WorldWideScience

Sample records for hf vhf uhf

  1. 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...

  2. 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.

  3. 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

  4. 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

  5. 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.

  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. [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.

  8. 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.

  9. 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.

  10. Structure, optical properties and thermal stability of HfErO films deposited by simultaneous RF and VHF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Nanjing University of Posts and Telecommunications, School of Tongda, Nanjing (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); He, H.J.; Zhang, Z.; Jin, C.G.; Yang, Y.; Wang, Y.Y.; Ye, C. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Zhuge, L.J. [Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Soochow University, Analysis and Testing Center, Suzhou (China); Wu, X.M. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Chinese Academy of Sciences, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Shanghai (China)

    2015-01-23

    HfErO films are deposited on Si substrates by simultaneous radio frequency (RF) and very high frequency (VHF) magnetron sputtering technique. The content of the doped ingredient of Er and the body composition of HfO{sub x} are, respectively, controlled through the VHF and RF powers. Low content of Er doping in the HfErO films can be achieved, because the VHF source of 27.12 MHz has higher ion energy and lower ion flux than the RF source resulting in low sputtering rate in the magnetron sputtering system. The structure, optical properties and thermal stability of the HfErO films are investigated in this work. Results show that the doped content of Er is independently controlled by the VHF power. The oxygen vacancies are created by the Er incorporation. The hafnium in the HfErO films forms mixed valence of Hf{sup 2+} and Hf{sup 4+}. The HfErO films are composed with the structures of HfO{sub 2}, HfO and ErO{sub x}, which can be optimized through the VHF power. At high VHF power, the Hf-Er-O bonds are formed, which demonstrates that the Er atoms are doped into the lattice of HfO{sub 2} in the HfErO films. The HfErO films have bad thermal stability as the crystallization temperature decreases from 900 to 800 C. After thermal annealing, cubic phase of HfO{sub 2} are stabilized, which is ascribed to the oxygen vacancies creation by the Er incorporation. The optical properties such as the refractive index and the optical band gap of the HfErO films are optimized by the VHF power. (orig.)

  11. 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…

  12. 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…

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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...

  18. 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...

  19. 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.

  20. Signal processing techniques for phase-coded HF-VHF radars

    Directory of Open Access Journals (Sweden)

    J. A. Baskaradas

    2003-06-01

    Full Text Available HF-VHF radar techniques are easy to employ and commonly used in geophysical applications. They include deep radio soundings, used for probing the ionosphere, stratosphere-mesosphere measurement, weather forecast and radio-glaciology. Fast algorithms and powerful processors facilitate the development of several kinds of low power radars, but the reduction of the transmitted power has to be compensated by on-line processing of an encoded signal to maintain a favorable signal-to-noise ratio suitable for detection. Moreover, radars have to reconstruct return echoes with different travel times due to various origins (multi-path, adjacent objects, etc.. Such needs can be accomplished by means of signal phase coding and one of the most attractive is the reversal phase code. The composite echo signal must be processed to extract the physical information useful for the measurement considered. In this paper some algorithms used for on-line processing of phase-coded signals will be described, both in time and frequency domain.

  1. Arctic and Antarctic polar mesosphere summer echoes observed with oblique incidence HF radars: analysis using simultaneous MF and VHF radar data

    Directory of Open Access Journals (Sweden)

    T. Ogawa

    2004-12-01

    Full Text Available Polar mesosphere summer echoes (PMSEs have been well studied using vertical incidence VHF radars at northern high-latitudes. In this paper, two PMSE events detected with the oblique incidence SuperDARN HF radars at Hankasalmi, Finland (62.3° N and Syowa Station, Antarctica (69.0° S, are analyzed, together with simultaneous VHF and medium-frequency (MF radar data. Altitude resolutions of the HF radars in the mesosphere and the lower thermosphere are too poor to know exact PMSE altitudes. However, a comparison of Doppler velocity from the HF radar and neutral wind velocity from the MF radar shows that PMSEs at the HF band appeared at altitudes within 80-90km, which are consistent with those from previous vertical incidence HF-VHF radar results. The HF-VHF PMSE occurrences exhibit a semidiurnal behavior, as observed by other researchers. It is found that in one event, PMSEs occurred when westward semidiurnal winds with large amplitude at 85-88km altitudes attained a maximum. When the HF-VHF PMSEs were observed at distances beyond 180km from MF radar sites, the MF radars detected no appreciable signatures of echo enhancement.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides

  2. Active Modification of VHF and HF PMSE during the 2009 EISCAT Campaign

    Science.gov (United States)

    Mahmoudian, A.; Scales, W.; Kosch, M.; Singer, A.; Rietveld, M. T.

    2009-12-01

    Polar Mesospheric Summer Echoes (PMSE) are strong echoes that have been typically observed in the frequency range from 50MHz to 1.3GHz and in the altitude about 85Km. The PMSE is produced by scattering from electron irregularities due to electron charging on the irregular subvisible mesospheric dust layer. The radar echoes occur at half the radar wavelength therefore the wavelength of the irregularities are roughly in the range of 10cm to 10m. In recent experiments, the EISCAT ground based ionospheric heating facility was used to produce an artificial enhancement in electron temperature in dust layer.Important information can be obtained from temporal behavior of the electron irregularities during turn on or turn off the radio wave heating. Considering the temporal behavior of electron irregularities during heating process provides diagnostic information about dust layer. In the first part of the presentation, the radar data obtained during an experimental campaign at the European Incoherent Scatter Scientific Association (EISCAT) facility in Tromso, Norway in July 2009 is discussed. The measurement was set up with 3 minutes heating cycle in which the heater is on for 40 seconds to increase electron temperature in the specific area in the ionosphere and after 40 seconds, the heater is turned off. At the same time the scatter radar signal also is recorded to analyze temporal behavior during turn on and turn off of the heater. Radar scattering at 224 MHz (VHF) and 7.953 MHz (HF) frequency bands was observed. Modulation in the PMSE is observed. In the second part of the presentation, a computational model is used to provide interpretation of the data. A one dimensional computational model is used to study PMSE during radio wave heating. There are different parameters which vary with temperature such electron-neutral collision frequency, recombination coefficient and dust charging process. The model includes ions, electrons and dust. The ions and electrons are treated

  3. 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

  4. Dicty_cDB: VHF420 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF420 (Link to dictyBase) - - - Contig-U11380-1 VHF420P (Link to Original site) VHF...420F 574 VHF420Z 554 VHF420P 1108 - - Show VHF420 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-A/VHF420Q.Seq.d/ Representative seq. ID VHF...420P (Link to Original site) Representative DNA sequence >VHF420 (VHF420Q) /CSM/VH/VHF4-A/VHF...qqqhrlpqqi*nhq*nlmnl*hhliifqlvinqf ikkiqlkmnienyl*iivmiqn*iiyiyivkrylkvnqpplnyqm*mvsivlwdsmqnni hf

  5. 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.

  6. 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。

  7. 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....

  8. Practical Limits in the Sensitivity-Linearity Trade-off for Radio Telescope Front Ends in the HF and VHF-low Bands

    CERN Document Server

    Tillman, R H; Brendler, J

    2016-01-01

    Radio telescope front ends must have simultaneously low noise and sufficiently-high linearity to accommodate interfering signals. Typically these are opposing design goals. For modern radio telescopes operating in the HF (3-30 MHz) and VHF-low (30-88 MHz) bands, the problem is more nuanced in that front end noise temperature may be a relatively small component of the system temperature, and increased linearity may be required due to the particular interference problems associated with this spectrum. In this paper we present an analysis of the sensitivity-linearity trade off at these frequencies, applicable to existing commercially-available monolithic microwave integrated circuit (MMIC) amplifiers in single-ended, differential, and parallelized configurations. This analysis and associated findings should be useful in the design and upgrade of front ends for low frequency radio telescopes. The analysis is demonstrated explicitly for one of the better-performing amplifiers encountered in this study, the Mini-Ci...

  9. Analysis of Spacecraft VHF/UHF Shielding Effectiveness Based on Equivalent Admittance Model%等效导纳模型分析航天器VHF/UHF频段屏蔽效能

    Institute of Scientific and Technical Information of China (English)

    张玉廷; 李冉; 高文军; 吕争; 张华

    2016-01-01

    针对VHF/UHF频段航天器舱体屏蔽处理难度大的问题,提出一种基于等效导纳模型的屏蔽效能分析方法.该方法将屏蔽舱体孔缝等效为波导结构,基于变分法原理建立水平电容和垂直电感模型,对参数失配和舱体厚度影响进行导纳匹配和孔缝宽度参数修正.采用传输线理论建立屏蔽效能分析数学模型.算例对比表明算法具有较高的分析精度,可有效分析孔缝不位于舱体中心位置和孔缝长度非波长整数倍时的屏蔽效能,并可准确预测舱体的谐振效应.将其应用到航天器舱体屏蔽效能分析中,对比结果表明算法可有效满足工程应用要求.

  10. 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

  11. 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.

  12. Spatial and temporal variations of small-scale plasma turbulence parameters in the equatorial electrojet: HF and VHF radar observational results

    Directory of Open Access Journals (Sweden)

    G. Manju

    2005-06-01

    Full Text Available The spatial and temporal variations of various parameters associated with plasma wave turbulence in the equatorial electrojet (EEJ at the magnetic equatorial location of Trivandrum (8.5° N, 77° E; dip 0.5° N are studied for the first time, using co-located HF (18MHz and VHF (54.95MHz coherent backscatter radar observations (daytime in the altitude region of 95-110km, mostly on magnetically quiet days. The derived turbulence parameters are the mean electron density irregularity strength (δn/n, anomalous electron collision frequency (νe* and the corrected east-west electron drift velocity (Vey. The validity of the derived parameters is confirmed using radar data at two different frequencies and comparing with in-situ measurements. The behaviour of δn/n in relation to the backscattered power during weak and strong EEJ conditions is also examined to understand the growth and evolution of turbulence in the electrojet.

  13. Comparison of D-region Doppler drift winds measured by the SuperDARN Finland HF radar over an annual cycle using the Kiruna VHF meteor radar

    Directory of Open Access Journals (Sweden)

    N. F. Arnold

    Full Text Available The SuperDARN chain of oblique HF radars has provided an opportunity to generate a unique climatology of horizontal winds near the mesopause at a number of high latitude locations, via the Doppler shifted echoes from sources of ionisation in the D-region. Ablating meteor trails form the bulk of these targets, but other phenomena also contribute to the observations. Due to the poor vertical resolution of the radars, care must be taken to reduce possible biases from sporadic-E layers and Polar Mesospheric Summer echoes that can affect the effective altitude of the geophysical parameters being observed. Second, there is strong theoretical and observational evidence to suggest that the radars are picking up echoes from the backward looking direction that will tend to reduce the measured wind strengths. The effect is strongly frequency dependent, resulting in a 20% reduction at 12 MHz and a 50% reduction at 10 MHz. A comparison of the climatologies observed by the Super-DARN Finland radar between September 1999 and September 2000 and that obtained from the adjacent VHF meteor radar located at Kiruna is also presented. The agreement between the two instruments was very good. Extending the analysis to the SuperDARN Iceland East radar indicated that the principles outlined above could be applied successfully to the rest of the SuperDARN network.

    Key words. Ionosphere (ionosphere-atmosphere interactions; instruments and techniques – Meteorology and atmospheric dynamics (waves and tides

  14. 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.

  15. The structure of turbulence in the middle and lower atmosphere seen by and deduced from MF, HF and VHF radar, with special emphasis on small-scale features and anisotropy

    Directory of Open Access Journals (Sweden)

    W. K. Hocking

    Full Text Available An overview of the turbulent structures seen by MF, HF and VHF radars in the troposphere, stratosphere and mesosphere is presented, drawing on evidence from previous radar measurements, in situ studies, laboratory observations, observations at frequencies other than those under focus, and modelling studies. We are particularly interested in structures at scales less than one radar pulse length, and smaller than the beam width, and especially the degree of anisotropy of turbulence at these scales. Previous radar observations are especially important in regard to the degree of anisotropy, and we highlight the role that these studies have had in furthering our understanding in this area. The contrasts and similarities between the models of anisotropic turbulence and specular reflection are considered. The need for more intense studies of anisotropy at MF, HF and VHF is especially highlighted, since this is an area in which these radars can make important contributions to the understanding of atmospheric turbulence.

    Key words. Meteorology and atmospheric dynamics (turbulence – Atmospheric composition and structure (instruments and techniques – History of geophysics (atmospheric sciences

  16. 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

  17. 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。

  18. VHF signal power suppression in stratiform and convective precipitation

    Directory of Open Access Journals (Sweden)

    A. J. McDonald

    2006-03-01

    Full Text Available Previous studies have indicated that VHF clear-air radar return strengths are reduced during periods of precipitation. This study aims to examine whether the type of precipitation, stratiform and convective precipitation types are identified, has any impact on the relationships previously observed and to examine the possible mechanisms which produce this phenomenon. This study uses a combination of UHF and VHF wind-profiler data to define periods associated with stratiform and convective precipitation. This identification is achieved using an algorithm which examines the range squared corrected signal to noise ratio of the UHF returns for a bright band signature for stratiform precipitation. Regions associated with convective rainfall have been defined by identifying regions of enhanced range corrected signal to noise ratio that do not display a bright band structure and that are relatively uniform until a region above the melting layer.

    This study uses a total of 68 days, which incorporated significant periods of surface rainfall, between 31 August 2000 and 28 February 2002 inclusive from Aberystwyth (52.4° N, 4.1° W. Examination suggests that both precipitation types produce similar magnitude reductions in VHF signal power on average. However, the frequency of occurrence of statistically significant reductions in VHF signal power are very different. In the altitude range 2-4 km stratiform precipitation is related to VHF signal suppression approximately 50% of the time while in convective precipitation suppression is observed only 27% of the time. This statistical result suggests that evaporation, which occurs more often in stratiform precipitation, is important in reducing the small-scale irregularities in humidity and thereby the radio refractive index. A detailed case study presented also suggests that evaporation reducing small-scale irregularities in humidity may contribute to the observed VHF signal

  19. Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms

    Science.gov (United States)

    Deshpande, Manohar; Piepmeier, Jeffrey

    2015-01-01

    Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms. Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane

  20. 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

  1. PMSE Observations With the Tri-Static EISCAT VHF Radars

    Science.gov (United States)

    Mann, I.; Tjulin, A.; Häggström, I.

    2013-12-01

    The polar mesospheric summer echoes (PMSE) are generated in the ionosphere at roughly 80 to 90 altitude by electron irregularities in the presence of charged solid particles and PMSE are most likely observed when ice particles form onto nanodust. PMSE formation is an important part in understanding mesospheric processes, but is also an interesting example for dusty plasma phenomena occurring in space. To investigate the phenomena that lead to formation of PMSE it is helpful to study the radar reflectivity of the mesosphere at different angles. PMSE were previously studied at different aspect angles in order to better understand the scattering process. Another way is observing PMSE from multiple sites simultaneously. During this summer the EISCAT radars that are located in Northern Scandinavia could for the first time be used for tri-static observations in the VHF band and we carried out observations during three subsequent days in June 2013. The radar signal was transmitted in zenith direction with the EISCAT VHF antenna near Tromsø (69.59 deg N, 19.23 deg E) and the scattered signal was measured from Tromsø, Kiruna (67.86 deg N, 20.44 deg E) and Sodankylä (67.36 deg N, 26.63 deg E). Zenith observations were simultaneously carried out with the Tromsø UHF radar (933 MHz). Other groups have previously reported the observations of PMSE simultaneously with the EISCAT VHF and UHF radars, but with a much lower occurrence rate for the UHF. UHF observations made during this campaign are dominated by incoherent scatter. The VHF system in Tromsø detected PMSE for a large fraction of the observation time. The VHF receivers in Kiruna and Sodankylä were pointed at typical PMSE heights above the Tromsø transmitter and detected radar reflections at the same time and altitude as the Tromsø radar. These observations are among the first tri-static observations of PMSE. Preliminary results from the campaign will be presented and discussed.

  2. Design VHF Antennas for Space Borne Receivers for SmallSats

    Science.gov (United States)

    Deshpande, Manohar

    2017-01-01

    Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane.

  3. First wind shear observation in PMSE with the tristatic EISCAT VHF radar

    Science.gov (United States)

    Mann, I.; Häggström, I.; Tjulin, A.; Rostami, S.; Anyairo, C. C.; Dalin, P.

    2016-11-01

    The Polar Summer Mesosphere has the lowest temperatures that occur in the entire Earth system. Water ice particles below the optically observable size range participate there in the formation of strong radar echoes (Polar Mesospheric Summer Echoes, PMSE). To study PMSE we carried out observations with the European Incoherent Scatter (EISCAT) VHF and EISCAT UHF radar simultaneously from a site near Tromsø (69.58°N, 19.2272°E) and observed VHF backscattering also with the EISCAT receivers in Kiruna (67.86°N, 20.44°E) and Sodankylä (67.36°N, 26.63°E). This is one of the first tristatic measurements with EISCAT VHF, and we therefore describe the observations and geometry in detail. We present observations made on 26 June 2013 from 7:00 to 13:00 h UT where we found similar PMSE patterns with all three VHF receivers and found signs of wind shear in PMSE. The observations suggest that the PMSE contains sublayers that move in different directions horizontally, and this points to Kelvin-Helmholtz instability possibly playing a role in PMSE formation. We find no signs of PMSE in the UHF data. The electron densities that we derive from observed incoherent scatter at UHF are at PMSE altitudes close to the noise level but possibly indicate reduced electron densities directly above the PMSE.

  4. 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.

  5. Dicty_cDB: VHF449 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF449 (Link to dictyBase) - - - Contig-U14527-1 VHF449P (Link to Original site) VHF...449F 596 VHF449Z 195 VHF449P 771 - - Show VHF449 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-C/VHF449Q.Seq.d/ Representative seq. ID VHF...449P (Link to Original site) Representative DNA sequence >VHF449 (VHF449Q) /CSM/VH/VHF4-C/VHF4...qh*ervmhqliqnilnwklpmiiklilfgrm qkiinqkiglhfit--- ---ixfkifki*n*xtxkkkfsxfxkxxlxxxffxxfldxx*xlglxnivxxsxxflk

  6. Dicty_cDB: VHF877 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF877 (Link to dictyBase) - - - Contig-U16274-1 VHF877P (Link to Original site) VHF...877F 529 VHF877Z 662 VHF877P 1171 - - Show VHF877 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-D/VHF877Q.Seq.d/ Representative seq. ID VHF...877P (Link to Original site) Representative DNA sequence >VHF877 (VHF877Q) /CSM/VH/VHF8-D/VHF...ce (All Frames) Frame A: synl*i*kkcqklkiqvs*dlmihhxqqhfhxlllshqkllvvlkslvekv*ippnsrls vlkihskvhmslqni*qelhhl

  7. Dicty_cDB: VHF335 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF335 (Link to dictyBase) - - - Contig-U16260-1 VHF335P (Link to Original site) VHF...335F 646 VHF335Z 700 VHF335P 1326 - - Show VHF335 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-B/VHF335Q.Seq.d/ Representative seq. ID VHF...335P (Link to Original site) Representative DNA sequence >VHF335 (VHF335Q) /CSM/VH/VHF3-B/VHF...DSLI QRAGIIADKVSGDMRYMSCRADEQERGITIKSSSVSLHFEMPKEDKLPAGCTSHEFLINL IDSPGHVDFSSEVTAALRVTDGALVVIDCVEGVCVQTETVLR

  8. Dicty_cDB: VHF832 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF832 (Link to dictyBase) - - - Contig-U16260-1 VHF832P (Link to Original site) VHF...832F 427 VHF832Z 691 VHF832P 1098 - - Show VHF832 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-B/VHF832Q.Seq.d/ Representative seq. ID VHF...832P (Link to Original site) Representative DNA sequence >VHF832 (VHF832Q) /CSM/VH/VHF8-B/VHF...sequence LSSAKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQXRGITIKSSSVSLHFEMPKEDKLP

  9. Dicty_cDB: VHF467 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF467 (Link to dictyBase) - - - Contig-U16473-1 VHF467P (Link to Original site) VHF...467F 499 VHF467Z 555 VHF467P 1034 - - Show VHF467 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-C/VHF467Q.Seq.d/ Representative seq. ID VHF...467P (Link to Original site) Representative DNA sequence >VHF467 (VHF467Q) /CSM/VH/VHF4-C/VHF...ated Amino Acid sequence IIQKTFIYIFIKMISKTSLLLLLLSIVALASAISVQRVPIADVTSAPAHFVQNKLA

  10. Dicty_cDB: VHF221 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF221 (Link to dictyBase) - - - Contig-U16260-1 VHF221P (Link to Original site) VHF...221F 533 VHF221Z 417 VHF221P 930 - - Show VHF221 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-A/VHF221Q.Seq.d/ Representative seq. ID VHF...221P (Link to Original site) Representative DNA sequence >VHF221 (VHF221Q) /CSM/VH/VHF2-A/VHF2...lated Amino Acid sequence LSSAKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHF

  11. Dicty_cDB: VHF603 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF603 (Link to dictyBase) - - - Contig-U16439-1 VHF603P (Link to Original site) VHF...603F 495 VHF603Z 580 VHF603P 1055 - - Show VHF603 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF6-A/VHF603Q.Seq.d/ Representative seq. ID VHF...603P (Link to Original site) Representative DNA sequence >VHF603 (VHF603Q) /CSM/VH/VHF6-A/VHF...rnirapl*i*vshslvslnqlppqrtkfvkaglghfgivsmlmv islsrsf*xslkrnmvwifqcylvklhfymlsslirklkrkd*r*kxhnxmkpsqrnhyq ki

  12. Dicty_cDB: VHF858 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF858 (Link to dictyBase) - - - Contig-U16260-1 VHF858P (Link to Original site) VHF...858F 371 VHF858Z 699 VHF858P 1050 - - Show VHF858 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-C/VHF858Q.Seq.d/ Representative seq. ID VHF...858P (Link to Original site) Representative DNA sequence >VHF858 (VHF858Q) /CSM/VH/VHF8-C/VHF...GKTTLSDSLIQRXGIIADKV SGDMRYMSCRADEQDRGITIKSSSVSLHFEMPKEDKLPAGCTSHEFLINLIDSPXHVDF- -- ---NHEWDKNDAMNIWSFGPEGN

  13. Dicty_cDB: VHF511 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF511 (Link to dictyBase) - - - Contig-U15704-1 VHF511P (Link to Original site) VHF...511F 534 VHF511Z 812 VHF511P 1326 - - Show VHF511 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-A/VHF511Q.Seq.d/ Representative seq. ID VHF...511P (Link to Original site) Representative DNA sequence >VHF511 (VHF511Q) /CSM/VH/VHF5-A/VHF...ydlfnr--- ---qlnqlns*kpiytivlvmimixmmktinliivd*leiikmvhrkfthsqmiihf*fk hywiyiklhl

  14. Dicty_cDB: VHF132 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF132 (Link to dictyBase) - - - Contig-U16423-1 VHF132P (Link to Original site) VHF...132F 611 VHF132Z 657 VHF132P 1248 - - Show VHF132 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-B/VHF132Q.Seq.d/ Representative seq. ID VHF...132P (Link to Original site) Representative DNA sequence >VHF132 (VHF132Q) /CSM/VH/VHF1-B/VHF...nce update 2002.10.25 Translated Amino Acid sequence ii*fsfffnllkinidkff*RISHFMPIGNNKDNDGTTLNISGLTISDKSSSTSS

  15. Dicty_cDB: VHF307 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF307 (Link to dictyBase) - - - Contig-U16305-1 VHF307P (Link to Original site) VHF...307F 583 VHF307Z 606 VHF307P 1169 - - Show VHF307 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-A/VHF307Q.Seq.d/ Representative seq. ID VHF...307P (Link to Original site) Representative DNA sequence >VHF307 (VHF307Q) /CSM/VH/VHF3-A/VHF...NIGVTFIGPGSYAMHALGDKIESKRIAKEAGVSVVPGYIGEVDGMDH VIKIANEIGY--- ---XSISPDILYIAKVENVRHSIHF

  16. Dicty_cDB: VHF737 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF737 (Link to dictyBase) - - - Contig-U11426-1 VHF737P (Link to Original site) VHF...737F 537 VHF737Z 507 VHF737P 1024 - - Show VHF737 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF7-B/VHF737Q.Seq.d/ Representative seq. ID VHF...737P (Link to Original site) Representative DNA sequence >VHF737 (VHF737Q) /CSM/VH/VHF7-B/VHF...xvitinxvqiyxrs*vn*xisqklnipwyxvmqplqllqkhsnfnktivkfhwilnvp n*lkafvlyhfivnig*siipsyqlkssypiikyywyhpiyqinyhdhq

  17. Dicty_cDB: VHF641 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF641 (Link to dictyBase) - - - Contig-U11064-1 VHF641P (Link to Original site) VHF...641F 132 VHF641Z 617 VHF641P 729 - - Show VHF641 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF6-B/VHF641Q.Seq.d/ Representative seq. ID VHF...641P (Link to Original site) Representative DNA sequence >VHF641 (VHF641Q) /CSM/VH/VHF6-B/VHF6...vhqqnqllqlqqlqqqlllqllqq--- ---hsiksytlsfksflwsigil*simey*nqtrwwfsfq*a*m*dgyvsipivyqsls* *rfcksywyhf

  18. Dicty_cDB: VHF202 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF202 (Link to dictyBase) - - - Contig-U15304-1 VHF202P (Link to Original site) VHF...202F 247 VHF202Z 519 VHF202P 746 - - Show VHF202 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-A/VHF202Q.Seq.d/ Representative seq. ID VHF...202P (Link to Original site) Representative DNA sequence >VHF202 (VHF202Q) /CSM/VH/VHF2-A/VHF2...nslated Amino Acid sequence *iih*kknmihfqkqlqqwvd*n**kkii*qimlmrilchgih*NHRFFNNIP

  19. Dicty_cDB: VHF510 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF510 (Link to dictyBase) - - - Contig-U15722-1 VHF510P (Link to Original site) VHF...510F 448 VHF510Z 848 VHF510P 1276 - - Show VHF510 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-A/VHF510Q.Seq.d/ Representative seq. ID VHF...510P (Link to Original site) Representative DNA sequence >VHF510 (VHF510Q) /CSM/VH/VHF5-A/VHF...QDTTNDNDCKRYTTNVIFQC--- ---ctcp**pfgxgceftrgpldcstpngtcdnntgnctchnehfgnsceftrcpldcst pngtcdnntgnctchnehfgngc

  20. Dicty_cDB: VHF277 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF277 (Link to dictyBase) - - - Contig-U15541-1 VHF277P (Link to Original site) VHF...277F 450 VHF277Z 524 VHF277P 954 - - Show VHF277 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-D/VHF277Q.Seq.d/ Representative seq. ID VHF...277P (Link to Original site) Representative DNA sequence >VHF277 (VHF277Q) /CSM/VH/VHF2-D/VHF2...KSDN QIEELNQYINPMLDFVVLINDDPERYDSVTSAALALLGDLAQAMGDSIRNLLNN Frame B: tysskkwifiklwpmqiinlkvfvqkpnhf*pmhhnktf

  1. 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.

  2. 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

  3. Dicty_cDB: VHF437 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF437 (Link to dictyBase) - - - Contig-U15043-1 VHF437P (Link to Original site) VHF4...37F 661 VHF437Z 461 VHF437P 1102 - - Show VHF437 Library VH (Link to library) Clone ID VHF4...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-B/VHF437Q.Seq.d/ Representative seq. ID VHF4...37P (Link to Original site) Representative DNA sequence >VHF437 (VHF437Q) /CSM/VH/VHF4-B/VHF4... Score E Sequences producing significant alignments: (bits) Value VHF437 (VHF437Q) /CSM/VH/VHF4-B/VHF4

  4. Dicty_cDB: VHF434 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF434 (Link to dictyBase) - - - Contig-U16429-1 VHF434P (Link to Original site) VHF4...34F 565 VHF434Z 716 VHF434P 1261 - - Show VHF434 Library VH (Link to library) Clone ID VHF4...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-B/VHF434Q.Seq.d/ Representative seq. ID VHF4...34P (Link to Original site) Representative DNA sequence >VHF434 (VHF434Q) /CSM/VH/VHF4-B/VHF4... Score E Sequences producing significant alignments: (bits) Value VHF434 (VHF434Q) /CSM/VH/VHF4-B/VHF434Q.Se

  5. Dicty_cDB: VHF461 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF461 (Link to dictyBase) - - - Contig-U11551-1 VHF461P (Link to Original site) VHF4...61F 646 VHF461Z 261 VHF461P 887 - - Show VHF461 Library VH (Link to library) Clone ID VHF4... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-C/VHF461Q.Seq.d/ Representative seq. ID VHF4...61P (Link to Original site) Representative DNA sequence >VHF461 (VHF461Q) /CSM/VH/VHF4-C/VHF4...NA Score E Sequences producing significant alignments: (bits) Value VHF461 (VHF461Q) /CSM/VH/VHF4-C/VHF461Q.

  6. Dicty_cDB: VHF163 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF163 (Link to dictyBase) - - - Contig-U11129-1 VHF163P (Link to Original site) VHF1...63F 611 VHF163Z 654 VHF163P 1245 - - Show VHF163 Library VH (Link to library) Clone ID VHF1...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-C/VHF163Q.Seq.d/ Representative seq. ID VHF1...63P (Link to Original site) Representative DNA sequence >VHF163 (VHF163Q) /CSM/VH/VHF1-C/VHF1...nt alignments: (bits) Value VHF163 (VHF163Q) /CSM/VH/VHF1-C/VHF163Q.Seq.d/ 2357 0.0 VHM584 (VHM584Q) /CSM/VH

  7. Dicty_cDB: VHF187 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF187 (Link to dictyBase) - - - Contig-U16363-1 VHF187P (Link to Original site) VHF1...87F 549 VHF187Z 707 VHF187P 1236 - - Show VHF187 Library VH (Link to library) Clone ID VHF1...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF187Q.Seq.d/ Representative seq. ID VHF1...87P (Link to Original site) Representative DNA sequence >VHF187 (VHF187Q) /CSM/VH/VHF1-D/VHF1...* Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF187 (VHF1

  8. Dicty_cDB: VHF196 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available iol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF196Q.Seq.d/ Representative seq. ID - (Link to Original site) Representa...tive DNA sequence >VHF196 (VHF196Q) /CSM/VH/VHF1-D/VHF196Q.Seq.d/ AATAAAGAAAATTAAAT

  9. Dicty_cDB: VHF458 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF458 (Link to dictyBase) - - - Contig-U16260-1 VHF458P (Link to Original site) VHF4...58F 608 VHF458Z 699 VHF458P 1287 - - Show VHF458 Library VH (Link to library) Clone ID VHF4...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-C/VHF458Q.Seq.d/ Representative seq. ID VHF4...58P (Link to Original site) Representative DNA sequence >VHF458 (VHF458Q) /CSM/VH/VHF4-C/VHF4...sh*srfshqkekrfsprnprsdkfhekl*ti*valxfsk Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF4

  10. Dicty_cDB: VHF122 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available px xsl*pperekv*pqksqiltnstknskqfkshfefs Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF...VH (Link to library) VHF122 (Link to dictyBase) - - - Contig-U16260-1 VHF122P (Link to Original site) VHF...122F 573 VHF122Z 653 VHF122P 1206 - - Show VHF122 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-A/VHF122Q.Seq.d/ Representative seq. ID VHF...122P (Link to Original site) Representative DNA sequence >VHF122 (VHF122Q) /CSM/VH/VHF1-A/VHF

  11. 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.

