WorldWideScience

Sample records for s-band radar s-pol

  1. Mapping Forest Cover and Forest Cover Change with Airborne S-Band Radar

    Directory of Open Access Journals (Sweden)

    Ramesh K. Ningthoujam

    2016-07-01

    Full Text Available Assessments of forest cover, forest carbon stocks and carbon emissions from deforestation and degradation are increasingly important components of sustainable resource management, for combating biodiversity loss and in climate mitigation policies. Satellite remote sensing provides the only means for mapping global forest cover regularly. However, forest classification with optical data is limited by its insensitivity to three-dimensional canopy structure and cloud cover obscuring many forest regions. Synthetic Aperture Radar (SAR sensors are increasingly being used to mitigate these problems, mainly in the L-, C- and X-band domains of the electromagnetic spectrum. S-band has not been systematically studied for this purpose. In anticipation of the British built NovaSAR-S satellite mission, this study evaluates the benefits of polarimetric S-band SAR for forest characterisation. The Michigan Microwave Canopy Scattering (MIMICS-I radiative transfer model is utilised to understand the scattering mechanisms in forest canopies at S-band. The MIMICS-I model reveals strong S-band backscatter sensitivity to the forest canopy in comparison to soil characteristics across all polarisations and incidence angles. Airborne S-band SAR imagery over the temperate mixed forest of Savernake Forest in southern England is analysed for its information content. Based on the modelling results, S-band HH- and VV-polarisation radar backscatter and the Radar Forest Degradation Index (RFDI are used in a forest/non-forest Maximum Likelihood classification at a spatial resolution of 6 m (70% overall accuracy, κ = 0.41 and 20 m (63% overall accuracy, κ = 0.27. The conclusion is that S-band SAR such as from NovaSAR-S is likely to be suitable for monitoring forest cover and its changes.

  2. A multi-channel S-band FMCW radar front-end

    NARCIS (Netherlands)

    Maas, A.P.M.; Vliet, F.E. van

    2008-01-01

    This paper describes the design and performance of a low-cost synthesized FMCW radar module, operating in S band. The bi-layer PCB contains a frequency-agile low phase-noise synthesizer and three identical coherent receive-channels. The transmit channel has an automatic power control system that

  3. GPM GROUND VALIDATION NASA S-BAND DUAL POLARIMETRIC (NPOL) DOPPLER RADAR IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar IFloodS data set was collected from April 30, 2013 to June 16, 2013 near Traer, Iowa as...

  4. Intercomparison of attenuation correction algorithms for single-polarized X-band radars

    Science.gov (United States)

    Lengfeld, K.; Berenguer, M.; Sempere Torres, D.

    2018-03-01

    Attenuation due to liquid water is one of the largest uncertainties in radar observations. The effects of attenuation are generally inversely proportional to the wavelength, i.e. observations from X-band radars are more affected by attenuation than those from C- or S-band systems. On the other hand, X-band radars can measure precipitation fields in higher temporal and spatial resolution and are more mobile and easier to install due to smaller antennas. A first algorithm for attenuation correction in single-polarized systems was proposed by Hitschfeld and Bordan (1954) (HB), but it gets unstable in case of small errors (e.g. in the radar calibration) and strong attenuation. Therefore, methods have been developed that restrict attenuation correction to keep the algorithm stable, using e.g. surface echoes (for space-borne radars) and mountain returns (for ground radars) as a final value (FV), or adjustment of the radar constant (C) or the coefficient α. In the absence of mountain returns, measurements from C- or S-band radars can be used to constrain the correction. All these methods are based on the statistical relation between reflectivity and specific attenuation. Another way to correct for attenuation in X-band radar observations is to use additional information from less attenuated radar systems, e.g. the ratio between X-band and C- or S-band radar measurements. Lengfeld et al. (2016) proposed such a method based isotonic regression of the ratio between X- and C-band radar observations along the radar beam. This study presents a comparison of the original HB algorithm and three algorithms based on the statistical relation between reflectivity and specific attenuation as well as two methods implementing additional information of C-band radar measurements. Their performance in two precipitation events (one mainly convective and the other one stratiform) shows that a restriction of the HB is necessary to avoid instabilities. A comparison with vertically pointing

  5. Aercibo S-band radar program

    International Nuclear Information System (INIS)

    Campbell, D.B.

    1988-01-01

    The high powered 12.6 cm wavelength radar on the 1000-ft Arecibo reflector is utilized for a number of solar system studies. Chief among these are: (1) surface reflectivity mapping of Venus, Mercury and the Moon. Resolutions achievable on Venus are less than 1.5 km over some areas, for Mercury about 30 km and for the Moon 200 m at present, (2) high time resolution ranging measurements to the surfaces of the terrestrial planets. These measurements are used to obtain profiles and scattering parameters in the equatorial region. They can also be used to test relativistic and gravitational theories by monitoring the rate of advance of the perihelion of the orbit of Mercury and placing limits on the stability of the gravitational constant, (3) measurements of the orbital parameters, figure, spin vector and surface properties of asteroids and comets, and (4) observations of the Galilean Satellites of Jupiter and the satellites of Mars, Phobos and Deimos. The Galilean Satellites of Jupiter were re-observed with the 12.6 cm radar for the first time since 1981. Much more accurate measurements of the scattering properties of the three icy satellites were obtained that generally confirmed previous observations. Unambiguous measurements of the cross section and circular polarizations ratio of Io were also obtained for the first time. The radar scattering properties of four mainbelt asteroids and one near-earth asteroid were studied

  6. Mini-RF S- and X-band Bistatic Observations of the Floor of Cabeus Crater

    Science.gov (United States)

    Patterson, Gerald Wesley; Stickle, Angela; Turner, Franklin; Jensen, James; Cahill, Joshua; Mini-RF Team

    2017-10-01

    The Mini-RF instrument aboard NASA’s Lunar Reconnaissance Orbiter (LRO) is a hybrid dual-polarized synthetic aperture radar (SAR) and operates in concert with the Arecibo Observatory (AO) and the Goldstone deep space communications complex 34 meter antenna DSS-13 to collect S- and X-band bistatic radar data of the Moon. Bistatic radar data provide a means to probe the near subsurface for the presence of water ice, which exhibits a strong response in the form of a Coherent Backscatter Opposition Effect (CBOE). This effect has been observed in radar data for the icy surfaces of the Galilean satellites, the polar caps of Mars, polar craters on Mercury, and terrestrial ice sheets in Greenland. Previous work using Mini-RF S-band (12.6 cm) bistatic data suggests the presence of a CBOE associated with the floor of the lunar south polar crater Cabeus. The LRO spacecraft has begun its third extended mission. For this phase of operations Mini-RF is leveraging the existing AO architecture to make S-band radar observations of additional polar craters (e.g., Haworth, Shoemaker, Faustini). The purpose of acquiring these data is to determine whether other polar craters exhibit the response observed for Cabeus. Mini-RF has also initiated a new mode of operation that utilizes the X-band (4.2cm) capability of the instrument receiver and a recently commissioned X/C-band transmitter within the Deep Space Network’s (DSN) Goldstone complex to collect bistatic X-band data of the Moon. The purpose of acquiring these data is to constrain the depth/thickness of materials that exhibit a CBOE response - with an emphasis on observing the floor of Cabeus. Recent Mini-RF X-band observations of the floors of the craters Cabeus do not show evidence for a CBOE. This would suggest that the upper ~0.5 meters of the regolith for the floor of Cabeus do not harber water ice in a form detectable at 4.2 cm wavelengths.

  7. Miniaturized Ka-Band Dual-Channel Radar

    Science.gov (United States)

    Hoffman, James P.; Moussessian, Alina; Jenabi, Masud; Custodero, Brian

    2011-01-01

    Smaller (volume, mass, power) electronics for a Ka-band (36 GHz) radar interferometer were required. To reduce size and achieve better control over RFphase versus temperature, fully hybrid electronics were developed for the RF portion of the radar s two-channel receiver and single-channel transmitter. In this context, fully hybrid means that every active RF device was an open die, and all passives were directly attached to the subcarrier. Attachments were made using wire and ribbon bonding. In this way, every component, even small passives, was selected for the fabrication of the two radar receivers, and the devices were mounted relative to each other in order to make complementary components isothermal and to isolate other components from potential temperature gradients. This is critical for developing receivers that can track each other s phase over temperature, which is a key mission driver for obtaining ocean surface height. Fully hybrid, Ka-band (36 GHz) radar transmitter and dual-channel receiver were developed for spaceborne radar interferometry. The fully hybrid fabrication enables control over every aspect of the component selection, placement, and connection. Since the two receiver channels must track each other to better than 100 millidegrees of RF phase over several minutes, the hardware in the two receivers must be "identical," routed the same (same line lengths), and as isothermal as possible. This level of design freedom is not possible with packaged components, which include many internal passive, unknown internal connection lengths/types, and often a single orientation of inputs and outputs.

  8. Perancangan Low Noise Amplifier dengan Teknik Non Simultaneous Conjugate Match untuk Aplikasi Radar S-Band

    Directory of Open Access Journals (Sweden)

    Yana Taryana

    2016-06-01

    Full Text Available Radar merupakan sistem pemancar dan penerima gelombang elektromagnetik untuk mendeteksi, mengukur jarak dan membuat peta benda benda seperti pesawat terbang, kapal laut, kendaran bermotor dan informasi cuaca. Salah satu kendala yang dihadapi pada sistem radar adalah sinyal pantulan yang memiliki daya yang rendah sehingga kualitas penerimaan menjadi kurang baik. Untuk mengatasi kendala tersebut dibutuhkan penguat daya pada sistem penerima yaitu Low Noise Amplifier (LNA. Oleh karena itu, tulisan ini memaparkan perancangan LNA dengan menggunakan teknik Non Simultaneous Conjugate Match (NSCM untuk aplikasi radar S-Band. Teknik ini memberikan kemudahan dalam menentukan nilai trade off (TO untuk nilai gain, noise figure (NF dan Voltage Standing Wave Ratio (VSWR yang diinginkan. Dalam proses perancangannya, perangkat lunak Agilent Design System (ADS 2011 digunakan untuk mendapatkan hubungan antara lingkaran gain, lingkaran NF, lingkaran VSWR, dan lingkaran mismatch factor (M. Dari hubungan tersebut diperoleh nilai impedansi masukan dan keluaran dari komponen aktif. Dalam tulisan ini, LNA dirancang dua tingkat untuk mendapatkan penguatan yang tinggi. Masing-masing tingkat menggunakan komponen aktif BJT BFP420 dengan penguatan dirancang sebesar 13,50 dB untuk tingkat pertama dan kedua, dan M sebesar 0,98. Sedangkan untuk saluran penyesuai impedansinya menggunakan substrat teflon fiberglass DiClad527. Hasil simulasi menunjukkan karakteristik LNA pada frekuensi 3 GHz yaitu gain sebesar 28,80 dB, NF sebesar 2,80 dB, VSWRin sebesar 1,05 dan VSWRout sebesar 1,1.

  9. Ranger© - An Affordable, Advanced, Next-Generation, Dual-Pol, X-Band Weather Radar

    Science.gov (United States)

    Stedronsky, Richard

    2014-05-01

    The Enterprise Electronics Corporation (EEC) Ranger© system is a new generation, X-band (3 cm), Adaptive Polarization Doppler Weather Surveillance Radar that fills the gap between high-cost, high-power traditional radar systems and the passive ground station weather sensors. Developed in partnership with the University of Oklahoma Advanced Radar Research Center (ARRC), the system uses relatively low power solid-state transmitters and pulse compression technology to attain nearly the same performance capabilities of much more expensive traditional radar systems. The Ranger© also employs Adaptive Dual Polarization (ADP) techniques to allow Alternating or Simultaneous Dual Polarization capability with total control over the transmission polarization state using dual independent coherent transmitters. Ranger© has been designed using the very latest technology available in the industry and the technical and manufacturing experience gained through over four decades of successful radar system design and production at EEC. The entire Ranger© design concept emphasizes precision, stability, reliability, and value using proven solid state technology combined with the most advanced motion control system ever conceived for weather radar. Key applications include meteorology, hydrology, aviation, offshore oil/gas drilling, wind energy, and outdoor event situational awareness.

  10. IoSiS: a radar system for imaging of satellites in space

    Science.gov (United States)

    Jirousek, M.; Anger, S.; Dill, S.; Schreiber, E.; Peichl, M.

    2017-05-01

    Space debris nowadays is one of the main threats for satellite systems especially in low earth orbit (LEO). More than 700,000 debris objects with potential to destroy or damage a satellite are estimated. The effects of an impact often are not identifiable directly from ground. High-resolution radar images are helpful in analyzing a possible damage. Therefor DLR is currently developing a radar system called IoSiS (Imaging of Satellites in Space), being based on an existing steering antenna structure and our multi-purpose high-performance radar system GigaRad for experimental investigations. GigaRad is a multi-channel system operating at X band and using a bandwidth of up to 4.4 GHz in the IoSiS configuration, providing fully separated transmit (TX) and receive (RX) channels, and separated antennas. For the observation of small satellites or space debris a highpower traveling-wave-tube amplifier (TWTA) is mounted close to the TX antenna feed. For the experimental phase IoSiS uses a 9 m TX and a 1 m RX antenna mounted on a common steerable positioner. High-resolution radar images are obtained by using Inverse Synthetic Aperture Radar (ISAR) techniques. The guided tracking of known objects during overpass allows here wide azimuth observation angles. Thus high azimuth resolution comparable to the range resolution can be achieved. This paper outlines technical main characteristics of the IoSiS radar system including the basic setup of the antenna, the radar instrument with the RF error correction, and the measurement strategy. Also a short description about a simulation tool for the whole instrument and expected images is shown.

  11. Performance of high-resolution X-band radar for rainfall measurement in The Netherlands

    Directory of Open Access Journals (Sweden)

    C. Z. van de Beek

    2010-02-01

    Full Text Available This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The aim of this paper is to present a thorough analysis of a climatological dataset using a high spatial (120 m and temporal (16 s resolution X-band radar. This makes it a study of the potential for high-resolution rainfall measurements with non-polarimetric X-band radar over flat terrain. An appropriate radar reflectivity – rain rate relation is derived from measurements of raindrop size distributions and compared with radar – rain gauge data. The radar calibration is assessed using a long-term comparison of rain gauge measurements with corresponding radar reflectivities as well as by analyzing the evolution of the stability of ground clutter areas over time. Three different methods for ground clutter correction as well as the effectiveness of forward and backward attenuation correction algorithms have been studied. Five individual rainfall events are discussed in detail to illustrate the strengths and weaknesses of high-resolution X-band radar and the effectiveness of the presented correction methods. X-band radar is found to be able to measure the space-time variation of rainfall at high resolution, far greater than what can be achieved by rain gauge networks or a typical operational C-band weather radar. On the other hand, SOLIDAR can suffer from receiver saturation, wet radome attenuation as well as signal loss along the path. During very strong convective situations the signal can even be lost completely. In combination with several rain gauges for quality control, high resolution X-band radar is considered to be suitable for rainfall monitoring over relatively small (urban catchments. These results offer great prospects for the new high resolution polarimetric doppler X-band radar IDRA.

  12. Preliminary Analysis of X-Band and Ka-Band Radar for Use in the Detection of Icing Conditions Aloft

    Science.gov (United States)

    Reehorst, Andrew L.; Koenig, George G.

    2004-01-01

    NASA and the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) have an on-going activity to develop remote sensing technologies for the detection and measurement of icing conditions aloft. Radar has been identified as a strong tool for this work. However, since the remote detection of icing conditions with the intent to identify areas of icing hazard is a new and evolving capability, there are no set requirements for radar sensitivity. This work is an initial attempt to quantify, through analysis, the sensitivity requirements for an icing remote sensing radar. The primary radar of interest for cloud measurements is Ka-band, however, since NASA is currently using an X-band unit, this frequency is also examined. Several aspects of radar signal analysis were examined. Cloud reflectivity was calculated for several forms of cloud using two different techniques. The Air Force Geophysical Laboratory (AFGL) cloud models, with different drop spectra represented by a modified gamma distribution, were utilized to examine several categories of cloud formation. Also a fundamental methods approach was used to allow manipulation of the cloud droplet size spectra. And an analytical icing radar simulator was developed to examine the complete radar system response to a configurable multi-layer cloud environment. Also discussed is the NASA vertical pointing X-band radar. The radar and its data system are described, and several summer weather events are reviewed.

  13. A comparative cepstral based analysis of simulated and measured S-band and X-band radar Doppler spectra of human motion

    CSIR Research Space (South Africa)

    Van Eeden, WD

    2015-10-01

    Full Text Available targets. It is also shown that, whereas the motion of most body parts of a human target can be observed in the X-band data, only the main torso sway can be observed at S-band. This implies that X-band data is well suited to cepstrum based human motion...

  14. Modeling L-band synthetic aperture radar observations through dielectric changes in soil moisture and vegetation over shrublands

    Science.gov (United States)

    L-band airborne synthetic aperture radar observations were made over California shrublands to better understand the effects by soil and vegetation parameters on backscatter. Temporal changes in radar backscattering coefficient (s0) of up to 3 dB were highly correlated to surface soil moisture but no...

  15. Flood Monitoring using X-band Dual-polarization Radar Network

    Science.gov (United States)

    Chandrasekar, V.; Wang, Y.; Maki, M.; Nakane, K.

    2009-09-01

    sensitivity and fast temporal update across the coverage. Strong clutter is expected from buildings in the neighborhood which act as perfect reflectors. The reduction in radar size enables flexible deployment, such as rooftop installation, with small infrastructure requirement, which is critical in a metropolitan region. Dual-polarization based technologies can be implemented for real-time mitigation of rain attenuations and accurate estimation of rainfall. The NSF Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is developing the technologies and the systems for network centric weather observation. The Differential propagation phase (Kdp) has higher sensitivity at X-band compared to S and C band. It is attractive to use Kdp to derive Quantitative Precipitation Estimation (QPE) because it is immune to rain attenuation, calibration biases, partial beam blockage, and hail contamination. Despite the advantage of Kdp for radar QPE, the estimation of Kdp itself is a challenge as the range derivative of the differential propagation phase profiles. An adaptive Kdp algorithm was implemented in the CASA IP1 testbed that substantially reduces the fluctuation in light rain and the bias at heavy rain. The Kdp estimation also benefits from the higher resolution in the IP1 radar network. The performance of the IP1 QPE product was evaluated for all major rain events against the USDA Agriculture Research Service's gauge network (MicroNet) in the Little Washita watershed, which comprises 20 weather stations in the center of the test bed. The cross-comparison with gauge measurements shows excellent agreement for the storm events during the Spring Experiments of 2007 and 2008. The hourly rainfall estimates compared to the gauge measurements have a very small bias of few percent and a normalized standard error of 21%. The IP1 testbed was designed with overlapping coverage among its radar nodes. The study area is covered by multiple radars and the aspect of

  16. An Algorithm for Surface Current Retrieval from X-band Marine Radar Images

    Directory of Open Access Journals (Sweden)

    Chengxi Shen

    2015-06-01

    Full Text Available In this paper, a novel current inversion algorithm from X-band marine radar images is proposed. The routine, for which deep water is assumed, begins with 3-D FFT of the radar image sequence, followed by the extraction of the dispersion shell from the 3-D image spectrum. Next, the dispersion shell is converted to a polar current shell (PCS using a polar coordinate transformation. After removing outliers along each radial direction of the PCS, a robust sinusoidal curve fitting is applied to the data points along each circumferential direction of the PCS. The angle corresponding to the maximum of the estimated sinusoid function is determined to be the current direction, and the amplitude of this sinusoidal function is the current speed. For validation, the algorithm is tested against both simulated radar images and field data collected by a vertically-polarized X-band system and ground-truthed with measurements from an acoustic Doppler current profiler (ADCP. From the field data, it is observed that when the current speed is less than 0.5 m/s, the root mean square differences between the radar-derived and the ADCP-measured current speed and direction are 7.3 cm/s and 32.7°, respectively. The results indicate that the proposed procedure, unlike most existing current inversion schemes, is not susceptible to high current speeds and circumvents the need to consider aliasing. Meanwhile, the relatively low computational cost makes it an excellent choice in practical marine applications.

  17. Evaluating the Solar Slowly Varying Component at C-Band Using Dual- and Single-Polarization Weather Radars in Europe

    Directory of Open Access Journals (Sweden)

    M. Gabella

    2017-01-01

    Full Text Available Six C-band weather radars located in Europe (Finland, Netherlands, and Switzerland have been used to monitor the slowly varying solar emission, which is an oscillation with an amplitude of several decibels and a period of approximately 27 days. It is caused by the fact that the number of active regions that enhance the solar radio emission with respect to the quiet component, as seen from Earth, varies because of the Sun’s rotation about its axis. The analysis is based on solar signals contained in the polar volume data produced during the operational weather scan strategy. This paper presents hundreds of daily comparisons between radar estimates and the Sun’s reference signal, during the current active Sun period (year 2014. The Sun’s reference values are accurately measured by the Dominion Radio Astrophysical Observatory (DRAO at S-band and converted to C-band using a standard DRAO formula. Vertical and horizontal polarization receivers are able to capture the monthly oscillation of the solar microwave signal: the standard deviation of the log-transformed ratio between radars and the DRAO reference ranges from 0.26 to 0.4 dB. A larger coefficient (and a different value for the quiet Sun component in the standard formula improves the agreement.

  18. Ambiguity Function and Resolution Characteristic Analysis of DVB-S Signal for Passive Radar

    Directory of Open Access Journals (Sweden)

    Jin Wei

    2012-12-01

    Full Text Available This paper gives the performance research on the ambiguity function and resolution of passive radar based on DVB-S (Digital Video Broadcasting-Satellite signal. The radar system structure and signal model of DVB-S signal are firstly studied, then the ambiguity function of DVB-S signal is analyzed. At last, it has been obtained how the bistatic radar position impacts the resolution. Theoretical analyses and computer simulation show that DVB-S signal is applicable as an illuminator for passive radar.

  19. Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

    Science.gov (United States)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

    2013-01-01

    A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

  20. A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band

    Science.gov (United States)

    Kelly, Kenneth C.; Huang, John

    2000-01-01

    A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L- Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.

