9-level sampling.Results confirmed that a few high S/N ALFALFA sources are spurious as expected from the work of Saintonge (2007), low S/N ALFALA sources lacking an optical counterpart are all likely to be spurious, but low S/N sources with optical counterparts are generally reliable. Of the optically selected sources, about 80% were detected and tended to be near the distance of the PPS.This work has been supported by NSF grant AST-1211005.

  15. Implementation of Low-Cost UHF RFID Reader Front-Ends with Carrier Leakage Suppression Circuit

    Directory of Open Access Journals (Sweden)

    Bin You

    2013-01-01

    Full Text Available A new ultrahigh frequency radio frequency identification (UHF RFID reader’s front-end circuit which is based on zero-IF, single antenna structure and composed of discrete components has been designed. The proposed design brings a significant improvement of the reading performance by adopting a carrier leakage suppression (CLS circuit instead of a circulator which is utilized by most of the conventional RF front-end circuit. Experimental results show that the proposed design improves both the sensitivity and detection range compared to the conventional designs.

  16. 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....

  17. 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.

  18. Theoretical Findings and Measurements on Planning a UHF RFID System inside a Room

    Directory of Open Access Journals (Sweden)

    A. C. Polycarpou

    2011-06-01

    Full Text Available This paper investigates the problem of improving the identification performance of a UHF RFID system inside a room. We assume static reader, passive tags and availability of commodity antennas. A ray-tracing propagation model is developed that includes multipath in 3D space. It is found that careful selection of reader antenna placement and tilting must be performed to control destructive interference effects. Furthermore, 3D coverage performance gains on the order of 10% are observed by implementing tags’ diversity. A device that successfully manipulates destructive interference is introduced. All theoretical findings are verified by measurements. Finally, a method to perform propagation measurements with commodity RFID hardware is demonstrated.

  19. 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.

  20. The GALEX Arecibo SDSS Survey. I. Gas Fraction Scaling Relations of Massive Galaxies and First Data Release

    CERN Document Server

    Catinella, Barbara; Kauffmann, Guinevere; Fabello, Silvia; Wang, Jing; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Basu-Zych, Antara R; Blanton, Michael R; Brinchmann, Jarle; Budavári, Tamás; Gonçalves, Thiago; Johnson, Benjamin D; Kennicutt, Robert C; Madore, Barry F; Martin, Christopher D; Rich, Michael R; Tacconi, Linda J; Thilker, David A; Wild, Vivienne; Wyder, Ted K

    2009-01-01

    We introduce the GALEX Arecibo SDSS Survey (GASS), an on-going large program that is gathering high quality HI-line spectra using the Arecibo radio telescope for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025

  1. Blind Extragalactic HI Surveys with the Arecibo and Green Bank Telescopes: I. Simulations and Strategies for Survey Design

    Science.gov (United States)

    Giovanelli, R.; Haynes, M. P.; Spekkens, K.; Springob, C. M.; Masters, K. L.; Saintonge, A.; Catinella, B.; Kent, B.; Maddalena, R. J.; Magnani, L.; Koopmann, R. A.

    2003-12-01

    The currently popular Λ CDM framework of evolution of cosmic structure predicts a population of low mass halos that far exceeds that of dwarf galaxies. Low mass halos could, however, have retained little of their initial baryonic mass fraction, and their star formation efficiency could be very low. The possibility of detecting such systems in the 21 cm HI line has been investigated by several teams, and blind extragalactic HI surveys have been undertaken to date, pushing estimates of the HI Mass Function to limits approaching 107 M⊙ (Zwaan et al. 1997, Rosenberg and Schneider 2002, Zwaan et al. 2003). Extrapolations of those estimates to 106 M⊙ disagree with each other quite substantially. Since these low mass objects may represent the population of low mass halos predicted to exist by numerical Λ CDM simulations, the determination of their space density and its possible dependence on galaxy environment remains an important goal. Systems of very low HI mass can only be detected at relatively small distances. It thus becomes important to optimize the survey design, matching it to the local characteristics of the cosmic density field. We present results of various survey simulations, some currently underway with the single-beam Arecibo and Green Bank telescopes and future ones that will be enabled with the advent of the Arecibo L-band feed array in late 2004. This work is partially funded by NSF grant AST-0307661.

  2. Fade measurements at L-band and UHF in mountainous terrain for land mobile satellite systems

    Science.gov (United States)

    Vogel, Wolfhard J.; Goldhirsh, Julius

    1988-01-01

    Fading results related to land mobile satellite communications at L-band (1502 MHz) and UHF (870 MHz) are described. These results were derived from an experiment performed in a series of canyon passes in the Boulder, Colorado region of the US. The experimental configuration involved a helicopter as the source platform, which maintained a relatively fixed geometry with a mobile van containing the receiver and data-acquisition system. An unobstructed line of sight between the radiating sources and the receiving van was, for the most part, also maintained. In this configuration, the dominant mechanism causing signal fading (or enhancement) is a result of multipath. The resulting fade distributions demonstrated that at the 1 percent and 5 percent levels, 5.5- and 2.6-dB fades were on the average exceeded at L-band and 4.8- and 2.4-dB at UHF, respectively, for a path elevation angle of 45 deg. The canyon results as compared with previous roadside-tree-shadowing results demonstrate that the deciding factor dictating fade margin for future land mobile satellite systems is tree shadowing rather than fades caused by multipath.

  3. A Novel Partial Discharge Localization Method in Substation Based on a Wireless UHF Sensor Array.

    Science.gov (United States)

    Li, Zhen; Luo, Lingen; Zhou, Nan; Sheng, Gehao; Jiang, Xiuchen

    2017-08-18

    Effective Partial Discharge (PD) localization can detect the insulation problems of the power equipment in a substation and improve the reliability of power systems. Typical Ultra-High Frequency (UHF) PD localization methods are mainly based on time difference information, which need a high sampling rate system. This paper proposes a novel PD localization method based on a received signal strength indicator (RSSI) fingerprint to quickly locate the power equipment with potential insulation defects. The proposed method consists of two stages. In the offline stage, the RSSI fingerprint data of the detection area is measured by a wireless UHF sensor array and processed by a clustering algorithm to reduce the PD interference and abnormal RSSI values. In the online stage, when PD happens, the RSSI fingerprint of PD is measured via the input of pattern recognition for PD localization. To achieve an accurate localization, the pattern recognition process is divided into two steps: a preliminary localization is implemented by cluster recognition to reduce the localization region, and the compressed sensing algorithm is used for accurate PD localization. A field test in a substation indicates that the mean localization error of the proposed method is 1.25 m, and 89.6% localization errors are less than 3 m.

  4. 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.

  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. 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.

  7. 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

    2016-03-26

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

    Science.gov (United States)

    Sowade, Enrico; Göthel, Frank; Zichner, Ralf; Baumann, Reinhard R.

    2015-03-01

    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 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.

  9. UHF front-end feeding RFID-based body sensor networks by exploiting the reader signal

    Science.gov (United States)

    Pasca, M.; Colella, R.; Catarinucci, L.; Tarricone, L.; D'Amico, S.; Baschirotto, A.

    2016-05-01

    This paper presents an integrated, high-sensitivity UHF radio frequency identification (RFID) power management circuit for body sensor network applications. The circuit consists of a two-stage RF-DC Dickson's rectifier followed by an integrated five-stage DC-DC Pelliconi's charge pump driven by an ultralow start-up voltage LC oscillator. The DC-DC charge pump interposed between the RF-DC rectifier and the output load provides the RF to load isolation avoiding losses due to the diodes reverse saturation current. The RF-DC rectifier has been realized on FR4 substrate, while the charge pump and the oscillator have been realized in 180 nm complementary metal oxide semiconductor (CMOS) technology. Outdoor measurements demonstrate the ability of the power management circuit to provide 400 mV output voltage at 14 m distance from the UHF reader, in correspondence of -25 dBm input signal power. As demonstrated in the literature, such output voltage level is suitable to supply body sensor network nodes.

  10. SAR exposure from UHF RFID reader in adult, child, pregnant woman, and fetus anatomical models.

    Science.gov (United States)

    Fiocchi, Serena; Markakis, Ioannis A; Ravazzani, Paolo; Samaras, Theodoros

    2013-09-01

    The spread of radio frequency identification (RFID) devices in ubiquitous applications without their simultaneous exposure assessment could give rise to public concerns about their potential adverse health effects. Among the various RFID system categories, the ultra high frequency (UHF) RFID systems have recently started to be widely used in many applications. This study addresses a computational exposure assessment of the electromagnetic radiation generated by a realistic UHF RFID reader, quantifying the exposure levels in different exposure scenarios and subjects (two adults, four children, and two anatomical models of women 7 and 9 months pregnant). The results of the computations are presented in terms of the whole-body and peak spatial specific absorption rate (SAR) averaged over 10 g of tissue to allow comparison with the basic restrictions of the exposure guidelines. The SAR levels in the adults and children were below 0.02 and 0.8 W/kg in whole-body SAR and maximum peak SAR levels, respectively, for all tested positions of the antenna. On the contrary, exposure of pregnant women and fetuses resulted in maximum peak SAR(10 g) values close to the values suggested by the guidelines (2 W/kg) in some of the exposure scenarios with the antenna positioned in front of the abdomen and with a 100% duty cycle and 1 W radiated power.

  11. Performance and Benchmarking of Multisurface UHF RFID Tags for Readability and Reliability

    Directory of Open Access Journals (Sweden)

    Joshua Bolton

    2017-01-01

    Full Text Available As the price of passive radio frequency identification (RFID tags continues to decrease, more and more companies are considering item-level tagging. Although the use of RFID is simple, its proper application should be studied to achieve maximum efficiency and utilization in the industry. This paper is intended to demonstrate the test results of various multisurface UHF tags from different manufacturers for their readability under varying conditions such as orientation of tags with respect to reader, distance of tag from the reader, and materials used for embedding tags. These conditions could affect the reliability of RFID systems used for varied applications. In this paper, we implement a Design for Six Sigma Research (DFSS-R methodology that allows for reliability testing of RFID systems. In this paper, we have showcased our results about the benchmarking of UHF RFID tags and have put forward an important observation about the blind spots observed at different distances and orientations along different surfaces, which is primarily due to the polarity of the antenna chosen.

  12. Polarimetric Analysis of the Interference from Base Stations to UHF-band Radar

    Directory of Open Access Journals (Sweden)

    Ren Bo

    2016-04-01

    Full Text Available Radar detection and tracking performance in the UHF-band can be influenced by the downlink signals of communication base stations. The polarimetric properties of interference from base stations are measured and analyzed as a basis for suppressing this type of interference by a polarization processing method. In this study, we establish signal models from the base station for dual-polarization UHF-band radar. We express the Probability Density Functions (PDF of the estimated polarization ratio and degree of polarization in a closed form and use them to describe the statistical properties of the interference environment. We developed polarimetric radar reception experiments for the signals from both Single-Base Stations (SBS and Multi-Base Stations (MBS. Experimental results proved that deterministic polarized descriptions are appropriate only for signals from SBS but not from MBS or from stations with a low DoP (Degree of Polarization. However, the proposed statistical method can be used to describe both SBS and MBS cases, which we demonstrated by comparing the theoretical models with real measurement data.

  13. 无源UHF RFID电子标签模拟前端设计%Design of an Analog Front End for Passive UHF RFID Transponder IC

    Institute of Scientific and Technical Information of China (English)

    陈力颖; 吴顺华; 毛陆虹; 郝先人

    2007-01-01

    This paper introduces a high-performance analog front end for a passive UHF RFID transponder IC,which is compatible with the ISO/IEC 18000-6B standard,operating at the 915MHz ISM band with a total supply current consumption less than 8μA.There are no external components,except for the antenna.The passive IC's power supply is taken from the energy of the received RF electromagnetic field with the help of a Schottky diode rectifier.The RFID analog front end includes a local oscillator,clock generator,power on reset circuit,matching network and backscatter,rectifier,regulator,and AM demodulator.The IC,whose reading distance is more than 3m,is fabricated with a Chartered 0.35μm two-poly four-metal CMOS process with Schottky diodes and is EEPROM supported.The core size is 300μm×720μm.%提出了一种符合ISO/IEC 18000-6B标准的高性能无源UHF RFID电子标签模拟前端,在915MHz ISM频带下工作时其电流小于8μA.该模拟前端除天线外无外接元器件,通过肖特基二极管整流器从射频电磁场接收能量.该RFID模拟前端包括本地振荡器、时钟产生电路、复位电路、匹配网络和反向散射电路、整流器、稳压器以及AM解调器等.该芯片采用支持肖特基二极管和EEPROM的Chartered 0.35μm 2P4M CMOS工艺进行流片,读取距离大于3m,芯片面积为300μm×720μm.

  14. Mesospheric observations with the EISCAT UHF radar during polar cap absorption events: 3. Comparison with simultaneous EISCAT VHF measurements

    Directory of Open Access Journals (Sweden)

    M. T. Rietveld

    Full Text Available Mesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the first comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, co-located observations by the two radars. VHF spectra observed with a vertical antenna were found to be significantly narrower than model predictions, in agreement with earlier UHF results. For antenna pointing directions that were significantly away from the vertical, the wider VHF radar beam gave rise to broadening of the observed spectra due to vertical shears in the horizontal wind. In this configuration, UHF spectral measurements were found to be more suitable for aeronomical applications. Both radar systems provide consistent and reliable estimates of the neutral wind. Spectral results using both the multipulse and pulse-to-pulse schemes were intercompared and their suitability for application to combined mesosphere – lower thermosphere studies investigated.Key words. Mesophere · Lower thermosphere · EISCAT UHF radar · EISCAT VHF radar

  15. Recent applications of UHF-MRI in the study of human brain function and structure : a review

    NARCIS (Netherlands)

    Van der Zwaag, W.; Schäfer, Andreas; Marques, José P; Turner, R.; Trampel, Robert

    2016-01-01

    The increased availability of ultra-high-field (UHF) MRI has led to its application in a wide range of neuroimaging studies, which are showing promise in transforming fundamental approaches to human neuroscience. This review presents recent work on structural and functional brain imaging, at 7 T and

  16. Design and Analysis of High-Performance Smart Card with HF/UHF Dual-Band RFID Tag and Memory Functions

    OpenAIRE

    Gi-Hyun Hwang; Dae-Ki Kang

    2013-01-01

    In this paper, we introduce a novel design of high-performance smart card with HF/UHF dual-band RFID tag to overcome frequency interference problem. Firstly, we have designed and tested a UHF RFID tag using a simulation software system. In the smart card hardware design stage, we connect a HF antenna and a UHF antenna and place them in one inlay sheet. Using a spectrum analyzer, we systematically adjust the antenna pattern to detect the optimal patterns that fit the impedance of the RFID chip...

  17. 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

  18. Predicted coverage of a COFDM single frequency network for UHF digital terrestrial TV broadcasting

    Science.gov (United States)

    Lee, M. B. R.

    The Coded Orthogonal Frequency Division Multiplex (COFDM) transmission system provides a very high degree of tolerance towards multipath interference. Three factors contribute towards this tolerance: the inclusion of a guard interval, coding to provide error correction and the division of the digital data amongst a very large number of low bit rate carriers. It follows from this that a national network of co-channel transmitters can be developed such that not only do neighboring transmitters not cause mutual interference but can combine in a constructive manner. This is the principle of the Single Frequency Network, or SFN. Experience with Digital Audio Broadcasting (DAB) suggests that an SFN could be utilized for Digital Video Broadcasting (DVB). Such a system would make very efficient use of the available UHF channels. The Report presents the results of coverage predictions performed for a network of 128 transmitters sited at the locations of existing high and medium power UK UHF broadcast transmitters. Predictions were carried out for a range of values of guard interval, and for both directional and omnidirectional receiving antennas. Use of COFDM and the latest data compression techniques allows a High Definition Television (HDTV) program to be transmitted in a standard UHF channel. However it will require a higher-order modulation scheme than is used for DAB. This will reduce the tolerance towards noise and interference. The guard interval may therefore have to be lengthened so that signals from more distant transmitters within the network arrive within the guard interval. The results of the predictions show that the ad hoc transmitter network examined will serve 90 percent or more of the UK population, using the same guard interval as has been chosen for Mode 1 of the Eureka DAB system, provided that a directional antenna is used. The directional antenna provides most of the extra protection required against interfering signals. The same coverage can be

  19. 镁/镀锌钢异种合金单、双光束激光熔钎焊特性%Single and dual beam laser welding-brazing characteristics of magnesium/zinc-coated steel dissimilar alloys

    Institute of Scientific and Technical Information of China (English)

    檀财旺; 梅长兴; 李俐群; 戴景民; 郭伟

    2012-01-01

    以镁焊丝为填充材料,对镁/镀锌钢异种合金进行单、双光束激光熔钎焊试验研究,分析不同工艺参数对焊缝成形的影响规律,获得不同热源作用方式下的界面形态规律及其对界面强度的影响.结果表明:采用单、双光束进行填丝熔钎焊均可获得较满意的外观成形:单光束容易存在未钎合现象,焊接过程不够稳定,而双光束具有更好的温度分布,容易提高润湿铺展能力.剪切强度测试结果表明,单、双光束最大的接头效率分别达到30.9%和42.4%,焊趾处裂纹的存在是导致接头失效的主要原因.%The single and dual laser welding-brazing of AZ31 Mg alloy to DP980 galvanized steel was conducted with Mg filler wire. The effect of different parameters on the weld appearance was analyzed. Moreover, the interfacial pattern under different heat sources and its influence on the interfacial strength were obtained. The results indicate that good weld appearance can be achieved using both single and dual laser beam welding-brazing as filler wire. It tends to produce the lack of fusion defect by single-beam welding and the welding process is unstable. The dual-beam welding has much more uniform temperature distribution, so, the spreading-wetting ability is better than the former. The shear test results show that the highest joint efficiency of single-beam and dual-beam welding are 30.9% and 42.4%, respectively. The crack produced at the toe of weld after laser welding-brazing is the main reason for joint failure.

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

    Science.gov (United States)

    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

  1. 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.

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

    Science.gov (United States)

    Swanson, Alan; Huang, Shengli; Crabtree, Robert

    2009-01-01

    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.

  3. A dynamic spectrum analysis solution for the characterization of the UHF spectrum

    Science.gov (United States)

    Pooler, Richard K.; Narayanan, Ram M.; Sherbondy, Kelly D.; Martone, Anthony F.; Gallagher, Kyle A.

    2016-05-01

    The Spectral Analysis Solution (SAS), under development, is a multichannel superheterodyne signal analyzer with the intended applications of radio frequency (RF) research, radar verification, and general purpose spectrum sensing, primarily in the ultra-wideband (UWB) range from ultra high frequency (UHF) to the S-band. The SAS features a wideband channel operating from 100 kHz to 1.8 GHz and eight narrowband channels having adjustable instantaneous bandwidths ranging from 1 MHz to 100 MHz. The wideband channel provides a large picture of the RF spectrum while the narrowband channels allow for high resolution, low noise floor, and high spurious free dynamic range (SFDR) capabilities. An adaptive graphic user interface (GUI) has been implemented for the system that actively pulls and processes the system data in real time. This paper outlines the motivation and theory behind the system along with system validation and implementation results.

  4. Object Motion Detection System Using Passive UHF RFID Technology For A Trauma Bay

    Directory of Open Access Journals (Sweden)

    Young Ho Lee

    2015-08-01

    Full Text Available There has been demands of context-aware systems in a hospital domain and several types of sensors have been applied as sources of medical activities. Unlike the previous passive RFID use of simply identifying objects this paper presents a system for motion detection of medical objects in a trauma bay by ranging the received signal strength indication RSSI using UHF passive RFID tags as one of those sensors that provide information on medical activities. To use passive RFID RSSI for motion detection Three different types of RSSI estimators are evaluated to process noisy RSSI and the adaptive threshold is proposed in the system to improve the resolution of detecting motion. Our system has been tested with recorded RSSI values in a laboratory and an actual trauma bay during simulated resuscitations performed by trauma teams. The proposed system has achieved 85.9 - 92.1 accuracies for most passive items that are used in a trauma bay.

  5. A novel technology for motion capture using passive UHF RFID tags.

    Science.gov (United States)

    Krigslund, R; Dosen, S; Popovski, P; Dideriksen, J L; Pedersen, G F; Farina, D

    2013-05-01

    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) tags placed on the body segments whose kinematics is to be captured. Dual polarized antennas are used to estimate the inclination of each tag based on the polarization of the tag responses. The method has been validated experimentally for the shank and thigh in the sagittal plane during treadmill walking. The reference segment 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.

  6. An Ultra-Low-Power Oscillator with Temperature and Process Compensation for UHF RFID Transponder

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2013-06-01

    Full Text Available This paper presents a 1.28MHz ultra-low-power oscillator with temperature and process compensation. It is very suitable for clock generation circuits used in ultra-high-frequency (UHF radio-frequency identification (RFID transponders. Detailed analysis of the oscillator design, including process and temperature compensation techniques are discussed. The circuit is designed using TSMC 0.18μm standard CMOS process and simulated with Spectre. Simulation results show that, without post-fabrication calibration or off-chip components, less than ±3% frequency variation is obtained from –40 to 85°C in three different process corners. Monte Carlo simulations have also been performed, and demonstrate a 3σ deviation of about 6%. The power for the proposed circuitry is only 1.18µW at 27°C.

  7. 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.

  8. Passive UHF RFID Tags with Specific Printed Antennas for Dielectric and Metallic Objects Applications

    Directory of Open Access Journals (Sweden)

    K. Siakavara

    2017-09-01

    Full Text Available Design process and respective results for the synthesis of specific Radiofrequency Identification(RFID tag antennas, suitable for dielectric and metallic objects, are presented. The antennas were designed for the UHF(865MHz-869MHz band and their basic configuration is that of the printed spiral type. Six modification steps to the classical spiral layout are proposed and it was proved that they can lead to tags with high readability and reading distances up to 10m when designed for dielectric object and up to 7m in the case of metallic objects. The results of the measurements of the fabricated tags are explained via theoretical evaluations which take into account reflection phenomena, that are present in a real environment at which the tags are used.

  9. Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags

    Science.gov (United States)

    Rokunuzzaman, Md.; Islam, Mohammad Tariqul; Arshad, Haslina; Jit Singh, Mandeep; Misran, Norbahiah

    2015-01-01

    This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network. The square loop dimensions are modified to reach a conjugate impedance matching. A gap is fixed between the feed-lines to link the chip. To achieve impedance matching, the structures of the feed-line are optimized accordingly. In addition, the antenna consists of a straightforward geometry. An 11.9-meter maximum read range is achieved using a compact size of 80 × 44 mm2 and 3.2 W for the effective isotropic radiated power. Additional findings reveal that the proposed tag antenna is able to provide a stable resonance response in the near field of a large metallic surface. PMID:26177376

  10. Extended post processing for simulation results of FEM synthesized UHF-RFID transponder antennas

    Directory of Open Access Journals (Sweden)

    R. Herschmann

    2007-06-01

    Full Text Available The computer aided design process of sophisticated UHF-RFID transponder antennas requires the application of reliable simulation software. This paper describes a Matlab implemented extension of the post processor capabilities of the commercially available three dimensional field simulation programme Ansoft HFSS to compute an accurate solution of the antenna's surface current distribution. The accuracy of the simulated surface currents, which are physically related to the impedance at the feeding point of the antenna, depends on the convergence of the electromagnetic fields inside the simulation volume. The introduced method estimates the overall quality of the simulation results by combining the surface currents with the electromagnetic fields extracted from the field solution of Ansoft HFSS.

  11. Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags.

    Directory of Open Access Journals (Sweden)

    Md Rokunuzzaman

    Full Text Available This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network. The square loop dimensions are modified to reach a conjugate impedance matching. A gap is fixed between the feed-lines to link the chip. To achieve impedance matching, the structures of the feed-line are optimized accordingly. In addition, the antenna consists of a straightforward geometry. An 11.9-meter maximum read range is achieved using a compact size of 80 × 44 mm2 and 3.2 W for the effective isotropic radiated power. Additional findings reveal that the proposed tag antenna is able to provide a stable resonance response in the near field of a large metallic surface.

  12. Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags.

    Science.gov (United States)

    Rokunuzzaman, Md; Islam, Mohammad Tariqul; Arshad, Haslina; Jit Singh, Mandeep; Misran, Norbahiah

    2015-01-01

    This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network. The square loop dimensions are modified to reach a conjugate impedance matching. A gap is fixed between the feed-lines to link the chip. To achieve impedance matching, the structures of the feed-line are optimized accordingly. In addition, the antenna consists of a straightforward geometry. An 11.9-meter maximum read range is achieved using a compact size of 80 × 44 mm2 and 3.2 W for the effective isotropic radiated power. Additional findings reveal that the proposed tag antenna is able to provide a stable resonance response in the near field of a large metallic surface.

  13. 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.

  14. 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

  15. Automorphisms of the UHF algebra that do not extend to the Cuntz algebra

    CERN Document Server

    Conti, Roberto

    2010-01-01

    Automorphisms of the canonical core UHF-subalgebra F_n of the Cuntz algebra O_n do not necessarily extend to automorphisms of O_n. Simple examples are discussed within the family of infinite tensor products of (inner) automorphisms of the matrix algebras M_n. In that case, necessary and sufficient conditions for the extension property are presented. It is also addressed the problem of extending to O_n the automorphisms of the diagonal D_n, which is a regular MASA with Cantor spectrum. In particular, it is shown the existence of product-type automorphisms of D_n that are not extensible to (possibly proper) endomorphisms of O_n.

  16. Long range ultra-high frequency (UHF) radio frequency identification (RFID) antenna design

    Science.gov (United States)

    Reynolds, Nathan D.

    There is an ever-increasing demand for radio frequency identification (RFID) tags that are passive, long range, and mountable on multiple surfaces. Currently, RFID technology is utilized in numerous applications such as supply chain management, access control, and public transportation. With the combination of sensory systems in recent years, the applications of RFID technology have been extended beyond tracking and identifying. This extension includes applications such as environmental monitoring and healthcare applications. The available sensory systems usually operate in the medium or high frequency bands and have a low read range. However, the range limitations of these systems are being overcome by the development of RFID sensors focused on utilizing tags in the ultra-high frequency (UHF) band. Generally, RFID tags have to be mounted to the object that is being identified. Often the objects requiring identification are metallic. The inherent properties of metallic objects have substantial effects on nearby electromagnetic radiation; therefore, the operation of the tag antenna is affected when mounted on a metallic surface. This outlines one of the most challenging problems for RFID systems today: the optimization of tag antenna performance in a complex environment. In this research, a novel UHF RFID tag antenna, which has a low profile, long range, and is mountable on metallic surfaces, is designed analytically and simulated using a 3-D electromagnetic simulator, ANSYS HFSS. A microstrip patch antenna is selected as the antenna structure, as patch antennas are low profile and suitable for mounting on metallic surfaces. Matching and theoretical models of the microstrip patch antenna are investigated. Once matching and theory of a microstrip patch antenna is thoroughly understood, a unique design technique using electromagnetic band gap (EBG) structures is explored. This research shows that the utilization of an EBG structure in the patch antenna design yields

  17. Meteor head echo polarization at 930 MHz studied with the EISCAT UHF HPLA radar

    Directory of Open Access Journals (Sweden)

    G. Wannberg

    2011-06-01

    Full Text Available The polarization characteristics of 930-MHz meteor head echoes have been studied for the first time, using data obtained in a series of radar measurements carried out with the tristatic EISCAT UHF high power, large aperture (HPLA radar system in October 2009. An analysis of 44 tri-static head echo events shows that the polarization of the echo signal recorded by the Kiruna receiver often fluctuates strongly on time scales of tens of microseconds, illustrating that the scattering process is essentially stochastic. On longer timescales (> milliseconds, more than 90 % of the recorded events show an average polarization signature that is independent of meteor direction of arrival and echo strength and equal to that of an incoherent-scatter return from underdense plasma filling the tristatic observation volume. This shows that the head echo plasma targets scatter isotropically, which in turn implies that they are much smaller than the 33-cm wavelength and close to spherically symmetric, in very good agreement with results from a previous EISCAT UHF study of the head echo RCS/meteor angle-of-incidence relationship.

    Significant polarization is present in only three events with unique target trajectories. These all show a larger effective target cross section transverse to the trajectory than parallel to it. We propose that the observed polarization may be a signature of a transverse charge separation plasma resonance in the region immediately behind the meteor head, similar to the resonance effects previously discussed in connection with meteor trail echoes by Herlofson, Billam and Browne, Jones and Jones and others.

  18. Blind Separation Algorithm for UHF RFID Tags Data%超高频射频识别标签数据盲分离算法

    Institute of Scientific and Technical Information of China (English)

    栗华; 王洪君; 刘琚

    2011-01-01

    提出了一种新的基于ICA的超高频(Ultra high frequency,UHF)射频识别(Radio frequency identification,RFID)多标签混合数据盲分离算法.在分析UHF RFID系统链路传输模型、标签数据编码规则以及多天线RFID系统模型的基础上,得出UHF RFID多标签混合数据符合ICA算法要求的结论,并利用FastICA算法对UHFRFID仿真数据进行了盲分离,定量分析了算法的分离效果及抗噪声性能.实验结果表明,利用ICA技术对多标签混合数据进行盲分离可获得良好的效果.这为将盲分离技术应用于UHF RFID系统标签防碰撞算法奠定了良好的理论和实验依据.%A new ICA-based UHF RFID multi-tag hybrid data blind separation algorithm is presented. Based on the analysis of RFID system communication link model, tag data encoding rule and multi-antenna RFID system model, it is concluded that UHF RFID multi-tag hybrid data meets the requirements of ICA algorithm. The blind separation is calculated by using Fas-tICA algorithm for simulation data of UHF RFID tags data. The separation effect and anti-noise performance of this algorithm is analyzed quantitatively. Experimental results show that perfect results can be obtained in multi-tag hybrid data blind separation by using ICA techniques. A good theoretical and experimental basis of applying blind separation to UHF RFID tag anti-collision algorithm has been established.

  19. 一种基于方向调制的双波束扩频安全通信系统%A Dual-beam Spread Spectrum Signal Based on Directional Modulation for Secure Communication

    Institute of Scientific and Technical Information of China (English)

    洪涛; 宋茂忠; 刘渝

    2011-01-01

    A dual-beam spread spectrum signal based on directional modulation is proposed to increase the difficulty of the wireless communication tapping. The transmitted signal is not only associated with the spread spectrum sequence but also with the azimuth angle of the receiver. Therefore, this signal is a space spread spectrum signal modulated by the azimuth angle. Simulation results show that the proposed signal offers a safety method for the data transmission compared with the traditional spread spectrum signal.%为了提高通信信息在无线传输过程中的窃听难度,该文提出了一种基于方向调制的双波束扩频信号.发射信号不仅与使用的扩频序列有关,而且与接收机相对于发射机的空间方位信息有关,是一种扩频序列和空间方位信息共同调制的空间扩频信号.仿真结果表明相比于传统的扩频信号,双波束方向调制扩频信号为通信信息在信息传输层面上提供了一种更加安全的无线传输方法.

  20. UHF RFID技术在医药物流管理中的应用研究%ON APPLYING UHF RFID TECHNOLOGY TO MEDICINE LOGISTICS MANAGEMENT

    Institute of Scientific and Technical Information of China (English)

    桑世庆

    2013-01-01

    Combining with wireless internet of things technology, the contactless data acquisition technology achieved with radio frequency communication is put into fullplay in identifying and recording the pharmaceuticals in logistics distribution in order to enhance its efficiency and accuracy. An idea of using RFID technology to manage the medicien warehousing process is proposed in this paper in combination with the speciality of medicine logistics warehouse management, which realises the application of UHF band-based RFID technology in existing storage centre system, ensures data integrity, optimises internal business processes and enhances the agility of distribution centre as well as the information level of logistics centre.%结合无线物联网技术,充分利用射频通信实现的非接触式数据采集技术对物流配送中的药品进行识别记录,以提高物流配送的效率和准确度.结合医药物流仓储管理的特殊性,提出应用RFID技术对医药仓储过程进行管理,实现使用基于UHF频段的RFID技术在仓储中心现有系统的应用,保证数据的完整性,优化内部业务流程,提高了配送中心的敏捷化及物流中心的信息化层次.