  12. Dicty_cDB: VHF275 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF275 (Link to dictyBase) - - - Contig-U15033-1 - (Link to Original site) VHF...275F 582 - - - - - - Show VHF275 Library VH (Link to library) Clone ID VHF275 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF2-D/VHF275Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF275 (VHF275Q) /CSM/VH/VHF2-D/VHF275Q.Seq.d/ ATAGTTACAAATAAATA...yyiyfhyllf*ypkt*livkiii*qngiy*hhfqvhqekmlmy*ivmveli iyq*viiqhilvn*lmeqeldgiiiqqmlmvwli*ifqim*igi**iigqdqvahilvvg efqhf

  13. Dicty_cDB: VHF446 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF446 (Link to dictyBase) - - - Contig-U12653-1 - (Link to Original site) VHF...446F 547 - - - - - - Show VHF446 Library VH (Link to library) Clone ID VHF446 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF4-B/VHF446Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF446 (VHF446Q) /CSM/VH/VHF4-B/VHF446Q.Seq.d/ AAATAATTATTTTTATT...mlniq ni*qhshthi*medymlvmfsqspkqnlcvnskd*wvkefyshlhsivlvcqlkhvlin* rkklnnlvvhqfsqllkknqfkk*qqq*kkihfhlnqrkqk

  14. Dicty_cDB: VHF107 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF107 (Link to dictyBase) - - - Contig-U16260-1 - (Link to Original site) VHF...107F 610 - - - - - - Show VHF107 Library VH (Link to library) Clone ID VHF107 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF1-A/VHF107Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF107 (VHF107Q) /CSM/VH/VHF1-A/VHF107Q.Seq.d/ AACTCTCGAGTGCAAAA...GKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHFEMPKEDKLPAGCTSHEFLINLIDSPGHVDFS SEVTAALRVTDGALVVIDCVEGVCVQ

  15. Dicty_cDB: VHF173 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF173 (Link to dictyBase) - - - Contig-U11936-1 - (Link to Original site) VHF...173F 575 - - - - - - Show VHF173 Library VH (Link to library) Clone ID VHF173 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF173Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF173 (VHF173Q) /CSM/VH/VHF1-D/VHF173Q.Seq.d/ GTTTCAAAATCTTCTCT...fktfi**lys ftkifnk******y**hhhhfhqhq****qqyrlttttttixttttttttisnnsktfln flsqiff--- Frame C: FKIFSAQLAPGASSVP

  16. Dicty_cDB: VHF675 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF675 (Link to dictyBase) - - - Contig-U10739-1 - (Link to Original site) VHF...675F 501 - - - - - - Show VHF675 Library VH (Link to library) Clone ID VHF675 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF6-D/VHF675Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF675 (VHF675Q) /CSM/VH/VHF6-D/VHF675Q.Seq.d/ ATATCACACAAAAACAG...rccqtkeshstckqnr*tkeqtr itfsscryhfpsisc**iit*r*irstc*kyrtslfscrp*ifsi*nfrvssqylfn

  17. Dicty_cDB: VHF875 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF875 (Link to dictyBase) - - - Contig-U15307-1 - (Link to Original site) - - VHF...875Z 679 - - - - Show VHF875 Library VH (Link to library) Clone ID VHF875 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF8-D/VHF875Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF875 (VHF875Q) /CSM/VH/VHF8-D/VHF875Q.Seq.d/ XXXXXXXXXXTCACATT...mlvlmvks lvlidlvclhqvmpl*nn*v*llki**tfqnnknkik*ikikmln Frame B: ---tftsslhfhs*lcwcw*rwsnssts*nrfrssydsklgchs

  18. Dicty_cDB: VHF656 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF656 (Link to dictyBase) - - - Contig-U14796-1 - (Link to Original site) - - VHF...656Z 249 - - - - Show VHF656 Library VH (Link to library) Clone ID VHF656 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF6-C/VHF656Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF656 (VHF656Q) /CSM/VH/VHF6-C/VHF656Q.Seq.d/ XXXXXXXXXXTCCCNAA...ence (All Frames) Frame A: ---pxxppppkkkkkkkk**k**k*k**kiikkyvsdiffcffrsnlkvtnh*ftwdn*t nissvglvicfhf

  19. Dicty_cDB: VHF191 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF191 (Link to dictyBase) - - - Contig-U16260-1 - (Link to Original site) VHF...191F 400 - - - - - - Show VHF191 Library VH (Link to library) Clone ID VHF191 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF191Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF191 (VHF191Q) /CSM/VH/VHF1-D/VHF191Q.Seq.d/ AACTCTCGAGTGCAAAA...DHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHFXMPKEDKLPAGCTSHEFLINLIDSPGHVDFS SEVTAALRV--- Translated

  20. Dicty_cDB: VHF255 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF255 (Link to dictyBase) - - - Contig-U16260-1 - (Link to Original site) VHF...255F 680 - - - - - - Show VHF255 Library VH (Link to library) Clone ID VHF255 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF2-C/VHF255Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF255 (VHF255Q) /CSM/VH/VHF2-C/VHF255Q.Seq.d/ AACTCTCGAGTGCAAAA...Translated Amino Acid sequence LSSAKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHF

  1. Dicty_cDB: VHF249 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF249 (Link to dictyBase) - - - Contig-U16260-1 - (Link to Original site) VHF...249F 617 - - - - - - Show VHF249 Library VH (Link to library) Clone ID VHF249 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF2-C/VHF249Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF249 (VHF249Q) /CSM/VH/VHF2-C/VHF249Q.Seq.d/ AACTCTCGAGTGCAAAA...VIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHFEMPKEDKLPAGCTSHEFLINLIDSPGHVDFS SEVTAALRVTDGALVVIDC

  2. Dicty_cDB: VHF190 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available F0-ATPase putative regulatory protein IF1 (if1) mRNA, complete cds; nuclear gene for mitochondrial produc...VH (Link to library) VHF190 (Link to dictyBase) - - - Contig-U12594-1 - (Link to Original site) VHF1...90F 581 - - - - - - Show VHF190 Library VH (Link to library) Clone ID VHF190 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF190Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF190 (VHF190Q) /CSM/VH/VHF1-D/VHF190Q.Seq.d/ ATTTTTCATTTTAAAAA

  3. Dicty_cDB: VHF494 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF494 (Link to dictyBase) - - - Contig-U11753-1 | Contig-U13565-1 VHF4...94P (Link to Original site) VHF494F 545 VHF494Z 682 VHF494P 1207 - - Show VHF494 Library VH (Link to library) Clone ID VHF4...753-1 | Contig-U13565-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-D/VHF4...94Q.Seq.d/ Representative seq. ID VHF494P (Link to Original site) Representative DNA sequence >VHF494 (VHF4...94Q) /CSM/VH/VHF4-D/VHF494Q.Seq.d/ TTAATCGTTGTGATGAAATTGAAAATCAACGTATTCAAAGAGTTTTACTCGAAAAGAAAG

  4. Dicty_cDB: VHF478 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF478 (Link to dictyBase) - - - Contig-U11096-1 | Contig-U12663-1 VHF4...78P (Link to Original site) VHF478F 135 VHF478Z 535 VHF478P 650 - - Show VHF478 Library VH (Link to library) Clone ID VHF4...96-1 | Contig-U12663-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-D/VHF4...78Q.Seq.d/ Representative seq. ID VHF478P (Link to Original site) Representative DNA sequence >VHF478 (VHF4...78Q) /CSM/VH/VHF4-D/VHF478Q.Seq.d/ CATTACATGTTCGATTGTAGAATATTTCACAGATTTTTTTTATTTTAAAATAAATTTCCG

  5. Dicty_cDB: VHF411 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF411 (Link to dictyBase) - - - Contig-U16260-1 VHF411P (Link to Original site) VHF4...11F 618 VHF411Z 690 VHF411P 1288 - - Show VHF411 Library VH (Link to library) Clone ID VHF4...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-A/VHF411Q.Seq.d/ Representative seq. ID VHF4...11P (Link to Original site) Representative DNA sequence >VHF411 (VHF411Q) /CSM/VH/VHF4-A/VHF4...dkkatevalatrkrkglapeipdldkfhekl*ti*valefsk Homology vs CSM-cDNA Score E Sequences producing significant alig

  6. Dicty_cDB: VHF414 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF414 (Link to dictyBase) - - - Contig-U11293-1 - (Link to Original site) - - VHF4...14Z 605 - - - - Show VHF414 Library VH (Link to library) Clone ID VHF414 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF4-A/VHF414Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF414 (VHF414Q) /CSM/VH/VHF4-A/VHF414Q.Seq.d/ XXXXXXXXXXTGAACGT...g significant alignments: (bits) Value VHF414 (VHF414Q) /CSM/VH/VHF4-A/VHF414Q.Seq.d/ 1140 0.0 SHF541 (SHF54

  7. Dicty_cDB: VHF408 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF408 (Link to dictyBase) - - - Contig-U12390-1 | Contig-U13635-1 VHF4...08P (Link to Original site) VHF408F 112 VHF408Z 660 VHF408P 752 - - Show VHF408 Library VH (Link to library) Clone ID VHF4...90-1 | Contig-U13635-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-A/VHF4...08Q.Seq.d/ Representative seq. ID VHF408P (Link to Original site) Representative DNA sequence >VHF408 (VHF4...08Q) /CSM/VH/VHF4-A/VHF408Q.Seq.d/ AATTTAAAAAAAAAAAAAAAANTAANTAANTAAAATAAATAAATAANTAAAATAANTAAN

  8. Dicty_cDB: VHF441 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF441 (Link to dictyBase) - - - - VHF441P (Link to Original site) VHF441F 572 VHF4...41Z 612 VHF441P 1164 - - Show VHF441 Library VH (Link to library) Clone ID VHF441 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4...-B/VHF441Q.Seq.d/ Representative seq. ID VHF441P (Link to... Original site) Representative DNA sequence >VHF441 (VHF441Q) /CSM/VH/VHF4-B/VHF441Q.Seq.d/ AACTCTCGAGTGCAAA

  9. Dicty_cDB: VHF883 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF883 (Link to dictyBase) - - - Contig-U11297-1 | Contig-U12785-1 VHF...883P (Link to Original site) VHF883F 202 VHF883Z 486 VHF883P 668 - - Show VHF883 Library VH (Link to library) Clone ID VHF...97-1 | Contig-U12785-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-D/VHF...883Q.Seq.d/ Representative seq. ID VHF883P (Link to Original site) Representative DNA sequence >VHF883 (VHF...883Q) /CSM/VH/VHF8-D/VHF883Q.Seq.d/ GATNACATTTTTCTTTTTCAATACTCGCTCGCTTAACACACAAATTGTTGGAAAACAACA

  10. Dicty_cDB: VHF539 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF539 (Link to dictyBase) - - - Contig-U16372-1 | Contig-U16442-1 VHF...539P (Link to Original site) VHF539F 477 VHF539Z 338 VHF539P 795 - - Show VHF539 Library VH (Link to library) Clone ID VHF...72-1 | Contig-U16442-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-B/VHF...539Q.Seq.d/ Representative seq. ID VHF539P (Link to Original site) Representative DNA sequence >VHF539 (VHF...539Q) /CSM/VH/VHF5-B/VHF539Q.Seq.d/ TAGGAAGANATGCAACCTATGGGAACTACAAGACTAAATATTATAATATGGGATTGTATT

  11. Dicty_cDB: VHF147 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF147 (Link to dictyBase) - - - Contig-U11312-1 VHF147P (Link to Original site) VHF...147F 613 VHF147Z 761 VHF147P 1354 - - Show VHF147 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-B/VHF147Q.Seq.d/ Representative seq. ID VHF...147P (Link to Original site) Representative DNA sequence >VHF147 (VHF147Q) /CSM/VH/VHF1-B/VHF...**eifnri*l*qcignie*si*ystk*frstfifryc*i*kk*ys*si iis*sfk*siw***kw*w*w*w*w**ydfk*s*swfinssiynqr*ml*ksr*strcnhk lskclsnhf

  12. Dicty_cDB: VHF213 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF213 (Link to dictyBase) - - - - VHF213P (Link to Original site) VHF213F 614 VHF...213Z 650 VHF213P 1244 - - Show VHF213 Library VH (Link to library) Clone ID VHF213 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF...2-A/VHF213Q.Seq.d/ Representative seq. ID VHF213P (Link to... Original site) Representative DNA sequence >VHF213 (VHF213Q) /CSM/VH/VHF2-A/VHF213Q.Seq.d/ CTCGAGTGCAAAAAAA

  13. Dicty_cDB: VHF489 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF489 (Link to dictyBase) - - - - VHF489P (Link to Original site) VHF489F 614 VHF...489Z 416 VHF489P 1010 - - Show VHF489 Library VH (Link to library) Clone ID VHF489 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF...4-D/VHF489Q.Seq.d/ Representative seq. ID VHF489P (Link to... Original site) Representative DNA sequence >VHF489 (VHF489Q) /CSM/VH/VHF4-D/VHF489Q.Seq.d/ AACTCTCGAGTGCAAA

  14. Dicty_cDB: VHF459 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF459 (Link to dictyBase) - - - - VHF459P (Link to Original site) VHF459F 617 VHF...459Z 416 VHF459P 1013 - - Show VHF459 Library VH (Link to library) Clone ID VHF459 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF...4-C/VHF459Q.Seq.d/ Representative seq. ID VHF459P (Link to... Original site) Representative DNA sequence >VHF459 (VHF459Q) /CSM/VH/VHF4-C/VHF459Q.Seq.d/ AACTCTCGAGTGCAAA

  15. Dicty_cDB: VHF812 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF812 (Link to dictyBase) - - - Contig-U15818-1 | Contig-U16198-1 VHF...812P (Link to Original site) VHF812F 134 VHF812Z 592 VHF812P 706 - - Show VHF812 Library VH (Link to library) Clone ID VHF...18-1 | Contig-U16198-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-A/VHF...812Q.Seq.d/ Representative seq. ID VHF812P (Link to Original site) Representative DNA sequence >VHF812 (VHF...812Q) /CSM/VH/VHF8-A/VHF812Q.Seq.d/ AATTTAATATAACANTAGTATTTTTAGATTATAATATAAAATTATAAACACANTTAAAAA

  16. Lightning Imaging via VHF Emission

    Science.gov (United States)

    Kawasaki, Z.

    2015-12-01

    Osaka University has been developing interferometric lightning mapping systems for some time, first with narrow band VHF interferometers, and then with broadband digital VHF interferometers (DITF). Recently, a collaboration between New Mexico Tech and Osaka University resulted in the development of the NMT INTF. All of these interferometric lightning mapping systems have added greatly to our understanding of lightning physics. The next generation of digital broadband VHF interferometer is now being developed in Osaka, called the Lightning Imaging via VHF Emission (LIVE) interferometer. LIVE is capable of mapping lightning in real-time with sub-millisecond time resolution, or through post processing with sub-microsecond time resolution. Near-field corrections have been developed, so that sources very close to the array can be located accurately, and so that the baselines can lengthened for improved angular resolution. LIVE is capable of locating lighting over more than a 75 dB range of brightnesses, allowing the system to be extremely sensitive, and the long baselines allow for location uncertainties as low as tens of meters. Presented are observations of lightning recorded in the Kasai area of Japan, as well as the Pengerang region of Malaysia showing the capabilities of the LIVE interferometer.

  17. First HF radar measurements of summer mesopause echoes at SURA

    Directory of Open Access Journals (Sweden)

    A. N. Karashtin

    Full Text Available HF sounding of the mesosphere was first carried out at SURA in summer 1994 at frequencies in the range 8–9 MHz using one of the sub-arrays of the SURA heating facility. The observations had a range resolution of 3 km. Almost all measurements indicated the presence of strong radar returns from altitudes between 83 and 90 km with features very similar to VHF measurements of mesopause summer echoes at mid-latitudes and polar mesopause summer echoes. In contrast to VHF observations, HF mesopause echoes are almost always present.

  18. First HF radar measurements of summer mesopause echoes at SURA

    Science.gov (United States)

    Karashtin, A. N.; Shlyugaev, Y. V.; Abramov, V. I.; Belov, I. F.; Berezin, I. V.; Bychkov, V. V.; Eryshev, E. B.; Komrakov, G. P.

    1997-07-01

    HF sounding of the mesosphere was first carried out at SURA in summer 1994 at frequencies in the range 8-9 MHz using one of the sub-arrays of the SURA heating facility. The observations had a range resolution of 3 km. Almost all measurements indicated the presence of strong radar returns from altitudes between 83 and 90 km with features very similar to VHF measurements of mesopause summer echoes at mid-latitudes and polar mesopause summer echoes. In contrast to VHF observations, HF mesopause echoes are almost always present.

  19. 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.

  20. 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.

  1. Dicty_cDB: VHF475 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF475 (Link to dictyBase) - - - Contig-U15712-1 - (Link to Original site) - - VHF4...75Z 595 - - - - Show VHF475 Library VH (Link to library) Clone ID VHF475 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF4-D/VHF475Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF475 (VHF475Q) /CSM/VH/VHF4-D/VHF475Q.Seq.d/ XXXXXXXXXXTGGCATC...kfqr*rw*txfkkiiii iykfsfylnk*ink*kr Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF4

  2. Layered Polar Mesospheric Summer Echoes Observed with the Tri-Static Eiscat VHF

    Science.gov (United States)

    Mann, I.; Anyairo, C.; Häggström, I.; Tjulin, A.

    2014-12-01

    Polar mesospheric summer echoes (PMSE) are strong radar echoes that are typically observed at 50 to 500 MHz. They are often discussed in the context of dusty plasma studies and linked to e.g. the existence of charged ice particles, neutral atmospheric turbulence and atmospheric stratification. The PMSE are observed at mesospheric temperature minimum when ice particles form, though the exact path of formation is still a topic for research. Mesospheric smoke particles that are assumed to form after or during the meteor ablation process possibly contribute to the formation of the ice particles. For understanding the formation of the radar echoes their variation with scattering angle is an important parameter. We analyze PMSE observations with the tri-static EISCAT VHF radar (224 MHz) during one day in June when PMSE were observed almost continuously from 7:00 to 13:00 UT. The radar signal was transmitted and received in zenith direction with the EISCAT VHF antenna near Tromsø. The receivers in Kiruna and Sodankylä were pointed at typical PMSE heights above the Tromsø transmitter and detected radar reflections at the same time and altitude as the Tromsø radar. The altitude of the PMSE changed with time and the extension of the echoes in altitude was smaller toward the end of the observation. These observations are among the first tri-static observations of PMSE. The observations suggest that the scattering process underlying the PMSE occurs over a broad range of scattering angles. Based on the observations we will show that the spectral width of the received echoes is most likely determined by the variations within the observed volume rather than by the scattering process. The observed frequency shifts suggest a layer structure and horizontal motions that vary with altitude. UHF (933 MHz) radar observations were carried out in parallel, they display predominantly incoherent scatter and an electron density typical for the altitude. Some other studies, have in

  3. 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...

  4. 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.

  5. 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

  6. 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.

  7. Dicty_cDB: VHF730 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF730 (Link to dictyBase) - - - Contig-U15767-1 VHF730P (Link... to Original site) VHF730F 569 VHF730Z 718 VHF730P 1267 - - Show VHF730 Library VH (Link to library) Clone ID VHF730 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U15767-1 Original site URL http://dict...INKKA RISWPDGFKYFFVDNQAGDSESAKSGKNLPIQRDIELNWNGEAYEYSNSNYFPINGQXFN DVSYPV--- ---VTCGGCETCSYATGKCEPDSSLCNDNNICT...*fricqiw*kssnskryrvklewrsi*i**fkllpn*rtxfq *cklss--- ---VTCGGCETCSYATGKCEPDSSLCNDNNICTIDICVHEGILDGLPQGNCSNTP

  8. 47 CFR 80.876 - VHF radiotelephone antenna system.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false VHF radiotelephone antenna system. 80.876... to Subpart W § 80.876 VHF radiotelephone antenna system. A vertically polarized nondirectional antenna must be provided for VHF radiotelephone installations. The construction and installation of...

  9. CMOS VHF transconductance-C lowpass filter

    NARCIS (Netherlands)

    Nauta, B.

    1990-01-01

    Experimental results of a VHF CMOS transconductance-C lowpass filter are described. The filter is built with transconductors as published earlier. The cutoff frequency can be tuned from 22 to 98 MHz and the measured filter response is very close to the ideal response

  10. 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.

  11. Survey of man-made electrical noise affecting radio broadcasting

    Science.gov (United States)

    Bisignani, W. T.; Garner, W. B.

    1969-01-01

    Survey, consisting of limited noise measurements, was made to augment and verify existing data at HF and VHF and to obtain basic data at UHF. Exact frequencies were determined by the absence of intentionally generated signals around three selected frequencies.

  12. 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

  13. 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....

  14. 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...

  15. Dicty_cDB: VHF229 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Sequences producing significant alignments: (bits) Value VHF229 (VHF229Q) /CSM/VH/VHF2-B/VHF229Q.Seq.d/ 68 ...v41i08, 3' ... 54 7e-09 2 dna update 2008.10.24 Homology vs Protein Score E Sequences producing significant alignments: (bits) Value.../CH/CHD6-A/CHD613Q.Seq.d/ 32 2.8 own update 2002.12.27 Homology vs DNA Score E Sequences producing significant alignments: (bits) Val...ue N ( BJ439713 ) Dictyostelium discoideum cDNA clone:dd

  16. 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.

  17. 47 CFR 80.467 - Duplication of VHF service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Duplication of VHF service. 80.467 Section 80... STATIONS IN THE MARITIME SERVICES Public Coast Stations Use of Telephony § 80.467 Duplication of VHF service. No duplication of service areas as determined by subpart P of this part will be permitted...

  18. 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...

  19. 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.

  20. 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...

  1. 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...

  2. 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.

  3. An Advanced VHF/UHF Short Range, Groundwave Propagation Model for Paths With Near-Earth Antennas

    Science.gov (United States)

    2006-11-01

    Jonathan Zenneck who developed a novel approach to solving Maxwell’s equations: a wavelike solution that was consi stent with the boundary conditions...free electric charge to produce the circulating currents that create Joule heating (“i2R”) losses in the earth (assumed to be a perfect dielectric with

  4. 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.

  5. Development Of VHF (240-270 MHz) Antennas For SoOp (Signal Of Opportunity) Receiver For 6u Cubesat Platforms

    Science.gov (United States)

    Joseph, A. T.; Deshpande, M.; O'Neill, P. E.; Miles, L.

    2016-01-01

    The main goal of this research is to design, fabricate, and test deployable VHF antennas for 6U Cubesat platforms to enable validation of root zone soil moisture (RZSM) estimation algorithms for signal of opportunity (SoOp) remote sensing over the 240-270 MHz frequency band. The proposed work provides a strong foundation for establishing a technology development path for maturing a truly global direct surface soil moisture (SM) and RZSM measurement system (Figure 1) over a variety of land covers with limited density restrictions. In SoOp methodology, signals transmitted by already existing transmitters (known as transmitters of opportunity, in this case the Military Satellite Communication (MilSatCom) System's UHF Follow-On program) are utilized to measure properties of reflecting targets by recording reflected signals using a simple passive microwave receiver.

  6. Electric Field Change and VHF Radiation during Lightning Initiation

    Science.gov (United States)

    Marshall, T. C.; Karunarathne, S.; Bandara, S. A.; Karunarathne, N. D.; Siedlecki, R.; Stolzenburg, M.

    2016-12-01

    Recent studies of lightning initiation [e.g., Marshall et al., JGR 2014; Marshall et al., AGU 2015] have shown that an initial electric field change (IEC) occurs for about 1 ms before the first initial breakdown (IB) pulse in most (and perhaps all) lightning flashes. The same studies indicate that the IEC itself begins after an event that radiates strongly in the VHF radio band; this event seems to be the real lightning initiation event [e.g., Rison et al., Nature Communications 2016]. During the summer of 2016 we used an array of E-change sensors and VHF sensors located in north Mississippi to obtain correlated data on the VHF lightning initiation event, the IEC, and the IB pulses of nearby lightning flashes. In this presentation we show examples of lightning initiation events and their subsequent IECs at multiple sensors. In addition, we show examples of the VHF radiation associated with IB pulses.

  7. 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

  8. Ultimate VHF Broadband Interferometer Zen KAWASAKI and Manabu AKITA

    Science.gov (United States)

    Kawasaki, Z.; Akita, M.

    2013-12-01

    Lightning Research Group of Osaka University (LRGOU) has been developing an interferometer for thunderstorm monitoring during these two decades. When LRGOU initiated this project, many related scientists claimed that LRGOU's system was a time of arrival and it must be a sophisticated TOA system. However the key technology of the system were broad band and digital data processing, and it is named the VHF broad band digital interferometer (BDITF), because the phase difference of Fourier components played the very important role. Then the BDITF finally has been realized as a quasi-real time lightning monitoring system, and LRGOU has been operating their BDITFs around Osaka area. Since the BDITF captures the VHF impulses associated with lightning discharges by amplitude triggering, it occasionally misses one of the bi-directional leader progressions because of relatively small amplitude VHF impulses mainly emitted by positive leader tips. All of high density of VHF pulses associated with recoil leaders may not be recorded. Then the ordinary BDITF is able to be accepted as the practical operational system, but from the aspect of science it has been sioriously expected to be improved its performance. To overcome the difficulty New Mexico Institute of Mining and Technology (NMIMT) and LRGOU have started the joint project, and a continuous recording system for digital signals is adopted [M. Stock et al, and M Akita et al,]. The field campaigns have been conducting in New Mexico and in Japan, and successful observations are accomplished. The algorithm to identify individual VHF pulses associated with lightning discharges from back ground noise and/or artificial noise, the dispersion of phase differences for all Fourier components is examined. In case by of small dispersion it is concluded that analyzed VHF pulse has high possibility to be emitted by lightning discharges. This interpretation means that the recorded VHF pulse shape might maintain without deformation during

  9. 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.

  10. 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.

  11. Modern HF Communications.

    Science.gov (United States)

    1983-05-01

    vertically directed pulRe,’ radar , measures the delay time of the reflected siqnals in the frequency ranqe 1-20 MHz. This delay time is converted to a...qensitive and sophisticated iH or UHF- radars which detect weak reflections from plasma irregularit ies. There are ooil a few such installations in operation...terms of a few measurable parameeprs, so that the raytracing through the simplified model ionosphere yields realistic signal characteristics, for

  12. 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.

  13. Low level range coverage performance prediction for VHF radar

    Science.gov (United States)

    Kuschel, H.

    1989-09-01

    A VHF radar frequencies the range coverage is not strictly limited by the quasi-optical horizon like at microwave radar frequencies but is extended due to diffraction propagation. This effect, here called beyond-the-horizon (BTH) detection capability is strongly dependent on the propagation path and thus on the terrain structure. The availability of digital terrain maps gives way to the use of computerized methods for the prediction of radar range coverage in real environment. In combination with wave propagation models suitable for diffraction at terrain structures, digital terrain data can even be used for the prediction of BTH target detectability at VHF radar. Here the digital landmass system (DLSS) terrain database was used in combination with a multiple-knife-edge diffraction model to predict the diffraction attenuation between the radar and the potential target positions, especially beyond the optical horizon. The propagation paths extracted from the database are modeled as a sequence of diffraction screens suited for the application of a Fresnel-Kirchhoff algorithm yielding the knife-edge-diffraction attenuation. This terrain related propagation model was verified by a large number of measurements at different frequencies. Implemented in a fast computer system, this prediction model can be used for mission planning of air operations. Considering hostile VHF radar coverage and terrain condition for flight path optimization or, on the other hand it can assist in siting mobile radars for gap filling according to the actual threat situation. Calculations of the diffraction propagation using the prediction model, yield range coverage patterns in real terrain situations, allowing to quantify the BTH detection advantage of VHF radar compared to microwave radar. An experimental large wavelength radar LARA (VHF) built flying targets beyond the close horizon. Here, especially the detection of hiding helicopters by exploiting diffractive wave propagation was examined

  14. ExtraHF survey

    DEFF Research Database (Denmark)

    Piepoli, Massimo F; Binno, Simone; Corrà, Ugo

    2015-01-01

    AIMS: In heart failure (HF), exercise training programmes (ETPs) are a well-recognized intervention to improve symptoms, but are still poorly implemented. The Heart Failure Association promoted a survey to investigate whether and how cardiac centres in Europe are using ETPs in their HF patients...... of evidence on safety or benefit was cited. When implemented, an ETP was proposed to all HF patients in only 55% of the centres, with restriction according to severity or aetiology. CONCLUSIONS: With respect to previous surveys, there is evidence of increased availability of ETPs in HF in Europe, although too...

  15. Automatic tuning of quality factors for VHF CMOS filters

    NARCIS (Netherlands)

    Nauta, Bram; Seevinck, Evert

    1990-01-01

    A VHF transconductance-C filter technique with automatic tuning of the quality factors and the cutoff frequency, based on a voltage controlled oscillator (VCO), is presented. The Q-tuning circuit is very simple and contains no signal carrying nodes, resulting in a well-controlled Q up to very high f

  16. First 100 ms of HF modification at Tromso, Norway

    Science.gov (United States)

    Djuth, F. T.; Isham, B.; Rietveld, M. T.; Hagfors, T.; La Hoz, C.

    Experiments were performed with the high-power high-frequency HF facility at Troms o Norway to test theoretical predictions for the excitation of ion and Langmuir oscillations in the ionosphere The principal diagnostic of wave-plasma interactions was the VHF radar at the European Incoherent Scatter EISCAT facility High resolution radar techniques were used to monitor the temporal development of the ion and Langmuir oscillations HF pulses 100 ms in duration were periodically transmitted into a smooth background F region plasma Measurements of the radar backscatter spectra show that all key spectral features predicted by strong Langmuir turbulence SLT theory modified Zakharov model are simultaneously present in the plasma and that their evolution is in agreement with theoretical expectations However several new features have been observed that cannot be anticipated by current theory because of limitations in the electric field strength within the simulations The experimental results reinforce the notion that new theoretical developments are needed to accommodate the large HF electric fields produced at Troms o and HAARP Gakona Alaska and to treat the electron acceleration process in a self-consistent fashion The F region response to two HF effective radiated power levels sim 58 MW and sim 125 MW was investigated at Troms o These ERP values include absorptive losses resulting from the sunlit D region In general the results at 58 MW ERP and 125 MW ERP are consistent with many of the SLT

  17. 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.

  18. A classification of spectral populations observed in HF radar backscatter from the E region auroral electrojets

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations are identified with type I and type II spectral classes, and hence, are thought to be generated by the two-stream and gradient drift instabilities, respectively. The remaining three populations occur over a range of velocities which can greatly exceed the ion acoustic speed, the usual limiting velocity in VHF radar observations of the E region. The generation of these spectral populations is discussed in terms of electron density gradients in the electrojet region and recent non-linear theories of E region irregularity generation.

    Key words. Ionosphere (ionospheric irregularities

  19. 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.

  20. Refraction of VHF radio waves in artificial plasma formations

    Science.gov (United States)

    Kashirin, A. I.; Kliueva, N. M.; Mikhailik, P. P.; Chkalov, V. G.

    1991-09-01

    The defocusing refraction of VHF waves during the radio occultation of artificial plasma clouds in the ionosphere is calculated in the framework of the geometrical-optics approximation. The possibility of determining the main cloud parameters from characteristic power variations of the received radio waves in the case of a monotonic change in the sighting parameter during the experiment is demonstrated. Results of a rocket experiment implementing this method are presented.

  1. Measurements of ionospheric effects on wideband signals at VHF

    Energy Technology Data Exchange (ETDEWEB)

    Fitzgerald, T.J.

    1998-08-17

    Radars operating at very high frequency (VHF) have enhanced foliage and ground penetration compared to radars operated at higher frequencies. For example, VHF systems operated from airplanes have been used as synthetic aperture radars (SAR); a satellite-borne VHF SAR would have considerable utility. In order to operate with high resolution it would have to use both a large relative bandwidth and a large aperture. A satellite-borne radar would likely have to operate at altitudes above the maximum density of the ionosphere; the presence of the ionosphere in the propagation path of the radar will cause a deterioration of the performance because of dispersion over the bandwidth. The author presents measurements of the effects of the ionosphere on radar signals propagated from a source on the surface of the Earth and received by instruments on the FORTE satellite at altitudes of 800 km. The author employs signals with a 90 MHz bandwidth centered at 240 MHz with a continuous digital recording period of 0.6 s.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. Ergonomics action research II: a framework for integrating HF into work system design.

    Science.gov (United States)

    Neumann, W P; Village, J

    2012-01-01

    This paper presents a conceptual framework that can support efforts to integrate human factors (HF) into the work system design process, where improved and cost-effective application of HF is possible. The framework advocates strategies of broad stakeholder participation, linking of performance and health goals, and process focussed change tools that can help practitioners engage in improvements to embed HF into a firm's work system design process. Recommended tools include business process mapping of the design process, implementing design criteria, using cognitive mapping to connect to managers' strategic goals, tactical use of training and adopting virtual HF (VHF) tools to support the integration effort. Consistent with organisational change research, the framework provides guidance but does not suggest a strict set of steps. This allows more adaptability for the practitioner who must navigate within a particular organisational context to secure support for embedding HF into the design process for improved operator wellbeing and system performance. There has been little scientific literature about how a practitioner might integrate HF into a company's work system design process. This paper proposes a framework for this effort by presenting a coherent conceptual framework, process tools, design tools and procedural advice that can be adapted for a target organisation.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

    Directory of Open Access Journals (Sweden)

    N. F. Blagoveshchenskaya

    2009-01-01

    Full Text Available Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency fH was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ. The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the London-Tromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland, the European Incoherent Scatter (EISCAT UHF radar at Tromsø and the Tromsø ionosonde (dynasonde. The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization.

  12. A D-region conductivity model from EISCAT VHF measurements

    Directory of Open Access Journals (Sweden)

    K. Schlegel

    Full Text Available An easy-to-use model to evaluate conductivities at high and middle latitudes in the height range 70–100 km is presented. It is based on electron density profiles obtained with the EISCAT VHF radar during 11 years and on the neutral atmospheric model MSIS95. The model uses solar zenith angle, geomagnetic activity and season as input parameters. It was mainly constructed to study the properties of Schumann resonances that depend on such conductivity profiles.

    Key words. Meteorology and atmospheric dynamics (middle atmospheric dynamics – Ionosphere (modeling and forecasting; ionosphere-atmosphere interaction

  13. Statistical characteristics of PMWE observations by the EISCAT VHF radar

    Directory of Open Access Journals (Sweden)

    I. Strelnikova

    2013-02-01

    Full Text Available In the present paper ~ 32.5 h of EISCAT VHF PMWE observations were analyzed with focus on spectral properties like spectral width, doppler shift and spectral shape. Examples from two days of observations with weak and strong polar mesosphere winter echo (PMWE signals are presented and discussed in detail. These examples reveal a large variability from one case to the other. That is, some features like an observed change of vertical wind direction and spectral broadening can be very prominent in one case, but unnoticeable in the other case. However, for all observations a change of spectral shape inside the layer relative to the incoherent background is noticed.

  14. Very Compact and Broadband Active Antenna for VHF Band Applications

    Directory of Open Access Journals (Sweden)

    Y. Taachouche

    2012-01-01

    Full Text Available An active receiving antenna with small size consisting of a monopole loaded with a transistor bipolar is presented in this paper. A transistor is used in order to miniaturize the receiving active antenna size in VHF band. The vertical size of the structure is equal to λ/175, where λ is the wavelength at the lower frequency of the bandwidth. Despite the very small size of the antenna, the frequency bandwidth is very wide and the gain is suitable for FM application with sensitive receivers.