  1. Airborne S-Band SAR for Forest Biophysical Retrieval in Temperate Mixed Forests of the UK

    Directory of Open Access Journals (Sweden)

    Ramesh K. Ningthoujam

    2016-07-01

    Full Text Available Radar backscatter from forest canopies is related to forest cover, canopy structure and aboveground biomass (AGB. The S-band frequency (3.1–3.3 GHz lies between the longer L-band (1–2 GHz and the shorter C-band (5–6 GHz and has been insufficiently studied for forest applications due to limited data availability. In anticipation of the British built NovaSAR-S satellite mission, this study evaluates the benefits of polarimetric S-band SAR for forest biophysical properties. To understand the scattering mechanisms in forest canopies at S-band the Michigan Microwave Canopy Scattering (MIMICS-I radiative transfer model was used. S-band backscatter was found to have high sensitivity to the forest canopy characteristics across all polarisations and incidence angles. This sensitivity originates from ground/trunk interaction as the dominant scattering mechanism related to broadleaved species for co-polarised mode and specific incidence angles. The study was carried out in the temperate mixed forest at Savernake Forest and Wytham Woods in southern England, where airborne S-band SAR imagery and field data are available from the recent AirSAR campaign. Field data from the test sites revealed wide ranges of forest parameters, including average canopy height (6–23 m, diameter at breast-height (7–42 cm, basal area (0.2–56 m2/ha, stem density (20–350 trees/ha and woody biomass density (31–520 t/ha. S-band backscatter-biomass relationships suggest increasing backscatter sensitivity to forest AGB with least error between 90.63 and 99.39 t/ha and coefficient of determination (r2 between 0.42 and 0.47 for the co-polarised channel at 0.25 ha resolution. The conclusion is that S-band SAR data such as from NovaSAR-S is suitable for monitoring forest aboveground biomass less than 100 t/ha at 25 m resolution in low to medium incidence angle range.

  2. Marine X-band Weather Radar Data Calibration

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2012-01-01

    estimates. This paper presents some of the challenges in small marine X-band radar calibration by comparing three calibration procedures for assessing the relationship between radar and rain gauge data. Validation shows similar results for precipitation volumes but more diverse results on peak rain......Application of weather radar data in urban hydrology is evolving and radar data is now applied for both modelling, analysis, and real time control purposes. In these contexts, it is allimportant that the radar data is well calibrated and adjusted in order to obtain valid quantitative precipitation...

  3. S-Band AlGaN/GaN power amplifier MMIC with over 20 Watt output power

    NARCIS (Netherlands)

    van Heijningen, M; Visser, G.C.; Wurfl, J.; van Vliet, Frank Edward

    2008-01-01

    Abstract This paper presents the design of an S-band HPA MMIC in AlGaN/GaN CPW technology for radar TR-module application. The trade-offs of using an MMIC solution versus discrete power devices are discussed. The MMIC shows a maximum output power of 38 Watt at 37% Power Added Efficiency at 3.1 GHz.

  4. S-Band AlGaN/GaN Power Amplifier MMIC with over 20 Watt Output Power

    NARCIS (Netherlands)

    Heijningen, M. van; Visser, G.C.; Wuerfl, J.; Vliet, F.E. van

    2008-01-01

    This paper presents the design of an S-band HPA MMIC in AlGaN/GaN CPW technology for radar TR-module application. The trade-offs of using an MMIC solution versus discrete power devices are discussed. The MMIC shows a maximum output power of 38 Watt at 37% Power Added Efficiency at 3.1 GHz. An output

  5. Typhoon 9707 observations with the MU radar and L-band boundary layer radar

    Directory of Open Access Journals (Sweden)

    M. Teshiba

    2001-08-01

    Full Text Available Typhoon 9707 (Opal was observed with the VHF-band Middle and Upper atmosphere (MU radar, an L-band boundary layer radar (BLR, and a vertical-pointing C-band meteorological radar at the Shigaraki MU Observatory in Shiga prefecture, Japan on 20 June 1997. The typhoon center passed about 80 km southeast from the radar site. Mesoscale precipitating clouds developed due to warm-moist airmass transport from the typhoon, and passed over the MU radar site with easterly or southeasterly winds. We primarily present the wind behaviour including the vertical component which a conventional meteorological Doppler radar cannot directly observe, and discuss the relationship between the wind behaviour of the typhoon and the precipitating system. To investigate the dynamic structure of the typhoon, the observed wind was divided into radial and tangential wind components under the assumption that the typhoon had an axi-symmetric structure. Altitude range of outflow ascended from 1–3 km to 2–10 km with increasing distance (within 80–260 km range from the typhoon center, and in-flow was observed above and below the outflow. Outflow and inflow were associated with updraft and downdraft, respectively. In the tangential wind, the maximum speed of counterclockwise winds was confirmed at 1–2 km altitudes. Based on the vertical velocity and the reflectivity obtained with the MU radar and the C-band meteorological radar, respectively, precipitating clouds, accompanied by the wind behaviour of the typhoon, were classified into stratiform and convective precipitating clouds. In the stratiform precipitating clouds, a vertical shear of radial wind and the maximum speed of counterclockwise wind were observed. There was a strong reflectivity layer called a ‘bright band’ around the 4.2 km altitude. We confirmed strong updrafts and down-drafts below and above it, respectively, and the existence of a relatively dry layer around the bright band level from radiosonde

  6. Typhoon 9707 observations with the MU radar and L-band boundary layer radar

    Directory of Open Access Journals (Sweden)

    M. Teshiba

    Full Text Available Typhoon 9707 (Opal was observed with the VHF-band Middle and Upper atmosphere (MU radar, an L-band boundary layer radar (BLR, and a vertical-pointing C-band meteorological radar at the Shigaraki MU Observatory in Shiga prefecture, Japan on 20 June 1997. The typhoon center passed about 80 km southeast from the radar site. Mesoscale precipitating clouds developed due to warm-moist airmass transport from the typhoon, and passed over the MU radar site with easterly or southeasterly winds. We primarily present the wind behaviour including the vertical component which a conventional meteorological Doppler radar cannot directly observe, and discuss the relationship between the wind behaviour of the typhoon and the precipitating system. To investigate the dynamic structure of the typhoon, the observed wind was divided into radial and tangential wind components under the assumption that the typhoon had an axi-symmetric structure. Altitude range of outflow ascended from 1–3 km to 2–10 km with increasing distance (within 80–260 km range from the typhoon center, and in-flow was observed above and below the outflow. Outflow and inflow were associated with updraft and downdraft, respectively. In the tangential wind, the maximum speed of counterclockwise winds was confirmed at 1–2 km altitudes. Based on the vertical velocity and the reflectivity obtained with the MU radar and the C-band meteorological radar, respectively, precipitating clouds, accompanied by the wind behaviour of the typhoon, were classified into stratiform and convective precipitating clouds. In the stratiform precipitating clouds, a vertical shear of radial wind and the maximum speed of counterclockwise wind were observed. There was a strong reflectivity layer called a ‘bright band’ around the 4.2 km altitude. We confirmed strong updrafts and down-drafts below and above it, respectively, and the existence of a relatively dry layer around the bright band level from radiosonde

  7. Classification and correction of the radar bright band with polarimetric radar

    Science.gov (United States)

    Hall, Will; Rico-Ramirez, Miguel; Kramer, Stefan

    2015-04-01

    The annular region of enhanced radar reflectivity, known as the Bright Band (BB), occurs when the radar beam intersects a layer of melting hydrometeors. Radar reflectivity is related to rainfall through a power law equation and so this enhanced region can lead to overestimations of rainfall by a factor of up to 5, so it is important to correct for this. The BB region can be identified by using several techniques including hydrometeor classification and freezing level forecasts from mesoscale meteorological models. Advances in dual-polarisation radar measurements and continued research in the field has led to increased accuracy in the ability to identify the melting snow region. A method proposed by Kitchen et al (1994), a form of which is currently used operationally in the UK, utilises idealised Vertical Profiles of Reflectivity (VPR) to correct for the BB enhancement. A simpler and more computationally efficient method involves the formation of an average VPR from multiple elevations for correction that can still cause a significant decrease in error (Vignal 2000). The purpose of this research is to evaluate a method that relies only on analysis of measurements from an operational C-band polarimetric radar without the need for computationally expensive models. Initial results show that LDR is a strong classifier of melting snow with a high Critical Success Index of 97% when compared to the other variables. An algorithm based on idealised VPRs resulted in the largest decrease in error when BB corrected scans are compared to rain gauges and to lower level scans with a reduction in RMSE of 61% for rain-rate measurements. References Kitchen, M., R. Brown, and A. G. Davies, 1994: Real-time correction of weather radar data for the effects of bright band, range and orographic growth in widespread precipitation. Q.J.R. Meteorol. Soc., 120, 1231-1254. Vignal, B. et al, 2000: Three methods to determine profiles of reflectivity from volumetric radar data to correct

  8. A New Ka-Band Scanning Radar Facility: Polarimetric and Doppler Spectra Measurements of Snow Events

    Science.gov (United States)

    Oue, M.; Kollias, P.; Luke, E. P.; Mead, J.

    2017-12-01

    Polarimetric radar analyses offer the capability of identification of ice hydrometeor species as well as their spatial distributions. In addition to polarimetric parameter observations, Doppler spectra measurements offer unique insights into ice particle properties according to particle fall velocities. In particular, millimeter-wavelength radar Doppler spectra can reveal supercooled liquid cloud droplets embedded in ice precipitation clouds. A Ka-band scanning polarimetric radar, named KASPR, was installed in an observation facility at Stony Brook University, located 22 km west of the KOKX NEXRAD radar at Upton, NY. The KASPR can measure Doppler spectra and full polarimetric variables, including radar reflectivity, differential reflectivity (ZDR), differential phase (φDP), specific differential phase (KDP), correlation coefficient (ρhv), and linear depolarization ratio (LDR). The facility also includes a micro-rain radar and a microwave radiometer capable of measuring reflectivity profiles and integrated liquid water path, respectively. The instruments collected initial datasets during two snowstorm events and two snow shower events in March 2017. The radar scan strategy was a combination of PPI scans at 4 elevation angles (10, 20, 45, and 60°) and RHI scans in polarimetry mode, and zenith pointing with Doppler spectra collection. During the snowstorm events the radar observed relatively larger ZDR (1-1.5 dB) and enhanced KDP (1-2 ° km-1) at heights corresponding to a plate/dendrite crystal growth regime. The Doppler spectra showed that slower-falling particles ( 1 m s-1). The weakly increased ZDR could be produced by large, faster falling particles such as quasi-spherical aggregates, while the enhanced KDP could be produced by highly-oriented oblate, slowly-falling particles. Below 2 km altitude, measurements of dual wavelength ratio (DWR) based on Ka and S-band reflectivities from the KASPR and NEXRAD radars were available. Larger DWR (>10 dB) suggested

  9. Determination of radar MTF

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  10. Atomic-Monolayer MoS2 Band-to-Band Tunneling Field-Effect Transistor

    KAUST Repository

    Lan, Yann Wen

    2016-09-05

    The experimental observation of band-to-band tunneling in novel tunneling field-effect transistors utilizing a monolayer of MoS2 as the conducting channel is demonstrated. Our results indicate that the strong gate-coupling efficiency enabled by two-dimensional materials, such as monolayer MoS2, results in the direct manifestation of a band-to-band tunneling current and an ambipolar transport.

  11. From ASCAT to Sentinel-1: Soil Moisture Monitoring using European C-Band Radars

    Science.gov (United States)

    Wagner, Wolfgang; Bauer-Marschallinger, Bernhard; Hochstöger, Simon

    2016-04-01

    The Advanced Scatterometer (ASCAT) is a C-Band radar instrument flown on board of the series of three METOP satellites. Albeit not operating in one of the more favorable longer wavelength ranges (S, L or P-band) as the dedicated Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) missions, it is one of main microwave sensors used for monitoring of soil moisture on a global scale. Its attractiveness for soil moisture monitoring applications stems from its operational status, high radiometric accuracy and stability, short revisit time, multiple viewing directions and long heritage (Wagner et al. 2013). From an application perspective, its main limitation is its spatial resolution of about 25 km, which does not allow resolving soil moisture patterns driven by smaller-scale hydrometeorological processes (e.g. convective precipitation, runoff patterns, etc.) that are themselves related to highly variable land surface characteristics (soil characteristics, topography, vegetation cover, etc.). Fortunately, the technique of aperture synthesis allows to significantly improve the spatial resolution of spaceborne radar instruments up to the meter scale. Yet, past Synthetic Aperture Radar (SAR) missions had not yet been designed to achieve a short revisit time required for soil moisture monitoring. This has only changed recently with the development and launch of SMAP (Entekhabi et al. 2010) and Sentinel-1 (Hornacek et al. 2012). Unfortunately, the SMAP radar failed only after a few months of operations, which leaves Sentinel-1 as the only currently operational SAR mission capable of delivering high-resolution radar observations with a revisit time of about three days for Europe, about weekly for most crop growing regions worldwide, and about bi-weekly to monthly over the rest of the land surface area. Like ASCAT, Sentinel-1 acquires C-band backscatter data in VV polarization over land. Therefore, for the interpretation of both ASCAT and Sentinel-1

  12. Política(s linguística(s e questões de poder

    Directory of Open Access Journals (Sweden)

    Cristine Gorski Severo

    2013-08-01

    Full Text Available O texto apresenta e discute os conceitos de poder e de política no campo de saber intitulado “Política Linguística”. Para tanto, inicialmente apresenta e discute a heterogeneidade e complexidade do campo, discorrendo sobre os conceitos de Política e Planejamento Linguísticos. Em seguida, apresenta os trabalhos genealógicos do filósofo francês Michel Foucault acerca da relação entre poder, saber e política. Para fins de discussão, o artigo apresenta uma série de casos, tanto reais como possíveis, de aplicação e intervenção do campo de Política Linguística, com vistas tanto a discutir a noção de poder em conceitos e metodologias utilizadas pela área de saber, como a expandir o lócus de intervenção da disciplina a partir de possíveis contribuições de Michel Foucault sobre a dinâmica das relações de poder aplicada aos estudos das relações entre as línguas, as línguas e os sujeitos, as línguas e a tecnologia, e as línguas e uma dada geopolítica.

  13. Proceedings of the COST 75 final seminar on advanced weather radar systems; Beitraege des Instituts zum COST 75 final seminar on advanced weather radar systems

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, R.; Flender, F.; Hagen, M.; Hoeller, H.; Keil, C.; Meischner, P.

    1998-07-01

    Across Europe more than 110 weather radars are in operation. More than 60 of them are Doppler radars and this number is increasing steadily. Doppler systems are becoming an operational standard. Most systems operate in C-band, with the exception of the Spanish radar network which is composed of S-band Doppler radars. Radar product composites are available for Scandinavia and Central Europe. National networks exist for the UK, France and Spain. Europe further is fortunate to have 8 polarimetric Doppler radars used mainly for research. In Italy some of those systems are used also for operational nowcasting applications for dedicated customers. The Chilbolton multiparameter Doppler radar operates at S-band. (orig.)

  14. A visibilidade política na série The Crown

    Directory of Open Access Journals (Sweden)

    Giovana dos Passos Colling

    2018-02-01

    Full Text Available O presente trabalho tem por objetivo compreender como se configura a visibilidade política na trama da série The Crown, produzida pela Netflix, por meio da análise dos três primeiros episódios. A partir do enredo da série, que conta a história da família real britânica na época em que a Raínha Elizabeth II assume o trono e suas novas responsabilidades políticas, é possível perceber e analisar as relações de poder entre a política, a sociedade e a mídia, além de temáticas como imagem pública, escândalo político, relações políticas entre países e discurso midiático. A análise de conteúdo se dá a partir dos autores Gomes, Thompson e Weber. Assim, torna-se perceptível a indissociabilidade entre a mídia, a sociedade e a política para a manutenção de um governo estável, que se utilizando da visibilidade midiática de maneira favorável, estabelece uma comunicação eficiente e uma imagem pública forte e positiva.

  15. 77 FR 48097 - Operation of Radar Systems in the 76-77 GHz Band

    Science.gov (United States)

    2012-08-13

    ... modify the emission limits for vehicular radar systems operating within the 76-77 GHz band. Specifically.... 15.253 of the rules for vehicular radar systems operating in the 76-77 GHz band. Vehicular radars can... sensors operating in the 76-77 GHz band, the spectrum shall be investigated up to 231 GHz. (f) Fundamental...

  16. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  17. L-band brightness temperature disaggregation for use with S-band and C-band radiometer data for WCOM

    Science.gov (United States)

    Yao, P.; Shi, J.; Zhao, T.; Cosh, M. H.; Bindlish, R.

    2017-12-01

    There are two passive microwave sensors onboard the Water Cycle Observation Mission (WCOM), which includes a synthetic aperture radiometer operating at L-S-C bands and a scanning microwave radiometer operating from C- to W-bands. It provides a unique opportunity to disaggregate L-band brightness temperature (soil moisture) with S-band C-bands radiometer data. In this study, passive-only downscaling methodologies are developed and evaluated. Based on the radiative transfer modeling, it was found that the TBs (brightness temperature) between the L-band and S-band exhibit a linear relationship, and there is an exponential relationship between L-band and C-band. We carried out the downscaling results by two methods: (1) downscaling with L-S-C band passive measurements with the same incidence angle from payload IMI; (2) downscaling with L-C band passive measurements with different incidence angle from payloads IMI and PMI. The downscaling method with L-S bands with the same incident angle was first evaluated using SMEX02 data. The RMSE are 2.69 K and 1.52 K for H and V polarization respectively. The downscaling method with L-C bands is developed with different incident angles using SMEX03 data. The RMSE are 2.97 K and 2.68 K for H and V polarization respectively. These results showed that high-resolution L-band brightness temperature and soil moisture products could be generated from the future WCOM passive-only observations.

  18. Challenges in X-band Weather Radar Data Calibration

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Rasmussen, Michael R.

    2009-01-01

    Application of weather radar data in urban hydrology is evolving and radar data is now applied for both modelling, analysis and real time control purposes. In these contexts, it is all-important that the radar data well calibrated and adjusted in order to obtain valid quantitative precipitation e...... estimates. This paper compares two calibration procedures for a small marine X-band radar by comparing radar data with rain gauge data. Validation shows a very good consensus with regards to precipitation volumes, but more diverse results on peak rain intensities.......Application of weather radar data in urban hydrology is evolving and radar data is now applied for both modelling, analysis and real time control purposes. In these contexts, it is all-important that the radar data well calibrated and adjusted in order to obtain valid quantitative precipitation...

  19. Development of Method for X-band Weather Radar Calibration

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ellerbæk; Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2013-01-01

    Calibration of the X-band LAWR (Local Area Weather Radar) is traditionally based on an assumed linear relation between the LAWRradar output and the rainfall intensity. However, closer inspections of the data reveal that the validity of this linear assumption is doubtful. Previous studies of this ......Calibration of the X-band LAWR (Local Area Weather Radar) is traditionally based on an assumed linear relation between the LAWRradar output and the rainfall intensity. However, closer inspections of the data reveal that the validity of this linear assumption is doubtful. Previous studies...... of this type of weather radar have also illustrated that the radar commonly has difficulties in estimating high rain rates. Therefore, a new radar–rainfall transformation model and a calibration method have been developed. The new method is based on nonlinear assumptions and is aimed at describing the whole...

  20. Developing Lightning Prediction Tools for the CCAFS Dual-Polarimetric Radar

    Science.gov (United States)

    Petersen, W. A.; Carey, L. D.; Deierling, W.; Johnson, E.; Bateman, M.

    2009-01-01

    ensuing lightning in the sub-tropical/tropical convection typical of the southeastern U.S., Maritime Continent, and southwestern Amazon. The polarimetric signatures detected in this setting provide a basis for automated 3-D detection of hydrometeor types in fuzzy logic hydrometeor identification algorithms (HID). Our working hypothesis is that improvement in lightning onset warning lead time and specificity for a given storm, relative to application of a Z-threshold algorithm, should arise as a consequence of the ability of dual-polarimetric radar to unambiguously detect and identify (through HID algorithms) the updraft elevation of rain-water cores above the freezing level and subsequent onset of drop freezing, riming, and robust mixed phase processes leading to significant charge separation and lightning. This type of algorithm, though dependent on the quality of the polarimetric data should be less susceptible to variable Z-calibration that can impact a given Z-threshold approach. To facilitate development of the algorithm while the 45WS dual-pol radar is in its current test stages and to evaluate the impact of polarimetric data quality (e.g., modified scan parameters and sampling) on the ensuing algorithms, we are using the ARMOR C-band dual-pol radar in Huntsville combined with N. Alabama LMA data and ARMOR HID algorithms [NCAR algorithm modified for application at C-band] in a testbed fashion. For lightning cessation we are revisiting the application of differential propagation phase variables for the monitoring of ice crystal alignment driven by in-cloud electric fields combined with metrics of ice water path (i.e., vertically integrated reflectivity). Importantly it should be noted that this approach is still very much a research topic and as such, we will explore operational applications that involve radar frequencies other than C-Band by using the UAH MAX X-band dual-pol radar in slow staring modes.

  1. Raindrop Size Distribution in Different Climatic Regimes from Disdrometer and Dual-Polarized Radar Analysis.

    Science.gov (United States)

    Bringi, V. N.; Chandrasekar, V.; Hubbert, J.; Gorgucci, E.; Randeu, W. L.; Schoenhuber, M.

    2003-01-01

    The application of polarimetric radar data to the retrieval of raindrop size distribution parameters and rain rate in samples of convective and stratiform rain types is presented. Data from the Colorado State University (CSU), CHILL, NCAR S-band polarimetric (S-Pol), and NASA Kwajalein radars are analyzed for the statistics and functional relation of these parameters with rain rate. Surface drop size distribution measurements using two different disdrometers (2D video and RD-69) from a number of climatic regimes are analyzed and compared with the radar retrievals in a statistical and functional approach. The composite statistics based on disdrometer and radar retrievals suggest that, on average, the two parameters (generalized intercept and median volume diameter) for stratiform rain distributions lie on a straight line with negative slope, which appears to be consistent with variations in the microphysics of stratiform precipitation (melting of larger, dry snow particles versus smaller, rimed ice particles). In convective rain, `maritime-like' and `continental-like' clusters could be identified in the same two-parameter space that are consistent with the different multiplicative coefficients in the Z = aR1.5 relations quoted in the literature for maritime and continental regimes.