  1. UHF RFID location algorithm based on dual frequency subcarriers amplitude modulation%双频副载波调幅的UHF RFID定位研究

    Institute of Scientific and Technical Information of China (English)

    史伟光; 刘开华; 房静静; 罗蓬; 于洁潇; 黄翔东

    2012-01-01

    For the accuracy of indoor location system based on the strength of received signal being restricted by the multipath effect and non line of sight propagation,a location algorithm using radio frequency identification was proposed which was suitable for 915 MHZ UHF signal.Dual frequency subcarriers were introduced to overcome the ambiguity of whole cycles and reduce the demands of sample rate.On the basis of spectrum analysis of All-Phase FFT,a mechanism was put forward to estimate the phase difference so as to achieve the ranging information with under-sampling,and then the position of the tracking tags could be obtained by the least square method.Simulation results show that,the proposed algorithm possesses a higher accuracy and stability.%针对多径效应及非视距阻挡使得基于收信强度的室内定位系统精度难以进一步提高的问题,提出了一种适于915 MHZ射频识别定位算法,以收发信号的相位差作为定位依据,引入双频副载波克服整周期模糊度并降低采样率要求,结合全相位FFT谱分析特性,提出一种基于欠采样条件下的相位差估计方法并获取测距信息,利用最小二乘法求解定位标签位置.仿真结果表明,该算法具有良好的定位准确度及稳定性.

  2. Mobile satellite system fade statistics for shadowing and multipath from roadside trees at UHF and L-band

    Science.gov (United States)

    Goldhirsh, Julius; Vogel, Wolfhard J.

    1989-01-01

    Field tests related to planned mobile satellite systems were performed, and results that add to the existing database of propagation measurements at L-band (1.5 GHz) are described. They are considered particularly useful in that propagation effects were studied systematically, with repeated and controlled runs pertaining to different path elevation angles, road types, and path geometries defining shadowing and line-of-sight modes. In addition, simultaneous L-band and UHF measurements were performed for the purpose of establishing scaling factors applicable to previous UHF (870 MHz) results. The control of the experimental parameters was made possible by using a helicopter as the source platform and a mobile van to house the receiver.

  3. Studies of polar mesosphere summer echoes with the EISCAT VHF and UHF radars: Information contained in the spectral shape

    Science.gov (United States)

    Strelnikova, Irina; Rapp, Markus

    2010-01-01

    The nature of PMSE in the VHF and UHF frequency range is considered taking into account the shape of corresponding Doppler spectra. Assuming a turbulence-based model of PMSE it is argued that for cases where a VHF radar detects strong PMSE, the UHF radar could either detect enhanced coherent scattering caused by the same physical process as in the VHF (i.e., turbulence with large charged ice particles), there could be incoherent scattering modified by the charged ice particles, or there could be a mixture of both. In order to distinguish these cases a simple but robust method is introduced to characterize the shape of the Doppler spectra derived from observations at both frequencies. Spectral shapes are quantified with one simple fitting parameter of a generalized fit to the autocorrelation function (=Fourier transform of the Doppler spectrum). This parameter takes a value of 1 for a Lorentzian spectrum indicative of pure incoherent scatter from the D-region, a value of 2 for coherent scatter owing to turbulence, and a value of less than 1 for incoherent scatter modified by the presence of charged aerosol particles. This method is applicable to observations at altitudes between ˜70 and ˜90 km. Simultaneous observations with the EISCAT VHF and UHF radar are presented in which all three cases mentioned above are identified. For the case of incoherent scatter modified by the presence of charged aerosol particles we quantify the radius of the involved ice particles to exceed ˜5 nm. Most importantly, however, for the case where the UHF-signal exceeded the incoherent scatter signal significantly, the spectrum revealed a clear Gaussian shape indicative of a coherent scattering process with identical spectral width as for the VHF-observations. This finding gives strong support that both echoes are created by the same turbulence-based mechanism and not by different mechanisms as speculated by several previous authors.

  4. Disordered redox metabolism of brain cells in rats exposed to low doses of ionizing radiation or UHF electromagnetic radiation.

    Science.gov (United States)

    Burlaka, A P; Druzhyna, M O; Vovk, A V; Lukin, S М

    2016-12-01

    To investigate the changes of redox-state of mammalian brain cells as the critical factor of initiation and formation of radiation damage of biological structures in setting of continuous exposure to low doses of ionizing radiation or fractionated ultra high frequency electromagnetic radiation (UHF EMR) at non-thermal levels. The influence of low-intensity ionizing radiation was studied on outbred female rats kept for 1.5 years in the Chernobyl accident zone. The effects of total EMR in the UHF band of non-thermal spectrum were investigated on Wistar rats. The rate of formation of superoxide radicals and the rate of NO synthesis in mitochondria were determined by the EPR. After exposure to ionizing or UHF radiation, the levels of ubisemiquinone in brain tissue of rats decreased by 3 and 1.8 times, respectively. The content of NO-FeS-protein complexes in both groups increased significantly (р < 0.05). In the conditions of ionizing or EMR the rates of superoxide radical generation in electron-transport chain of brain cell mitochondria increased by 1.5- and 2-fold, respectively (р < 0.05). In brain tissue of rats kept in the Chernobyl zone, significant increase of NO content was registered; similar effect was observed in rats treated with UHFR (р < 0.05). The detected changes in the electron transport chain of mitochondria of brain cells upon low-intensity irradiation or UHF EMR cause the metabolic reprogramming of cell mitochondria that increases the rate of superoxide radical generation and nitric oxide, which may initiate the development of neurodegenerative diseases and cancer. This article is part of a Special Issue entitled "The Chornobyl Nuclear Accident: Thirty Years After".

  5. Analyse und Verhaltensmodellierung des HF-Frontends von passiven CMOS-Transpondern für UHF-RFID-Anwendungen

    OpenAIRE

    Seemann, Kay

    2007-01-01

    In dieser Arbeit werden neuartige Methoden für den systematischen Entwurf, die dynamische nichtlineare Verhaltensmodellierung und die On-Wafer-Charakterisierung des HF-Frontends von passiven CMOS-Transpondern für UHF-RFID-Anwendungen vorgestellt. Außerdem wird eine optimierte Frontend-Realisierung in einer 140-nm-CMOS-Technologie präsentiert und analysiert. In der gezeigten Realisierung werden nichtlineare Substrateffekte des Begrenzungs- und Rückstreuelements zur Leistungsgleichrichtung genu...

  6. 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.

  7. 一种新型无源UHF RFID带隙基准电路%New type bandgap reference for UHF RFID tag

    Institute of Scientific and Technical Information of China (English)

    杜永乾; 庄奕琪; 李小明; 景鑫; 戴力

    2013-01-01

    设计了一种适用于无源超高频射频识别芯片的电流模带隙基准电路,其中负温度系数电流利用BJT管的基射极电压的负温度特性产生,正温度系数电流利用偏置在亚阈值区的MOS器件其漏源电流与栅源电压呈指数关系的特性产生.该基准电路采用TSMC 0.18μm工艺库仿真并投片验证,基准电压的绝对值偏差最大不超过1.75%.测试结果表明,该电路功耗仅为0.65 μW,最低工作电压为0.829V,温度系数为±63×10-6/℃,芯片有效面积为0.04 mm2.该基准电路已成功应用于一款无源超高频射频识别芯片中,其读取灵敏度为-16 dBm.%A novel low-voltage, low-power current mode bandgap reference circuit for the passive UHF RFID tag is presented. The ICTAT current is generated by VBE of the BJT transistor. The 1PTAT current is generated by the MOSFET biased in the sub-threshold region, based on the theory that the I-V curve of the sub-threshold MOSFET shows an exponential relationship. The circuit is designed and implemented by TSMC 0. 18 μm CMOS technology. The biggest variation of Vref of the reference is smaller than 1. 75% . Test results show that the power of the circuit is 0. 65μW, and that the minimum operating voltage is 0. 829 V. The active area of the circuit is about 0. 04 mm2. As a result, the read sensitivity of the tag with the proposed bandgap reference circuit is — 16dBm.

  8. 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.

  9. The GALEX Arecibo SDSS Survey. VIII. Final Data Release -- The Effect of Group Environment on the Gas Content of Massive Galaxies

    CERN Document Server

    Catinella, Barbara; Cortese, Luca; Fabello, Silvia; Hummels, Cameron B; Moran, Sean M; Lemonias, Jenna J; Cooper, Andrew P; Wu, Ronin; Heckman, Timothy M; Wang, Jing

    2013-01-01

    We present the final data release from the GALEX Arecibo SDSS Survey (GASS), a large Arecibo program that measured the HI properties for an unbiased sample of ~800 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025Arecibo observations for 250 galaxies. We use the full GASS sample to investigate environmental effects on the cold gas content of massive galaxies at fixed stellar mass. The environment is characterized in terms of dark matter halo mass, obtained by cross-matching our sample with the SDSS group catalog of Yang et al. Our analysis provides, for the first time, clear statistical evidence that massive galaxies located in halos with masses of 10^13-10^14 Msun have at least 0.4 dex less HI than objects in lower density environments. The process responsible for the suppression of gas in group galaxies most likely drives the observed quenching of the star formation in these systems. Our findings strongly support the importance of the group env...

  10. 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.

  11. The Monte Carlo Simulation of Tsinghua Homo-Source Dual-Beam Medical Accelerator%清华同源双束医用加速器蒙特卡罗模拟

    Institute of Scientific and Technical Information of China (English)

    马悦; 吴朝霞; 王石; 刘亚强

    2011-01-01

    Objective: To apply Monte Carlo method in simulating the Homo-Source Dual-Beam medical accelerator developed by Tsinghua University and lay the foundation for future researches on the Accelerator' s KV energy dose distribution in an image-guided radiotherapy procedure. Methods: (1)Using Monte Carlo's BEAMnrc program for simulating the head of Tsinghua Homo-Source Dual-Beam Medical Accelerator we obtained the Phase Space file which would be used as the source for the next step. (2) Using Monte Carlo' s DOSXYZnre program we calculated the percent depth dose (PDD) and off axis ratio (OAR), dealt the dose data by MATLAB program and displayed them in EXCEL. (3) Analyzed the impact of the Monte Carlo simulated parameters on the final outcome was analyzed. (4)Compared the PDD and OAR calculated with the measured of identical condition. Results: The PDD and OAR in water phantom simulated using Monte Carlo method were well matched with those measured in the actual experiments and the Accelerator' s Monte Carlo model was achieved. Conclusions: The Accelerator's Monte Carlo simulated parameters of KV energy are apparently different from that of High-energy. To obtain the accurate Accelerator's Monte Carlo model, it is important to choose proper electron beam energy and electron space density distribution. The Accelerator's Monte Carlo model can be used in future researches on the image dose distribution.%目的:使用蒙特卡罗方法模拟清华大学自主研制的同源双束医用加速器,为今后研究该设备KV级能量在放射治疗中成像剂量分布奠定基础.方法:(1)借助蒙卡BEAMnrc程序模拟加速器机头得到相空间文件.(2)以该相空间文件为源,使用蒙卡DOSXYZnrc程序计算水模体中百分深度剂量(percent depth dose,PDD)和离轴比(off axis ratio,OAR),采用MATLAB编程提取剂量数据显示于EXCEL.(3)分析蒙卡模拟参数对结果的影响.(4)对比实测调整模拟参数.结果:蒙卡模拟所得水模体中PDD

  12. El uso de fotocélulas de haz simple y doble para medir la velocidad en carreras®. The use of single- and dual-beam photocells to measure the sprint time®.

    Directory of Open Access Journals (Sweden)

    Juan García-López

    2012-10-01

    Full Text Available ResuemnEl objetivo del estudio fue analizar la influencia de la tecnología de las fotocélulas en el registro de tiempo y su fiabilidad durante de carreras de velocidad de corta distancia. Participaron 25 estudiantes (20.5±0.5 años; 1.78±0.02 m; 77.5±1.8 kg que fueron evaluados en 3 días (2 de familiarización y 1 de test. Se registraron aleatoriamente 3 carreras de aceleración y 3 velocidad lanzada, cronometradas simultáneamente a los 5, 10 y 15 m por dos sistemas de fotocélulas DSD Laser System®: haz simple y doble haz. El tipo de fotocélulas utilizadas influyó en el tiempo de carrera (F=11.92 y p 0.80 a los 10 y 5 m, respectivamente. En la carrera lanzada ambos sistemas midieron prácticamente igual (diferencias de ~0.005 s, obteniendo registros fiables a los 15 y 10 m, respectivamente. En conclusión, en carreras de aceleración la distancia mínima a registrar con haz simple debe ser de 10 m, y de 5 m con haz doble, mientras que en carreras lanzadas deberían utilizarse unas distancias mínimas de 15 y 10 m, respectivamente. Futuros estudios deberían analizar la distancia óptima a la primera fotocélula en las carreras de aceleración, para aumentar la fiabilidad de la medición y facilitar la comparación entre registros de diferentes estudios.AbstractThe purpose was to analyze the influence of the timing gates’ technology on both running time performance and its reliability during short sprint distances. Twenty-five physical students participated (20.5±0.5 yr; 1.78±0.02 m; 77.5±1.8 kg, whose were evaluated during 3 separate days (2 familiarization sessions and 1 testing session. Three standing-start and 3 flying-start runs were randomized and simultaneously registered at 5, 10 and 15 m by two timing gates DSD Laser System®: single- and dual-beam. The type of timing gates affected the performance (F=11.92 y p0.80 at the distances of 10 and 5 m, respectively. During the flying-start runs, both systems obtained a very

  13. Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry.

    Science.gov (United States)

    Rana, Namrata; McLean, Samantha; Mann, Brian E; Poole, Robert K

    2014-12-01

    Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, O.N.; Lawson, J.Q.

    1977-01-01

    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.

  15. Design und Analyse elektrisch kleiner Antennen für den Einsatz in UHF RFID Transpondern

    Directory of Open Access Journals (Sweden)

    R. Herschmann

    2006-01-01

    Full Text Available RFID Systeme werden seit Anfang der neunziger Jahre mit stetig zunehmender Verbreitung im Bereich der automatischen Produktidentifikation, der Diebstahlsicherung (EAS, Electronic Article Surveillance und für automatische Zutrittskontrollsysteme eingesetzt. Objekte werden hierzu mit einem Transponder ausgestattet, der aus einer Antenne und einem Chip auf einem Trägermaterial besteht. Von großem Interesse ist die Entwicklung und Optimierung von passiven Transpondern für den Einsatz in UHF RFID Systemen. Diese Transponder beziehen die Energie zum Betrieb des Chips aus dem elektromagnetischen Feld einer Schreib-Leseeinheit. Hierfür ist neben der Anpassung der Eingangsimpedanz der Antenne an die Chipimpedanz auch eine möglichst hohe Bandbreite der Antennen wünschenswert, um die Funktion des Transponders bei Schwankungen der Chipimpedanz und variablen Umgebungsparametern zu gewährleisten. Der aus Platzgründen notwendige Einsatz elektrisch kleiner Antennen bedingt eine möglichst optimale Ausnutzung der zur Verfügung stehenden Fläche auf dem Trägermaterial zur Aufnahme der Antenne. Die vorliegende Arbeit beschreibt ein Verfahren zur Analyse und Synthese neuartiger Antennendesigns auf der Basis parametrisierter meandrierter, spiralförmiger und logarithmisch periodischer Dipole.

  16. 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.

  17. Printed UHF RFID antennas with high efficiencies using nano-particle silver ink.

    Science.gov (United States)

    Lee, Yongshik; Kim, Chung Hwan; Shin, Dong-Youn; Kim, Young Gook

    2011-07-01

    One of the most popular targets of conductive ink technology is to print RFID tag antennas. However, the printed RFID antennas, manufactured by conductive silver ink which is generally based on microsized silver particles, have lower conductivity and consequently lower radiation efficiency than those by conventional copper etching method. This work demonstrates nano-particle conductive silver ink that is capable of printing UHF RFID antennas with improved radiation efficiency. Compared with commercial micro-particle silver ink, the solid content of metal is much higher in the proposed nanoparticle silver ink, leading to better electrical properties. Two types of dipole antennas are printed with the proposed nano-particle as well as with commercial micro-particle inks. Also, the same antennas are fabricated by copper etching. With these conductive inks, a straight and a meandered dipole antennas are fabricated and their radiation efficiencies are measured with the Wheeler cap method. Experimental results show that the radiation efficiencies of the antennas based on nanoparticle silver ink are superior to those printed with the micro-particle silver ink, and are comparable to those of popular copper antennas.

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

    Science.gov (United States)

    Jinpeng, Shen; Xin'an, Wang; Shan, Liu; Hongqiang, Zong; Jinfeng, Huang; Xin, Yang; Xiaoxing, Feng; Binjie, Ge

    2012-11-01

    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.

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

    Institute of Scientific and Technical Information of China (English)

    Shen Jinpeng; Wang Xin'an; Liu Shan; Zong Hongqiang; Huang Jinfeng; Yang Xin; Feng Xiaoxing; Ge Binjie

    2012-01-01

    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.

  20. Fully Integrated Passive UHF RFID Tag for Hash-Based Mutual Authentication Protocol

    Directory of Open Access Journals (Sweden)

    Shugo Mikami

    2015-01-01

    Full Text Available Passive radio-frequency identification (RFID tag has been used in many applications. While the RFID market is expected to grow, concerns about security and privacy of the RFID tag should be overcome for the future use. To overcome these issues, privacy-preserving authentication protocols based on cryptographic algorithms have been designed. However, to the best of our knowledge, evaluation of the whole tag, which includes an antenna, an analog front end, and a digital processing block, that runs authentication protocols has not been studied. In this paper, we present an implementation and evaluation of a fully integrated passive UHF RFID tag that runs a privacy-preserving mutual authentication protocol based on a hash function. We design a single chip including the analog front end and the digital processing block. We select a lightweight hash function supporting 80-bit security strength and a standard hash function supporting 128-bit security strength. We show that when the lightweight hash function is used, the tag completes the protocol with a reader-tag distance of 10 cm. Similarly, when the standard hash function is used, the tag completes the protocol with the distance of 8.5 cm. We discuss the impact of the peak power consumption of the tag on the distance of the tag due to the hash function.

  1. 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

  2. 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.

  3. UHF RiverSonde observations of water surface velocity at Threemile Slough, California

    Science.gov (United States)

    Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.; Ruhl, C.A.

    2005-01-01

    A UHF RiverSonde system, operating near 350 MHz, has been in operation at Threemile Slough in central California, USA since September 2004. The water in the slough is dominated by tidal effects, with flow reversals four times a day and a peak velocity of about 0.8 m/s in each direction. Water level and water velocity are continually measured by the U. S. Geological Survey at the experiment site. The velocity is measured every 15 minutes by an ultrasonic velocity meter (UVM) which determines the water velocity from two-way acoustic propagation time-difference measurements made across the channel. The RiverSonde also measures surface velocity every 15 minutes using radar resonant backscatter techniques. Velocity and water level data are retrieved through a radio data link and a wideband internet connection. Over a period of several months, the radar-derived mean surface velocity has been very highly correlated with the UVM index velocity several meters below the surface, with a coefficient of determination R2 of 0.976 and an RMS difference of less than 10 cm/s. The wind has a small but measurable effect on the velocities measured by both instruments. In addition to the mean surface velocity across the channel, the RiverSonde system provides an estimate of the cross-channel variation of the surface velocity. ?? 2005 IEEE.

  4. Statistics of Convective Cores Using ARM UHF Wind Profilers During the Oklahoma MC3E Campaign

    Science.gov (United States)

    Giangrande, S.; Dulaney, N.; Collis, S. M.; Jensen, M. P.

    2011-12-01

    Measurements of vertical velocity and associated deep convective storm characteristics are observations of high priority for climate modelers. As part of an overall effort to improve our understanding of precipitating systems, the ARM Climate Research Facility (ACRF) in Oklahoma recently reconfigured its existing 915 MHz wind profilers to operate in vertically-pointing modes for the sampling through deep convective storms. Unique UHF profiler modes were designed to allow these radar systems to act as anchors for ARM scanning radar observations as well as to evaluate the errors for scanning radar retrievals. The first demonstration of these reconfigured profiler systems took place during the Midlatitude Convective Clouds and Storms Experiment (MC3E). In this study, we explore the properties of convective updraft and downdraft core properties as revealed by standalone ARM profilers using standard definitions for diameter, intensity and mass flux. Observations are obtained under the umbrella of the ACRF scanning radar facilities that will provide additional insight and guidance for storm intensity, hydrometeor contributions to fall speed and storm translational motion.

  5. Coplanar UHF RFID tag antenna with U-shaped inductively coupled feed for metallic applications.

    Science.gov (United States)

    Salman, Karrar Naji; Ismail, Alyani; Raja Abdullah, Raja Syamsul Azmir; Saeedi, Tale

    2017-01-01

    In this paper, we present a novel compact, coplanar, tag antenna design for metallic objects. Electrically small antenna has designed for a UHF RFID (860-960 MHz) based on a proximity-coupled feed through. Furthermore, two symmetrical Via-loaded coplanar grounds fed by a U-shaped inductively coupled feed through an embedded transmission line. This configuration results in an antenna with dimensions of 31 × 19.5 × 3.065 mm3 at 915 MHz, and the total gain for the antenna is 0.12 dBi. The Via-loaded coplanar and U-shaped inductively coupled feeds allow the antenna to provide flexible tuning in terms of antenna impedance. In addition, a figure of merit is applied for the proposed tag antenna, and the results are presented. The read range is measured to be 4.2 m, which is very close to simulated values. This antenna measurement shows very good agreement with simulations.

  6. Multiport Circular Polarized RFID-Tag Antenna for UHF Sensor Applications.

    Science.gov (United States)

    Zaid, Jamal; Abdulhadi, Abdulhadi; Kesavan, Arun; Belaizi, Yassin; Denidni, Tayeb A

    2017-07-05

    A circular polarized patch antenna for UHF RFID tag-based sensor applications is presented, with the circular polarization (CP) generated by a new antenna shape, an asymmetric stars shaped slotted microstrip patch antenna (CP-ASSSMP). Four stars etched on the patch allow the antenna's size to be reduced by close to 20%. The proposed antenna is matched with two RFID chips via inductive-loop matching. The first chip is connected to a resistive sensor and acts as a sensor node, and the second is used as a reference node. The proposed antenna is used for two targets, serving as both reference and sensor simultaneously, thereby eliminating the need for a second antenna. Its reader can read the RFID chips at any orientation of the tag due to the CP. The measured reading range is about 25 m with mismatch polarization. The operating frequency band is 902-929 MHz for the two ports, which is covered by the US RFID band, and the axial-ratio bandwidth is about 7 MHz. In addition, the reader can also detect temperature, based on the minimum difference in the power required by the reference and sensor.

  7. 超高频在线监测技术在 GIS 局部放电检测中的应用%The Application of Online Monitoring Technique with UHF to Detection of the GIS Partial Discharge

    Institute of Scientific and Technical Information of China (English)

    黄凤萍; 刘开贵

    2013-01-01

      鉴于超高频(UHF)法用于局部放电检测日渐增多,结合 UHF 用于广东电网变电站 GIS 局部放电检测案例,分析了 UHF 在线监测技术的优越性,并对 PDM UHF 局部放电在线监测系统的应用效果进行了试验研究。试验和实践表明,UHF 在线监测技术能够提高变电站 GIS 局部放电的监测效果,具有很好的应用前景。提高监测灵敏度的关键在于选择合适的传感器安装位置。此外,对于全封闭的 GIS 设备 UHF 法宜结合超声波定位技术一起使用。%In view of the increasing application of UHF to the detection of partial discharge, and in combination with the case of UHF technique for GIS patial discharge detection in Guangdong Power Grid substations, this paper analyzes the advantage of UHF based online monitoring technique, and carries out test research of the application effect of PDM UHF system for patial discharge detection. The test results and practical application show that the UHF online monitoring technique can improve the efficiency of detecting GIS partial discharge, and thus have very good application prospect. The key of the technique to improve the monitoring sensitivity is to select right installation position for transducers. In addition, UHF technique is better used with ultrasonic positioning technique for a full-closed GIS device.

  8. An infrared study of galactic OH/IR stars. I. An optical/near-IR atlas of the Arecibo sample

    CERN Document Server

    Jiménez-Esteban, F M; Engels, D; García-Lario, P

    2004-01-01

    In this paper we present optical and near-infrared finding charts, accurate astrometry (~1") and single-epoch near-infrared photometry for 371 IRAS sources, 96% of those included in the so-called Arecibo sample of OH/IR stars (Eder et al. 1988; Lewis et al. 1990a; Chengalur et al. 1993). The main photometric properties of the stars in the sample are presented and discussed as well as the problems found during the process of identification of the optical/near-infrared counterparts. In addition, we also identify suitable reference stars in each field to be used for differential photometry purposes in the future. We find that 39% of the sources (144 in number) have no optical counterpart, 8 of them being invisible even at near infrared wavelengths. The relative distribution of sources with and without optical counterpart in the IRAS two-colour diagram and their characteristic near infrared colours are interpreted as the consequence of the increasing thickness of their circumstellar shells. Among the objects not ...

  9. The GALEX Arecibo SDSS Survey V: The Relation between the HI Content of Galaxies and Metal Enrichment at their Outskirts

    CERN Document Server

    Moran, Sean M; Kauffmann, Guinevere; Davé, Romeel; Catinella, Barbara; Brinchmann, Jarle; Wang, Jing; Schiminovich, David; Saintonge, Amélie; Gracia-Carpio, Javier; Tacconi, Linda; Giovanelli, Riccardo; Haynes, Martha; Fabello, Silvia; Hummels, Cameron; Lemonias, Jenna; Wu, Ronin

    2011-01-01

    We have obtained long-slit spectra of 174 star-forming galaxies with stellar masses greater than 10^10 M_\\odot from the GALEX Arecibo SDSS (GASS) survey. These galaxies have both HI and H_2 mass measurements. The average metallicity profile is strikingly flat out to R_90, the radius enclosing 90% of the r-band light. Metallicity profiles which decline steadily with radius are found primarily for galaxies in our sample with low stellar mass (Log(M_*)<10.2), concentration, and/or mean stellar mass density. Beyond ~R_90, however, around 10 percent of the galaxies in our sample exhibit a sharp downturn in metallicity. Remarkably, we find that the magnitude of the outer metallicity drop is well correlated with the total HI content of the galaxy (measured as f_HI=M_HI/M_*). We examine the radial profiles of stellar population ages and star formation rate densities, and conclude that the galaxies with largest outer metallicity drops are actively growing their stellar disks, with mass doubling times across the who...

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

    Energy Technology Data Exchange (ETDEWEB)

    Deneva, J. S. [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); Stovall, K.; Martinez, J. G.; Jenet, F. [Center for Advanced Radio Astronomy, Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); McLaughlin, M. A.; Bates, S. D.; Bagchi, M. [Department of Physics, West Virginia University, 111 White Hall, Morgantown, WV 26506 (United States); Freire, P. C. C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2013-09-20

    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. The Arecibo Galaxy Environment Survey: II. A HI view of the Abell cluster 1367 and its outskirts

    CERN Document Server

    Cortese, L; Auld, R R; Davies, J I; Catinella, B; Momjian, E; Rosenberg, J L; Taylor, R; Gavazzi, G; O'Neil, K; Baes, M; Boselli, A; Bothun, G; Koribalski, B; Schneider, S; Van Driel, W

    2007-01-01

    We present 21 cm HI line observations of 5x1 square degrees centered on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey. One hundred sources are detected (79 new HI measurements and 50 new redshifts), more than half belonging to the cluster core and its infalling region. Combining the HI data with SDSS optical imaging we show that our HI selected sample follows scaling relations similar to the ones usually observed in optically selected samples. Interestingly all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity. The most striking difference between HI and optically selected samples resides in their large scale distribution: whereas optical and X-ray observations trace the cluster core very well, in HI there is almost no evidence of the presence of the cluster. Some implications on the determination of the cluster luminosity function and HI distribution for samples selected at different wa...

  12. Goals, Strategies and First Discoveries of AO327, the Arecibo All-Sky 327 MHz Drift Pulsar Survey

    CERN Document Server

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

    2013-01-01

    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 degrees, excluding the region within 5 degrees 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 us 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 three millisecond 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 to 38 degrees. We compare ...

  13. 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...

  14. Design of UHF RFID anti-metal tag antenna for cigarette package%卷烟包装用UHF RFID抗金属标签天线的设计

    Institute of Scientific and Technical Information of China (English)

    赵文婧; 杨蓉; 厉丹; 吴双江

    2016-01-01

    为了对内含铝箔的卷烟包装进行防伪识别,设计了一种无源超高频射频识别(UHF RFID)抗金属标签天线。该天线结构简单,可印刷于烟盒表面,并能与包装的金属拉线结构一体化,增强标签的防伪性能。采用Ansoft HFSS软件建模仿真,分析了主要结构参数的变化对标签天线输入阻抗的影响。优化后的结果表明,该天线具有较高的增益、较远的读取距离、良好的方向性和阻抗匹配特性,且带宽能够覆盖915 MHz UHF RFID频段范围。制作标签样品并进行实际测试,结果表明:实测与仿真结果较吻合,读取距离可达8 m,能够满足实际应用的需求。%A passive UHF RFID anti⁃metal tag antenna was designed for anti⁃counterfeit identification of the cigarette pa⁃ckage containing aluminum foil. The antenna has simple structure,and can be printed on the surface of the cigarette package and integrated with the package′s metal wire structure to enhance the anti⁃counterfeiting performance of the tag. The Ansoft HFSS software is used for modeling and simulation. The influences of the main structure parameters on input impedance of the tag antenna are analyzed. The optimal results show that the antenna has high gain,far read range,good directivity and impedance matching characteristics,and the bandwidth of the tag antenna can cover the UHF RFID frequency band range of 915 MHz. A tag sample was produced and tested practically. The results show that the actual measurement result is match to the simulation result,the read range can reach up to 8 m,and the antenna can meet the requirement of the practical application.

  15. 一种用于无源UHF RFID应答器的阻抗匹配方法%A Novel Impedance Matching Approach for Passive UHF RFID Transponder ICs

    Institute of Scientific and Technical Information of China (English)

    陈力颖; 毛陆虹; 吴顺华; 郑轩

    2008-01-01

    This paper presents a novel impedance matching approach for passive UHF RFID transponder ICs, which are compatible with the ISO/IEC 18000-6B standard and operate in the 915MHz ISM band. The passive UHF RFID transpon- der with complex impedances is powered by received RF energy. The approach uses the parasitic inductance of the antenna to implement ASK modulation by adjusting the capacitive reactance of the matching network, which changes with the backscatter circuit. The impedance matching achieves maximum power transfer between the reader, antenna, and tran- sponder. The transponder IC, whose operating distance is more than 4m with the impedance matching approach, is fabrica- ted using a Chartered 0. 35μm two-poly four-metal CMOS process that supports Schottkv diodes and EEPROM.%提出了一种可以在915MHz ISM频带下工作的、符合ISO/IEC 18000-6B标准的无源UHF RFID应答器的阻抗匹配方法.该UHF RFID应答器具有复数阻抗并从射频电磁场接收能量.该阻抗匹配方法利用天线的寄生电感,通过调整反向散射电路的电容来改变匹配网络的容抗,从而实现ASK调制.而且,该阻抗匹配方法在阅读器、天线与应答器之间达到了最大的功率传输.采用该阻抗匹配方法的应答器芯片通过支持肖特基二极管和EEPROM的Chartered 0.35μm 2P4M CMOS工艺进行流片,经测试其工作距离约为4m.

  16. 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.

    Scenarios and business models for mobile network operators utilizing the hybrid use concept of the UHF broadcasting spectrum

    Directory of Open Access Journals (Sweden)

    S. Yrjölä

    2016-09-01

    Full Text Available This paper explores and presents scenarios and business models for mobile network operators (MNOs in the novel hybrid use spectrum sharing concept of the Ultra High Frequency broadcasting spectrum (470-790 MHz used for Digital Terrestrial TV (DTT and Mobile Broadband (MBB. More flexible use of the band could lead to higher efficiency in delivering fast growing and converging MBB, media and TV content to meet changing consumer needs. On one hand, this could be beneficial for broadcasters (BC, e.g., by preserving the spectrum, by providing additional revenues, or by lowering cost of the spectrum and, on the other hand, for MNOs to gain faster access to new potentially lower cost, licensed, below 1GHz spectrum to cope with booming data traffic. As a collaborative benefit, the concept opens up new business opportunities for delivering TV and media content using MBB network with means to introduce this flexibly. This paper highlights the importance of developing sound business models for the new spectrum use concept, as they need to provide clear benefits to the key stakeholders to be adopted in real life. The paper applies a future and action oriented approach to the MBB using the concept to derive scenarios and business models for MNOs for accessing hybrid UHF bands. In order to address the convergence and transformation coming with the concept, business models are first developed for the current situation with separate exclusive spectrum bands. Novel business scenarios are then developed for the introduction of the new flexible hybrid UHF spectrum concept. The created business model indicates that the MNOs could benefit significantly from the new UHF bands, which would enable them to cope with increasing data traffic asymmetry, and to offer differentiation through personalized broadcasting and new media services. Moreover, it could significantly re-shape the business ecosystem around both the broadcasting and the mobile broadband by introducing

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

    Science.gov (United States)

    Parr, Andreas; Miesen, Robert; Vossiek, Martin

    2016-06-25

    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.