  15. STRUCTURAL PROPERTIES INVESTIGATION ON MICROCRYSTALLINE SILICON FILMS DEPOSITED WITH VHF-PECVD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    H.D. Yang

    2005-01-01

    Raman scattering spectroscopy and scanning electron microscopy (SEM) techniques were used to determine the structural properties of two typical series of microcrystalline silicon(μc-Si:H) films deposited at different VHF plasma power and different working gas pressure by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. Raman spectra measurements show that both crystalline volume fraction Xc and average grain size d of μc-Si: H films are strongly affected by the two deposition conditions and are more sensitive to working gas pressure than VHF plasma power. SEM characterizations have further confirmed that VHF plasma power and working gas pressure could clearly enhance the surface roughness of μc-Si: H films ascribing to polymerization reactions, which is also more sensitive to working gas pressure than VHF plasma power.

  16. Frederiksberg HF kursus

    DEFF Research Database (Denmark)

    Lindstrøm, Maria Duclos

    2008-01-01

    Notatet bygger på et interviewmateriale med dimitterede HF-kursister 3 måneder efter endt eksamen. Notatet undersøger dels, hvad der har hjulpet til at gennemføre, dels hvad der har været negativt og vanskeligt ved uddannelsen. Endvidere belyser notatet hvad kursisterne oplever at tage med fra de...

  17. 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.

  18. 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.

  19. 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.

  20. Design of ultra broadband VHF/UHF antenna based on varied curve combination method%基于变曲线组合方法的超宽带VHF/UHF天线设计

    Institute of Scientific and Technical Information of China (English)

    魏福显; 后骥

    2014-01-01

    With the continuous extension of radio monitoring mission,the monitoring antennas are confronted with the chal-lenge of ultra wideband and miniaturization. A varied curve combination method is presented in this paper to design the anten-nas by the aid of the method of moments. An ultra wideband dipole antenna covering 80~3 000 MHz was designed. The effective-ness of the proposed method was confirmed by the simulated data and measured data.%随着无线电监测业务的不断扩展,监测天线面临着超宽带化、小型化等挑战。提出一种变曲线组合方法,并结合矩量法进行天线设计,设计出一款可覆盖80~3000 MHz的超宽带偶极子全向天线,基于仿真数据和实测数据的结果验证了该设计方法的有效性。

  1. 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.

  2. 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...

  3. 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...

  4. Low-loss NiZnCo ferrite processed at low sintering temperature with matching permeability and permittivity for miniaturization of VHF-UHF antennas

    Science.gov (United States)

    Zheng, Zongliang; Feng, Quanyuan; Xiang, Qianyin; Di, Zhixiong; Harris, Vincent G.

    2017-02-01

    Spinel ferrites of a nominal composition of Ni0.5Zn0.3Co0.2Fe2O4 (NiZnCo) with various B2O3-Bi2O3-SiO2-ZnO (BBSZ) glass additions were successfully synthesized at a relatively low temperature of 930 °C for their potential applications as magneto-dielectric antenna substrate materials. Measurements of magnetic and dielectric properties show that, with an increasing content of BBSZ from 0 to 2 wt. %, the permeability μ' at low frequencies was increased from ˜4.7 to ˜8.9, whereas the permittivity ɛ' was improved from ˜5.9 to ˜12.5. These tunable permeability and permittivity were proved to be closely related to the grain size and density, based on the magnetic circuit model and effective medium theory. Importantly, the sample with 0.5 wt. % addition demonstrated the optimal magneto-dielectric performance with nearly equivalent values of μ' and ɛ', which yields a large miniaturization factor of ˜6.5 and the normalized impedance of ˜1 over the frequency range of 10 MHz-1 GHz. Moreover, this sample exhibits low loss characteristics over a wide frequency range, where the dielectric loss tan δɛ is in the order of 10-3 and the magnetic loss tan δμ is less than 0.15. These properties make the ferrite material a promising candidate for miniaturized antennas with good impedance matched to free space and open a great potential for low-temperature co-fired ceramic applications toward the practical fabrication and high integration of the antennas.

  5. 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.

  6. DISCOURSE OF VHF COMMUNICATION AT SEA AND THE INTERCULTURAL ASPECT

    Directory of Open Access Journals (Sweden)

    Milena Dževerdanović-Pejović

    2013-12-01

    Full Text Available Discourse analysis of real examples of internal and external communication at sea represents a real challenge for linguists. Research in this field is at its very beginning and was partially presented in the final report of the MARCOM project (1999. The main reason for this is the scarcity of the available VHF material and on-board verbal recordings. This paper explored to what extent the rules for radio conversation are applied in the segments of real verbal communication between ships at sea, especially with regard to application of the Standard Marine Communication Phrases (SMCP, set by the International Maritime Organization (IMO in 2001. Using knowledge of conversation analysis as a peculiar branch of discourse analysis and intercultural communication theories dealing with multi-cultural crewing issues, the special emphasis was given to the formal/informal, official/unofficial and standardized/non-standardized discourse dichotomies.

  7. 75 FR 57947 - Auction of VHF Commercial Television Station Construction Permits Scheduled for February 15, 2011...

    Science.gov (United States)

    2010-09-23

    ...This document announces the auction of certain VHF construction permits scheduled to commence on February 15, 2011 (Auction 90). This document also seeks comment on competitive bidding procedures for Auction 90.

  8. 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。

  9. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  10. 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.

  11. 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.

  12. Stochastic relation between anomalous propagation in the line-of-sight VHF radio band and occurrences of earthquakes

    Directory of Open Access Journals (Sweden)

    K. Motojima

    2013-11-01

    Full Text Available This paper was intended to find out any relation between anomalous line-of-sight propagation on the VHF band and occurrences of earthquakes near the VHF propagation paths. The television and FM radio broadcasting waves on the VHF band were monitored continuously over the long term. For that purpose, a multidirectional VHF band monitoring system was established and utilized. Anomalous line-of-sight propagation on the VHF band was distinguished from the monitored wave by using a statistical analysis. After the stochastic consideration, it was found out that earthquakes associated with anomalous propagation were characterized by magnitude of earthquakes M ≥ 4.5, and distances from epicenters L ≤ 75 km. The anomalous propagation was monitored on the VHF band a few days earlier the associated earthquakes occurred. Moreover, the anomaly appeared on multidirectional propagation paths simultaneously. The anomaly on the line-of-sight propagation indicates possibility of narrow focusing the area of epicenter of earthquake.

  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. HF Interference, Procedures and Tools (Interferences HF, procedures et outils)

    Science.gov (United States)

    2007-06-01

    such sources. The existing HF background noise possibly may be increased via ground wave and/or sky wave propagation. Increase of the existing HF...télécommunications filaires à large bande. Les télécommunications via le réseau électrique courant, dites PowerLine Communications (PLT ou PLC) et diverses...cumulative de nombreuses sources de même type. Le bruit de fond HF existant risque d’être augmenté par propagation de l’onde terrestre et/ou aérienne

  17. 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....

  18. Large ionospheric disturbances produced by the HAARP HF facility

    Science.gov (United States)

    Bernhardt, Paul A.; Siefring, Carl L.; Briczinski, Stanley J.; McCarrick, Mike; Michell, Robert G.

    2016-07-01

    The enormous transmitter power, fully programmable antenna array, and agile frequency generation of the High Frequency Active Auroral Research Program (HAARP) facility in Alaska have allowed the production of unprecedented disturbances in the ionosphere. Using both pencil beams and conical (or twisted) beam transmissions, artificial ionization clouds have been generated near the second, third, fourth, and sixth harmonics of the electron gyrofrequency. The conical beam has been used to sustain these clouds for up to 5 h as opposed to less than 30 min durations produced using pencil beams. The largest density plasma clouds have been produced at the highest harmonic transmissions. Satellite radio transmissions at 253 MHz from the National Research Laboratory TACSat4 communications experiment have been severely disturbed by propagating through artificial plasma regions. The scintillation levels for UHF waves passing through artificial ionization clouds from HAARP are typically 16 dB. This is much larger than previously reported scintillations at other HF facilities which have been limited to 3 dB or less. The goals of future HAARP experiments should be to build on these discoveries to sustain plasma densities larger than that of the background ionosphere for use as ionospheric reflectors of radio signals.

  19. 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。

  20. 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.

  1. Letter to the Editor: Complete maps of the aspect sensitivity of VHF atmospheric radar echoes

    Directory of Open Access Journals (Sweden)

    S. Fukao

    Full Text Available Using the MU radar at Shigaraki, Japan (34.85°N, 136.10°E, we measure the power distribution pattern of VHF radar echoes from the mid-troposphere. The large number of radar beam-pointing directions (320 allows the mapping of echo power from 0° to 40° from zenith, and also the dependence on azimuth, which has not been achieved before at VHF wavelengths. The results show how vertical shear of the horizontal wind is associated with a definite skewing of the VHF echo power distribution, for beam angles as far as 30° or more from zenith, so that aspect sensitivity cannot be assumed negligible at any beam-pointing angle that most existing VHF radars are able to use. Consequently, the use of VHF echo power to calculate intensity of atmospheric turbulence, which assumes only isotropic backscatter at large beam zenith angles, will sometimes not be valid.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence; instruments and techniques

  2. A New Range Sidelobe Suppression Technique for Randomly Intermittent Spectra HF Radar Signal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dong-po; LIU Xing-zhao

    2005-01-01

    The randomly intermittent spectra (RIS) signal is employed to combat spectrum congestion in radar and other radio services to evade the external interferences in high-frequency (HF) and ultrahigh-frequency (UHF)bands. However, the spectra discontinuity of the signal gets rise to high range sidelobes when matching the refleeted echo, which is much more difficult for targets detection. So it is indispensable to investigate the technique for sidelobes suppression of the range profile when RIS signal is utilized, This paper introduced a new processing technique based on time domain filtering to lower the range sidelobes. A robust and effetive algorithm is adopted to solve the coefficients of the filter, and the restriction on the desired response of the filter is derived. The simulation results show that the peak range sidelobe can be reduced to -27 dB from -9.5 dB while the frequency band span (FBS) is 200 kHz.

  3. 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%.

  4. Marburg Hemorrhagic Fever (Marburg HF)

    Science.gov (United States)

    ... CDC Cancel Submit Search The CDC Marburg hemorrhagic fever (Marburg HF) Note: Javascript is disabled or is ... first recognized in 1967, when outbreaks of hemorrhagic fever occurred simultaneously in laboratories in Marburg and Frankfurt, ...

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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)

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. PENUMBUHAN LAPISAN TIPIS SILIKON MIKROKRISTAL TERHIDROGENASI DENGAN TEKNIK HWC-VHF-PECVD

    Directory of Open Access Journals (Sweden)

    Ida Usman

    2012-02-01

    Full Text Available Telah dikembangkan teknik HWC-VHF-PECVD (Hot Wire Cell Very High Frequency Plasma Enhanced Chemical Vapor Deposition untuk menumbuhkan lapisan tipis silikon mikrokristal terhidrogenasi (mc-Si:H. Dari hasil penumbuhan lapisan tipis yang dilakukan, teknik HWC-VHF-PECVD memperlihatkan laju deposisi yang lebih tinggi dibandingkan laju deposisi lapisan tipis yang diperoleh dari teknik PECVD maupun teknik VHF-PECVD konvensional. Berdasarkan hasil pengukuran XRD dan SEM, lapisan yang diperoleh pada temperatur filamen yang rendah masih berstruktur amorf. Indikasi yang mengarah pada pembentukan lapisan tipis berstruktur mikrokristalin mulai terlihat pada temperatur filamen ≥ 500oC, dimana puncak-puncak di fraksi spektrum XRD untuk orientasi kristalin tertentu mulai terbentu, sejalan dengan pembentukan butiran-butiran kristalin dari hasil foto SEM permukaan lapisan-lapisan tersebut.

  19. Anomalous propagation of VHF radiowaves behind the horizon in the seismic region

    Science.gov (United States)

    Sorokin, V. M.; Yashchenko, A. K.

    2016-11-01

    A theory of electromagnetic radiation generation by random electric discharges in the troposphere and VHF radiowave scattering by these discharges has been developed. The discharge model, which makes it possible to calculate the spatiotemporal distribution of the discharge channel conductivity depending on the electric current value in this discharge, has been obtained. The electromagnetic radiation spectrum in the troposphere occupied by random discharges has been calculated. VHF electromagnetic wave scattering by random electric discharges in the troposphere has been considered. Equations have been derived, and the method for calculating the average value of the electromagnetic wave field scattered by random discharges has been developed. The calculations indicated that the scattered wave field amplitude is much larger than the diffraction wave field amplitude behind the horizon. The theoretical results agree with the observations of the electromagnetic radiation and VHF transmitter signals behind the horizon relative to the earthquake epicenter during the earthquake preparation.

  20. Investigation of over-horizon VHF radio signals associated with earthquakes

    Directory of Open Access Journals (Sweden)

    Y. Fukumoto

    2001-01-01

    Full Text Available This paper presents the preliminary results on the possible reception of over-horizon VHF radio signals from a FM (frequency modulation transmitter during abnormal situations (probably in close association with earthquakes. The transmitter is FM Sendai (frequency = 77.1 MHz and the receiving station is our university (UEC at Chofu, Tokyo, with the transmitter-receiver distance being about 310 km. We first show a typical example of the reception of over-horizon VHF signals in which we present the amplitude behavior, azimuthal and incident angle estimation, etc. Then, we study the correlation between a signal anomaly and an earthquake and it seems that the over-horizon VHF signals observed are probably associated with earthquakes, observed about 7 to 0 days before an earthquake. The direction finding measurements have indicated that such signals are due to favorable tropospheric (but not ionospheric conditions attributed to the effects of earthquakes.

  1. Hf Transition Probabilities and Abundances

    CERN Document Server

    Lawler, J E; Labby, Z E; Sneden, C; Cowan, J J; Ivans, I I

    2006-01-01

    Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 150 lines of Hf II. Approximately half of these new transition probabilities overlap with recent independent measurements using a similar approach. The two sets of measurements are found to be in good agreement for measurements in common. Our new laboratory data are applied to refine the hafnium photospheric solar abundance and to determine hafnium abundances in 10 metal-poor giant stars with enhanced r-process abundances. For the Sun we derive log epsilon (Hf) = 0.88 +/- 0.08 from four lines; the uncertainty is dominated by the weakness of the lines and their blending by other spectral features. Within the uncertainties of our analysis, the r-process-rich stars possess constant Hf/La and Hf/Eu abundance ratios, log epsilon (Hf...

  2. Gradual approach to realize lightning monitoring from space by means of VHF observations

    Science.gov (United States)

    Morimoto, T.; Kikuchi, H.; Ushio, T.; Kawasaki, Z.

    2010-12-01

    Lightning Research Group of Osaka University (LRG-OU) has been developing VHF Broadband Digital Interferometer (DITF) to image precise lightning channels and monitor lightning activity widely. DITF is an equipment to locate sources of impulsive VHF radiation based on the digital interferometric technique. In other words, DITF is a system to visualize lightning channel by VHF radio observations. The feature of DITF is its ultra-wide bandwidth (from 25 MHz to 100 MHz) and implicit redundancy for the direction-of-arrival (DOA) estimation. LRG-OU considers an application of the broadband DITF to the spaceborne measurement system because its fairly high resolutions and the compactness of the system are great advantages to be the space-borne one. To realize space-borne DITF, LRG-OU intends to have gradual approach for the development. As their first step, a VHF sensor on Maido-1 satellite is proposed to examine the feasibility of receiving VHF lightning impulses in space. Maido-1 is a small satellite manufactured by factory members of SOHLA (Space Oriented Higashi-Osaka Leading Associate). The SOHLA project represents a technology transfer program to expand the range of the space development community in Japan. The objective is to get SMEs (Small and Medium sized manufacturing Enterprises) involved in small space projects and new space technologies. Under the cooperative agreement, JAXA (Japan Aerospace Exploration Agency) intends to contribute to socio-economic development by returning its R&D results to the society, and SOHLA tries to revitalize the local economy through the commercialization of versatile small satellites. Maido-1 is in sun-synchronous polar orbit at an altitude of 660 kilometers. The VHF sensor comprises a single pair of an antenna, a band-pass filter with a pass band of 30-100MHz, an amplifier with a gain of 45dB and an analog-to-digital converter with a sampling rate of 200MS/s and 8-bit resolution to record broadband VHF signals. The 100 waveforms

  3. Analysis of Terminal Velocity and VHF Backscatter of Precipitation Particles Using Chung-Li VHF Radar Combined with Ground-Based Disdrometer

    Directory of Open Access Journals (Sweden)

    Ching-Lun Su and Yen-Hsyang Chu

    2007-01-01

    Full Text Available The backscatter from precipitation particles observed by the vertically pointed antenna beam of the Chung-Li VHF radar and the drop size distributions measured by a ground-based disdrometer co-located at the radar site are analyzed and studied in this article. We find that the disdrometermeasured drop size distribution can be well approximated to a Gamma distribution. On the basis of this property and a power law approximation to the fallspeed-diameter relation VD = ADB, we derive the theoretical relation between terminal velocity VD and range-corrected VHF backscatter P of the precipitation particles. We find that the VD - P relation follows a power law in the form of VD = _ where _ _ both the functions of the precipitation parameters. Chu et al. (1999 first found that the relation between _ _ be empirically approximated to an exponential form of _ _ where _ a function of B and _ a factor associated with precipitation. In this article, under the assumptions of the Gamma distribution of the drop size distribution and the power-law relation between VD and D, we theoretically show that the analytical relation between _ _ follows an exponential form of _ _ where _ a function of the drop size distribution. The experimental results obtained by the Chung-Li VHF radar combined with the ground-based disdrometer measurements validate the exponential approximation to the _ _ The uses of the _ _ for the investigations of the rainfall rate and properties of drop size distribution are presented and discussed.

  4. 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...

  5. 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...

  6. A VHF Class E DC-DC Converter with Self-Oscillating Gate Driver

    DEFF Research Database (Denmark)

    Andersen, Toke Meyer; Christensen, Søren K.; Knott, Arnold

    2011-01-01

    This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz − 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver, is...

  7. An analysis on the mid-latitude scintillation and coherence frequency bandwidth using transionospheric VHF signals

    Energy Technology Data Exchange (ETDEWEB)

    Juang, Zhen [Los Alamos National Laboratory; Roussel-dupre, Robert [Los Alamos National Laboratory

    2008-01-01

    An analysis was perfonned on the mid-latitude scintillation and coherence frequency bandwidth (Fcoh) using transionospheric VHF signal data. The data include 1062 events spanning from November 1997 to June 2002. Each event records FORTE satellite received VHF signals from LAPP located at Los Alamos, New Mexico. Fcohs were derived to study scintillation characteristics on diurnal and seasonal variations, as well as changes due to solar and geomagnetic activities. Comparisons to the VHFIUHF coherence frequency bandwidth studies previously reported at equatorial and mid-latitude regions are made using a 4th power frequency dependence relationship. Furthennore, a wideband ionospheric scintillation model, WBMOD, was used to estimate Fcohs and compared with our VHF Fcoh values. Our analysis indicates mid-latitude scintillation characteristics that are not previously revealed. At the VHF bottom frequency range (3035 MHz), distinguished smaller Fcohs are found in time period from sunset to midnight, in wann season from May to August, and in low solar activity years. The effects of geomagnetic storm activity on Fcoh are characterized by a sudden transition at a Kp index of 50-60. Comparisons with median Fcohs estimated from other studies validated our VHF Fcohs for daytime while an order of magnitude larger Fcohs are found for nighttime, implying a time-dependent issue in applying the 4th order power relationship. Furthermore, comparisons with WBMOD-estimated Fcohs indicated generally matched median scintillation level estimates while differences do exist for those events undergoing high geomagnetic stonn activity which may imply underestimates of scintillation level by the WBMOD in the mid-latitude regions.

  8. Testing VHF/GPS collar design and safety in the study of free-roaming horses.

    Directory of Open Access Journals (Sweden)

    Gail H Collins

    Full Text Available Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roaming horse behavior and habitat use and to aid in making informed management decisions. Global positioning system (GPS and very high frequency (VHF radio collars can be used to provide high spatial and temporal resolution information for detecting free-roaming horse movement. GPS and VHF collars are a common tool used in wildlife management, but have rarely been used for free-roaming horse research and monitoring in the United States. The purpose of this study was to evaluate the design, safety, and detachment device on GPS/VHF collars used to collect free-roaming horse location and movement data. Between 2009 and 2010, 28 domestic and feral horses were marked with commercial and custom designed VHF/GPS collars. Individual horses were evaluated for damage caused by the collar placement, and following initial observations, collar design was modified to reduce the potential for injury. After collar modifications, which included the addition of collar length adjustments to both sides of the collar allowing for better alignment of collar and neck shapes, adding foam padding to the custom collars to replicate the commercial collar foam padding, and repositioning the detachment device to reduce wear along the jowl, we observed little to no evidence of collar wear on horses. Neither custom-built nor commercial collars caused injury to study horses, however, most of the custom-built collars failed to collect data. During the evaluation of collar detachment devices, we had an 89% success rate of collar devices detaching correctly. This study showed that free-roaming horses can be safely marked with GPS and/or VHF collars with minimal risk of injury, and that these collars can be a useful tool for monitoring horses without creating a risk to horse health and wellness.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    N. F. Arnold

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

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

  2. Plasma modifications induced by an X-mode HF heater wave in the high latitude F region of the ionosphere

    Science.gov (United States)

    Blagoveshchenskaya, N. F.; Borisova, T. D.; Yeoman, T. K.; Rietveld, M. T.; Häggström, I.; Ivanova, I. M.

    2013-12-01

    We presented experimental results of strong plasma modifications induced by X-mode powerful HF radio waves injected towards the magnetic zenith into the high latitude F region of the ionosphere. The experiments were conducted in 2009-2011 using the EISCAT Heating facility, UHF incoherent scatter radar and the EISCAT ionosonde at Tromsø, Norway; and the CUTLASS SuperDARN HF coherent radar at Hankasalmi, Finland. The results showed that the X-mode HF pump wave can generate strong small-scale artificial field aligned irregularities (AFAIs) in the F region of the high-latitude ionosphere. These irregularities, with spatial scales across the geomagnetic field of the order of 9-15 m, were excited when the heater frequency (fH) was above the ordinary-mode critical frequency (foF2) by 0.1-1.2 MHz. It was found that the X-mode AFAIs appeared between 10 s and 4 min after the heater is turned on. Their decay time varied over a wide range between 3 min and 30 min. The excitation of X-mode AFAIs was accompanied by electron temperature (Te) enhancements and an increase in the electron density (Ne) depending on the effective radiated power (ERP). Under ERPs of about 75-180 MW the Te enhances up to 50% above the background level and an increase in Ne of up to 30% were observed. Dramatic changes in the Te and Ne behavior occurred at effective radiated powers of about 370-840 MW, when the Ne and Te values increased up to 100% above the background ones. It was found that AFAIs, Ne and Te enhancements occurred, when the extraordinary-mode critical frequency (fxF2) lied in the frequency range fH-fce/2≤fxF2≤fH+fce/2, where fce is the electron gyrofrequency. The strong Ne enhancements were observed only in the magnetic field-aligned direction in a wide altitude range up to the upper limit of the UHF radar measurements. In addition, the maximum value of Ne is about 50 km higher than the Te enhancement peak. Such electron density enhancements (artificial ducts) cannot be explained by

  3. Environmentally friendly HF (DF) lasers

    Science.gov (United States)

    Apollonov, V. V.

    2016-08-01

    Dedicated to the 100th anniversary of the birth of Academician A M Prokhorov, this paper reviews the physics of self-sustained volume discharge without preionization—self-initiated volume discharge (SIVD)—in the working mixtures of non-chain hydrofluoride HF (deuterofluoride (DF)) lasers. The dynamics of SIVD in discharge gaps with different geometries is thoroughly described. The mechanisms for the restriction of current density in a diffuse channel in electric discharges in SF6 and SF6 based mixtures (which determines whether SIVD is possible) are proposed and analyzed using simple models. The most probable mechanisms are the electron impact dissociation of SF6 and other mixture components, electron-ion recombination and electron attachment to vibrationally excited SF6 molecules. Starting from a comparative analysis of the rate coefficients of these processes, it is shown that electron-ion recombination is capable of compensating for electron detachment from negative ions via electron impact. It is also established that SIVD is not only observed in SF6, but also in other strongly electronegative gases. The factors that determine the uniformity of the active medium in non-chain HF (DF) lasers are analyzed. Some special features of non-chain HF (DF) lasers with different apertures operating are carefully examined. Consideration is given to the problem of increasing the aperture and discharge volume of non-chain HF (DF) lasers. Based on our experimental results, the possibility of increasing the energy of such lasers to ~1 kJ and above is shown.

  4. On the VHF Source Retrieval Errors Associated with Lightning Mapping Arrays (LMAs)

    Science.gov (United States)

    Koshak, W.

    2016-01-01

    This presentation examines in detail the standard retrieval method: that of retrieving the (x, y, z, t) parameters of a lightning VHF point source from multiple ground-based Lightning Mapping Array (LMA) time-of-arrival (TOA) observations. The solution is found by minimizing a chi-squared function via the Levenberg-Marquardt algorithm. The associated forward problem is examined to illustrate the importance of signal-to-noise ratio (SNR). Monte Carlo simulated retrievals are used to assess the benefits of changing various LMA network properties. A generalized retrieval method is also introduced that, in addition to TOA data, uses LMA electric field amplitude measurements to retrieve a transient VHF dipole moment source.

  5. Broadband VHF observations for lightning impulses from a small satellite SOHLA-1 (Maido 1)

    Science.gov (United States)

    Morimoto, T.; Kikuchi, H.; Ushio, T.; Kawasaki, Z.; Hidekazu, H.; Aoki, T.

    2009-12-01

    Lightning Research Group of Osaka University (LRG-OU) has been developing VHF Broadband Digital Interferometer (DITF) to image precise lightning channels and monitor lightning activity widely. The feature of broadband DITF is its ultrawide bandwidth (from 25MHz to 100MHz) and implicit redundancy for estimating VHF source location. LRG-OU considers an application of the broadband DITF to the spaceborne measurement system and joins the SOHLA (Space Oriented Higashi-Osaka Leading Associate) satellite project. The SOHLA satellite project represents a technology transfer program to expand the range of the space development community in Japan. The objective is to get SMEs (Small and Medium sized manufacturing Enterprises) involved in small space projects and new space technologies. Under the cooperative agreement, JAXA (Japan Aerospace Exploration Agency) intends to contribute to socio-economic development by returning its R&D results to society, and SOHLA tries to revitalize the local economy through the commercialization of versatile small satellites. According to the agreement, JAXA provides SOHLA its technical information on small satellites and other technical assistance for the development of the small satellites, SOHLA-1. The prime objective of the SOHLA-1 program is to realize low-cost and short term development of a microsatellite which utilizes the components and bus technologies of JAXA’s MicroLabSat. SOHLA-1 is a spin-stabilized microsatellite of MicroLabSat heritage (about 50 kg). The spin axis is fixed to inertial reference frame. The spin axis (z-axis) lies in the plane containing the solar direction and the normal to the orbital plane. LRG-OU takes responsibility for a science mission of SOHLA-1. To examine the feasibility of the DITF receiving VHF lightning impulses in space, LRG-OU proposes the BMW (Broadband Measurement of Waveform for VHF Lightning Impulses). BMW consists of a single pair of an antenna, a band-pass filter, an amplifier, and an

  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. Electron heat flow in the auroral ionosphere inferred from EISCAT-VHF observations

    Energy Technology Data Exchange (ETDEWEB)

    Blelly, P.L.; Alcayde, D. [Universite Paul Sabatier, Toulouse (France)

    1994-07-01

    This paper discusses heat flows into electrons in auroral regions. Two different altitude regions are considered, one coincident with the F2 region, and one coincident with the upper ionosphere. Energy input comes from solar extreme ultraviolet radiation, and coupling of magnetospheric energy sources. The authors present a method to take advantage of EISCAT VHF radar observations to study these processes. They observe daily and seasonal variations in the heat inputs.

  10. Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

    Directory of Open Access Journals (Sweden)

    R. Sekar

    2004-09-01

    Full Text Available The VHF radars have been extensively used to investigate the structures and dynamics of equatorial Spread F (ESF irregularities. However, unambiguous identification of the nature of the structures in terms of plasma depletion or enhancement requires another technique, as the return echo measured by VHF radar is proportional to the square of the electron density fluctuations. In order to address this issue, co-ordinated radar backscatter and thermospheric airglow intensity measurements were carried out during March 2003 from the MST radar site at Gadanki. Temporal variations of 630.0-nm and 777.4-nm emission intensities reveal small-scale ("micro" and large-scale ("macro" variations during the period of observation. The micro variations are absent on non-ESF nights while the macro variations are present on both ESF and non-ESF nights. In addition to the well-known anti-correlation between the base height of the F-region and the nocturnal variation of thermospheric airglow intensities, the variation of the base height of the F-layer, on occasion, is found to manifest as a bottomside wave-like structure, as seen by VHF radar on an ESF night. The micro variations in the airglow intensities are associated with large-scale irregular plasma structures and found to be in correspondence with the "plume" structures obtained by VHF radar. In addition to the commonly observed depletions with upward movement, the observation unequivocally reveals the presence of plasma enhancements which move downwards. The observation of enhancement in 777.4-nm airglow intensity, which is characterized as plasma enhancement, provides an experimental verification of the earlier prediction based on numerical modeling studies.

  11. A beaded collar for dual micro GPS/VHF transmitter attachment to nutria

    Science.gov (United States)

    Haramis, G.M.; White, T.S.

    2011-01-01

    We report on the development of an approximately 85-g beaded collar for dual micro GPS/VHF transmitter attachment to semi-aquatic nutria (Myocastor coypus). Prototype collars were tested on captive nutria and refined during field trials. Central to the design was novel use of the VHF transmitter antenna as a collar. A circular collar was formed by passing the 44-cm antenna cable through a pre-made hole in the transmitter, leaving an approximately 16-cm upright antenna. GPS units were mounted separately via a hole in the base of each unit. For good satellite contact, GPS units (28 g) were maintained at the nape of the neck by counterbalance of the heavier VHF transmitters (50 g) positioned under the neck. To reduce friction, we lined the collar with alternate-sized plastic and, later, more durable nylon beads. The final collar configuration was worn for approximately 1 month deployments with only minor neck abrasion; one collar was worn successfully for 5 months. Foot entanglement remained the greatest risk of injury from the collar. By fitting collars tightly, we reduced the incidence of foot entanglement to 2 of 33 deployments (6%). Successful GPS tracks were acquired on 29 of 33 deployments (88%).

  12. 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

  13. 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.

  14. 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....

  15. 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.

  16. 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.

  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. 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.

  19. A thirty second isomer in Hf-171

    NARCIS (Netherlands)

    Campbell, P; Billowes, J; Cochrane, ECA; Cooke, JL; Cooper, TG; Dendooven, P; Evans, DE; Grant, IS; Griffith, JAR; Honkanen, A; Huhta, M; Oinonen, M; Pearson, MR; Penttila, H; Persson, B.L.; Richardson, DS; Tungate, G; Wheeler, PD; Zybert, L; Aysto, J

    1997-01-01

    An isomer has been detected in Hf-171 with a half-life of T-1/2 = 29.5(9) s. The state was populated in the Yb-170(alpha,3n)Hf-171m reaction at a beam energy of E-alpha = 50 MeV in an on-line ion guide isotope separator. The isomeric Hf-17lm(+) beam was extracted from the ion guide, mass-analysed an

  20. Novel uninterruptible self-determinate hybrid high-speed multimedia fiber optic wireless secure digital network

    Science.gov (United States)

    Lindsey, Lonnie

    2000-08-01

    One key to successful digital battlespace management is communications management. HF, UHF, VHF, CDMA, and SATCOM assets are difficult and complex to manage, and the modern digital battlespace adds new dimensions by including high volume multimedia transmissions, high-speed broadband data, and hyper-spectral sensor data. This environment requires more than the traditional voice transport-based communications system. The future sanctuary-based communication hub model will benefit from a novel uninterruptible self-determinate high bandwidth fiber optic system.

  1. The study of multilayers Fe/Hf and Ni/Hf by slow positron beam technique

    Science.gov (United States)

    Tashiro, Mutsumi; Nakajyo, Terunobu; Murashige, Yusuke; Koizumi, Tomoya; Kanazawa, Ikuzo; Komori, Fumio; Soe, We-Hyo; Yamamoto, Ryoichi; Ito, Yasuo

    1997-05-01

    The S-parameters versus the incident positron energy are measured in the Ni/Hf multilayer, thin Hf film, thin Fe film and the bilayer Fe/Hf. We have analyzed the change in vacancy-type defects in these multilayers and thin films with the deposition temperature in the MBE system.