  2. Advancing NASA’s AirMOSS P-Band Radar Root Zone Soil Moisture Retrieval Algorithm via Incorporation of Richards’ Equation

    Directory of Open Access Journals (Sweden)

    Morteza Sadeghi

    2016-12-01

    Full Text Available P-band radar remote sensing applied during the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS mission has shown great potential for estimation of root zone soil moisture. When retrieving the soil moisture profile (SMP from P-band radar observations, a mathematical function describing the vertical moisture distribution is required. Because only a limited number of observations are available, the number of free parameters of the mathematical model must not exceed the number of observed data. For this reason, an empirical quadratic function (second order polynomial is currently applied in the AirMOSS inversion algorithm to retrieve the SMP. The three free parameters of the polynomial are retrieved for each AirMOSS pixel using three backscatter observations (i.e., one frequency at three polarizations of Horizontal-Horizontal, Vertical-Vertical and Horizontal-Vertical. In this paper, a more realistic, physically-based SMP model containing three free parameters is derived, based on a solution to Richards’ equation for unsaturated flow in soils. Evaluation of the new SMP model based on both numerical simulations and measured data revealed that it exhibits greater flexibility for fitting measured and simulated SMPs than the currently applied polynomial. It is also demonstrated that the new SMP model can be reduced to a second order polynomial at the expense of fitting accuracy.

  3. CAMEX-4 MOBILE X-BAND POLARIMETRIC WEATHER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobile X-band Polarimetric Weather Radar on Wheels (X-POW)is a Doppler scanning radar operating at 9.3 GHz.with horizontal and vertical polarization. Used for...

  4. Twitter : La xarxa social més política

    OpenAIRE

    Rodríguez Plaza, Susanna

    2017-01-01

    Anàlisi de l'ús de Twitter en política i estudi de l'activitat de diferents perfils de polítics catalans al llarg de la investidura del 2016. Observació de quin és el model comunicatiu que utilitzen, com creen conversa i quin impacte generen en els seus seguidors. Analyze the use of Twitter in politics studying the activity of different profiles of catalan politicians during the 2016 investiture. To observe what kind of communication they use, and how they create conversations and what imp...

  5. Ground Radar Polarimetric Observations of High-Frequency Earth-Space Communication Links

    Science.gov (United States)

    Bolen, Steve; Chandrasekar, V.; Benjamin, Andrew

    2002-01-01

    Strategic roadmaps for NASA's Human Exploration and Development of Space (REDS) enterprise support near-term high-frequency communication systems that provide moderate to high data rates with dependable service. Near-earth and human planetary exploration will baseline Ka-Band, but may ultimately require the use of even higher frequencies. Increased commercial demand on low-frequency earth-space bands has also led to increased interest in the use of higher frequencies in regions like K u - and K,- band. Data is taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), which operates at 13.8 GHz, and the true radar reflectivity profile is determined along the PR beam via low-frequency ground based polarimetric observations. The specific differential phase (Kdp) is measured along the beam and a theoretical model is used to determine the expected specific attenuation (k). This technique, called the k-Kdp method, uses a Fuzzy-Logic model to determine the hydrometeor type along the PR beam from which the appropriate k-Kdp relationship is used to determine k and, ultimately, the total path-integrated attenuation (PIA) on PR measurements. Measurements from PR and the NCAR S-POL radar were made during the TEFLUN-B experiment that took place near Melbourne, FL in 1998, and the TRMM-LBA campaign near Ji-Parana, Brazil in 1999.

  6. Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

    Directory of Open Access Journals (Sweden)

    Pottier E.

    2010-06-01

    Full Text Available SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height

  7. Development and Application of integrated monitoring platform for the Doppler Weather SA-BAND Radar

    Science.gov (United States)

    Zhang, Q.; Sun, J.; Zhao, C. C.; Chen, H. Y.

    2017-10-01

    The doppler weather SA-band radar is an important part of modern meteorological observation methods, monitoring the running status of radar and the data transmission is important.This paper introduced the composition of radar system and classification of radar data,analysed the characteristics and laws of the radar when is normal or abnormal. Using Macromedia Dreamweaver and PHP, developed the integrated monitoring platform for the doppler weather SA-band radar which could monitor the real-time radar system running status and important performance indicators such as radar power,status parameters and others on Web page,and when the status is abnormal it will trigger the audio alarm.

  8. Impact of Surface Soil Moisture Variations on Radar Altimetry Echoes at Ku and Ka Bands in Semi-Arid Areas

    Directory of Open Access Journals (Sweden)

    Christophe Fatras

    2018-04-01

    Full Text Available Radar altimetry provides information on the topography of the Earth surface. It is commonly used for the monitoring not only sea surface height but also ice sheets topography and inland water levels. The radar altimetry backscattering coefficient, which depends on surface roughness and water content, can be related to surface properties such as surface soil moisture content. In this study, the influence of surface soil moisture on the radar altimetry echo and backscattering coefficient is analyzed over semi-arid areas. A semi-empirical model of the soil’s complex dielectric permittivity that takes into account that small-scale roughness and large-scale topography was developed to simulate the radar echoes. It was validated using waveforms acquired at Ku and Ka-bands by ENVISAT RA-2 and SARAL AltiKa respectively over several sites in Mali. Correlation coefficients ranging from 0.66 to 0.94 at Ku-band and from 0.27 to 0.96 at Ka-band were found. The increase in surface soil moisture from 0.02 to 0.4 (i.e., the typical range of variations in semi-arid areas increase the backscattering from 10 to 15 dB between the core of the dry and the maximum of the rainy seasons.

  9. Digital Conically Scanned L-Band Radar, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort seeks to develop a digitally steered polarimetric phased array L-Band radar utilizing a novel, high performance architecture leveraging recent...

  10. Quantitative analysis of X-band weather radar attenuation correction accuracy

    NARCIS (Netherlands)

    Berne, A.D.; Uijlenhoet, R.

    2006-01-01

    At short wavelengths, especially C-, X-, and K-band, weather radar signals arc attenuated by the precipitation along their paths. This constitutes a major source of error for radar rainfall estimation, in particular for intense precipitation. A recently developed stochastic simulator of range

  11. Synthetic aperture radar capabilities in development

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  12. Actitud 2.0: la política más allá de los blogs

    Directory of Open Access Journals (Sweden)

    Roc Fages Ramió

    2008-09-01

    Full Text Available La Actitud 2.0 es el elemento clave para aprovechar las posibilidades que el trabajo y la relación en red proporciona a empresas, organizaciones y administraciones. Si una persona es 2.0 quiere decir que utiliza las herramientas de la Web 2.0 para generar red y obtener beneficios personales o profesionales, individuales y colectivos, a partir de compartir conocimiento.Este artículo empieza definiendo la Web 2.0 para demostrar que sin una actitud hacia este fenómeno el concepto no puede llegar a ningún sitio. A partir de esta conceptualización, el documento desarrolla la aplicación de la Actitud 2.0 a nivel de la política. Aquello que se conoce como Política 2.0, dice el texto, está aplicándose más desde el punto de vista de la ciudadanía que de los mismos políticos. Por lo tanto, la Política 2.0 crea una nueva forma de hacer política por parte de los ciudadanos. Eso quiere decir que éstos intentan generar una red de la que los políticos muchas veces no forman parte, incluso aunque se hayan integrado en el ámbito 2.0. El problema, pues, es que muchos políticos supuestamente 2.0 sólo utilizan las herramientas -blogs, Facebook, YouTube, Twitter...- sin entrar a fondo en las capacidades de la red. Porque, de hecho, la Política 2.0 les permitiría poder conocer, compartir y escuchar más directamente las necesidades y los intereses de la misma ciudadanía.Llegados a este punto, y después de repasar algunas iniciativas interesantes de Política 2.0, el artículo acaba destacando la importancia de la nueva generación de nativos digitales, de personas que han nacido con el fenómeno 2.0 integrado, la generación de la Nintendo. Este grupo de jóvenes son los que tienen que marcar las tendencias que en un futuro muy inmediato serán realidades: trabajo y relación en red elevados al máximo exponente. Por lo tanto, les tiene que quedar claro a los políticos que, hoy por hoy, la Política 2.0 se tiene que hacer con Actitud 2.0 y,

  13. Full L-S Band Telemetry System

    National Research Council Canada - National Science Library

    Jensen, Michael

    2001-01-01

    Recent changes in spectrum availability as well as higher demands for spectrum have motivated the development of telemetry transmit systems capable of fully operating over both L and S telemetry bands...

  14. Full L-S Band Telemetry System

    National Research Council Canada - National Science Library

    Jensen, Michael

    2003-01-01

    Recent changes in spectrum availability as well as higher demands for spectrum have motivated the development of telemetry transmit systems capable of fully operating over both L and S telemetry bands...

  15. Full L-S Band Telemetry System

    National Research Council Canada - National Science Library

    Jensen, Michael

    2002-01-01

    Recent changes in spectrum availability as well as higher demands for spectrum have motivated the development of telemetry transmit systems capable of fully operating over both L and S telemetry bands...

  16. Compact 1 × 2 and 2 × 2 Dual Polarized Series-Fed Antenna Array for X-Band Airborne Synthetic Aperture Radar Applications

    Directory of Open Access Journals (Sweden)

    Venkata Kishore Kothapudi

    2018-04-01

    Full Text Available In this paper, compact linear dual polarized series-fed 1 × 2 linear and 2 × 2 planar arrays antennas for airborne SAR applications are proposed. The proposed antenna design consists of a square radiating patch that is placed on top of the substrate, a quarter wave transformer and 50-Ω matched transformer. Matching between a radiating patch and the 50-Ω microstrip line is accomplished through a direct coupled-feed technique with the help of an impedance inverter (λ/4 impedance transformer placed at both horizontal and vertical planes, in the case of the 2 × 2 planar array. The overall size for the prototype-1 and prototype-2 fabricated antennas are 1.9305 × 0.9652 × 0.05106 λ03 and 1.9305 × 1.9305 × 0.05106 λ03, respectively. The fabricated structure has been tested, and the experimental results are similar to the simulated ones. The CST MWS simulated and vector network analyzer measured reflection coefficient (S11 results were compared, and they indicate that the proposed antenna prototype-1 yields the impedance bandwidth > 140 MHz (9.56–9.72 GHz defined by S11 140 MHz for all the individual ports. The surface currents and the E- and H-field distributions were studied for a better understanding of the polarization mechanism. The measured results of the proposed dual polarized antenna were in accordance with the simulated analysis and showed good performance of the S-parameters and radiation patterns (co-pol and cross-pol, gain, efficiency, front-to-back ratio, half-power beam width at the resonant frequency. With these features and its compact size, the proposed antenna will be suitable for X-band airborne synthetic aperture radar applications.

  17. Magnetron based high energy S-band linac system

    International Nuclear Information System (INIS)

    Tiwari, T.; Krishnan, R.; Phatangare, Manoj

    2012-01-01

    This paper deals with the study of magnetron based high energy S-band linear accelerator (linac) system operating at spot frequency 2.998 GHz. The energy and dose are two important parameters of linac system which depend on input power of microwave source and length of linac tube. Here the author has studied how these parameters can be improved for side coupled standing wave S-band linac system

  18. High-power test of S-band klystron for long-pulse operation

    International Nuclear Information System (INIS)

    Morii, Y.; Oshita, E.; Abe, S.; Keishi, T.; Tomimasu, T.; Ohkubo, Y.; Yoshinao, M.; Yonezawa, H.

    1994-01-01

    FELI(Free Electron Laser Research Institute, Inc.) is constructing a free electron laser facility covering from 20μm (infra red region) to 0.35μm (ultra violet region), using an S-band linac. The linac is commissioning now. An RF system of the linac for FELs is required of long pulse duration and high stability. S-band klystrons (TOSHIBA E3729) of the FELI linac are operated in three pulse operation modes (pulse width and peak RF power; 24μs-24MW, 12.5μs-34MW, 0.5μs-70MW). The S-band klystron and its modulator were combined to test their performance. The high power test results of the S-band klystron are summarized in this paper. (author)

  19. Ultra-High Gradient S-band Linac for Laboratory and Industrial Applications

    Science.gov (United States)

    Faillace, L.; Agustsson, R.; Dolgashev, V.; Frigola, P.; Murokh, A.; Rosenzweig, J.; Yakimenko, V.

    2010-11-01

    A strong demand for high gradient structures arises from the limited real estate available for linear accelerators. RadiaBeam Technologies is developing a Doubled Energy Compact Accelerator (DECA) structure: an S-band standing wave electron linac designed to operate at accelerating gradients of up to 50 MV/m. In this paper, we present the radio-frequency design of the DECA S-band accelerating structure, operating at 2.856 GHz in the π-mode. The structure design is heavily influenced by NLC collaboration experience with ultra high gradient X-band structures; S-band, however, is chosen to take advantage of commonly available high power S-band klystrons.

  20. Sensitivity of C-Band Polarimetric Radar-Based Drop Size Distribution Measurements to Maximum Diameter Assumptions

    Science.gov (United States)

    Carey, Lawrence D.; Petersen, Walter A.

    2011-01-01

    similar modeled retrieval errors at S-band and X-band where the sensitivity to D(sub max) is expected to be less. The impact of D(sub max) assumptions to the retrieval of other DSD parameters such as Nw, the liquid water content normalized intercept parameter, are also explored. Likely implications for DSD retrievals using C-band polarimetric radar for GPM are assessed by considering current community knowledge regarding D(sub max) and quantifying the statistical distribution of Z(sub dr) from ARMOR over a large variety of meteorological conditions. Based on these results and the prevalence of C-band polarimetric radars worldwide, a call for more emphasis on constraining our observational estimate of D(sub max) within a typical radar resolution volume is made

  1. Band structural properties of MoS2 (molybdenite)

    International Nuclear Information System (INIS)

    Gupta, V.P.

    1980-01-01

    Semiconductivity and superconductivity in MoS 2 (molybdenite) can be understood in terms of the band structure of MoS 2 . The band structural properties of MoS 2 are presented here. The energy dependence of nsub(eff) and epsilon(infinity)sub(eff) is investigated. Using calculated values of nsub(eff) and epsilon(infinity)sub(eff), the Penn gap has been determined. The value thus obtained is shown to be in good agreement with the reflectivity data and also with the value obtained from the band structure. The Ravindra and Srivastava formula has been shown to give values for the isobaric temperature gradient of Esub(G)[(deltaEsub(G)/deltaT)sub(P)], which are in agreement with the experimental data, and the contribution to (deltaEsub(G)/deltaT)sub(P) due to the electron lattice interaction has been evaluated. In addition, the electronic polarizability has been calculated using a modified Lorentz-Lorenz relation. (author)

  2. Analysis of X-band radar images for the detection of the reflected and diffracted waves in coastal zones

    Science.gov (United States)

    Ludeno, Giovanni; Natale, Antonio; Soldovieri, Francesco; Vicinanza, Diego; Serafino, Francesco

    2014-05-01

    .2, pp. 231-235, April 2010. [2] Senet, C. M., Seemann, J., Flampouris, S., and Ziemer, F. (2008). Determination of bathymetric and current maps by the method DiSC based on the analysis of nautical X-Band radar image sequences of the sea surface (November 2007). IEEE Trans. on Geoscience and Remote Sensing, 46(8), 2267-2279. [3] F. Ziemer, and W. Rosenthal, "Directional spectra from shipboard navigation radar during LEWEX". Directional Ocean Wave Spectra: Measuring, Modeling, Predicting, and Applying, 1991 R. C. Beal, Ed., The Johns Hopkins University Press, pp. 125-127. [4] Weimin Huang ; Gill, E.," Surface Current Measurement Under Low Sea State Using Dual Polarized X-Band Nautical Radar", Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of, vol. 5, no.6, page 186-1873, 2012.

  3. The Keenan and Wing bands in S stars

    International Nuclear Information System (INIS)

    Lambert, D.L.; Clegg, R.E.S.

    1980-01-01

    New observations of the near infrared spectra of S stars are presented as part of a survey of the unidentified Keenan and Wing bands. Bandhead wavelengths accurate to 0.5 A are presented. A new band is found at 9014 A. The bands are not present in normal M giants and dwarfs. Laboratory spectroscopy of heavy element oxides is reported. Several new identifications are proposed. The 10 300 A Wing band is identified with the Δv = - 1 sequence of the ZrO 9300 A Δv = 0 bands. The ZrO B 1 PI-A 1 Δ (Δv = 0) system may be responsible for either the 9736 A or the 10 515 A Wing bands. Two new bands in the near infrared at 8219 and 8235 A are provided by CeO. A new band with heads at 7503 and 7509 A in a spectrum of R And is tentatively attributed to YS. A band at 8268 A in M stars is the TiO delta(2-1) head. The 8610 A Keenan band is not due to CrH. Potential carriers of the Keenan and Wing bands are reviewed. It is suggested that the heavy element sulphides and, perhaps, chlorides are leading candidates. Identification of YS in R And may provide the first evidence for these sulphides. ZrS is a leading candidate for which laboratory spectroscopy is needed. (author)

  4. El feudalismo político del sistema confesional libanés

    OpenAIRE

    Hana Jalloul

    2008-01-01

    Este articulo trata de desentrañar la dificultad del complejo sistema confesional libanés, un sistema obsoleto que a día de hoy sigue condicionando la vida de la población libanesa a nivel religioso, político, social y económico.

  5. Thaksin Shinawatra y el sistema político tailandés, 2001-2006

    OpenAIRE

    Toledo Beltrán, J. Daniel

    2014-01-01

    La irrupción de Thaksin Shinawatra en el máximo escenario político nacional, al triunfar en las elecciones generales de enero de 2001, representó un verdadero hito en la historia política contemporánea de Tailandia, no sólo porque ejemplifica una combinación exitosa entre negocios y política, tan propia de Tailandia, sino sobre todo porque, por la vía de la institucionalidad y cronograma democrático, impulsó una "Agenda Nacional" que, por un lado, generó amplias expectativas y apoyo de parte ...

  6. S-band and X-band integrated PWT photoelectron linacs

    International Nuclear Information System (INIS)

    Yu, D.; Newsham, D.; Zeng, J.; Rosenzweig, J.

    2001-01-01

    A compact high-energy injector, which has been developed by DULY Research Inc., will have wide scientific, industrial, and medical applications. The new photoelectron injector integrates the photocathode directly into a multicell linear accelerator. By focusing the beam with solenoids or permanent magnets, and producing high current with low emittance, high brightness and low energy spread are achieved. In addition to providing a small footprint and improved beam quality in an integrated structure, the compact system considerably simplifies external subsystems required to operate the photoelectron linac, including rf power transport, beam focusing, vacuum and cooling. The photoelectron linac employs an innovative Plane-Wave-Transformer (PWT) design, which provides strong cell-to-cell coupling, relaxes manufacturing tolerances and facilitates the attachment of external ports to the compact structure with minimal field interference. DULY Research Inc. under the support of the DOE Small Business Innovation Research (SBIR) program, has developed, constructed and installed a 20-MeV, S-band compact electron source at UCLA. Cold test results for this device are presented. DULY Research is also actively engaged in the development of an X-band photoelectron linear accelerator in a SBIR project. When completed, the higher frequency structure will be approximately three times smaller. Design considerations for this device are discussed following the S-band cold test results

  7. Spectrum Band Selection in Delay-QoS Constrained Cognitive Radio Networks

    KAUST Repository

    Yang, Yuli

    2014-01-01

    In this paper, a cognitive radio (CR) network with multiple spectrum bands available for secondary users (SUs) is considered. For the SU\\'s active spectrum-band selection, two criteria are developed. One is to select the band with the highest secondary channel power gain, and the other is to select the band with the lowest interference channel power gain to primary users (PUs). With the quality-of-service (QoS) requirement concerning delay, the effective capacity (EC) behaviors over secondary links are investigated for both criteria under two spectrum-sharing constraints. To begin by presenting full benefits in these criteria, the constraint imposed on the secondary transmitter (ST) is the average interference limitation to PUs only. Furthermore, taking into account the ST\\'s battery/energy budget, the ST is imposed by joint constraints on its average interference to PUs, as well as on its own average transmit power. For either constraint, we formulate the ST\\'s optimal transmit power allocation to maximize the SU\\'s EC with both band-selection criteria and, correspondingly, obtain the secondary\\'s power allocation and maximum EC in closed forms. Numerical results demonstrated subsequently substantiate the validity of our derivations and provide a powerful tool for the spectrum-band selection in CR networks with multiple bands available. © 1967-2012 IEEE.

  8. Radar detection of Vesta

    International Nuclear Information System (INIS)

    Ostro, S.J.; Cornell University, Ithaca, N.Y.); Campbell, D.B.; Pettengill, G.H.

    1980-01-01

    Asteroid 4 Vesta was detected on November 6, 1979 with the Arecibo Observatory's S-band (12.6-cm-wavelength) radar. The echo power spectrum, received in the circular polarization opposite to that transmitted, yields a radar cross section of (0.2 + or - 0.1)pi a-squared, for a 272 km. The data are too noisy to permit derivation of Vesta's rotation period

  9. Performance of a 150-MW S-band klystron

    International Nuclear Information System (INIS)

    Sprehn, D.; Phillips, R.M.; Caryotakis, G.

    1994-09-01

    As part of an international collaboration, the Stanford Linear Accelerator Center (SLAC) klystron group has designed, fabricated, and tested a 60-Hz, 3-μs, 150-MW S-band klystron built for Deutsches Elektronen Synchrotron (DESY). A test diode with a 535-kV, 700-A electron beam was constructed to verify the gun operation. The first klystron was built and successfully met design specifications. The 375-MW electron beam represents a new record for SLAC accelerator klystrons in terms of voltage, current, energy, and ruggedness of design. The rf output power is a 150% increase over the S-band tubes currently used in the two-mile-long linear accelerator at SLAC. This paper discusses design issues and experimental results of the diode and klystron

  10. Retrieval of Wind Speed Using an L-band Synthetic Aperture Radar

    DEFF Research Database (Denmark)

    Monaldo, Frank M.; Thompson, Donald R.; Badger, Merete

    2007-01-01

    Retrieval of wind speed using L-band synthetic aperture radar (SAR) is both an old and new endeavor. Although the Seasat L-band SAR in 1978 was not well calibrated, early results indicated a strong relationship between observed SAR image intensity and wind speed. The JERS-1 L-band SAR had limited...

  11. X-Band wave radar system for monitoring and risk management of the coastal infrastructures

    Science.gov (United States)

    Ludeno, Giovanni; Soldovieri, Francesco; Serafino, Francesco

    2017-04-01

    waves from the coastal infrastructures, e.g. from the harbor jetties. In fact, the reflected waves may significantly complicate the harbour activities (e.g., berthing operations), as they interfere with the oncoming waves thus creating a confused sea [2]. References [1] G. Ludeno, C. Brandini, C. Lugni, D. Arturi, A. Natale, F. Soldovieri, B. Gozzini, F. Serafino, "Remocean System for the Detection of the Reflected Waves from the Costa Concordia Ship Wreck", IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Vol.7, no.3, pp.3011-3018, July 2014. [2] G. Ludeno, F. Reale, F. Dentale, E. Pugliese Carratelli, A. Natale, F. Soldovieri, F. Serafino "An X-Band Radar System for Bathymetry and Wave Field Analysis in Harbor Area", Sensors, Vol.15, no.1, pp. 1691-1707, January 2015. [3] F. Raffa, G. Ludeno, B. Patti, F. Soldovieri, S. Mazzola, and F. Serafino, "X-band wave radar for coastal upwelling detection off the southern coast of Sicily.", Journal of Atmospheric and Oceanic Technology, January 2017, Vol. 34, No. 1, Published online on 22 Dec 2016.