  18. 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.

  19. Financial Market Risk Measurement Using UHF Data under Multiple Dimensions Information ——Based on UHF ACD Model and UHF-GARCH Model%多重信息维度下金融市场风险的高频计量——基于超高频数据ACD模型和UHF-GARCH模型、

    Institute of Scientific and Technical Information of China (English)

    苗晓宇

    2012-01-01

    UHF data are real-time trading records and the most accurate performance of all information in the stock market. Using high-frequency data to measure the financial risks can undoubtedly improve the accuracy of risk measurement. This pa- per, based on the results of existing research, brings the behavioral charactefistcs of traders, trading volume, bid-ask spread, transaction speed and other information dimension into the risk measurement model, and compares the accuracy of measurement with the model without considering such information dimensions. The results confirm that the model considered multiple dimensions of information can be more accurate for measuring financial market risk.%超高频数据是交易的实时记录,是所有信息在股市上的最精确的表现。考虑使用高频数据来测度金融风险无疑能够提高风险测度的准确性。本文在现有研究成果的基础上,将交易者行为特征、交易量、买卖价差、交易速度等信息维度纳入金融高频风险的计量中,并与没有考虑这些信息维度时测度的准确性进行对比,结果表明,考虑多重信息维度的模型能够更准确地测度金融市场风险。

  1. 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.

  2. A UHF RFID positioning system for use in warehouse navigation by employees with cognitive disability.

    Science.gov (United States)

    Gunther, Eric J M; Sliker, Levin J; Bodine, Cathy

    2017-11-01

    Unemployment among the almost 5 million working-age adults with cognitive disabilities in the USA is a costly problem in both tax dollars and quality of life. Job coaching is an effective tool to overcome this, but the cost of job coaching services sums with every new employee or change of employment roles. There is a need for a cost-effective, automated alternative to job coaching that incurs a one-time cost and can be reused for multiple employees or roles. An effective automated job coach must be aware of its location and the location of destinations within the job site. This project presents a design and prototype of a cart-mounted indoor positioning and navigation system with necessary original software using Ultra High Frequency Radio Frequency Identification (UHF RFID). The system presented in this project for use within a warehouse setting is one component of an automated job coach to assist in the job of order filler. The system demonstrated accuracy to within 0.3 m under the correct conditions with strong potential to serve as the basis for an effective indoor navigation system to assist warehouse workers with disabilities. Implications for rehabilitation An automated job coach could improve employability of and job retention for people with cognitive disabilities. An indoor navigation system using ultra high frequency radio frequency identification was proposed with an average positioning accuracy of 0.3 m. The proposed system, in combination with a non-linear context-aware prompting system, could be used as an automated job coach for warehouse order fillers with cognitive disabilities.

  3. UHF-RFID solutions for logistics units management in the food supply chain

    Directory of Open Access Journals (Sweden)

    Paolo Barge

    2013-09-01

    Full Text Available The availability of systems for automatic and simultaneous identification of several items belonging to a logistics unit during production, warehousing and delivering can improve supply chain management and speed traceability controls. Radio frequency identification (RFID is a powerful technique that potentially permits to reach this goal, but some aspects as, for instance, food product composition (e.g. moisture content, salt or sugar content and some peculiarities of the production environment (high moisture, high/low temperatures, metallic structures have prevented, so far, its application in food sector. In the food industry, composition and shape of items are much less regular than in other commodities sectors. In addition, a wide variety of packaging, composed by different materials, is employed. As material, size and shape of items to which the tag should be attached strongly influence the minimum power requested for tag functioning, performance improvements can be achieved only selecting suitable RF identifier for the specific combination of food product and packaging. When dealing with logistics units, the dynamic reading of a vast number of tags originates simultaneous broadcasting of signals (tag-to-tag collisions that could affect reading rates and the overall reliability of the identification procedure. This paper reports the results of an extensive analysis of the reading performance of UHF RFID systems for multiple dynamic electronic identification of food packed products in controlled conditions. Products were considered singularly or arranged on a logistics pallet. The effects on reading rate and reading zone of different factors, among which the type of product, the number and position of antennas, the field polarization, the reader RF power output, the interrogation protocol configuration as well as the transit speed, the number of tags and their interactions were analysed and compared.

  4. 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.

  5. PMSE observations with the EISCAT VHF- and UHF-radars: Ice particles and their effect on ambient electron densities

    Science.gov (United States)

    Li, Qiang; Rapp, Markus

    2013-11-01

    It is now well understood that the occurrence of PMSE is closely connected to the presence of ice particles. These ice particles modify the ambient electron density by electron attachment which occasionally leads to large electron density depletions which have also been called ‘biteouts’. There has been some debate in the literature regarding the relative depth of such depletions which is usually expressed by the parameter Λ=|ZA|NA/ne. Here, |ZA|NA is the charge number density of ice particles and ne is the electron density. In this paper, we present, for the first time, the statistical distribution of Λ using measurements with the EISCAT VHF- and UHF-radars. Based on 25 h of simultaneous observations, we derived a total of 757 Λ values based on 15 min of data each. In each of these cases, PMSE were observed with the EISCAT VHF-radar but not with the UHF-radar and the UHF-measurement were hence used to determine the electron density profile. From these 757 cases, there are 699 cases with Λ⪡1, and only 33 cases with Λ>0.5 (21 cases with Λ>1). A correlation analysis of Λ versus PMSE volume reflectivities further reveals that there is no strong dependence between the two parameters. This is in accordance with current PMSE-theory based on turbulence in combination with a large Schmidt-number. The maxima of Λ from each profile show a negative relationship with the undisturbed electron densities deduced at the same altitudes. This reveals that the variability of Λ mainly depends on the variability of the electron densities. In addition, variations of aerosol number densities may also play a role. Although part of the observations were conducted during the HF heating experiments, the so-called overshoot effects did not significantly bias our statistical results. In order to avoid missing biteouts because of a superposition of coherent and incoherent scatter in the UHF-data, we finally calculated spectral parameters n by applying a simple fit to auto

  6. Effect of process parameters on porosity formation ratio in dual-beam laser welding of aluminum alloys with filler wire%双光束激光填丝焊工艺对铝合金焊接气孔率的影响

    Institute of Scientific and Technical Information of China (English)

    雷正龙; 李颖; 陈彦宾; 孙忠绍; 张益坤

    2013-01-01

    以LF6铝合金为材料,CO2激光为热源,开展了双光束激光填丝焊气孔特性分析.与单光束激光填丝焊及双光束自熔焊相比,双光束激光填丝焊能够抑制气孔的产生,尤其是并行双光束激光焊抑制气孔效果更明显.在此基础上进一步分析了保护气体成分和激光能量对焊接气孔率的影响.结果表明,采用氦气保护时,等离子体对激光的屏蔽作用小,能够稳定焊接过程;激光功率过大或者过小都会导致匙孔的不稳定,造成焊缝气孔率增加.%The characterizations of porosity in dual-beam laser welding with filler wire of LF6 aluminum alloys were studied. Compared with the single beam laser welding with filler wire and the dual-beam laser self-fusible welding, the dual-beam laser welding with filler wire can restrain the porosity formation. Especially , the dual-beam laser welding with parallel arrangement has a better effect on inhibition of porosity. Furthermore, the effects of shielding gas component and laser energy on porosity formation ratio were analyzed. The results show that, when the helium is used as the shielding gas, the area of plasma decreases as well as the shielding effect of the plasma on laser deceases, and the welding process become more stable. At the same time, the laser power must be proper, and both too high and too low laser power make the porosity formation ratio enlarged.

  7. Detected Galaxies and Large Scale Structure in the Arecibo L-band Feed Array Zone of Avoidance Survey (ALFAZOA)

    Science.gov (United States)

    Henning, Patricia A.; Sanchez-Barrantes, Monica; McIntyre, Travis; Minchin, Robert F.; Momjian, Emmanuel; Butcher, Zhon; Rosenberg, Jessica L.; Schneider, Stephen E.; Staveley-Smith, Lister; van Driel, Wim; Ramatsoku, Mpati; Koribalski, Baerbel; Spears, Brady

    2017-01-01

    While large, systematic redshift surveys of galaxies have been conducted for decades, lack of information behind the Milky Way (the Zone of Avoidance) contributes uncertainty to our picture of dynamics in the local universe. Controversy persists for the dipole calculated from galaxy and redshift surveys compared to the CMB. Depth in redshift space is an issue, as is incomplete sky mapping, even of supposed all sky redshifts surveys. For instance, the wide-angle 2MASS Redshift Survey retains a gap of 5-8 deg around the Galactic plane. Fortunately, there is no ZOA at 21cm, except for velocities occupied by the Galaxy. This long-wavelength spectral line passes unimpeded through dust, and is unaffected by stellar confusion. With immediate redshift determination, a 21-cm survey produces a 3-dimensional map of the distribution of obscured galaxies which contain HI. It traces large-scale structure right across the Galactic Plane, and identifies obscured mass overdensities relevant to flow-field studies.ALFAZOA is a blind HI survey for galaxies behind the Milky Way covering more than 1000 square degrees of the Arecibo sky. It proceeds in two phases: shallow (completed) and deep (ongoing). The shallow survey (rms ~5-7 mJy) mapped the region within Galactic longitude l = 30 - 75 deg, and latitude b = -10 to +10 deg, detecting several hundred galaxies to about 12,000 km/s, tracing large-scale structure across the plane. The deep survey (rms ~1 mJy), in both the inner (Galactic longitude 30 - 75 deg and latitude plus/minus 2 deg) and outer (longitude 175 - 207 deg and latitude = +1 to -2 deg) Galaxy is ongoing, with detections reaching to 18,000 km/s. Analysis of detections to date, and large-scale structure mapped, will be presented.

  8. [Exposure to VHF and UHF electromagnetic fields among workers employed in radio and TV broadcast centers. I. Assessment of exposure].

    Science.gov (United States)

    Zmyślony, M; Aniołczyk, H; Bortkiewicz, A

    2001-01-01

    Nowadays, radio and television have become one of the areas of the human technical activity that develops most rapidly. Also ultra-short waves of VHF (30-300 MHz) and UHF (0.3-3 GHz) bands have proved to be the most important carriers of radio and TV-programs. In Poland, a network of radio and TV broadcast centers (RTCN) with high (over 200 m) masts was set up in the 1960s and 1970s. These centers concentrate the majority of stations broadcasting national and local programs (for areas within the RTCN range). At present, the RTCN established several decades ago are equally important. The assessment of the exposure to electromagnetic fields among workers of multi-program broadcast stations is complicated and feasible only to a certain degree of approximation because of changing conditions of exposure in individual stations during their long history, resulting from the changing numbers and types of transmitters installed. In this work, the method of retrospective estimation of exposure dose is described, and the results of the assessment carried out at three kinds of typical RTCN are discussed. The results of the analysis indicate that the workers of RTCN are exposed primarily to electromagnetic fields of VHF and UHF bands, but this exposure may be considered as admissible, hence it should not exert an adverse effect on the workers' health.

  9. On the Feasibility of Unlicensed Communications in the TV White Space: Field Measurements in the UHF Band

    Directory of Open Access Journals (Sweden)

    M. Fadda

    2015-01-01

    Full Text Available In practical unlicensed communications in TV band, radio devices have to identify, at first, the transmission opportunities, that is, the portion of the spectrum licensed for broadcasting services unoccupied in a certain region at certain time, that is, the so-called TV white space. In this paper the outcome of field measurements in the UHF TV band (470–860 MHz conducted in EU is presented. To obtain empirical values for the parameters upon which unlicensed radio devices are able to distinguish in a real scenario between empty and occupied TV channels, signal power measurements have been performed in Italy, Spain, and Romania on rural, suburban, and urban sites, at different heights over the ground by using different analysis bandwidths. The aim of this work is to provide a set of practical parameters upon which harmless unlicensed communication in the UHF TV white space is feasible. The results have been analyzed with respect to the hidden node margin problem, spectrum sensing bandwidth, and occupancy threshold.

  10. UHF electromagnetic structures inkjet printed on temperature sensitive substrates: A comparative study of conductive inks and sintering methods to enable low cost manufacture

    NARCIS (Netherlands)

    Sanchez-Romaauera, V.; Wünscher, S.; Abbel, R.J.; Zial, M.A.; Oyeka, D.; Turki, B.M.M.; Batchelor, J.C.; Parker, E.A.; Schubert, U.S.; Yeates, S.G.

    2013-01-01

    In this paper we demonstrate the use of inkjet printing as a facile digital fabrication tool for the cost effective manufacture of UHF RFID transfer tattoo tags and Frequency Selective Surfaces on low-cost flexible and porous substrates. Electrical and morphological properties of conductive features

  11. UHF electromagnetic structures inkjet printed on temperature sensitive substrates: A comparative study of conductive inks and sintering methods to enable low cost manufacture

    NARCIS (Netherlands)

    Sanchez-Romaauera, V.; Wünscher, S.; Abbel, R.J.; Zial, M.A.; Oyeka, D.; Turki, B.M.M.; Batchelor, J.C.; Parker, E.A.; Schubert, U.S.; Yeates, S.G.

    2013-01-01

    In this paper we demonstrate the use of inkjet printing as a facile digital fabrication tool for the cost effective manufacture of UHF RFID transfer tattoo tags and Frequency Selective Surfaces on low-cost flexible and porous substrates. Electrical and morphological properties of conductive features

  12. The Shape of Near-Earth Asteroid 275677 (2000 RS11) From Inversion of Arecibo and Goldstone Radar Images

    Science.gov (United States)

    Brauer, Kaley; Busch, Michael W.; Benner, Lance A. M.; Brozovic, Marina; Howell, Ellen S.; Nolan, Michael C.; Springmann, Alessondra; Giorgini, Jon D.; Taylor, Patrick A.; Jao, Joseph S.

    2015-11-01

    We observed near-Earth asteroid 2000 RS11 with the Arecibo and Goldstone planetary radars during a 0.035 au approach in March 2014, obtaining delay-Doppler images between March 13 and March 17. The finest-resolution images have range resolution of 7.5 m/pixel and show that RS11 is a contact binary with complex topography. We used the SHAPE software package (Magri et al., Icarus 186, 156-160 2007) to create a physical model of RS11 and its spin state from these delay-Doppler images.The rotation period of RS11 is well constrained from optical lightcurves, P = 4.444 ± 0.001 h (Warner et al., Minor Planet Bulletin 41, 160; 2014 and Benishek, Minor Planet Bulletin 41, 257; 2014). We found two possible pole directions and corresponding shape models, mirror images of one another, which provide equally good fits to the radar data. RS11’s pole direction is either (λ , β) = (155°, 30°) ± 10° or (335°, -30°) ± 10° in J2000 ecliptic coordinates. The most likely pole directions of RS11 are not aligned with the heliocentric orbit normal and instead have an obliquity within 10° of 56° or 124°.Our best-fit shape models are 1400-vertex polyhedra comprising two lobes in contact. The lengths of RS11’s principal axes are 698 ± 71 m, 578 ± 59 m, and 758 ± 77 m. RS11 has a volume of 0.086 ± 0.026 km^3. The long axis of RS11’s larger lobe is 751 ± 77 m and the long axis of the smaller lobe is 398 ± 41 m; the volume ratio between these lobes is roughly 2.7 ± 10%. Spectral data informs us that RS11 is an S-class object (Lazzarin et al., Icarus 169, 379; 2004).RS11's shape is unusual compared with those of other contact binary NEAs imaged by radar. Its larger lobe is flattened. Additionally, while the neck between the smaller and larger lobes of most contact binaries is located near the larger lobe's longest principal axis (such as in the cases of 25143 Itokawa and 4179 Toutatis), RS11's neck is near its larger lobe's shortest principal axis. RS11 is the first

  13. A Low-Power PIE decoder and BLF genarator for UHF RFID tag%一种用于UHF RFID标签的低功耗PIE解码与BLF生成电路

    Institute of Scientific and Technical Information of China (English)

    唐龙飞; 庄奕琪; 孔泽斌; 刘伟峰; 靳钊

    2011-01-01

    提出了一种全新的低功耗PIE(Pulse Interval Encoded)解码及反向散射链路频率BLF(Backscatter Link Frequency)生成电路,用于符合EPC Gen2协议的无源超高频射频识别(UHF RFID)芯片.该电路在读写器发送命令时,产生控制信号.所产生信号控制两个积分器生成三个比较电压,并通过两个比较器进行比较,完成对PIE信号的解码;同时控制另一积分器,产生参考电压,控制弛张振荡器生成符合协议要求的BLF.基于TSMC 0.18μm CMOS工艺的仿真结果表明,本文所提出电路在1V工作电压下功耗为1.36μW,采用该结构的芯片可以提高工作距离以及读取速率.%In this paper, a novel low power PIE(Pulse Interval Encoded) decoder and backscatter link frequency (BLF) generator for UHF RFID transponders which meet the EPC Gen2 UHF RFID protocol are presented. Control signals are generated when the reader sends commands. Two integrators controlled by the control signals generate three voltages. By comparing these 3 voltages with two comparators, the circuits decode the PIE signal. Another integrator controlled by the control signals generates a reference voltage which makes a relaxation oscillator output a BLF that meets the Gen2 protocol. The simulation results under TSMC 0.18um CMOS technology show that the total power of the proposed circuits is 1.36μW at IV operating voltage. As a result, the tag with the proposed circuits can acquire longer read range and higher read rates.

  14. Optimization of multi-tag identification for UHF RFID multi-antenna tag readers%多天线UHF RFID标签阅读器的多标签识别优化算法

    Institute of Scientific and Technical Information of China (English)

    仲元昌; 刘春伟; 丁漩; 王旭

    2012-01-01

    This paper pays attention to the problem that it is difficult for existing UHF RFID ( radio frequency identification) tag readers with a single antenna to assure their reliability in multi-tag identification, and proposes a RFID multi-antenna identification mode, which increases the number of antennas to increase the recovery and reduce the blind zone during identification, and finally to improve the reliability of multi-tag identification. This paper adopts the genetic algorithm ( GA) to optimize the number of antennas during identification by using the operators of selection, crossover, and mutation for improving the reliability of multi-tag identification of a RFID.reader. The experimental results show that the proposed RFID multi-antenna identification mode is effective in improving the recovery and reducing blind zone, and the identification optimizing algorithm based GA has the satisfied capability in searching and convergence, it can improve the reliability of system identification. This study provides a new idea for the application of the UHF RFID technology in complex environments.%针对现有的超高频(UHF)射频识别(RFID)标签阅读器使用单个天线,难以保证多标签识别可靠性的问题,提出了一种通过增加天线个数,以增强覆盖效果、减少识别盲区、增强多标签识别可靠性的RFID多天线识别模式,并利用遗传算法对识别过程中启用天线的个数进行优化,通过合理处理选择、交叉、变异遗传算子以提高RFID阅读器多标签识别的可靠性.实验结果表明:增加天线个数可以增强覆盖效果、减少识别盲区;基于遗传算法的识别优化算法具有良好的搜索性和收敛性,提高了系统识别的可靠性.该研究为复杂环境下应用超高频RFID技术提供了新思路.

  15. 分布式天线UHF RFID系统读取率的评估方法%Evaluation Method of Read Rate from Distributed Antennas for UHF RFID Systems

    Institute of Scientific and Technical Information of China (English)

    仲元昌; 郭开林; 陈辉

    2011-01-01

    A distributed antenna structure operating at the ultra-high frequency( UHF) is presented in order to evaluate read rate of radio frequency identification (RFID) systems. The distributed four antennas are connected to a reader with radio frequency switch. The antennas are deployed on opposite sides in both vertical and horizontal directions of read area due to the polarisation of the electromagnetic field. This distributed structure can heighten the coverage effect of system and decrease read blind spots. This evaluative parameter is called as reliable I-dentification rate. The evaluative paramater can estimate read rate of RFID system according to actual identification situation of four distributed antennas. Simulation experimental results indicate that this evaluation method of read rate is effective based on four distributed antennas for UHF RFID systems.%为了对超高频射频识别系统的读取率进行评估,提出了基于分布式天线结构的评估方法。分布式天线结构是指通过射频开关选择器件将四个天线连接到一个阅读控制器上,考虑到电磁场极化现象,增强覆盖效果,减少阅读盲区,天线分布在识别区域的水平和垂直两个相对的方向上。为了实现对系统读取率的评估,根据四个天线实际的识别情况,定义了系统读取率的评估参数,即可靠识别率。仿真实验结果表明:基于分布式天线结构的这种评估方法可以有效的对UHF RFID系统的读取率进行评估。

  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. 单光源双光路激光并行共焦测量系统设计%Design of laser parallel confocal measurement system with single source and dual beam paths

    Institute of Scientific and Technical Information of China (English)

    余卿; 余晓芬; 崔长彩

    2013-01-01

    To avoid the Talbot effect that is a multiple imaging in the traditional laser parallel confocal measurement, this paper introduces a Digital Micromirror Device(DMD) into the laser parallel confocal measurement to recognize the in-focus image. By taking the DMD as an optical splitting system, it is verified to be a flexible array source, and can not bring Talbot effect into the measurement system. However, the DMD is not an effectual splitting source as it can not converge the split ray effectively. Based on the characteristics of DMD, a laser parallel confocal measurement system with a single source and dual beam paths is constructed by combining a DMD and a Microlens Array(MLA). In this system, the position of in-focus image can be distinguished with the beam path of DMD and the high precision measurement can be completed with the beam path of MLA. The theoretical analysis and the experiment results indicate that the difference between the positions of in-focus images under two kinds of optical detection paths is about 2 μm. Moreover, the influence of Talbot effect on the laser parallel confocal measurement becomes weaker, and the parallel confocal measurement with high precision is achieved.%针对传统激光并行共焦测量过程中存在的泰伯效应,提出将数字微镜器件(DMD)引入激光并行共焦测量系统来正确辨识正焦面的位置.采用了DMD作为光分束器件,从理论上验证了它是一种投影式的阵列光源,对激光分束后不会在光路方向上产生泰伯像;同时,考虑DMD不能对分束后的光线产生会聚作用,并非高效的并行光源分束器件,本文将DMD与微透镜阵列(MLA)结合构建了单光源双光路并行共焦测量系统.该系统利用DMD光路探测正焦面位置,利用微透镜阵列光路进行精确的共焦测量.实验结果表明,两种光路下的正焦面位置仅相差2 μm,在一个泰伯间距范围之内,可以较好地克服泰伯效应对激光并行共焦测量的

  18. Design and analysis of novel UHF RFID anti-metal tag antenna%一种新型 UHF RFID 抗金属标签天线的设计与分析

    Institute of Scientific and Technical Information of China (English)

    许长青; 王朱丹; 盛喆; 杨樊

    2013-01-01

      提出了一种用于金属物体的超高频射频识别标签天线,该天线适用于多标准超高频射频识别系统。采用在偶极子结构上增加环形微带线来增大输入阻抗,极大地提高了标签天线的增益特性。利用电磁仿真软件分析了天线性能,仿真与测试结果吻合良好。整个天线的面积为100 mm×40 mm,由于采用表面印刷结构,使得标签成本低廉、易于批量生产。%An ultra high frequency(UHF)radio frequency identification(RFID)tag antenna for metallic objects is presented. The antenna is applied to multi⁃standard UHF RFID system. The antenna is fabricated on a thin flexible PET substrate with the thickness of 1 mm. A loop microstrip line is added in the dipole antenna structure to enhance input impedance,which improved the gain characteristic of the antenna immensely. Based on simulated model,The antenna performance is analyzed with electro⁃magnetic simulation software. The measured results are in good agreement with simulated results. The area of the whole antenna is 100 mm×40 mm. The tag obtains the advantage of low cost and can be mass⁃producd due to its printed structure.

  19. 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 to...

  20. Consolidated Ground Segment Requirements for a UHF Radar for the ESSAS

    Science.gov (United States)

    Muller, Florent; Vera, Juan

    2009-03-01

    ESA has launched a nine months long study to define the requirements associated to the ground segment of a UHF (300-3000 MHz) radar system. The study has been awarded in open competition to a consortium led by Onera, associated to the Spanish companies Indra and its sub-contractor Deimos. After a phase of consolidation of the requirements, different monostatic and bistatic concepts of radars will be proposed and evaluated. Two concepts will be selected for further design studies. ESA will then select the best one, for detailed design as well as cost and performance evaluation. The aim of this paper is to present the results of the first phase of the study concerning the consolidation of the radar system requirements. The main mission for the system is to be able to build and maintain a catalogue of the objects in low Earth orbit (apogee lower than 2000km) in an autonomous way, for different sizes of objects, depending on the future successive development phases of the project. The final step must give the capability of detecting and tracking 10cm objects, with a possible upgrade to 5 cm objects. A demonstration phase must be defined for 1 m objects. These different steps will be considered during all the phases of the study. Taking this mission and the different steps of the study as a starting point, the first phase will define a set of requirements for the radar system. It was finished at the end of January 2009. First part will describe the constraints derived from the targets and their environment. Orbiting objects have a given distribution in space, and their observability and detectability are based on it. It is also related to the location of the radar system But they are also dependant on the natural propagation phenomenon, especially ionospheric issues, and the characteristics of the objects. Second part will focus on the mission itself. To carry out the mission, objects must be detected and tracked regularly to refresh the associated orbital parameters

  1. 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

  2. Performance evaluation of UHF RFID technologies for real-time bus recognition in the Taipei Bus Station.

    Science.gov (United States)

    Own, Chung-Ming; Lee, Da-Sheng; Wang, Ti-Ho; Wang, De-Jun; Ting, Yu-Lun

    2013-06-18

    Transport stations such as airports, ports, and railways have adopted blocked-type pathway management to process and control travel systems in a one-directional manner. However, this excludes highway transportation where large buses have great variability and mobility; thus, an instant influx of numerous buses increases risks and complicates station management. Focusing on Taipei Bus Station, this study employed RFID technology to develop a system platform integrated with modern information technology that has numerous characteristics. This modern information technology comprised the following systems: ultra-high frequency (UHF) radio-frequency identification (RFID), ultrasound and license number identification, and backstage graphic controls. In conclusion, the system enabled management, bus companies, and passengers to experience the national bus station's new generation technology, which provides diverse information and synchronization functions. Furthermore, this technology reached a new milestone in the energy-saving and efficiency-increasing performance of Taiwan's buses.

  3. Wearable Passive E-Textile UHF RFID Tag Based on a Slotted Patch Antenna with Sewn Ground and Microchip Interconnections

    Directory of Open Access Journals (Sweden)

    Johanna Virkki

    2017-01-01

    Full Text Available We present a wearable passive UHF RFID tag based on a slotted patch antenna comprising only textile materials (e-textile, textile substrate, and conductive yearn. As a novel manufacturing approach, we realize the patch-to-ground and antenna-to-IC interfaces using only conductive thread and a sewing machine. We outline the electromagnetic optimization of the antenna for body-worn operation through simulations and present a performance comparison between the e-textile tag and a tag produced using regular electronics materials and methods. The measured results show that the textile tag achieves the electrical performance required in practical applications and that the slotted patch type antenna provides stable electromagnetic performance in different body-worn configurations.

  4. Low power RF/analog f ront-end solution for UHF RFID%低功耗UHF RFID射频/模拟前端解决方案

    Institute of Scientific and Technical Information of China (English)

    杜永乾; 庄奕琪; 李小明; 刘伟峰

    2014-01-01

    A RF/analog front-end for passive UHF RFID was presented .The system power consump-tion was optimized by time-divided and domain-divide power supply .The overall circuits included volt-age multiplier ,three voltage regulators ,power-on-reset ,ring oscillator ,voltage reference ,modulator and demodulator ,where the power efficiency voltage multiplier was improved through threshold volt-age compensation ,and the power efficiency was not smaller than 48% ;the low power current-sum-ming voltage reference had both high accuracy and small chip size ;the amplitude shift keying (ASK) demodulator without huge passive devices solved the error-detection and distortion problem through system level .The RF/analog front-end was designed and implemented in SMIC 0 .18 μm CMOS tech-nology .Test results show that the total direct current (DC) power consumption is 3 .6μA .The active area of the RF/analog front-end is about 0 .27 mm2 .The RF/analog front-end was finally integrated into a full UHF RFID chip ,and tested by a commercial reader .The reading distance is larger than 6 m ,and the read speed of the RFID chip reaches 89 .9/s .%提出了用于无源超高频射频识别(UHF RFID)芯片的射频/模拟前端.该射频/模拟前端通过系统分区和分时供电优化了系统功耗,子电路包括整流电路、基准电路、三轨稳压电路、解调/调制电路、上电复位电路以及时钟电路.通过引入阈值补偿,将全CMOS整流电路的整流效率提升至不低于48%;电流求和型亚阈值基准电路在保证基准精度的同时,有效降低了功耗和芯片面积;无需大尺寸无源器件的解调电路,并从系统架构层面解决了解调失真的问题.该射频/模拟前端电路采用SMIC0.18μmCMOS工艺库仿真并投片验证,测试结果表明:直流功耗为3.6μA,芯片有效面积为0.27mm2.将该射频/模拟前端电路集成至一款UHFRFID标签芯片中,采用商用阅读器进

  5. Detection of Typical GIS Partial Discharge Based on UHF Method%基于超高频法的典型GIS局部放电检测

    Institute of Scientific and Technical Information of China (English)

    孙曙光; 陆俭国; 俞慧忠; 沈建位; 金少华

    2012-01-01

    GIS partial discharge detection is a scientific and effective way for insulation condition monitoring. A GIS model and the detection system based on UHF method has been set up. Several typical GIS partial discharge is studied and using power phase analysis a detailed analysis of characteristics under different voltage is made; Combined with conventional partial discharge detection method, the partial discharge quantity estimation of UHF signal is also made. All of these lay a foundation for the study of partial discharge intelligent recognition and the relationship between UHF signal and partial discharge quantity to improve the engineering utility of UHF partial discharge detection.%GIS局部放电检测是GIS绝缘状态监测的一种科学有效的方法.笔者构建了GIS实验模型以及基于超高频法的局部放电在线检测系统,对GIS中典型的几种局部放电特征进行了研究,采用基于相位的分析模式详细分析了不同放电类型在不同电压条件下的放电特征,并结合常规局部放电测试仪,对UHF信号的放电量进行估计,为进一步进行放电类型的智能模式识别及研究超高频信号与放电量关系提供了试验依据,以提高UHF局部放电检测的工程实用性.

  6. Design and Verification of Passive UHF RFID Tag with Integrated Temperature Sensor%集成温度传感器的无源UHF RFID标签设计与验证

    Institute of Scientific and Technical Information of China (English)

    战金雷; 谢生; 管坤; 毛陆虹; 张世林

    2013-01-01

    A passive RFID tag with an integrated ultra-low-power temperature sensor is designed for the EPC C1 Gen-2 protocol in the UHF frequency band. The sensor tag consists of an analog/RF front-end, a logic control circuit,a temperature sensor circuit,and EEPROM memory in standard CMOS process. Based on the method of digi-talizing and sampling in time-domain, the on-chip temperature sensor is implemented by multiplexing the bias current and clock signal of the analog front-end, and the pulse length associated with temperature is sampled in time-domain and digitalized for thermal sensing. The pre-layout simulation results based on SMIC 0. 18 μm 2P4M CMOS process indicate that the average power dissipation of temperature sensor is only 100 nW,and the sensor tag has a resolution of 0 . 4℃ in the range from-20℃ to 80℃. All the results of either post-simulation or FPGA verifi-cation exhibit that the passive UHF RFID tag has excellent temperature sensor function.%针对超高频EPC C1 Gen-2协议,设计了一款集成温度传感器的无源RFID标签。系统整体构架包括射频模拟前端、数字逻辑控制电路、温度传感电路和EEPROM存储器4部分。通过复用模拟前端电路产生的电流作为温度转换模块的偏置电流,采用时域数字量化法设计出极低功耗的温度传感电路。基于SMIC 0.18μm 2P4M CMOS工艺库的仿真结果表明,所设计温度传感器的功耗仅为100 nW。集成温度传感器的RFID标签电路仿真及FPGA验证结果表明,所设计传感标签芯片的测温范围在-20益~80益,有效分辨率为0.4益。

  7. 集成于无源UHF RFID标签的新结构CMOS温度传感器%A New CMOS Temperature Sensor Iintegrated in the Passive UHF RFID Tag

    Institute of Scientific and Technical Information of China (English)

    张欢; 毛陆虹; 王倩; 谢生; 张世林

    2011-01-01

    A new temperature sensor integrated in the passive UHF RFID tag is designed. Two currents with the opposite temperature coefficient are generated by making use of a cascode current mirror with high PSRR, to realize the supply voltage and temperature compensation. The pulse signal related to the temperature is generated by a similar differential architecture, it effectively overcomes the errors caused by process variation. The counting clock signal is provided by the local oscillator of the tag. And the oscillator frequency controlled by the bias current is approximately independent of the supply voltage and temperature. It is implemented in SMIC 0. 18μm 2P4M CMOS process,as shown in the simulation results,when the supply voltage is 1.8V and temperature ranges from -10℃to 100 ℃ ,the bias current is 112nA,the oscillator frequency of the tag is 2MHz,and the temperature sensor achieves an effective resolution of 0.5 ℃/LSB,the working currents are 774nA.%设计了一种集成于无源UHF RFID标签芯片的新结构温度传感器.利用高PSRR共源共栅结构的电流镜偏置电路产生两路温度系数相反的电流,实现了偏置电流对电源电压和温度补偿.与温度相关的脉冲信号由类似差分的结构产生,有效的克服了工艺偏差导致的误差.计数时钟信号由标签内部振荡器提供,振荡器频率受偏置电流控制近似与电源电压和温度无关.采用SMIC 0.18μm 2P4M CMOS工艺,仿真结果表明:电源电压为1.8V,温度在-10℃~100℃变化时,偏置电流为112 nA,标签提供的时钟信号频率为2 MHz,温度传感器有效分辨率为0.5℃/LSB,工作电流为774nA.