  2. VHF-PECVD法制备氢化硅薄膜及单结电池%Hydrogented Microcrystalline Silicon Films and Single Junction Solar Cell by VHF-PECVD

    Institute of Scientific and Technical Information of China (English)

    吴志猛; 雷青松; 赵颖; 耿新华; 奚建平

    2005-01-01

    利用VHF-PECVD分解硅烷和氢气的混合气体来制备本征微晶硅薄膜.运用拉曼散射和X射线衍射研究了不同硅烷浓度对薄膜的影响.随着硅烷浓度的增加,沉积速率和光敏性增加而晶化率下降.将优化的本征材料应用到pin电池中,得到本征层厚度约为1μm的微晶电池,效率达5.87%.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. A study of finite volume effect on the multiple-frequencies coherence of VHF radar

    Science.gov (United States)

    Chen, Tsai-Yuan; Chu, Yen-Hsyang

    1993-08-01

    In the past few years, the technique of frequency domain interferometry (FDI) has been developed on VHF radar. By using this technique, the characteristics of a very thin atmospheric lay structure, which is embedded in the radar volume and cannot be solved by conventional VHF radar with only one operational frequency, can be determined through the calculation of the coherence and the phase from the two echo signals with different operational frequencies. According to FDI theory, assuming that the range and antenna beam weighting effect can be ignored, the coherence will approach zero if the layer thickness is fairly greater than the radar volume. However, in this study, it will be shown that if a rectangular pulse is transmitted and the atmospheric refractivity irregularities are distributed uniformly in the radar volume, that is, there is no narrow layer structure existing in the scattering volume, the coherence of two signals with different operational frequencies is still high and its behavior can be described by the equation C is approximately equal to Sinc((Delta)k L)/(l + N/S), where C is the coherence, Delta K is the wavenumber difference between two carrier frequencies, L is the effective scale of scattering volume, and N/S is the noise-to-signal power ratio. This feature can be interpreted physically by the finite volume filtering effect on the turbulent wavenumber spectrum. This theoretical prediction has been compared with the FDI experiments carried out by the Chung-Li VHF radar, and the results are quite reasonable. Thus, it is suggested that when the FDI technique is applied to estimate the thickness and the position of a thin layer, the finite volume filtering effect should be taken into account.

  15. HF radiation emitted by chaotic leader processes

    Science.gov (United States)

    Mäkelä, J. S.; Edirisinghe, M.; Fernando, M.; Montaño, R.; Cooray, V.

    2007-04-01

    This paper presents direct measurements of narrowband 10 MHz HF radiation from so-called “chaotic leaders” associated with subsequent return strokes. Although the term is controversial and poorly defined, we find that more than 30% of subsequent strokes in close lightning flashes contain electric field characteristics that are best described as “chaotic”. In earlier studies, return strokes have consistently been observed to be the strongest sources of HF radiation, but the results for leader processes are less consistent. We also observe return strokes to be the main HF emitter, and the leaders before the first return stroke in a flash sequence also emit HF though somewhat less intensely. The leaders preceding subsequent strokes typically emit little or no HF radiation, whether they are dart or dart-stepped leaders. However, it was observed that the presence of a chaotic component increases the leader HF intensity dramatically Defining the HF intensity unequivocally can be problematic for processes like chaotic leaders which have a combination of continuous and impulsive phenomena. Two time-domain methods were used to measure the HF intensity, the peak energy and the RMS energy. In the frequency domain these correspond to the energy spectral density (ESD) and power spectral density (PSD), respectively. It was found that the methods are not necessarily compatible. Thus, it is suggested that to clarify future work, leader processes should be characterized by the PSD rather than the ESD.

  16. 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.

  17. 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

  18. NEW DYNAMIC SLOT ASSIGNMENT SCHEME OF SELF-ORGANIZED TDMA VHF DATA LINK

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    According to the analysis of the very high frequency (VHF) self-organized time division multiple access (S-TDMA) aviation data link, a new dynamic slot assignment scheme is proposed in this paper, which adopts variable data frame structure and can eliminate the effect of the idle slot on message delay. By using queue theory, the analysis models of the new scheme and previous scheme are presented, and the performance of message delay and that of system throughput are analyzed under two schemes. The simulation results show that the new scheme has a better performance than the previous one in the message delay and system throughput.

  19. Measurements methodology for evaluation of Digital TV operation in VHF high-band

    Science.gov (United States)

    Pudwell Chaves de Almeida, M.; Vladimir Gonzalez Castellanos, P.; Alfredo Cal Braz, J.; Pereira David, R.; Saboia Lima de Souza, R.; Pereira da Soledade, A.; Rodrigues Nascimento Junior, J.; Ferreira Lima, F.

    2016-07-01

    This paper describes the experimental setup of field measurements carried out for evaluating the operation of the ISDB-TB (Integrated Services Digital Broadcasting, Terrestrial, Brazilian version) standard digital TV in the VHF-highband. Measurements were performed in urban and suburban areas in a medium-sized Brazilian city. Besides the direct measurements of received power and environmental noise, a measurement procedure involving the injection of Gaussian additive noise was employed to achieve the signal to noise ratio threshold at each measurement site. The analysis includes results of static reception measurements for evaluating the received field strength and the signal to noise ratio thresholds for correct signal decoding.

  20. HfS, Hyperfine Structure Fitting Tool

    CERN Document Server

    Estalella, Robert

    2016-01-01

    HfS is a tool to fit the hyperfine structure of spectral lines, with multiple velocity components. The HfS_nh3 procedures included in HfS fit simultaneously the hyperfine structure of the NH$_3$ (J,K)= (1,1) and (2,2) transitions, and perform a standard analysis to derive $T_\\mathrm{ex}$, NH$_3$ column density, $T_\\mathrm{rot}$, and $T_\\mathrm{k}$. HfS uses a Monte Carlo approach for fitting the line parameters. Especial attention is paid to the derivation of the parameter uncertainties. HfS includes procedures that make use of parallel computing for fitting spectra from a data cube.

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

    Directory of Open Access Journals (Sweden)

    L. J. Baddeley

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

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

  2. 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

  3. Aspects of HF radio propagation

    Directory of Open Access Journals (Sweden)

    Stephane Saillant

    2009-06-01

    Full Text Available

    radio systems. From the point of view Working Group 2 of the COST 296 Action, interest lies with effects associated

    with propagation via the ionosphere of signals within the HF band. Several aspects are covered in this paper:

    a The directions of arrival and times of flight of signals received over a path oriented along the trough have

    been examined and several types of propagation effects identified. Of particular note, combining the HF observations

    with satellite measurements has identified the presence of irregularities within the floor of the trough that

    result in propagation displaced from the great circle direction. An understanding of the propagation effects that

    result in deviations of the signal path from the great circle direction are of particular relevance to the operation

    of HF radiolocation systems.

    b Inclusion of the results from the above mentioned measurements into a propagation model of the northerly

    ionosphere (i.e. those regions of the ionosphere located poleward of, and including, the mid-latitude trough

    and the use of this model to predict the coverage expected from transmitters where the signals impinge on the

    northerly ionosphere

  4. A statistical study of underestimates of wind speeds by VHF radar

    Directory of Open Access Journals (Sweden)

    L. Thomas

    Full Text Available Comparisons are made between horizontal wind measurements carried out using a VHF-radar system at Aberystwyth (52.4°N, 4.1°W and radiosondes launched from Aberporth, some 50 km to the south-west. The radar wind results are derived from Doppler wind measurements at zenith angles of 6° in two orthogonal planes and in the vertical direction. Measurements on a total of 398 days over a 2-year period are considered, but the major part of the study involves a statistical analysis of data collected during 75 radiosonde flights selected to minimise the spatial separation of the two sets of measurements. Whereas good agreement is found between the two sets of wind direction, radar-derived wind speeds show underestimates of 4–6% compared with radiosonde values over the height range 4–14 km. Studies of the characteristics of this discrepancy in wind speeds have concentrated on its directional dependence, the effects of the spatial separation of the two sets of measurements, and the influence of any uncertainty in the radar measurements of vertical velocities. The aspect sensitivity of radar echoes has previously been suggested as a cause of underestimates of wind speeds by VHF radar. The present statistical treatment and case-studies show that an appropriate correction can be applied using estimates of the effective radar beam angle derived from a comparison of echo powers at zenith angles of 4.2° and 8.5°.

  5. Orographic role in anomalous VHF propagation on the background of impending earthquakes (EQ

    Directory of Open Access Journals (Sweden)

    Minakshi Devi

    2015-07-01

    Full Text Available The role of orographic factors in modifying atmospheric dynamics on the background of an impending earthquake (EQ that might lead to propagation of a signal beyond the Line Of Sight (LOS is examined in the paper. The analysis is based on the data of anomalous reception of VHF FM-signal at Gauhati University (GU, 26.15°N, 91.66°E, a station located in the sub Himalayan terrain. The signal reception records show that their anomalous appearance are associated closely with earthquake events of M >5.0, a phenomenon identified as EQ precursor. To identify sources of such reception, the paper presents some analytical approaches involving the terrain factors, impending EQ and atmospheric variabilities. Finally, the contribution of location/topography of the transmitter, receiver and epicenter in modifying the EQ induced atmospheric factors, is brought in to the ambit of analysis for explaining the observed over horizon VHF signal propagation. A special reference is made on the EQ time drop in temperature, increase in humidity and hence modification in Radio Refractive Index (RRI gradient, in favoring such reception. A model in support of the observation on EQ time lithosphere-atmosphere coupling relevant to widening of radio horizon limit is also proposed.

  6. Evaluation of multifrequency range imaging technique implemented on the Chung-Li VHF atmospheric radar

    Science.gov (United States)

    Chen, Jenn-Shyong; Tsai, Shih-Chiao; Su, Ching-Lun; Chu, Yen-Hsyang

    2016-05-01

    The multifrequency range imaging technique (RIM) has been implemented on the Chung-Li VHF array radar since 2008 after its renovation. This study made a more complete examination and evaluation of the RIM technique to facilitate the performance of the radar for atmospheric studies. RIM experiments with various radar parameters such as pulse length, pulse shape, receiver bandwidth, transmitter frequency set, and so on were conducted. The radar data employed for the study were collected from 2008 to 2013. It has been shown that two factors, the range/time delay of the signal traveling in the media and the standard deviation of Gaussian-shaped range-weighting function, play crucial roles in ameliorating the RIM-produced brightness (or power distribution); the two factors are associated with some radar parameters and system characteristics. The range/time delay of the signal was found to increase with time; moreover, it was slightly different for the echoes from the atmosphere with and without the presence of significant precipitation. A procedure of point-by-point correction of range/time delay was thus executed for the presence of precipitation to minimize the bogus brightness discontinuity at range gate boundaries. With the RIM technique, the Chung-Li VHF radar demonstrates its first successful observation of double-layer structures as well as their temporal and spatial variations with time.

  7. Varactor-tuned superconducting filter with constant absolute bandwidth at VHF-band

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bo [Department of Physics, Tsinghua University, Beijing 100084 (China); Cao, Bisong, E-mail: bscao@tsinghua.edu.cn [Department of Physics, Tsinghua University, Beijing 100084 (China); Guo, Xubo; Zhang, Xiaoping [Department of Physics, Tsinghua University, Beijing 100084 (China); Chen, Yidong [Superconductor Technology Co., Ltd, Beijing 100085 (China); Wei, Bin; Jiang, Linan [Department of Physics, Tsinghua University, Beijing 100084 (China)

    2015-09-15

    Highlights: • A four-pole superconducting tunable filter at VHF-band with constant absolute bandwidth is proposed. • The novel resonator consists of a spiral-in-spiral-out (SISO) microstrip line with one end shorted to ground and the other loaded with a varactor diode. • Both combline and interdigital constructions for coupling are introduced, and tuned to meet the constant bandwidth requirements. • The measurements show bandwidth variation is less than 1.3% while tuning from 247.28 to 266.58 MHz, and a high Q{sub u} of 1600–5500 is archived. - Abstract: A four-pole superconducting tunable filter at VHF-band with constant absolute bandwidth is proposed. The resonator consists of a spiral-in-spiral-out (SISO) resonator with one end shorted to ground and the other end loaded with a varactor diode. Both combline and interdigital constructions for coupling are introduced, and tuned to meet the constant bandwidth requirement. The fabricated device has a compact size, a tuning range of 7.3% from 247.28 to 266.58, a 3-dB bandwidth of 2.32 ± 0.03 MHz. The insertion loss ranges from 0.5 to 1.6 dB, yielding a high unloaded Q of 1600–5500. The simulated and measured results show an excellent agreement.

  8. Digital audio broadcasting: Measuring techniques and coverage performance for a medium power VHF single frequency network

    Science.gov (United States)

    Maddocks, M. C. D.; Eng, C.; Pullen, I. R.; Green, J. A.

    1995-02-01

    The advent of digital formats such as CD has created demand for uniformly high audio quality from radio. In order to provide such high-quality stereo reception, a Digital Audio Broadcasting (DAB) system capable of reliable reception in vehicles and on portables has been developed by the European EUREKA 147 Project. As a VHF frequency allocation would appear most suitable for the introduction of terrestrial broadcasting of DAB in the United Kingdom, the BBC is undertaking a major experiment to test the EUREKA DAB system and to generate data to allow efficient planning of its transmitter network. A network of four, 1 kW e.r.p., VHF transmitters has been installed to cover the London area in England. This Report describes the experimental program and the rationale and measurement techniques behind it. The results show a wide-area coverage from the transmitter network which is in reasonable agreement with computer predictions. This indicates that the current transmitting and receiving equipment (built to the EUREKA specification) is operating in the way that would be expected from theoretical studies and simulation. The results also provide quantitative values which can be used for coverage prediction and for international co-ordination of services. Finally, the performance of the system demonstrates a number of the benefits of the EUREKA DAB system for mobile and portable reception.

  9. PMSE strength during enhanced D region electron densities: Faraday rotation and absorption effects at VHF frequencies

    Science.gov (United States)

    Chau, Jorge L.; Röttger, Jürgen; Rapp, Markus

    2014-10-01

    In this paper we study the effects of absorption and Faraday rotation on measurements of polar mesosphere summer echoes (PMSE). We found that such effects can produce significant reduction of signal-to-noise ratio (SNR) when the D region electron densities (Ne) are enhanced, and VHF radar systems with linearly polarized antennas are used. In particular we study the expected effects during the strong solar proton event (SPE) of July 2000, also known as the Bastille day flare event. During this event, a strong anti-correlation between the PMSE SNR and the D-region Ne was found over three VHF radar sites at high latitudes: Andøya, Kiruna, and Svalbard. This anti-correlation has been explained (a) in terms of transport effects due to strong electric fields associated to the SPE and (b) due to a limited amount of aerosol particles as compared to the amount of D-region electrons. Our calculations using the Ne profiles used by previous researchers explain most, if not all, of the observed SNR reduction in both time (around the SPE peak) and altitude. This systematic effect, particularly the Faraday rotation, should be recognized and tested, and possibly avoided (e.g., using circular polarization), in future observations during the incoming solar maximum period, to contribute to the understanding of PMSE during enhanced D region Ne.

  10. 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

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

    Science.gov (United States)

    Petrariu, Adrian-Ioan; Popa, Valentin

    2016-01-01

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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Omohimire P. Omolaye

    2015-09-01

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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. Thin film silicon n–i–p solar cells deposited by VHF PECVD at 100 °C substrate temperature

    NARCIS (Netherlands)

    Brinza, M.; Rath, J.K.; Schropp, R.E.I.

    2009-01-01

    The applicability of the very high frequency (VHF) plasma-enhanced chemical vapor deposition (PECVD) technique to the fabrication of solar cells in an n–i–p configuration at 100 °C substrate temperature is being investigated. Amorphous and microcrystalline silicon cells are made with the absorber la

  9. 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.

  10. High-latitude HF Doppler observations of ULF waves: 2. Waves with small spatial scale sizes

    Directory of Open Access Journals (Sweden)

    D. M. Wright

    Full Text Available The DOPE (Doppler Pulsation Experiment HF Doppler sounder located near Tromsø, Norway (geographic: 69.6°N 19.2°E; L = 6.3 is deployed to observe signatures, in the high-latitude ionosphere, of magnetospheric ULF waves. A type of wave has been identified which exhibits no simultaneous ground magnetic signature. They can be subdivided into two classes which occur in the dawn and dusk local time sectors respectively. They generally have frequencies greater than the resonance fundamentals of local field lines. It is suggested that these may be the signatures of high-m ULF waves where the ground magnetic signature has been strongly attenuated as a result of the scale size of the waves. The dawn population demonstrate similarities to a type of magnetospheric wave known as giant (Pg pulsations which tend to be resonant at higher harmonics on magnetic field lines. In contrast, the waves occurring in the dusk sector are believed to be related to the storm-time Pc5s previously reported in VHF radar data. Dst measurements support these observations by indicating that the dawn and dusk classes of waves occur respectively during geomagnetically quiet and more active intervals.

    Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions · Magnetospheric physics (MHD waves and instabilities

  11. HF Transverse Segmentation and Tagging Jet Capability

    CERN Document Server

    Doroshkevich, E A; Kuleshov, Sergey

    1998-01-01

    So called tagging jets and pile-up were simulated for the optimisation of the HF segmentation. The energy resolution, angular resolution and efficiency of jet reconstruction are defined for different calorimeter segmentation.

  12. Collisional quenching of highly rotationally excited HF

    CERN Document Server

    Yang, Benhui; Forrey, R C; Stancil, P C; Balakrishnan, N

    2015-01-01

    Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations of the interstellar gas for nonlocal thermodynamic equilibrium line formation. Theoretical cross sections and rate coefficients for collisional deexcitation of rotationally excited HF in the vibrational ground state are reported. The quantum-mechanical close-coupling approach implemented in the nonreactive scattering code MOLSCAT was applied in the cross section and rate coefficient calculations on an accurate 2D HF-He potential energy surface. Estimates of rate coefficients for H and H$_2$ colliders were obtained from the HF-He collisional data with a reduced-potential scaling approach. The calculation of state-to-state rotational quenching cross sections for HF due to He with initial rotational levels up to $j=20$ were performed for kinetic energies from 10$^{-5}$ to 15000...

  13. Microhardness evaluation alloys Hf-Si-B; Avaliacao de microdureza de ligas Hf-Si-B

    Energy Technology Data Exchange (ETDEWEB)

    Gigolotti, Joao Carlos Janio; Costa, Eliane Fernandes Brasil [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Rocha, Elisa Gombio; Coelho, Gilberto Carvalho, E-mail: carlosjanio@uol.com.br, E-mail: eliane-costabrasi@hotmail.com, E-mail: cnunes@demar.eel.usp.br, E-mail: elisarocha@alunos.eel.usp.br, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-08-15

    The technological advance has generated increasing demand for materials that can be used under high temperature, what includes intermetallic MR-Si-B (MR = refractory metal) alloys with multiphase structures, that can also be applied in oxide environments. Thus, this work had for objective the micro hardness study of the Hf-Si-B system alloys, heat treated at 1600 deg C, in the Hf rich region. Hf-Si-B alloys had been produced with blades of Hf (min. 99.8%), Si (min. 99.998%) and B (min. 99.5%), in the voltaic arc furnace and heat treated at 1600 deg C under argon atmosphere. The relationship of the phases had been previously identified by X-ray diffraction and contrast in backscattered electron imaging mode. The alloys had their hardness analyzed by method Vickers (micro hardness) with load of 0.05 kgf and 0.2 kgf and application time of 20 s. The results, obtained from the arithmetic mean of measurements for each alloy on the heterogeneous region, showed a mean hardness of 11.08 GPA, with small coefficient of variation of 3.8%. The borides HfB2 (19.34 GPa) e HfB - 11.76 GPa, showed the hardness higher than the silicides Hf2Si (8.57 GPa), Hf5Si3 (9.63 GPa), Hf3Si2 (11.66 GPa), Hf5Si4 (10.00 GPa), HfSi (10.02 GPa) e HfSi2 (8.61 GPa). (author)

  14. 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.

  15. 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.

  16. Complementary code and digital filtering for detection of weak VHF radar signals from the mesoscale. [SOUSY-VHF radar, Harz Mountains, Germany

    Science.gov (United States)

    Schmidt, G.; Ruster, R.; Czechowsky, P.

    1983-01-01

    The SOUSY-VHF-Radar operates at a frequency of 53.5 MHz in a valley in the Harz mountains, Germany, 90 km from Hanover. The radar controller, which is programmed by a 16-bit computer holds 1024 program steps in core and controls, via 8 channels, the whole radar system: in particular the master oscillator, the transmitter, the transmit-receive-switch, the receiver, the analog to digital converter, and the hardware adder. The high-sensitivity receiver has a dynamic range of 70 dB and a video bandwidth of 1 MHz. Phase coding schemes are applied, in particular for investigations at mesospheric heights, in order to carry out measurements with the maximum duty cycle and the maximum height resolution. The computer takes the data from the adder to store it in magnetic tape or disc. The radar controller is programmed by the computer using simple FORTRAN IV statements. After the program has been loaded and the computer has started the radar controller, it runs automatically, stopping at the program end. In case of errors or failures occurring during the radar operation, the radar controller is shut off caused either by a safety circuit or by a power failure circuit or by a parity check system.

  17. 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.

  18. A numerical method for imaging of biological microstructures by VHF waves

    CERN Document Server

    Ala, Guido; Francomano, Elisa; Ganci, Salvatore

    2013-01-01

    Imaging techniques give a fundamental support to medical diagnostics during the pathology discovery as well as for the characterization of biological structures. The imaging methods involve electromagnetic waves in a frequency range that spans from some Hz to GHz and over. Most of these methods involve scanning of wide human body areas even if only small areas need to be analyzed. In this paper, a numerical method to evaluate the shape of micro-structures for application in the medical ?field, with a very low invasiveness for the human body, is proposed. A flexible thin-wire antenna radiates the VHF waves and then, by measuring the spatial magnetic ?field distribution it is possible to reconstruct the micro-structures image by estimating the location of the antenna against a sensors panel. The typical inverse problem described above is solved numerically, and ?first simulation results are presented in order to show the validity and the robustness of the proposed approach.

  19. Graphene-based tunable non-foster circuit for VHF applications

    Science.gov (United States)

    Tian, Jing; Nagarkoti, Deepak Singh; Rajab, Khalid Z.; Hao, Yang

    2016-06-01

    This paper presents a negative impedance converter (NIC) based on graphene field effect transistors (GFETs) for VHF applications. The NIC is designed following Linvill's open circuit stable (OCS) topology. The DC modelling parameters of GFET are extracted from a device measured by Meric et al. [IEEE Electron Devices Meeting, 23.2.1 (2010)] Estimated parasitics are also taken into account. Simulation results from Keysight Advanced Design System (ADS) show good NIC performance up to 200 MHz and the value of negative capacitance is directly proportional to the capacitive load. In addition, it has been shown that by varying the supply voltage the value of negative capacitance can also be tuned. The NIC stability has been tested up to 2 GHz (10 times the maximum operation frequency) using Nyquist stability criterion to ensure there are no oscillation issues.

  20. Graphene-based tunable non-foster circuit for VHF applications

    Directory of Open Access Journals (Sweden)

    Jing Tian

    2016-06-01

    Full Text Available This paper presents a negative impedance converter (NIC based on graphene field effect transistors (GFETs for VHF applications. The NIC is designed following Linvill’s open circuit stable (OCS topology. The DC modelling parameters of GFET are extracted from a device measured by Meric et al. [IEEE Electron Devices Meeting, 23.2.1 (2010] Estimated parasitics are also taken into account. Simulation results from Keysight Advanced Design System (ADS show good NIC performance up to 200 MHz and the value of negative capacitance is directly proportional to the capacitive load. In addition, it has been shown that by varying the supply voltage the value of negative capacitance can also be tuned. The NIC stability has been tested up to 2 GHz (10 times the maximum operation frequency using Nyquist stability criterion to ensure there are no oscillation issues.

  1. Effect of diffraction on the ultrasonic velocity measured by the pulse interference method in VHF range

    Institute of Scientific and Technical Information of China (English)

    WEI Tingcun

    2002-01-01

    The effect of diffraction on the ultrasonic velocity measured by the pulse interference method has been investigated in VHF range theoretically and experimentally. Two silicate glasses are taken as the specimens, their frequency dependences of longitudinal velocities are measured in the frequency range of 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect are calculated using A. O. Williams' theoretical expression. For the velocity error due to diffraction effect, the experimental results are in good agreement with the theoretical prediction. It has been shown that the velocity error due to diffraction effect is directly proportional to d θ21 (f)/df, where θ21 (f) is the phase advances difference between the two partial reflection signals used in velocity measurement and f is the ultrasonic frequency.

  2. Influence of total gas flow rate on microcrystalline silicon films prepared by VHF-PECVD

    Institute of Scientific and Technical Information of China (English)

    Gao Yan-Tao; Zhang Xiao-Dan; Zhao Ying; Sun Jian; Zhu Feng; Wei Chang-Chun; Chen Fei

    2006-01-01

    Hydrogenated microcrystalline silicon (μc-Si:H) films are fabricated by very high frequency plasma enhanced chemical vapour deposition (VHF-PECVD) at a silane concentration of 7% and a varying total gas flow rate (H2+SiH4).Relations between the total gas flow rate and the electrical and structural properties as well as deposition rate of the films are studied. The results indicate that with the total gas flow rate increasing the photosensitivity and deposition rate increase, but the crystalline volume fraction (Xc) and dark conductivity decrease. And the intensity of (220) peak first increases then decreases with the increase of the total gas flow rate. The cause for the changes in the structure and deposition rate of the films with the total gas flow rate is investigated using optical emission spectroscopy (OES).

  3. Field emission from carbon films deposited by VHF CVD on difference substrates

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, A A; Andronov, A N; Felter, T E; Ioffe, A F; Kosarev, A I; Shotov, M V; Vinogradov, A J

    1999-04-01

    As previously demonstrated, non-diamond carbon (NDC) films deposited at low temperatures 200-300 C on silicon tips reduced the threshold of field emission. In this paper we will present the results of the study of field emission from flat NDC films prepared by VHF CVD. Emission measurements were performed in a diode configuration at approximately 10{sup {minus}10} Torr. NDC films were deposited on ceramic and on c-Si substrates sputter coated with layers of Ti, Cu, Ni and Pt. The back contact material influences the emission characteristics but not as a direct correlation to work function. A model of field emission from metal-NDC film structures will be discussed.

  4. Final environmental assessment for vegetation control at VHF stations, microwave stations, electrical substations, and pole yards

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-13

    Southwestern Power Adm. operates very high frequency (VHF) and microwave radio stations, electrical substations, and pole yards for electric power transmission throughout AR, MO, and OK. Vegetation growth at the stations must be suppressed for safety of operation and personnel. Southwestern has been using a combination of mechanical/manual and herbicide control for this purpose; Federally- mandated reductions in staff and budgetary resources require Southwestern to evaluate all potentially efficient methods for vegetation control. Three alternatives were examined: no action, mechanical/manual control, and (proposed) a combination of mechanical/manual and herbicide control. Environmental impacts on air and water quality, wetlands, wildlife, endangered species, archaeological and other resources, farmland, human health, transportation, etc. were evaluated.

  5. 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".

  6. Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar

    Directory of Open Access Journals (Sweden)

    T. Maruyama

    2006-03-01

    Full Text Available During the SEEK 2 rocket campaign, ionograms were recorded every minute at the Yamagawa Radio Observatory at about 90km west of the region monitored by a VHF (very high frequency coherent backscatter radar. Sporadic E-layer parameters, which include the critical (foEs and blanketing (fbEs frequencies, the layer height (h'Es, and the width of the range spread of sporadic E-traces, were compared with RTI (range-time-intensity plots of VHF quasi-periodic (QP and continuous coherent backscatter echoes. A close relationship was found between the appearance of QP echoes in the RTI plots and the level of spatial inhomogeneity in sporadic E plasma, signified here by the difference between foEs and fbEs. During QP echo events, foEs increased while fbEs decreased, so that the difference foEs-fbEs was enhanced, indicating the development of strong spatial structuring in electron density within a sporadic E-layer. On the other hand, increases in sporadic E range spreading also correlated with the occurrence of QP echoes but the degree of correlation varied from event to event. Continuous radar echoes were observed in association with low altitude sporadic E-layers, located well below 100 km and at times as low as 90 km. During the continuous echo events, both foEs and fbEs were less variable, and the difference foEs-fbEs was small and not as dynamic as in the QP echoes. On the other hand, the Es-layer spread intensified during continuous echoes, which means that some patchiness or corrugation in those low altitude layers is also necessary for the continuous backscatter echoes to take place.

  7. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source

    Science.gov (United States)

    Wells, R. P.; Ghiorso, W.; Staples, J.; Huang, T. M.; Sannibale, F.; Kramasz, T. D.

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  8. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source.

    Science.gov (United States)

    Wells, R P; Ghiorso, W; Staples, J; Huang, T M; Sannibale, F; Kramasz, T D

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. General concepts of modern HF communications

    Science.gov (United States)

    Aarons, Jules

    Both conceptual and hardware advancements have led to substantial systems developments in military HF communications; the former encompass coding and error correction techniques for security, in order to minimize propagation and interference, while the latter prominently include digital equipment permitting the selection of a frequency for a particular path and propagation mode, as well as modulation selection. Propagation-related advancements involve better statistical models as well as advancements in short-term forecasting methods responsive to changes in solar-geophysical parameters. Adaptive HF systems have been developed for meteor-scatter radio communications.

  5. Research on Multi-Layer Distributed HF Radio Network Structure

    Institute of Scientific and Technical Information of China (English)

    Hui Dai; Chun-Jiang Wang; Quan Yu

    2008-01-01

    High frequency (HF) transmission is an important communication techniques. However, conventional point-to-point transmission can be easily destroyed, which limits its utilization in practice. HF networking communication has the capability against demolishment. The network structure is one of the key factors for HF networking communication. In this paper, a novel analysis method of the network connectedness based on the eigenvalue is derived, and a multi-layer distributed HF radio network structure is proposed. Both the theore tical analysis and the computer simulation results verify that the application of the proposed network structure in the HF radio communication can improve the anti demolishment ability of the HF network efficiently.

  6. VHF volume-imaging radar observation of aspect-sensitive scatterers tilted in mountain waves above a convective boundary layer

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    2005-06-01

    Full Text Available Thin stable atmospheric layers cause VHF radars to receive increased echo power from near zenith. Layers can be tilted from horizontal, for instance by gravity waves, and the direction of VHF "glinting" is measurable by spatial domain interferometry or many-beam Doppler beam swinging (DBS. This paper uses the Middle and Upper atmosphere (MU radar, Shigaraki, Japan as a volume-imaging radar with 64-beam DBS, to show tilting of layers and air flow in mountain waves. Tilt of aspect-sensitive echo power from horizontal is nearly parallel to air flow, as assumed in earlier measurements of mountain-wave alignment. Vertical-wind measurements are self-consistent from different beam zenith angles, despite the combined effects of aspect sensitivity and horizontal-wind gradients.

  7. 浅谈长江三峡河段VHF系统干扰控制策略%On the Yangtze River Three Gorges VHF System Interference Control Strategy

    Institute of Scientific and Technical Information of China (English)

    李雯; 侯国佼

    2015-01-01

    This paper discusses the Three Gorges river VHF interference factors, combined with the status quo of the Three Gorges river analyze the causes VHF system interference, system interference VHF propose appropriate control strategies.%文章讨论了三峡河段VHF干扰影响因素,结合三峡河段VHF系统干扰现状分析原因,提出相应的VHF系统干扰控制策略。

  8. First results from an iron lidar and a VHF radar at Davis, Antarctica

    Science.gov (United States)

    Luebken, F.; Morris, R. J.; Hoeffner, J.; Kaifler, B.; Viehl, T.

    2012-12-01

    We present temperature measurements at Davis, Antarctica (69°S, 78°E), and compare with simultaneous and co-located radar measurements of polar mesosphere summer echoes (PMSE). The mobile scanning iron lidar of the IAP in Kuehlungsborn was installed at Davis in December 2010. It measures iron densities, vertical winds, and temperatures in the iron layer, i. e. from approximately 80 to 100 km. It is based on probing the Doppler broadened resonance line of iron atoms at 386 nm and can operate under daylight conditions. Typical values for temperature uncertainty, altitude and time resolution are 3-5 K, 1 km, and 1 hour, respectively. The lidar also measures neutral air densities and temperatures in the stratosphere and lower mesosphere. At Davis the lidar has up to now achieved approximately 2700 hours of data which is presumably the largest nearly continuous data set in Antarctica. The mesopause altitude changes throughout the summer season by several kilometers, significantly different from the northern hemisphere summer. Depending on altitude, temperatures can be warmer or colder compared to the NH summer. Temperatures at Davis near 86 km are rather similar to the NH, but they are much colder at higher altitudes. The thermal structure around the mesopause at Davis is closely related to the general circulation in the stratosphere, namely to the transition from winter to summer conditions. Different from expectations we sometimes find the mesopause significantly higher and colder(!) compared to the NH. Furthermore, we find large thermal tides in the summer months with amplitudes of up to 6-7~K, which is much larger than expected from models. The Australien Antarctic Division operates a 55 MHz VHF radar at Davis since February 2003. We report first simultaneous measurements of PMSE and temperatures by the Fe lidar. PMSE are strong radar echoes related to ice particles and therefore require atmospheric temperatures being lower than the frost point temperature

  9. Systematic Comparison of HF CMOS Transconductors

    NARCIS (Netherlands)

    Klumperink, Eric A.M.; Nauta, Bram

    2003-01-01

    Transconductors are commonly used as active elements in high-frequency (HF) filters, amplifiers, mixers, and oscillators. This paper reviews transconductor design by focusing on the V-I kernel that determines the key transconductor properties. Based on bandwidth considerations, simple V-I kernels wi

  10. Electron impact on vibrationally cold {{HF}}^{+}

    Science.gov (United States)

    Cristian Stroe, Marius; Fifirig, Magda

    2016-12-01

    The dissociative recombination and vibrational excitation processes induced by electron impact on vibrationally cold {{HF}}+ are investigated in the framework of the multichannel quantum defect theory for electron energies below 1 eV. The thermal rate coefficients for the electron temperature range from 10 to 5000 K are reported.