  12. Políticas da Terra: existe um novo discurso ambiental pós Rio +20?

    Directory of Open Access Journals (Sweden)

    Juliana Wenceslau

    Full Text Available Políticas públicas envolvem a construção de significado através de discursos, que caracterizam redes semânticas complexas, articulando diferentes pressupostos, conceitos e hipóteses. O objetivo deste artigo é contribuir para o debate sobre a evolução recente da política ambiental, indagando em que medida os debates que marcaram a Rio +20 caracterizam uma ruptura com os quatro discursos predominantes na política ambiental ao longo dos últimos 40 anos. São eles: sobrevivencialismo, resolução de problemas, sustentabilidade e radicalismo verde. Esses discursos são diferentes em seus pressupostos ontológicos (mais realista ou mais nominalista; nas suposições sobre a natureza dos relacionamentos com o meio ambiente (baseados em competição ou em cooperação; na perspectiva que assumem sobre os atores (individualistas ou coletivistas; fortes ou fracos; e nas metáforas que utilizam para defender seus pontos de vista (DRYZEK, 1997. Algumas perguntas também são colocadas para avaliar o impacto e plausibilidade do discurso: que política é associada a ele; seu efeito nas políticas públicas e nas instituições; os argumentos dos críticos; e as falhas reveladas pelas evidências e argumentos. A análise do discurso da Rio +20 foi baseada no documento final da conferência "The Future We Want". Concluímos que os debates da conferência agregam dois grandes discursos: resolução de problemas e sustentabilidade. Alguns efeitos antecipados da Rio +20 são: a melhoria das estatísticas ambientais; aumento de empregos ligados à economia verde; e adoção de políticas regulatórias que modifiquem os preços relativos do uso dos recursos e internalizem os custos das externalidades ambientais.

  13. Band alignment at the Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4}/CdS interface

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Richard; Barkhouse, Aaron; Gunawan, Oki; Shin, Byungha; Copel, Matt; Hopstaken, Marinus; Mitzi, David B [IBM TJ Watson Research Center, P.O. Box 218, Yorktown Hts., New York 10598 (United States)

    2011-06-20

    Energy band alignments between CdS and Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4} (CZTSSe) grown via solution-based and vacuum-based deposition routes were studied as a function of the [S]/[S+Se] ratio with femtosecond laser ultraviolet photoelectron spectroscopy, photoluminescence, medium energy ion scattering, and secondary ion mass spectrometry. Band bending in the underlying CZTSSe layer was measured via pump/probe photovoltage shifts of the photoelectron spectra and offsets were determined with photoemission under flat band conditions. Increasing the S content of the CZTSSe films produces a valence edge shift to higher binding energy and increases the CZTSSe band gap. In all cases, the CdS conduction band offsets were spikes.

  14. High Efficiency S-Band 20 Watt Amplifier

    Data.gov (United States)

    National Aeronautics and Space Administration — This project includes the design and build of a prototype 20 W, high efficiency, S-Band amplifier.   The design will incorporate the latest semiconductor technology,...

  15. System Realization of Broad Band Digital Beam Forming for Digital Array Radar

    Directory of Open Access Journals (Sweden)

    Wang Feng

    2013-09-01

    Full Text Available Broad band Digital Beam Forming (DBF is the key technique for the realization of Digital Array Radar (DAR. We propose the method of combination realization of the channel equalization and DBF time delay filter function by using adaptive Sample Matrix Inversion algorithm. The broad band DBF function is realized on a new DBF module based on parallel fiber optic engines and Field Program Gate Array (FPGA. Good performance is achieved when it is used to some radar products.

  16. Modulators for the S-band test linac at DESY

    Science.gov (United States)

    Bieler, M.; Choroba, S.; Hameister, J.; Lewin, H.-Ch.

    1995-07-01

    The development of adequate modulators for high peak power klystrons is one of the focus points for linear collider R&D programs. For the DESY/THD S-band linear collider study 150 MW rf-pulse power at 50 Hz repetition rate and 3 μs pulse duration is required [1]. Two different modulator schemes are under investigation. One is the conventional line type pulser, using a pulse forming network and a step up transformer, the other one is a hard tube pulser, using a dc power source at the full klystron voltage and a switch tube. This paper is focused on the modulator development for the S-band Test Linac at DESY. After a short overview over the test linac and a brief description of the 150 MW S-band klystron the circuitry of the line type pulse (LTP) is given. A hard tube pulser (HTP), which switches the high voltage directly from a storage capacitor to the klystron, has been built up at DESY. Circuitry and the results of the commissioning of the switch tube are reported.

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  18. Resonant enhancement of band-to-band tunneling in in-plane MoS2/WS2 heterojunctions

    Science.gov (United States)

    Kuroda, Tatsuya; Mori, Nobuya

    2018-04-01

    The band-to-band (BTB) tunneling current J through in-plane MoS2/WS2 heterojunctions is calculated by the nonequilibrium Green function method combined with tight-binding approximation. Types A and B of band configurations are considered. For type-A (type-B) heterojunctions, a potential notch exists (or is absent) at the heterointerface. Both type-A and type-B MoS2/WS2 heterojunctions can support a higher BTB current than MoS2 and WS2 homojunctions. For type-A heterojunctions, the resonant enhancement of J occurs resulting in a significantly higher BTB tunneling current.

  19. Development of wide band digital receiver for atmospheric radars using COTS board based SDR

    Science.gov (United States)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    Digital receiver extracts the received echo signal information, and is a potential subsystem for atmospheric radar, also referred to as wind profiling radar (WPR), which provides the vertical profiles of 3-dimensional wind vector in the atmosphere. This paper presents the development of digital receiver using COTS board based Software Defined Radio technique, which can be used for atmospheric radars. The developmental work is being carried out at National Atmospheric Research Laboratory (NARL), Gadanki. The digital receiver consists of a commercially available software defined radio (SDR) board called as universal software radio peripheral B210 (USRP B210) and a personal computer. USRP B210 operates over a wider frequency range from 70 MHz to 6 GHz and hence can be used for variety of radars like Doppler weather radars operating in S/C bands, in addition to wind profiling radars operating in VHF, UHF and L bands. Due to the flexibility and re-configurability of SDR, where the component functionalities are implemented in software, it is easy to modify the software to receive the echoes and process them as per the requirement suitable for the type of the radar intended. Hence, USRP B210 board along with the computer forms a versatile digital receiver from 70 MHz to 6 GHz. It has an inbuilt direct conversion transceiver with two transmit and two receive channels, which can be operated in fully coherent 2x2 MIMO fashion and thus it can be used as a two channel receiver. Multiple USRP B210 boards can be synchronized using the pulse per second (PPS) input provided on the board, to configure multi-channel digital receiver system. RF gain of the transceiver can be varied from 0 to 70 dB. The board can be controlled from the computer via USB 3.0 interface through USRP hardware driver (UHD), which is an open source cross platform driver. The USRP B210 board is connected to the personal computer through USB 3.0. Reference (10 MHz) clock signal from the radar master oscillator

  20. Broadband S-band class E HPA

    NARCIS (Netherlands)

    Wanum, M.; van Dijk, R.; de Hek, A.P.; van Vliet, Frank Edward

    2009-01-01

    A broadband class E High Power Amplifier (HPA) is presented. This HPA is designed to operate at S-band (2.75 to 3.75 GHz). A power added efficiency of 50% is obtained for the two stage amplifier with an output power of 35.5 dBm on a chip area of 5.25 times 2.8 mm2.

  1. Detection Range Estimation of UV Spectral Band Laser Radar

    Directory of Open Access Journals (Sweden)

    V. A. Gorodnichev

    2014-01-01

    Full Text Available Recently, has come into existence an interest in the systems operating in the ultra-violet (UF band of wavelengths, which use other spectral information (coefficients of reflection or radiation in UF range about location objects, than laser systems in the visible, near or average infrared bands. Thus, a point is not only to receive additional (in another spectral range information on location objects. Laser radiation in the UF spectral band of 0.315 – 0.4 microns is safer than laser radiation with the wavelengths of 0.38 – 1.4 microns.The work presents a comparative estimation of the detection systems range of laser radars in the UV and visible spectral bands for the following wavelengths of radiation:- UF band: 0.266 microns (the fourth harmonic of YAG-laser activated by neodymium ions, 0.308 microns (the XeCl-excimer laser, 0.355 microns (the third harmonic of YAG-laser activated by neodymium ions;- visible band: 0.532 microns (the second harmonic of YAG-laser activated by neodymium ions.Results of calculations show that for the horizontal pathway in the terrestrial atmosphere at the selected radiation wavelengths a detection range is in the range of 2510m – 5690 m.The maximum range of detection corresponds to the visible spectral band. A sweep range decreases with transition to the UF band. This is caused by the fact that with transition to the UF band there is a rise of atmosphere attenuation (generally, because of absorption by ozone, this effect being smoothed by reducing background radiation.In the UF band a wavelength of 0.355 microns is the most acceptable. For this wavelength a detection range is about 1,5 times less (in comparison with the visible band of 0.532 microns. However, this is the much more eye-safe wavelength. With transition to the UV band a detection range decreases not that much and can be compensated by changing parameters of transmitting or receiving channels of laser radar.

  2. Electronic structure of the misfit layer compound (SnS)(1.20)TiS2 : Band structure calculations and photoelectron spectra

    NARCIS (Netherlands)

    Fang, CM; deGroot, RA; Wiegers, GA; Haas, C

    1996-01-01

    In order to understand the electronic structure of the incommensurate misfit layer compound (SnS)(1.20)TiS2 we carried out an ab initio band structure calculation in the supercell approximation. The band structure is compared with that of the components 1T-TiS2 and hypothetical SnS with a similar

  3. Electronic structure of the misfit layer compound (SnS)1.20TiS2 : band structure calculations and photoelectron spectra

    NARCIS (Netherlands)

    Fang, C.M.; Groot, R.A. de; Wiegers, G.A.; Haas, C.

    1996-01-01

    In order to understand the electronic structure of the incommensurate misfit layer compound (SnS)1.20TiS2 we carried out an ab initio band structure calculation in the supercell approximation. The band structure is compared with that of the components 1T-TiS2 and hypothetical SnS with a similar

  4. Ka-Band ARM Zenith Radar Corrections Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Karen [Brookhaven National Lab. (BNL), Upton, NY (United States); Toto, Tami [Brookhaven National Lab. (BNL), Upton, NY (United States); Giangrande, Scott [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-10-15

    The KAZRCOR Value -added Product (VAP) performs several corrections to the ingested KAZR moments and also creates a significant detection mask for each radar mode. The VAP computes gaseous attenuation as a function of time and radial distance from the radar antenna, based on ambient meteorological observations, and corrects observed reflectivities for that effect. KAZRCOR also dealiases mean Doppler velocities to correct velocities whose magnitudes exceed the radar’s Nyquist velocity. Input KAZR data fields are passed through into the KAZRCOR output files, in their native time and range coordinates. Complementary corrected reflectivity and velocity fields are provided, along with a mask of significant detections and a number of data quality flags. This report covers the KAZRCOR VAP as applied to the original KAZR radars and the upgraded KAZR2 radars. Currently there are two separate code bases for the different radar versions, but once KAZR and KAZR2 data formats are harmonized, only a single code base will be required.

  5. Incidence angle normalization of radar backscatter data

    Science.gov (United States)

    NASA’s Soil Moisture Passive Active (SMAP) satellite (~2014) will include a radar system that will provide L-band multi-polarization backscatter at a constant incidence angle of 40º. During the pre-launch phase of the project there is a need for observations that will support the radar-based soil mo...

  6. Polímeros entrecruzados a base de PVC : síntesis, caracterización y propiedades

    OpenAIRE

    Hidalgo Fierro, Manuel

    1997-01-01

    La modificación de polímeros es uno de los métodos mas rápidos, económicos y eficaces para la obtención de materiales con propiedades mejoradas a partir de polímeros convencionales. En este trabajo se ha desarrollado la síntesis de polímeros entrecruzados a base de policloruro de vinilo, empleando para ello dos métodos bien diferenciados: en primer lugar, se han obtenido polímeros entrecruzados en un solo paso, mediante procesado reactivo en estado fundido con organosilanos, lo que confiere...

  7. W-band spaceborne radar observations of atmospheric river events

    Science.gov (United States)

    Matrosov, S. Y.

    2010-12-01

    While the main objective of the world first W-band radar aboard the CloudSat satellite is to provide vertically resolved information on clouds, it proved to be a valuable tool for observing precipitation. The CloudSat radar is generally able to resolve precipitating cloud systems in their vertical entirety. Although measurements from the liquid hydrometer layer containing rainfall are strongly attenuated, special retrieval approaches can be used to estimate rainfall parameters. These approaches are based on vertical gradients of observed radar reflectivity factor rather than on absolute estimates of reflectivity. Concurrent independent estimations of ice cloud parameters in the same vertical column allow characterization of precipitating systems and provide information on coupling between clouds and rainfall they produce. The potential of CloudSat for observations atmospheric river events affecting the West Coast of North America is evaluated. It is shown that spaceborne radar measurements can provide high resolution information on the height of the freezing level thus separating areas of rainfall and snowfall. CloudSat precipitation rate estimates complement information from the surface-based radars. Observations of atmospheric rivers at different locations above the ocean and during landfall help to understand evolutions of atmospheric rivers and their structures.

  8. Empirical Soil Moisture Estimation with Spaceborne L-band Polarimetric Radars: Aquarius, SMAP, and PALSAR-2

    Science.gov (United States)

    Burgin, M. S.; van Zyl, J. J.

    2017-12-01

    Traditionally, substantial ancillary data is needed to parametrize complex electromagnetic models to estimate soil moisture from polarimetric radar data. The Soil Moisture Active Passive (SMAP) baseline radar soil moisture retrieval algorithm uses a data cube approach, where a cube of radar backscatter values is calculated using sophisticated models. In this work, we utilize the empirical approach by Kim and van Zyl (2009) which is an optional SMAP radar soil moisture retrieval algorithm; it expresses radar backscatter of a vegetated scene as a linear function of soil moisture, hence eliminating the need for ancillary data. We use 2.5 years of L-band Aquarius radar and radiometer derived soil moisture data to determine two coefficients of a linear model function on a global scale. These coefficients are used to estimate soil moisture with 2.5 months of L-band SMAP and L-band PALSAR-2 data. The estimated soil moisture is compared with the SMAP Level 2 radiometer-only soil moisture product; the global unbiased RMSE of the SMAP derived soil moisture corresponds to 0.06-0.07 cm3/cm3. In this study, we leverage the three diverse L-band radar data sets to investigate the impact of pixel size and pixel heterogeneity on soil moisture estimation performance. Pixel sizes range from 100 km for Aquarius, over 3, 9, 36 km for SMAP, to 10m for PALSAR-2. Furthermore, we observe seasonal variation in the radar sensitivity to soil moisture which allows the identification and quantification of seasonally changing vegetation. Utilizing this information, we further improve the estimation performance. The research described in this paper is supported by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2017. All rights reserved.

  9. An Improved Semi-Empirical Model for Radar Backscattering from Rough Sea Surfaces at X-Band

    Directory of Open Access Journals (Sweden)

    Taekyeong Jin

    2018-04-01

    Full Text Available We propose an improved semi-empirical scattering model for X-band radar backscattering from rough sea surfaces. This new model has a wider validity range of wind speeds than does the existing semi-empirical sea spectrum (SESS model. First, we retrieved the small-roughness parameters from the sea surfaces, which were numerically generated using the Pierson-Moskowitz spectrum and measurement datasets for various wind speeds. Then, we computed the backscattering coefficients of the small-roughness surfaces for various wind speeds using the integral equation method model. Finally, the large-roughness characteristics were taken into account by integrating the small-roughness backscattering coefficients multiplying them with the surface slope probability density function for all possible surface slopes. The new model includes a wind speed range below 3.46 m/s, which was not covered by the existing SESS model. The accuracy of the new model was verified with two measurement datasets for various wind speeds from 0.5 m/s to 14 m/s.

  10. Electronic structure of the misfit-layer compound (SnS)1.17NbS2 deduced from band-structure calculations and photoelectron spectra

    NARCIS (Netherlands)

    Fang, C.M.; Ettema, A.R.H.F.; Haas, C.; Wiegers, G.A.; Leuken, H. van; Groot, R.A. de

    1995-01-01

    In order to understand the electronic structure of the misfit-layer compound (SnS)1.17NbS2 we carried out an ab initio band-structure calculation of the closely related commensurate compound (SnS)1.20NbS2. The band structure is compared with calculations for NbS2 and for hypothetical SnS with

  11. Understanding the Future Market for NovaSAR-S Flood Mapping Products Using Data Mining and Simulation

    Science.gov (United States)

    Lavender, Samantha; Haria, Kajal; Cooksley, Geraint; Farman, Alex; Beaton, Thomas

    2016-08-01

    The aim was to understand a future market for NovaSAR-S, with a particular focus on flood mapping, through developing a simple Synthetic Aperture Radar (SAR) simulator that can be used in advance of NovaSAR-S data becoming available.The return signal was determined from a combination of a terrain or elevation model, Envisat S-Band Radar Altimeter (RA)-2, Landsat and CORINE land cover information; allowing for a simulation of a SAR image that's influenced by both the geometry and surface type. The test sites correspond to data from the 2014 AirSAR campaign, and validation is performed by using AirSAR together with Envisat Advanced (ASAR) and Advanced Land Observing Satellite "Daichi" (ALOS) Phased Array type L-Band Synthetic Aperture Radar (PALSAR) data.It's envisaged that the resulting simulated data, and the simulator, will not only aid early understanding of NovaSAR-S, but will also aid the development of flood mapping applications.

  12. GPM GROUND VALIDATION MCGILL W-BAND RADAR GCPEX V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation McGill W-Band Radar GCPEx dataset was collected from February 1, 2012 to February 29, 2012 at the CARE site in Ontario, Canada as a part of...

  13. A case study on large-scale dynamical influence on bright band using cloud radar during the Indian summer monsoon

    Science.gov (United States)

    Jha, Ambuj K.; Kalapureddy, M. C. R.; Devisetty, Hari Krishna; Deshpande, Sachin M.; Pandithurai, G.

    2018-02-01

    The present study is a first of its kind attempt in exploring the physical features (e.g., height, width, intensity, duration) of tropical Indian bright band using a Ka-band cloud radar under the influence of large-scale cyclonic circulation and attempts to explain the abrupt changes in bright band features, viz., rise in the bright band height by 430 m and deepening of the bright band by about 300 m observed at around 14:00 UTC on Sep 14, 2016, synoptically as well as locally. The study extends the utility of cloud radar to understand how the bright band features are associated with light precipitation, ranging from 0 to 1.5 mm/h. Our analysis of the precipitation event of Sep 14-15, 2016 shows that the bright band above (below) 3.7 km, thickness less (more) than 300 m can potentially lead to light drizzle of 0-0.25 mm/h (drizzle/light rain) at the surface. It is also seen that the cloud radar may be suitable for bright band study within light drizzle limits than under higher rain conditions. Further, the study illustrates that the bright band features can be determined using the polarimetric capability of the cloud radar. It is shown that an LDR value of - 22 dB can be associated with the top height of bright band in the Ka-band observations which is useful in the extraction of the bright band top height and its width. This study is useful for understanding the bright band phenomenon and could be potentially useful in establishing the bright band-surface rain relationship through the perspective of a cloud radar, which would be helpful to enhance the cloud radar-based quantitative estimates of precipitation.

  14. High resolution emission Fourier transform infrared spectra of the 4p-5s and 5p-6s bands of ArH.

    Science.gov (United States)

    Baskakov, O I; Civis, S; Kawaguchi, K

    2005-03-15

    In the 2500-8500 cm(-1) region several strong emission bands of (40)ArH were observed by Fourier transform spectroscopy through a dc glow discharge in a mixture of argon and hydrogen. Rotational-electronic transitions of the two previously unstudied 4p-5s and 5p-6s,v = 0-0, bands of (40)ArH were measured and assigned in the 6060 and 3770 cm(-1) regions, respectively. A simultaneous fit of the emission transitions of the 4p-5s and 5p-6s bands and an extended set of transitions of the 6s-4p band observed by Dabrowski, Tokaryk, and Watson [J. Mol. Spectrosc. 189, 95 (1998)] and remeasured in the present work yielded consistent values of the spectroscopic parameters of the electronic states under investigation. In the branch of the 4p-5s band with transitions of type (Q)Q(f(3)e) we observed a narrowing in the linewidths with increasing rotational quantum number N. The rotational dependence of the linewidth is caused by predissociation of the 5s state by the repulsive ground 4s state through homogeneous coupling and changes in overlap integrals of the vibrational wave functions with the rotational level. Analysis was based on the Fermi's golden rule approximation model. In the 4p-5s band region a vibrational sequence ofv(')-v(")=1-1, 2-2, and 3-3 were recorded and a number of transitions belonging to the strongest (Q)Q(f(3)e) form branch of the 1-1 band were analyzed.

  15. Spaceborne Applications of P Band Imaging Radars for Measuring Forest Biomass

    Science.gov (United States)

    Rignot, Eric J.; Zimmermann, Reiner; vanZyl, Jakob J.

    1995-01-01

    In three sites of boreal and temperate forests, P band HH, HV, and VV polarization data combined estimate total aboveground dry woody biomass within 12 to 27% of the values derived from allometric equations, depending on forest complexity. Biomass estimates derived from HV-polarization data only are 2 to 14% less accurate. When the radar operates at circular polarization, the errors exceed 100% over flooded forests, wet or damaged trees and sparse open tall forests because double-bounce reflections of the radar signals yield radar signatures similar to that of tall and massive forests. Circular polarizations, which minimize the effect of Faraday rotation in spaceborne applications, are therefore of limited use for measuring forest biomass. In the tropical rain forest of Manu, in Peru, where forest biomass ranges from 4 kg/sq m in young forest succession up to 50 kg/sq m in old, undisturbed floodplain stands, the P band horizontal and vertical polarization data combined separate biomass classes in good agreement with forest inventory estimates. The worldwide need for large scale, updated, biomass estimates, achieved with a uniformly applied method, justifies a more in-depth exploration of multi-polarization long wavelength imaging radar applications for tropical forests inventories.