  8. A Low-Voltage, High Efficiency Power Generation Structure for UHF RFID%一种用于UHF RFID的低压高效电源产生电路

    Institute of Scientific and Technical Information of China (English)

    庞则桂; 庄奕琪; 李小明; 李俊

    2008-01-01

    介绍了一种为无源UHF RFID设计的高效高灵敏度电源产生电路.该电路基于0.18μm工艺,其中包含了两个电荷泵,一个参考电流源和一组偏置电路.由于其偏置电路消除了传统电路中的阈值损失和体效应,使该电路在低压下的电源转换性能得到很大的提高.要为100kΩ负载提供1.5V电源电压,所需最小输入电压为350mV,转换效率为22%.在负载为60kΩ时,最高可以获得29.8%的转换效率.仿真结果表明,新的电路结构比传统的电荷泵具有更优越的性能.%This paper presents a new power generation structure that can provide DC energy tor passive UHF RFID with high sensitivity and high efficiency. The structure is designed with 0.18μm standard CMOS technology, including two charge pumps,a current reference,and a group of bias circuits. Low-voltage performance is improved thanks to the bias structure,which eliminates the threshold voltage drop and body-effect of conventional circuits. A 350mV minimum input level is required to generate a 1.5V power supply for a 100kΩ load with power conversion efficiency (PCE) of 22%. PCE up to 29.8% is achieved with a 60kΩ load. Simulation results show that the new circuit is superior to conventional charge pumps.

  9. 超高频RFID车辆管理控制器设计%Design of UHF RFID Vehicle Management Controller

    Institute of Scientific and Technical Information of China (English)

    张建奇; 张亚军; 陶怡; 张岐

    2016-01-01

    随着汽车保有量的急剧增加,各停车场、小区出入口的车辆管理压力越来越大。为了解决传统车辆管理系统存在的缺陷、缓解停车场、小区出入口的压力,同时为了给用户节约成本,实现精细化管理,本文在现有停车场技术的基础上,设计了一种基于超高频RFID技术的车辆管理控制器。超高频RFID控制器具有多通道识别、比对、存储、控制、显示、语音播报等多种功能,使得车辆管理系统在配有图像对比设备的情况下,更加有效地提高了系统的安全性与可靠性。目前,控制器已稳定可靠运行,标签可靠读取距离可达8米可调,响应时间20ms以内,读取率为99%左右,取得了很好的应用效果,满足车辆管理系统需求。实际应用结果表明:超高频RFID车辆管理控制器可以满足设计要求、工作稳定、可靠,能满足现场使用需求,具有很好的市场前景。%With the dramatic increase in car ownership, the increasing pressure of the each park and the residential entrance are strong. In order to solve the defects of the traditional vehicle management system, to release the pressure of the park and the residential entrance, to reduce costs of users and achieve ifne management, on the basis of existing parking mainstream technology, a vehicle management controller based on UHF RFID technology is designed. The UHF RFID controller has a multi-channel identiifcation, comparison, storage, control, display, voice broadcast and other functions, so that the vehicle management system improves the safety and reliability of the system. At present, the controller is stable and reliable operation, the reliable range of the tags read is up to 8 m adjustable, the response time is about 20ms or less, the tag read rate is about 99%, the controller achieves good application effect and can meet the needs of vehicle management system. Practical application results show that

  10. Improvement of power conversion efficiency in photovoltaic-assisted UHF rectifiers by non-silicide technique applied to photovoltaic cells

    Science.gov (United States)

    Kotani, Koji

    2015-04-01

    Non-silicide PV cell structures were successfully applied to the photovoltaic (PV)-assisted UHF rectifier, which is one example realization of the “synergistic ambient energy harvesting” concept. Silicide blocking of PV cell area was experimentally verified to be effective for increasing photo-generated bias voltage, which resulted in the improved power conversion efficiency (PCE) of the rectifier by enhanced VTH compensation effect. Increase in both transparency of light and quantum efficiency of PV cells obtained by eliminating silicide layer affects the PCE improvement almost equally. 25.8% of PCE was achieved under the conditions of an RF input power of -20 dBm, a frequency of 920 MHz, an output load of 47 kΩ, and a typical indoor light irradiance level of 1 W/m2. In addition, when the non-silicide PV cell technique was applied to the voltage-boosted PV-cell structures, 32.1% peak PCE was achieved at 10 W/m2.

  11. 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).

  12. Development of a Coherent Bistatic Vegetation Model for Signal of Opportunity Applications at VHF UHF-Bands

    Science.gov (United States)

    Kurum, Mehmet; Deshpande, Manohar; Joseph, Alicia T.; O'Neill, Peggy E.; Lang, Roger H.; Eroglu, Orhan

    2017-01-01

    A coherent bistatic vegetation scattering model, based on a Monte Carlo simulation, is being developed to simulate polarimetric bi-static reflectometry at VHF/UHF-bands (240-270 MHz). The model is aimed to assess the value of geostationary satellite signals of opportunity to enable estimation of the Earth's biomass and root-zone soil moisture. An expression for bistatic scattering from a vegetation canopy is derived for the practical case of a ground-based/low altitude platforms with passive receivers overlooking vegetation. Using analytical wave theory in conjunction with distorted Born approximation (DBA), the transmit and receive antennas effects (i.e., polarization, orientation, height, etc.) are explicitly accounted for. Both the coherency nature of the model (joint phase and amplitude information) and the explicit account of system parameters (antenna, altitude, polarization, etc) enable one to perform various beamforming techniques to evaluate realistic deployment configurations. In this paper, several test scenarios will be presented and the results will be evaluated for feasibility for future biomass and root-zone soil moisture application using geostationary communication satellite signals of opportunity at low frequencies.

  13. 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.

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

    Science.gov (United States)

    Xurui, Mao; Beiju, Huang; Hongda, Chen

    2014-12-01

    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.

  15. Long-term UHF RiverSonde river velocity observations at Castle Rock, Washington and Threemile Slough, California

    Science.gov (United States)

    Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.; Ruhl, C.A.

    2005-01-01

    Long-term, non-contact river velocity measurements have been made using a UHF RiverSonde system for several months at each of two locations having quite different flow characteristics. Observations were made on the Cowlitz River at Castle Rock, Washington from October 2003 to June 2004, where the unidirectional flow of the river ranged from about 1.0 to 3.5 m/s. The radar velocity was highly correlated with the stage height which was continually measured by the U. S. Geological Survey. The profile of the along-channel velocity across the water channel also compared favorably with in-situ measurements performed by the Survey. The RiverSonde was moved to Threemile Slough, in central California, in September 2004 and has been operating there for several months. At Threemile Slough, which connects the Sacramento and San Joaquin Rivers, the flow is dominated by tidal effects and reverses direction four times per day, with a maximum speed of about 0.8 m/s in each direction. Water level and water velocity are continually measured by the Survey at the Threemile Slough site, with velocity recorded every 15 minutes from measurements made by an ultrasonic velocity meter (UVM). Over a period of several months, the radar and UVM velocity measurements have been highly correlated, with a coefficient of determination R2 of 0.976. ??2005 IEEE.

  16. Mesospheric observations with the EISCAT UHF radar during polar cap absorption events: 1. Electron densities and negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Collis, P.N. (EISCAT Scientific Association Kiruna (SE)); Rietveld, M.T. (EISCAT Scientific Association, Ramfjordbotn, (NO))

    1990-12-01

    Observations of mesospheric electron density were obtained by the EISCAT UHF radar during several polar cap absorption events (PCA's) in 1989. Both the latitudinal extent and the detailed vertical distribution of the excess ionisation were determined. Continuous observations over more than two days during one event allowed an investigation of the variations in electron density during four twilight intervals. It is shown that at sunrise, at heights above 70 km, electrons are released by ultraviolet photodetachment of a high-affinity negative ion, which may be NO{sub 3}{sup -}. Below 66 km altitude, the increase of electron density is delayed by about 30 min, indicating that the time taken for neutral oxygen species to build up is a controlling factor in producing the free electrons at these heights. Both these processes are operative between 66 and 70 km altitude. Nighttime profiles of the ratio of negative ion number density to electron number density are deduced, and empirical relationships of electron concentration at heights between 60 and 70 km are determined as a function of simultaneously observed proton flux.

  17. UHF频段上变频器的设计与实现%Design and Implementation of UHF Up- converter

    Institute of Scientific and Technical Information of China (English)

    孙海峰; 刘琦; 岳超

    2013-01-01

    The requirements to up-converter’s indicators such as linear characteristic and spur suppression is very strict, so as not to effect the signal characteristics in the process of up-conversion. The UHF up-converter adopts the dual-conversion scheme to prevent the local oscil ator signals from fal ing in the band. By means of rational al ocation of frequency and level and by use of appropriate electronic devices, the combination interferences resulted by mixing nonlinearity and the output spurs are decreased. The test results show that the scheme is feasible and satisfied with the index requirements.%  为了在上变频过程中不影响信号特性,对上变频器的线性特性和杂散抑制等指标有严格的要求.UHF频段上变频器采用二次变频方案,避免了本振落入信号带宽内,通过合理的频率和电平配置及选用合适的电子器件,减小了混频非线性导致的组合干扰,降低了输出杂散.测试结果表明,方案正确可行,能满足指标要求.

  18. 超高频RFID集聚识别技术的研究%Study on agglomeration recognition of UHF RFID

    Institute of Scientific and Technical Information of China (English)

    童廷洋

    2014-01-01

    集聚识别技术是针对超高频 RFID 高度密集的射频标签无法全部识别的问题,通过采用超高频远距离电子标签、射频识别金属屏蔽效应和交变磁场集聚识别等技术,克服外部标签干扰和内部射频识别空腔效应,降低或减少遮挡盲点和叠加盲点,快速识读全部密集标签,同时不误读任何标签。%Agglomeration recognition technology can fast read all dense label , solve the problem that highly dense UHF tag cannot be all recognition. The technology uses several techniques including ultra high frequency electronic tags , metal shielding effect and alternating magnetic field. The technology overcomes the effects that external tag interference and internal RFID cavity effect , which reduce shading blind spots and superposition blind spot.

  19. 集成于无源UHF RFID标签的高分辨率CMOS温度传感器%A High-Resolution CMOS Temperature Sensor Integrated in Passive UHF RFID Tag

    Institute of Scientific and Technical Information of China (English)

    王倩; 毛陆虹; 张欢; 张世林; 谢生

    2012-01-01

    This article presents a high-resolution CMOS temperature sensor architecture integrated in passive UHF RFID tag. The architecture uses the method of digitalizing and sampling in time-domain. APTAT ( Proportional to absolute temperature) current source and the oscillator inside the tag compose a FT AT oscillator, which generates a pulse whose period is related with absolute temperature. This pulse will be the clock signal of a counter. Within the range of -50 °C ~ 50°C, the period of the pulse is from 1.841 us to 0.426 us. Also, the design uses a digital circuit to deal with the preamble command in order to get a pulse whose period is 200 (is and is absolutely not affected by absolute temperature. This pulse will be the enable signal of the same counter. By means of sampling and counting, we get digital signal with temperature information. The design uses 0. 18 um UMC CMOS process,the supply voltage is 1. 8 V,the DC power dissipation is 789nW,and the post-simulation effective resolution is 0. 332 LSB/°C.%提出一种高分辨率的集成于无源UHF RFID标签的CMOS温度传感器结构.采用时域数字量化的方式,用与绝对温度成正比PTAT( Proportional to Absolute Temperature)电流源和标签内部振荡器构成的PTAT振荡器产生脉冲宽度与温度相关的脉冲信号,作为计数器的时钟信号,在温度-50℃~50℃范围内,脉冲周期从1.841μs~0.426 μs;用数字电路对阅读器发送的帧头命令进行处理得到一个宽度为200 μs的宽脉冲信号,作为计数器的使能信号,该脉冲的宽度完全不受温度影响;通过采样计数,得到包含温度信息的数字信号.本设计采用0.18 μm UMC CMOS工艺,电源电压为1.8V,直流功耗为789 nW,温度传感器后仿的有效分辨率达到0.332 LSB/℃.

  20. Design of District Vehicle Access Control System Based on UHF RFID Technology%基于 UHF RFID 技术的小区车辆门禁系统设计

    Institute of Scientific and Technical Information of China (English)

    赵彦; 张刚

    2016-01-01

    Vehicle management mode in traditional residential quarters mostly rely on guards ,both time‐consuming and labori‐ous ,reliability and accuracy are also not meeting the requirements ,the district’s security is without strong assurance .To solve this thorny problem ,a district vehicle access control system is designed based on UHF RFID technology ,on the basis of the Internet of Things ,and by setting the electronic tag on vehicles ,then the reader is combined to the computer network to achieve the automatic recognition of vehicle license .The model has a fast and efficient characteristics ,scientific and effective way to manage the vehicle within the cell ,the burden on the management staff is reduced ,the lives of residents are facilitated .%传统的住宅小区对进出车辆的管理模式,大部分都是门卫的人工操作,既费时又费力,可靠性和准确度也达不到要求,小区的安全性得不到有力的保证。针对这一棘手问题,提出了基于 U HF RFID 技术的小区车辆门禁系统,在物联网理论的基础上,通过对进出车辆设定电子标签,把读写器和计算机网络相结合,实现了车辆标签牌照的自动识别。该模式具有快速、高效的特点,科学有效地对小区内的车辆进行管理,减轻了管理人员的负担,方便了居民的日常生活。

  1. A 500 kpc HI Extension of the Virgo Pair NGC4532/DDO137 Detected by the Arecibo Legacy Fast ALFA (ALFALFA) Survey

    CERN Document Server

    Koopmann, R A; Haynes, M P; Kent, B R; Balonek, T J; Brosch, N; Higdon, J L; Salzer, J J; Spector, O

    2008-01-01

    We report the discovery of a ~500 kpc HI extension southwest of the Virgo Cluster HI-rich pair NGC 4532/DDO 137, detected as part of the Arecibo Legacy Fast ALFA (ALFALFA) Survey. The feature is the longest and most massive HI tail structure so far found in the Virgo Cluster and, at 1.8 Mpc from M87, the most distant from the main concentration of the intracluster medium. The structure is spatially and spectrally separated into two ridges and is defined by diffuse emission and discrete clumps of mass 2.5 - 6.8 x 10**7 solar masses. All emission is blue-shifted with respect to the NGC 4532/DDO 137 pair emission. Including diffuse emission, the structure has a total mass of up to 7 x 10**8 solar masses, equivalent to ~10% of the system's HI mass. Optical R-band imaging finds no counterparts to a level of 26.5 mag arcsec**-2. The characteristics of the structure appear most consistent with a tidal origin.

  2. The Arecibo Arp 220 Spectral Census I: Discovery of the Pre-Biotic Molecule Methanimine and New Cm-wavelength Transitions of Other Molecules

    CERN Document Server

    Salter, C J; Catinella, B; Lebron, M; Lerner, M S; Minchin, R; Momjian, E

    2008-01-01

    An on-going Arecibo line search between 1.1 and 10 GHz of the prototypical starburst/megamaser galaxy, Arp 220, has revealed a spectrum rich in molecular transitions. These include the ``pre-biotic'' molecules: methanimine (CH$_{2}$NH) in emission, three $v_{2}=1$ direct l-type absorption lines of HCN, and an absorption feature likely to be from either $^{18}$OH or formic acid (HCOOH). In addition, we report the detection of two, possibly three, transitions of $\\lambda$4-cm excited OH not previously detected in Arp~220 which are seen in absorption, and a possible absorption feature from the 6.668-GHz line of methanol. This marks the first distant extragalactic detection of methanimine, a pre-biotic molecule. Also, if confirmed, the possible methanol absorption line presented here would represent the first extragalactic detection of methanol at a distance further than 10 Mpc. In addition, the strong, previously undetected, cm-wave HCN $v_{2}=1$ direct l-type lines will aid the study of dense molecular gas and ...

  3. Topology and Polarisation of Subbeams Associated With Pulsar 0943+10's ``Drifting''-Subpulse Emission I. Analysis of Arecibo 430- and 111-MHz Observations

    CERN Document Server

    Rankin, J M

    2000-01-01

    The ``drifting'' subpulses exhibited by some radio pulsars have fascinated both observers and theorists for 30 years, and have been widely regarded as one of the most critical and potentially insightful aspects of their emission. Here, we report on detailed studies of pulsar B0943+10, whose nearly coherent sequences of ``drifting'' subpulses have permitted us to identify their origin as a system of subbeams that appear to circulate around the star's magnetic axis. We introduce several new techniques of analysis, and we find that both the primary and secondary features in the star's fluctuation spectra are aliases of their actual values. We have also developed a method of tracing the underlying pattern responsible for the observed sequences, using a ``cartographic'' transform and its inverse, permitting us to study the characteristics of the polar-cap emission ``map'' and to confirm that such a ``map'' in turn represents the observed sequence. We apply these techniques to the study of three different Arecibo o...

  4. The Arecibo Legacy Fast ALFA Survey: IX. The Leo Region HI Catalog, Group Membership and the HI Mass Function for the Leo I Group

    CERN Document Server

    Stierwalt, S; Giovanelli, R; Kent, B R; Martin, A M; Saintonge, A; Karachentsev, I D; Karachentseva, V E

    2009-01-01

    We present the catalog of HI sources extracted from the ongoing Arecibo Legacy Fast ALFA (ALFALFA) extragalactic HI line survey, found within the sky region bounded by 9h36m < RA < 11h36m and +08deg < DEC < +12deg. The HI catalog presented here for this 118-deg^2 region is combined with ones derived from surrounding regions also covered by the ALFALFA survey to examine the large scale structure in the complex Leo region. Because of the combination of wide sky coverage and superior sensitivity, spatial and spectral resolution, the ALFALFA HI catalog of the Leo region improves significantly on the numbers of low HI mass sources as compared with those found in previous HI surveys. The HI mass function of the Leo I group presented here is dominated by low-mass objects: 45 of the 65 Leo I members have M_HI < 10^8 Msun, yielding tight constraints on the low-mass slope of the Leo I HI mass function. The best-fit slope is alpha < -1.41 + 0.2 - 0.1. A direct comparison between the ALFALFA HI line det...

  5. PSR J1856+0245: Arecibo Discovery of a Young, Energetic Pulsar Coincident with the TeV Gamma-ray Source HESS J1857+026

    CERN Document Server

    Hessels, J W T; Gaensler, B M; Kaspi, V M; Lorimer, D R; Champion, D J; Lyne, A G; Krämer, M; Cordes, J M; Freire, P C C; Camilo, F; Ransom, S M; Deneva, J S; Bhat, N D R; Cognard, I; Crawford, F; Jenet, F A; Kasian, L; Lazarus, P; Van Leeuwen, J; McLaughlin, M A; Stairs, I H; Stappers, B W; Venkataraman, A

    2008-01-01

    We present the discovery of the Vela-like radio pulsar J1856+0245 in the Arecibo PALFA survey. PSR J1856+0245 has a spin period of 81ms, a characteristic age of 21kyr, and a spin-down luminosity Edot = 4.6 x 10^36 ergs/s. It is positionally coincident with the TeV gamma-ray source HESS J1857+026, which has no other known counterparts. Young, energetic pulsars create wind nebulae, and more than a dozen pulsar wind nebulae have been associated with very-high-energy (100GeV-100TeV) gamma-ray sources discovered with the HESS telescope. The gamma-ray emission seen from HESS J1857+026 is potentially produced by a pulsar wind nebula powered by PSR J1856+0245; faint X-ray emission detected by ASCA at the pulsar's position supports this hypothesis. The inferred gamma-ray efficiency is epsilon_gamma = L_gamma/Edot = 3.1% (1-10TeV, for a distance of 9kpc), comparable to that observed in similar associations.

  6. Research on 1 100 kV GIS Partial Discharge Fault Location Based on UHF Technology%基于特高频法的1100 kV GIS局部放电故障定位研究

    Institute of Scientific and Technical Information of China (English)

    王文浩; 胡锡幸; 郦于杰; 何文林; 徐华; 刘江明

    2015-01-01

    The case that built-in type UHF sensor alarmed after 1 100 kV GIS circuit breaker switching is presented. The fault is located successfully based on the propagation characteristics and pattern recognition techniques of UHF signals, and then attenuation rule of UHF signals in different gas chambers is concluded. By tracking and analyzing the UHF signal amplitude and on-line frequency spectrogram information and de-tecting discharge point by faulty gas chamber disassembly, the above-mentioned diagnosis and analysis is proved correct, providing an effective example for application of UHF-based method in UHV GIS projects. In the final, the paper brings forward some suggestions on field detection of UHF-based method.%针对一起1100 kV GIS开关投切后内置式特高频传感器的报警案例,利用特高频信号的传输特性和模式识别技术成功实现了故障定位,进而得出了特高频信号在不同气室间的衰减规律。跟踪分析故障气室特高频信号幅值和在线谱图信息,通过故障气室解体找到了放电点,验证了之前诊断分析的正确性,为特高频法在特高压GIS工程中的应用提供了有效例证。最后提出了特高频法在现场检测的几点建议。

  7. VHF/UHF波段星载SAR电离层效应研究%The ionospheric effects on spaceborne SAR at VHF/UHF

    Institute of Scientific and Technical Information of China (English)

    赵万里; 梁甸农; 周智敏

    2001-01-01

    星载UHF/VHF波段合成孔径雷达对隐蔽目标有很强的探测能力,在军事和民用中都有重要应用前景,但其实现受到电离层效应的严重限制,文中介绍了此研究方向的现状、主要问题、以及相应的解决方法.

  8. Research of CMOS-compatible-integrated micro solar cell for passive UHF RFID tag%应用于无源UHF RFID标签的CMOS兼容集成微型太阳能电池研究

    Institute of Scientific and Technical Information of China (English)

    侯贺刚; 张世林; 郭维廉; 毛陆虹; 谢生; 韩磊

    2012-01-01

    在标准CMOS工艺下,设计了一种与CMOS工艺兼容的片上集成太阳能电池阵列,通过从外部环境收集光能为UHF射频识别(RFID)标签供电。采用SMIC 0.18μm CMOS工艺制备出太阳能电池阵列,其面积约为0.2mm2;在AM1.5、1 000W/m2、25℃标准测试条件下,测得最大输出功率为10.212μW,短路电流和开路电压分别为28.763μA和0.458V,光电转换效率为5.106%。相对于常规Si太阳能电池复杂的制造工艺,本文太阳能电池阵列与CMOS工艺相兼容,可与电路系统集成从而实现片上供电。%In this paper,the CMOS-compatible micro solar cell arrays with chip-scale designed in standard CMOS process are presented,which will receive solar energy from the environment and supply the UHF radio-frequency-identification(RFID) tag.The solar cell test chip is implemented by SMIC 0.18 μm CMOS technology with approximately 0.2 mm2 active area.The maximum output power obtained at AM 1.5,1 000 W/m2 and 25 ℃ is 10.212 μW,and the short-circuit current and open-circuit voltage are 28.763 μA and 0.458 V,respectively.The photoelectric conversion efficiency is 5.106%.In contrast to the complex manufacture processes for conventional solar cell,the CMOS solar cell is compatible with standard CMOS technology and can be integrated on the same chip to supply energy for the system.

  9. 基于UHF-EGARCH模型的股指期货市场实证研究%Empirical Research on the Stock Index Market Based on the UHF-EGARCH Model

    Institute of Scientific and Technical Information of China (English)

    孙艳; 何建敏; 周伟

    2011-01-01

    This paper investigates the intraday effect and the volatility of the hs300 stock index futures based on the high frequency data. First, we propose the UHF-EGARCH model by adding the price duration into the GARCH model and combing the asymmetry of the volatility. Then, we select three kinds of high frequency data; 1 minute, 10 seconds and 1 second data, and find that there are obvious weekend effect and intraday effect of the absolute yield and the price durations. Most of the intraday effect of the absolute yield present in the W pattern and the intraday effect of the price durations display four patterns: The U pattern, the L pattern, the W pattern and the inverted U pattern, rather than a single pattern. Finally, we further research the short-term volatility after eliminating the intraday effect with the linear spline function, we find that there are obvious clustering and asymmetry in the volatility, in which the effect caused by the bad news is more powerful than those caused by the good news, and we draw the corresponding curve of the asymmetric error term.%利用沪深300股指期货高频数据研究其日内效应和波动性特征.将高频数据所特有的价格持续期引入到GARCH模型中,并考虑到收益率序列波动的非对称性,建立UHFEGARCH模型,分别选取1分钟、10秒钟、1秒钟采集频率的数据进行实证,采用线性样条函数剔除日内效应影响,进一步研究短期波动性,并画出相应的非对称冲击曲线.研究结果表明,基于3种采集频率数据的绝对收益率和价格持续期呈现明显的周末效应和日内效应,绝对收益率的日内效应基本上呈W型,价格持续期的日内效应有U型、L型、W型和倒U型4种形态并存,并不是某种单一的形态;短期波动性具有明显的集聚性和非对称效应,其中坏消息的影响强于好消息的影响.

  10. 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.

  11. 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.

  12. 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

    2016-07-26

    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.

  13. 一种新型VHF/UHF数据链中的时隙分配策略%A novel timeslot assignment algorithm of VHF/UHF data link

    Institute of Scientific and Technical Information of China (English)

    粱爽; 赵伟光

    2012-01-01

    时隙分配技术是VHF/UHF数据链中的一项关键技术,通过它可以提高系统的通信效率。在目前VHF~HF数据链的基础上.提出了一种新的时隙分配高层算法:渐变分配策略,它主要是以固定分配方式为主,以竞争分配和动态分配为辅的一种新型时隙分配策略,兼有固定分配、竞争分配和动态分配的优点,同时又尽可能克服它们的缺点,以最小代价换来最大成效。%The timeslot allocation algorithm is one of important technologies on VHF/UHF Data Link to improve the communication efficiency of the system. Focus on the characteristics of VHF/UHF Data Link, the paper proposes a new algorithm, which named after Shading Allocation Strategy. It mainly gives priority to Fixation Allocation and minority to Competition Allocation and Dynamic Allocation. The strategy has concurrently advantages of Fixation, Competition and Dynamic Allocation, and avoids their disadvantages as much as possible to exchange minimum cost for maximum effect.

  14. 一种超高频RFID读写器的设计与实现%Design and implementation of UHF RFID reader

    Institute of Scientific and Technical Information of China (English)

    蒋冠宇; 蒋泰; 邓家明; 张余明

    2015-01-01

    目的:设计一种多标签超高频RFID读写器并实现其读写功能。方法:根据ISO18000-6短程通信接口协议,基于arm7芯片实现软件数据处理功能,采用外围硬件设计实现整个系统功能。结果:读写器能够同时读取多枚标签并且有效避免冲突发生,读取的数据可以通过服务器做进一步处理。结论:该读写器工作正常,具有比较大的应用前景。%Objective:A multi-tag UHF RFID reader is designed and realized.Method:According to ISO18000-6 protocol of short range communication, data processing is realized based on ARM7 chips and peripheral hardware is designed to make the system workable.Result:The reader can read multiple tags at one time and effectively avoid collision. The data read can be sent to servers for further processing.Conclusion:This UHF RFID reader functions properly and it has a broad application prospect.

  15. SEMICONDUCTOR INTEGRATED CIRCUITS: A fully integrated UHF RFID reader SoC for handheld applications in the 0.18 μm CMOS process

    Science.gov (United States)

    Jingchao, Wang; Chun, Zhang; Zhihua, Wang

    2010-08-01

    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 × 3.8 mm2 including pads.

  16. 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

  17. 用于银行纸币管理系统的UHF-RFID标签天线设计%Design of an UHF-RFID tag antenna used for the paper money management system in the bank

    Institute of Scientific and Technical Information of China (English)

    田春胜; 周凯; 由丽; 管有林

    2015-01-01

    A miniaturized ultra high frequency ( UHF) band tag antenna is presented, which is used for paper mon⁃ey management system in the bank. Using the folded dipole structure can effectively reduce the size of the antenna and miniaturize the design. The antenna has a bar and a T⁃match loop, realizing a good impedance matching to chip. The antenna is attached to the paper⁃based material;on the one hand, the soft paper⁃based material can be bent, which is conductive to bundling the paper money;on the other hand, the recyclable paper⁃based material can reduce environmental pollution. Input impedance of the proposed antenna is 32. 5+j110 Ω, which is conjugate⁃matched up with an Impinj Gen2 chip with impedance of 33-j112Ωat 915 MHz. The simulation result shows that the antenna has good omni⁃directivity, and the maximum gain at 915 MHz is 2. 33 dBi, the maximal theoretical reading distance is approximately 10m. The antenna proposed in this paper can be effectively applied in practice.%提出了一种特高频段的用于银行纸币管理系统的小型化标签天线。天线采用折叠偶极子结构,可有效地减小天线的尺寸,实现小型化的设计。通过附加横条和T型阻抗匹配结构,实现了天线与芯片之间良好的阻抗匹配。天线贴附在纸基材料上,一方面纸基材料柔软可弯折,利于对纸币进行捆绑;另一方面,纸基材料可回收利用,减少环境污染。针对Impinj的Gen2芯片,芯片的阻抗为33-j112Ω,天线在915 MHz工作频率下的输入阻抗为32.5+j110Ω,两者实现了较好的阻抗匹配。仿真结果表明:天线具有很好的全向性,并且在915 MHz时的最大增益为2.33 dBi,最大理论读取距离约为10 m,可以有效地应用到实际生活中。

  18. Uhf RFID Construction Elevator Power Failure Detection Algorithm Simulation%超高频RFID施工升降机电源故障检测算法仿真

    Institute of Scientific and Technical Information of China (English)

    蒋琳琼; 周顺先

    2014-01-01

    Research uhf RFID construction elevator power failure accurate detection problem. This paper put for-ward a fault feature based on correlation residual compensation algorithm of uhf RFID construction elevator power fault detection method. The relationship between the fault signal characteristics was calculated, and the fault signal of the error was compensated. According to the fault characteristic similarity, weccalculated the fault space position, so as to realize the uhf RFID construction elevator power fault detection. The experimental results show that the algorithm can effectively improve the accuracy of the power supply fault detection.%研究超高频RFID施工升降机的电源故障检测问题。施工现场的电源大多是通过母线并入现场配电网络,而升降机的分布式电源直接并入配电网,线路中间增加多余的支路,对线路两侧的电流大小、方向造成影响,容易造成故障信号的波动。传统的故障检测方法很难对这种随机波动进行准确分类,导致检测的准确性较低。为此,提出基于故障特征相关性残差补偿的超高频RFID施工升降机电源故障检测算法。首先,计算故障信号特征之间的相似性,从而对故障信号中的误差进行补偿;然后根据故障特征相似性,计算故障空间位置,从而实现超高频RFID施工升降机电源故障检测。实验结果表明,利用改进的算法能够有效提高电源故障检测的准确性。

  19. The Experimental Equipment Management System Based on UHF RFID%基于超高频RFID的实验仪器管理系统的开发

    Institute of Scientific and Technical Information of China (English)

    吴晓蕾; 赵航涛

    2013-01-01

    为了提高学校实验设备的管理水平,采用软件工程的方法,运用RUM900+超高频RFID阅读模块,使用C#完成了实验室仪器管理系统的开发,在学校实验设备仓库进行了实验,系统能够完成设备的自主借用和归还管理,达到了设计目的.%In order to improve the management level of laboratory equipments, this study developed a laboratory equipment management system by using the RUM900+ UHF RFID reading module with C# programming language. The system has been tested at the school experimental equipment warehouse, and the results showed that it could complete the equipment borrowing and returning process independently. The design objectives have been fully achieved.

  20. 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.