  11. ORIGIN OF EXCESS (176)Hf IN METEORITES

    DEFF Research Database (Denmark)

    Thrane, Kristine; Connelly, James Norman; Bizzarro, Martin

    2010-01-01

    After considerable controversy regarding the (176)Lu decay constant (lambda(176)Lu), there is now widespread agreement that (1.867 +/- 0.008) x 10(-11) yr(-1) as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the (176)Hf excesses that are correlated with...

  12. 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.

  13. 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.

  14. 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

  15. Pressure dependent tailored attributes of silicon nanoneedles grown by VHF plasma technique

    Science.gov (United States)

    Mohammed, Yasir Hussein; Sakrani, Samsudi Bin; Rohani, Md Supar

    2016-06-01

    Gold (Au) catalysts assisted well-aligned silicon nanoneedles (SiNNs) are synthesized using very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The tailored morphology and the optical reflectance of such NNs are inspected as a function of varying reactor pressure (200-800 mTorr). FESEM images revealed the growth of high density SiNNs with diameter ranging from 45 to 600 nm and length as much as 5.66 ± 0.2 μm. Overall morphology of these NNs are found to be highly sensitive to the pressure variation, where appreciably aligned thinner NNs are achieved at 600 mTorr pressure. The presence of globule at the NNs tip authenticated their VLS mechanism mediated growth. The reactor pressure sensitivity of the aspect ratio, lattice parameters, Raman modes, and reflectance are demonstrated. XRD patterns manifested SiNNs cubic crystalline phase with preferred orientation along direction. The occurrence of NNs high crystallinity is further supported by the Raman and HRTEM data. The reflectance of SiNNs grown at 600 mTorr exhibited remarkable reduction (˜6.3%) than those obtained at other pressures. This reactor pressure dependent significant modification in the physical properties of synthesized SiNNs may be prospective for the development of optoelectronics.

  16. Long-period unstable gravity-waves and associated VHF radar echoes

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    Full Text Available VHF atmospheric radar is used to measure the wind velocity and radar echo power related to long-period wind perturbations, including gravity waves, which are observed commonly in the lower stratosphere and tropopause region, and sometimes in the troposphere. These wind structures have been identified previously as either inertia-gravity waves, often associated with jet streams, or mountain waves. At heights of peak wind shear, imbalances are found between the echo powers of a symmetric pair of radar beams, which are expected to be equal. The largest of these power differences are found for conditions of simultaneous high wind shear and high aspect sensitivity. It is suggested that the effect might arise from tilted specular reflectors or anisotropic turbulent scatterers, a result of, for example, Kelvin-Helmholtz instabilities generated by the strong wind shears. This radar power-difference effect could offer information about the onset of saturation in long-period waves, and the formation of thin layers of turbulence.

  17. A New 50-MHz VHF Digital Bistatic Radar for E-region Space Physics Research

    Science.gov (United States)

    Hussey, G. C.; Huyghebaert, D. R.; St-Maurice, J. P.; McWilliams, K. A.

    2015-12-01

    A new fully digital bistatic 50-MHz VHF radar is currently being developed by the radar group in the Institute of Space and Atmospheric Studies (ISAS) at the University of Saskatchewan. This paper presents the scientific motivation for the new radar. Traditionally bistatic radars have had excellent time resolution, but were significantly lacking in range resolution. With the now available accurate timing abilities and advanced pulse modulation techniques, bistatic radar configurations with both excellent temporal and spatial resolution are able to map or 'image' the E-region. The E-region portion of the ionosphere being the base of the magnetosphere has both global (ionosphere-magnetosphere system) and local phenomena of interest. The currents in the magnetosphere close in the E-region. Field-aligned currents (FACs) and Alfven waves are phenomena with origins in the magnetosphere which present their 'signatures' in the E-region. For example, Alfven waves (produced by the Alfven wave resonator) have different time scales, from less than a Hertz to periods of tens of minutes --- and the high temporal and spatial resolution of this new digital E-region radar will be able to detect them all. The E-region is also a dynamic plasma medium with the two-steam and gradient drift instabilities present and the improved measurement abilities will give fresh physical insight.

  18. Study of CNT growth using nanocatalyst Ag precursor by HWC-VHF-PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Eliyana, Ajeng; Rosikin, Ahmad; Winata, Toto, E-mail: toto@fi.itb.ac.id [Physics of Electronics Material Research Division, Physics Programme, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, West Java (Indonesia)

    2015-04-16

    The study of CNT growth has been done by using silver (Ag) nanocatalyst as a guide precursor on corning glass 7059 substrate. The silver catalyst was prepared by the evaporation method by varying deposition time for 50, 25, and 14 seconds. The silver films were then annealed at temperature of 400°C for 4 hours. From Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) results the grain sizes are 65 nm, 57 nm, and 33 nm, and also the atomic compositions are 6,06%, 4,52%, and 3,73% for 14, 25 and 50 seconds samples, respectively. The 33 nm samples were then used for CNT growth by using Hot Wire Cell (HWC) – Very High Frequency (VHF) – Plasma Enhanced Chemical Vapor Deposition (PECVD) at 275 ° C deposition temperature and pressure of 300 mTorr. The rf power was varied from 8 to 20 watts, with deposition time for 60 minutes. The methane (CH4) 99.999% was used as Carbon sources. Hydrogen gas (H2) was used to etch the oxide layer formed during the pre-deposition process. The diameter and length for the CNT are 125 nm and 1.650 to 2.989 nm respectively.

  19. P-μc-Si1-xGex:H thin film by VHF-PECVD

    Institute of Scientific and Technical Information of China (English)

    SHANG Ze-ren; ZHANG jian-jun; ZHANG Li-ping; HU Zeng-xin; XUE Jun-ming; ZHAO Ying; GENG Xin-hua

    2008-01-01

    In this paper,a series of boron doped microcrystalline hydrogenated silicon-germanium(p-μc-Si1-xGex:H)was deposited by very high frequency plasma-enhanced chemical vapor deposition(VHF-PECVD)from SiH4 and GeF4 mixtures.The effect of GeF4concentration on films'composition.structure and electrical properties was studied.The resuIts show tllat with the increase of GeF4 concentration,the Ge fraction x increases.The dark conductivity and crystalline volume fraction increase first,and then decrease.When the GC is 4%,p-μc-Si1-xGex:H matefiai with high conductivity,low activation energy(σ=1.68 S/cm,Eg=0.047 eV),high crystalline volume fraction (60%)and with an average transmission coefficient over the long wave region reaching 0.9 at the thickness of 72 am was achieved.The experimental results were discussed in detail.

  1. Spatial and temporal characteristics of VHF radiation source produced by lightning in supercell thunderstorms

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yijun; MENG Qing; P. R. Krehbiel; LIU Xinsheng; ZHOU Xiuji

    2004-01-01

    The three-dimensional temporal and spatial characteristics of VHF radiation events produced by lightning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning mapping array system with high time and space resolution. The results indicate that lightning hole (lighting free region) with about 5-6 km in diameter or lighting ring (annular lighting free region) is associated with the strong updraft in thunderstorm. The lasting time of lightning holes is either short or long, being about 20 min in a tornado-producing thunderstorm. The lightning holes appear before the occurrence of tornado. The lightning hole is the most obvious during the occurrence of tornado and some self-existent lighting radiation events appear at a height of 15-16 km. The lightning channels of inter-cloud (IC) lightning discharge exhibit clockwise rotary structures and do not have clear bilevel structures in the vicinity of the tornado. The lightning holes are corresponding to the strong updraft region. The temporal and spatial distribution of lightning radiation events reveals the structure of strong updraft in supercell thunderstorms.Positive cloud-to-ground (CG) lightning discharges dominate in these thunderstorms and the peak of positive CG lightning flash rate appears, with the maximum of 6 per minute, after or before the occurrence of tornado.

  2. Range imaging observations of PMSE using the EISCAT VHF radar: Phase calibration and first results

    Directory of Open Access Journals (Sweden)

    J. R. Fernandez

    2005-01-01

    Full Text Available A novel phase calibration technique for use with the multiple-frequency Range IMaging (RIM technique is introduced based on genetic algorithms. The method is used on data collected with the European Incoherent SCATter (EISCAT VHF radar during a 2002 experiment with the goal of characterizing the vertical structure of Polar Mesosphere Summer Echoes (PMSE over northern Norway. For typical Doppler measurements, the initial phases of the transmitter and receiver are not required to be the same. The EISCAT receiver systems exploit this fact, allowing a multi-static configuration. However, the RIM method relies on the small phase differences between closely spaced frequencies. As a result, the high-resolution images produced by the RIM method can be significantly degraded if not properly calibrated. Using an enhanced numerical radar simulator, in which data from multiple sampling volumes are simultaneously generated, the proposed calibration method is validated. Subsequently, the method is applied to preliminary data from the EISCAT radar, providing first results of RIM images of PMSE. Data using conventional analysis techniques, and confirmed by RIM, reveal an often-observed double-layer structure with higher stability in the lower layer. Moreover, vertical velocity oscillations exhibit a clear correlation with the apparent motion of the layers shown in the echo power plots.

  3. Frequency domain interferometry mode observations of PMSE using the EISCAT VHF radar

    Directory of Open Access Journals (Sweden)

    P. B. Chilson

    Full Text Available During the summer of 1997 investigations into the nature of polar mesosphere summer echoes (PMSE were conducted using the European incoherent scatter (EISCAT VHF radar in Norway. The radar was operated in a frequency domain interferometry (FDI mode over a period of two weeks to study the frequency coherence of the returned radar signals. The operating frequencies of the radar were 224.0 and 224.6 MHz. We present the first results from the experiment by discussing two 4-h intervals of data collected over two consecutive nights. During the first of the two days an enhancement of the FDI coherence, which indicates the presence of distinct scattering layers, was found to follow the lower boundary of the PMSE. Indeed, it is not unusual to observe that the coherence values are peaked around the heights corresponding to both the lower- and upper-most boundaries of the PMSE layer and sublayers. A Kelvin-Helmholtz mechanism is offered as one possible explanation for the layering structure. Additionally, our analysis using range-time-pseudocolor plots of signal-to-noise ratios, spectrograms of Doppler velocity, and estimates of the positions of individual scattering layers is shown to be consistent with the proposition that upwardly propagating gravity waves can become steepened near the mesopause.

    Key words: Ionosphere (polar ionosphere · Meteorology and Atmospheric Dynamics (middle atmosphere dynamics · Radio Science (Interferometry

  4. 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.

  5. 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.

  6. 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。

  7. 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.

  8. 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.

  9. 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.

  10. On auroral dynamics observed by HF radar: 1. Equatorward edge of the afternoon-evening diffuse luminosity belt

    Directory of Open Access Journals (Sweden)

    M. Uspensky

    Full Text Available Observations and modelling are presented which illustrate the ability of the Finland CUTLASS HF radar to monitor the afternoon-evening equatorward auroral boundary during weak geomagnetic activity. The subsequent substorm growth phase development was also observed in the late evening sector as a natural continuation of the preceding auroral oval dynamics. Over an 8 h period the CUTLASS Finland radar observed a narrow (in range and persistent region of auroral F- and (later E-layer echoes which gradually moved equatorward, consistent with the auroral oval diurnal rotation. This echo region corresponds to the subvisual equatorward edge of the diffuse luminosity belt (SEEL and the ionospheric footprint of the inner boundary of the electron plasma sheet. The capability of the Finland CUTLASS radar to monitor the E-layer SEEL-echoes is a consequence of the nearly zero E-layer rectilinear aspect angles in a region 5–10° poleward of the radar site. The F-layer echoes are probably the boundary blob echoes. The UHF EISCAT radar was in operation and observed a similar subvisual auroral arc and an F-layer electron density enhancement when it appeared in its antenna beam.

    Key words: Ionsophere (ionospheric irregularities · Magnetospheric physics (auroral phenomena; magnetosphere–ionosphere interactions

  11. 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.

  12. REMPI Spectroscopy of HfF

    CERN Document Server

    Loh, Huanqian; Yahn, Tyler S; Looser, Herbert; Field, Robert W; Cornell, Eric A

    2012-01-01

    The spectrum of electronic states at 30000--33000 cm$^{-1}$ in hafnium fluoride has been studied using (1+1) resonance-enhanced multi-photon ionization (REMPI) and (1+1$'$) REMPI. Six $\\Omega' = 3/2$ and ten $\\Pi_{1/2}$ vibronic bands have been characterized. We report the molecular constants for these bands and estimate the electronic energies of the excited states using a correction derived from the observed isotope shifts. When either of two closely spaced $\\Pi_{1/2}$ electronic states is used as an intermediate state to access autoionizing Rydberg levels, qualitatively distinct autoionization spectra are observed. The intermediate state-specificity of the autoionization spectra bodes well for the possibility of using a selected $\\Pi_{1/2}$ state as an intermediate state to create ionic HfF$^+$ in various selected quantum states, an important requirement for our electron electric dipole moment (eEDM) search in HfF$^+$.

  13. Digitally Driven Antenna for HF Transmission

    Science.gov (United States)

    2010-09-01

    the 1-MHz carrier signal. This signal is then fed into the base terminals of an NPN/ PNP transistor pair arranged in a push–pull configura- tion. A dual...negative voltage connected to the collector terminal of the PNP transistor . Since it was not possible to explicitly simulate the radia- tion of the time...complementary pair of switching transistors is driven with a pulsewidth modulated HF signal, eliminating the requirement for a frequency-dependent

  14. 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.

  15. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  16. Simulation of Controller Pilot Data Link Communications over VHF Digital Link Mode 3

    Science.gov (United States)

    Bretmersky, Steven C.; Murawski, Robert; Nguyen, Thanh C.; Raghavan, Rajesh S.

    2004-01-01

    The Federal Aviation Administration (FAA) has established an operational plan for the future Air Traffic Management (ATM) system, in which the Controller Pilot Data Link Communications (CPDLC) is envisioned to evolve into digital messaging that will take on an ever increasing role in controller to pilot communications, significantly changing the way the National Airspace System (NAS) is operating. According to FAA, CPDLC represents the first phase of the transition from the current analog voice system to an International Civil Aviation Organization (ICAO) compliant system in which digital communication becomes the alternate and perhaps primary method of routine communication. The CPDLC application is an Air Traffic Service (ATS) application in which pilots and controllers exchange messages via an addressed data link. CPDLC includes a set of clearance, information, and request message elements that correspond to existing phraseology employed by current Air Traffic Control (ATC) procedures. These message elements encompass altitude assignments, crossing constraints, lateral deviations, route changes and clearances, speed assignments, radio frequency assignments, and various requests for information. The pilot is provided with the capability to respond to messages, to request clearances and information, to report information, and to declare/rescind an emergency. A 'free text' capability is also provided to exchange information not conforming to defined formats. This paper presents simulated results of the aeronautical telecommunication application Controller Pilot Data Link Communications over VHF Digital Link Mode 3 (VDL Mode 3). The objective of this simulation study was to determine the impact of CPDLC traffic loads, in terms of timely message delivery and capacity of the VDL Mode 3 subnetwork. The traffic model is based on and is used for generating air/ground messages with different priorities. Communication is modeled for the en route domain of the Cleveland

  17. Effect of solar and magnetic activity on VHF scintillations near the equatorial anomaly crest

    Directory of Open Access Journals (Sweden)

    R. P. Singh

    2004-09-01

    Full Text Available The VHF amplitude scintillation recorded during the period January 1991 to December 1993 in the declining phase of a solar cycle and April 1998 to December 1999 in the ascending phase of the next solar cycle at Varanasi (geogr. lat.=25.3°, long.=83.0°, dip=37°N have been analyzed to study the behavior of ionospheric irregularities during active solar periods and magnetic storms. It is shown that irregularities occur at arbitrary times and may last for <30min. A rise in solar activity increases scintillations during winter (November-February and near equinoxes (March-April; September-October, whereas it depresses the scintillations during the summer (May-July. In general, the role of magnetic activity is to suppress scintillations in the pre-midnight period and to increase it in the post-midnight period during equinox and winter seasons, whilst during summer months the effect is reversed. The pre-midnight scintillation is sometimes observed when the main phase of Dst corresponds to the pre-midnight period. The annual variation shows suppression of scintillations on disturbed days, both during pre-midnight and post-midnight period, which becomes more effective during years of high solar activity. It is observed that for magnetic storms for which the recovery phase starts post-midnight, the probability of occurrence of irregularities is enhanced during this time. If the magnetic storm occurred during daytime, then the probability of occurrence of scintillations during the night hours is decreased. The penetration of magnetospheric electric fields to the magnetic equator affects the evolution of low-latitude irregularities. A delayed disturbance dynamo electric field also affects the development of irregularities.

  18. SUBSTRATE EFFECT ON HYDROGENATED MICROCRYSTALLINE SILICON FILMS DEPOSITED WITH VHF-PECVD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    H.D. Yang

    2006-01-01

    Raman spectra and scanning electron microscope (SEM) techniques were used to determine the structural properties of microcrystalline silicon (μc-Si:H) films deposited on different substrates with the very high frequency plasma-enhanced chemical vapor deposition ( VHF-PECVD )technique. Using the Raman spectra, the values of crystalline volume fraction Xc and average grain size d are 86%, 12.3nm; 65%, 5.45nm; and 38%, 4.05nm, for single crystalline silicon wafer,corning 7059 glass, and general optical glass substrates, respectively. The SEM images further demonstrate the substrate effect on the film surface roughness. For the single crystalline silicon wafer and Corning 7059 glass, the surfaces of the μc-Si:H films are fairly smooth because of the homogenous growth or little lattice mismatch. But for general optical glass, the surface of the μc-Si:H film is very rough, thus the growing surface roughness affects the crystallization process and determines the average grain size of the deposited material. Moreover, with the measurements of thickness, photo and dark conductivity, photosensitivity and activation energy, the substrate effect on the deposition rate, optical and electrical properties of the μc-Si:H thin films have also been investigated. On the basis of the above results, it can be concluded that the substrates affect the initial growing layers acting as a seed for the formation of a crystalline-like material, and then the deposition rates, optical and electrical properties are also strongly influenced, hence,deposition parameter optimization is the key method that can be used to obtain a good initial growing layer, to realize the deposition of μc-Si:H films with device-grade quality on cheap substrates such as general glass.

  19. The first time observations of low-latitude ionospheric irregularities by VHF radar in Hainan

    Institute of Scientific and Technical Information of China (English)

    NING BaiQi; HU LianHuan; LI GuoZhu; LIU LiBo; WAN WeiXing

    2012-01-01

    Sanya VHF radar (18.4°N,109.6°E,dip latitude 12.8°N) at Hainan Island is the first coherent backscatter radar for sounding low-latitude ionospheric irregularities in the mainland of China.In this paper,we present the first results of low-latitude ionospheric E and F region irregularities using the radar data during the period from February 2009 to March 2010.The Doppler velocity of radar echoes from E region field aligned irregularities (FAIs) was about several tens of meters per second,while the Doppler spectral width was appreciably larger than the velocity,and could reach one hundred meters per second,indicating that the observed E region FAIs belonged to type 2 irregularities.The observations of range time intensity (RTI) maps of FAIs showed that E region irregularities most often occurred at night within the altitude range 85-115 km,and were rarely observed at afternoon hours.The percentage occurrence of E region FAIs maximized during spring months (Feb.-May) with a peak value over 80%.The heights at which the strongest echo related FAIs occurred were mainly around 100 km,lower than h'Es and the difference is mostly 10-20 km.December solstice seemed to be the minimum period of occurrence when the FAI echoes were commonly detected at a narrow altitude range 90-100 km.Moreover,simultaneous radar and GPS observations during spread F events in the pre-midnight hours of solar minimum revealed that significant GPS L band scintillations coincided with the appearance of F region plasma plume structures,which extended up to 450 km in altitude.

  20. VHF radar observations of turbulent structures in the polar mesopause region

    Directory of Open Access Journals (Sweden)

    P. Czechowsky

    Full Text Available The mobile SOUSY VHF Radar was operated in the summer of 1987 during the MAC/SINE campaign in northern Norway to study the polar mesosphere summer echoes (PMSE. Measurements of the spectral width indicate that two types of structures occur. In general mesospheric layers are bifurcated exhibiting a narrow spectral width and a well-defined aspect sensitivity. However, for about 10% of the observation time cells of enhanced turbulence characterized by extremely broad spectral widths appear predominantly in the upper sublayer above 86 km. Identification and separation of beam and shear broadening allows a determination of the turbulence-induced component of the spectral width. This case study reveals that during several events these cloud-like structures of enhanced turbulence move with an apparent velocity of several tens of meters per second which is almost identical with the phase trace velocity of simultaneously observed waves. Since, at that time, the Richardson number was less than a quarter, it was concluded that these turbulent cells were generated by a Kelvin-Helmholtz mechanism. The horizontal extent of these structures was calculated to be less than 40 km. A general relation between spectral width and echo power was not detected. The turbulent component of the spectral width was used to calculate typical values of the energy dissipation rate at times where narrow spectral width dominates and during periods of enhanced turbulence. In addition, the outer scale of the inertial subrange (buoyancy scale was estimated. For the first time the occurrence and motion of this type of structures of enhanced spectral width is analyzed and discussed in detail.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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。

  6. Improvements on Signal Processing for HF Radar

    Institute of Scientific and Technical Information of China (English)

    LIU Yongtan; SHEN Yiying

    2001-01-01

    In this paper improvements on signalprocessing are achieved to enhance the performancesof H-F radar system, being unobtainable by the con-ventional signal processing. Using the improved sig-nal processing both high range resolution and longcoherent integration time may be obtained for goodbenefit to the target resolution and weak signal de-tection. Modification to the unmatched correspon-dence between range delay samples and range resolu-tion ceils saves an additional accumulation loss in therange processing. Finally, comparisons between theimproved and the conventional signal processing aregiven by numerical simulation.

  7. RF radiation observations of positive cloud-to-ground flashes

    Science.gov (United States)

    Shao, X. M.; Rhodes, C. T.; Holden, D. N.

    1999-04-01

    During the summers of 1995 and 1996 we conducted broadband HF-UHF and narrowband VHF radio frequency (RF) observations of positive cloud-to-ground (+CG) flashes at Langmuir and Los Alamos laboratories, New Mexico. These observations indicate that positive leaders to ground produce no or very weak radiation from HF to UHF. The broadband system was able to record 2 ms data each time it was triggered. For a +CG the system was usually triggered by the return stroke, and a 1 ms pretrigger period was coincident with the positive leader process. It was commonly observed that no or little radiation was associated with the leader process in the 1 ms pretrigger period. The narrowband VHF system employed a logarithmic power amplifier and recorded one 1 s data each time it was triggered. The narrowband observations show that strong and often continuous radiation occurs at the beginning of the +CGs, but the radiation usually becomes intermittent and impulsive during the last few tens of milliseconds preceding the return strokes. The observations for most of the +CGs also show complete lack of radiation a few ms before the beginning of the return strokes, suggesting that the ongoing downward positive leaders were quiet at VHF, at least during the final few ms. The results of this study for natural positive leaders are in agreement with the results obtained from laboratory gap discharges and rocket-triggered lightning.

  8. Systematic Study on Triaxial Superdeformed Bands of Hf Isotopes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Da-Li; DING Bin-Gang

    2009-01-01

    Properties of the triaxial superdeformed (TSD) bands of Hf isotopes are investigated systematically within the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry. Quantitatively good results of the γ-ray energies, the dynamical moments of inertia,and the spin of the TSD bands in Hf isotopes are obtained. It shows that this approach is quite powerful in describing the properties of the triaxial superdeformation in Hf isotopes.

  9. Determining Energy Distributions of HF-Accelerated Electrons at HAARP

    Science.gov (United States)

    2015-11-18

    AFRL-AFOSR-VA-TR-2015-0383 Determining energy distributions of HF-accelerated electrons at HAARP Christopher Fallen University of Alaska Fairbanks...2012 - 11/14/2015 4. TITLE AND SUBTITLE Determining energy distributions of HF-accelerated electrons at HAARP 5a. CONTRACT NUMBER FA9550-12-1-0424...transmitted from the High-frequency Active Auroral Research Program ( HAARP ) transmitter in Alaska. For a given fixed HF-plasma interaction altitude

  10. Physics of the Geospace Response to Powerful HF Radio Waves

    Science.gov (United States)

    2012-10-31

    studies of the response of the Earth’s space plasma to high-power HF radio waves from the High-frequency Active Auroral Research Program ( HAARP ...of HF heating and explored to simulate artificial ducts. DMSP- HAARP experiments revealed that HF-created ion outflows and artificial density ducts...in the topside ionosphere appeared faster than predicted by the models, pointing to kinetic (suprathermal) effects. CHAMP/GRACE- HAARP experiments

  11. Investigation of low-latitude ionospheric irregularities and their relationship to equatorial plasma bubbles using Sanya VHF radar

    Science.gov (United States)

    Ning, B.; Li, G.; Hu, L.

    2011-12-01

    A VHF radar has been set up at Sanya (18.34° N, 109.62° E, geomagnetic latitude 7.04°N), China in 2009. On the basis of the E, valley and F region irregularity observations detected by the Sanya VHF radar during equinoctial months, we focus on the simultaneous observations of E region irregularities disruption and valley region irregularities generation during the presence of post-sunset F region bubble structures. We stress that both the low latitude the E region irregularities (ERI) disruption and valley region irregularities (VRI) generation are associated with the development of post-sunset equatorial plasma bubble (EPB) structures. It is suggested that the electric field coupling from the unstable equatorial F region to low-latitude E and valley region could trigger and inhibit the occurrence of irregularities, depending on the polarity of the polarization electric field associated with the bifurcation of equatorial plasma bubbles. The mapping of upward/eastward and downward/eastward electric field associated with the west-tilted and east-tilted bubble structures, may be responsible for the disruption of E region irregularities, and the generation of valley region irregularities, respectively. However, more observations from multi instruments will be required to confirm such a scenario that the multi bifurcated EPBs play crucial roles for the simultaneous occurrence of low latitude ERI disruption and VRI generation.

  12. Effect of silane flow rate on structural, electrical and optical properties of silicon thin films grown by VHF PECVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Gope, Jhuma [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumar, Sushil, E-mail: skumar@nplindia.org [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Sudhakar, S.; Rauthan, C.M.S. [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, P.C. [Department of Physics, Banaras Hindu University, Varanasi 221005 (India)

    2013-08-15

    Hydrogenated silicon thin films deposited by VHF PECVD process for various silane flow rates have been investigated. The silane flow rate was varied from 5 sccm to 30 sccm, maintaining all other parameters constant. The electrical, structural and optical properties of these films were systematically studied as a function of silane flow rate. These films were characterized by Raman spectroscopy, Scanning Electron Microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and UV–visible (UV–Vis) spectroscopy. Different crystalline volume fraction (22%–60%) and band gap (∼1.58 eV–∼1.96 eV) were achieved for silicon thin films by varying the silane concentration. A transition from amorphous to nanocrystalline silicon has been confirmed by Raman and FTIR analysis. The film grown at this transition region shows the high conductivity in the order of 10{sup −4} Ω{sup −1} cm{sup −1}. - Highlights: • Silicon films grown using VHF PECVD at various F{sub silane} (silane flow rate). • Amorphous to nanocrystalline silicon transition at F{sub silane} ∼5 sccm–10 sccm. • Deposition rate increases with the increase of F{sub silane}. • Powder formation occurred beyond 20 sccm of F{sub silane}. • Film grown at 20 sccm shows max. crystalline fraction ∼60% with E{sub g} ∼1.58 eV.

  13. Radar efficiency and the calculation of decade-long PMSE backscatter cross-section for the Resolute Bay VHF radar

    Directory of Open Access Journals (Sweden)

    N. Swarnalingam

    2009-04-01

    Full Text Available The Resolute Bay VHF radar, located in Nunavut, Canada (75.0° N, 95.0° W and operating at 51.5 MHz, has been used to investigate Polar Mesosphere Summer Echoes (PMSE since 1997. PMSE are a unique form of strong coherent radar echoes, and their understanding has been a challenge to the scientific community since their discovery more than three decades ago. While other high latitude radars have recorded strong levels of PMSE activities, the Resolute Bay radar has observed relatively lower levels of PMSE strengths. In order to derive absolute measurements of PMSE strength at this site, a technique is developed to determine the radar efficiency using cosmic (sky noise variations along with the help of a calibrated noise source. VHF radars are only rarely calibrated, but determination of efficiency is even less common. Here we emphasize the importance of efficiency for determination of cross-section measurements. The significant advantage of this method is that it can be directly applied to any MST radar system anywhere in the world as long as the sky noise variations are known. The radar efficiencies for two on-site radars at Resolute Bay are determined. PMSE backscatter cross-section is estimated, and decade-long PMSE strength variations at this location are investigated. It was noticed that the median of the backscatter cross-section distribution remains relatively unchanged, but over the years a great level of variability occurs in the high power tail of the distribution.

  14. 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.

  15. An electronically tuned wideband probehead for NQR spectroscopy in the VHF range

    Science.gov (United States)

    Scharfetter, Hermann

    2016-10-01

    Nuclear quadrupole resonance spectroscopy is an analytical method which allows to characterize materials which contain quadrupolar nuclei, i.e. nuclei with spin ⩾1. The measurement technology is similar to that of NMR except that no static magnetic field is necessary. In contrast to NMR, however, it is frequently necessary to scan spectra with a very large bandwidth with a span of several tens of % of the central frequency so as to localize unknown peaks. Standard NMR probeheads which are typically constructed as resonators must be tuned and matched to comparatively narrow bands and must thus be re-tuned and re-matched very frequently when scanning over a whole NQR spectrum. At low frequencies up to few MHz dedicated circuits without the need for tuning and matching have been developed, but many quadrupole nuclei have transitions in the VHF range between several tens of MHz up to several hundreds of MHz. Currently available commercial NQR probeheads employ stepper motors for setting mechanically tuneable capacitors in standard NMR resonators. These yield high quality factors (Q) and thus high SNR but are relatively large and clumsy and do not allow for fast frequency sweeps. This article presents a new concept for a NQR probehead which combines a previously published no-tune no-match wideband concept for the transmit (TX) pulse with an electronically tuneable receive (RX) part employing varactor diodes. The prototype coil provides a TX frequency range of 57 MHz with a center frequency of 97.5 MHz with a return loss of ⩽-15 dB. During RX the resonator is tuned and matched automatically to the right frequency via control voltages which are read out from a previously generated lookup table, thus providing high SNR. The control voltages which bias the varactors settle very fast and allow for hopping to the next frequency point in the spectrum within less than 100 μs. Experiments with a test sample of ZnBr2 proved the feasibility of the method.

  16. PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKAN MIXER SETTLER

    Directory of Open Access Journals (Sweden)

    Dwi Biyantoro

    2017-01-01

    Full Text Available ABSTRAK PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKANMIXER SETTLER. Telah dilakukan pemisahanZr – Hf secara sinambung menggunakan pengaduk pengenap (mixer settler 16 stage. Larutan umpan adalah zirkon nitrat dengan kadar Zr = 30786 ppm dan Hf = 499 ppm. Ekstraktan dipakai adalah solven 60 % TBP dalam kerosen dan larutan scrubbingyang dipakai adalah asam nitrat 1 M. Umpan masuk pada stageke 5 dikontakkan secara berlawanan arah dengan solven masuk pada stage ke 16 dan larutan scrubbing masuk pada stage ke 1. Tujuan penelitian ini adalah memisahkan unsur Zr dan Hf dari hasil olah pasir zirkon menggunakan solven TBP dengan alat mixer settler16 stage. Analisis umpan dan hasil proses pemisahan untuk zirkonium (Zr dilakukan dengan menggunakan alat pendar sinar-X, sedangkananalisis unsur hafnium (Hf menggunakan Analisis Pengaktifan Neutron (APN. Parameter penelitian dilakukan dengan variasi keasaman asam nitrat dalam umpan dan variasi waktu pada berbagai laju pengadukan. Hasil penelitian pemisahan unsur Zr dengan Hf diperolehkondisi optimum pada keasaman umpan 4 N HNO3, keseimbangan dicapai setelah 3jam dan laju pengadukan 3300 rpm. Hasil ekstrak  unsur zirkon (Zr diperoleh kadar sebesar 28577 ppm dengan efisiensi 92,76 % serta kadar pengotor hafnium (Hf sebesar 95 ppm. Kata Kunci: pemisahan Zr, Hf, ekstraksi, mixer settler, alat pendar sinar-X, APN. ABSTRACT SEPARATION of Zr - Hf CONTINUOUSLY USE THE MIXER SETTLER. Separation of Zr - Hf continuously using mixer settler 16 stage has been done. The feed solution is zircon nitrate concentration of Zr = 30786 ppm  and Hf = 499 ppm. As the solvent used extractant 60 % TBP in 40 % kerosene. Nitric acid solution used srubbing 1 M. The feed entered into stage to 5 is contacted with solvents direction on the stage to 16 and the scrubbing solution enter the stage to 1. The purpose of this study is to separate Zr and Hf of the results from the process of zircon sand using solvent TBP using 16 stage

  17. Mitigating Doppler shift effect in HF multitone data modem

    Science.gov (United States)

    Sonlu, Yasar

    1989-09-01

    Digital communications over High Frequency (HF) radio channels are getting important in recent years. Current HF requirements are for data transmission at rates 2.4 kbps or more to accommodate computer data links and digital secure voice. HF modems which were produced to meet these speeds are, serial modems and parallel modems. On the other hand, the HF sky-wave communication medium, the ionosphere, has some propagation problems such as multipath and Doppler shift. The effect of Doppler shift in a parallel modem which employs Differential Quadrature Phase Shift Keying (DQPSK) modulation is considered and a correction method to mitigate the Doppler Shift effect is introduced.