  16. Band structure and orbital character of monolayer MoS2 with eleven-band tight-binding model

    Science.gov (United States)

    Shahriari, Majid; Ghalambor Dezfuli, Abdolmohammad; Sabaeian, Mohammad

    2018-02-01

    In this paper, based on a tight-binding (TB) model, first we present the calculations of eigenvalues as band structure and then present the eigenvectors as probability amplitude for finding electron in atomic orbitals for monolayer MoS2 in the first Brillouin zone. In these calculations we are considering hopping processes between the nearest-neighbor Mo-S, the next nearest-neighbor in-plan Mo-Mo, and the next nearest-neighbor in-plan and out-of-plan S-S atoms in a three-atom based unit cell of two-dimensional rhombic MoS2. The hopping integrals have been solved in terms of Slater-Koster and crystal field parameters. These parameters are calculated by comparing TB model with the density function theory (DFT) in the high-symmetry k-points (i.e. the K- and Γ-points). In our TB model all the 4d Mo orbitals and the 3p S orbitals are considered and detailed analysis of the orbital character of each energy level at the main high-symmetry points of the Brillouin zone is described. In comparison with DFT calculations, our results of TB model show a very good agreement for bands near the Fermi level. However for other bands which are far from the Fermi level, some discrepancies between our TB model and DFT calculations are observed. Upon the accuracy of Slater-Koster and crystal field parameters, on the contrary of DFT, our model provide enough accuracy to calculate all allowed transitions between energy bands that are very crucial for investigating the linear and nonlinear optical properties of monolayer MoS2.

  17. Challenges with space-time rainfall in urban hydrology highlighted with a semi-distributed model using C-band and X-band radar data

    Science.gov (United States)

    da Silva Rocha Paz, Igor; Ichiba, Abdellah; Skouri-Plakali, Ilektra; Lee, Jisun; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2017-04-01

    Climate change and global warming are expected to make precipitation events more frequent, more severe and more local. This may have serious consequences for human health, the environment, cultural heritage, economic activities, utilities and public service providers. Then precipitation risk and water management is a key challenge for densely populated urban areas. Applications derived from high (time and space) resolution observation of precipitations are to make our cities more weather-ready. Finer resolution data available from X-band dual radar measurements enhance engineering tools as used for urban planning policies as well as protection (mitigation/adaptation) strategies to tackle climate-change related weather events. For decades engineering tools have been developed to work conveniently either with very local rain gauge networks, or with mainly C-band weather radars that have gradually been set up for space-time remote sensing of precipitation. Most of the time, the C-band weather radars continue to be calibrated by the existing rain gauge networks. Inhomogeneous distributions of rain gauging networks lead to only a partial information on the rainfall fields. In fact, the statistics of measured rainfall is strongly biased by the fractality of the measuring networks. This fractality needs to be properly taken in to account to retrieve the original properties of the rainfall fields, in spite of the radar data calibration. In this presentation, with the help of multifractal analysis, we first demonstrate that the semi-distributed hydrological models statistically reduce the rainfall fields into rainfall measured by a much scarcer network of virtual rain gauges. For this purpose, we use C-band and X-band radar data. The first has a resolution of 1 km in space and 5 min in time and is in fact a product provided by RHEA SAS after treating the Météo-France C-band radar data. The latter is measured by the radar operated at Ecole des Ponts and has a resolution of

  18. Política educativa y contingencia: creencias, estatus y confianza detrás del milagro finlandés de PISA

    Directory of Open Access Journals (Sweden)

    Hannu Simola

    2013-01-01

    Full Text Available Los autores sugieren tres conceptos teóricos que consideran prometedores para la educación comparada. Estos son: (1 unificar los conceptos teóricos de dependencia, convergencia y contingencia, (2 trazar la historia de la problemática y (3 analizar las interpretaciones nacionales y locales como híbridos. En su análisis del “milagro finlandés” de PISA, los autores se centran exclusivamente en el concepto de contingencia para ver si se puede facilitar una comprensión más amplia sobre el éxito nacional. Para ello identifican tres ‘verdades’ nacionales que son ampliamente aceptadas en Finlandia a pesar de faltar la evidencia empírica de una investigación que las apoye: los finlandeses comparten una amplia creencia en la escolarización, la enseñanza es una profesión muy apreciada en Finlandia y las escuelas finlandesas gozan de una confianza bastante alta por parte de los padres, las autoridades y los políticos. Este estudio muestra cómo la génesis de estas tres “creencias” nacionales se debe más bien a la casualidad que al resultado de una planificación racional o a un propósito educativo por parte de los políticos. Simola y Rinne concluyen que conceptualizaciones tales como la contingencia, se deben tomar en serio si se persigue una comprensión de las políticas nacionales de educación. El enfoque alternativo, es decir, operar únicamente a través de los modelos funcionalistas y sistemáticos, destacando principalmente las tendencias transnacionales o nacionales, y centrándose exclusivamente en las decisiones y elecciones racionales, no proporciona los instrumentos teóricos adecuados para una investigación comparada.

  19. Identidad mexicana e interés político: Predictores de bienestar social y anomia Identidad mexicana e interés político: Predictores de bienestar social y anomia

    Directory of Open Access Journals (Sweden)

    Claudia Yañez Velasco

    2012-02-01

    Full Text Available This paper tests the hypothesis that perceived differences in Mexican identity and political interest condition social well-being and the perception of anomie. The three dimensions of Tajfel’s social identity theory was adopted to measure Mexican identity, as well as the five dimensions of Keyes’s model for social well-being. A sample of 211 subjects of voting age from the State of Colima, Mexico, filled out a battery of three questionnaires and sociodemographic data. Results show that individuals with a high level of Mexican identity and political interest perceive high levels of social well-being and low level of anomie compared with those who scored low. Correlations were positive for social well-being and negative for anomie, with respect to identity and political interest. The factor of identity affirmation and identification predicted better social integration and actualization, components of social well-being.  Este estudio pone a prueba el supuesto de que las diferencias percibidas en la identidad mexicana y en el interés en la política condicionan la percepción del bienestar social y de la anomia social. Se adoptó la teoría de la identidad social de Tajfel de tres dimensiones para medir la identidad mexicana y el modelo de cinco dimensiones de Keyes para el bienestar social. Una muestra de 211 participantes en edad de votar del estado de Colima, México, contestó una batería de tres cuestionarios y datos sociodemográficos. Los resultados muestran que los individuos con un alto nivel de identidad mexicana y de interés por la política, comparados con los que tienen bajo nivel, perciben mayores niveles de bienestar social y menor nivel de anomia. Las correlaciones de la identidad y el interés por la política fueron positivas para el bienestar social y negativas para la anomia, respectivamente. El factor afirmación e identificación con la identidad predijo mejor la integración y actualización social, componentes del

  20. Rain/snow radar remote sensing with two X-band radars operating over an altitude gradient in the French Alps

    Science.gov (United States)

    Delrieu, Guy; Cazenave, Frédéric; Yu, Nan; Boudevillain, Brice; Faure, Dominique; Gaussiat, Nicolas

    2017-04-01

    Operating weather radars in high-mountain regions faces the following well-known dilemma: (1) installing radar on top of mountains allows for the detection of severe summer convective events over 360° but may give poor QPE performance during a very significant part of the year when the 0°C isotherm is located below or close to the radar altitude; (2) installing radar at lower altitudes may lead to better QPE over sensitive areas such as cities located in valleys, but at the cost of reduced visibility and detection capability in other geographical sectors. We have the opportunity to study this question in detail in the region of Grenoble (an Alpine city of 500 000 inhabitants with an average altitude of 210 m asl) with a pair of X-band polarimetric weather radars operated respectively by Meteo-France on top of Mount Moucherotte (1920 m asl) and by IGE on the Grenoble Campus (213 m asl). The XPORT radar (IGE) performs a combination of PPIs at elevations of 3.5, 7.5, 15 and 25° complemented by two RHIs in the vertical plane passing by the two radar sites, in order to document the 4D precipitation variability within the Grenoble intermountain valley. In the proposed communication, preliminary results of this experiment (started in September 2016) will be presented with highlights on (1) the calibration of the two radar systems, (2) the characterization of the melting layer during significant precipitation events (>5mm/day) occurring in autumn, winter and spring; (3) the simulation of the relative effects of attenuation and non-uniform beam filling at X-band and (4) the possibility to use the mountain returns for quantifying the attenuation by the rain and the melting layer.

  1. Use of the SAR (Synthetic Aperture Radar) P band for detection of the Moche and Lambayeque canal networks in the Apurlec region, Perù

    Science.gov (United States)

    Ilaria Pannaccione Apa, Maria; Santovito, Maria Rosaria; Pica, Giulia; Catapano, Ilaria; Fornaro, Gianfranco; Lanari, Riccardo; Soldovieri, Francesco; Wester La Torre, Carlos; Fernandez Manayalle, Marco Antonio; Longo, Francesco; Facchinetti, Claudia; Formaro, Roberto

    2016-04-01

    In recent years, research attention has been devoted to the development of a new class of airborne radar systems using low frequency bands ranging from VHF/UHF to P and L ones. In this frame, the Italian Space Agency (ASI) has promoted the development of a new multi-mode and multi-band airborne radar system, which can be considered even a "proof-of-concept" for the next space-borne missions. In particular, in agreement with the ASI, the research consortium CO.RI.S.T.A. has in charge the design, development and flight validation of such a kind of system, which is the first airborne radar entirely built in Italy. The aim was to design and realize a radar system able to work in different modalities as: nadir-looking sounder at VHF band (163 MHz); side-looking imager (SAR) at P band with two channels at 450 MHz and 900 MHz. The P-band is a penetration radar. Exploiting penetration features of low frequency electromagnetic waves, dielectric discontinuities of observed scene due to inhomogeneous materials rise up and can be detected on the resulting image. Therefore buried objects or targets placed under vegetation may be detected. Penetration capabilities essentially depend on microwave frequency. Typically, penetration distance is inversely proportional to microwave frequency. The higher the frequency, the lower the penetration depth. Terrain characteristics affect penetration capabilities. Humidity acts as a shield to microwave penetration. Hence terrain with high water content are not good targets for P-band applicability. Science community, governments and space agencies have increased their interest about low frequency radar for their useful applicability in climatology, ecosystem monitoring, glaciology, archaeology. The combination of low frequency and high relative bandwidth of such a systems has a large applicability in both military and civilian applications, ranging from forestry applications, biomass measuring, archaeological and geological exploration

  2. Bunch monitor for an S-band electron linear accelerator

    International Nuclear Information System (INIS)

    Otake, Yuji; Nakahara, Kazuo

    1991-01-01

    The measurement of bunch characteristics in an S-band electron linear accelerator is required in order to evaluate the quality of accelerated electron beams. A new-type bunch monitor has been developed which combines micro-stripline technology with an air insulator and wall-current monitoring technology. The obtained time resolution of the monitor was more than 150 ps. This result shows that the monitor can handle the bunch number of an S-band linac. The structure of the monitor is suitable for being installed in the vacuum area, since it is constructed of only metal and ceramic parts. It can therefore easily be employed in an actual machine

  3. Airborn Ku-band polarimetric radar remote sensing of terrestrial snow cover

    Science.gov (United States)

    Simon H. Yueh; Steve J. Dinardo; Ahmed Akgiray; Richard West; Donald W. Cline; Kelly Elder

    2009-01-01

    Characteristics of the Ku-band polarimetric scatterometer (POLSCAT) data acquired from five sets of aircraft flights in the winter months of 2006-2008 for the second Cold Land Processes Experiment (CLPX-II) in Colorado are described in this paper. The data showed the response of the Ku-band radar echoes to snowpack changes for various types of background vegetation in...

  4. Coupling X-band dual-polarized mini-radars and hydro-meteorological forecast models: the HYDRORAD project

    Directory of Open Access Journals (Sweden)

    E. Picciotti

    2013-05-01

    Full Text Available Hydro-meteorological hazards like convective outbreaks leading to torrential rain and floods are among the most critical environmental issues world-wide. In that context weather radar observations have proven to be very useful in providing information on the spatial distribution of rainfall that can support early warning of floods. However, quantitative precipitation estimation by radar is subjected to many limitations and uncertainties. The use of dual-polarization at high frequency (i.e. X-band has proven particularly useful for mitigating some of the limitation of operational systems, by exploiting the benefit of easiness to transport and deploy and the high spatial and temporal resolution achievable at small antenna sizes. New developments on X-band dual-polarization technology in recent years have received the interest of scientific and operational communities in these systems. New enterprises are focusing on the advancement of cost-efficient mini-radar network technology, based on high-frequency (mainly X-band and low-power weather radar systems for weather monitoring and hydro-meteorological forecasting. Within the above context, the main objective of the HYDRORAD project was the development of an innovative mbox{integrated} decision support tool for weather monitoring and hydro-meteorological applications. The integrated system tool is based on a polarimetric X-band mini-radar network which is the core of the decision support tool, a novel radar products generator and a hydro-meteorological forecast modelling system that ingests mini-radar rainfall products to forecast precipitation and floods. The radar products generator includes algorithms for attenuation correction, hydrometeor classification, a vertical profile reflectivity correction, a new polarimetric rainfall estimators developed for mini-radar observations, and short-term nowcasting of convective cells. The hydro-meteorological modelling system includes the Mesoscale Model 5

  5. Enhance the accuracy of radar snowfall estimation with Multi new Z-S relationships in MRMS system

    Science.gov (United States)

    Qi, Y.

    2017-12-01

    Snow may have negative affects on roadways and human lives, but the result of the melted snow/ice is good for farm, humans, and animals. For example, in the Southwest and West mountainous area of United States, water shortage is a very big concern. However, snowfall in the winter can provide humans, animals and crops an almost unlimited water supply. So, using radar to accurately estimate the snowfall is very important for human life and economic development in the water lacking area. The current study plans to analyze the characteristics of the horizontal and vertical variations of dry/wet snow using dual polarimetric radar observations, relative humidity and in situ snow water equivalent observations from the National Weather Service All Weather Prediction Accumulation Gauges (AWPAG) across the CONUS, and establish the relationships between the reflectivity (Z) and ground snow water equivalent (S). The new Z-S relationships will be evaluated with independent CoCoRaHS (Community Collaborative Rain, Hail & Snow Network) gauge observations and eventually implemented in the Multi-Radar Multi-Sensor system for improved quantitative precipitation estimation for snow. This study will analyze the characteristics of the horizontal and vertical variations of dry/wet snow using dual polarimetric radar observations, relative humidity and in situ snow water equivalent observations from the National Weather Service All Weather Prediction Accumulation Gauges (AWPAG) across the CONUS, and establish the relationships between the reflectivity (Z) and ground snow water equivalent (S). The new Z-S relationships will be used to reduce the error of snowfall estimation in Multi Radar and Multi Sensors (MRMS) system, and tested in MRMS system and evaluated with the COCORaHS observations. Finally, it will be ingested in MRMS sytem, and running in NWS/NCAR operationally

  6. Edad, cohortes o período. Desenredando las causas del desinterés político en España

    Directory of Open Access Journals (Sweden)

    Carolina Galais

    2012-01-01

    Full Text Available ¿En qué medida el escaso interés por la política de los españoles se debe al efecto de la edad, del período o de la pertenencia a una cohorte? Mientras que la edad no puede explicar la evolución de los niveles agregados de interés por la política a lo largo del tiempo, la sustitución generacional sí; aunque cabe determinar si su efecto aumentaría, reproduciría o empeoraría los actuales niveles interés político. Finalmente, cabe tener en cuenta el período, el único factor capaz de provocar cambios a corto plazo en esta actitud. El artículo también pretende arrojar algo de luz sobre los mecanismos por los cuales determinadas cohortes tendrían una mayor o menor propensión a interesarse por la política; y concluye que el grado de desarrollo social y económico que experimentaron mientras crecieron resulta crucial.

  7. Atmospheric and Fog Effects on Ultra-Wide Band Radar Operating at Extremely High Frequencies.

    Science.gov (United States)

    Balal, Nezah; Pinhasi, Gad A; Pinhasi, Yosef

    2016-05-23

    The wide band at extremely high frequencies (EHF) above 30 GHz is applicable for high resolution directive radars, resolving the lack of free frequency bands within the lower part of the electromagnetic spectrum. Utilization of ultra-wideband signals in this EHF band is of interest, since it covers a relatively large spectrum, which is free of users, resulting in better resolution in both the longitudinal and transverse dimensions. Noting that frequencies in the millimeter band are subjected to high atmospheric attenuation and dispersion effects, a study of the degradation in the accuracy and resolution is presented. The fact that solid-state millimeter and sub-millimeter radiation sources are producing low power, the method of continuous-wave wideband frequency modulation becomes the natural technique for remote sensing and detection. Millimeter wave radars are used as complementary sensors for the detection of small radar cross-section objects under bad weather conditions, when small objects cannot be seen by optical cameras and infrared detectors. Theoretical analysis for the propagation of a wide "chirped" Frequency-Modulated Continuous-Wave (FMCW) radar signal in a dielectric medium is presented. It is shown that the frequency-dependent (complex) refractivity of the atmospheric medium causes distortions in the phase of the reflected signal, introducing noticeable errors in the longitudinal distance estimations, and at some frequencies may also degrade the resolution.

  8. Determination of band offsets at GaN/single-layer MoS2 heterojunction

    KAUST Repository

    Tangi, Malleswararao

    2016-07-25

    We report the band alignment parameters of the GaN/single-layer (SL) MoS2 heterostructure where the GaN thin layer is grown by molecular beam epitaxy on CVD deposited SL-MoS2/c-sapphire. We confirm that the MoS2 is an SL by measuring the separation and position of room temperature micro-Raman E1 2g and A1 g modes, absorbance, and micro-photoluminescence bandgap studies. This is in good agreement with HRTEM cross-sectional analysis. The determination of band offset parameters at the GaN/SL-MoS2 heterojunction is carried out by high-resolution X-ray photoelectron spectroscopy accompanying with electronic bandgap values of SL-MoS2 and GaN. The valence band and conduction band offset values are, respectively, measured to be 1.86 ± 0.08 and 0.56 ± 0.1 eV with type II band alignment. The determination of these unprecedented band offset parameters opens up a way to integrate 3D group III nitride materials with 2D transition metal dichalcogenide layers for designing and modeling of their heterojunction based electronic and photonic devices.

  9. Determination of band offsets at GaN/single-layer MoS2 heterojunction

    KAUST Repository

    Tangi, Malleswararao; Mishra, Pawan; Ng, Tien Khee; Hedhili, Mohamed N.; Janjua, Bilal; Alias, Mohd Sharizal; Anjum, Dalaver H.; Tseng, Chien-Chih; Shi, Yumeng; Joyce, Hannah J.; Li, Lain-Jong; Ooi, Boon S.

    2016-01-01

    We report the band alignment parameters of the GaN/single-layer (SL) MoS2 heterostructure where the GaN thin layer is grown by molecular beam epitaxy on CVD deposited SL-MoS2/c-sapphire. We confirm that the MoS2 is an SL by measuring the separation and position of room temperature micro-Raman E1 2g and A1 g modes, absorbance, and micro-photoluminescence bandgap studies. This is in good agreement with HRTEM cross-sectional analysis. The determination of band offset parameters at the GaN/SL-MoS2 heterojunction is carried out by high-resolution X-ray photoelectron spectroscopy accompanying with electronic bandgap values of SL-MoS2 and GaN. The valence band and conduction band offset values are, respectively, measured to be 1.86 ± 0.08 and 0.56 ± 0.1 eV with type II band alignment. The determination of these unprecedented band offset parameters opens up a way to integrate 3D group III nitride materials with 2D transition metal dichalcogenide layers for designing and modeling of their heterojunction based electronic and photonic devices.

  10. Teresa Andrés Zamora (1907-1946: el compromiso social y político como arma de cultura

    Directory of Open Access Journals (Sweden)

    Seguí i Francés, Romà

    2010-12-01

    Full Text Available La biografía de Teresa Andrés Zamora (Villalba de los Alcores, 1907- París, 1946 es un claro ejemplo de cómo el compromiso de una mujer republicana a través de la cultura se transformó en beligerancia política. Este artículo quiere mostrar una imagen de Teresa Andréss profunda que la de una bibliotecaria que militó en el PCE, pretendiendo reconstruir su recorrido vital tanto en la faceta académica como profesional y política, con el objetivo de presentar una evolución que va desde su paso por la Residencia de Señoritas hasta su prematura muerte en París. Teresa Andrés Zamora representa una generación de mujeres republicanas que fue leal a la II República, trabajando incansablemente durante la Guerra Civil, y que padeció el exilio en una Francia ocupada.

  11. Arabidopsis Pol II-Dependent in Vitro Transcription System Reveals Role of Chromatin for Light-Inducible rbcS Gene Transcription1

    Science.gov (United States)

    Ido, Ayaka; Iwata, Shinya; Iwata, Yuka; Igarashi, Hisako; Hamada, Takahiro; Sonobe, Seiji; Sugiura, Masahiro; Yukawa, Yasushi

    2016-01-01

    In vitro transcription is an essential tool to study the molecular mechanisms of transcription. For over a decade, we have developed an in vitro transcription system from tobacco (Nicotiana tabacum)-cultured cells (BY-2), and this system supported the basic activities of the three RNA polymerases (Pol I, Pol II, and Pol III). However, it was not suitable to study photosynthetic genes, because BY-2 cells have lost their photosynthetic activity. Therefore, Arabidopsis (Arabidopsis thaliana) in vitro transcription systems were developed from green and etiolated suspension cells. Sufficient in vitro Pol II activity was detected after the minor modification of the nuclear soluble extracts preparation method; removal of vacuoles from protoplasts and L-ascorbic acid supplementation in the extraction buffer were particularly effective. Surprisingly, all four Arabidopsis Rubisco small subunit (rbcS-1A, rbcS-1B, rbcS-2B, and rbcS-3B) gene members were in vitro transcribed from the naked DNA templates without any light-dependent manner. However, clear light-inducible transcriptions were observed using chromatin template of rbcS-1A gene, which was prepared with a human nucleosome assembly protein 1 (hNAP1) and HeLa histones. This suggested that a key determinant of light-dependency through the rbcS gene transcription was a higher order of DNA structure (i.e. chromatin). PMID:26662274

  12. Spectral Polarimetric Features Analysis of Wind Turbine Clutter in Weather Radar

    NARCIS (Netherlands)

    Yin, J.; Krasnov, O.A.; Unal, C.M.H.; Medagli, S.; Russchenberg, H.W.J.