  1. SEMICONDUCTOR INTEGRATED CIRCUITS: A current-mode voltage regulator with an embedded sub-threshold reference for a passive UHF RFID transponder

    Science.gov (United States)

    Zhongqi, Liu; Chun, Zhang; Yongming, Li; Zhihua, Wang

    2010-06-01

    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 °C, 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.

  2. 超高频RFID技术在图书馆的应用分析%Analysis on The Application of UHF RFID Technology in Libraries

    Institute of Scientific and Technical Information of China (English)

    赵文彬

    2011-01-01

    面对在现有图书馆中已经成熟应用的高频RFID技术,超高频RFID技术有哪些优点和不足,大范围推广应用超高频技术存在什么问题,现阶段图书馆应用RFID技术的合理步骤应是怎样,将是本文主要探讨分析的内容。%This paper analyzes the application of RFID technology in the library,discusses the advantages and disadvantages between HF and UHF RFID technology.And then,researches on the problems in applying RFID technology for library.At last,puts forward the steps for library to apply RFID technology.

  3. Research and Design of UHF RFID Reader%超高频射频识别读写器的研究与设计

    Institute of Scientific and Technical Information of China (English)

    李宝山; 李革

    2011-01-01

    超高频射频识别系统具有存储容量大、读写速度快、识别距离远和可同时读写多个电子标签等特点,已经在众多领域得到了广泛的应用。为了满足市场需求,文章对超高频读写器的内部结构进行了研究,并提出了一种基于ARM的超高频射频识别系统读写器的设计方案。文中从硬件和软件两个方面对读写器的设计进行了阐述,给出了读写器的设计结构、工作流程以及相关的软件流程图。实际应用结果表明,该读写器具有读写速度快、读写效率高、识别距离远等优点,可以满足市场需求。%The system of UHF RFID has the advantages such as storage capacity, read and write speed, recognition distance, and can read or write multiple RFID tags simultaneously, which has been applied widely in many fields. In order to meet market requirements, this paper proposes a design project of a UHF RFID system interrogator based on ARM. In this paper, two aspects of hardware and software design of the interrogator are described, the design gives the structure of interrogator, work processes and the related flow chart of software. The practical results show that the interrogator has the advantages of read and write speed, efficient read-write, recognition distance and so on, which can meet market requirements.

  4. Research and Design of UHF RFID reader%超高频射频识别读写器的研究与设计

    Institute of Scientific and Technical Information of China (English)

    李宝山; 李革

    2011-01-01

    The system of UHF RFID has the advantages such as storage capacity, read and write speed, recognition distance, and can read or write multiple RFID tags simultaneously, which has been applied widely in many fields. In order to meet market requirements, this paper proposes a design project of a UHF RFID system interrogator based on ARM. In this paper, two aspects of hardware and software design of the interrogator are described, the design gives the structure of interrogator, work processes and the related flow chart of software. The practical results show that the interrogator has the advantages of read and write speed, efficient read-write, recognition distance and so on, which can meet market requirements.%超高频射频识别系统具有存储容量大、读写速度快、识别距离远和可同时读写多个电子标签等特点,已经在众多领域得到了广泛的应用。为了满足市场需求,对超高频读写器的内部结构进行了研究并提出了一种基于ARM的超高频射频识别系统读写器的设计方案。从硬件和软件两个方面对读写器的设计进行了阐述,给出了读写器的设计结构、工作流程以及相关的软件流程图。实际应用结果表明,该读写器具有读写速度快、读写效率高、识别距离远等优点,可以满足市场需求。

  5. Near field detection core technology for UHF RFID tag conformity%超高频RFID标签一致性的近场检测技术

    Institute of Scientific and Technical Information of China (English)

    童廷洋; 马振洲

    2013-01-01

    The conformity of UHF RFID tags directly affects the recognition rate and accurate rate of data acquisition in a RFID system. We used the RSSI (Received Signal Strength Indicator) technique and mathematical statistics to collect reflected signal strength of tags and set the standard deviation threshold as parameters for tag conformity detection. We also developed the bending dipole near field antenna to read RFID tags in 0.1mm distance. Using shielding effect, we set a dotting identification device on full automatic reel-type RFID tag sets and marked them in batch to achieve high speed conformity detection of flexible UHF RFID tags.%超高频RFID标签一致性直接影响RFID系统中采集数据的识别率和准确率.采用接收信号强度指示RSSI(Received Signal Strength Indicator)技术及数理统计,采集标签反射信号强度,设定标准差阈值,作为标签一致性检测参数.研制弯折偶极子近场天线,实现0.1 mm近距离标签识读.利用屏蔽效应,在全自动卷筒式RFID标签套装上设置打点标识机构,对标签批量标记,可实现对柔性超高频RFID标签的高速、批量一致性检测.

  6. 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)

  7. 基于UHF RFID技术的电能智能计量系统电力设备的全生命周期管理研究%Research on RFID-based Life-cycle Management of Electric-energy Intelligent Measuring System' Electrical Equipment

    Institute of Scientific and Technical Information of China (English)

    肖勇; 孙勇; 孔政敏; 方彦军

    2013-01-01

    In view to the fast and accurate demand of the electricity to power equipment intelligent measuring system management, the paper constructed a life - cycle management system based on UHF - RFID technology. It established the system structure and operating process and expounded the power equipment of the performance evaluation system. It studied the tags based on UHF RFID and the UHF RFID system application model based on Web service. It solved the problems of each stage split and the problem of unscientific and effective assessment system in the traditional electric power equipment management way.%针对电能智能计量系统对电力设备管理快速准确的需求,构建一种基于UHF RFID(超高频射频识别)技术的全生命周期管理系统,建立该系统的体系结构和运行流程并阐述电力设备的性能评估体系,研究基于UHF RFID的电子标签、基于Web Service(网络服务)的UHF RFID系统集成应用模型,解决传统电力设备管理方式中各阶段被割裂、无科学有效评估体系的问题.

  8. Dual-Beam Atom Laser Driven by Spinor Dynamics

    Science.gov (United States)

    Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David

    2007-01-01

    An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.

  9. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Theppakuttaikomaraswamy, Senthil P. [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 μm and the spacing between holes (the distance between the centers) is 100 μm. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the interferometer measurements with a very high accuracy. The experimental results demonstrate the feasibility of applying this system in industries that require precise measurements where cost of making as well as accuracy both cannot be compromised.

  10. Decomposition of the MANET steel under dual-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wanderka, N. [Hahn-Meitner-Institut Berlin (Germany); Camus, E. [Hahn-Meitner-Institut Berlin (Germany); Naundorf, V. [Hahn-Meitner-Institut Berlin (Germany); Keilonat, C. [Hahn-Meitner-Institut Berlin (Germany); Welzel, S. [Hahn-Meitner-Institut Berlin (Germany); Wollenberger, H. [Hahn-Meitner-Institut Berlin (Germany)

    1996-02-01

    Decomposition of the MANET steel was observed by means of atom probing after 300 keV Fe{sup +} ion irradiation to 50 dpa and simultaneous implantation of 15 keV He{sup +} ions at a rate of 200 appm/dpa. At irradiation temperatures of 673 and 698 K weak periodical variation of the chromium concentration was observed. At irradiation temperatures of 723 and 773 K clusters with chromium concentration of up to 25 at% were detected. (orig.).

  11. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Senthil P. Theppakuttaikomaraswamy

    2001-12-31

    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 {micro}m and the spacing between holes (the distance between the centers) is 100 {micro}m. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the interferometer measurements with a very high accuracy. The experimental results demonstrate the feasibility of applying this system in industries that require precise measurements where cost of making as well as accuracy both cannot be compromised.

  12. AZ31B镁合金/不锈钢异种合金双光束激光熔钎焊接特性%Welding Characteristics of AZ31B Magnesium Alloy/Stainless Steel Dissimilar Alloys by Dual Beam Laser Welding-Brazing Process

    Institute of Scientific and Technical Information of China (English)

    李俐群; 郭伟; 檀财旺

    2012-01-01

    以镁基焊丝为填充材料,采用双光束激光熔钎焊的方法对AZ31B镁合金/不锈钢的焊接特性进行了研究.分析了不同工艺参数对焊缝成形、接头力学性能和断裂行为的影响.结果表明,采用双光束进行填丝熔钎焊能够获得较满意的外观成形,无明显缺陷,焊接工艺范围较宽.接头拉伸均断裂于熔化焊的镁侧焊缝及热影响区(HAZ),最大剪切强度为193 MPa,达到镁合金母材强度的71%.组织分析发现焊缝和HAZ的晶粒粗大,成为接头的薄弱部位,是接头失效的主要原因.钎焊侧界面发生了冶金反应,界面处生成1~2 μm的反应层.%AZ31B magnesium alloys and 201 stainless steel are joined by laser welding-brazing process with Mg based filler. The welding characteristics including influence of processing parameters on weld appearance, mechanical properties and fracture behavior are studied- Results indicate that satisfactory appearance of welds without evident defects can be achieved by dual beam laser-brazing process with filler. A wide processing window is obtained. The tensile-shear test shows that fracture occurred at two places, weld seam and heat affect zone (HAZ) at the welding side of Mg alloys. The maximum shear strength can reach 193 Mpa, which is 71% of that of Mg base metal. The microstructure observed indicates that seam and HAZ are weak parts, which results in failure of joint due to presence of coarse grains. Metallurgical reaction occurs at the brazing side, where reaction layer with thickness of 1~2 μm forms.

  13. 基于超高频法的GIS局部放电类型判断方法%Judgment of Partial Discharge Types in GIS Based on UHF Method

    Institute of Scientific and Technical Information of China (English)

    李国伟; 章涛; 王俊波; 刘卫东

    2013-01-01

    笔者介绍了使用清华大学M系列超高频(UHF)传感器在GIS局部放电中的应用,针对GIS局部放电不同种类放电间隙给出了示波器图谱,结合现场几起实例证明该方法判断方便、准确、有效.%This paper introduces GIS partial discharge detection by M-series ultra-high frequency (UHF) sensors made by Tsinghua University. The principle, characteristics and waveforms of GIS partial discharge under different discharge gaps are provided. Practical examples demonstrate that the method is convenient, accurate and effective.

  14. Application of UHF Cable Fault Detection in Precise Positioning%特高频检测法在电缆故障精确定位中的应用

    Institute of Scientific and Technical Information of China (English)

    岳文超; 张伟

    2015-01-01

    简要介绍了电缆故障的定位和特高频检测法(简称UHF)的工作原理,结合当前电力工作的实际需要,研究了如何将冲击放电法与特高频放电检测法结合起来,从而精确定位电缆故障,并通过实例证明此方法是有效、可行的。%This paper introduces the cable fault location and UHF detection method works, combined with the actual needs of the current electrical work, study how the impact of the discharge method and UHF discharge detection method combined to accurately locate cable faults, and an example to prove this method is effective and feasible.

  15. Clinical Efficacy Comparison between UHF Instrument and Freezing Method in Treating Eyelid Xanthoma%超高频仪与冷冻法治疗眼睑黄色瘤的临床疗效比较

    Institute of Scientific and Technical Information of China (English)

    李维鑫; 王彩华

    2009-01-01

    Objective To observe and eompare the efficacy of UHF instrument and freezing method in treating eyelid Xanthoma and provide reference for clinical practice.Methods 53 eyelid Xanthoma patients were divided into UHF treatment group and freezing treatment group and compare their curative effects.Results Among the 17 patients who received UHF treatment,15 have been cured,2 had excellent effects and the total effective rate was 100% ;among the 36 patients receiving freezing treatment,18 have been cured,13 had excellent effects and 5 have gotten no effects and the total effective rate was 86.11%.The difference between two groups was significant.Conclusion Compared with freezing method,UHF treatment has better efficacy.%目的 观察比较运用超高频治疗仪与冷冻涛对眼睑黄色瘤的治疗疗效,为临床治疗提供依据.方法 将53例眼睑黄色瘤患者分为超高频仪治疗组和冷冻法治疗组,观察各组的疗效.结果 17例运用超高频治疗仪治疗眼睑黄色瘤,痊愈15例,显效2例,总有效率100%.36例运用冷冻法治疗眼睑黄色瘤,痊愈18例,显效13例,无效5例,总有效率86.11%.两种方法比较.差异有统计学意义.结论 采用超高频治疗仪治疗与冷冻法比较,治疗效果更为满意.

  16. 基于VxWorks操作系统如何实现宽带超短波电台隧道%How to Implement a Kind of UHF Radio Tunnel Based on the Real Time Operating System VxWorks

    Institute of Scientific and Technical Information of China (English)

    赵明; 屈晔彬; 张日飞

    2012-01-01

    A kind of tunnel method based on VxWorks protocol stack is introduced. Combining with the application of UHF radio, the channel technology principle and realization process are Mainly discussed,and the key code of the example program is given. The practice shows that the method is simple in design, reliable performance,good effect, and solve a series of problems because of "non-standard"in UHF radio in data communication,and meet the different application occasions of UHF requirements.%介绍了一种基于VxWorks协议栈的隧道的技术,并结合其在宽带超短波电台中的应用,详细讨论了实现隧道技术的原理和过程,并给出了程序实例的关键代码.实践表明,该方法设计简单,性能可靠,效果良好,解决了宽带超短波电台数据通信由于“非标”所带来的一系列问题,满足了不同应用场合下对宽带超短波电台的需求.

  17. Why Gravitational Wave Science Needs Pulsar Timing Arrays And Why Pulsar Timing Arrays Need Both Arecibo and the GBT: A Response to the NSF-AST Portfolio Review from the NANOGrav Collaboration

    CERN Document Server

    ,

    2012-01-01

    Gravitational waves (GWs) are ripples in space-time that are known to exist but have not yet been detected directly. Once they are, a key feature of any viable theory of gravity will be demonstrated and a new window on the Universe opened. GW astronomy was named as one of five key discovery areas in the New Worlds, New Horizons Decadal Report. Pulsar timing probes GW frequencies, and hence source classes, that are inaccessible to any other detection method and can uniquely constrain the nonlinear nature of General Relativity. Pulsar timing is therefore a critical capability with its own discovery space and potential. Fulfilling this capability requires the complementary enabling features of both the Green Bank Telescope (GBT) and the Arecibo Observatory.

  18. 电力电缆局部放电的高频与特高频联合检测%Partial discharge combination detection with HF and UHF method for power cables

    Institute of Scientific and Technical Information of China (English)

    陈庆国; 蒲金雨; 丁继媛; 李昊; 孙建涛; 张书琦

    2013-01-01

    In order to carry out an on-line partial discharge detection for the after-laying power cables and suppress interference occurring in the on-site measurement, the combination method with HF(High Fre quency) and UHF (Ultra Frequency) measurement is proposed, and the on-line partial discharge detec tion system for power cables is established. The system consists of HF and UHF sensor, signal condition ing units, date-acquisition units and PC software, and the impulse interference was removed through mu tual identification between the HF and UHF signal. Meanwhile the interference suppression algorithm of multi-cycle superimposition based on complex wavelet was put forward. The test results for defect cable show that the system can effectively detect the HF and UHF signals of partial discharge with the sensitivity lower than 10 pc, and the processing results for measured data show that the proposed method can sup press the interference well.%为了对已敷设的电力电缆进行局部放电在线检测,并抑制现场测量时的干扰,采用高频(HF)与特高频(UHF)联合检测的方法,建立一套局部放电在线检测系统.该系统主要由HF和UHF传感器、信号调理单元、数据采集系统和上位机软件组成,通过HF信号和UHF信号的相互鉴别来去除脉冲型干扰信号.同时根据干扰信号和局部放电信号在频带及工频相位上的分布特点,提出基于复小波的多周期叠加干扰抑制算法.对缺陷电缆的试验结果表明,该系统能有效检测到局部放电的HF信号和UHF信号,局部放电检测灵敏度小于10 pc;对局部放电采集数据的处理结果表明,所提出的干扰抑制策略可很好地消除测量时的干扰信号.

  19. Research on fourth-order Hilbert fractal antenna for UHF online monitoring of partial discharge in power transformers%变压器局部放电超高频在线监测天线研究

    Institute of Scientific and Technical Information of China (English)

    沈鑫; 束洪春; 曹敏; 李剑; 翟少磊; 张林山; 林中爱

    2016-01-01

    Ultra-High-Frequency (UHF) method for detection of partial discharge (PD) has been widely appreciated and studied. It can effectively avoid the low-frequency electromagnetic interference and has the advantage of high sensitivi-ty. Mostly, the UHF antennas used for PD detection have large size, and the characters are narrow frequency pand, this paper designs a Hilbert fractal antenna with multi-frequency and small size for UHF PD online monitoring of transform-er. In the existing basic principle of fourth-order Hilbert four-order fractal antenna technology, the planar antenna is mod-eled by Ansoft Designer. Based on simulation calculation, geometric parameters of the antenna were selected and the fourth order Hilbert fractal antenna was designed. The partial discharge UHF signal of four typical defects for oil-paper insulation was measured by the optimized fourth order Hilbert fractal antenna designed in the laboratory. Experimental results show that the designed antenna is qualified for online PD UHF monitoring.%针对传统局部放电超高频检测天线频带窄、尺寸大的缺点,设计了一种用于在线监测变压器局部放电的多频带、尺寸小的超高频天线。通过研究了分形理论和天线测量原理,在现有四阶Hilbert分形曲线的技术基础上,利用Ansoft Designer电磁场仿真软件建立天线模型,并通过仿真计算,优化配置了天线的几何参数,设计制造了平板结构的四阶Hilbert分形局放超高频监测天线。利用设计的四阶Hilbert分形天线对四种典型油纸绝缘缺陷进行局部放电超高频信号监测,并采用文中设计的天线与现有技术的三阶Penao分形天线、三阶Hilbert分形天线在实验室进行局部放电对比测量,分析了天线实测效果,实验结果表明该天线能够有效应用于变压器局部放电超高频在线监测。

  20. A 12 dB 0.7 V W CMOS LNA for 866 MHz UHF RFID Reader

    Directory of Open Access Journals (Sweden)

    Jie Li

    2010-01-01

    Full Text Available The design of a narrow-band cascode CMOS inductive source-degenerated low noise amplifier (LNA for 866 MHz UHF RFID reader is presented. Compared to other previously reported narrow-band LNA designs, in this paper the finite ds  (=1/0 effect has been considered to improve the nanometric design, achieving simultaneous impedance and minimum min noise matching at a very low power drain of 850 W from a 0.7 V supply voltage. The LNA was fabricated using the IBM 130 nm CMOS process delivering a forward power gain (21 of ≈12dB, a reverse isolation (12 of ≈−34dB, an output power reflection (22 @866 MHz of ≈−25dB, and an input power reflection (11 @866 MHz of ≈−12dB. It had a minimum pass-band of around 2.2 dB and a third-order input referred intercept point (IIP3 of ≈−11.5dBm.

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

    Institute of Scientific and Technical Information of China (English)

    Feng Peng; Zhang Qi; Wu Nanjian

    2011-01-01

    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 (Σ△) 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 ℃/0.5 ℃ (-1.0 ℃/1.2 ℃) in the operating range from 5 to 15 ℃ in high resolution mode (-30 to 50 ℃ in low resolution mode).The resolution of the sensor achieves 0.02 ℃ (0.18 ℃) in high (low) resolution mode.

  2. 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.

  3. Effects of Liquid on Performance of UHF RFID Tag%液体对超高频RFID标签性能影响研究

    Institute of Scientific and Technical Information of China (English)

    柳权; 何怡刚

    2011-01-01

    The UHF RFID tag is effected by the environment,especially liquid.Theory analyzing and test experiment,were used to study the effect of liquid on RFID tag.Changes of performance parameters were tested in liquid environment by using the RFID system test platform,and studied based on electromagnetic field simulation software HFSS Ansoft.The results show that the fluid near the RFID system can absorb electromagnetic wave,reduce the radiation efficiency of the tag antenna,and lead to impedance match of antenna gets changed.%超高频RFID标签受环境,尤其是液体的影响很大.通过理论分析结合实验测试,研究了液体对超高频RFID标签的影响.使用RFID系统测试平台测试了液体环境下标签性能参数的变化,并基于电磁场仿真软件HF-SS Ansoft做了仿真研究.结果表明,RFID系统附近的液体能吸收电磁波,使标签天线辐射效率降低,同时引起天线失谐.

  4. 集装箱表面的超高频RFID标签天线设计%Design of UHF RFID Tag Antenna Used in Container

    Institute of Scientific and Technical Information of China (English)

    王平; 文光俊

    2011-01-01

    This paper presented a UHF RFID tag antenna used in container and analyzed the effect of the distance between antenna and metal plates and size of metal planes on antenna parameters in detail. It is demonstrated that by selecting the distance between antenna and metal planes and considering real environment properly, detection distance can meet requirement, and gain of the antenna will be enhanced as increase the size of metal plane, however there is a little effect on match of antenna. Therefore, the antenna is suitable for application as container RFID tag antenna.%提出了一款用于集装箱上的超高频RFID标签天线.从实际制作角度详细分析了天线与金属板的不同距离和金属板不同尺寸对天线参数的影响.结果表明,通过适当选取天线与金属板的距离以及联系实际的使用环境,其阅读距离基本满足要求,并且金属板尺寸的增大,使天线的增益也随着增大,但对天线的匹配影响较小,适合集装箱上RFID标签天线的应用.

  5. Performance Characterization Method of Partial Discharge UHF Sensor Based on Time Domain Parameters%基于时域参数的局部放电特高频传感器性能表征方法

    Institute of Scientific and Technical Information of China (English)

    陈孝信; 钱勇; 盛戈; 江秀臣

    2015-01-01

    特高频(ultra-high frequency,UHF)传感器的时域输出信号对局部放电宽带检测系统的检测和定位结果具有显著影响,因此评估传感器检测性能时,若能从其时域输出特性出发,将更贴近于宽带检测系统的工程需求。现有的有效高度表征体系不适用于具有非平坦群时延的特高频传感器,在描述传感器时域输出特性时具有局限性。提出了一种基于时域参数的特高频传感器的性能表征方法,通过构造解析脉冲响应函数,从中提取包络峰值、包络宽度和振荡时间三种时域参数,用于描述传感器在局部放电脉冲信号下时域输出波形的峰峰值、上升时间和振荡。设计了有效高度幅频特性与相频特性的测试系统并给出时域参数的测试方法。通过比较两种传感器的时域参数测试结果和实际检测结果对该表征方法进行了检验。研究结果表明:该表征方法能有效地反映UHF传感器的时域输出特性,弥补了现有方法的不足。%For wide-band partial discharge (PD) detection systems, the time domain output signals of an ultra-high frequency (UHF) sensor significantly affect the results of PD detection and location. Therefore it would be more practical for wide-band PD detection systems if the performance of a UHF sensor is evaluated in terms of its time domain output characteristics. The effective height characterization system currently used has its limitation when the sensor has a non-flat group delay. A performance characterization method of UHF sensors based on time domain parameters is therefore proposed. Three time domain parameters extracted from the analytic impulse response, i.e. the peak value of the envelope, the envelope width and the ringing duration, are applied to describe the peak-peak value, the rise time and the oscillation of the output signal of a UHF sensor detecting PD. A measurement system of the sensor effective height, as

  6. 利用Arecibo射电望远镜河外21-cm巡天数据进行中性氢吸收线的探测研究%HI Absorbers from Arecibo Legacy Fast ALFA Survey

    Institute of Scientific and Technical Information of China (English)

    吴忠祖; HAYNES Martha P; GIOVANELLI Riccardo; 朱明; 陈如荣

    2015-01-01

    利用Arecibo射电望远镜40%的ALFALFA (Arecibo Legacy Fast Arecibo L-band Feed Array)河外中性氢巡天数据,探讨了进行中性氢吸收线“盲寻”的过程与方法,并给出了搜寻吸收线的一些初步结果:(1)探测到的中性氢吸收源的数量共有10个,其中5个为文献中已知源,其余新发现的吸收线源需要进一步的研究与证实.(2)利用探测灵敏度给出了探测区域中性氢柱密度的上限,这些上限的频率统计分布显示阻尼莱曼α吸收线系统(DLAs)中的中性氢气体的平均自旋温度与覆盖因子的比值Ts/f很可能大于500K.射电干扰与驻波是影响Arecibo河外中性氢吸收线探测的两个重要因素,也将进行一定的分析以及讨论相应的解决方法等.正在建设中的500m口径射电望远镜FAST (The Five-hundred-meter Aperture Spherical Telescope)与Arecibo射电望远镜属于相似类型,但在灵敏度、频带宽度、观测天区范围等方面都将有较大的提高,结合目前的研究进展对将来FAST在中性氢吸收线方面的研究也给出了一定的展望.

  7. 油浸变压器局放UHF电磁波传播特性仿真研究%Simulation of UHF Electromagnetic Wave Propagation for Oil-immersed Transformers with Partial Discharge

    Institute of Scientific and Technical Information of China (English)

    刘明军

    2011-01-01

    大型油浸式电力变压器结构复杂·在UHF电磁波信号传播过程中给放电量标定、局放源定位等带来难度,基于实际运行变压器结构构建精确的仿真模型,利用数值仿真技术探讨了局放UHF电磁波信号受油纸复合绝缘反射、折射及金属导体的反射、吸收表减特性,研究了检测信号强度与局放源和超高频传感嚣的位置关系,并对比分析了不同部位、不同类型放电的时域、频谱及能量累积特性,为变压器局放超高频在线监测奠定了基础.%The structure of large oil-immersed transformer is very complicated. Therefore, it is difficult for discharge calibration and location of partial discharge source in process of ultra high frequency (UHF) electromagnetic waves propagation. The exact simulation model is established with actual transformer structure. Then the effects of internal components (reflection and refraction yielded by compound insulating oiled paper, metallic conductor reflection and absorption attenuation) on the propagation characteristics of UHF electromagnetic wave are discussed through the numerical simulation technique. At the same time, the position relationship between signal intensity, discharge source and ultra high frequency sensor is studied. Finally, the time domain, spectrum and cumulative energy characteristics of different position and type discharge are comparative analysis. Thus, the study has made significantly contributions to the on-line monitoring of UHF transformers with partial discharge.

  8. 基于RFID UHF频段的车辆防拆无源电子标签分析与设计%Analysis and design of UHF tamper-proof passive RFID ceramic tag for vehicles

    Institute of Scientific and Technical Information of China (English)

    邱方; 杨律青; 丁朝; 黄韡; 王太平

    2013-01-01

    To achieve the purpose of convenient, accurate and fast vehicles management, and apply RFID, the core tech-nology of IOT, in the field of intelligent transportation, the paper presents a design method of UHF RFID tag, which is a vehi-cle tamper proof ceramic electronic label based on the theory and design method of tags. A detailed analysis of tag parameters is made in the paper. An UHF RFID tag was produced and identified as patents for utility mode] by the State Intellectual Property Office of China. The simulation results based on the software HFSS verify the effectiveness of the design. The tag has stable per-formance, higher sensitivity and tamper resistance, and meets the design requirements of the UHF RFID tag.%为更好地将物联网的核心技术RFID应用于智能交通领域,达到更方便、更准确和更快捷地管理车辆的目的,从电子标签的理论开始,论述了电子标签的设计方法,详细分析了电子标签相关的参数,并采用电磁仿真软件HFSS对标签进行了仿真并加工出一款UHF频段RFID车辆无源陶瓷防拆电子标签,该标签已经被中国国家知识产权局认定为实用新型专利,仿真结果与测量结果表明,该标签性能稳定、接收灵敏度高,并且具有防拆性,达到UHF频段RFID电子标签的设计要求.

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

    Science.gov (United States)

    Peng, Feng; Qi, Zhang; Nanjian, Wu

    2011-11-01

    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.

  10. Analysis and improvement for UHF RFID reading region in real environments%无源超高频RFID系统识别区域分析及优化

    Institute of Scientific and Technical Information of China (English)

    佐磊; 何怡刚; 李兵; 朱彦卿; 方葛丰

    2012-01-01

    The reading region of ultra high frequency radio-frequency identification (UHF RFID) system is affected by polarization mis- match, reader antenna height, coherent interference and so on. Based on the principles of RFID technology and ray-tracing method, a complete propagation model in real environments is derived. Utilizing recognition rate of target region (RRTR), a method of evalualing the performances of a system is presented. In order to obtain the maximization of RRTR, two solutions including tag diversity and phase switch are proposed, which combines the theories of electromagnetic propagation and coherent interference suppression. The values of RRTR under different parameters are measured in outdoor and indoor environments with a commodity hardware. The measurement results show that the values of RRTR can be enhanced by 10% and 7.6% with the two solutions respectively.%基于射频识别技术原理及射线跟踪理论,导出了实际环境中射频识别系统完整传播链路模型.提出基于目标区域识别率的系统性能评估方法,并讨论了其主要影响因素.结合电磁波传播理论及相干干扰抵消原理,提出标签集及相位开关目标区域识别率优化方法.在室内多径环境下,测试了采用标签集及相位开关优化方法的目标区域识别率.测试结果表明,两种方法下的系统目标区域识别率分别提高10%和7.6%.

  11. 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.

  12. A Passive NCITS 256 UHF RFID Transponder%一种NCITS 256协议超高频无源射频识别标签

    Institute of Scientific and Technical Information of China (English)

    刘忠奇; 孙旭光; 白蓉蓉; 张春; 李永明; 王志华

    2008-01-01

    设计了一种符合NCITS 256协议的无源超高频射频识别标签.标签携带2kbit的标准商用EEPROM.在读卡器发射功率为915MHz 4W EIRP的情况下,芯片的读距离为1.5m,写距离为0.3m.芯片在SMIC 0.18μm EEPROM CMOS工艺下流片实现,面积为1mm×1mm.标签使用Dickson倍压电路从读卡器发射的电磁波中提取能量.Dickson倍压电路使用肖特基管实现,转换效率为25%.%This paper presents a passive UHF radio frequency identification (RFID) transponder with 2k bit standard commercial EEPROM in compliance with the NCITS 256 protocol. The communication range is 1.5m for the read operation and 0.3m for the write operation with 4W effective isotropic radiated power (EIRP) at 915MHz. The integrated IC is implemented in SMIC 0.18μm EEPROM CMOS technology. The die size is 1mm × 1mm. The energy of the tag is harvested from RF electromagnetic waves transmitted by the reader with the help of a Schottky diode rectifier and achieves 25% power efficiency.

  13. Study on new type of UHF sensor for partial discharge detection in transformer%新型变压器局放监测特高频传感器的研究

    Institute of Scientific and Technical Information of China (English)

    朱超杰; 王友臣; 朱琪; 尹毅

    2013-01-01

    近年来,特高频法监测变压器内部局部放电得到了广泛的关注,而特高频传感器性能的优劣直接决定着特高频信号的接收.介绍并设计了一种新型变压器局部放电特高频传感器--Goubau天线,研究了阻抗匹配线圈对Goubau天线驻波比的影响,并仿真研究了传感器安装时手孔升高座对传感器驻波比的影响.进一步,在真型变压器上进行了局放监测实验.仿真和实测结果表明,设计的Goubau天线频带为400 ~1000MHz,并在该频段内有2个谐振点,方向图较好,阻抗匹配线圈能明显改善天线驻波比,手孔升高座对Goubau天线性能基本无影响,天线频域响应能够分辨不同的局部放电类型,适用于变压器局部放电特高频信号监测.%In recent years,ultra high frequency (UHF) method has become a widely used method for detecting partial discharge (PD) in transformers, and UHF sensor plays a crucial role in this method. A new type of UHF sensor-Goubau antenna is introduced and designed in this paper. The effect of impedance-matching coil on voltage standing wave ratio (VSWR) is studied and the influence of hand-hole ascending base on VSWR when the sensor is installed is studied in simulation. Moreover,the sensor was tested in real transformer. Both the simulation and test results show that the frequency band of Goubau antenna is 400 ~ 1 000 MHz,within which there are two resonance frequencies. The radiation pattern of the antenna is good. The impedance-matching coil can decrease the VSWR obviously. The hand-hole ascending base can hardly influence the antenna performance. The antenna frequency domain response can distinguish different types of PD sources. As a result,the Goubau antenna is suitable for detecting the UHF signals radiated from transformer PD.