  18. Epitaxial Thin Films of Y doped HfO2

    Science.gov (United States)

    Serrao, Claudy; Khan, Asif; Ramamoorthy, Ramesh; Salahuddin, Sayeef

    Hafnium oxide (HfO2) is one of a few metal oxides that is thermodynamically stable on silicon and silicon oxide. There has been renewed interest in HfO2 due to the recent discovery of ferroelectricity and antiferroelectricity in doped HfO2. Typical ferroelectrics - such as strontium bismuth tantalate (SBT) and lead zirconium titanate (PZT) - contain elements that easily react with silicon and silicon oxide at elevated temperatures; therefore, such ferroelectrics are not suited for device applications. Meanwhile, ferroelectric HfO2 offers promise regarding integration with silicon. The stable phase of HfO2 at room temperature is monoclinic, but HfO2 can be stabilized in the tetragonal, orthorhombic or even cubic phase by suitable doping. We stabilized Y-doped HfO2 thin films using pulsed laser deposition. The strain state can be controlled using various perovskite substrates and controlled growth conditions. We report on Y-doped HfO2 domain structures from piezo-response force microscopy (PFM) and structural parameters via X-ray reciprocal space maps (RSM). We hope this work spurs further interest in strain-tuned ferroelectricity in doped HfO2.

  19. Microstructural characterization of as-cast hf-b alloys

    Directory of Open Access Journals (Sweden)

    João Carlos Jânio Gigolotti

    2012-04-01

    Full Text Available An accurate knowledge of several metal-boron phase diagrams is important to evaluation of higher order systems such as metal-silicon-boron ternaries. The refinement and reassessment of phase diagram data is a continuous work, thus the reevaluation of metal-boron systems provides the possibility to confirm previous data from an investigation using higher purity materials and better analytical techniques. This work presents results of rigorous microstructural characterization of as-cast hafnium-boron alloys which are significant to assess the liquid composition associated to most of the invariant reactions of this system. Alloys were prepared by arc melting high purity hafnium (minimum 99.8% and boron (minimum 99.5% slices under argon atmosphere in water-cooled copper crucible with non consumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy, using back-scattered electron image mode and X-ray diffraction. In general, a good agreement was found between our data and those from the currently accepted Hafnium-Boron phase diagram. The phases identified are αHfSS and B-RhomSS, the intermediate compounds HfB and HfB2 and the liquide L. The reactions are the eutectic L ⇔ αHfSS + HfB and L ⇔ HfB2 + B-Rhom, the peritectic L + HfB2 ⇔ HfB and the congruent formation of HfB2.

  20. A DFT study of temperature dependent dissociation mechanism of HF in HF(H2O)7 cluster

    Indian Academy of Sciences (India)

    Swatantra K Yadav; Hirdyesh Mishra; Ashwani K Tiwari

    2015-10-01

    We report a Density Functional Theoretical (DFT) study of dissociation of Hydrogen Fluoride (HF) in HF(H2O)7 cluster, using B3LYP functional and empirical exchange correlation functional M06-2X along with 6-31+G(d,p) basis set. Dissociation constant, KRP, of HF dissociation and pKa values of HF in cluster at various temperatures have been reported. It has been found that both KRP and pKa are highly dependent on temperature. The variation of pKa with temperature suggests that HF is strong acid at lower temperatures. Our study also reveals that HF is a stronger acid in water cluster than in bulk water. Further, the results obtained by DFT calculations have been compared with the earlier reported results obtained from Monte Carlo (MC) simulation. It is found that DFT results are qualitatively consistent with the results of MC simulation but quantitatively different.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. Hf-W chronometry of primitive achondrites

    Science.gov (United States)

    Schulz, T.; Münker, C.; Mezger, K.; Palme, H.

    2010-03-01

    Metal segregation and silicate melting on asteroids are the most incisive differentiation events in the early evolution of planetary bodies. The timing of these events can be constrained using the short-lived 182Hf- 182W radionuclide system. Here we present new 182Hf- 182W data for major types of primitive achondrites including acapulcoites, winonaites and one lodranite. These meteorites are of particular interest because they show only limited evidence for partial melting of silicates and are therefore intermediate between chondrites and achondrites. For acapulcoites we derived a 182Hf- 182W age of Δ tCAI = 4.1 +1.2/ -1.1 Ma. A model age for winonaite separates calculated from the intercept of the isochron defines an age of Δ tCAI = 4.8 +3.1/ -2.6 Ma (assuming a bulk Hf/W ratio of ˜1.2). Both ages most likely define primary magmatic events on the respective parent bodies, such as melting of metal, although metal stayed in place and did not segregate to form a core. A later thermal event is responsible for resetting of the winonaite isochron, yielding an age of Δ tCAI = 14.3 +2.7/ -2.2 Ma, significantly younger than the model age. Assuming a co-genetic relationship between winonaites and silicates present in IAB iron meteorites (based on oxygen isotope composition) and including data by Schulz et al. (2009), a common parent body chronology can be established. Magmatic activity occurred between ˜1.5 and 5 Ma after CAIs. More than 5 Ma later, intensive thermal metamorphism has redistributed Hf-W. Average cooling rates calculated for the winonaite/IAB parent asteroid range between ˜35 and ˜4 K/Ma, most likely reflecting different burial depths. Cooling rates obtained for acapulcoites were ˜40 K/Ma to ˜720 K and then ˜3 K/Ma to ˜550 K. Accretion and subsequent magmatism on the acapulcoite parent body occurred slightly later if compared to most achondrite parent bodies (e.g., angrites, ureilites and eucrites), in this case supporting the concept of an inverse

  6. Pressure induced novel compounds in the Hf-O system from first-principles calculations

    OpenAIRE

    2015-01-01

    Using first-principles evolutionary simulations, we have systematically investigated phase stability in the Hf-O system at pressure up to 120 GPa. New compounds Hf5O2, Hf3O2, HfO and HfO3 are discovered to be thermodynamically stable at certain pressure ranges and a new stable high-pressure phase is found for Hf2O with space group Pnnm and anti-CaCl2-type structure. Both P62m-HfO and P4m2-Hf2O3 show semimetallic character. Pnnm-HfO3 shows interesting structure, simultaneously containing oxide...

  7. Ferroelectricity of nondoped thin HfO2 films in TiN/HfO2/TiN stacks

    Science.gov (United States)

    Nishimura, Tomonori; Xu, Lun; Shibayama, Shigehisa; Yajima, Takeaki; Migita, Shinji; Toriumi, Akira

    2016-08-01

    We report on the impact of TiN interfaces on the ferroelectricity of nondoped HfO2. Ferroelectric properties of nondoped HfO2 in TiN/HfO2/TiN stacks are shown in capacitance-voltage and polarization-voltage characteristics. The Curie temperature is also estimated to be around 500 °C. The ferroelectricity of nondoped HfO2 clearly appears by thinning HfO2 film down to ˜35 nm. We directly revealed in thermal treatments that the ferroelectric HfO2 film on TiN was maintained by covering the top surface of HfO2 with TiN, while it was followed by a phase transition to the paraelectric phase in the case of the open surface of HfO2. Thus, it is concluded that the ferroelectricity in nondoped HfO2 in this study was mainly driven by both of top and bottom TiN interfaces.

  8. High-Rate Fabrication of a-Si-Based Thin-Film Solar Cells Using Large-Area VHF PECVD Processes

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xunming [University of Toledo; Fan, Qi Hua

    2011-12-31

    The University of Toledo (UT), working in concert with it’s a-Si-based PV industry partner Xunlight Corporation (Xunlight), has conducted a comprehensive study to develop a large-area (3ft x 3ft) VHF PECVD system for high rate uniform fabrication of silicon absorber layers, and the large-area VHF PECVD processes to achieve high performance a-Si/a-SiGe or a-Si/nc-Si tandem junction solar cells during the period of July 1, 2008 to Dec. 31, 2011, under DOE Award No. DE-FG36-08GO18073. The project had two primary goals: (i) to develop and improve a large area (3 ft × 3 ft) VHF PECVD system for high rate fabrication of > = 8 Å/s a-Si and >= 20 Å/s nc-Si or 4 Å/s a-SiGe absorber layers with high uniformity in film thicknesses and in material structures. (ii) to develop and optimize the large-area VHF PECVD processes to achieve high-performance a-Si/nc-Si or a-Si/a-SiGe tandem-junction solar cells with >= 10% stable efficiency. Our work has met the goals and is summarized in “Accomplishments versus goals and objectives”.

  9. A three dimensional study of E region irregularity patches in the equatorial anomaly region using the Chung-Li VHF radar

    Energy Technology Data Exchange (ETDEWEB)

    Pan, C.J.; Liu, C.H.; Su, S.Y. [National Central Univ., Taiwan (China); Roettger, J. [EISCAT Scientific Association, Kiruna (Sweden)

    1994-08-15

    The authors report on VHF radar observations of E region Field Aligned Irregularity patches made from Taiwan. They observe pancake shaped patches, smaller than the radar viewing width. They are seen at heights above 100 km, drifting with velocities slightly less than 100 m/s.

  10. Synthesis of Freestanding HfO2 Nanostructures

    Science.gov (United States)

    2011-04-05

    Tang J, Fabbri J, Robinson RD, Zhu Y, Herman IP, Steigerwald ML, Brus LE: Solid-solution nanoparticles:use of a nonhydrolytic sol-gel synthesis to...colloidal HfO2 nanorods. Adv Mater 2007, 19:2608-2612. Page 21 5. Qiu X, Howe JY, Cardoso MB, Polat O, Heller W: Size control of highly ordered HfO2

  11. Parametric excitation of whistler waves by HF heater

    Science.gov (United States)

    Kuo, S. P.; Lee, M. C.

    1989-01-01

    Possible generation of whistler waves by Tromso HF heater is investigated. It is shown that the HF heater wave can parametrically decay into a whistler wave and a Langmuir wave. Since whistler waves may have a broad range of frequency, the simultaneously excited Langmuir waves can have a much broader frequency bandwidth than those excited by the parametric decay instability.

  12. Study of {sup 179}Hf{sup m2} excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vishnevsky, I. N.; Zheltonozhsky, V. A., E-mail: zhelton@kinr.kiev.ua; Savrasov, A. N. [National Academy of Sciences of Ukraine, Institute for Nuclear Research (Ukraine); Mazur, V. M. [National Academy of Sciences of Ukraine, Institute of Electronic Physics (Ukraine)

    2016-12-15

    Isomeric ratios of {sup 179}Hf{sup m2,g} yields in the (γ, n) reaction and the cross section for the {sup 179}Hf{sup m2} population in the (α, p) reaction are measured for the first time at the end-point energies of 15.1 and 17.5 MeV for bremsstrahlung photons and 26 MeV for alpha particles. The results are σ = (1.1 ± 0.11) × 10{sup −27} cm{sup 2} for the {sup 176}Lu(α, p){sup 179}Hf{sup m2} reaction and Y{sub m2}/Y{sub g} = (6.1 ± 0.3) × 10{sup −6} and (3.7 ± 0.2) × 10{sup −6} for the {sup 180}Hf(γ, n){sup 179}Hf{sup m22} reaction at E{sub ep} =15.1 and 17.5 MeV, respectively. The experimental data on the relative {sup 179}Hf{sup m2} yield indicate a single-humped shape of the excitation function for the {sup 180}Hf(γ, n){sup 179}Hf{sup m2} reaction. Simulation is performed using the TALYS-1.4 and EMPIRE-3.2 codes.

  13. Diffusion of Hf and Nb in Zr-19%Nb

    Energy Technology Data Exchange (ETDEWEB)

    Zou, H. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Hood, G.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Schultz, R.J. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Matsuura, N. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Roy, J.A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Jackman, J.A. [CANMET, Ottawa, Ont. (Canada). Met. Sci. and Technol.

    1996-05-01

    Diffusion of Hf and Nb in large-grained bcc Zr-19%Nb has been studied. Diffusion coefficients of Hf, D(Hf), were measured in the range 620-1173 K and D(Nb) was measured at 920 and 1167 K. The Hf diffusion profiles were determined by SIMS and the Nb profiles by microtome sectioning and radio-tracer counting. The Hf data show a smooth, temperature-dependent behaviour through the monotectoid temperature, 875 K, and may be characterised by D{approx}10{sup -9}.exp-1.4 (eV/kT) m{sup 2}/s. D(Nb) tends to be lower than the corresponding values for D(Hf). Overall, diffusion of Hf and Nb are characteristic of diffusion in bcc Zr. Surface hold-up (oxide film) at low temperatures was overcome by using ion-implanted Hf diffusion sources. The results are compared with earlier work and discussed in terms of diffusion mechanisms and the {beta}-phase transformation of commercial Zr-2.5Nb. (orig.).

  14. Oxygen Recovery in Hf Oxide Films Fabricated by Sputtering

    Institute of Scientific and Technical Information of China (English)

    JIANG Ran; LI Zi-Feng

    2009-01-01

    The chemical structure of ultrathin Hf oxide films (< 10 nm) fabricated by a standard sputtering method is investigated using x-ray spectroscopy and Rutherford backscattering spectroscopy. According to the experiments,oxygen species are impacted to the HfO2/Si interface during the initial sputtering, and then released back to the upper Hf02 region driven by the oxygen concentration grads. A vacuum annealing can greatly enhance this recovery process. Additionally, significant SiO2 reduction in the interface is observed after the vacuum annealing for the thick HfO2 films in our experiment. It might be an effective method to confine the interracial layer thickness by sputtering thick HfO2 in no-oxygen ambient.

  15. Crystal structure of Si-doped HfO2

    Science.gov (United States)

    Zhao, Lili; Nelson, Matthew; Aldridge, Henry; Iamsasri, Thanakorn; Fancher, Chris M.; Forrester, Jennifer S.; Nishida, Toshikazu; Moghaddam, Saeed; Jones, Jacob L.

    2014-01-01

    Si-doped HfO2 was prepared by solid state synthesis of the starting oxides. Using Rietveld refinement of high resolution X-ray diffraction patterns, a substitutional limit of Si in HfO2 was determined as less than 9 at. %. A second phase was identified as Cristobalite (SiO2) rather than HfSiO4, the latter of which would be expected from existing SiO2-HfO2 phase diagrams. Crystallographic refinement with increased Si-dopant concentration in monoclinic HfO2 shows that c/b increases, while β decreases. The spontaneous strain, which characterizes the ferroelastic distortion of the unit cell, was calculated and shown to decrease with increasing Si substitution.

  16. The (178m2)Hf Controversy

    Energy Technology Data Exchange (ETDEWEB)

    Becker, J A; Gemmell, D S; Schiffer, J P; Wilhelmy, J B

    2003-07-24

    Since its discovery in the 1960's the {sup 178m2}Hf isomer has garnered high attention from both the basic and applied communities in nuclear science. It's combination of high spin (16+), long half life (31 yrs), and high excitation energy (2.446 MeV) offer unique possibilities as an energy storage medium. Interest in the isomer was rekindled beginning in 1999 when a series of publications began to appear from a group (referred to here as the ''Texas collaboration'') primarily based at the University of Texas, Dallas [1]. They reported observations that some of the stored energy could be released (''triggered'') when the isomer was exposed to a fluence of photons in the energy range {approx}10 to {approx}60 keV. The implications of this observation are profound. Even though the claimed cross section for the process was {approx}7 orders of magnitude greater than would be predicted from the known systematics of photon absorption by nuclei in this mass range [2], such a highly efficient method for triggering the isomeric deexcitation immediately suggested applications utilizing the explosive or the controlled gradual energy release from a very compact source. The prospect of such applications has focused considerable interest on realizing the promise that is implicit in the reported observations. However, two experiments performed by a group from ANL/LANL/LLNL at the Advanced Photon Source at Argonne (the ''APS collaboration'') reported negative results for the observation of any photon-triggered deexcitation of the {sup 178m2}Hf isomer [3]. This has led to a continued controversy, where both sides have adamantly defended their observations. At this point an outsider has difficulty determining whether there is indeed a triggering effect that should be pursued energetically with substantial resources, or whether the phenomenon consists of overly optimistic interpretation of data.

  17. Geolocation of RF signals

    CERN Document Server

    Progri, Ilir

    2011-01-01

    ""Geolocation of RF Signals - Principles and Simulations"" offers an overview of the best practices and innovative techniques in the art and science of geolocation over the last twenty years. It covers all research and development aspects including theoretical analysis, RF signals, geolocation techniques, key block diagrams, and practical principle simulation examples in the frequency band from 100 MHz to 18 GHz or even 60 GHz. Starting with RF signals, the book progressively examines various signal bands - such as VLF, LF, MF, HF, VHF, UHF, L, S, C, X, Ku, and, K and the corresponding geoloca

  18. Electromagnetics and Antenna Technology. Chapters 1, 2, 3

    Science.gov (United States)

    2017-01-12

    defined by the Institute for Electronic and Electrical Engineers ( IEEE ). The IEEE definitions of the HF and VHF bands are the same as the ITU definition...that is, 3 to 30 MHz and 30 to 300 MHz, respectively. The IEEE definition of UHF is from 300 MHz to 1 GHz, L band is from 1 to 2 GHz, S band is from...line. Copyright: IEEE [106] • With a series inductor, the impedance rotates clockwise along circles of constant resistance on the impedance (Z-type

  19. Propuesta de una red nacional de alerta para sucesos de clima espacial basado en receptores SDR de bajo coste

    OpenAIRE

    Mascareñas y Pérez-Iñigo, Carlos

    2014-01-01

    Un documento de trabajo que trata sobre el diseño de una red de alerta temprana sobre sucesos de meteorología espacial ¿Qué son receptores SDR de Bajo Coste? Antecedentes Inicio de la Radioastronomía. K. Jansky y G. Reber. E-Callisto. Websdr. Tipos de Receptores SDR. ELF-HF. VHF-UHF. Convertidores. Aplicaciones de los receptores SDR. Monitorización de frecuencias. Análisis de Espectros. Detección de Meteoritos y Aeronaves. Propuesta d...

  20. 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

  1. The study of the substrate temperature depended growth properties of microcrystalline silicon films deposited by VHF-PECVD method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongsheng, E-mail: chysh2003@zzu.edu.cn [Key Lab of Material Physics, Department of Physics, Zhengzhou University, Zhengzhou 450052 (China); Chen, Xiping; Hao, Xiuli; Lu, Jingxiao; Yang, Shi-e [Key Lab of Material Physics, Department of Physics, Zhengzhou University, Zhengzhou 450052 (China)

    2013-04-01

    In this paper, we have measured the temperature depended growth properties of hydrogenated microcrystalline silicon (μc-Si:H) films, prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) from SiH{sub 4} and H{sub 2} gas mixtures. And, a 1D plasma model coupled with a well-mixed reactor model is used to simulate the growth process, in which concentrations of gas phase species, the crystalline orientation, the hydrogen content and the deposition rate are calculated. It suggests that the increasing surface fraction of the dangling bonds with the increase of substrate temperatures is responsible for the increase in the grain sizes. At the same time, the observed variations of the X-ray-diffraction intensities and the deposition rates of the films with temperature result from the differences in the growth rates of the facets.

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

    Directory of Open Access Journals (Sweden)

    E. Kolesnikova

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

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

  3. First observations of electron gyro-harmonic effects under X-mode HF pumping the high latitude ionospheric F-region

    Science.gov (United States)

    Blagoveshchenskaya, N. F.; Borisova, T. D.; Kalishin, A. S.; Yeoman, T. K.; Häggström, I.

    2017-03-01

    We provide the first experimental evidence of the sensitivity of phenomena induced by extraordinary (X-mode) polarized HF high power radio waves to pump frequency stepping across the fifth electron gyro-harmonic (5fce) from below to above. The results were obtained at the EISCAT (European Incoherent Scatter Scientific Association) HF heater facility near Tromsø under effective radiated powers of 456-715 MW, when the HF pump wave was transmitted into the magnetic zenith. We have analyzed the behavior and intensities of various spectral lines in the narrowband stimulated electromagnetic emission (SEE) spectra observed far from the heater, HF-enhanced plasma and ion lines (HFPL and HFIL) from EISCAT UHF incoherent scatter radar spectra, and artificial field-aligned irregularities from CUTLASS (Co-operative UK Twin Located Auroral Sounding System) observations, depending on the frequency offset of the pump field relative to the 5fce. At pump frequencies below 5fce the narrowband SEE spectra exhibited very intense so-called stimulated ion Bernstein scatter (SIBS), accompanied by other spectral components, associated with stimulated Brillouin scatter (SBS), which are greatly suppressed and disappeared in the vicinity of 5fce and did not reappear at fH>5fce. As the pump frequency reached 5fce, the abrupt enhancements of the HFPL and HFIL power, the appearance of cascade lines in the plasma line spectra, and the onset of increasing CUTLASS backscatter power occurred. That is opposite to the ordinary mode (O-mode) effects in the vicinity of 5fce. The X-mode pumping at frequencies below and in the vicinity of the fifth electron gyro-harmonic clearly demonstrated an ascending altitude of generation of induced plasma and ion lines from the initial interaction height, whereas for O-mode heating the region of interaction descended. The observations are consistent with the coexistence of the electron acceleration along and across the geomagnetic field at fH<5fce, while only very

  4. Ferroelectricity-modulated resistive switching in Pt/Si:HfO2/HfO2-x /Pt memory

    Science.gov (United States)

    Ran, Jiang; Xianghao, Du; Zuyin, Han

    2016-08-01

    It is investigated for the effect of a ferroelectric Si:HfO2 thin film on the resistive switching in a stacked Pt/Si:HfO2/highly-oxygen-deficient HfO2-x /Pt structure. Improved resistance performance was observed. It was concluded that the observed resistive switching behavior was related to the modulation of the width and height of a depletion barrier in the HfO2-x layer, which was caused by the Si:HfO2 ferroelectric polarization field effect. Reliable switching reproducibility and long data retention were observed in these memory cells, suggesting their great potential in non-volatile memories applications with full compatibility and simplicity. Project supported by the National Natural Science Foundation of China (No. 11374182), the Natural Science Foundation of Shandong Province (No. ZR2012FQ012), and the Jinan Independent Innovation Projects of Universities (No. 201303019).

  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. First observations of Kelvin-Helmholtz billows in an upper level jet stream using VHF frequency domain interferometry

    Science.gov (United States)

    Chilson, Phillip B.; Muschinski, Andreas; Schmidt, Gerhard

    1997-05-01

    In this paper we report the first high-resolution observations of upper tropospheric Kelvin-Helmholtz billows using VHF frequency domain interferometry (FDI). The measurements were made using the sounding system VHF radar located in the German Harz Mountains operating at the frequencies of 53.25 and 53.75 MHz. Through an application of the FDI technique it has been possible to track the altitude of thin scattering layers with an accuracy of a few tens of meters and a temporal resolution of 13 s. Taking advantage of the FDI technique, we found several examples of Kelvin-Helmholtz instability (KHI) in regions coinciding with large values of wind shear. One particularly good example is presented in detail. The KHI occurred just below the axis of the jet at an altitude of 9.1 km. It produced oscillations in the vertical velocity field in the altitude range of 8-10 km. The oscillations had a local period of 90 s and persisted over a time interval of 10 min. On the basis of the magnitude of the horizontal wind at the time and height of the KHI, the billow train had a horizontal extent of about 27 km, while the horizontal length of the individual billow amounted to about 4.0 km. The 90-s oscillations were also observed in the radar signal power, the FDI-derived layer height, and the coherence between the received radar signals for the two frequencies. Using the FDI data, we were able to identify the individual billows located within the train and observe their maximum crest-to-trough amplitudes to be between 220 and 230 m. This was less than the conventional radar resolution of 300 m used during the experiment.

  7. 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。

  8. 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.

  9. 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.

  10. Power-Stepped HF Cross Modulation Experiments at HAARP

    Science.gov (United States)

    Greene, S.; Moore, R. C.; Langston, J. S.

    2013-12-01

    High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. In this paper, we apply experimental observations of HF cross-modulation to the related problem of ELF/VLF wave generation. HF cross-modulation measurements are used to evaluate the efficiency of ionospheric conductivity modulation during power-stepped modulated HF heating experiments. The results are compared to previously published dependencies of ELF/VLF wave amplitude on HF peak power. The experiments were performed during the March 2013 campaign at the High Frequency Active Auroral Research Program (HAARP) Observatory. HAARP was operated in a dual-beam transmission format: the first beam heated the ionosphere using sinusoidal amplitude modulation while the second beam broadcast a series of low-power probe pulses. The peak power of the modulating beam was incremented in 1-dB steps. We compare the minimum and maximum cross-modulation effect and the amplitude of the resulting cross-modulation waveform to the expected power-law dependence of ELF/VLF wave amplitude on HF power.

  11. 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

  12. HF dissociation in water clusters by computer simulations

    OpenAIRE

    Elena, Alin Marin

    2013-01-01

    We perform Restrained hybrid Monte Carlo simulations to compute the equilibrium constant of the dissociation reaction of HF in HF(H2O)7. We find that, like in the bulk, hydrofluoric acid, is a weak acid also in the cubic HF(H2O)7 cluster, and that its acidity is higher at lower T. This latter phenomenon has a (vibrational) entropic origin, namely it is due to the reduction of the (negative) T∆S contribution to the variation of free energy between the reactant and product. We found also ...

  13. Ionospheric heating with oblique HF waves

    Science.gov (United States)

    Field, Edward C., Jr.; Bloom, Ron M.

    1990-10-01

    Calculations of ionospheric electron density perturbations and ground-level signal changes produce by intense oblique high frequency (HF) transmitters are presented. This analysis considers radio field focusing at caustics, the consequent joule-heating of the surrounding plasma, heat conduction, diffusion, and recombination processes: these being the effects of a powerful oblique 'modifying' wave. It neglects whatever plasma instabilities might occur. Then effects on a secondary 'test' wave that is propagated along the same path as the first are investigated. Calculations predict ground-level field-strength reductions of several dB in the test wave for modifying waves having ERP in the 85 to 90 dBW range. These field-strength changes are similar in sign, magnitude, and location to ones measured in Soviet experiments. The results are sensitive to the model ionosphere assumed, so future experiments should employ the widest possible range of frequencies and propagation conditions. An effective power of 90 dBW seems to be a sort of threshold that, if exceeded, results in substantial rather than small signal changes. The conclusions are based solely on joule-heating and subsequent defocusing of waves passing through caustic regions.

  14. Process Simulation Analysis of HF Stripping

    Directory of Open Access Journals (Sweden)

    Thaer A. Abdulla

    2013-05-01

    Full Text Available    HYSYS process simulator is used for the analysis of existing HF stripping column in LAB plant (Arab Detergent Company, Baiji-Iraq. Simulated column performance and profiles curves are constructed. The variables considered are the thermodynamic model option, bottom temperature, feed temperature, and column profiles for the temperature, vapor flow rate, liquid flow rate and composition. The five thermodynamic models options used (Margules, UNIQUAC, van laar, Antoine, and Zudkevitch-Joffee, affecting the results within (0.1-58% variation for the most cases.        The simulated results show that about 4% of paraffin (C10 & C11 presents at the top stream, which may cause a problem in the LAB production plant. The major variations were noticed for the total top vapor flow rate with bottom temperature and with feed composition. The column profiles maintain fairly constants from tray 5 to tray 18. The study gives evidence about a successful simulation with HYSYS because the results correspond with the real plant operation data.

  15. The (178m2) Hf Controversy

    CERN Document Server

    Becker, J A; Schiffer, J P; Wilhelmy, J

    2003-01-01

    Since its discovery in the 1960's the sup 1 sup 7 sup 8 sup m sup 2 Hf isomer has garnered high attention from both the basic and applied communities in nuclear science. It's combination of high spin (16+), long half life (31 yrs), and high excitation energy (2.446 MeV) offer unique possibilities as an energy storage medium. Interest in the isomer was rekindled beginning in 1999 when a series of publications began to appear from a group (referred to here as the ''Texas collaboration'') primarily based at the University of Texas, Dallas [1]. They reported observations that some of the stored energy could be released (''triggered'') when the isomer was exposed to a fluence of photons in the energy range approx 10 to approx 60 keV. The implications of this observation are profound. Even though the claimed cross section for the process was approx 7 orders of magnitude greater than would be predicted from the known systematics of photon absorption by nuclei in this mass range [2], such a highly efficient method fo...

  16. Grindability of cast Ti-Hf alloys.

    Science.gov (United States)

    Kikuchi, Masafumi; Takahashi, Masatoshi; Sato, Hideki; Okuno, Osamu; Nunn, Martha E; Okabe, Toru

    2006-04-01

    As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

  17. The magnetic properties of $^{\\rm 177}$Hf and $^{\\rm 180}$Hf in the strong coupling deformed model

    OpenAIRE

    Muto, S.; Stone, N. J.; Bingham, C. R.; STONE, J.R; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.(Institut Laue-Langevin (ILL), Grenoble, France); Nikolov, J.; Nishimura,K; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G.S.; Veskovic, M.

    2014-01-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\\rm 180}$Hf by the method of on-line nuclear orientation. Also included are results on the angular distributions of gamma transitions in the decay of the $^{\\rm 177}$Hf isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2$^+$, 1.1 s, isomer at 1315 keV ...

  18. A thirty second isomer in {sup 171}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, P.; Billowes, J.; Cooper, T.G.; Grant, I.S.; Pearson, M.R.; Wheeler, P.D. [Schuster Laboratory, University of Manchester, M13 9PL (United Kingdom); Cochrane, E.C.A.; Cooke, J.L.; Evans, D.E.; Griffith, J.A.R.; Persson, J.R.; Richardson, D.S.; Tungate, G.; Zybert, L. [School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Dendooven, P.; Honkanen, A.; Huhta, M.; Oinonen, M.; Penttilae, H.; Aeystoe, J. [Accelerator Laboratory, University of Jyvaeskylae, PL 35 Jyvaeskylae SF-403 51 (Finland)

    1997-09-01

    An isomer has been detected in {sup 171}Hf with a half-life of T{sub 1/2} 29.5(9) s. The state was populated in the {sup 170}Yb({alpha},3n){sup 171m}Hf reaction at a beam energy of E{sub {alpha}} = 50 MeV in an on-line ion guide isotope separator. The isomeric {sup 171m}Hf{sup +} beam was extracted from the ion guide, mass-analysed and implanted in the surface of a microchannel-plate. The half-life of the collected activity was measured from the decay of the microchannel-plate count rate. We associate the isomer with the first excited state in {sup 171}Hf with spin 1/2{sup -} at an excitation energy of 22(2) keV. (author)

  19. HF fiber stuffing in building 186 at CERN

    CERN Multimedia

    Tiziano Camporesi

    2003-01-01

    Each of the 36 HF wedges comprise ca 12000 quartz fibers which are the active element of the calorimeter. The fibers are produced by Polymicro (USA), cleaved and bundled at KFKI, Budapest, Hungary and inserted at CERN.

  20. Low-Frequency Waves in HF Heating of the Ionosphere

    Science.gov (United States)

    Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

    2016-02-01

    Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

  1. Near-infrared LIF spectroscopy of HfF

    CERN Document Server

    Grau, Matt; Loh, Huanqian; Sinclair, Laura C; Stutz, Russel P; Yahn, Tylser S; Cornell, Eric A

    2012-01-01

    The molecular ion HfF$^+$ is the chosen species for a JILA experiment to measure the electron electric dipole moment (eEDM). Detailed knowledge of the spectrum of HfF is crucial to prepare HfF$^+$ in a state suitable for performing an eEDM measurement\\cite{Leanhardt}. We investigated the near-infrared electronic spectrum of HfF using laser-induced fluorescence (LIF) of a supersonic molecular beam. We discovered eight unreported bands, and assign each of them unambiguously, four to vibrational bands belonging to the transition $[13.8]0.5 \\leftarrow X1.5$, and four to vibrational bands belonging to the transition $[14.2]1.5 \\leftarrow X1.5$. Additionally, we report an improved measurement of vibrational spacing of the ground state, as well as anharmonicity $\\omega_e x_e$.

  2. Theoretical Assessment of 178m2Hf De-Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hartouni, E P; Chen, M; Descalle, M A; Escher, J E; Loshak, A; Navratil, P; Ormand, W E; Pruet, J; Thompson, I J; Wang, T F

    2008-10-06

    This document contains a comprehensive literature review in support of the theoretical assessment of the {sup 178m2}Hf de-excitation, as well as a rigorous description of controlled energy release from an isomeric nuclear state.

  3. 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.

  4. 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).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Integrated magnetics design for HF-link power converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the integrated magnetic components do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation...... of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs....