    2017-01-01

    Wind turbine clutter has gradually become a concern for the radar community for its increasing size and quantity worldwide. Based on the S-band polarimetric Doppler PARSAX radar measurements, this paper demonstrates the micro-Doppler features and spectral-polarimetric characteristic of wind turbine

  13. A simple device for long-term radar cross section recordings.

    Science.gov (United States)

    Eskelinen, Pekka; Ruoskanen, Jukka; Peltonen, Jouni

    2009-05-01

    A sample and hold circuit with settable delay can be used for recording of radar echo amplitude variations having time scales up to 100 s at the selected range bin in systems utilizing short rf pulses. The design is based on two integrated circuits and gives 1% uncertainty for 70 ns pulses. The key benefit is a real-time display of lengthy amplitude variations because the sample rate is defined by the radar pulse repetition frequency. Additionally we get a reduction in file size at least by the inverse of the radar's duty cycle. Examples of 10 and 100 s recordings with a Ka-band short pulse radar are described.

  14. O Mercosul na política de integração de Venezuela = Mercosur in Venezuela’s integration policy

    Directory of Open Access Journals (Sweden)

    Briceño-Ruiz, José

    2010-01-01

    Full Text Available Neste artigo argumenta-se que a estratégia do governo Chávez de solicitar a adesão ao Mercosul deve ser contextualizada no quadro das mudanças políticas internas na Venezuela e da forma como estas mudanças tem influído na elaboração e aplicação de política externa deste país. Neste sentido, qualquer decisão do governo venezuelano em matéria de integração regional está subordinada à consecução dos três objetivos básicos da política exterior do país: a luta contra a ordem unipolar, transformada nos anos recentes em anti-imperialismo; a rejeição ao neoliberalismo, que se converteu em anticapitalismo e a promoção da integração bolivariana. A dificuldade de compatibilizar os objetivos da política exterior venezuelana com a realidade política, estratégica e regulamento institucional do Mercosul e os custos econômicos que teria para o país adotar o programa de liberalização do Protocolo de Caracas explicam as dificuldades da adesão venezuelana ao Mercosul

  15. Plans for the Meter Class Autonomous Telescope and Potential Coordinated Measurements with Kwajalein Radars

    Science.gov (United States)

    Stansberry, Gene; Kervin, Paul; Mulrooney, Mark

    2010-01-01

    The National Aeronautics and Space Administration's (NASA) Orbital Debris Program Office is teaming with the US Air Force Research Laboratory's (AFRL) Maui Optical Site to deploy a moderate field-of-view, 1.3 m aperture, optical telescope for orbital debris applications. The telescope will be located on the island of Legan in the Kwajalein Atoll and is scheduled for completion in the Spring of 2011. The telescope is intended to sample both low inclination/high eccentricity orbits and near geosynchronous orbits. The telescope will have a 1 deg diagonal field-of-view on a 4K x 4K CCD. The telescope is expected to be able to detect 10-cm diameter debris at geosynchronous altitudes (5 sec exposure assuming a spherical specular phase function w/ albedo =0.13). Once operational, the telescope has the potential of conducting simultaneous observations with radars operated by the US Army at Kwajalein Atoll (USAKA) and located on the island of Roi-Namur, approximately 55 km to the north of Legan. Four radars, representing 6 frequency bands, are available for use: ALTAIR (ARPA-Long Range Tracking and Instrumentation Radar) operating at VHF & UHF, TRADEX (Target Resolution and Discrimination Experiment) operating at L-band and S-band, ALCOR (ARPA-Lincoln C-band Observables Radar) operating at S-band, and MMW (Millimeter Wave) Radar operating at Ka-band. Also potentially available is the X-band GBRP (Ground Based Radar-Prototype located 25 km to the southeast of Legan on the main island of Kwajalein.

  16. The NASA Polarimetric Radar (NPOL)

    Science.gov (United States)

    Petersen, Walter A.; Wolff, David B.

    2013-01-01

    Characteristics of the NASA NPOL S-band dual-polarimetric radar are presented including its operating characteristics, field configuration, scanning capabilities and calibration approaches. Examples of precipitation science data collections conducted using various scan types, and associated products, are presented for different convective system types and previous field campaign deployments. Finally, the NASA NPOL radar location is depicted in its home base configuration within the greater Wallops Flight Facility precipitation research array supporting NASA Global Precipitation Measurement Mission ground validation.

  17. Comparing and Merging Observation Data from Ka-Band Cloud Radar, C-Band Frequency-Modulated Continuous Wave Radar and Ceilometer Systems

    Directory of Open Access Journals (Sweden)

    Liping Liu

    2017-12-01

    Full Text Available Field experiment in South China was undertaken to improve understanding of cloud and precipitation properties. Measurements of the vertical structures of non-precipitating and precipitating clouds were obtained using passive and active remote sensing equipment: a Ka-band cloud radar (CR system, a C-band frequency modulated continuous wave vertical pointing radar (CVPR, a microwave radiometer and a laser ceilometer (CEIL. CR plays a key role in high-level cloud observation, whereas CVPR is important for observing low- and mid-level clouds and heavy precipitation. CEIL helps us diminish the effects of “clear-sky” in the planetary boundary layer. The experiment took place in Longmen, Guangdong Province, China from May to September of 2016. This study focuses on evaluating the ability of the two radars to deliver consistent observation data and develops an algorithm to merge the CR, CVPR and CEIL data. Cloud echo base, thickness, frequency of observed cloud types and reflectivity vertical distributions are analyzed in the radar data. Comparisons between the collocated data sets show that reflectivity biases between the CR three operating modes are less than 2 dB. The averaged difference between CR and CVPR reflectivity can be reduced with attenuation correction to 3.57 dB from the original 4.82 dB. No systemic biases were observed between velocity data collected in the three CR modes and CVPR. The corrected CR reflectivity and velocity data were then merged with the CVPR data and CEIL data to fill in the gaps during the heavy precipitation periods and reduce the effects of Bragg scattering and fog on cloud observations in the boundary layer. Meanwhile, the merging of velocity data with different Nyquist velocities and resolutions diminishes velocity folding to provide fine-grain information about cloud and precipitation dynamics. The three daily periods in which low-level clouds tended to occur were at sunrise, noon and sunset and large

  18. Religião e política: o pensamento antimaquiavelista espanhol dos séculos XVI E XVII

    Directory of Open Access Journals (Sweden)

    Jaime Estevão dos Reis

    2013-09-01

    Full Text Available Este artigo tem como objetivo discutir a relação entre religião e política no pensamento antimaquiavelista espanhol de fins do século XVI e primeira metade do século XVII. Frente à razão de Estado defendida por Nicolau Maquiavel, que qualificam como errônea e falsa, os escritores políticos espanhóis propõem o que chamam de verdadeira razão de Estado, baseada em princípios cristãos.

  19. Temporal Decorrelation Effect in Carbon Stocks Estimation Using Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR (Case Study: Southeast Sulawesi Tropical Forest

    Directory of Open Access Journals (Sweden)

    Laode M Golok Jaya

    2017-07-01

    Full Text Available This paper was aimed to analyse the effect of temporal decorrelation in carbon stocks estimation. Estimation of carbon stocks plays important roles particularly to understand the global carbon cycle in the atmosphere regarding with climate change mitigation effort. PolInSAR technique combines the advantages of Polarimetric Synthetic Aperture Radar (PolSAR and Interferometry Synthetic Aperture Radar (InSAR technique, which is evidenced to have significant contribution in radar mapping technology in the last few years. In carbon stocks estimation, PolInSAR provides information about vertical vegetation structure to estimate carbon stocks in the forest layers. Two coherence Synthetic Aperture Radar (SAR images of ALOS PALSAR full-polarimetric with 46 days temporal baseline were used in this research. The study was carried out in Southeast Sulawesi tropical forest. The research method was by comparing three interferometric phase coherence images affected by temporal decorrelation and their impacts on Random Volume over Ground (RvoG model. This research showed that 46 days temporal baseline has a significant impact to estimate tree heights of the forest cover where the accuracy decrease from R2=0.7525 (standard deviation of tree heights is 2.75 meters to R2=0.4435 (standard deviation 4.68 meters and R2=0.3772 (standard deviation 3.15 meters respectively. However, coherence optimisation can provide the best coherence image to produce a good accuracy of carbon stocks.

  20. Stimulation of Pol III-dependent 5S rRNA and U6 snRNA gene expression by AP-1 transcription factors.

    Science.gov (United States)

    Ahuja, Richa; Kumar, Vijay

    2017-07-01

    RNA polymerase III transcribes structurally diverse group of essential noncoding RNAs including 5S ribosomal RNA (5SrRNA) and U6 snRNA. These noncoding RNAs are involved in RNA processing and ribosome biogenesis, thus, coupling Pol III activity to the rate of protein synthesis, cell growth, and proliferation. Even though a few Pol II-associated transcription factors have been reported to participate in Pol III-dependent transcription, its activation by activator protein 1 (AP-1) factors, c-Fos and c-Jun, has remained unexplored. Here, we show that c-Fos and c-Jun bind to specific sites in the regulatory regions of 5S rRNA (type I) and U6 snRNA (type III) gene promoters and stimulate their transcription. Our chromatin immunoprecipitation studies suggested that endogenous AP-1 factors bind to their cognate promoter elements during the G1/S transition of cell cycle apparently synchronous with Pol III transcriptional activity. Furthermore, the interaction of c-Jun with histone acetyltransferase p300 promoted the recruitment of p300/CBP complex on the promoters and facilitated the occupancy of Pol III transcriptional machinery via histone acetylation and chromatin remodeling. The findings of our study, together, suggest that AP-1 factors are novel regulators of Pol III-driven 5S rRNA and U6 snRNA expression with a potential role in cell proliferation. © 2017 Federation of European Biochemical Societies.

  1. ANALYSIS OF DEBRIS FLOW DISASTER DUE TO HEAVY RAIN BY X-BAND MP RADAR DATA

    Directory of Open Access Journals (Sweden)

    M. Nishio

    2016-06-01

    Full Text Available On August 20 of 2014, Hiroshima City (Japan was struck by local heavy rain from an autumnal rain front. The resultant debris flow disaster claimed 75 victims and destroyed many buildings. From 1:30 am to 4:30 am on August 20, the accumulated rainfall in Hiroshima City exceeded 200 mm. Serious damage occurred in the Asakita and Asaminami wards of Hiroshima City. As a disaster prevention measure, local heavy rain (localized torrential rains is usually observed by the Automated Meteorological Data Acquisition System (AMeDAS operated by the Japan Meteorological Agency (JMA and by the C-band radar operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT of Japan, with spatial resolutions of 2.5 km and 1 km, respectively. The new X-band MP radar system enables more detailed rainfall observations than the C-band radar. In fact, this radar can observe local rainfall throughout Japan in near-real time over a minimum mesh size of 250 m. A fine-scale accumulated rainfall monitoring system is crucial for disaster prevention, and potential disasters can be alerted by the hazard levels of the accumulated rainfall.

  2. Analysis of high resolution land clutter using an X-band radar

    CSIR Research Space (South Africa)

    Melebari, A

    2015-10-01

    Full Text Available . Measurements were performed with an X-band radar system with two instantaneous bandwidths of 40 MHz and 400 MHz. The clutter data was analyzed by fitting the amplitude Probability Distribution Function (PDF) to different distributions using the Method...

  3. Pasiones políticas e imperialismo : la polémica entre Ginés de Sepúlveda y Bartolomé de las Casas

    Directory of Open Access Journals (Sweden)

    Sandra Chaparro

    2001-01-01

    Full Text Available Durante siglos el «amor» se ha venido considerando una virtud política, sostenedora de la vida comunitaria y fuente de la solidaridad social. Como tal, se trata de una pasión que se encuentra en la base de los sistemas simbólicos del pensamiento político occidental, si bien hoy, pasiones y política parecen dos conceptos alejados entre sí No obstante, en un mundo en vías de globalización resurgen con fuerza términos como solidaridad o cooperación, conceptos que implican una buena dosis de «amor político». El objeto de este trabajo es recurrir al ejemplo histórico como una buena manera de señalar los riesgos y limitaciones de esta estrategia. Así, en él se analizan los debates suscitados en el siglo xvi en torno a la forma correcta de cristianizar a las sociedades indígenas americanas a través de la polémica entre el «universalismo benevolente» de Bartolomé de las Casas y la idea de «cruzada como acto de amor» de Ginés de Sepúlveda. Esta polémica histórica resulta ser un magnifico ejemplo de la disputa en torno a la correcta utilización de las «pasiones políticas».For centuries, «love» as been a political virtue enhancing communitarism and social solidarity. As such, it as been a passion we find in the basis of the symbolic systems of wesern political thought, though nowadays passions and politics seem to be different realities. Nevertheless, in a worid in which globalization process take place, concepts based on «political love» like solidarity or cooperation recover their original force. The aim of this study is to appeal to an historical example to show the risks and limits of certain kinds of globalization strategies. This article is about the debates that took place in the sixteenth century, when jurists and theologians had to decide which was the right way of christianizing american natives. The historical debate between Bartolomé dse las Casas and his concept of «benevolent universalism» and Gines

  4. A dimensão político-institucional das estratégias sócio ambientais: o jogo Aracruz Celulose S.A. - índios Tupiniquim e Guarani

    Directory of Open Access Journals (Sweden)

    Andrade José Célio Silveira

    2001-01-01

    Full Text Available Analisando o jogo de conflito e cooperação entre a Aracruz Celulose e os Índios Tupiniquim e Guarani, este trabalho alerta para a necessidade de estudar o processo de formação das estratégias sócio-ambientais como um exercício político de busca de legitimidade. Neste sentido, os autores analisam a dimensão político-institucional das estratégias sócio-ambientais da Aracruz Celulose, a partir de um referencial teórico baseado na abordagem sociológica das lógicas de ação dos atores organizacionais.

  5. CPM Signals for Satellite Navigation in the S and C Bands.

    Science.gov (United States)

    Xue, Rui; Sun, Yanbo; Zhao, Danfeng

    2015-06-05

    Frequency allocations in the L band suitable for global navigation satellite system (GNSS) services are getting crowded and system providers face an ever tougher job when they try to bring in new signals and services while maintaining radio frequency compatibility. With the successive opening of the S and C bands to GNSS service, the multi-band combined navigation is predicted to become a key technology for future high-precision positioning navigation systems, and a single modulation scheme satisfying the requirements in each band is a promising solution for reducing user terminal complexity. A universal modulation scheme based on the continuous phase modulation (CPM) family suitable for the above bands' demands is proposed. Moreover, this paper has put forward two specific CPM signals for the S and C bands, respectively. Then the proposed modulation schemes, together with existing candidates, are comprehensively evaluated. Simulation results show that the proposed CPM signals can not only satisfy the constraint condition of compatibility in different bands well and reduce user terminal complexity, but also provide superior performance in terms of tracking accuracy, multi-path mitigation and anti-jamming compared to other candidate modulation schemes.

  6. S-band 45 MW peak power test facility at RRCAT

    International Nuclear Information System (INIS)

    Wanmode, A. Yashwant; Reddy, Sivananda; Mulchandani, J.; Mohania, Praveen; Shrivastava, B. Purushottam

    2015-01-01

    RRCAT is engaged in the design and development of high energy electron LINAC as future injectors for the Booster Synchrotron for Indus-1 and Indus-2 SRS. The high energy LINAC will need microwave power over 30 MW depending on the number of structures to be energized. In order to have advance preparations for this development a 45 MW S-Band test facility has been designed and developed at RRCAT. The test stand is built around a 45 MW peak power S-band pulsed klystron, A conventional pulse forming network based modulator for klystron has been designed and developed. The WR-284 waveguide transmission system consisting of dual directional couplers, SF 6 gas pressurization unit, high power waveguide load and arc sensor has been developed and interfaced with the klystron. The klystron has been successfully tested up to 30 MW peak power at 2856 MHz on SF 6 pressurized waveguide line. A solid state S Band driver amplifier up to 1 kW output power was designed developed for driving the klystron. This paper describes the results of 30 MW peak power test of this facility. (author)

  7. Band gap engineering of MoS{sub 2} upon compression

    Energy Technology Data Exchange (ETDEWEB)

    López-Suárez, Miquel, E-mail: miquel.lopez@nipslab.org [NiPS Laboratory, Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia (Italy); Neri, Igor [NiPS Laboratory, Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia (Italy); INFN Sezione di Perugia, via Pascoli, 06123 Perugia (Italy); Rurali, Riccardo [Institut de Ciència de Materials de Barcelona (ICMAB–CSIC) Campus de Bellaterra, 08193 Bellaterra, Barcelona (Spain)

    2016-04-28

    Molybdenum disulfide (MoS{sub 2}) is a promising candidate for 2D nanoelectronic devices, which shows a direct band-gap for monolayer structure. In this work we study the electronic structure of MoS{sub 2} upon both compressive and tensile strains with first-principles density-functional calculations for different number of layers. The results show that the band-gap can be engineered for experimentally attainable strains (i.e., ±0.15). However, compressive strain can result in bucking that can prevent the use of large compressive strain. We then studied the stability of the compression, calculating the critical strain that results in the on-set of buckling for free-standing nanoribbons of different lengths. The results demonstrate that short structures, or few-layer MoS{sub 2}, show semi-conductor to metal transition upon compressive strain without bucking.

  8. Observations of a Cold Front at High Spatiotemporal Resolution Using an X-Band Phased Array Imaging Radar

    Directory of Open Access Journals (Sweden)

    Andrew Mahre

    2017-02-01

    Full Text Available While the vertical structure of cold fronts has been studied using various methods, previous research has shown that traditional methods of observing meteorological phenomena (such as pencil-beam radars in PPI/volumetric mode are not well-suited for resolving small-scale cold front phenomena, due to relatively low spatiotemporal resolution. Additionally, non-simultaneous elevation sampling within a vertical cross-section can lead to errors in analysis, as differential vertical advection cannot be distinguished from temporal evolution. In this study, a cold front from 19 September 2015 is analyzed using the Atmospheric Imaging Radar (AIR. The AIR transmits a 20-degree fan beam in elevation, and digital beamforming is used on receive to generate simultaneous receive beams. This mobile, X-band, phased-array radar offers temporal sampling on the order of 1 s (while in RHI mode, range sampling of 30 m (37.5 m native resolution, and continuous, arbitrarily oversampled data in the vertical dimension. Here, 0.5-degree sampling is used in elevation (1-degree native resolution. This study is the first in which a cold front has been studied via imaging radar. The ability of the AIR to obtain simultaneous RHIs at high temporal sampling rates without mechanical steering allows for analysis of features such as Kelvin-Helmholtz instabilities and feeder flow.

  9. High Peak Power Test and Evaluation of S-band Waveguide Switches

    Science.gov (United States)

    Nassiri, A.; Grelick, A.; Kustom, R. L.; White, M.

    1997-05-01

    The injector and source of particles for the Advanced Photon Source is a 2856-MHz S-band electron-positron linear accelerator (linac) which produces electrons with energies up to 650 MeV or positrons with energies up to 450 MeV. To improve the linac rf system availability, an additional modulator-klystron subsystem is being constructed to provide a switchable hot spare unit for each of the five exsisting S-band transmitters. The switching of the transmitters will require the use of SF6-pressurized S-band waveguide switches at a peak operating power of 35 MW. Such rf switches have been successfully operated at other accelerator facilities but at lower peak powers. A test stand has been set up at the Stanford Linear Accelerator Center (SLAC) Klystron Factory to conduct tests comparing the power handling characteristics of two WR-284 and one WR-340 switches. Test results are presented and their implications for the design of the switching system are discussed.

  10. Radar search and detection with the CASA 212 S43 aircraft

    OpenAIRE

    Landa Borges, José Manuel

    2004-01-01

    Approved for public release; distribution in unlimited. This research develops a detection rate model to analyze the effectiveness of the RDR 1500B search radar installed in the CASA 212 S43 aircraft belonging to Venezuelan Naval Aviation. The model is based on a search and detection mission to find a diesel submarine executing an incursion inside the Venezuelan Caribbean Sea area, assumed to be intermittently operating with periscopes or masts exposed above the sea surface. The analysis o...

  11. Systèmes de type radar appliqués aux domaines routiers et ferroviaires

    OpenAIRE

    DELOOF, P; GHYS, JP; RIVENQ, A; HAESE, N; SAINT-VENANT, M

    2001-01-01

    La détection d'obstacles par radar peut s'appliquer aussi bien au domaine des transports routiers qu'à ceux des transports en commun. Quelques uns de ces systèmes sont étudiés au LEOST dans le cadre du GRRT, Groupement Régional Nord Pas-de-Calais pour la Recherche dans les Transports. La plupart des capteurs micro-ondes furent réalisés par le DHS. Ils étaient fondés soit sur la modulation linéaire en fréquence (FMCW) soit sur la modulation par impulsions. Ces études ont mené à la réalisation ...

  12. Determination of band offsets at GaN/single-layer MoS{sub 2} heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Tangi, Malleswararao; Mishra, Pawan; Ng, Tien Khee; Janjua, Bilal; Alias, Mohd Sharizal; Ooi, Boon S., E-mail: boon.ooi@kaust.edu.sa [Photonics Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Hedhili, Mohamed Nejib; Anjum, Dalaver H. [Adavanced Nanofabrication Imaging and Characterization, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Tseng, Chien-Chih; Shi, Yumeng; Li, Lain-Jong [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Joyce, Hannah J. [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, Cambridgeshire CB3 0FA (United Kingdom)

    2016-07-18

    We report the band alignment parameters of the GaN/single-layer (SL) MoS{sub 2} heterostructure where the GaN thin layer is grown by molecular beam epitaxy on CVD deposited SL-MoS{sub 2}/c-sapphire. We confirm that the MoS{sub 2} is an SL by measuring the separation and position of room temperature micro-Raman E{sup 1}{sub 2g} and A{sup 1}{sub g} modes, absorbance, and micro-photoluminescence bandgap studies. This is in good agreement with HRTEM cross-sectional analysis. The determination of band offset parameters at the GaN/SL-MoS{sub 2} heterojunction is carried out by high-resolution X-ray photoelectron spectroscopy accompanying with electronic bandgap values of SL-MoS{sub 2} and GaN. The valence band and conduction band offset values are, respectively, measured to be 1.86 ± 0.08 and 0.56 ± 0.1 eV with type II band alignment. The determination of these unprecedented band offset parameters opens up a way to integrate 3D group III nitride materials with 2D transition metal dichalcogenide layers for designing and modeling of their heterojunction based electronic and photonic devices.