  14. Analysis on Anti-tracking Jamming Performance of VHF/UHF Frequency-hopping Communication%超短波跳频通信抗跟踪式干扰性能分析

    Institute of Scientific and Technical Information of China (English)

    杨明; 陈静

    2014-01-01

    The tracking jamming is the most effective jamming mode of frequency-hopping communication. In order to analyze thoroughly the anti-tracking jamming performance of VHF/UHF frequency-hopping communication, the frequency-hopping communication principle and tracking jamming principle are analyzed. The anti-tracking jamming capability is mainly studied in different jamming tracking probability and time-resident conditions by simulations to obtain the corresponding bit error rate curve. The simulation results provide the theoretical reference for anti-tracking jamming test and application of VHF/UHF frequency-hopping com-munication.%当前对付跳频通信最有效的干扰方式为跟踪式干扰。为深入分析超短波跳频通信抗跟踪式干扰的性能,对跳频通信原理及跟踪式干扰原理进行了分析,采用仿真方法重点研究了不同干扰跟踪概率与驻留时间条件下的抗跟踪式干扰能力,并得到了相应的误码率曲线,仿真结果为超短波跳频通信抗跟踪式干扰测试与应用提供了理论参考。

  15. Study of the UHF Bowtie Antenna Used for Partial Discharge in HV Cable Accessories%检测高压电缆附件局部放电用超高频蝶形天线的研究

    Institute of Scientific and Technical Information of China (English)

    汪沨; 石倩; 刘烨; 姚亚利; 张广东

    2013-01-01

    针对电缆附件的结构及附件内部易发生绝缘故障导致局部放电的特点,设计了用于电缆附件局部放电信号检测的内置超高频超宽带蝶形天线传感器.仿真和实测表明,该蝶形天线的有效工作频带为350~585 MHz.模拟实验表明该天线传感器灵敏度高、性能优越,能在有效频率范围内检测到局部放电信号,可以用于电缆附件局部放电超高频信号的检测.%Considering cable accessories structure and the characteristic that insulation failure easily occurs in internal attachment resulting in partial discharge, this paper designed a built-in UHF and UWB bowtie antennas sensor to detect partial discharge signal for cable accessories. Simulation results show that the effective bandwidth of the antenna is 350~585 MHz. Measurement results also show that the antenna sensor has high sensitivity and superior performance, and can be applied to PD UHF signal detection of cable accessories.

  16. Study on Propagation Characteristics of UHF Signal via Hole of GIS Mental Flange and Development of External Radiating Antenna%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

    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

      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,通过加脊降低了矩形波导天线的下限截止频率,研制了双脊波导发射天线,在GIS设备上检验了该发射方法及装置的应用效果。研究表明, UHF电磁波以TE10波型为主模经过小孔传播,双脊波导天线的下限截止频率降到了300 MHz,通过它能够向GIS 内部发射300 MHz∼1.5 GHz的UHF标定信号。GIS体外式UHF标定信号注入方法可以为GIS局部放电UHF检测仪器现场灵敏度校验提供标定信号源。%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

  17. 超高频雷达海洋表面流的探测结果与分析%Results and analysis of surface current based on UHF radar

    Institute of Scientific and Technical Information of China (English)

    文必洋; 李艳; 侯义东; 杨静

    2016-01-01

    近岸海域地形、海流复杂,而超高频雷达系统具有较高距离分辨率、小发射功率的特点,波长介于高频电磁波和微波之间,能同时提取海浪毛细波与重力波信息,与波浪作用比较敏感,能实现近海海洋动力参数的精细测量.不同于高频雷达回波谱,超高频雷达回波中一阶峰、二阶峰展宽严重并混叠在一起,难以划分一阶峰区域,因此,文中系统设计采用数字波束形成进行流速方位提取.雷达反演的流速结果与浮标数据的相关系数为0.88,但是均方根误差很大.通过分析,得出海洋表面流速不仅受到潮汐效应、地球自转的影响,当地风速在很大程度上也会影响表面流速的结论.%Ultra high frequency(UHF)radar has the characteristics of high range resolution and low-power,which can extract information of both capillary wave and gravity wave with the wavelength be-tween high frequency and microwave.It is possible to obtain precise monitoring of the coastal ocean dy-namics parameters by UHF radar,though the offshore topography and ocean surface current are complex. UHF radar is different from HF radar,since the first-order peak and second-order spectrum are indistin-guishable in the sea echo spectrum.It is difficult to extract first-order peak,therefore,multiple signal classification algorithm (MUSIC)is unavailable and digital beam-forming(DBF)is used in extracting the radial velocity.After a month,the radar and buoy datais highly correlated with a coefficient of 0.88,how-ever,the root mean square error is large.The results show that the velocity of the ocean surface is influ-enced not only by the tidal effect and the rotationof the earth,but also by the local wind speed.

  18. Simulating the Attenuation Effects of Disk-Type Spacer in GIS on UHF Electromagnetic Wave%GIS盆式绝缘子对超高频电磁波衰减的仿真研究

    Institute of Scientific and Technical Information of China (English)

    王江; 钱勇; 叶海峰

    2012-01-01

    时域有限差分算法对GIS内局放激发超高频电磁波信号经盆式绝缘子的衰减特性进行仿真研究.首先研究了盆式绝缘子对超高频电磁波电场信号强度的衰减作用,指出绝缘子对在GIS腔体内传播的超高频电磁破电场强度衰减较小,对通过绝缘子泄漏到GIS腔体外的超高频电磁波电场强度衰减较大.然后研究了经绝缘子衰减后超高频电磁波电场信号增益的幅频特性,指出在GIS腔体内绝缘子对超高频电磁波的衰减集中在1000 MHz以上,而从绝缘子处泄漏到GIS腔体外的电磁波信号其衰减集中在1500 MHz以下和3000 MHz以上频率.%In this paper, Finite Difference Time Domain ( FDTD) method was used to simulate the attenuation effects of disk-type spacer in GIS on PD-induced UHF electromagnetic wave. Firstly, the attenuation effects of disk-type spacer on p-p value of PD-induced electromagnetic wave were evaluated. Simulating results show that p-p value of PD-induced electromagnetic wave is slightly attenuated when it transmits through the spacer inside the GIS chamber, while it is significantly attenuated when it leaks out of the chamber through the spacer. Secondly, the amplitude-frequency characteristics of E-filed gain when UHF electromagnetic wave transmits though the spacer was studied. Simulating results show that the attenuation frequency is mostly higher than 1 000 MHz when UHF signal transmits through the spacer inside the GIS chamber, while it is mostly in the span between 1 500 MHz and 3 000 MHz.

  19. UHF Radiowave Propagation through Forests

    Science.gov (United States)

    1990-07-01

    Periodic Dipole Transmitter polarization V, H, RCP Receiver polarization V, H, RCP , LCP Azimuthal range 360 degrees Height range 5-65 feet Transmitters...0,1,-.J2,1.02 2680 CLIP OFF 2690 FOR 1=1 TO 0 STEP -. 2 2700 MOVE .5,1 2710 LABEL USING Imagel;I 2720 Imagel:IMAGE MD.D S2730 NEXT I 2740 VIEWPORT 18*Xr...Ref title$[20,34] 2820 VIEWPORT O*Xri-15,4*Xr+15,26*Yr+10,91*Yr7+i0 2830 WINDOW 0,1,0,1 2840 CLIP OFF S2850 LDIR PI/2 2860 MOVE .5,.5 2870 LORG 5 2880

  20. UHF Radiowave Propagation through Forests

    Science.gov (United States)

    1984-05-01

    Probability Density Function 2-10 (Even-aged Stands) 2-4 Trunk Diameter Probability Density Function 2-11 (Uneven-aged Stands) 2-5 Stocking Guide for...Black walnut 6.1 12.6 18.8 Scarlet oak 5.0 11.0 17.9 Red oak 4.6 10.1 16.8 White ash 4.7 10.0 16.1 Black oak 4.8 10.1 15.9 Sugar maple 3.9 8.4 13.5 Beech...homogeneous forests. A potentially useful aid in characterizing forests for radiowave propagation prediction may be the forester’s " stocking guide

  1. 适用于直升机尾翼的UHF共形天线设计%Design UHF conformal antenna Suitable for a helicopter tail

    Institute of Scientific and Technical Information of China (English)

    李雪健; 李萍; 刘广斌

    2016-01-01

    ABSTRACT:In this paper,a suitable helicopter tail cylindrical conformal microstrip antenna is designed with both unit and binary array antenna respectively in embedded microstrip feeder mode.It turns out that cells in the 848MHz-860 MHz antenna VSWR were less than 1.5,at the frequency of 850 MHz,VSWR reached 1.073,the maximum gain of 6.9dB,S11 reach-30.4dB by using HFSS software unit and binry arrays antenna simulation. VSWR of Binary Arrays antenna were less than 1.5 in the frequency range 831 MHz -854 MHz,at the frequency of 850 MHz,VSWR reached 1.102,the maximum gain is 5.163dB,S11 reach -24.3dB,radiation substantially horizontal omnidirectional.The resonant frequency of the antenna covering the country's emergency rescue of the UHF band,and conformal with the helicopter tail,can be installed directly on the lower half arc helicopter wing,reducing the air resistance.%本文设计了一款适用于直升机尾翼的柱面共形微带天线,采用嵌入式微带馈线方式,分别设计了的单元和二元阵列天线。采用HFSS软件对单元和二元阵列天线进行了仿真,结果表明:单元天线在848MHz-860MHz频率范围内驻波比均低于1.5,在850 MHz处驻波达到1.073,最大增益为6.9dB,S11达到-30.4dB。二元阵列天线驻波比低于1.5的频率范围为831 MHz -854 MHz,在850 MHz处驻波达到1.102,最大增益为5.163dB,S11达到-24.3dB,辐射方向基本为水平全向。天线的谐振频率覆盖国内应急救援的UHF频段,天线与机体尾翼共形,可直接安装直升机尾翼的下半弧面上,减少了空气阻力。

  2. Design and Development of a New Electrically Small 3D UHF Spherical Antenna with 360° of Opening Angle in the Whole Space for RFID, WSN, and RSN Applications

    Directory of Open Access Journals (Sweden)

    Abdelhamid Bou-El-Harmel

    2016-01-01

    Full Text Available Several antenna designs have been made in order to obtain a novel electrically small 3D UHF spherical antenna (ka = 0.1916, which has a resonance frequency close to 915 MHz, produces a quasi-isotropic radiation with an opening angle equal to 360° in the whole space, and is used for RFID, WSN, and RSN applications. These antennas are based on different shapes and are wrapped on the Styrofoam sphere surface of dielectric constant close to air (ɛr=1.06. A T-match configuration is used to adapt the input impedance of antennas to a value of 50 Ω. The antennas form allows for placing the sensor electronics in its interior, to reconfigure it for numerous values of impedances and to operate it in other ISM bands by adjusting their geometric parameters.

  3. A Field Calibration Method for UHF Partial Discharge Detection Sensor Arrangement in GIS Based on Forward Propagation Coefficient%应用正向传输系数的GIS局部放电UHF传感器布置方式现场校核方法

    Institute of Scientific and Technical Information of China (English)

    舒胜文; 陈金祥; 陈彬; 叶兆平; 游浩; 黄海鲲

    2016-01-01

    为保证特高频(ultra-high-frequency,UHF)法在气体绝缘金属封闭开关设备(gas-insulated metal-enclosed switchgear, GIS)局部放电在线监测中应用的有效性,提出了一种基于微波网络正向传输系数(S21参数)的GIS局部放电UHF传感器布置方式现场校核方法。首先,在252 kV GIS真型试验平台上利用网络分析仪测试传感器间的S21参数,同时采用脉冲注入法间接计算传感器间的传递函数,结果表明:两者的频谱特性具有较好的一致性;在此基础上,研究了S21参数与不同缺陷类型局部放电频谱之间的相似度,结果表明:S21参数能有效反映UHF传感器对局部放电信号的接收特性。然后,在252 kV GIS真型试验平台上测试得到传感器间若要满足5 pC局部放电检测灵敏度,要求S21参数平均值≥−75 dB。最后,将提出的方法应用于1100 kV GIS局部放电UHF 传感器布置方式有效性的现场校核中,取得了良好的效果。研究成果可为 GIS 局部放电在线监测和带电巡检中UHF传感器的差异化布点提供参考。%In order to ensure effectiveness of ultra-high frequency (UHF) method in on-line monitoring of partial discharge for gas-insulated metal-enclosed switchgear (GIS), this paper proposes a field calibration method for UHF partial discharge detection sensors in GIS based on forward propagation coefficient in microwave network theory, often known asS21 parameter. Firstly, on a full- scale test platform based on 252 kV GIS equipment,S21 parameters between two UHF sensors were measured, and transfer functions between two UHF sensors were calculated indirectly with pulse injecting method. The results show that a good agreement between their frequency spectrum characteristics was obtained. On this basis, similarity betweenS21 parameter and frequency spectrum characteristics of partial discharge with different defect types was studied. The results show thatS21 parameter

  4. Dairy Cattle Breeding Management Applications Based on UHF RFID System%超高频RFID系统在奶牛养殖管理中的应用方案

    Institute of Scientific and Technical Information of China (English)

    梁坤; 张哲纯

    2013-01-01

    For the shortcomings of the current dairy farming management using manual , intermediate and low frequency RFID technology, a UHF RFID applications has been designed .This program uses ISO18000-6C protocol, and deploys stationary and handheld UHF reader .It can cover the whole field of dairy farming management businesses and it also effective solutes the problem of precise collecting each cow individual data and matching the dairy with the label .This program supplies a technical tool for the meticulous management of the dairy farming and it could improve the information level of pasture management .It also has a certain promotional value for other applications .%针对现行奶牛养殖管理采用人工及中低频RFID技术的缺点,设计了一种超高频 RFID 的应用方案。该方案采用ISO18000-6 C协议,将固定式和手持式超高频读写器配合部署,管理业务覆盖了奶牛养殖管理的全领域,有效解决了一牛一标签、精确采集每头奶牛个体数据的难题,为奶牛养殖的精细化管理提供了技术手段,有助于提升牧场的信息化管理水平,具备一定的推广价值。

  5. 特高频局部放电传感器的测点布置效能检验%Test on Layout Efficiency of UHF Partial Discharge Sensor

    Institute of Scientific and Technical Information of China (English)

    吴秋莉; 张炜; 梁俊斌; 邓雨荣

    2015-01-01

    This paper analyzes the characteristics of UHF sensor and the effects of GIS interior structure on it. The layout strategy of the test points of UHF sensor is studied and proposed. In the strategy, the monitoring sensor simulates partial discharge in GIS model and entity interval. The sample data is analyzed, based on which the effects of GIS interior structure and external disturbance on the monitoring effects are studied, and the monitoring results of in various sensor basin-type insulator flanges are compared. The strategy considers both the effective monitoring on partial discharge signals of the key devices and the economical allocation, and it helps to provide the basis for discharge source location.%分析特高频监测传感器特点及其受GIS内部不同结构的影响,针对具体外置传感器性能,研究并提出体现效能与成本平衡的传感器测点布置策略。该策略中,监测传感器在GIS模型及实体间隔内模拟局部放电,统计分析实验样本数据,讨论GIS内部结构及外部干扰对监测效果的影响,比较各类情况下传感器在盆式绝缘子法兰处的检测效果。该策略兼顾对关键设备局部放电信号的有效监测和配置经济原则,有利于为放电源定位提供依据。

  6. 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...

  7. UHF波段雷达面临基站干扰信号的极化特性测量与分析%Polarimetric Analysis of the Interference from Base Stations to UHF-band Radar

    Institute of Scientific and Technical Information of China (English)

    任博; 施龙飞; 王国玉

    2016-01-01

    移动通信基站的下行信号会影响UHF波段雷达的目标探测和跟踪,开展基站干扰环境的极化特性测量与分析,是利用极化处理手段对抗此类干扰的基础和依据。该文首先建立了UHF波段双极化雷达对基站信号接收模型,推导了极化比和极化度估计量的概率密度函数用以表征干扰环境极化统计特性;而后分别开展了对单个基站和多个基站的雷达外场接收测量试验,实验结果说明了确定性描述方法仅适用于表征极化度较高的单个基站信号,对多基站或极化度较低的情形则不再适用。通过实测数据与理论模型的拟合验证了该文给出的统计模型在描述两种场景下干扰信号统计特性上的正确性和适用性。%Radar detection and tracking performance in the UHF-band can be influenced by the downlink signals of communication base stations. The polarimetric properties of interference from base stations are measured and analyzed as a basis for suppressing this type of interference by a polarization processing method. In this study, we establish signal models from the base station for dual-polarization UHF-band radar. We express the Probability Density Functions (PDF) of the estimated polarization ratio and degree of polarization in a closed form and use them to describe the statistical properties of the interference environment. We developed polarimetric radar reception experiments for the signals from both Single-Base Stations (SBS) and Multi-Base Stations (MBS). Experimental results proved that deterministic polarized descriptions are appropriate only for signals from SBS but not from MBS or from stations with a low DoP (Degree of Polarization). However, the proposed statistical method can be used to describe both SBS and MBS cases, which we demonstrated by comparing the theoretical models with real measurement data.

  8. Research on and realization of contactless testing method of UHF RFID tags'resonance characteristics%U HF RFID 标签谐振特性非接触测试方法的研究与实现

    Institute of Scientific and Technical Information of China (English)

    李帅; 张雪凡; 任秀方; 孟春阳

    2015-01-01

    While UHF RFID tags being attached to the surface of various materials ,there will be great errors when we adopt the traditional method of cable connection test to get the tag's resonance characteristics .In this paper ,we formed a model of tag's power‐receiving ,analyzed the relationship between the energy obtained by tag chip and frequency ,and then proposed a contactless method to get the resonance characteristics of UHF RFID tags .This paper detailed the principle of using the relationship between frequency and distance to test the resonance characteristics ,illustrated the design concept of testing software , built and completely implemented the contactless hardware test platform . Measurement results demonstrated that the proposed method and platform can test the tag's resonance characteristics effectively . In practical applications , tags for different materials can be designed according to the resonance characteristics .%针对U H F RFID标签贴附在介质表面时,标签的谐振特性用接触式测量方法存在较大的误差问题,通过建立标签的接收功率模型,分析标签芯片获取到的能量与频率之间的关系,提出非接触式测试 U HF RFID谐振特性的方法。详细描述了利用频率和距离关系测试标签谐振特性的原理,说明了非接触式测试方法硬件测试平台的搭建方法和测试软件的编写思想,并完整地实现了该平台。实测实验证明,该测试方法和平台能有效地测试标签的谐振特性。在实际应用中,可以根据标签的谐振特性设计适合不同物体的标签。

  9. 变压器内置式超高频传感器安装位置选择仿真研究%Simulation Study on Selection of Install Location for UHF Sensor in Power Transformer

    Institute of Scientific and Technical Information of China (English)

    肖智刚; 董明; 邓彦国; 任明; 毕建刚; 阎春雨

    2014-01-01

    The detection sensitivity and effectiveness of UHF partial discharge(PD) are affected by the install location of sensors. To determine the influence of install location and provide some reasonable suggestions, taking a 220 kV transformer as example, we studied the propagation characteristics of the electromagnetic wave excited by different PD sources using finite difference time domain (FDTD) method. The rational install location of sensors were analyzed and discussed. The results show that the internal PD electromagnetic wave of transformers has complex propagation characteristics. The sensor installed at the front and back of the transformer can better detect the PD occurred between different windings and different phases. The simulation model can guide the selection of install location for UHF sensor in transformer.%在变压器局部放电超高频(UHF)检测中,局部放电检测灵敏度和有效性受到传感器安装位置的影响。为了确定传感器安装位置的影响程度和给出合理的安装建议,采用有限差分方法(FDTD),以一台220 kV变压器为例,对不同位置局部放电源激发的电磁波在变压器内部结构中的传播特性进行仿真研究,并对内置式传感器的合理安装位置进行分析和讨论。结果表明:由变压器内部局部放电产生的电磁波具有较为复杂的传播特性;安装于变压器箱体正面及背面的传感器能够更好的检测发生在调压、低压、中压及高压绕组之间以及相间的局部放电。通过仿真研究,证明了变压器仿真模型能够有效指导实际变压器UHF传感器安装位置的选择。

  10. 一种适用于UHF频段军事卫星通信的高效传输方案%An Effective Scheme to Enhance Information Transmitting Rate of the UHF MILSATCOM

    Institute of Scientific and Technical Information of China (English)

    张小辉; 陈建华; 张强龙; 杨剑飞; 胡应鹏

    2011-01-01

    特高频(UHF)频段由于其良好的通信性能,正愈发广泛地应用于军事卫星通信,尤其是卫星移动通信,然而由于该频段信道所受干扰和固有衰落的限制,UHF在卫星通信中的应用并非一帆风顺.如何提高系统通信容量及在干扰环境下的信道可用率是目前UHF频段军事卫星通信发展所面临的主要挑战.文章在分析UHF频段卫星通信特点的基础上,简要介绍了具有良好性能的低密度校验码(LDPC)码和连续相位调制(CPM)方式,并结合UHF频段的卫星信道特点,提出了一种新的发展对策--LDPC+CPM+FH的串行级联通信方案,最后对方案进行了建模和计算机仿真.

  11. 小波包分析在超高频检测GIS局部放电中的应用%The Application of Wavelet Packet Analysis in GIS PD UHF Detection

    Institute of Scientific and Technical Information of China (English)

    代红菊; 陈娟

    2012-01-01

    Ultra high frequency (UHF) is an effective method in detecting the partial discharge (PD) in gas insulation substation (GIS). The frequency characteristics of typical defect PD signal were studied through wavelet packet analysis (WPA). The "energy -frequency" mode was build through WPT. The results of the study showed that the UHF signal with different defects had different "energy - frequency" mode. The best detection frequency width could be selected by comparison of the "energy - frequency" characteristic value.%超高频法是检测GIS局部放电的有效方法,本文通过对GIS中典型缺陷超高频信号的小波包分析,对其频率分布特性进行了研究。利用小波包分解,构建了超高频信号的“能量一频率”模式特征。研究结果表明,不同缺陷的超高频信号具有不同的“能量一频率”特征,在现场进行检测时,应通过比较放电能量特征值,选择最佳频段进行检测。

  12. GIS局部放电绝缘子金属环孔特高频检测天线的研究%Study of the GIS UHF PD Detecting Sensor Installed on the Resin Sprue of Metal Ring of the Insulator

    Institute of Scientific and Technical Information of China (English)

    冯俊杰

    2015-01-01

    The external UHF sensor was installed on the surface of the insulator of GIS in most cases. However, a lot of insulators were encased by the metal rings currently, which prevented the conventional sensor from detecting. The only method is to detect the PD UHF signals leaking from the resin sprue of the metal ring. Due to the influence of the tiny dimension of the resin sprue, the attenuation characteristics of the UHF signals leaking from the resin sprue is unknown. In this paper, the attenuation characteristics of the UHF signals leaking from the resin sprue was studied through the experiment,then an external UHF sensor was designed, at last the sensitivity of the sensor was tested in the laboratory. According to the research, the polarization mode of UHF signals is linear polarization and the energy is mainly around the frequency band of 0.8~2 GHz. The dipole antenna was designed, and it belongs to the linear polarization antenna. The effective wide band of the sensor is 1~2 GHz, and the sensitivity of its detecting the PD signals leaking from the sprue is below 30 pC.%常规的GIS局部放电外置式特高频检测方法是将特高频传感器安装在GIS的盆式绝缘子表面,但目前大量GIS的绝缘子外侧安装了金属环,这使得常规的检测方法无法应用。此时特高频电磁波只有可能从金属环上的浇注孔传播出来,然而浇注孔尺寸很小,传播出来的信号的特性未知,从而无法设计检测天线。通过实验测试分析了电磁波通过浇注孔的传播特性,由此设计研制了振子天线,并在GIS平台上测试了其对于各种局放检测的灵敏度。研究表明:浇注孔传播出来的电磁波的极化方式为线极化,频带在0.8~2 GHz;振子天线传感器为线极化类型,其工作频带为1~2 GHz,检测浇注孔处局放信号的灵敏度达到了30 pC以下。

  13. 基于超高频的直流电场下油纸绝缘局部放电检测与特性研究%Partial Discharge Detection and Analysis of Oil-paper Insulation under DC Electric Filed Based on UHF Method

    Institute of Scientific and Technical Information of China (English)

    张倩; 刘宏亮; 吴建东; 尹毅

    2015-01-01

    为研究直流电场下的局部放电特性,开发了直流电场下局部放电的超高频信号测量系统,设计了针板、悬浮、沿面和气隙四种放电模型,通过对不同放电模型中局部放电产生的超高频信号进行测量和特性分析,研究了不同放电模型中超高频信号的频谱特性。结果表明:直流电场下不同放电模型中的局部放电可产生几百纳秒的超高频信号,其频谱分布中幅值较高的频段并不相同;在不同极性直流电场下,针板放电模型中超高频信号都存在300~500 MHz的超高频段,且负极性时还存在600~700 MHz的超高频段,除针板放电模型外的其他模型在不同极性直流电场作用下局部放电产生的超高频信号频谱较为相似;当外施直流电场升高时,局部放电产生的局部放电超高频信号的频谱幅值明显增大,但主要峰值的频率位置和频段并未发生明显变化,该特点可作为区分放电模式的有效依据。%To study the discharge characteristic under DC electric filed, we established an ultra high frequency (UHF) signal detection system of PD under DC electric filed, and designed four typical PD models including needle-plate, suspended particle, surface discharge, and cavity discharge model. The UHF signals generated by PD in different discharge models were tested, and their spectrum characteris-tics were studied. The results show that the PD in different discharge models under DC electric filed can generate UHF signals lasting for hundreds of ns, and their frequency bandwidths with high spectrum am-plitude were different. The frequency bandwidth with high spectrum amplitude of UHF signals in needle-plate discharge model under different polarities of DC electric field is between 300 MHz and 500 MHz, and the frequency bandwidth with high spectrum amplitude under negative DC is between 600 MHz and 700 MHz. The frequency spectra of UHF signals in other discahrge

  14. 一种基于超高频RFID技术的血液管理智能门系统的研制%Development of UHF RFID Technology-based Intelligent Door System for Blood Management

    Institute of Scientific and Technical Information of China (English)

    王全立; 宋海婷; 张鹏; 徐丽娟; 邵春燕; 陈民才; 陆颖; 刘佳; 冯学胜; 卓海龙

    2012-01-01

    Objective To develop a kind of intelligent door system for blood management to realize real-time monitoring and quick bank-in & bank-out of massive blood. Methods UHF RFID technology was used to develop the intelligent door system composed of the reader, starter, information processing module, information display module and voice broadcast module. The speeds, accuracies and integrity of bank-in & bank-out of the blood by the scanning spear, handset and the door system were compared. Results The average bank-in time for 50 bags of blood by the scanning spear, handset and intelligent door was 225 s, 65 s and 59 s respectively, and the average bank-out time by the handset and intelligent door was 15 s and 6 s respectively, with P less than 0.01. When compared with the intelligent door, the scanning spear and handset lacked the information on the personnel and refrigerator despite the correct number of bank-in & bank-out blood. Conclusion The UHF RFID technology-based intelligent door system for blood management can enhance the efficiency and safety of the blood inventory management for its high speed and accurate information.%目的:研制一种血液管理智能门系统,实现实时监控和快速批量出入库的目的.方法:应用超高频RFID技术,研制包括读取器、启动装置、信息处理模块、信息显示模块和语音播报模块组成的智能门系统,比较扫描枪、手持机和智能门三者血液出入库的速度、准确性和完整性.结果:50袋血液平均入库时间:扫描枪225 s,手持机65 s,智能门59 s(P<0.01);平均出库时间:手持机15s,智能门6 s(P<0.01).与智能门比较,虽然扫描枪和手持机的出入库数量和数据准确,但内容不完整,缺少入库人、血液所在冰箱位置的信息.结论:智能门扫描出入库的速度最快,出库数量和数据准确,内容完整,提高了血液库存管理的效率和安全性.

  15. 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

    OpenAIRE

    María del Pilar Celemín; Willer Ferney Montes Granada

    2007-01-01

    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....

  16. The Application and Implementation Effect Evaluation of UHF RFID Technology in Libraries%超高频RFID技术在高校图书馆的应用及效果评价——以河北联合大学图书馆为例

    Institute of Scientific and Technical Information of China (English)

    吴卫华; 王艳红; 李亚君

    2013-01-01

    阐述了RFID技术在图书馆中的应用现状以及河北联合大学图书馆进行UHF RFID应用的过程,并采用层次分析法,从读者满意度的角度选择评价指标,对RFID的实施效果进行评价,为拟用或正在使用RFID系统的图书馆提供一些经验和启示.

  17. Dual Beam System (SEM/FIB) Equipment for the Kleberg Advanced Microscopy Center

    Science.gov (United States)

    2015-06-05

    transmission electron microscopy Authors:Arturo Ponce Organizers: Sociedad de Superficies y Vacio Place: Ensenada, Mexico Date: Oct. 2014 2. II...Title: In situ physical measurements in transmission electron microscopy Authors: Arturo Ponce Organiz ers: Sociedad de Superficies y Vacio Place

  18. Fast three-dimensional nanoscale metrology in dual-beam FIB-SEM instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, Luca, E-mail: luca.repetto@unige.it [Nanomed Labs - Centro Biotecnologie Avanzate and Physics Department, Universita di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Buzio, Renato; Denurchis, Carlo; Firpo, Giuseppe; Piano, Emanuele; Valbusa, Ugo [Nanomed Labs - Centro Biotecnologie Avanzate and Physics Department, Universita di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2009-10-15

    A quantitative surface reconstruction technique has been developed for the geometric characterization of three-dimensional structures by using a combined focused ion beam-scanning electron microscopy (FIB-SEM) instrument. A regular pattern of lines is milled at normal incidence on the sample to be characterized and an image is acquired at a large tilt angle. By analyzing the pattern under the tilted view, a quantitative estimation of surface heights is obtained. The technique has been applied to a test sample and nanoscale resolution has been achieved. The reported results are validated by a comparison with atomic force microscopy measurements.

  19. Fast three-dimensional nanoscale metrology in dual-beam FIB-SEM instrumentation.

    Science.gov (United States)

    Repetto, Luca; Buzio, Renato; Denurchis, Carlo; Firpo, Giuseppe; Piano, Emanuele; Valbusa, Ugo

    2009-10-01

    A quantitative surface reconstruction technique has been developed for the geometric characterization of three-dimensional structures by using a combined focused ion beam-scanning electron microscopy (FIB-SEM) instrument. A regular pattern of lines is milled at normal incidence on the sample to be characterized and an image is acquired at a large tilt angle. By analyzing the pattern under the tilted view, a quantitative estimation of surface heights is obtained. The technique has been applied to a test sample and nanoscale resolution has been achieved. The reported results are validated by a comparison with atomic force microscopy measurements.

  20. Dual-beam irradiation of {alpha}-iron: Heterogeneous bubble formation on dislocation loops

    Energy Technology Data Exchange (ETDEWEB)

    Brimbal, Daniel, E-mail: Daniel.brimbal@cea.fr [Laboratoire d' Analyse Microstructurale des Materiaux (LA2M), CEA/Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif-sur-Yvette Cedex (France); Decamps, Brigitte, E-mail: Brigitte.decamps@csnsm.in2p3.fr [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masses (CSNSM/IN2P3/CNRS), Orsay University, Bat. 108, 91405 Orsay Campus (France); Barbu, Alain, E-mail: Alain.barbu@cea.fr [Service de Recherches de Metallurgie Physique (SRMP), CEA/Saclay, DEN/DMN/SRMP, 91191 Gif-sur-Yvette Cedex (France); Meslin, Estelle, E-mail: Estelle.Meslin@cea.fr [Service de Recherches de Metallurgie Physique (SRMP), CEA/Saclay, DEN/DMN/SRMP, 91191 Gif-sur-Yvette Cedex (France); Henry, Jean, E-mail: Jean.henry@cea.fr [Laboratoire d' Analyse Microstructurale des Materiaux (LA2M), CEA/Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-15

    Highlights: > We have irradiated {alpha}-iron in situ with Fe{sup +} and He{sup +} ions at 500 deg. C. > Dislocation loops and helium bubbles are present at 1 dpa/540 appm He. > The helium bubbles are located heterogeneously on the dislocation loops. - Abstract: In order to understand the evolution of materials under irradiation conditions similar to those in future fusion reactors, we have irradiated high purity iron in situ in a transmission electron microscope with 1 MeV Fe{sup +} ions while simultaneously implanting 15 keV He{sup +} ions, at 500 deg. C. Once {approx}1 dpa/500 appm He were reached, helium bubbles and large dislocation loops were observed. The study reveals that helium bubbles nucleated heterogeneously: a majority of them were observed inside the large dislocation loops.

  1. Correlated two-photon interference in a dual-beam Michelson interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kwiat, P.G.; Vareka, W.A. (Department of Physics, University of California, Berkeley, California 94720 (USA)); Hong, C.K.; Nathel, H. (University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (USA)); Chiao, R.Y. (Department of Physics, University of California, Berkeley, California 94720 (USA))

    1990-03-01

    We report on an interference effect arising from a two-photon entangled state produced in a potassium dihydrogen phosphate (KDP) crystal pumped by an ultraviolet argon-ion laser. Two conjugate beams of signal and idler photons were injected in a parallel configuration into a single Michelson interferometer, and detected separately by two photomultipliers, while the difference in its arm lengths was slowly scanned. The coincidence rate exhibited fringes with a visibility of nearly 50%, and a period given by half the ultraviolet (not the signal or idler) wavelength, while the singles rate exhibited no fringes.