  11. Integrated magnetics design for HF-link power converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the two integrated magnetic components on the same core do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs. (au)

  12. Synthesis of freestanding HfO2 nanostructures

    Directory of Open Access Journals (Sweden)

    Boyle Kayla

    2011-01-01

    Full Text Available Abstract Two new methods for synthesizing nanostructured HfO2 have been developed. The first method entails exposing HfTe2 powders to air. This simple process resulted in the formation of nanometer scale crystallites of HfO2. The second method involved a two-step heating process by which macroscopic, freestanding nanosheets of HfO2 were formed as a byproduct during the synthesis of HfTe2. These highly two-dimensional sheets had side lengths measuring up to several millimeters and were stable enough to be manipulated with tweezers and other instruments. The thickness of the sheets ranged from a few to a few hundred nanometers. The thinnest sheets appeared transparent when viewed in a scanning electron microscope. It was found that the presence of Mn enhanced the formation of HfO2 by exposure to ambient conditions and was necessary for the formation of the large scale nanosheets. These results present new routes to create freestanding nanostructured hafnium dioxide. PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

  13. The isobutylene-isobutane alkylation process in liquid HF revisited.

    Science.gov (United States)

    Esteves, P M; Araújo, C L; Horta, B A C; Alvarez, L J; Zicovich-Wilson, C M; Ramírez-Solís, A

    2005-07-07

    Details on the mechanism of HF catalyzed isobutylene-isobutane alkylation were investigated. On the basis of available experimental data and high-level quantum chemical calculations, a detailed reaction mechanism is proposed taking into account solvation effects of the medium. On the basis of our computational results, we explain why the density of the liquid media and stirring rates are the most important parameters to achieve maximum yield of alkylate, in agreement with experimental findings. The ab initio Car-Parrinello molecular dynamics calculations show that isobutylene is irreversibly protonated in the liquid HF medium at higher densities, leading to the ion pair formation, which is shown to be a minimum on the potential energy surface after optimization using periodic boundary conditions. The HF medium solvates preferentially the fluoride anion, which is found as solvated [FHF](-) or solvated F(-.)(HF)(3). On the other hand, the tert-butyl cation is weakly solvated, where the closest HF molecules appear at a distance of about 2.9 Angstrom with the fluorine termination of an HF chain.

  14. Hf impurity and defect interactions in helium-implanted NiHf

    Energy Technology Data Exchange (ETDEWEB)

    Govindaraj, R. E-mail: govind@igcar.ernet.in; Gopinathan, K.P.; Viswanathan, B

    2001-07-01

    TDPAC measurements on the reference and untreated sample indicate a loss in anisotropy which is attributed mainly to the association of probe atoms with defects produced by (n,{gamma}) reactions with isotopes of Ni and experiencing combined magnetic and quadrupole interactions of comparable strengths. Evolution of defect free and substitutional fraction of probe atoms experiencing Larmor frequency characteristic of Ni matrix has been studied as a function of isochronal annealing temperature in helium free {alpha}-irradiated and homogeneously helium-implanted samples. No defect associated Larmor precession frequency and/or quadrupole frequency could be deduced in these uncorrelated damage studies. Comparison of recovery stages in {alpha}-irradiated and helium-implanted samples indicates the binding of helium associated defects by Hf impurities. Segregation of Hf atoms is observed in the helium free {alpha}-irradiated sample for annealing treatment at 973 K, while no such effect is observed in the helium-implanted sample for isochronal annealing treatments up to 1273 K.

  15. Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

    Science.gov (United States)

    Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

    2017-09-01

    The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

  16. Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada

    Science.gov (United States)

    Lowery, Claiborne L.E.; Miller, C.F.; Walker, B.A.; Wooden, J.L.; Mazdab, F.K.; Bea, F.

    2006-01-01

    Zirconium and Hf are nearly identical geochemically, and therefore most of the crust maintains near-chondritic Zr/Hf ratios of ???35-40. By contrast, many high-silica rhyolites and granites have anomalously low Zr/Hf (15-30). As zircon is the primary reservoir for both Zr and Hf and preferentially incorporates Zr, crystallization of zircon controls Zr/ Hf, imprinting low Zr/Hf on coexisting melt. Thus, low Zr/Hf is a unique fingerprint of effective magmatic fractionation in the crust. Age and compositional zonation in zircons themselves provide a record of the thermal and compositional histories of magmatic systems. High Hf (low Zr/ Hf) in zircon zones demonstrates growth from fractionated melt, and Ti provides an estimate of temperature of crystallization (TTiZ) (Watson and Harrison, 2005). Whole-rock Zr/Hf and zircon zonation in the Spirit Mountain batholith, Nevada, document repeated fractionation and thermal fluctuations. Ratios of Zr/Hf are ???30-40 for cumulates and 18-30 for high-SiO2 granites. In zircons, Hf (and U) are inversely correlated with Ti, and concentrations indicate large fluctuations in melt composition and TTiZ (>100??C) for individual zircons. Such variations are consistent with field relations and ion-probe zircon geochronology that indicate a >1 million year history of repeated replenishment, fractionation, and extraction of melt from crystal mush to form the low Zr/Hf high-SiO2 zone. ?? 2006 The Mineralogical Society.

  17. 通用超短波跳频电台的研究与实现%Research and Implementation of General VHF FH Radio

    Institute of Scientific and Technical Information of China (English)

    李胜峰

    2012-01-01

    VHF frequency-hopping communications in the international most advanced technology was undoubtedly the U.S.defense and military communications technology,VHF frequency hopping radio is widely used in countries in military fields.Class radio is also widely used for commercial,especially in the consortium or multinational corporations,in order to guarantee the security of the information.This paper describes the basic principles of frequency hopping communication around the VHF frequency hopping radio system requirements,program design and the analysis and gives radio engineering program.%在国际上超短波跳频通信最先进的技术当属美国国防军事通信技术,超短波跳频电台在各国军用领域使用广泛,该类电台目前也开始广泛用于商业、特别是在用于各财团或跨国公司,以保证信息的安全。该文阐述了跳频通信基本原理,围绕超短波跳频电台系统的需求、方案设计等问题做了相应的分析,并给出电台的工程实现方案。

  18. The Epi Info Viral Hemorrhagic Fever (VHF) Application: A Resource for Outbreak Data Management and Contact Tracing in the 2014-2016 West Africa Ebola Epidemic.

    Science.gov (United States)

    Schafer, Ilana J; Knudsen, Erik; McNamara, Lucy A; Agnihotri, Sachin; Rollin, Pierre E; Islam, Asad

    2016-10-15

    The Epi Info Viral Hemorrhagic Fever application (Epi Info VHF) was developed in response to challenges managing outbreak data during four 2012 filovirus outbreaks. Development goals included combining case and contact data in a relational database, facilitating data-driven contact tracing, and improving outbreak data consistency and use. The application was first deployed in Guinea, when the West Africa Ebola epidemic was detected, in March 2014, and has been used in 7 African countries and 2 US states. Epi Info VHF enabled reporting of compatible data from multiple countries, contributing to international Ebola knowledge. However, challenges were encountered in accommodating the epidemic's unexpectedly large magnitude, addressing country-specific needs within 1 software product, and using the application in settings with limited Internet access and information technology support. Use of Epi Info VHF in the West Africa Ebola epidemic highlighted the fundamental importance of good data management for effective outbreak response, regardless of the software used. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  19. Determination of isothermal section of Ni-Re-Hf ternary system at 1173 K

    Institute of Scientific and Technical Information of China (English)

    王日初; 柳春雷; 金展鹏

    2002-01-01

    The phase equilibriua in the Ni-Re-Hf ternary system at 1173K were investigated by means of diffusion triple technique and electron microprobe analysis(EMPA). The experimental results indicate that two ternary intermetallics (α and β) and five binary intermetallics (Ni3Hf, Ni10Hf7, Ni11Hf9, NiHf and NiHf2) exist in the Ni-Re-Hf system at 1173 K. A tentative isothermal section of this system at 1173 K was constructed on the basis of experimental results. The isothermal section consists of nine three-phase regions, five of which are supported by the experimental data.

  20. VHF SoOp (Signal of Opportunity) Technology Demonstration for Soil Moisture Measurement Using Microwave Hydraulic Boom Truck Platform

    Science.gov (United States)

    Joseph, Alicia; Deshpande, Manohar; O'Neill, Peggy; Miles, Lynn

    2017-04-01

    A goal of this research is to test deployable VHF antennas for 6U Cubesat platforms to enable validation of root zone soil moisture (RZSM) estimation algorithms for signal of opportunity (SoOp) remote sensing over the 240-270 MHz frequency band. The proposed work provides a strong foundation for establishing a technology development path for maturing a global direct surface soil moisture (SM) and RZSM measurement system over a variety of land covers. Knowledge of RZSM up to a depth of 1 meter and surface SM up to a depth of 0.05 meter on a global scale, at a spatial resolution of 1-10 km through moderate-to-heavy vegetation, is critical to understanding global water resources and the vertical moisture gradient in the Earth's surface layer which controls moisture interactions between the soil, vegetation, and atmosphere. Current observations of surface SM from space by L-band radiometers (1.4 GHz) and radars (1.26 GHz) are limited to measurements of surface SM up to a depth of 0.05 meter through moderate amounts of vegetation. This limitation is mainly due to the inability of L-band signals to penetrate through dense vegetation and deep into the soil column. Satellite observations of the surface moisture conditions are coupled to sophisticated models which extrapolate the surface SM into the root zone, thus providing an indirect estimate rather than a direct measurement of RZSM. To overcome this limitation, low-frequency airborne radars operating at 435 MHz and 118 MHz have been investigated, since these lower frequencies should penetrate denser vegetation and respond to conditions deeper in the soil. This presentation describes a new and less expensive technique for SM as well as RZSM direct measurement using Signal of Opportunity transmitters. Being less expensive and needing only passive simple RF receiver, the SoOp concept has the potential for being used for space borne applications, thus providing global SM and RZSM measurements. This study will describe

  1. Network Management System for Tactical Mobile Ad Hoc Network Segments

    Science.gov (United States)

    2011-09-01

    Protocol UFO UHF Follow-On UHF Ultra High Frequency USB Universal Serial Bus VHF Very High Frequency VIRT Valuable Information at the Right Time...military satellite system known as the UHF Follow-on system ( UFO ) only provides capacity for 600 concurrent users. DoD users also have commercial

  2. Spallation and fission products in the (p+{sup 179}Hf) and (p+{sup nat}Hf) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Karamian, S.A. [Joint Institute for Nuclear Research, Moscow Region, Dubna 141980 (Russian Federation); Ur, C.A. [Horia Hulubei National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest 077125 (Romania); Induced Gamma Emission Foundation, P.O. Box 34-81, Bucharest 010044 (Romania)], E-mail: ur@pd.infn.it; Adam, J. [Joint Institute for Nuclear Research, Moscow Region, Dubna 141980 (Russian Federation); Institute of Nuclear Physics, Rez, Prague CZ-25068 (Czech Republic); Kalinnikov, V.G.; Lebedev, N.A.; Vostokin, G.K. [Joint Institute for Nuclear Research, Moscow Region, Dubna 141980 (Russian Federation); Collins, C.B. [Center for Quantum Electronics, University of Texas at Dallas, Richardson, TX 75083 (United States); Popescu, I.I. [Induced Gamma Emission Foundation, P.O. Box 34-81, Bucharest 010044 (Romania)

    2009-03-01

    Production of Hf and Lu high-spin isomers has been experimentally studied in spallation reactions induced by intermediate energy protons. Targets of enriched {sup 179}Hf (91%) and {sup nat}Hf were bombarded with protons of energy in the range from 90 to 650 MeV provided by the internal beam of the Dubna Phasotron synchrocyclotron. The activation yields of the reaction products were measured by using the {gamma}-ray spectroscopy and radiochemistry methods. The production cross-sections obtained for the {sup 179m2}Hf, {sup 178m2}Hf and {sup 177m}Lu isomers are similar to the previously measured values from the spallation of Ta, Re and W targets. Therefore, the reactions involving emission of only a few nucleons, like (p,p'), (p,p'n) and (p,2pn), can transfer high enough angular momentum to the final residual nuclei with reasonable large cross-sections. A significant gain in the isomeric yields was obtained when enriched {sup 179}Hf targets were used. The mass distribution of the residual nuclei was measured over a wide range of masses and the fission-to-spallation ratio could be deduced as a function of the projectile energy. Features of the reaction mechanism are briefly discussed.

  3. 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/℃.

  4. Hf-Nd isotope and trace element constraints on subduction inputs at island arcs: Limitations of Hf anomalies as sediment input indicators

    Science.gov (United States)

    Handley, Heather K.; Turner, Simon; Macpherson, Colin G.; Gertisser, Ralf; Davidson, Jon P.

    2011-04-01

    New Nd-Hf isotope and trace element data for Javanese volcanoes are combined with recently published data to place constraints on subduction inputs at the Sunda arc in Indonesia and assess the value of Hf anomalies (expressed as Hf/Hf* and Sm/Hf ratios) as tracers of such inputs. Hf anomaly does not correlate with Hf isotope ratio in Javanese lavas, however, Hf/Hf* and Sm/Hf ratios do correlate with SiO 2. Contrary to previous work, we show that Hf anomaly variation may be controlled by fractionation of clinopyroxene and/or amphibole during magmatic differentiation and does not represent the magnitude or type of subduction input in some arcs. Correlation of Sm/Hf with indices of differentiation for other arcs (e.g., Vanuatu, New Britain, and Mariana) suggests that differentiation control on Sm/Hf ratios in volcanic arc rocks may be a relatively common phenomenon. This study corroborates the use of Nd-Hf isotope co-variations in arc volcanic rocks to ascertain subduction input characteristics. The trajectories of regional volcano groups (East, Central and West Java) in Nd-Hf isotope space reveal heterogeneity in the subducted sediment input along Java, which reflects present-day spatial variations in sediment compositions on the down-going plate in the Java Trench. The high Sm/Hf ratio required in the sediment end-member for some Javanese basalts suggests that partial melting of subducted sediment occurs in the presence of residual zircon, and is inconsistent with residual monazite or allanite.

  5. Investigation and Development of Data-Driven D-Region Model for HF Systems Impacts

    Science.gov (United States)

    Eccles, J. V.; Rice, D.; Sojka, J. J.; Hunsucker, R. D.

    2002-01-01

    Space Environment Corporation (SEC) and RP Consultants (RPC) are to develop and validate a weather-capable D region model for making High Frequency (HF) absorption predictions in support of the HF communications and radar communities. The weather-capable model will assimilate solar and earth space observations from NASA satellites. The model will account for solar-induced impacts on HF absorption, including X-rays, Solar Proton Events (SPE's), and auroral precipitation. The work plan includes: I . Optimize D-region model to quickly obtain ion and electron densities for proper HF absorption calculations. 2. Develop indices-driven modules for D-region ionization sources for low, mid, & high latitudes including X-rays, cosmic rays, auroral precipitation, & solar protons. (Note: solar spectrum & auroral modules already exist). 3. Setup low-cost monitors of existing HF beacons and add one single-frequency beacon. 4. Use PENEX HF-link database with HF monitor data to validate D-region/HF absorption model using climatological ionization drivers. 5. Develop algorithms to assimilate NASA satellite data of solar, interplanetary, and auroral observations into ionization source modules. 6. Use PENEX HF-link & HF-beacon data for skill score comparison of assimilation versus climatological D-region/HF absorption model. Only some satellites are available for the PENEX time period, thus, HF-beacon data is necessary. 7. Use HF beacon monitors to develop HF-link data assimilation algorithms for regional improvement to the D-region/HF absorption model.

  6. Serpentinization Changes Nd, but not Hf Isotopes of Abyssal Peridotites

    Science.gov (United States)

    Bizimis, M.; Frisby, C. P.; Mallick, S.

    2015-12-01

    Serpentinization of the oceanic lithosphere is a known sink for fluid mobile elements (B, Cl, Li, Sr, etc.), while high field strength elements (HFSE: e.g., Hf, Zr, Ti, Nb) are thought to be unaffected by it. In contrast, the fate of REE during serpentinization is equivocal. Correlations between REE and HFSE concentrations in abyssal peridotites suggest control by magmatic processes (Niu, 2004, J. Pet), while some LREE enrichments in serpentinized peridotites compared to their clinopyroxene (cpx) and Nd, Sr isotope data (Delacour et al., 2008, Chem. Geol.) imply seawater-derived REE addition to the mantle protolith (Paulick et al., 2006, Chem. Geol). To further constrain peridotite-seawater interaction during serpentinization we compare bulk rock and cpx Hf and Nd isotope data in partially (up to ~70%) serpentinized abyssal peridotites (9-16°E South West Indian Ridge). We also present a new method that improves yields in Hf, Nd and Pb separations from depleted (90% of Hf, Zr, Ti are retained in the residue. LA-ICPMS data shows that serpentine after olivine typically has higher LREE/HREE ratios than cpx, pronounced negative Ce anomalies, high U, Sr concentrations and low HFSE, unlike the coexisting cpx. These data are consistent with some seawater-derived LREE addition to peridotite during serpentinization, localized in the serpentine and other secondary phases, while cpx retains the magmatic value. This process will lower the Sm/Nd relative to Lu/Hf ratio in the peridotite and can lead to decoupled radiogenic Hf and unradiogenic Nd isotopes upon recycling and aging. Our data further testifies to the fidelity of Hf isotopes in tracing mantle processes, even in serpentinized rocks.

  7. Joint Efforts Towards European HF Radar Integration

    Science.gov (United States)

    Rubio, A.; Mader, J.; Griffa, A.; Mantovani, C.; Corgnati, L.; Novellino, A.; Schulz-Stellenfleth, J.; Quentin, C.; Wyatt, L.; Ruiz, M. I.; Lorente, P.; Hartnett, M.; Gorringe, P.

    2016-12-01

    During the past two years, significant steps have been made in Europe for achieving the needed accessibility to High Frequency Radar (HFR) data for a pan-European use. Since 2015, EuroGOOS Ocean Observing Task Teams (TT), such as HFR TT, are operational networks of observing platforms. The main goal is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of HFR data access and tools. Particular attention is being paid by HFR TT to converge from different projects and programs toward those common objectives. First, JERICO-NEXT (Joint European Research Infrastructure network for Coastal Observatory - Novel European eXpertise for coastal observaTories, H2020 2015 Programme) will contribute on describing the status of the European network, on seeking harmonization through exchange of best practices and standardization, on developing and giving access to quality control procedures and new products, and finally on demonstrating the use of such technology in the general scientific strategy focused by the Coastal Observatory. Then, EMODnet (European Marine Observation and Data Network) Physics started to assemble HF radar metadata and data products within Europe in a uniform way. This long term program is providing a combined array of services and functionalities to users for obtaining free of charge data, meta-data and data products on the physical conditions of European sea basins and oceans. Additionally, the Copernicus Marine Environment Monitoring Service (CMEMS) delivers from 2015 a core information service to any user related to 4 areas of benefits: Maritime Safety, Coastal and Marine Environment, Marine Resources, and Weather, Seasonal Forecasting and Climate activities. INCREASE (Innovation and Networking for the integration of Coastal Radars into EuropeAn marine SErvices - CMEMS Service Evolution 2016) will set the necessary developments towards the integration of existing European

  8. First-principles study of the Hf-based Heusler alloys: Hf2CoGa and Hf2CoIn

    Science.gov (United States)

    Hu, Yan; Zhang, Jian-Min

    2017-01-01

    The electronic structures and magnetic properties of the new Heusler alloys Hf2CoGa and Hf2CoIn have been studied by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). Both Hf2CoGa and Hf2CoIn Heusler alloys have the half-metallic character and completely (100%) spin polarization at the Fermi level (EF) and the indirect band gaps of 0.733 eV and 0.654 eV, respectively, in the minority spin channel. The total magnetic moments μt are all 2μB per formula unit, linearly scaled with the total number of valence electrons (Zt) by μt=Zt-18 and the atomic magnetic moments have localized character due to less affected by deformations. The origin of the indirect band gaps for these two new Heusler alloys is well understood. These two new Heusler alloys are the ideal candidates for spintronic devices.

  9. Case study of stratospheric gravity waves of convective origin over Arctic Scandinavia – VHF radar observations and numerical modelling

    Directory of Open Access Journals (Sweden)

    A. Réchou

    2013-02-01

    Full Text Available Orography is a well-known source of gravity and inertia-gravity waves in the atmosphere. Other sources, such as convection, are also known to be potentially important but the large amplitude of orographic waves over Scandinavia has generally precluded the possibility to study such other sources experimentally in this region. In order to better understand the origin of stratospheric gravity waves observed by the VHF radar ESRAD (Esrange MST radar over Kiruna, in Arctic Sweden (67.88° N, 21.10° E, observations have been compared to simulations made using the Weather Research and Forecasting model (WRF with and without the effects of orography and clouds. This case study concerns gravity waves observed from 00:00 UTC on 18 February to 12:00 UTC on 20 February 2007. We focus on the wave signatures in the static stability field and vertical wind deduced from the simulations and from the observations as these are the parameters which are provided by the observations with the best height coverage. As is common at this site, orographic gravity waves were produced over the Scandinavian mountains and observed by the radar. However, at the same time, southward propagation of fronts in the Barents Sea created short-period waves which propagated into the stratosphere and were transported, embedded in the cyclonic winds, over the radar site.

  10. Characteristics of low latitude ionospheric E-region irregularities linked with daytime VHF scintillations measured from Varanasi

    Indian Academy of Sciences (India)

    K Patel; A K Singh; R P Patel; R P Singh

    2009-12-01

    VHF amplitude scintillations recorded during the daytime period from January 1991 to December 1993, April 1998 to December 1999 and January 2008 to December 2008 at low latitude station Varanasi (geographic lat. = 25° 15′N; long. = 82° 59′E; geomagnetic lat. = 14° 55′N, long. = 154°E, dip angle = 37.3°, sub-ionospheric dip = 34°) have been analyzed to study the behaviour of ionospheric E-region irregularities during the active solar and magnetic periods. The autocorrelation functions, power spectral densities, signal de-correlation times are computed to study the temporal features of ionospheric E-region irregularities linked with daytime scintillations. Derived spectral index ranges between −2 and −9. Assuming velocity of irregularities, the characteristic lengths of the E-region irregularities are estimated. We have estimated the minimum and maximum range of scale length of sporadic-E () irregularities to be observed over Varanasi. These results are in close agreement with those reported from this latitude region.

  11. Evolution of infrared spectra and optical emission spectra in hydrogenated silicon thin films prepared by VHF-PECVD

    Science.gov (United States)

    Hou, Guo-Fu; Geng, Xin-Hua; Zhang, Xiao-Dan; Sun, Jian; Zhang, Jian-Jun; Zhao, Ying

    2011-07-01

    A series of hydrogenated silicon thin films with varying silane concentrations have been deposited by using very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The deposition process and the silicon thin films are studied by using optical emission spectroscopy (OES) and Fourier transfer infrared (FTIR) spectroscopy, respectively. The results show that when the silane concentration changes from 10% to 1%, the peak frequency of the Si-H stretching mode shifts from 2000 cm-1 to 2100 cm-1, while the peak frequency of the Si—H wagging—rocking mode shifts from 650 cm-1 to 620 cm-1. At the same time the SiH/Hα intensity ratio in the plasma decreases gradually. The evolution of the infrared spectra and the optical emission spectra demonstrates a morphological phase transition from amorphous silicon (a-Si:H) to microcrystalline silicon (μc-Si:H). The structural evolution and the μc-Si:H formation have been analyzed based on the variation of Hα and SiH intensities in the plasma. The role of oxygen impurity during the plasma process and in the silicon films is also discussed in this study.

  12. Case study of stratospheric gravity waves of convective origin over Arctic Scandinavia. VHF radar observations and numerical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Rechou, A. [La Reunion Univ., St. Denis Messag, Ile de La Reunion (France). Lab. de l' Atmosphere et des Cyclones; Arnault, J.; Dalin, P.; Kirkwood, S. [Swedish Institute of Space Physics, Kiruna (Sweden)

    2013-03-01

    Orography is a well-known source of gravity and inertia-gravity waves in the atmosphere. Other sources, such as convection, are also known to be potentially important but the large amplitude of orographic waves over Scandinavia has generally precluded the possibility to study such other sources experimentally in this region. In order to better understand the origin of stratospheric gravity waves observed by the VHF radar ESRAD (Esrange MST radar) over Kiruna, in Arctic Sweden (67.88 N, 21.10 E), observations have been compared to simulations made using the Weather Research and Forecasting model (WRF) with and without the effects of orography and clouds. This case study concerns gravity waves observed from 00:00 UTC on 18 February to 12:00 UTC on 20 February 2007. We focus on the wave signatures in the static stability field and vertical wind deduced from the simulations and from the observations as these are the parameters which are provided by the observations with the best height coverage. As is common at this site, orographic gravity waves were produced over the Scandinavian mountains and observed by the radar. However, at the same time, southward propagation of fronts in the Barents Sea created short-period waves which propagated into the stratosphere and were transported, embedded in the cyclonic winds, over the radar site. (orig.)

  13. HF omnidirectional spectral CW auroral radar (HF-OSCAR) at very high latitude. Part 1: Technique

    Science.gov (United States)

    Olesen, J. K.; Jacobsen, K. E.; Stauning, P.; Henriksen, S.

    1983-12-01

    An HF system for studies of very high latitude ionospheric irregularities was described. Radio aurora from field-aligned E-region irregularities of the Slant E Condition type were discussed. The complete system combines an ionosonde, a 12 MHz pulse radar and a 12 MHz bistatic CW Doppler-range set-up. The two latter units use alternately a 360 deg rotating Yagi antenna. High precision oscillators secure the frequency stability of the Doppler system in which the received signal is mixed down to a center frequency of 500 Hz. The Doppler shift range is max + or - 500 Hz. The received signal is recorded in analog form on magnetic tape and may be monitored visually and audibly. Echo range of the CW Doppler signal is obtained by a 150 Hz amplitude modulation of the transmitted signal and phase comparison with the backscattered signal.

  14. Comparison of HfAlO, HfO2/Al2O3, and HfO2 on n-type GaAs using atomic layer deposition

    Science.gov (United States)

    Lu, Bin; Lv, Hongliang; Zhang, Yuming; Zhang, Yimen; Liu, Chen

    2016-11-01

    Different high-permittivity (high-k) gate dielectric structures of HfO2, HfAlO, and HfO2/Al2O3 deposited on HF-etched n-GaAs using ALD have been investigated. It has been demonstrated that the stacked structure of HfO2/Al2O3 has the lowest interface state density of 8.12 × 1012eV-1 cm-2 due to the "self-cleaning" reaction process, but the sample of HfAlO shows much better frequency dispersion and much higher dielectric permittivity extracted from the C-V curves. The investigation reveals that the electrical properties of gate dielectrics are improved by introducing alumina into HfO2.

  15. 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。

  16. Mechanical properties of cast Ti-Hf alloys.

    Science.gov (United States)

    Sato, Hideki; Kikuchi, Masafumi; Komatsu, Masashi; Okuno, Osamu; Okabe, Toru

    2005-02-15

    This study examined the mechanical properties of a series of Ti-Hf alloys. Titanium alloys with 10 to 40 mass % Hf were made with titanium and hafnium sponge in an argon-arc melting furnace. Specimens cast into magnesia-based investment molds were tested for yield strength, tensile strength, percentage elongation, and modulus of elasticity. Vickers microhardness was determined at 25 to 600 microm from the cast surface. X-ray diffractometry was also performed. Commercially pure Ti (CP Ti) and pure Ti prepared from titanium sponge were used as controls. The data (n = 5) were analyzed with a one-way ANOVA and the Student-Newman-Keuls test (alpha = 0.05). The diffraction peaks of all the metals matched those for alpha Ti; no beta phase peaks were found. Alloys with Hf > or = 25% had significantly (p 0.05) in elongation among all the Ti-Hf alloys and CP Ti, whereas the elongation of alloys with Hf > or = 30% was significantly (p alloys tested can be considered viable alternatives to CP Ti because they were stronger than CP Ti and had similar elongation.

  17. HfO2 Gate Dielectrics for Future Generation of CMOS Device Application

    Institute of Scientific and Technical Information of China (English)

    H.Y.Yu; J.F.Kang; Ren Chi; M.F.Li; D.L.Kwong

    2004-01-01

    The material and electrical properties of HfO2 high-k gate dielectric are reported.In the first part,the band alignment of HfO2 and (HfO2)x(Al2O3)1-x to (100)Si substrate and their thermal stability are studied by X-ray photoelectron spectroscopy and TEM.The energy gap of (HfO2)x(Al2O3)1-x,the valence band offset,and the conduction band offset between (HfO2)x(Al2O3)1-x and the Si substrate as functions of x are obtained based on the XPS results.Our XPS results also demonstrate that both the thermal stability and the resistance to oxygen diffusion of HfO2 are improved by adding Al to form Hf aluminates.In the second part,a thermally stable and high quality HfN/HfO2 gate stack is reported.Negligible changes in equivalent oxide thickness (EOT),gate leakage,and work function (close to Si mid-gap) of HfN/HfO2 gate stack are demonstrated even after 1000℃ post-metal annealing(PMA),which is attributed to the superior oxygen diffusion barrier of HfN as well as the thermal stability of the HfN/HfO2 interface.Therefore,even without surface nitridation prior to HfO2 deposition,the EOT of HfN/HfO2 gate stack has been successfully scaled down to less than 1nm after 1000℃ PMA with excellent leakage and long-term reliability.The last part demonstrates a novel replacement gate process employing a HfN dummy gate and sub-1nm EOT HfO2 gate dielectric.The excellent thermal stability of the HfN/HfO2 gate stack enables its use in high temperature CMOS processes.The replacement of HfN with other metal gate materials with work functions adequate for n- and p-MOS is facilitated by a high etch selectivity of HfN with respect to HfO2,without any degradation to the EOT,gate leakage,or TDDB characteristics of HfO2.

  18. Pressure-induced novel compounds in the Hf-O system from first-principles calculations

    Science.gov (United States)

    Zhang, Jin; Oganov, Artem R.; Li, Xinfeng; Xue, Kan-Hao; Wang, Zhenhai; Dong, Huafeng

    2015-11-01

    Using first-principles evolutionary simulations, we have systematically investigated phase stability in the Hf-O system at pressure up to 120 GPa. New compounds Hf5O2,Hf3O2 , HfO, and HfO3 are discovered to be thermodynamically stable at certain pressure ranges. Two new high-pressure phases are found for Hf2O : one with space group Pnnm and anti-CaCl2-type structure, another with space group I 41/amd. Pnnm-HfO3 shows interesting structure, simultaneously containing oxide O2 - and peroxide [O-O]2 - anions. Remarkably, it is P 6 ¯2 m -HfO rather than OII-HfO2 that exhibits the highest mechanical characteristics among Hf-O compounds. Pnnm-Hf2O , Imm2-Hf5O2 ,P 3 ¯1 m -Hf2O , and P 4 ¯m 2 -Hf2O3 phases also show superior mechanical properties; theoretically these phases become metastable phases to ambient pressure and their properties can be exploited.

  19. Effect of HF leaching on 14C dates of pottery

    Science.gov (United States)

    Goslar, Tomasz; Kozłowski, Janusz; Szmyt, Marzena; Czernik, Justyna

    2013-01-01

    This paper presents the experiments with 14C dating of two potsherds, which contained carbon dispersed rather homogeneously in their clay fabric. After AAA treatment, the potsherds still appeared to be contaminated with young carbon, presumably connected with humic acids. To make removal of humic acids more effective, we treated the sherds with HF acid of different concentration. The 14C results obtained demonstrate that HF treatment indeed helps to remove humic contaminants, but it also mobilizes carbon bound to raw clay, which may make 14C dates too old. We conclude therefore, that using a simple combination of HF and AAA treatment seems insufficient in reliable 14C dating of carbon homogeneously dispersed in the volume of potsherds.

  20. The Status of Rotational Nonequilibrium in HF Chemical Lasers

    Science.gov (United States)

    1986-05-01

    later study from the same laboratory, Copeland et al. 5 3 used a NdYAG dye laser to pump HF into v = 2, j, and an HF pulsed laser to probe various P 2(J... Weston , Jr., J. Chem. Phys. 77, 4776 (1982). 51. J. J. Hinchen and R. H. Hobbs, Appl. Phys. 50, 628 (1979). 52. j. K. Lambert, G. M. Jursich, and F. F...Crim, Chem. Phys. Lett. 71, 258 (1980). 53. R. A. Copeland , D. J. Pearson, and F. F. Crim, Chem. Phys. Lett. 81, 541 (1981). 54. T. J. Foster and F. F

  1. New active load voltage clamp for HF-link converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, M.A.E.

    2005-07-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core. (au)

  2. HF-induced airglow at magnetic zenith: theoretical considerations

    Directory of Open Access Journals (Sweden)

    E. V. Mishin

    2005-01-01

    Full Text Available Observations of airglow at 630nm (red line and 557.7nm (green line during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume are consistent with this scenario.

  3. HF-hash : Hash Functions Using Restricted HFE Challenge-1

    CERN Document Server

    Dey, Dhananjoy; Gupta, Indranath Sen

    2009-01-01

    Vulnerability of dedicated hash functions to various attacks has made the task of designing hash function much more challenging. This provides us a strong motivation to design a new cryptographic hash function viz. HF-hash. This is a hash function, whose compression function is designed by using first 32 polynomials of HFE Challenge-1 with 64 variables by forcing remaining 16 variables as zero. HF-hash gives 256 bits message digest and is as efficient as SHA-256. It is secure against the differential attack proposed by Chabaud and Joux as well as by Wang et. al. applied to SHA-0 and SHA-1.

  4. Hf--Co--B alloys as permanent magnet materials

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, Michael Alan; Rios, Orlando; Ghimire, Nirmal Jeevi

    2017-01-24

    An alloy composition is composed essentially of Hf.sub.2-XZr.sub.XCo.sub.11B.sub.Y, wherein 0Hf.sub.2-XZr.sub.XCo.sub.11B.sub.Y, wherein 0.ltoreq.X<2 and 0

  5. New active load voltage clamp for HF-link converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path du...... during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core....