  13. Ground and Space Radar Volume Matching and Comparison Software

    Science.gov (United States)

    Morris, Kenneth; Schwaller, Mathew

    2010-01-01

    This software enables easy comparison of ground- and space-based radar observations. The software was initially designed to compare ground radar reflectivity from operational, ground based Sand C-band meteorological radars with comparable measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite s Precipitation Radar (PR) instrument. The software is also applicable to other ground-based and space-based radars. The ground and space radar volume matching and comparison software was developed in response to requirements defined by the Ground Validation System (GVS) of Goddard s Global Precipitation Mission (GPM) project. This software innovation is specifically concerned with simplifying the comparison of ground- and spacebased radar measurements for the purpose of GPM algorithm and data product validation. This software is unique in that it provides an operational environment to routinely create comparison products, and uses a direct geometric approach to derive common volumes of space- and ground-based radar data. In this approach, spatially coincident volumes are defined by the intersection of individual space-based Precipitation Radar rays with the each of the conical elevation sweeps of the ground radar. Thus, the resampled volume elements of the space and ground radar reflectivity can be directly compared to one another.

  14. Design of an S band narrow-band bandpass BAW filter

    Science.gov (United States)

    Gao, Yang; Zhao, Kun-li; Han, Chao

    2017-11-01

    An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss - 1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designed for potential UAV measurement and control applications. According to the design specifications, the design is as follows: each FBAR's stack was designed in BAW filter by using Mason model. Each FBAR's shape was designed with the method of apodization electrode. The layout of BAW filter was designed. The acoustic-electromagnetic cosimulation model was built to validate the performance of the designed BAW filter. The presented design procedure is a common one, and there are two characteristics: 1) an A and EM co-simulation method is used for the final BAW filter performance validation in the design stage, thus ensures over-optimistic designs by the bare 1D Mason model are found and rejected in time; 2) An in-house developed auto-layout method is used to get compact BAW filter layout, which simplifies iterative error-and-try work here and output necessary in-plane geometry information to the A and EM cosimulation model.

  15. Detection of hail through the three-body scattering signatures and its effects on radar algorithms observed in Romania

    OpenAIRE

    CARBUNARU, DANIEL VICTOR; SASU, MONICA; BURCEA, SORIN; BELL, AURORA

    2014-01-01

    The Romanian National Meteorological Administration (NMA) radar network consists of five S-band and four C-band radars. Observation of convection in Romania through the Doppler radar network offered a new perspective in understanding the climatologic risk of certain regions and mesoscale environments. Highly organized convective systems, such as supercells, are better observed and their subsequent threat can be better anticipated during the nowcasting process using Doppler velocity fields and...

  16. The SOS and RpoS Regulons Contribute to Bacterial Cell Robustness to Genotoxic Stress by Synergistically Regulating DNA Polymerase Pol II.

    Science.gov (United States)

    Dapa, Tanja; Fleurier, Sébastien; Bredeche, Marie-Florence; Matic, Ivan

    2017-07-01

    Mitomycin C (MMC) is a genotoxic agent that induces DNA cross-links, DNA alkylation, and the production of reactive oxygen species (ROS). MMC induces the SOS response and RpoS regulons in Escherichia coli SOS-encoded functions are required for DNA repair, whereas the RpoS regulon is typically induced by metabolic stresses that slow growth. Thus, induction of the RpoS regulon by MMC may be coincidental, because DNA damage slows growth; alternatively, the RpoS regulon may be an adaptive response contributing to cell survival. In this study, we show that the RpoS regulon is primarily induced by MMC-induced ROS production. We also show that RpoS regulon induction is required for the survival of MMC-treated growing cells. The major contributor to RpoS-dependent resistance to MMC treatment is DNA polymerase Pol II, which is encoded by the polB gene belonging to the SOS regulon. The observation that polB gene expression is controlled by the two major stress response regulons that are required to maximize survival and fitness further emphasizes the key role of this DNA polymerase as an important factor in genome stability. Copyright © 2017 by the Genetics Society of America.

  17. Deployment and Performance of an X-Band Dual-Polarization Radar during the Southern China Monsoon Rainfall Experiment

    Directory of Open Access Journals (Sweden)

    Zhao Shi

    2017-12-01

    Full Text Available An X-band dual-polarization radar (XPRAD was deployed in Guangdong province as part of the Southern China Monsoon Rainfall Experiment (SCMREX during the storm season in 2016. This paper presents a comprehensive assessment of XPRAD observations during SCMREX with emphasis on data processing and rainfall products. The differential phase-based attenuation correction and radar calibration using self-consistency of dual-polarization observables are presented. It is found that the standard deviation of the Z d r bias is less than 0.2 dB based on ‘light rain at low angle’ and ‘dry aggregate snow’ observations. Cross-comparison with two standard S-band China New Generation Weather Radars (CINRAD shows that the bias of Z h has a mean value less than 1.5 dBZ and a standard deviation less than 0.5 dBZ. In addition, fifteen rainfall events that occurred during the intensive observing period (IOP are analyzed to demonstrate the rainfall estimation performance of XPRAD. In particular, rainfall accumulations at 1-, 2- and 3-h scales derived using R( K d p and R( Z h , Z d r relations are evaluated using national level rain gauge data and CINRAD-based rainfall estimation. The results show that both R( K d p - and R( Z h , Z d r -based products agree well with the rain gauge observations and CINRAD estimation. The difference between R ( K d p and R ( Z h , Z d r is not significant, although R ( K d p shows slightly better performance than R ( Z h , Z d r .

  18. Fpga based L-band pulse doppler radar design and implementation

    Science.gov (United States)

    Savci, Kubilay

    As its name implies RADAR (Radio Detection and Ranging) is an electromagnetic sensor used for detection and locating targets from their return signals. Radar systems propagate electromagnetic energy, from the antenna which is in part intercepted by an object. Objects reradiate a portion of energy which is captured by the radar receiver. The received signal is then processed for information extraction. Radar systems are widely used for surveillance, air security, navigation, weather hazard detection, as well as remote sensing applications. In this work, an FPGA based L-band Pulse Doppler radar prototype, which is used for target detection, localization and velocity calculation has been built and a general-purpose Pulse Doppler radar processor has been developed. This radar is a ground based stationary monopulse radar, which transmits a short pulse with a certain pulse repetition frequency (PRF). Return signals from the target are processed and information about their location and velocity is extracted. Discrete components are used for the transmitter and receiver chain. The hardware solution is based on Xilinx Virtex-6 ML605 FPGA board, responsible for the control of the radar system and the digital signal processing of the received signal, which involves Constant False Alarm Rate (CFAR) detection and Pulse Doppler processing. The algorithm is implemented in MATLAB/SIMULINK using the Xilinx System Generator for DSP tool. The field programmable gate arrays (FPGA) implementation of the radar system provides the flexibility of changing parameters such as the PRF and pulse length therefore it can be used with different radar configurations as well. A VHDL design has been developed for 1Gbit Ethernet connection to transfer digitized return signal and detection results to PC. An A-Scope software has been developed with C# programming language to display time domain radar signals and detection results on PC. Data are processed both in FPGA chip and on PC. FPGA uses fixed

  19. Detection of hail signatures from single-polarization C-band radar reflectivity

    Science.gov (United States)

    Kunz, Michael; Kugel, Petra I. S.

    2015-02-01

    Five different criteria that estimate hail signatures from single-polarization radar data are statistically evaluated over a 15-year period by categorical verification against loss data provided by a building insurance company. The criteria consider different levels or thresholds of radar reflectivity, some of them complemented by estimates of the 0 °C level or cloud top temperature. Applied to reflectivity data from a single C-band radar in southwest Germany, it is found that all criteria are able to reproduce most of the past damage-causing hail events. However, the criteria substantially overestimate hail occurrence by up to 80%, mainly due to the verification process using damage data. Best results in terms of highest Heidke Skill Score HSS or Critical Success Index CSI are obtained for the Hail Detection Algorithm (HDA) and the Probability of Severe Hail (POSH). Radar-derived hail probability shows a high spatial variability with a maximum on the lee side of the Black Forest mountains and a minimum in the broad Rhine valley.

  20. La persistencia de las diferencias de género en el interés por la política

    Directory of Open Access Journals (Sweden)

    TÀNIA VERGE MESTRE

    2012-01-01

    Full Text Available Este artículo explora el rol de los recursos individuales, los factores situacionales y el proceso de socialización en la persistencia de las diferencias de género en las actitudes políticas, principalmente en el interés por la política. Prestamos especial atención a los factores situacionales, sobre todo aquellos que tienen que ver con el tiempo dedicado a las responsabilidades domésticas y de cuidado. A pesar de la creciente participación de la mujer en el mercado de trabajo y la progresiva equiparación en el nivel educativo de hombres y mujeres, la persistente desigualdad en la división sexual del trabajo doméstico reduce el tiempo libre de las mujeres así como las habilidades, recursos y conexiones sociales que podrían fomentar su implicación política, contribuyendo a mantener las diferencias de género en el interés por la política.

  1. Intercomparison of Vertical Structure of Storms Revealed by Ground-Based (NMQ and Spaceborne Radars (CloudSat-CPR and TRMM-PR

    Directory of Open Access Journals (Sweden)

    Veronica M. Fall

    2013-01-01

    Full Text Available Spaceborne radars provide great opportunities to investigate the vertical structure of clouds and precipitation. Two typical spaceborne radars for such a study are the W-band Cloud Profiling Radar (CPR and Ku-band Precipitation Radar (PR, which are onboard NASA’s CloudSat and TRMM satellites, respectively. Compared to S-band ground-based radars, they have distinct scattering characteristics for different hydrometeors in clouds and precipitation. The combination of spaceborne and ground-based radar observations can help in the identification of hydrometeors and improve the radar-based quantitative precipitation estimation (QPE. This study analyzes the vertical structure of the 18 January, 2009 storm using data from the CloudSat CPR, TRMM PR, and a NEXRAD-based National Mosaic and Multisensor QPE (NMQ system. Microphysics above, within, and below the melting layer are studied through an intercomparison of multifrequency measurements. Hydrometeors’ type and their radar scattering characteristics are analyzed. Additionally, the study of the vertical profile of reflectivity (VPR reveals the brightband properties in the cold-season precipitation and its effect on the radar-based QPE. In all, the joint analysis of spaceborne and ground-based radar data increases the understanding of the vertical structure of storm systems and provides a good insight into the microphysical modeling for weather forecasts.

  2. Summary and Analysis of the U.S. Government Bat Banding Program

    Science.gov (United States)

    Ellison, Laura E.

    2008-01-01

    This report summarizes the U.S. Government Bat Banding Program (BBP) from 1932 to 1972. More than 2 million bands were issued during the program, of which approximately 1.5 million bands were applied to 36 bat species by scientists in many locations in North America including the U.S., Canada, Mexico, and Central America. Throughout the BBP, banders noticed numerous and deleterious effects on bats, leading to a moratorium on bat banding by the U.S. Fish and Wildlife Service, and a resolution to cease banding by the American Society of Mammalogists in 1973. One of the main points of the memorandum written to justify the moratorium was to conduct a 'detailed evaluation of the files of the bat-banding program.' However, a critical and detailed evaluation of the BBP was never completed. In an effort to satisfy this need, I compiled a detailed history of the BBP by examining the files and conducting a literature review on bat banding activities during the program. I also provided a case study in managing data and applying current mark-recapture theory to estimate survival using the information from a series of bat bands issued to Clyde M. Senger during the BBP. The majority of bands applied by Senger were to Townsend's big-eared bat (Corynorhinus townsendii), a species of special concern for many states within its geographic range. I developed a database management system for the bat banding records and then analyzed and modeled survival of hibernating Townsend's big-eared bats at three main locations in Washington State using Cormack-Jolly-Seber (CJS) open models and the modeling capabilities of Program MARK. This analysis of a select dataset in the BBP files provided relatively precise estimates of survival for wintering Townsend's big-eared bats. However, this dataset is unique due to its well-maintained and complete state and because there were high recapture rates over the course of banding; it is doubtful that other unpublished datasets of the same quality exist

  3. Karyotype characterization of Crotalaria juncea (L. by chromosome banding and physical mapping of 18S-5.8S-26S and 5S rRNA gene sites

    Directory of Open Access Journals (Sweden)

    Mateus Mondin

    2007-01-01

    Full Text Available The chromosomes of Crotalaria juncea, a legume of agronomic interest with a 2n = 16 karyotype composed of metacentric chromosomes, were analyzed using several cytogenetic techniques. C-banding revealed heterochromatic regions around the centromeres in all chromosomes and adjacent to the secondary constriction on the chromosome 1 short arm. Fluorescent staining with the GC-specific chromomycin A3 (CMA highlighted these heterochromatic regions and a tiny site on the chromosome 1 long arm while the AT-specific stain 4'-6-diamidino-2-phenylindole (DAPI induced a reversed pattern. Staining with CMA combined with AT-specific distamycin A (DA counterstaining quenched the pericentromeric regions of all chromosomes, but enhanced fluorescence was observed at the heterochromatic regions around the secondary constriction and on the long arms of chromosomes 1 and 4. Fluorescence in situ hybridization (FISH revealed 18S-5.8S-26S rRNA gene sites (45S rDNA on chromosomes 1 and 4, and one 5S rDNA locus on chromosome 1. All the rDNA sites were co-located with the positive-CMA/DA bands, suggesting they were very rich in GC. Silver staining revealed signals at the main 45S rDNA locus on chromosome 1 and, in some cells, chromosome 4 was labeled. Two small nucleoli were detected in a few interphase cells, suggesting that the minor site on chromosome 4 could be active at some stages of the cell cycle.

  4. Theoretical Modeling and Analysis of L- and P-band Radar Backscatter Sensitivity to Soil Active Layer Dielectric Variations

    Directory of Open Access Journals (Sweden)

    Jinyang Du

    2015-07-01

    Full Text Available Freeze-thaw (FT and moisture dynamics within the soil active layer are critical elements of boreal, arctic and alpine ecosystems, and environmental change assessments. We evaluated the potential for detecting dielectric changes within different soil layers using combined L- and P-band radar remote sensing as a prerequisite for detecting FT and moisture profile changes within the soil active layer. A two-layer scattering model was developed and validated for simulating radar responses from vertically inhomogeneous soil. The model simulations indicated that inhomogeneity in the soil dielectric profile contributes to both L- and P-band backscatter, but with greater P-band sensitivity at depth. The difference in L- and P-band responses to soil dielectric profile inhomogeneity appears suitable for detecting associated changes in soil active layer conditions. Additional evaluation using collocated airborne radar (AIRSAR observations and in situ soil moisture measurements over alpine tundra indicates that combined L- and P-band SAR observations are sensitive to soil dielectric profile heterogeneity associated with variations in soil moisture and FT conditions.

  5. Robust flood area detection using a L-band synthetic aperture radar: Preliminary application for Florida, the U.S. affected by Hurricane Irma

    Science.gov (United States)

    Nagai, H.; Ohki, M.; Abe, T.

    2017-12-01

    Urgent crisis response for a hurricane-induced flood needs urgent providing of a flood map covering a broad region. However, there is no standard threshold values for automatic flood identification from pre-and-post images obtained by satellite-based synthetic aperture radars (SARs). This problem could hamper prompt data providing for operational uses. Furthermore, one pre-flood SAR image does not always represent potential water surfaces and river flows especially in tropical flat lands which are greatly influenced by seasonal precipitation cycle. We are, therefore, developing a new method of flood mapping using PALSAR-2, an L-band SAR, which is less affected by temporal surface changes. Specifically, a mean-value image and a standard-deviation image are calculated from a series of pre-flood SAR images. It is combined with a post-flood SAR image to obtain normalized backscatter amplitude difference (NoBADi), with which a difference between a post-flood image and a mean-value image is divided by a standard-deviation image to emphasize anomalous water extents. Flooding areas are then automatically obtained from the NoBADi images as lower-value pixels avoiding potential water surfaces. We applied this method to PALSAR-2 images acquired on Sept. 8, 10, and 12, 2017, covering flooding areas in a central region of Dominican Republic and west Florida, the U.S. affected by Hurricane Irma. The output flooding outlines are validated with flooding areas manually delineated from high-resolution optical satellite images, resulting in higher consistency and less uncertainty than previous methods (i.e., a simple pre-and-post flood difference and pre-and-post coherence changes). The NoBADi method has a great potential to obtain a reliable flood map for future flood hazards, not hampered by cloud cover, seasonal surface changes, and "casual" thresholds in the flood identification process.

  6. Advances in X-Band and S-Band Linear Accelerators for Security, NDT, and Other Applications

    CERN Document Server

    Mishin, Andrey V

    2005-01-01

    At AS&E High Energy Systems Division, we designed several new advanced high energy electron beam and X-ray sources. Our primary focus has always been in building the world's most portable commercial X-band accelerators. Today, our X-band systems frequently exceed performance of the similar S-band machines, while they are more portable compared to the latter. The new designs of the X-band accelerators in the most practical energy range from 1 MeV to 6 MeV have been tested delivering outstanding results. Seventy 6 MeV X-band linacs systems have been produced. The most compact linac for security is used by AS&E in a self-shielded, Shaped Energy™ cargo screening system. We pioneered using the X-band linear accelerators for CT, producing high quality images of oil pipes and wood logs. An X-band linear accelerator head on a robotic arm has been used for electron beam radiation curing of an odd-shaped graphite composite part. We developed the broad-range 4 MeV to over 10 MeV energy-regulated X-band ...

  7. A new low-cost 10 ns pulsed K(a)-band radar.

    Science.gov (United States)

    Eskelinen, Pekka; Ylinen, Juhana

    2011-07-01

    Two Gunn oscillators, conventional intermediate frequency building blocks, and a modified GaAs diode detector are combined to form a portable monostatic 10 ns instrumentation radar for outdoor K(a)-band radar cross section measurements. At 37.8 GHz the radar gives +20 dBm output power and its tangential sensitivity is -76 dBm. Processing bandwidth is 125 MHz, which also allows for some frequency drift in the Gunn devices. Intra-pulse frequency chirp is less than 15 MHz. All functions are steered by a microcontroller. First measurements convince that the construction has a reasonable ability to reduce close-to-ground surface clutter and gives an effective way of resolving target detail. This is beneficial especially when amplitude fluctuations disturb measurements with longer pulses. The new unit operates on 12 V dc, draws a current of less than 3 A, and weighs 5 kg.

  8. The Use of C-/X-Band Time-Gapped SAR Data and Geotechnical Models for the Study of Shanghai’s Ocean-Reclaimed Lands through the SBAS-DInSAR Technique

    Directory of Open Access Journals (Sweden)

    Antonio Pepe

    2016-11-01

    Full Text Available In this work, we investigate the temporal evolution of ground deformation affecting the ocean-reclaimed lands of the Shanghai (China megacity, from 2007 to 2016, by applying the Differential Synthetic Aperture Radar Interferometry (DInSAR technique known as the Small BAseline Subset (SBAS algorithm. For the analysis, we exploited two sets of non-time-overlapped synthetic aperture radar (SAR data, acquired from 2007 to 2010, by the ASAR/ENVISAT (C-band instrument, and from 2014 to 2016 by the X-band COSMO-SkyMed (CSK sensors. The long time gap (of about three years existing between the available C- and X-band datasets made the generation of unique displacement time-series more difficult. Nonetheless, this problem was successfully solved by benefiting from knowledge of time-dependent geotechnical models, which describe the temporal evolution of the expected deformation affecting Shanghai’s ocean-reclaimed platforms. The combined ENVISAT/CSK (vertical deformation time-series were analyzed to gain insight into the future evolution of displacement signals within the investigated area. As an outcome, we find that ocean-reclaimed lands in Shanghai experienced, between 2007 and 2016, average cumulative (vertical displacements extending down to 25 centimeters.

  9. A microscopic study of the S band in the generator co-ordinate approach

    International Nuclear Information System (INIS)

    Wuest, E.; Ansari, A.

    1985-04-01

    Using particle number and spin projected cranked Hartree-Fock-Bogolubov (CHFB) wave functions in the generator co-ordinate method (GCM) with the cranking frequency as a GC the shortcomings of the usual CHFB theory are removed and the ground as well as the s band are studied simultaneously. In particular, low-spin properties of the s band are discussed for a backbending nucleus 158 Dy. (author)

  10. A Novel Fusion-Based Ship Detection Method from Pol-SAR Images

    Directory of Open Access Journals (Sweden)

    Wenguang Wang

    2015-09-01

    Full Text Available A novel fusion-based ship detection method from polarimetric Synthetic Aperture Radar (Pol-SAR images is proposed in this paper. After feature extraction and constant false alarm rate (CFAR detection, the detection results of HH channel, diplane scattering by Pauli decomposition and helical factor by Barnes decomposition are fused together. The confirmed targets and potential target pixels can be obtained after the fusion process. Using the difference degree of the target, potential target pixels can be classified. The fusion-based ship detection method works accurately by utilizing three different features comprehensively. The result of applying the technique to measured Airborne Synthetic Radar (AIRSAR data shows that the novel detection method can achieve better performance in both ship’s detection and ship’s shape preservation compared to the result of K-means clustering method and the Notch Filter method.

  11. Improving Weather Radar Precipitation Estimates by Combining two Types of Radars

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ellerbæk; Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2014-01-01

    This paper presents a demonstration of how Local Area Weather Radar (LAWR) X-band measurements can be combined with meteorological C–band measurements into a single radar product. For this purpose, a blending method has been developed which combines the strengths of the two radar systems. Combining...... the two radar types achieves a radar product with both long range and high temporal resolution. It is validated that the blended radar product performs better than the individual radars based on ground observations from laser disdrometers. However, the data combination is challenged by lower performance...... of the LAWR. Although both radars benefits from the data combination, it is also found that advection based temporal interpolation is a more favourable method for increasing the temporal resolution of meteorological C–band measurements....

  12. Observatorio de Política Internacional II. AMERICAS - Elecciones en U.S.A.

    OpenAIRE

    Neira Fernández, Enrique

    2007-01-01

    Observatorio de Política Internacional II. AMÉRICAS (Neira Fernández, Enrique) RECIENTES Año 2008 Nicaragua. Un remedo revolucionario Bolivia. ¿Una o dislocada? Paraguay. El ex obispo presidente Perú. El rojo sangre de sendero luminoso Estados Unidos. Panorama tras las elecciones primarias RECIENTES Año 2007 Argentina. Contundente triunfo de Cristina Fernández Bolivia. Nuevos rumbos ¡no más embrollo! Ecuador. Nueva constitución, nuevo rumbo Guatemala....