  2. A Dual-beam Implanter for Research of Material Irradiation Effect

    Institute of Scientific and Technical Information of China (English)

    TANG; Bing; CUI; Bao-qun; MA; Ying-jun; MA; Rui-gang; CHEN; Li-hua; HUANG; Qing-hua; MA; Xie

    2015-01-01

    With the development of reactor technology,the researches on the effect of material irradiation are becoming more and more interesting and expanding.To understand and model the aging caused by atomic displacements,helium and hydrogen production,material scientists and reactor

  3. Radiation induced microstructures in ODS 316 austenitic steel under dual-beam ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, He Ken [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L3N6, Ontario (Canada); Yao, Zhongwen, E-mail: yaoz@me.queensu.ca [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L3N6, Ontario (Canada); Zhou, Zhangjian; Wang, Man [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Kaitasov, Odile [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay 91405 (France); Daymond, Mark R. [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L3N6, Ontario (Canada)

    2014-12-15

    An ODS 316 austenitic steel was fabricated and irradiated using dual ion beams (1 MeV Kr{sup +} and 15 keV He{sup +}) with in-situ transmission electron microscope (TEM) observation. Cavities formed at a low dose in samples irradiated with simultaneous helium injection. It was found that Y–Ti–O particles acted as strong traps for cavity formation at low doses. Helium exhibited a significant effect on cavity development. Cavities were also preferentially nucleated along grain boundaries, phase boundaries and twin boundaries. Irradiation induced lattice defects mainly consisted of small 1/2〈1 1 0〉 perfect loops and 1/3〈1 1 1〉 Frank loops. An increment of helium injection rate also greatly enhanced the Frank loop growth. Small (<10 nm) Y–Ti–O particles were found to be unstable after irradiation to high doses. M{sub 23}C{sub 6} precipitates were observed after irradiation and helium might play a major role in their formation.

  4. Hybrid laser-beam-shaping system for rotatable dual beams with long depth of focus

    Science.gov (United States)

    Chou, Fu-Lung; Chen, Cheng-Huan; Lin, Yu-Chung; Lin, Mao-Chi

    2016-08-01

    A laser processing system consisting of two diffractive elements and one refractive element is proposed enabling a Gaussian laser beam to be transformed into two beams with a depth of focus of up to 150 µm and focal spot smaller than 5 µm. For specific laser processing, the two beams are rotatable when the beam-splitting diffractive element is rotated. The overall system is versatile for laser cutting and drilling.

  5. On-site analysis of modified surface using dual beam system

    Energy Technology Data Exchange (ETDEWEB)

    Naramoto, Hiroshi; Aoki, Yasushi; Yamamoto, Shunya; Goppelt-Langer, P.; Gan Mingle; Zeng Jianer; Takeshita, Hidefumi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    Recent results obtained using a dual ion beam system at JAERI/Takasaki are reported. In this system, both of ion implantation and ion beam analysis can be made alternatively or simultaneously at low temperatures. In sapphire implanted with {sup 51}V{sup +} ions, the amorphization process is analyzed referring to the <0001> aligned spectra taken at different temperatures. The discussion is made on the defect profiles different from the simple accumulation of standard Gaussian form. The depth showing the maximum damage at the initial stage of implantation is quite shallow compared with those reported before. The thermal annealing behaviors of lattice damage and the implanted V atoms are also different between the samples implanted at low and room temperatures. In the former one fine particles of vanadium oxide are formed coherently with the easy recovery in high dose sample but in the latter the mixed oxide alloy is formed. (author)

  6. Speckle dynamics for dual-beam optical illumination of a rotating structure

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Yura, Harold; Hanson, Steen Grüner

    2009-01-01

    An out-of-plane rotating object is illuminated with two spatially separated coherent beams, giving rise to fully developed speckles, which will translate and gradually decorrelate in the observation plane, located in the far field. The speckle pattern is a compound structure, consisting of random...... Fourier transform system. It is shown that the compound speckle structures move as two individual structures with the same decorrelation length. The velocity of the random speckles is a combination of angular and peripheral velocity, where the peripheral velocity is inversely proportional to the radius...

  7. A Dual-Beam Irradiation Facility for a Novel Hybrid Cancer Therapy

    CERN Document Server

    Sabchevski, Svilen; Ishiyama, Shintaro; Miyoshi, Norio; Tatsukawa, Toshiaki

    2012-01-01

    In this paper we present the main ideas and discuss both the feasibility and the conceptual design of a novel hybrid technique and equipment for an experimental cancer therapy based on the simultaneous and/or sequential application of two beams, namely a beam of neutrons and a CW (continuous wave) or intermittent sub-terahertz wave beam produced by a gyrotron for treatment of cancerous tumors. The main simulation tools for the development of the computer aided design (CAD) of the prospective experimental facility for clinical trials and study of such new medical technology are briefly reviewed. Some tasks for a further continuation of this feasibility analysis are formulated as well.

  8. Speckle dynamics for dual-beam optical illumination of a rotating structure

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Yura, Harold; Hanson, Steen Grüner

    2009-01-01

    An out-of-plane rotating object is illuminated with two spatially separated coherent beams, giving rise to fully developed speckles, which will translate and gradually decorrelate in the observation plane, located in the far field. The speckle pattern is a compound structure, consisting of random...... speckles modulated by a smaller and repetitive structure. Generally, these two components of the compound speckle structure will move as rigid structures with individual velocities determined by the characteristics of the two illuminating beams. Closed-form analytical expressions are found for the space......- and time-lagged covariance of irradiance and the corresponding power spectrum for the two spatially separated illuminating beams. The present analysis is valid for propagation through an arbitrary ABCD system, though the focus for the experimental evaluation is far-field observations using an optical...

  9. Integration of Correlative Raman microscopy in a dual beam FIB-SEM J. of Raman Spectroscopy

    NARCIS (Netherlands)

    Timmermans, Frank Jan; Liszka, B.; Lenferink, Aufrid T.M.; van Wolferen, Hendricus A.G.M.; Otto, Cornelis

    2016-01-01

    We present an integrated confocal Raman microscope in a focused ion beam scanning electron microscope (FIB SEM). The integrated system enables correlative Raman and electron microscopic analysis combined with focused ion beam sample modification on the same sample location. This provides new

  10. Research on Partial Discharge Detection and Localization of Dry-Type Transformer Based on UHF and Ultrasonic Wave%基于超高频和超声波的干式变压器局部放电检测与定位的研究

    Institute of Scientific and Technical Information of China (English)

    王永强; 张涛; 王慧君

    2013-01-01

    The demand for the safety and effective of the dry-type transformer is high in the process of operation, therefore the partial discharge detection of dry-type transformer is particularly important. This paper mainly analyzes the principle and test methods of UHF and ultrasonic wave based partial discharge detection methods for dry-type transformer. A partial discharge detection system is built based on the combination of UHF and ultrasonic wave methods, which can locate the partial discharge source. This system provides reference for partial discharge detection.%对于干式变压器在运行过程中的安全有效性要求越来越高,因此对其进行局部放电检测尤为重要。本文主要分析了检测干式变压器局部放电的超高频方法与超声波方法的原理及检测方法,并设计了一套超高频与超声波相联合的局部放电检测系统,通过该系统,对局部放电源进行定位,对干式变压器的局部放电检测提供了参考。

  11. The Maximum Energy of Wavelet Decomposition Approximation -Related Adaptive Wavelet De-Nosing for Partial Discharge UHF Pulse in GIS%基于小波分解尺度系数能量最大原则的GIS局部放电超高频信号自适应小波去噪

    Institute of Scientific and Technical Information of China (English)

    李化; 杨新春; 李剑; 陈娇; 程昌奎

    2012-01-01

    抑制干扰是GIS局部放电在线监测的关键技术之一。尽管局部放电超高频检测方法能够有效避开低频干扰,但来自测量系统的白噪声仍然为准确测量局部放电带来困难。为有效抑制白噪声,提高局部放电超高频法的测量精度,本文提出一种用于GIS局部放电超高频信号的自适应小波分解去噪算法,该算法基于每层小波分解尺度系数能量最大的原则,逐层自适应选取最优的小波进行分解,并结合Donoho提出的软阈值法进行去噪。对人工绝缘缺陷产生的四种GIS超高频信号的去噪结果证明了该算法较其他小波算法能更好地去除白噪声且去噪后信号波形畸变较小,具有很好的应用前景。%Interference suppression was one of the key technologies in on-line partial discharge(PD) monitoring of gas insulated switchgear(GIS). Although ultra-high-frequency (UHF) is qualified to avoid low-frequency noises, the system white noise from the high voltage transmission line still make it difficult to accurately measure the level of PD. For active inhibition of the white noise interference and improving the precision of the UHF detection methods, this paper presents a adaptive de-noising scheme, which is suitable for de-noising UHF signal detected by the UHF detection system of PD in GIS. The method utilizes various basic wavelet to decompose a signal, and calculate and compare the signal energies caused by decomposition using different wavelets in each scale. The basic wavelet corresponding to the maximum signal energy is considered as the optimum wavelet in the current scale, thus the optimum wavelets family of all the scales is obtained, and the soft threshold function presented by Donoho is used to de-nosing. The result of de-noising a UHF signal generated by an artificial insulation defect convinces that the adaptive wavelet de-noising method is more effective to suppress the white noise mixed in

  12. A Broadband Antenna for the Application to Multi-Standard UHF RFID Tag%适用于多标准的超高频宽带RFID标签天线

    Institute of Scientific and Technical Information of China (English)

    褚庆昕; 曾锐华

    2011-01-01

    Proposed in this paper is a broadband antenna for the application to multi-standard UHF RFID (Radio Frequency Identification) tag, which is composed of a dipole-like radiating body and a inductively-coupled feeding loop. The radiating body consists of two modified meandered dipole antennas different in length so as to form two resonance points only slightly different in frequency. Thus, the antenna impedance, especially its imaginary part,keeps steady in the frequency range of 840 to 956 MHz, and good conjugate impedance matching to the RFID tag chip is obtained. The bandwidth of the antenna varies from 816 to 988 MHz, which is wide enough to cover the global ultrahigh-frequency RFID frequency range, so that the tags with the proposed antenna can be used globally without replicate design and the cost is greatly reduced. Finally, an antenna prototype is fabricated based on the simulation model, with good accordance being found between the simulated and the measured results.%提出了一种宽带标签天线,该天线适用于多标准超高频射频识别(RFID)系统,由一个类偶极子辐射体和一个电感耦合馈电环构成.类偶极子辐射体包含两个变型弯折偶极子天线.这两个变型弯折偶极子天线的长度有差别,可以形成两个相近的谐振点,使得天线的阻抗(特别是虚部)在840~956MHz的范围内保持平稳,以获得与芯片阻抗在较宽频段内的良好的共轭阻抗匹配,从而使天线获得一个非常宽的带宽(816~988 MHz),该带宽足以覆盖全球超高频RFID频率范围,使得标签可以全球通用,大大减少了重复设计工作量,有效降低了成本.最后基于仿真模型,加工了一个天线实物,实物测量结果与仿真结果吻合良好.

  13. Frequency Measurement of FDR Based on Soil Dielectric Spectrum in LF-UHF%基于土壤LF-UHF频段介电特性的FDR测量频率研究

    Institute of Scientific and Technical Information of China (English)

    许景辉; 马孝义; Sally D Logsdon; Robert Horton

    2013-01-01

    土壤介电特性是影响FDR传感器测量土壤含水量精度和适应性的重要物理参数.为了确定28 mm长、10 mm间距的7探针FDR传感器理想频率,通过矢量网络分析仪对4种不同土壤的LF-UHF频段(1 MHz ~3 GHz)散射参数进行了测量,通过Logsdon和Laird模型变换,使用Matlab进行了4种土壤表观介电常数的计算和绘制.通过土壤介电频谱分析,研究了土壤极化机理,分析了土壤介电特性与频率的关系,确定了FDR传感器的工作频段为44 ~ 398 MHz,考虑到温度对极化的影响,其最佳工作频段为62 ~ 110 MHz,其中75 MHz是其工作的最佳频率.此频率下土壤介电值仅对土壤含水量敏感,是消除温度等因素对FDR传感器影响的理想频率.%Soil dielectric property is an important physical parameter affecting the measuring accuracy and adaptation of moisture content by using FDR sensor.In order to obtain the best frequency of 7-probes FDR with length of 28 mm and needle-to-needle spacing of 10 mm,scattering parameters of LF-UHF wave bands (1 MHz ~ 3 GHz) in four kinds of soil were measured by using VNA.Though transformation based on Logsdon model and Laird model,four soil apparent dielectric permittivities were calculated and figured in Matlab.The mechanism of soil polarization was analyzed by soil dielectric spectrun analysis.The relationship between soil dielectric property and frequency was discussed.The working frequency of 44 ~ 398 MHz for FDR sensor was confirmed.Taking temperature into consideration,the ideal working frequency band was 62 ~ 110 MHz in which 75 MHz was the best.The soil dielectric value was only sensitive to soil moisture content under the best frequency.It was the ideal frequency for eliminating the effect of temperature and other factors on FDR sensor.

  14. TEV和UHF在10kV开关柜带电检测中的应用%Application of TEV and UHF in PD Detection for the Live 10 kV Switchgear

    Institute of Scientific and Technical Information of China (English)

    曾雄杰; 江健武; 侯俊

    2012-01-01

    10、35 kV金属封闭式开关柜在变电站广泛使用,其运行安全直接影响整个变电站的供电可靠性.因此,对开关柜运行状态的监测及对故障的预判和合理检修是保证开关设备安全可靠运行的关键.笔者介绍了10 kV开关柜局部放电带电测试的TEV和UHF原理,并且成功检测出了深圳某变电站10 kV 2BM、3BM过渡CT柜532BCT柜存在局部放电信号,同时通过对532BCT柜的停电检查,发现532BCT柜中的隔离开关A相静触头是产生局部放电信号的源头所在,从而验证了采用TEV和UHF这两种原理相结合的方式检测10 kV开关柜故障的有效性,为较早地发现10 kV开关柜中的设备缺陷提供了有效检测方法和依据.%Metal-enclosed switchgear rated voltage 10, 35 kV in substations are widely used, which operating security directly affects the supply reliability of substation. Therefore, switchgear operating state monitoring, fault prejudging and reasonable overhaul are the key to guarantee safe and reliable operation of switchgear. The paper explains the principle of TEV and UHF in detecting 10 kV switchgear PD signal respectively. And it also shows the successful application of these two methods in detecting and discovering PD signal on 10 kV 532BCT switchgear of one station. Open and check the equipment, the PD signal has been found on 532BCT disconnecting switch of phase A. This example proves that the combination of both methods is effective in detecting switchgear defect and provides effective methods and basis for finding defects in 10 kV switchgear.

  15. One Kilowatt UHF Solid State Power Amplifier.

    Science.gov (United States)

    1982-02-01

    Intermodulation Products Measurement 30 5. Thermal Test 43 IV SUMMARY AND CONCLUSIONS 51 APPENDIX -PARATUNE FILTER SPECIFIC INTERFACE DETAILS 53 V AFWAL-TR-81 -11...Distribution (Nominal Sea Level 71-C) 49 35 1 KIW Thermal Test 50 A-1 1 KW AN/ARC-31/AN/ARC 171 Interface 55 vii AFWAL-TR-81-1152 LIST OF TABLES TABLE PAGE 1...and thus it is reduced by approximately only 25 db, and more intermod products are showing up. 5. THERMAL TEST A thermal test was conducted on the AN

  16. 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

  17. 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.

  18. 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

    2016-07-14

    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.

  19. Development of a microstrip UHF conformal antenna

    Science.gov (United States)

    Shields, M. W.; Cassell, R. B.

    1977-01-01

    Low profile, engineering model EMU antennas were constructed. Final data for these antennas meet most of the electrical requirements in a 6 in. x 18 in. x 1.4 in. package which weighs under 2.0 lbs. Coverage data calculated at the design frequencies very nearly meets the design goal of providing a gain greater than or equal to -10 dBi over 80% of a sphere. Recommendations are made for future work directed toward producing an efficient quality design capable of operating in a space environment.

  20. Gas and Stars in an H I-Selected Galaxy Sample

    Science.gov (United States)

    Rosenberg, Jessica L.; Schneider, Stephen E.; Posson-Brown, Jennifer

    2005-03-01

    We present the results of a J-band study of the H I-selected Arecibo Dual-Beam Survey and Arecibo Slice Survey galaxy samples using Two Micron All Sky Survey data. We find that these galaxies span a wide range of stellar and gas properties. However, despite the diversity within the samples, we find a very tight correlation between luminosity and size in the J band, similar to that found in a previous paper by Rosenberg & Schneider between the H I mass and size. We also find that the correlation between the baryonic mass and the J-band diameter is even tighter than that between the baryonic mass and the rotational velocity.

  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. An Experimental Investigation of Wave Measurements Using a Dual-Beam Interferometer: Gulf Stream as a Surface Wave Guide

    Science.gov (United States)

    2006-09-13

    including suggestions for reducing the burden, to the Department of Defense, Executive Services and Communications Directorate 10704-0188...radar wavelength, IV’, the platforml speed. and image pixels is between 500 and 81’. Figure 4 shows B, the efective baseline, which is one-half of the...sequential filtering is empirically set at 72Ax, line (Huang, personal communication ). 36A1, 24Ax, 12A1 and 61v. where Ax = 6 m, therefore, the 12 of 15

  3. A dual-beam dual-camera method for a battery-powered underwater miniature PIV (UWMPIV) system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Binbin; Liao, Qian [University of Wisconsin-Milwaukee, Department of Civil Engineering and Mechanics, Milwaukee, WI (United States); Bootsma, Harvey A. [University of Wisconsin-Milwaukee, School of Freshwater Sciences, Milwaukee, WI (United States); Wang, Pei-Fang [Space and Naval Warfare Systems Center, Advanced Systems and Applied Sciences, Envrionmental Sciences, San Diego, CA (United States)

    2012-06-15

    A battery-powered in situ Underwater Miniature PIV (UWMPIV) has been developed and deployed for field studies. Instead of generating high-energy laser pulses as in a conventional PIV system, the UWMPIV employs a low-power Continuous Wave (CW) laser (class IIIb) and an oscillating mirror (galvanometer) to generate laser sheets. In a previous version of the UWMPIV, the time between exposures of a pair of particle images, {delta}t, could not be reduced without loss of illumination strength. This limitation makes it unsuitable for high-speed flows. In this paper, we present a technique to solve this problem by adopting two CW lasers with different wavelength and two CCD cameras in a second-generation UWMPIV system. Several issues including optical alignment, non-uniform distribution of {delta}t due to the varying speed of the scanning beam and local flow velocities are discussed. The timing issue is solved through a simple calibration procedure that involves the reconstruction of maps of laser beam arrival time. Comparison of the performance between the new method and a conventional PIV system is presented. Measurements were performed in a laboratory open-channel flume. Excellent agreement was found between the new method and the standard PIV measurement in terms of the extracted vertical profiles of mean velocity, RMS fluctuation, Reynolds stress and dissipation rate of turbulent kinetic energy. (orig.)

  4. 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

  5. Temperature increase in the fetus exposed to UHF RFID readers.

    Science.gov (United States)

    Fiocchi, Serena; Parazzini, Marta; Liorni, Ilaria; Samaras, Theodoros; Ravazzani, Paolo

    2014-07-01

    Exposure to electromagnetic fields (EMFs) has prominently increased during the last decades due to the rapid development of new technologies. Among the various devices emitting EMFs, those based on Radio-frequency identification (RFID) technologies are used in all aspects of everyday life, and expose people unselectively. This scenario could pose a potential risk for some groups of the general population, such as pregnant women, who are expected to be possibly more sensitive to the thermal effects produced by EMF exposure. This is the first paper that addresses the estimation of temperature rise in two pregnant women models exposed to ultrahigh frequency RFID by computational techniques. Results show that the maximum temperature increase of the fetus and of the pregnancy-related tissues is relatively high (even about 0.7 °C), not too far from the known threshold of biological effects. However, this increase is confined to a small volume in the tissues.

  6. 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.

  7. Qualification of UHF Antenna for Extreme Martian Thermal Environments

    Science.gov (United States)

    Ramesham, Rajeshuni; Amaro, Luis R.; Brown, Paula R.; Usiskin, Robert

    2013-01-01

    The purpose of this development was to validate the use of the external Rover Ultra High Frequency (RUHF) antenna for space under extreme thermal environments to be encountered during the surface operations of the Mars Science Laboratory (MSL) mission. The antenna must survive all ground operations plus the nominal 670 Martian sol mission that includes summer and winter seasons of the Mars thermal environment.The qualification effort was to verify that the RUHF antenna design and its bonding and packaging processes are adequate to survive the harsh environmental conditions. The RUHF is a quadrifilar helix antenna mounted on the MSL Curiosity rover deck. The main components of the RUHF antenna are the helix structure, feed cables, and hybrid coupler, and the high-power termination load. In the case of MSL rover externally mounted hardware, not only are the expected thermal cycle depths severe, but there are temperature offsets between the Mars summer and winter seasons. The total number of temperature cycles needed to be split into two regimes of summer cycles and winter cycles. The qualification test was designed to demonstrate a survival life of three times more than all expected ground testing, plus a nominal 670 Martian sol missions. Baseline RF tests and a visual inspection were performed prior to the start of the qualification test. Functional RF tests were performed intermittently during chamber breaks over the course of the qualification test. For the RF return loss measurements, the antenna was tested in a controlled environment outside the thermal chamber with a vector network analyzer that was calibrated over the antenna s operational frequency range. A total of 2,010 thermal cycles were performed. Visual inspection showed a dulling of the solder material. This change will not affect the performance of the antenna. No other changes were observed. RF tests were performed on the RUHF helix antenna, hybrid, and load after the 2,010 qualification cycles test. The RF performance of the RUHF antenna, hybrid, and load were almost identical before and after the complete test. Therefore, the developed design of RUHF is qualified for a long-duration MSL mission. The RUHF antenna has not been used for long-duration missions such as MSL in the past. The state-of-the-art technology of the RUHF antenna is used to develop the antennas for MSL mission survivability. This developmental test data provides the confidence in using this RUHF antenna for future NASA missions to Mars.

  8. 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.

  9. 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

    2015-10-22

    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.

  10. 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.

  11. UHF Microstrip Antenna Array for Synthetic- Aperture Radar

    Science.gov (United States)

    Thomas, Robert F.; Huang, John

    2003-01-01

    An ultra-high-frequency microstrippatch antenna has been built for use in airborne synthetic-aperture radar (SAR). The antenna design satisfies requirements specific to the GeoSAR program, which is dedicated to the development of a terrain-mapping SAR system that can provide information on geology, seismicity, vegetation, and other terrain-related topics. One of the requirements is for ultra-wide-band performance: the antenna must be capable of operating with dual linear polarization in the frequency range of 350 plus or minus 80 MHz, with a peak gain of 10 dB at the middle frequency of 350 MHz and a gain of at least 8 dB at the upper and lower ends (270 and 430 MHz) of the band. Another requirement is compactness: the antenna must fit in the wingtip pod of a Gulfstream II airplane. The antenna includes a linear array of microstrip-patch radiating elements supported over square cavities. Each patch is square (except for small corner cuts) and has a small square hole at its center.

  12. UHF Antenna Design for AFIT Random Noise Radar

    Science.gov (United States)

    2012-03-01

    printed circuit board antenna construction methods. The antipodal chopped Vivaldi dipole antenna, built with a milling machine, v achieved a wider... circuit board antenna (right) ............................................................. 2 Figure 2 – CST Simulated S11 parameter of the LPA...79 xii Figure 60 – Surface current (10.6 GHz) of antipodal CVD antenna from Yang et al [1] (4.5cm x 4.6cm, 50Ω microstrip feed

  13. UHF (Ultra-High-Frequency) Propagation in Vegetative Media.

    Science.gov (United States)

    1980-04-01

    Electronic Products (February 1963). In this communication, a simple extension of the theory developed by Stratton and Wheeler was applied to HF and VHF...the intensity for waves of arbitrary order (I/SUP NI) are written down as Feynman con- tinual integrals (in operator form). Expressions for the higher...Identifiers: Electromagnetic waves; random medium; finite inhomo- geneity correlation range; parabolic equation; statistical moments; Feynman continual

  14. Concept Study for UHF T/R Modules

    Science.gov (United States)

    1990-02-01

    corresponding devices. At present, Henry F. Gray at NRL is a good resource on this technology. o Optimize the level of integration of the components in the...McDonnell Larry Corey Phil Metzen Jim Degenford M. Murphy Dave Dewall Rob Pauley Richard Dougherty Ken Petrosky John Englund Kevin Romer George Ewell Dave...Chris Vale Dick Harden Gary Valentine Mike Harris Jim Van Damme Lloyd Hazel Daryl Vaughan Roy Hejhall Ray Waddoups Robert Henry Larry Whicker Dave

  15. Near-Field Loop Antenna for the UHF RFID Reader

    Institute of Scientific and Technical Information of China (English)

    Peng Yang; Yan Li; Li-Jun Jiang; Feng Yang

    2011-01-01

    A loop antenna for near field readers is proposed.Through periodic interdigital capacitors,the phase of the current on the loop is compensated and kept in phase.Hence,a loop with a perimeter of one wavelength at 900 MHz achieves a uniform near magnetic field distribution inside the loop.A novel method is proposed to evaluate the performance of the coplanar waveguide (CPW) to coplanar stripline (CPS) transition,which is used as a balun for the feeding network in this paper.This loop antenna has a 70 MHz operating bandwidth and 12 cm maximum reading range when the output power is 24 dBm,which is suitable for most near field radio frequency identification (RFID) applications.

  16. 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

  17. Design of a Single-Arm Archimedean Spiral Antenna Used for UHF Detection%一种用于超高频电磁信号检测的单臂阿基米德螺旋天线的设计

    Institute of Scientific and Technical Information of China (English)

    喇元; 吴俊锋; 欧小波

    2014-01-01

    研究了一种50Ω同轴电缆直接馈电的单臂阿基米德螺旋天线,通过优化仿真设计了天线各项硬件参数,实现了其在UHF(超高频)段的工作。通过锥形金属片过渡馈电的方式保证了天线结构的稳定性,克服了单臂阿基米德螺旋天线偏心馈电带来的不良影响。通过改进天线的终端结构,节约了天线制作材料,提升了天线的整体性能。通过仿真分析研究了天线介质材料、馈电圆锥角、天线占空比等对天线性能的影响,并进行了优化设计。结果表明,设计的天线结构简单无需馈电巴伦,其工作频带为:1.15GHz~2.4GHz,具有良好的圆极化特性,在工作频带范围内天线最大辐射方向具有5 dB以上的增益,基本满足超高频电磁信号的检测要求。%A kind of single-arm archimedean spiral antenna which can be directly fed by a 50Ωcoaxial cable is stud-ied in this paper. In order to make the antenna work in the ultra-high frequency band, every antenna parameter is op-timized under the circumstance of simulation. The stability of the antenna structure is guaranteed by using a conical metal to feed it transitively, and the shortcomings of the eccentric feeding way used in the single-arm Archimedean an-tenna can also be eliminated. The material used for manufacturing the antenna can be saved by changing the terminal structure of the antenna, meanwhile the performance of the antenna can be improved. This paper also investigates the influence caused by the dielectric materials, the feed cone angle and the antenna duty ratio, then the antenna is opti-mized according to the conclusion. The simulation results show that the antenna is balun-free and can work in the 1. 15GHz~2. 4GHz frequency band. What’s more the antenna realizes the circular polarization and the peak gain can be more than 5dB within the frequency band. So the antenna can meet the requirements of the ultra-high frequency band detection.

  18. Development of a micro dual beam fluorometric detector specific for microchip analysis of benzo[a]pyrene and benzo[k]fluoranthene in diesel exhaust particulate samples.

    Science.gov (United States)

    Masaki, Hiroyuki; Susaki, Hironori; Korenaga, Takashi

    2005-09-01

    We developed a device and some systems for detecting benzo[a]pyrene (B[a]P) and benzo[k]fluoranthene (B[k]F). The device uses a UV light-emitting diode that emits light with a wavelength of 370 nm and a violet laser diode that emits light with a wavelength of 395 nm as excitation light sources. The detection method is based on the following observation: characteristic fluorescence is emitted from both B[a]P and B[k]F, with intensities up to 10 times greater than those from 22 other polycyclic aromatic hydrocarbons (PAHs). The excitation and emission wavelengths for fluorescence from B[a]P and B[k]F are 370 and 429 nm, and 395 and 429 nm, respectively. Further, we calculated their concentrations in diesel exhaust particles by means of two calibration curves determined using a mixture of 24 PAHs. The detection limits of the proposed device with a microchip are 5.58 microg L(-1) for B[a]P and 6.03 microg L(-1) for B[k]F. We applied this method to analyze B[a]P or B[k]F contained in three types of diesel exhaust particles, and the results agreed well with those obtained by liquid chromatography.

  19. Water vapour at high redshift : Arecibo monitoring of the megamaser in MG J0414+0534

    NARCIS (Netherlands)

    Castangia, P.; Impellizzeri, C. M. V.; McKean, J. P.; Henkel, C.; Brunthaler, A.; Roy, A. L.; Wucknitz, O.; Ott, J.; Momjian, E.

    2011-01-01

    Aims: The study of water masers at cosmological distances would allow us to investigate the parsec-scale environment around powerful radio sources, to probe the physical conditions of the molecular gas in the inner parsecs of quasars, and to estimate their nuclear engine masses in the early universe

  20. 78 FR 21907 - Energy Answers Arecibo, LLC: Notice of Intent To Prepare a Supplemental Final Environmental...

    Science.gov (United States)

    2013-04-12

    ... processing building; processed refuse fuel storage building; boiler and steam turbine; emission control... Industrial Development Company (PRIDCO) served as lead agency in preparation of a Final EIS prepared...

  1. The Arecibo Legacy Fast ALFA Survey: The Galaxy Population Detected by ALFALFA

    CERN Document Server

    Huang, Shan; Giovanelli, Riccardo; Brinchmann, Jarle

    2012-01-01

    Making use of HI 21 cm line measurements from the ALFALFA survey (alpha.40) and photometry from the Sloan Digital Sky Survey (SDSS) and GALEX, we investigate the global scaling relations and fundamental planes linking stars and gas for a sample of 9417 common galaxies: the alpha.40-SDSS-GALEX sample. In addition to their HI properties derived from the ALFALFA dataset, stellar masses (M_*) and star formation rates (SFRs) are derived from fitting the UV-optical spectral energy distributions. 96% of the alpha.40-SDSS-GALEX galaxies belong to the blue cloud, with the average gas fraction f_HI = M_HI/M_* ~ 1.5. A transition in SF properties is found whereby below M_* ~ 10^9.5 M_sun, the slope of the star forming sequence changes, the dispersion in the specific star formation rate (SSFR) distribution increases and the star formation efficiency (SFE) mildly increases with M_*. The evolutionary track in the SSFR-M_* diagram, as well as that in the color magnitude diagram are linked to the HI content; below this trans...

  2. ESI-PR07, Arecibo, Puerto Rico 2000 (Environmental Sensitivity Index Map)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Environmental Sensitivity Index (ESI) maps are an integral component in oil-spill contingency planning and assessment. They serve as a source of information in the...

  3. Research on PRNG Suitable for UHF RFID Tag%UHF RFID标签的伪随机数发生器研究

    Institute of Scientific and Technical Information of China (English)

    高树静; 王洪君

    2013-01-01

    With the development of Internet of Things,the application of RFID is becoming more and more prevalent.The security of RFID has been a hot topic in recent years.Due to the limitation of cost and power consumption,the security components in EPC Class 1 Generation 2(C1G2) passive tags are only random number generator (RNG) and Cyclic Redundancy Code (CRC).The design of RNG with low hardware complexity is critical to the security of C1G2 tag.A simple hash function,named M-hash,which is suitable to be realized in hardware was proposed.Furthermore,a pseudo-random number generator M-PRNG was designed based on one-wayness of M-hash.The M-PRNG is based on LFSR and has low hardware complexity which is suitable to passive devices like C1G2 tag.It is proved that the random sequences generated by the M-PRNG are fully compatible with EPC C1G2 protocol and successfully passe the most demanding randomness test NIST.%随着物联网的普及,RFID的应用也越来越广泛,对其安全性的研究是近几年的热点.由于成本和计算资源的限制,EPC1类2代(C1G2)无源标签中的安全部件只有随机数发生器和CRC.低复杂性随机数发生器的设计对于C1G2标签的安全是非常关键的.提出一种适于硬件实现的简单哈希函数M-hash,并利用M-hash的单向性设计了一种伪随机数发生器M-PRNG.M-PRNG以LFSR为核心器件,结构简单,适用于C1G2标签等无源器件.经过验证,M-PRNG所产生的随机序列完全符合C1G2协议的要求,并成功通过了NIST测试.