  6. European coordination for coastal HF radar data in EMODnet Physics

    Science.gov (United States)

    Mader, Julien; Novellino, Antonio; Gorringe, Patrick; Griffa, Annalisa; Schulz-Stellenfleth, Johannes; Montero, Pedro; Montovani, Carlo; Ayensa, Garbi; Vila, Begoña; Rubio, Anna; Sagarminaga, Yolanda

    2015-04-01

    Historically, joint effort has been put on observing open ocean, organizing, homogenizing, sharing and reinforcing the impact of the acquired information based on one technology: ARGO with profilers Argo floats, EuroSites, ESONET-NoE, FixO3 for deep water platforms, Ferrybox for stations in ships of opportunities, and GROOM for the more recent gliders. This kind of networking creates synergies and makes easier the implementation of this source of data in the European Data exchange services like EMODnet, ROOSs portals, or any applied services in the Blue economy. One main targeted improvement in the second phase of EMODnet projects is the assembling of data along coastline. In that sense, further coordination is recommended between platform operators around a specific technology in order to make easier the implementation of the data in the platforms (4th EuroGOOS DATAMEQ WG). HF radar is today recognized internationally as a cost-effective solution to provide high spatial and temporal resolution current maps (depending on the instrument operation frequency, covering from a few kilometres offshore up to 200 km) that are needed for many applications for issues related to ocean surface drift or sea state characterization. Significant heterogeneity still exists in Europe concerning technological configurations, data processing, quality standards and data availability. This makes more difficult the development of a significant network for achieving the needed accessibility to HF Radar data for a pan European use. EuroGOOS took the initiative to lead and coordinate activities within the various observation platforms by establishing a number of Ocean Observing Task Teams such as HF-Radars. The purpose is to coordinate and join the technological, scientific and operational HF radar communities at European level. The goal of the group is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. OPTIMAL PREPARATION JUNCTIONS FOR ALL-CERAMIC FIXED RESTORATIONS MADE BY CAM 5 – S 2 IMPRESSION, VHF

    Directory of Open Access Journals (Sweden)

    Angelina Vlahova

    2015-12-01

    Full Text Available Introduction: The type of the preparation junction is determined by a number of factors that need to be taken in consideration with CAD/CAM Fixed Prosthodontics: the material of which the construction will be made; the type and condition of the retainer teeth, of their periodontium and the occlusion; the design software, the CAM setting and the type of drills; the working protocol; the type of the cement and the method of cementation.Purpose: The aim of this publication is to describe the optimal preparation junctions for all-ceramic crown and bridge restorations made by CAM 5 - S 2 Impression, VHF.Materials and methods: Suitable are chamfer and shoulder preparation junction with rounded inner angle (width 1 - 1, 5 mm. Trimming of 1.5 – 2 mm dental tissues is necessary on the occlusal surface. The homothetic reduction of teeth is optimal.Results and discussion: The width depends on the size and vitality of the tooth. In stained teeth and those built with metal pins the removal of more tissues provides a greater volume needed to disguise the dark color. Vestibular preparation under the level of the gingiva is preferable to ensure optimal aesthetics. Preparation junction is determined also by the CAD/CAM technology - the type of drills and protocol of impression taking (classical or digital. The creation of a working model with TRIOS, 3Shape intraoral scanner is greatly facilitated by preparation junctions made above the gingival margin.Conclusion: Knowledge about the criteria for selection the preparation junctions is essential for fabrication accurate and aesthetic CAD/CAM restorations.

  15. An Ultra Wideband VHF CMOS LC VCO%超宽频带VHF频段CMOS LC VCO

    Institute of Scientific and Technical Information of China (English)

    宁彦卿; 王志华; 陈弘毅

    2006-01-01

    This paper presents a VHF CMOS VCO. The most significant improvement on the VCO is that the cross-coupled MOSFET pairs are divided into several switchable parts so the characteristics can compensate the state change that results from the frequency tuning of the oscillator. This VCO is implemented in 0.18μm CMOS with a core area of about 550μm × 700μm. The test results show that the tuning range covers 31~111MHz with a power consumption between 0.3~6.9mW and a phase noise at a 100kHz offset of about - 110dBc/Hz.%实现了一个宽频带VHF频段CMOS VCO.其最大的改进在于将振荡器中交叉耦合MOS管分为并联可开关的若干段.这样使其特性可以在较大范围内补偿VCO调频过程中状态的变化.该VCO使用标准0.18μmCMOS工艺制作,核心版图面积约为550μm×700μm.测试结果表明:该VCO频率覆盖范围为31~111MHz;功耗为0.3~6.9mW;在100kHz频偏处相位噪声约-110dBc/Hz.

  16. VHF profiler observations of winds and waves in the troposphere during the Darwin Area Wave Experiment (DAWEX)

    Science.gov (United States)

    Vincent, R. A.; MacKinnon, A.; Reid, I. M.; Alexander, M. J.

    2004-10-01

    A VHF atmospheric radar (wind profiler) was used to study tropospheric winds during the Darwin Area Wave Experiment (DAWEX). The profiler, which operated at a frequency of 54.1 MHz, was located at Pirlangimpi (Garden Point) (11.4°S, 130.5°E) on the Tiwi Islands. Observations were made regularly up to heights near 8 km, with maximum heights occurring when convective activity was strongest. Mean winds observed between October and December 2001 are in good agreement with conditions that prevailed across northern Australia during this period. During the first two intensive observation periods (IOP) during October and November, the zonal and meridional wind components were westward and northward, respectively, with stronger values in November. By the time of IOP3 in mid-December, the zonal flow was eastward, a pattern that is typical of the Australian monsoon. Fluctuations in the three wind components for periods less than 3 hours are analyzed for IOP2 in November, when strong convective storms ("Hectors") occurred on all afternoons over the Tiwi Islands. The fluctuations, which are ascribed to convectively generated gravity waves, show a correspondingly strong diurnal cycle, with horizontal wind variances peaking between 8 and 12 m2s-2 in the early afternoon in the lower troposphere. Variances are only ˜2 m2s-2 in the early morning hours. A power spectral analysis shows that oscillations with ground-based periods between 8 and 17 min are especially prominent during Hector events. The profiler observations are compared with a numerical model study of gravity wave generation by convection on 17 November 2001. There is a satisfactory degree of agreement between the behavior of the model and profiler oscillations, both as a function of height and time.

  17. Calculating the azimuth of mountain waves, using the effect of tilted fine-scale stable layers on VHF radar echoes

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    Full Text Available A simple method is described, based on standard VHF wind-profiler data, where imbalances of echo power between four off-vertical radar beams, caused by mountain waves, can be used to calculate the orientation of the wave pattern. It is shown that the mountain wave azimuth (direction of the horizontal component of the wavevector, is given by the vector [ W (PE - P W ,W (PN - P S ]; PN, PS, PE, PW are radar echo powers, measured in dB, in beams pointed away from vertical by the same angle towards north, south, east and west respectively, and W is the vertical wind velocity. The method is applied to Aberystwyth MST radar data, and the calculated wave vector usually, but not always, points into the low-level wind direction. The mean vertical wind at Aberystwyth, which may also be affected by tilted aspect-sensitive layers, is investigated briefly using the entire radar output 1990-1997. The mean vertical-wind profile is inconsistent with existing theories, but a new mountain-wave interpretation is proposed.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides; instruments and techniques.

  18. VHF SoOp (Signal of Opportunity) Technology Demonstration for Soil Moisture Measurement Using Microwave Hydraulic Boom Truck Platform

    Science.gov (United States)

    Joseph, A. T.; Deshpande, M.; O'Neill, P. E.; Miles, L.

    2017-01-01

    A goal of this research is to test deployable VHF antennas for 6U Cubesat platforms to enable validation of root zone soil moisture (RZSM) estimation algorithms for signal of opportunity (SoOp) remote sensing over the 240-270 MHz frequency band. The proposed work provides a strong foundation for establishing a technology development path for maturing a global direct surface soil moisture (SM) and RZSM measurement system over a variety of land covers. Knowledge of RZSM up to a depth of 1 meter and surface SM up to a depth of 0.05 meter on a global scale, at a spatial resolution of 1-10 km through moderate-to-heavy vegetation, is critical to understanding global water resources and the vertical moisture gradient in the Earths surface layer which controls moisture interactions between the soil, vegetation, and atmosphere. Current observations of surface SM from space by L-band radiometers (1.4 GHz) and radars (1.26 GHz) are limited to measurements of surface SM up to a depth of 0.05 meter through moderate amounts of vegetation. This limitation is mainly due to the inability of L-band signals to penetrate through dense vegetation and deep into the soil column. Satellite observations of the surface moisture conditions are coupled to sophisticated models which extrapolate the surface SM into the root zone, thus providing an indirect estimate rather than a direct measurement of RZSM. To overcome this limitation, low-frequency airborne radars operating at 435 MHz and 118 MHz have been investigated, since these lower frequencies should penetrate denser vegetation and respond to conditions deeper in the soil.

  19. Morphological study of the field-aligned E-layer irregularities observed by the Gadanki VHF radar

    Directory of Open Access Journals (Sweden)

    C. J. Pan

    2004-11-01

    Full Text Available We report on the field-aligned irregularities observed in the low-latitude sporadic E-layer (Es with the Gadanki (13.5° N, 79.2° E; geomagnetic latitude 6.3° N VHF radar. The radar was operated intermittently for 15 days during the summer months in 1998 and 1999, for both daytime and nighttime observation. The total observation periods are 161h for the nighttime and 68h for the daytime. The observations were used to study the percentage of occurrence of the E-region echoes for both daytime and nighttime. The statistical characteristics of the mean radial velocity and spectral width are presented for three cases based on the echo occurrence characteristics and the altitude of observations (from 90 to 140km ranges, namely, the lower E-region daytime (90-110km, the lower E-region nighttime (90-105km and the upper E-region nighttime (105-140km echoes. The results are compared with that of Piura, a low-latitude station located at about the same geomagnetic latitude, but to the south of the equator. By comparing the behaviors of the lower E-region radar echoes of the summer months between Gadanki and Piura, we find that the lower altitude echoes below about 100km are rarely reported in Piura but commonly seen in Gadanki. Features of the nighttime echoes observed by these two radars are quite similar but daytime FAI echoes are again seldom detected by Piura.

  20. VHF radar observation of atmospheric winds, associated shears and C2n at a tropical location: interdependence and seasonal pattern

    Directory of Open Access Journals (Sweden)

    A. R. Jain

    Full Text Available The turbulence refractivity structure constant (C2n is an important parameter of the atmosphere. VHF radars have been used extensively for the measurements of C2n. Presently, most of such observations are from mid and high latitudes and only very limited observations are available for equatorial and tropical latitudes. Indian MST radar is an excellent tool for making high-resolution measurements of atmospheric winds, associated shears and turbulence refractivity structure constant (C2n. This radar is located at Gadanki (13.45° N, 79.18° E, a tropical station in India. The objective of this paper is to bring out the height structure of C2n for different seasons using the long series of data (September 1995 – August 1999 from Indian MST radar. An attempt is also made to understand such changes in the height structure of C2n in relation to background atmospheric parameters such as horizontal winds and associated shears. The height structure of C2n, during the summer monsoon and post-monsoon season, shows specific height features that are found to be related to Tropical Easterly Jet (TEJ winds. It is important to examine the nature of the radar back-scatterers and also to understand the causative mechanism of such scatterers. Aspect sensitivity of the received radar echo is examined for this purpose. It is observed that radar back-scatterers at the upper tropospheric and lower stratospheric heights are more anisotropic, with horizontal correlation length of 10–20 m, as compared to those observed at lower and middle tropospheric heights.Key words. Meteorology and atmospheric dynamics (climatology; tropical meteorology; turbulence

  1. Spatial variability of the aspect sensitivity of VHF radar echoes in the troposphere and lower stratosphere during jet stream passages

    Directory of Open Access Journals (Sweden)

    J. G. Yoe

    Full Text Available The aspect sensitivity of SOUSY-VHF-radar oblique-beam echoes from the troposphere and lower stratosphere has been examined for a number of jet stream passages during the years 1990 - 1992. When the core of the jet is overhead or nearly so, vertical profiles of the aspect sensitivity display two notable features. First, the distinction between mainly isotropic and strongly aspect-sensitive echoes in the troposphere and the lower stratosphere, respectively, often reported for measurements made during calm conditions, does not necessarily prevail in the vicinity of the jet stream. Second, echoes obtained at altitudes near the height of the horizontal wind maximum are found to be more aspect sensitive for beams directed parallel to the horizontal flow or nearly so, than for other beam directions. It is demonstrated that time-averaged horizontal wind speeds estimated from the radar data, taking into account the reduced effective oblique-beam zenith angle resulting from aspect sensitivity, may exceed uncorrected wind speeds by as much as 10 m s-1 in these circumstances. Implications for wind profiling and for describing the backscattering process are discussed. Doppler spectral widths examined for one jet stream passage are found to be narrower in a beam aligned with the horizontal wind at heights near the wind speed maximum than corresponding widths measured in a beam projected at right angles to the jet. The narrowest spectra thus coincide with the most aspect-sensitive echoes, consistent with the hypothesis that such returns result from specular backscattering processes.

  2. A no-tune no-match wideband probe for nuclear quadrupole resonance spectroscopy in the VHF range

    Science.gov (United States)

    Scharfetter, Hermann; Petrovic, Andreas; Eggenhofer, Heidi; Stollberger, Rudolf

    2014-12-01

    Nuclear quadrupole resonance (NQR) spectroscopy is a method for the characterization of chemical compounds containing so-called quadrupolar nuclei. Similar to nuclear magnetic resonance (NMR), the sample under investigation is irradiated with strong radiofrequency (RF) pulses, which stimulate the emission of weak RF signals from the quadrupolar nuclei. The signals are then amplified and Fourier transformed so as to obtain a spectrum. In principle, narrowband NQR spectra can be measured with NMR spectrometers. However, pure NQR signals require the absence of a static magnetic field and several special applications require the characterization of a substance over a large bandwidth, e.g. 50-100% of the central frequency, which is hardly possible with standard NMR equipment. Dedicated zero-field NQR equipment is not widespread and current concepts employ resonating probes which are tuned and matched over a wide range by using mechanical capacitors driven by stepper motors. While providing the highest signal to noise ratio (SNR) such probes are slow in operation and can only be operated from dedicated NMR consoles. We developed a low-cost NQR wideband probe without tuning and matching for applications in the very high frequency (VHF) range below 300 MHz. The probe coil was realized as part of a reactive network which approximates an exponential transmission line. The input reflection coefficient of the two developed prototype probe coils is ≤ 20 dB between 90-145 MHz and 74.5-99.5 MHz, respectively. Two wideband NQR spectra of published test substances were acquired with an SNR of better than 20 dB after sufficient averaging. The measured signals and the SNR correspond very well to the theoretically expected values and demonstrate the feasibility of the method. Because there is no need for tuning and matching, our probes can be operated easily from any available NMR console.

  3. High resolution VHF radar measurements of tropopause structure and variability at Davis, Antarctica (69° S, 78° E

    Directory of Open Access Journals (Sweden)

    S. P. Alexander

    2013-03-01

    Full Text Available Two years of Very High Frequency (VHF radar echo power observations are used to examine the structure and variability of the tropopause at Davis, Antarctica. Co-located radiosonde and ozonesonde launches provide data with which to calculate the lapse-rate and chemical tropopauses. The radar tropopause, defined as the maximum vertical gradient of echo return power, can be used as a definition of the Antarctic tropopause throughout the year under all meteorological conditions. During the extended summer period of December–April (DJFMA inclusive, radar tropopauses are (0.2 ± 0.4 km lower than radiosonde lapse-rate (i.e. the World Meteorological Organisation – WMO tropopauses and during the extended winter period of June–October (JJASO inclusive, the radar tropopauses are (0.8 ± 1.0 km lower. A potential vorticity tropopause is defined as the altitude of the −2 PVU surface (where 1 PVU = 106 m2 s−1 K kg−1. This is (0.3 ± 0.5 km lower than the radar tropopause during DJFMA and (0.5 ± 1.0 km lower during JJASO. The radar, potential vorticity and ozone tropopauses decrease in altitude during increasingly strong cyclonic conditions, in contrast to the radiosonde WMO tropopause which remains nearly constant. During strong JJASO cyclonic conditions, there are large (several km differences between WMO tropopause altitudes and radar tropopause altitudes. A seasonal cycle in tropopause fold occurrence is observed, with approximately a three-fold increase during JJASO.

  4. Evolution of E2 transition strength in deformed hafnium isotopes from new measurements on $^{172}$Hf, $^{174}$Hf, and $^{176}$Hf

    CERN Document Server

    Rudigier, M; Dannhoff, M; Gerst, R-B; Jolie, J; Saed-Samii, N; Stegemann, S; Régis, J-M; Robledo, L M; Rodríguez-Guzmán, R; Blazhev, A; Fransen, Ch; Warr, N; Zell, K O

    2015-01-01

    The available data for E2 transition strengths in the region between neutron-deficient Hf and Pt isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf. We remeasure the 2^+_1 half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. The half-lives were measured using \\gamma-\\gamma and conversion-electron-\\gamma delayed coincidences with the fast timing method. For the determination of half-lives i...

  5. Mobility Management of VHF Dynamic Access in Low-altitude Airspace%低空空域VHF动态接入移动性管理

    Institute of Scientific and Technical Information of China (English)

    严雯

    2014-01-01

    The mobility management of Very High Frequency(VHF) dynamic access in low-altitude air-space is the key to realize uninterrupted and cross regional communication for low attitude flight. According to the low-altitude airspace communication network architecture,a hierarchical mobility management model is designed by Home Location Register/Visitor Location Register ( HLR/VLR ) mechanism with the suc-cessful experiences of Global System for Mobile( GSM) ,which dresses the issue of aircrafts location man-agement effectively. Registration,logging in/out,inter and intra station mobility management are described in detail. Finally,the delay of mobility management is analyzed and simulation is demonstrated,which lays foundation for further research on mobility management of VHF dynamic access.%低空空域超短波( VHF)动态接入移动性管理技术是保障低空飞行不间断、跨区域通信的关键。根据低空空管通信网络框架,设计了低空空管二级移动性管理模型;借鉴GSM经典移动性管理模型,引入访问/归属位置寄存器机制,解决了地面通信网有效管理低空飞行器位置信息的问题。详细阐述了登记注册、入网/退网、站内移动性管理和站间移动性管理等流程。最后,分析了移动性管理时延,并给出了系统演示和仿真,为进一步研究打下了基础。

  6. Comparative study of atomic-layer-deposited HfO2/Al2O3, Hf0.8Al0.2Ox and Hf0.5Al0.5Ox on N-GaAs

    Science.gov (United States)

    Yu, Xinjiang; Lv, Hongliang; Zhang, Yuming; Zhang, Yimen; Qin, Zaiyang

    2016-11-01

    Interfacial properties of n-GaAs metal-oxide-semiconductor (MOSCAPs) with the gate dielectrics of HfO2/Al2O3, Hf0.8Al0.2Ox and Hf0.5Al0.5Ox are investigated. The results reveal that Hf0.5Al0.5Ox has larger permittivity and lower interface trap density than that of HfO2/Al2O3. In order to explain the result from the physical perspective, the XPS tests of all three samples are performed. It is found that the main reason to form interface trap of three samples treated with 500 °C post-deposition annealing, is attributed to the interfacial component of Ga2O3 and The Hf0.5Al0.5Ox dielectric is beneficial to reducing the formation of Ga2O3.

  7. A DFT Study of Multimode Switching in a Combined DHA/VHF-DTE/DHB System for Use in Solar Heat Batteries

    DEFF Research Database (Denmark)

    Gertsen, Anders Skovbo; Olsen, Stine Tetzschner; Broman, Søren Lindbæk

    2017-01-01

    /vinylheptafulvene (DHA/VHF) photo-/thermoswitch with the dithienylethene/dihydrothienobenzothiophene (DTE/DHB) photoswitch could potentially meet these challenges. The combined multimode switch is studied by density functional theory in order to predict its energy storage properties and spectral behavior in various...... solvents before discussing its suitability for use in solar heat batteries. An energy storage capacity of 0.17 MJ/kg is calculated which corresponds to a specific energy of 46 Wh/kg—slightly larger than that of a common lead–acid car battery (∼40 Wh/kg) but still only one-fourth of lithium-ion batteries...

  8. Application of the Strong Scatter Theory to the Interpretation of Ionospheric Scintillation Measurements along Geostationary Satellite Links at VHF and L-band

    Science.gov (United States)

    Carrano, C. S.; Groves, K. M.; Basu, S.; Mackenzie, E.; Sheehan, R. E.

    2013-12-01

    In a previous work, we demonstrated that ionospheric turbulence parameters may be inferred from amplitude scintillations well into in the strong scatter regime [Carrano et al., International Journal of Geophysics, 2012]. This technique, called Iterative Parameter Estimation (IPE), uses the strong scatter theory and numerical inversion to estimate the parameters of an ionospheric phase screen (turbulent intensity, phase spectral index, and irregularity zonal drift) consistent with the observed scintillations. The optimal screen parameters are determined such that the theoretical intensity spectrum on the ground best matches the measured intensity spectrum in a least squares sense. We use this technique to interpret scintillation measurements collected during a campaign at Ascension Island (7.96°S, 14.41°W) in March 2000, led by Santimay Basu and his collaborators from Air Force Research Laboratory. Geostationary satellites broadcasting radio signals at VHF and L-band were monitored along nearly co-linear links, enabling a multi-frequency analysis of scintillations with the same propagation geometry. The VHF data were acquired using antennas spaced in the magnetic east-west direction, which enabled direct measurement of the zonal irregularity drift. We show that IPE analysis of the VHF and L-Band scintillations, which exhibited very different statistics due to the wide frequency separation, yields similar estimates of the phase screen parameters that specify the disturbed ionospheric medium. This agreement provides confidence in our phase screen parameter estimates. It also suggests a technique for extrapolating scintillation measurements to frequencies other than those observed that is valid in the case of strong scatter. We find that IPE estimates of the zonal irregularity drift, made using scintillation observations along single space-to-ground link, are consistent with those measured independently using the spaced antenna technique. This encouraging result

  9. The multilayer Fe/Hf studied with slow positron beam

    Science.gov (United States)

    Murashige, Y.; Tashiro, M.; Nakajyo, T.; Koizumi, T.; Kanazawa, I.; Komori, F.; Ito, Y.

    1997-04-01

    The positron annihilation parameter versus the incident positron energy is measured in the thin Fe films and the Fe/Hf bilayer on silica substrate, by means of the variable energetic slow-positron beam technique. We have analyzed the change in open-volume spaces and vacancy-type defects among the Fe microcrystals in these thin films with the deposition temperature.

  10. A CMOS OTA for HF filters with programmable transfer function

    NARCIS (Netherlands)

    van de Zwan, Eric J.; Klumperink, Eric A.M.; Seevinck, E.; Seevinck, Evert

    1991-01-01

    A CMOS operational transconductance amplifier (OTA) for programmable HF filters is presented. When used in an OTA-C integrator, the unity-gain frequency phase error remains less than 0.3° for frequencies up to more than one tenth of the OTA bandwidth. The OTA has built-in phase compensation, which

  11. Hf isotope evidence for a hidden mantle reservoir

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.

    2002-01-01

    High-precision Hf isotopic analyses and U-Pb ages of carbonatites and kimberlites from Greenland and eastern North America, including Earth's oldest known carbonatite (3 Ga), indicate derivation from an enriched mantle source. This previously unidentified mantle reservoir-marked by an unradiogeni...

  12. Origin of excess 176Hf in meteorites

    DEFF Research Database (Denmark)

    Thrane, Kristine; Connelly, James; Bizzarro, Martin

    2010-01-01

    After considerable controversy regarding the (176)Lu decay constant (lambda(176)Lu), there is now widespread agreement that (1.867 +/- 0.008) x 10(-11) yr(-1) as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the (176)Hf excesses that are correlated with...

  13. Self-diffusion of Er and Hf inpure and HfO/sub 2/-doped polycrystalline Er/sub 2/O/sub 3/. [Hf-175 and Er-169

    Energy Technology Data Exchange (ETDEWEB)

    Scheidecker, R.W.

    1979-01-01

    Using a tracer technique, self-diffusion of Er and Hf was measured over the approximate temperature interval of 1600 to 1970/sup 0/C in pure and HfO/sub 2/-doped polycryatalline Er/sub 2/O/sub 3/. Up to about 10 m/o HfO/sub 2/ dopant level, the Er self-diffusion coefficients followed a relationship based on cation vacancies. Above 10 m/o HfO/sub 2/, deviation from this relationship occurred, apparently due to clustering of cation vacancies and oxygen interstitials around the dopant hafnia ion. The activation energy for the self-diffusion of Er in pure Er/sub 2/O/sub 3/ was 82.2 Kcal/mole and increased with the HfO/sub 2/ dopant level present. Self-diffusion of Hf was measured in pure Er/sub 2/O/sub 3/ having two impurity levels, and a separation of the grain boundary. The volume diffusion of Hf showed both extrinsic and intrinsic behavior with the transition temperature increasing with the impurity level present in Er/sub 2/O/sub 3/. The activation energy for Hf volume diffusion in the intrinsic region was high, i.e. 235 -+ 9.5 Kcal/mole. The grain boundary diffusion was apparently extrinsic over the entire temperature interval Very low Hf self diffusion rates were found in both pure and HfO/sub 2/ doped Er/sub 2/O/sub 3/ compositions. Despite a clustering effect, the HfO/sub 2/ dopant increased the Hf volume diffusion coefficients.

  14. 一种船舶自动识别系统甚高频信道的低成本设计%Low-cost Design of VHF Channel in Automatic Identification System

    Institute of Scientific and Technical Information of China (English)

    张翼周

    2014-01-01

    With increasing competition in Automatic Identification System( AIS) market, low-cost design is the inevitable trend in AIS product development. This paper presents a low-cost Very High Frequency (VHF) channel design scheme of AIS system according to the International Maritime Organization(IMO) standards. The working principle of AIS and working process of its VHF channel are introduced briefly, a concise and practical transmitter and receiver design is given. And the design method,components selec-tion of some core units,such as modulator,VHF power-amplifier and demodulator are elaborated. The test and field practice show that all indexes of the VHF channel meet the specified requirements,further more, the VHF channel has low hardware cost and has reliable performance.%随着船舶自动识别系统( AIS)市场竞争的日益激烈,低成本化是AIS产品研制的必然趋势。根据国际海事组织( IMO)有关标准,给出了一种AIS甚高频( VHF)信道的低成本设计方案。介绍了AIS工作原理及其VHF信道的工作过程,给出了简洁实用的发射机和接收机设计,并对调制器、VHF功放、解调器等核心单元设计方法、器件选择进行了详细阐述。测试和外场实用表明该VHF信道各项指标均已达到规定要求,并且该VHF信道硬件成本低,性能可靠。

  15. Helium implanted $\\rm\\underline{Al}$Hf as studied by 181Ta TDPAC

    Indian Academy of Sciences (India)

    R Govindaraj; K P Gopinathan; B Viswanathan

    2000-06-01

    Time differential perturbed angular correlation (TDPAC) measurement on $\\rm\\underline{Al}$Hf reference sample has shown that a fraction 0.88 of probe nuclei are defect free and are occupying the substitutional sites in fcc Al matrix, and the remaining are associated with Hf solute clusters. Measurements on helium implanted sample indicate the binding of helium associated defects by Hf solute clusters. Isochronal annealing measurements indicate the dissociation of the helium implantation induced defects from Hf solute clusters for annealing treatments beyond 650 K. On comparison of the present results with that reported in $\\rm\\underline{Cu}$Hf subjected to identical helium implantation, it is inferred that the Hf solute clusters in $\\rm\\underline{Al}$Hf bind less strongly the helium associated defects than in $\\rm\\underline{Cu}$Hf.

  16. Processing and crystallographic structure of non-equilibrium Si-doped HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dong; Fancher, Chris M.; Esteves, Giovanni; Jones, Jacob L., E-mail: jacobjones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Zhao, Lili [School of Information Science and Technology, Northwest University, Xi' an 710127 (China)

    2015-06-28

    Si-doped HfO{sub 2} was confirmed to exist as a non-equilibrium state. The crystallographic structures of Si-doped HfO{sub 2} were studied using high-resolution synchrotron X-ray diffraction and the Rietveld refinement method. Incorporation of Si into HfO{sub 2} and diffusion of Si out of (Hf,Si)O{sub 2} were determined as a function of calcination temperature. Higher thermal energy input at elevated calcination temperatures resulted in the formation of HfSiO{sub 4}, which is the expected major secondary phase in Si-doped HfO{sub 2}. The effect of SiO{sub 2} particle size (nano- and micron-sized) on the formation of Si-doped HfO{sub 2} was also determined. Nano-crystalline SiO{sub 2} was found to incorporate into HfO{sub 2} more readily.

  17. Data of evolutionary structure change: 1CLMA-2HF5A [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1CLMA-2HF5A 1CLM 2HF5 A A LTEEQIAEFKEAFALFDKDGDGTITTKELGTVMRSLGQN...PTEAELQDMINEVDADGNGTIDFPEFLSLMARKMKEQDSEEELIEAFKVFDRDGNGLISAAELRHVMTNLGEKL--TDDEVDEMIREADIDGDGHINYEEFVRMMVS-...ntryChain> 1CLM A 1CLMA LGEKL--TD...ne> 1CLM A 1CLMA

  18. Geographic variations in the PARADIGM-HF heart failure trial.

    Science.gov (United States)

    Kristensen, Søren Lund; Martinez, Felipe; Jhund, Pardeep S; Arango, Juan Luis; Bĕlohlávek, Jan; Boytsov, Sergey; Cabrera, Walter; Gomez, Efrain; Hagège, Albert A; Huang, Jun; Kiatchoosakun, Songsak; Kim, Kee-Sik; Mendoza, Iván; Senni, Michele; Squire, Iain B; Vinereanu, Dragos; Wong, Raymond Ching-Chiew; Gong, Jianjian; Lefkowitz, Martin P; Rizkala, Adel R; Rouleau, Jean L; Shi, Victor C; Solomon, Scott D; Swedberg, Karl; Zile, Michael R; Packer, Milton; McMurray, John J V

    2016-11-01

    The globalization of clinical trials has highlighted geographic variations in patient characteristics, event rates, and treatment effects. We investigated these further in PARADIGM-HF, the largest and most globally representative trial in heart failure (HF) to date. We looked at five regions: North America (NA) 602 (8%), Western Europe (WE) 1680 (20%), Central/Eastern Europe/Russia (CEER) 2762 (33%), Latin America (LA) 1433 (17%), and Asia-Pacific (AP) 1487 (18%). Notable differences included: WE patients (mean age 68 years) and NA (65 years) were older than AP (58 years) and LA (63 years) and had more coronary disease; NA and CEER patients had the worst signs, symptoms, and functional status. North American patients were the most likely to have a defibrillating-device (54 vs. 2% AP) and least likely prescribed a mineralocorticoid receptor antagonist (36 vs. 65% LA). Other evidence-based therapies were used most frequently in NA and WE. Rates of the primary composite outcome of cardiovascular (CV) death or HF hospitalization (per 100 patient-years) varied among regions: NA 13.6 (95% CI 11.7-15.7) WE 9.6 (8.6-10.6), CEER 12.3 (11.4-13.2), LA 11.2 (10.0-12.5), and AP 12.5 (11.3-13.8). After adjustment for prognostic variables, relative to NA, the risk of CV death was higher in LA and AP and the risk of HF hospitalization lower in WE. The benefit of sacubitril/valsartan was consistent across regions. There were many regional differences in PARADIGM-HF, including in age, symptoms, comorbidity, background therapy, and event-rates, although these did not modify the benefit of sacubitril/valsartan. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01035255. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

  19. Mid-Latitude Mobile Wideband HF- NVIS Channel Analysis: Part 1

    Science.gov (United States)

    2017-09-14

    communications (SATCOM) for beyond line-of- sight (LOS) links. However, standard HF systems operating over a 3-kHz bandwidth do not provide sufficient...wideband mid-latitude HF channel soundings and three-dimensional (3-D) ray-tracing simulations to develop a statistical model of a particular nearly...46 5 THE HF-NVIS CHANNEL SOUNDING SYSTEM ...................................................................... 47 5.1 TRANSMIT AND RECEIVE HF

  20. HF Radar observations of the Dardanelles outflow current in North Eastern Aegean using validated WERA HF radar data

    Directory of Open Access Journals (Sweden)

    Z. KOKKINI

    2015-01-01

    Full Text Available A two-site WERA HF radar station was installed in November 2009 at the eastern coast of Lemnos Island in North Aegean Sea, aiming to monitor the surface inflow of Black Sea waters exiting from the Dardanelles Strait, as well as to constitute a coastal management tool for incidents of oil-pollution or save-and-rescue operations. Strong interference by foreign transmissions is a source of noise deteriorating the quality of the backscattered signal, thus significantly reducing the HF radar’s effective data return rate. In order to ameliorate this problem, further quality-control and data gap interpolating procedures have been developed and applied, to be used in addition to the procedures incorporated and used by the manufacturer’s signal processing software. The second-level processing involves traditional despiking in the temporal domain, preceding Empirical Orthogonal Function analysis. The latter is used not only to filter high-frequency noise but also to fill data gaps in time and space. The data reconstruction procedure has been assessed via comparison of (a HF radial with CODE-type drifter radial velocities as well as (b HF-derived virtual drifter tracks with actual drifter tracks. The main circulation features and their variability, as revealed by the reconstructed fields, are presented.