  4. Design and Implementation of UHF RFID Reader Based on Nios II%基于Nios II的UHF RFID读写器设计与实现

    Institute of Scientific and Technical Information of China (English)

    张福洪; 肖怀锋; 方洪灿; 邓朝日

    2009-01-01

    基于FPGA的数字基带系统是超高频频段射频识别读写器中的关键部分.根据EPCglobal Class 1 Gen 2标准,用Verilog语言编写了脉冲间隔编码模块和双相空号解码模块,并用C语言编写了其驱动程序,生成组件模块.组件作为Nios II嵌入系统的模块,可以重复使用.对于应用程序开发者,不用了解硬件结构就可以使用标准C 函数操作组件,使得开发简便快捷,节省了时间和成本.

  5. Temperature Effect on the Tropospheric Radio Signal Strength for UHF Band at Terengganu, Malaysia

    Directory of Open Access Journals (Sweden)

    Roshidah Mat

    2016-10-01

    Full Text Available In tropospheric layer, radio waves can propagate in a number of different physical mechanisms such as free-space propagation or line-of-sight propagation, reflection, transmission, diffraction, scattering and wave guiding. The constituents in weather such as the wind, air temperature and atmospheric water content may combine in many ways. Certain combinations can cause radio signals to be heard hundreds of miles beyond the ordinary range of radio communications. This study investigates the effect of weather (temperature on radio wave propagation up to 9GHz. Continuous-wave (CW envelope fading waveforms were recorded over a period of the one-hour using patch antenna. The observations were conducted at KUSZA Observatory, East Coast Environmental Research Institute (ESERI, UniSZA which is situated in Merang, Terengganu. Spectrum Analyser was used for RFI measurement and weather station for weather effect. The graphs of radio signal attenuation for weather parameter (temperature against time were plotted. The findings indicate that there is a relationship between radio signals with the change of temperature. The correlation between RFI frequencies and temperature give negative effect for frequency 945 MHz, was r = -0.085, while for 383 MHz (r = 0.249, 1800 MHz (r = 0.268 and 2160 MHz (r = 0.134. These findings will benefit radio wave propagation research field which includes radio astronomy observations, space science, wireless communication, satellite, antenna and mobile communication and also electromagnetic radiation (EMR research for health.

  6. Analysis and Design of a Quasi-TEM Slotted Tube Resonator for UHF-MRI

    OpenAIRE

    ALIANE, Kamila; BENABDALLAH, NADIA; BENAHMED, Nasreddine; BOUHMIDI, RACHID; Bendimerad, Fethi Tarik

    2012-01-01

    Using the finite element method (FEM) and method of moments (MoM) in two dimensions, the electromagnetic (EM) analysis and design of a quasi-TEM slotted tube resonator (STR) are presented. The modeling of this resonator consists in analyzing the even- and odd-mode characteristic impedances (Z0e, Z0o),effective dielectric constants (εeffe , εeffo), the primary inductive and capacitive matrices ([L], [C]) and simulates the frequency response of S11 at the R...

  7. Investigation of a Biocompatible Polyurethane-Based Isotropically Conductive Adhesive for UHF RFID Tag Antennas

    Science.gov (United States)

    Yang, Cheng; Yuen, Matthew M. F.; Gao, Bo; Ma, Yuhui; Wong, C. P.

    2011-01-01

    As a candidate dispersant for silver-based isotropically conductive adhesives (ICAs), polyurethane (PU) is an environmentally benign material that can withstand a high deformation rate and that exhibits excellent reliability. In this work we investigated methyl ethyl ketoxime (MEKO) blocked isophorone diisocyanate (IPDI) and MEKO blocked hexamethylene diisocyanate (HDI) as dispersant materials, and we characterize the electrical conductivity, mechanical properties, and reliability of these PU-based ICAs with silver-flake filler content ranging from 30 wt.% to 75 wt.%. Results of temperature-humidity testing (THT) at 85°C and 85% relative humidity (RH) and thermal cycling testing (TCT) at -40°C to 125°C show that these ICAs have excellent reliability. Our experimental results suggest that the MEKO blocked PU dispersants are suitable for preparing ultralow-cost, flexible, high-performance ICAs for printing antennas for ultrahigh-frequency radiofrequency identification (RFID) tags. These tags can potentially be used for identifying washable items and food packaging.

  8. Ultra Low Power, Radiation Tolerant UHF Radio Technologies for In Situ Communication Applications

    Science.gov (United States)

    Lay, N. E.

    2001-01-01

    For future deep space missions, significant reductions in the mass and power requirements for short-range telecommunication systems will be critical in enabling a wide variety of new mission concepts. These possibilities include penetrators, gliders, miniature rovers, and sensor networks. Under joint funding from NASA's Cross Enterprise and JPL's Telecommunications and Mission technology programs, recent development activity has focused on the design of ultralow mass and power transceiver systems and subsystems suitable for operation in a flight environment. For these efforts, the functionality of the transceiver has been targeted towards a specific Mars communications scenario. However, the overall architecture is well suited to any short or medium range application where a remote probe will aperiodically communicate with a base station, possibly an orbiter, for the eventual purpose of relaying science information back to Earth. In 2001, these sponsors have been augmented with collaborative expertise and funding from JPL's Center for Integrated Space Microsystems in order to migrate existing concepts and designs to a System on a Chip (SOAC) solution. Additional information is contained in the original extended abstract.

  9. Antennas for VHF/UHF personal radio: A theoretical and experimental study of characteristics and performance

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Hansen, Flemming

    1977-01-01

    , and it is shown how antenna impedance, gain, and radiation patterns can be calculated taking the presence of the body into account. For very short antennas the results indicate that radiation from the body may dominate over the radiation contributed by the antenna itself, and that the presence of the body can...... increase the antenna efficiency considerably, indicating that even very short antennas may provide acceptable radiation efficiencies. The results of the theoretical work are supported by measurements on practical antennas. Quarter-wave and short antennas of the helical type are compared with respect...

  10. Tutorial on Set-Up and Communications Delays for all UHF SATCOM DAMA Modes of Operation

    Science.gov (United States)

    2007-11-02

    2J 00 ~ - CU CUCA U C zo ca o2 ).caC 0 C *0 - _ C CU :2 U ~ U 4) - - 4)4)le 4) 0CU) U C 4) CAUC - U ~ . 2H = U o2 4) U, ) U, U e n u 2i- 2 2...C - U7 Cu U2.0. - U)Cu U) 0o6 ) Cu 0 fl)) co >Cu-d Cu CuC m2 0. 0u u Cuca C E4 4)CV X U Cu- Cu3 .. Cu CuU -U- z wU w WI- L U_ 0H t= w z <UP_ C) 0t I

  11. The tolerances in the design of two-resonator solid-state bandpass UHF filters

    Directory of Open Access Journals (Sweden)

    M. E. Il'chenko

    1983-12-01

    Full Text Available It is calculated insertion loss of cavity filter, and obtained formulas that allow to find the relation between the relative change in loss and variation coefficients. Experimental technique of finding communication resonators coefficients and transmission lines with each other was proposed. An example of the practical use of the results of the article to substantiate the accuracy of the installation of dielectric resonators in the design of microstrip dielectric filter was considered.

  12. Characterization of Propagation Path Loss at Vhf/Uhf Bands for Ilorin ...

    African Journals Online (AJOL)

    Path loss exponent, standard deviation and building penetration loss are ... for an environment, coverage planning and propagation analysis could be done easily. ... MHz frequencies along ten routes in Ilorin City in Kwara State of Nigeria.

  13. An UHF frequency-modulated continuous wave wind profiler - receiver and audio module development

    OpenAIRE

    Garrido López, David

    2010-01-01

    Projecte final de carrera fet en col.laboració amb University of Massachusetts - Amherst, the Microwave Sensing Laboratory (MIRSL) The measurement of winds and processes taking place in the atmosphere is a fun- damental requirement in both research and operational meteorology. This project is focused on the processes taking place in the lower troposphere called the atmospheric boundary layer (ABL). The ABL is important meteorologically in terms of assessing of convective in...

  14. Comparison of Anisotropic versus Isotropic Metamaterials in Low Profile UHF Antenna Design

    Science.gov (United States)

    2014-08-01

    S11, and/or VSWR of the antenna. All simulations have been run using the time domain solver of CST Studio Suite 2013, and adaptive meshing has been...dimension a served in sections 2.1–2.2, where fr = 200 MHz and w = 0 in. Dimension a1 represents the value of λr/2 that maintains fr = 200 MHz when the...and 5b. a0 b a1 fr (MHz) d δ PW L 30.68 13.64 9.7 192.5 4.1 0.27 0.7 8.5 Immediately, figures 6a and 6b show relative stability of the realized

  15. SDR-Ready Standardized Waveforms for Tactical VHF and UHF Communications for NATO

    Science.gov (United States)

    2010-09-01

    network layer, logical link control ( LLC ), the medium access control (MAC) layer, the link encryption, and the physical layer (PHY). Each layer is...Interface to LLC or user level Interface to MAC Layer Header Interpretation Interpret and route LCC_PDU Main Logic Service Selection from application... Interleaving Burst composition & Modulation RF front-end PHY_PAR Demodulation Decoding Deinterleving Carrier and symbol Synchronization Burst Detection R F

  16. Low modulation index RF signal detection for a passive UHF RFID transponder

    Institute of Scientific and Technical Information of China (English)

    Liu Zhongqi; Zhang Chun; Li Yongming; Wang Zhihua

    2009-01-01

    ower into voltage signal, the detection sensitivity is ensured over a wide power range with low power consumption of 8.6μW. The chip is implemented in UMC 0.18μm mix-mode CMOS technology, and the chip area is 0.06 mm2.

  17. Locatable-body temperature monitoring based on semi-active UHF RFID tags.

    Science.gov (United States)

    Liu, Guangwei; Mao, Luhong; Chen, Liying; Xie, Sheng

    2014-03-26

    This paper presents the use of radio-frequency identification (RFID) technology for the real-time remote monitoring of body temperature, while an associated program can determine the location of the body carrying the respective sensor. The RFID chip's internal integrated temperature sensor is used for both the human-body temperature detection and as a measurement device, while using radio-frequency communication to broadcast the temperature information. The adopted RFID location technology makes use of reference tags together with a nearest neighbor localization algorithm and a multiple-antenna time-division multiplexing location system. A graphical user interface (GUI) was developed for collecting temperature and location data for the data fusion by using RFID protocols. With a puppy as test object, temperature detection and localization experiments were carried out. The measured results show that the applied method, when using a mercury thermometer for comparison in terms of measuring the temperature of the dog, has a good consistency, with an average temperature error of 0.283 °C. When using the associated program over the area of 12.25 m2, the average location error is of 0.461 m, which verifies the feasibility of the sensor-carrier location by using the proposed program.

  18. Investigation of the UHF mobile-radio propagation channel in a temperate-zone forested environment

    Science.gov (United States)

    White, Kenneth J.

    1986-08-01

    Experimental verification of the stochastic power-spectral-density theory of radio propagation, as applied to a mobile receiver in a forested environment, is presented. Using a novel technique to achieve fractional-hertz resolution of the diffuse and direct wave components of the Doppler-spread received spectrum, the resultant data taken at 432 MHz shows that the angle of arrival of the diffuse component of the incident energy at the receive antenna is described by an uniform probability density function for both vertical and horizontal polarizations. Given an 8.8 km transmission path with the signal penetrating 1.3 km of forest just before reaching the receiver, the ratio of coherent (direct wave) intensity to total received signal power is 42% for horizontal polarization and 5% for vertical polarization. The results of the research indicate that long transmission paths in foliage are better characterized by a forward-scattering mechanism than by a lateral wave model.

  19. a Highly-Accurate and Fast Ray Tracing Sysyem for HF and UHF Simulations

    Science.gov (United States)

    Jones, J. C.; Richards, G. P.

    2016-12-01

    Accurate and fast ray tracing is critical for radiowave propagation tools and applications. A ray tracer needs to be accurate to reduce accumulated errors which come from the myriad of models (ionospheric electron density, magnetic field, ion density, neutral molecule density, absorption, land surface, ocean surface, and potentially others) required for accurate simulation. A ray tracer must also be fast to make the use of applications practical. Here we introduce NINJART Is Not Just Another Ray Tracer (NINJART), a highly accurate and fast ray tracing system. NINJART consists of an embarrassingly parallel algorithm rigorously solving the 3-D Hasselgrove equations with a Runge-Kutta adaptive step quadrature rule to accurately trace high frequency to ultra-high frequency radiowaves. It is capable of a wide range of propagation modes from multi-ground hops to vertical and near vertical incidence rays, chordal modes, and other esoteric paths. It is capable of using a variety of ionospheric models to include operational data assimilative or empirical models depending on the needs of the user. It can forward and backward ray trace, calculate time of flight, find the focus factor for signals near the skip zone and calculate the angle of arrival from a known transmitter to a known receiver location. Additionally NINJART uses magnetic field data from various models including the International Geomagnetic Reference Field to reduce the inaccuracies introduced by the simple dipole model, which is commonly used by other ray tracers, in calculating the effects of magneto-ionic splitting thereby allowing accurate traces of both the ordinary and extraordinary mode rays. The NINJART algorithm is a heterogeneous system utilizing the CUDA programming language to take advantage of the computing power of graphical processing units. This allows tracing of thousands of rays concurrently. NINJART achieves additional processing savings, without sacrificing accuracy, by use of an adaptive step size algorithm which uses smaller steps when the direction of the ray is rapidly changing and larger steps when it's relatively straight. NINJART considers surface interactions by incorporating high-resolution terrain models for ground orientation, soil type, and moisture to calculate the absorption of the signal along the path.

  20. Novel Method to measure the gain of UHF directional antennas using distance scan

    NARCIS (Netherlands)

    Witvliet, Ben A.; Maanen, van Erik; Bentum, Mark J.; Slump, Cornelis H.; Schiphorst, Roel

    2014-01-01

    A novel antenna gain measurement method is described which uses power transfer values that are measured while varying the distance between two antennas (Distance Scan). It can be executed with simple means and is cost-effective. The Distance Scan method yields derived free space antenna gain values

  1. ZEBRA TECHNOLOGIE揭开HF和UHF RRD的神秘面纱

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    作为无线射频识别(RFID)技术的行业先锋.Zebra Technologies Corporation(纳斯达克股票代码为.ZBRA)日前宣布.其已在网站上发布了最新的学习资源.旨在帮助企业更深刻地了解RFID技术.从而做出更明智的选择。

  2. Autodyne characteristics of stabilized UHF-oscillators at a strong reflected signal

    Directory of Open Access Journals (Sweden)

    Noskov V. Ya.

    2011-11-01

    Full Text Available Calculations and examinations of phase, amplitude, frequency and amplitude-frequency characteristics are fulfilled for the autodyne system stabilized by the external high-Q cavity as well as spectral characteristics under condition of exact and non-exact cavity tuning and the variations of distance to reflector. The distinguished peculiarities of the autodyne response at the small and large reflected signal are described. Experimental research results are discussed fulfilled on an example of the hybrid-integrated oscillator on Gunn diode of 8-mm-range, which confirm qualitatively the theoretic results.

  3. Ultra Low Power, Radiation Tolerant UHF Radio Technologies for In Situ Communication Applications

    Science.gov (United States)

    Lay, N. E.

    2001-01-01

    For future deep space missions, significant reductions in the mass and power requirements for short-range telecommunication systems will be critical in enabling a wide variety of new mission concepts. These possibilities include penetrators, gliders, miniature rovers, and sensor networks. Under joint funding from NASA's Cross Enterprise and JPL's Telecommunications and Mission technology programs, recent development activity has focused on the design of ultralow mass and power transceiver systems and subsystems suitable for operation in a flight environment. For these efforts, the functionality of the transceiver has been targeted towards a specific Mars communications scenario. However, the overall architecture is well suited to any short or medium range application where a remote probe will aperiodically communicate with a base station, possibly an orbiter, for the eventual purpose of relaying science information back to Earth. In 2001, these sponsors have been augmented with collaborative expertise and funding from JPL's Center for Integrated Space Microsystems in order to migrate existing concepts and designs to a System on a Chip (SOAC) solution. Additional information is contained in the original extended abstract.

  4. Profiling river surface velocities and volume flow estimation with bistatic UHF RiverSonde radar

    Science.gov (United States)

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

    2003-01-01

    From the velocity profiles across the river, estimates of total volume flow for the four methods were calculated based on a knowledge of the bottom depth vs position across the river. It was found that the flow comparisons for the American River were much closer, within 2% of each other among all of the methods. Sources of positional biases and anomalies in the RiverSonde measurement patterns along the river were identified and discussed.

  5. FSL based estimation of white space availability in UHF TV bands in Bergvliet, South Africa

    CSIR Research Space (South Africa)

    Lysko, AA

    2012-09-01

    Full Text Available The paper describes the predictions made for Bergvliet, South Africa in terms of the availability of the frequency spectrum occupied by analogue TV broadcast around that area. The focus is made on the availability of under-used TV channels...

  6. Assessment of Options for Improving the 5-KHZ UHF Dama Waveform

    Science.gov (United States)

    2007-11-02

    designated orderwire segment of the TDMA frame. B. Comunications . Upon receipt of the orderwire message from the controller, the calling party (user A...ENSURE SAME LESSONS ARE NOT LEARNED IN SUBSEQUENT YEARS TO BE INSTITUTIONALIZED E. AGILE PROVIDER 94, REVISED BATTLEFIELD ELECTRONIC CEOI SYSTEM

  7. Microstrip Array Antenna with 16 Patches for UHF Band Television Signal Reception

    Directory of Open Access Journals (Sweden)

    Yulindon Yulindon

    2013-01-01

    Full Text Available There are 2 commonly known equipment for the reception of television broadcasts i.e. using a parabolic antenna connected to satellite receiver and a wire or pipe antenna that directly connected to the television receiver. Receiving the signal by means of a parabolic antenna is more expensive because it requires additional tools , namely satellite receivers, so generally the people like to choose the easier way by direct receiving the signal using wire antenna. The antenna construction which made of aluminum pipes has a weakness easily bent or broken on the assembling phase as well as when there are high winds causing the antenna mast collapsed, confirmed that the antenna is bent, loose or broken elements. The paper relates to a microstrip antenna for reception of television signals using material printed circuit boards or printed circuit board (PCB which is a thin but strong in the form of a number of patches array separated in a certain distance.

  8. Stacked-patch antenna with switchable propagating mode for UHF body-centric communications

    NARCIS (Netherlands)

    Scanlon, W.G.; Chandran, A.R.

    2009-01-01

    The ability to electronically switch between off-body and on-body communications is a useful feature for wearable antenna applications. Therefore, we present a novel stacked-patch antenna with a switched propagation mode for body-centric communications at 2.45 GHz. Mounted 2 mm above a muscle-tissue

  9. UHF coplanar-slot antenna for aircraft-to-satellite data communications

    Science.gov (United States)

    Myhre, R. W.

    1979-01-01

    The initiative for starting the Aircraft-to-Satellite Data Relay (ASDAR) Program came from a recognition that much of the world's weather originates in the data sparse area of the tropics which are primarily ocean. The ASDAR system consists of (1) a data acquisition and control unit to acquire, store and format these data; (2) a clock to time the data sampling and transmission periods; and (3) a transmitter and low-profile upper hemisphere coverage antenna to relay the formatted data via satellite to the National Weather Service ground stations, as shown schematically. The low-profile antenna is a conformal antenna based on the coplanar-slot approach. The antenna is circular polarized and has an on-axis gain of nearly 2.5 dB and a HPBW greater than 90 deg. The discussion covers antenna design, radiation characteristics, flight testing, and system performance.

  10. AN/GRC-171 Rivet Switch Multichannel UHF/AM Transceiver

    Science.gov (United States)

    1975-03-01

    o. 6 o.S3 ■o-iT^ -o.S’Z f o. 4 O/ -^■Z, ~ f9 .S +1.4 2.1 6-g 7. 7 / 2 g o.o 𔃻-1 JisA- - o.l fo.S ici-r FORM ,__ AFCS MAY «S 199...9/* zs L-f-ZO 7s. to ZJ-S’ 59.9s GENERAL PURPOSE FORM AFCS iaoot/io«i . o.^...,«.., ,,,,„ i ,„„„ lIBS^pnnwWWIW^ Bpp ^BWTWRPIP»^ 4.3.15 AN

  11. An UHF Frequency-Modulated Continuous Wave Wind Profiler - Development and Initial Results

    Science.gov (United States)

    2009-09-01

    more solitary. Gabriel Garcia Marquez iv ACKNOWLEDGMENTS At each stage in one’s life, there comes this time when the mind is already jumping excitedly...antennas that were purchased from Gabriel Antennas. The back to front ratio for the antennas is specified to be -22 dB but no antenna pattern was

  12. The Effect of Refractivity on Propagation at UHF and VHF Frequencies

    Directory of Open Access Journals (Sweden)

    I. Alam

    2016-01-01

    Full Text Available This paper is using weather parameters to investigate the effect of refractivity on propagation in the first kilometer of the atmosphere over the English Channel for a long transhorizon path of 140 km. Different refractivity profiles are constructed based on meteorological data taken from the UK Meteorological Office in order to investigate the effects of refractivity on propagation. The analysis is made for the hourly experimental path loss between the transmitter and receiver obtained from the experimental setup comprised of two communication links. The frequency of operation of the first link is 2015 MHz and that of the second link is 240 MHz. Parabolic equation method is modelled to get an hourly modelled path loss corresponding to each hourly experimental path loss to be analyzed for the said communication links. The correlation between the modelled path loss and experimental path loss is computed for refractivity distribution recommended by the ITU and predicted profiles. It is inferred from the simulated and experimental results that little or no influence exists by the evaporation duct upon path loss at 2015 MHz specifically for a long path of 140 km over the sea.

  13. Equatorial Scintillation of Satellite Signals at uhf and L-band for Two Different Elevation Angles

    Science.gov (United States)

    1980-05-01

    Equatorial Scintillation, Planetary and Space Science, vol 20, no 12, p 1999- 2014 , 1972. 4 Briggs, BH and Parkin, IA, On the Variation of Radio Star and...Paulson and RUF Hopkins, 2 May 1977. 3. Koster, JR, Equatorial Scintillation, Planetary and Space Science, vol 20, no 12, p 1999- 2014 , 1972. 4. Briggs...6 -_ _ __ _ __ __B-20 - -- - -- ,r ... EN14IT9PC~r CA L417 ,L4!1𔄃N O’_AN 135- 39r9 ’. ICERi HI 1979z I-I 9 LO t I L2 t3 -1 5l IEi I GHT 9 1Ll. It 1 1

  14. DICE THROW/UHF/SHF Transmission Experiment. Volume 3. Final Data Reduction and Interpretation

    Science.gov (United States)

    1979-08-01

    Time from North Oscuro Peak Camera Site . ....... . . .. 119 B-34 DICE THROW Cloud,-Height and Width Averaged from R-1, PR, and NOP Camera Sites...from the main transmitter was received at North Oscuro Peak to phase-lock the remote transmitter. The transmitter power levels ranged between 10 and...North Oscuro Peak) Phase Repeater 135,60 196,200 1440 Receiving Site 1 131,614 196,191 1429 (Main) Receiving Site 2 131,843 195,995 1429 (Outrigger 1

  15. HI content and other structural properties of galaxies in the Virgo cluster from the Arecibo Legacy Fast ALFA Survey

    CERN Document Server

    Gavazzi, Giuseppe; Haynes, Martha P; Fabello, Silvia; Fumagalli, Michele; Kent, Brian R; Koopmann, Rebecca A; Brosch, Noah; Hoffman, G Lyle; Salzer, John J; Boselli, Alessandro

    2008-01-01

    We report the results of an HI blind survey of 80deg^2 of the Virgo cluster, based on the 08deg 10^7.5-8 M_sun. 156/187 (83%) sources are identified with optical galaxies from the Virgo Cluster Catalogue (Binggeli et al. 1985), all but 8 with late-type galaxies. Ten sources are not associated with optical galaxies and were found to correspond to tidally-disrupted systems (see Kent et al. 2007 and Haynes, Giovanelli and Kent 2007). The remaining 21 (11%) are associated with galaxies that are not listed in the Virgo Cluster Catalogue. For all sources with an optical counterpart in the Sloan Digital Sky Survey, we analyzed i-band SDSS plates to measure optical structural parameters. We find that in the Virgo cluster: i) HI inhabits galaxies that are structurally similar to ordinary late-type galaxies; ii) their HI content can be predicted from their optical luminosity; iii) low surface brightness galaxies have low optical luminosity and contain small quantities of neutral hydrogen; iv) low surface brightness, m...

  16. Observations of NEAs at Arecibo Observatory and NASA's IRTF: Combining Radar and Thermal Measurements to Better Understand NEA Physical Properties

    Science.gov (United States)

    Nolan, Michael C.; Vervack, R. J.; Howell, E. S.; Magri, C.; Fernandez, Y. R.; Taylor, P. A.; Mueller, M.; Rivkin, A. S.; Benner, L. A. M.

    2010-10-01

    As we sample ever-smaller sizes of near-Earth asteroids (NEAs), we see an increasing variation in the range of physical properties. Radar experiments show a diverse range of shapes, surface features, and rotation states among NEAs. Infrared observations of these objects are equally varied, illustrating a range of spectral types and thermal characteristics. While spacecraft missions will reveal details of a few NEAs, only ground-based observations will provide an overall understanding of the population of these small bodies, for which the size and albedo distributions are still poorly understood. The goal of our investigation is to use both radar images and near-IR spectra to better understand the regolith of different types and shapes of NEAs. The regolith on an asteroid surface controls its thermal properties and often its radar reflectance as well, and at smaller sizes the irregular shape plays an increasingly important role. To accomplish our goal, we have established a program in which we choose NEAs that will be observed well enough with radar to have high-quality shape models and also observe these objects with SpeX at the NASA IRTF (2-4 microns) at several different viewing geometries and rotation phases to see how the inferred thermal properties depend on the detailed shape. We then use this knowledge to quantify the systematic biases in existing thermal models that are based on simple assumptions such as spherical shape or zero thermal inertia. We will present a summary of our observations to date and preliminary results of the thermal modeling.

  17. The HI Mass Function and Velocity Width Function of Void Galaxies in the Arecibo Legacy Fast ALFA Survey

    CERN Document Server

    Moorman, Crystal M; Hoyle, Fiona; Pan, Danny C; Haynes, Martha P; Giovanelli, Riccardo

    2014-01-01

    We measure the HI mass function (HIMF) and velocity width function (WF) across environments over a range of masses $7.2<\\log(M_{HI}/M_{\\odot})<10.8$, and profile widths $1.3\\log(km/s)<\\log(W)<2.9\\log(km/s)$, using a catalog of ~7,300 HI-selected galaxies from the ALFALFA Survey, located in the region of sky where ALFALFA and SDSS (Data Release 7) North overlap. We divide our galaxy sample into those that reside in large-scale voids (void galaxies) and those that live in denser regions (wall galaxies). We find the void HIMF to be well fit by a Schechter function with normalization $\\Phi^*=(1.37\\pm0.1)\\times10^{-2} h^3Mpc^{-3}$, characteristic mass $\\log(M^*/M_{\\odot})+2\\log h_{70}=9.86\\pm0.02$, and low-mass-end slope $\\alpha=-1.29\\pm0.02$. Similarly, for wall galaxies, we find best-fitting parameters $\\Phi^*=(1.82\\pm0.03)\\times10^{-2} h^3Mpc^{-3}$, $\\log(M^*/M_{\\odot})+2\\log h_{70}=10.00\\pm0.01$, and $\\alpha=-1.35\\pm0.01$. We conclude that void galaxies typically have slightly lower HI masses than ...

  18. Altitude characteristics of plasma turbulence excited with the Tromso superheater

    Energy Technology Data Exchange (ETDEWEB)

    Djuth, F.T.; Elder, J.H. (Geospace Research Inc., El Segundo, CA (United States)); Stubbe, P.; Kohl, H. (Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany)); Sulzer, M.P. (Arecibo Observatory (Puerto Rico)); Rietveld, M.T. (EISCAT Scientific Association, Ramfjordbotn (Norway))

    1994-01-01

    Langmuir/ion turbulence excited with the upgraded high-power (1.2-GW effective radiated power) HF heating facility at Tromso, Norway, has been recently studied with the European Incoherent Scatter VHF and UHF incoherent scatter radars. In this report the authors focus on the altitudinal development of the turbulence observed at the highest HF power levels available. Quite remarkably, the observed plasma turbulence plunges downward in altitude over timescales of tens of seconds following HF beam turn-on; the bottom altitude is generally reached after [approximately]30 s. This phenomenon has a well-defined HF power threshold. It is most likely caused by changes in the electron density profile brought about by HF heating of the electron gas. If this is the case, then the heat source must be nonlinearly dependent on HF power. Overall, the characteristics of the Tromso turbulence are quite distinctive when compared to similar high-resolution measurements made at Arecibo Observatory, Puerto Rico. After HF transmissions have been made for tens of seconds at Tromso, billowing altitude structures are often seen, in sharp contrast to layers of turbulence observed at Arecibo. 17 refs., 3 figs.

  19. A Search for Meteoroid Lunar Impact Generated Electromagnetic Pulses

    Science.gov (United States)

    Kesaraju, Saiveena; Mathews, John D.; Vierinen, Juha; Perillat, Phil; Meisel, David D.

    2016-11-01

    Lunar white light flashes associated with meteoroid impacts are now regularly observed using modest optical instrumentation. In this paper, we hypothesize that the developing, optically-dense hot ejecta cloud associated with these hypervelocity impacts also produce an associated complex plasma component that rapidly evolves resulting in a highly-transient electro magnetic pulse (EMP) in the VHF/UHF spectral region. Discovery of the characteristics and event frequency of impact EMPs would prove interesting to meteoroid flux and complex plasma physics studies especially if EMPs from the same event are detected from at least two locations on the Earth with relative delays appropriate to the propagation paths. We describe a prototype observational search, conducted in May 2014, for meteoroid lunar-impact EMPs that was conducted using simultaneous, overlapping-band, UHF radio observations at the Arecibo (AO; Puerto Rico) and Haystack (HO, Massachusetts, USA) Observatories. Monostatic/bistatic lunar radar imaging observations were also performed with HO transmitting and HO/AO receiving to confirm tracking, the net delay, and the pointing/timing ephemeris at both observatories. Signal analysis was performed using time-frequency signal processing techniques. Although, we did not conclusively identify EMP returns, this search detected possible EMPs and we have confirmed the search paradigm and established the sensitivity of the AO-HO system in detecting the hypothesized events. We have also characterized the difficult radio-frequency interference environment surrounding these UHF observations. We discuss the wide range of terrestrial-origin, Moon-bounce signals that were observed which additionally validate the observational technique. Further observations are contemplated.

  20. A High Performance Power Recovery Circuit for UHF RFID Tags%适于UHF RFID标签芯片的高性能电源恢复电路

    Institute of Scientific and Technical Information of China (English)

    冯筱; 文光俊; 陈健; 王耀; 刘佳欣

    2012-01-01

    A high performance power recovery circuit was designed for ISO 18000-6C standard) which was implemented in TSMC's 0. 18 μm CMOS mixed signal process. Simulation results showed that the circuit had an energy conversion efficiency (PCE) of 29. 88%, a temperature coefficient of 2. 4X 10-5/°C as temperature changing from -20 ℃to 80℃ , and a PSRR of 91. 4 dB @ 10 Hz and 34. 5 dB @ 10 MHz. Measured results showed that the tag could work at a minimum input RF power of -9. 5 dBm, when the rectifying efficiency reached 23. 1%, and two regulated output voltages stabilized at 1. 8 ± 0. 1 V and 1. 0 ±0. 05 V, respectively. The circuit occupies a chip area of about 0. 166 mm2.%针对ISO 18000-6C标准,提出一种双电压输出稳压电路,有效降低了整体芯片功耗.基于Cadence Spectre设计仿真平台和TSMC 0.18μm CMOS混合信号工艺进行设计并流片.在-20℃~80℃温度范围内,工艺角从ff到SS变化,仿真得到整流电路的能量转换效率(PCE)为29.88%,稳压电路的温度系数为2.4×10-5/℃,电源噪声抑制比(PSRR)为91.4 dB@10 Hz和34.5 dB @10 MHz.同时对芯片进行测试,标签可以工作的最低输入射频功率为-9.5 dBm,此时整流效率可达23.1%,稳压高低两路电压输出分别稳定在1.8±0.1V和1.0±0.05 V,芯片面积约为0.166 mm2.