  13. A comparison of the chromosome G-banding pattern in two Sorex species, S. satunini and S. araneus (Mammalia, Insectivora

    Directory of Open Access Journals (Sweden)

    Yuri Borisov

    2012-08-01

    Full Text Available The G-banded karyotype of S. satunini was compared with the karyotype of Sorex araneus. Extensive homology was revealed. The major chromosomal rearrangements involved in the evolutionary divergence of these species have been identified as centric fusions and centromeric shifts. From the known palaeontological age of S. satunini it is obvious that the vast chromosomal polymorphism of the S. araneus group originated during the middle Pleistocene.

  14. Shuttle orbiter Ku-band radar/communications system design evaluation. Deliverable test equipment evaluation

    Science.gov (United States)

    Maronde, R. G.

    1980-07-01

    The Ku-band test equipment, known as the Deliverable System Test equipment (DSTE), is reviewed and evaluated. The DSTE is semiautomated and computer programs were generated for 14 communication mode tests and 17 radar mode tests. The 31 test modules provide a good cross section of tests with which to exercise the Ku-band system; however, it is very limited when being used to verify Ku-band system performance. More detailed test descriptions are needed, and a major area of concern is the DSTE sell-off procedure which is inadequate.

  15. Multifractal analysis of different hydrological products of X-band radar

    Science.gov (United States)

    Skouri-Plakali, Ilektra; Da Silva Rocha Paz, Igor; Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2017-04-01

    Rainfall is widely considered as the hydrological process that triggers all the others. Its accurate measurements are crucial especially when they are used afterwards for the hydrological modeling of urban and peri-urban catchments for decision-making. Rainfall is a complex process and is scale dependent in space and time. Hence a high spatial and temporal resolution of the data is more appropriate for urban modeling. Therefore, a great interest of high-resolution measurements of precipitation in space and time is manifested. Radar technologies have not stopped evolving since their first appearance about the mid-twentieth. Indeed, the turning point work by Marshall-Palmer (1948) has established the Z - R power-law relation that has been widely used, with major scientific efforts being devoted to find "the best choice" of the two associated parameters. Nowadays X-band radars, being provided with dual-polarization and Doppler means, offer more accurate data of higher resolution. The fact that drops are oblate induces a differential phase shift between the two polarizations. The quantity most commonly used for the rainfall rate computation is actually the specific differential phase shift, which is the gradient of the differential phase shift along the radial beam direction. It is even stronger correlated to the rain rate R than reflectivity Z. Hence the rain rate can be computed with a different power-law relation, which again depends on only two parameters. Furthermore, an attenuation correction is needed to adjust the loss of radar energy due to the absorption and scattering as it passes through the atmosphere. Due to natural variations of reflectivity with altitude, vertical profile of reflectivity should be corrected as well. There are some other typical radar data filtering procedures, all resulting in various hydrological products. In this work, we use the Universal Multifractal framework to analyze and to inter-compare different products of X-band radar

  16. Effects of surface roughness on sea ice freeboard retrieval with an Airborne Ku-Band SAR radar altimeter

    DEFF Research Database (Denmark)

    Hendricks, Stefan; Stenseng, Lars; Helm, Veit

    2010-01-01

    to investigate sea ice volume changes on an Arctic wide scale. Freeboard retrieval requires precise radar range measurements to the ice surface, therefore we investigate the penetration of the Ku-Band radar waves into the overlying snow cover as well as the effects of sub-footprint-scale surface roughness using...... airborne radar and laser altimeters. We find regional variable penetration of the radar signal at late spring conditions, where the difference of the radar and the reference laser range measurement never agrees with the expected snow thickness. In addition, a rough surface can lead to biases...

  17. Installation and Initial Operation of DOE's 449-MHz Wind Profiling Radars on the U.S. West Coast

    Energy Technology Data Exchange (ETDEWEB)

    Flaherty, Julia E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shaw, William J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Morris, Victor R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wilczak, J. M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); White, A. B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ayers, Tom [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jordan, Jim [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); King, Clark W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-30

    The U.S. Department of Energy (DOE), in collaboration with the National Oceanic and Atmospheric Administration (NOAA), has recently completed the installation of three new wind profiling radars on the Washington and Oregon coasts. These systems operate at a frequency of 449 MHz and provide mean wind profiles to a height of roughly 8 km, with the maximum measurement height depending on time-varying atmospheric conditions. This is roughly half the depth of the troposphere at these latitudes. Each system is also equipped with a radio acoustic sounding system (RASS), which provides a measure of the temperature profile to heights of approximately 2 km. Other equipment deployed alongside the radar includes a surface meteorological station and GPS for column water vapor. This project began in fiscal year 2014, starting with equipment procurements and site selection. In addition, environmental reviews, equipment assembly and testing, site access agreements, and infrastructure preparations have been performed. Finally, with equipment deployment with data collection and dissemination, the primary tasks of this project have been completed. The three new wind profiling radars have been deployed at airports near Coos Bay, OR, and Astoria, OR, and at an industrial park near Forks, WA. Data are available through the NOAA Earth Systems Research Laboratory Data Display website, and will soon be made available through the DOE Atmosphere to Electrons data archive and portal as well.

  18. GPM GROUND VALIDATION DUAL POLARIZED C-BAND DOPPLER RADAR KING CITY GCPEX V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Dual Polarized C-Band Doppler Radar King City GCPEx dataset has special Range Height Indicator (RHI) and sector scans of several dual...

  19. Life test on indigenous s-band pulsed magnetron

    International Nuclear Information System (INIS)

    Wanmode, Y.D.; Shrivastava, P.; Hannurkar, P.R.

    1999-01-01

    A 2 MW S-band pulsed magnetron has been developed under joint collaboration between CAT and CEERI. In this development effort several lab prototypes were evaluated on 2 MW microwave test facility developed at CAT. One magnetron is subjected to life test. The present paper describes the setup and procedures used for life test. Various observations and corrections made during the life tests are also described. Results of the tests are discussed. (author)

  20. Improving Radar Quantitative Precipitation Estimation over Complex Terrain in the San Francisco Bay Area

    Science.gov (United States)

    Cifelli, R.; Chen, H.; Chandrasekar, V.

    2017-12-01

    A recent study by the State of California's Department of Water Resources has emphasized that the San Francisco Bay Area is at risk of catastrophic flooding. Therefore, accurate quantitative precipitation estimation (QPE) and forecast (QPF) are critical for protecting life and property in this region. Compared to rain gauge and meteorological satellite, ground based radar has shown great advantages for high-resolution precipitation observations in both space and time domain. In addition, the polarization diversity shows great potential to characterize precipitation microphysics through identification of different hydrometeor types and their size and shape information. Currently, all the radars comprising the U.S. National Weather Service (NWS) Weather Surveillance Radar-1988 Doppler (WSR-88D) network are operating in dual-polarization mode. Enhancement of QPE is one of the main considerations of the dual-polarization upgrade. The San Francisco Bay Area is covered by two S-band WSR-88D radars, namely, KMUX and KDAX. However, in complex terrain like the Bay Area, it is still challenging to obtain an optimal rainfall algorithm for a given set of dual-polarization measurements. In addition, the accuracy of rain rate estimates is contingent on additional factors such as bright band contamination, vertical profile of reflectivity (VPR) correction, and partial beam blockages. This presentation aims to improve radar QPE for the Bay area using advanced dual-polarization rainfall methodologies. The benefit brought by the dual-polarization upgrade of operational radar network is assessed. In addition, a pilot study of gap fill X-band radar performance is conducted in support of regional QPE system development. This paper also presents a detailed comparison between the dual-polarization radar-derived rainfall products with various operational products including the NSSL's Multi-Radar/Multi-Sensor (MRMS) system. Quantitative evaluation of various rainfall products is achieved

  1. Compton profiles and band structure calculations of CdS and CdTe

    International Nuclear Information System (INIS)

    Heda, N.L.; Mathur, S.; Ahuja, B.L.; Sharma, B.K.

    2007-01-01

    In this paper we present the isotropic Compton profiles of zinc-blende CdS and CdTe measured at an intermediate resolution of 0.39 a.u. using our 20 Ci 137 Cs Compton spectrometer. The electronic band structure calculations for both the zinc-blende structure compounds and also wurtzite CdS have been undertaken using various schemes of ab-initio linear combination of atomic orbitals calculations implemented in CRYSTAL03 code. The band structure and Mulliken's populations are reported using density functional scheme. In case of wurtzite CdS, our theoretical anisotropies in directional Compton profiles are compared with available experimental data. In case of both the zinc-blende compounds, the isotropic experimental profiles are found to be in better agreement with the present Hartree-Fock calculations. A study of the equal-valence-electron-density experimental profiles of zinc-blende CdS and CdTe shows that the CdS is more ionic than CdTe. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Simulation study of the high intensity S-Band photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiongwei; Nakajima, Kazuhisa [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    2001-10-01

    In this paper, we report the results of simulation study of the high intensity S-Band photoinjector. The aim of the simulation study is to transport high bunch charge with low emittance evolution. The simulation result shows that 7nC bunch with rms emittance 22.3 {pi} mm mrad can be outputted at the exit of photoinjector. (author)

  3. Simulation study of the high intensity S-Band photoinjector

    International Nuclear Information System (INIS)

    Zhu, Xiongwei; Nakajima, Kazuhisa

    2001-01-01

    In this paper, we report the results of simulation study of the high intensity S-Band photoinjector. The aim of the simulation study is to transport high bunch charge with low emittance evolution. The simulation result shows that 7nC bunch with rms emittance 22.3 π mm mrad can be outputted at the exit of photoinjector. (author)

  4. Iran’s Nuclear Future: Critical U.S. Policy Choices

    Science.gov (United States)

    2011-01-01

    embargo as an act of war, and it could respond by attempting to close the Strait of Hormuz, using mines , antiship cruise missiles, or fast patrol boats...even it means we have to compromise on sovereignty by having U.S. troops deployed here” (quoted in Barbara Opall -Rome, “U.S. to Deploy Radar, Troops...2009. As of January 13, 2011: http://handle.dtic.mil/100.2/ADA510110 Opall -Rome, Barbara, “U.S. to Deploy Radar, Troops in Israel,” Defense News, August

  5. Cd-free buffer layer materials on Cu2ZnSn(SxSe1-x)4: Band alignments with ZnO, ZnS, and In2S3

    Science.gov (United States)

    Barkhouse, D. Aaron R.; Haight, Richard; Sakai, Noriyuki; Hiroi, Homare; Sugimoto, Hiroki; Mitzi, David B.

    2012-05-01

    The heterojunctions formed between Cu2ZnSn(SxSe1-x)4 (CZTSSe) and three Cd-free n-type buffers, ZnS, ZnO, and In2S3, were studied using femtosecond ultraviolet photoemission and photovoltage spectroscopy. The electronic properties including the Fermi level location at the interface, band bending in the CZTSSe substrate, and valence and conduction band offsets were determined and correlated with device properties. We also describe a method for determining the band bending in the buffer layer and demonstrate this for the In2S3/CZTSSe system. The chemical bath deposited In2S3 buffer is found to have near optimal conduction band offset (0.15 eV), enabling the demonstration of Cd-free In2S3/CZTSSe solar cells with 7.6% power conversion efficiency.

  6. Ultra-Broad Band Radar Cross Section Reduction of Waveguide Slot Antenna with Metamaterials

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2016-06-01

    Full Text Available To reduce the radar cross section of a waveguide slot antenna, a three-layer metamaterial is presented based on orthogonal double split-ring resonators. The absorption characteristics of three-layer metamaterial are demonstrated by simulation. Moreover, the metamaterials have been loaded on common waveguide slot antenna according to the surface current distribution. The ultra-broad band radar cross section reduction of the antenna with metamaterials had been theoretically and experimentally investigated by radiating and scattering performances. Experimental and simulated results showed that the proposed antenna with metamaterials performed broadband radar cross section reduction from 3.9 GHz to 18 GHz and the gain had been improved due to the coupling effect between slot and the period structure. The maximal radar cross section reduction achieved 17.81 dB at 8.68 GHz for x-polarized incidence and 21.79 dB at 6.25 GHz for y-polarized waves.

  7. a Novel Two-Component Decomposition for Co-Polar Channels of GF-3 Quad-Pol Data

    Science.gov (United States)

    Kwok, E.; Li, C. H.; Zhao, Q. H.; Li, Y.

    2018-04-01

    Polarimetric target decomposition theory is the most dynamic and exploratory research area in the field of PolSAR. But most methods of target decomposition are based on fully polarized data (quad pol) and seldom utilize dual-polar data for target decomposition. Given this, we proposed a novel two-component decomposition method for co-polar channels of GF-3 quad-pol data. This method decomposes the data into two scattering contributions: surface, double bounce in dual co-polar channels. To save this underdetermined problem, a criterion for determining the model is proposed. The criterion can be named as second-order averaged scattering angle, which originates from the H/α decomposition. and we also put forward an alternative parameter of it. To validate the effectiveness of proposed decomposition, Liaodong Bay is selected as research area. The area is located in northeastern China, where it grows various wetland resources and appears sea ice phenomenon in winter. and we use the GF-3 quad-pol data as study data, which which is China's first C-band polarimetric synthetic aperture radar (PolSAR) satellite. The dependencies between the features of proposed algorithm and comparison decompositions (Pauli decomposition, An&Yang decomposition, Yamaguchi S4R decomposition) were investigated in the study. Though several aspects of the experimental discussion, we can draw the conclusion: the proposed algorithm may be suitable for special scenes with low vegetation coverage or low vegetation in the non-growing season; proposed decomposition features only using co-polar data are highly correlated with the corresponding comparison decomposition features under quad-polarization data. Moreover, it would be become input of the subsequent classification or parameter inversion.

  8. Monarcas, bufones, políticos y audiencias. Comparación de la sátira televisiva en Reino Unido y España

    Directory of Open Access Journals (Sweden)

    José-Luis Valhondo-Crego

    2011-01-01

    Full Text Available Los programas de sátira se han convertido en una forma de comunicación política frecuente en la televisión. Tras la liberalización de los medios y la globalización de los formatos, países como España han adoptado formatos satíricos procedentes de otros que, como Reino Unido, contaban con una tradición que se remontaba casi al inicio de la televisión. El objetivo de este artículo es el de pergeñar una definición del género teniendo en cuenta los ejemplos de los dos países mencionados y, también, refiriéndonos a dos épocas separadas por el fenómeno de la liberalización de la televisión. Aplicaremos para ello una metodología comparativa respecto al perfil de las audiencias, de los bufones de la sátira y del papel jugado por la clase política a lo largo de la corta historia de la sátira en televisión. Los resultados señalan una evolución. En los años sesenta del siglo XX, el género apuntaba a las clases medias, sus autores pretendían popularizar la política para una sociedad muy respetuosa con el establishment y los políticos censuraron el espacio en previsión de que pudiera desequilibrar ideológicamente los procesos electorales. En los años noventa, las audiencias de la sátira se redujeron al segmento más lucrativo de los jóvenes adultos, los bufones adquirieron el mayor protagonismo y los políticos no sólo se inmunizaron a la sátira sino que parecieron sacar provecho de ella.

  9. RF processing of an S-band high gradient accelerator unit

    International Nuclear Information System (INIS)

    Morita, S.

    1994-01-01

    A 3m-long S-band accelerating structure is used in 1.54 GeV Linac of Accelerator Test Facility. The accelerating structure should be processed up to 200 MW which produce 52 MV/m accelerating gradient. The process of RF processing is described. (author)

  10. Band-gap and sub-band-gap photoelectrochemical processes at nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

    International Nuclear Information System (INIS)

    Malashchonak, M.V.; Streltsov, E.A.; Mazanik, A.V.; Kulak, A.I.; Poznyak, S.K.; Stroyuk, O.L.; Kuchmiy, S.Ya.; Gaiduk, P.I.

    2015-01-01

    Cadmium sulfide nanoparticle (NP) deposition by the successive ionic layer adsorption and reaction (SILAR) method on the surface of mesoporous ZnO micro-platelets with a large specific surface area (110 ± 10 m 2 g −1 ) results in the formation of ZnO/CdS heterostructures exhibiting a high incident photon-to-current conversion efficiency (Y) not only within the region of CdS fundamental absorption (Y max = 90%; 0.1 M Na 2 S + 0.1 M Na 2 SO 3 ), but also in the sub-band-gap (SBG) range (Y max = 25%). The onset potentials of SBG photoelectrochemical processes are more positive than the band-gap (BG) onset potential by up to 100 mV. A maximum incident photon-to-current conversion efficiency value for SBG processes is observed at larger amount of deposited CdS in comparison with the case of BG ones. The Urbach energy (E U ) of CdS NPs determined from the photocurrent spectra reaches a maximal value on an early deposition stage (E U = 93 mV at SILAR cycle number N = 5), then lowers somewhat (E U = 73 mV at N = 10) and remains steady in the range of N from 20 to 300 (E U = 67 ± 1 mV). High efficiency of the photoelectrochemical SBG processes are interpreted in terms of light scattering in the ZnO/CdS heterostructures. - Highlights: • ZnO/CdS films demonstrate high quantum efficiency (25%) for sub-band-gap transitions. • Onset photocurrent potentials for sub-band-gap processes differ than those for band-gap ones. • Sub-band-gap transitions are caused by band-tail states in CdS nanoparticles

  11. Band-gap and sub-band-gap photoelectrochemical processes at nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Malashchonak, M.V., E-mail: che.malasche@gmail.com [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Streltsov, E.A., E-mail: streltea@bsu.by [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Mazanik, A.V. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Kulak, A.I., E-mail: kulak@igic.bas-net.by [Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Surganova str., 9/1, Minsk 220072 (Belarus); Poznyak, S.K. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Stroyuk, O.L., E-mail: stroyuk@inphyschem-nas.kiev.ua [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 prosp. Nauky, 03028 Kyiv (Ukraine); Kuchmiy, S.Ya. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 prosp. Nauky, 03028 Kyiv (Ukraine); Gaiduk, P.I. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus)

    2015-08-31

    Cadmium sulfide nanoparticle (NP) deposition by the successive ionic layer adsorption and reaction (SILAR) method on the surface of mesoporous ZnO micro-platelets with a large specific surface area (110 ± 10 m{sup 2}g{sup −1}) results in the formation of ZnO/CdS heterostructures exhibiting a high incident photon-to-current conversion efficiency (Y) not only within the region of CdS fundamental absorption (Y{sub max} = 90%; 0.1 M Na{sub 2}S + 0.1 M Na{sub 2}SO{sub 3}), but also in the sub-band-gap (SBG) range (Y{sub max} = 25%). The onset potentials of SBG photoelectrochemical processes are more positive than the band-gap (BG) onset potential by up to 100 mV. A maximum incident photon-to-current conversion efficiency value for SBG processes is observed at larger amount of deposited CdS in comparison with the case of BG ones. The Urbach energy (E{sub U}) of CdS NPs determined from the photocurrent spectra reaches a maximal value on an early deposition stage (E{sub U} = 93 mV at SILAR cycle number N = 5), then lowers somewhat (E{sub U} = 73 mV at N = 10) and remains steady in the range of N from 20 to 300 (E{sub U} = 67 ± 1 mV). High efficiency of the photoelectrochemical SBG processes are interpreted in terms of light scattering in the ZnO/CdS heterostructures. - Highlights: • ZnO/CdS films demonstrate high quantum efficiency (25%) for sub-band-gap transitions. • Onset photocurrent potentials for sub-band-gap processes differ than those for band-gap ones. • Sub-band-gap transitions are caused by band-tail states in CdS nanoparticles.

  12. Relat del VII Congrés Internacional sobre Internet, Dret i Política: Neutralitat de la Xarxa i dret a l'oblit

    Directory of Open Access Journals (Sweden)

    Javier de la Cueva González-Cotera

    2012-03-01

    Full Text Available

    Els dies 11 i 12 de juliol del 2011 es va celebrar a Barcelona el VII Congrés Internacional sobre Internet, Dret i Política que es va centrar en els dos temes principals de la neutralitat de la Xarxa i el dret a l'oblit. A més d'aquests continguts, els autors hi van exposar ponències relacionades amb l'última problemàtica jurídica i política l'objecte de la qual és Internet. En aquest article es fa una crònica no exhaustiva del congrés, incloses les conclusions del relator al final de cada jornada.

  13. 260 Gbit/s photonic-wireless link in the THz band

    DEFF Research Database (Denmark)

    Pang, X.; Jia, S.; Ozolins, O.

    2016-01-01

    A single-transmitter/single-receiver THz link (0.3-0.5 THz) with a record net data rate of 260 Gbit/s is experimentally demonstrated. Spectrally efficient multi-channel signal transmission is enabled by a novel frequency-band-allocation scheme with pre-and post- digital equalization....

  14. Effect of band-aligned double absorber layers on photovoltaic characteristics of chemical bath deposited PbS/CdS thin film solar cells.

    Science.gov (United States)

    Ho Yeon, Deuk; Chandra Mohanty, Bhaskar; Lee, Seung Min; Soo Cho, Yong

    2015-09-23

    Here we report the highest energy conversion efficiency and good stability of PbS thin film-based depleted heterojunction solar cells, not involving PbS quantum dots. The PbS thin films were grown by the low cost chemical bath deposition (CBD) process at relatively low temperatures. Compared to the quantum dot solar cells which require critical and multistep complex procedures for surface passivation, the present approach, leveraging the facile modulation of the optoelectronic properties of the PbS films by the CBD process, offers a simpler route for optimization of PbS-based solar cells. Through an architectural modification, wherein two band-aligned junctions are stacked without any intervening layers, an enhancement of conversion efficiency by as much as 30% from 3.10 to 4.03% facilitated by absorption of a wider range of solar spectrum has been obtained. As an added advantage of the low band gap PbS stacked over a wide gap PbS, the devices show stability over a period of 10 days.

  15. Compte rendu de Polémiques médiatiques et journalistiques. Le discours polémique en question(s

    Directory of Open Access Journals (Sweden)

    Laurence van Nuijs

    2011-10-01

    Full Text Available Le numéro 31 de Semen. Revue de sémio-linguistique des textes et discours, coordonné par Ruth Amossy (groupe de recherche de l’Analyse du discours, argumentation et rhétorique de l’Université de Tel Aviv, ADARR et Marcel Burger (Centre de linguistique et des sciences du langage de l’Université de Lausanne, CLSLest consacré à la notion de « polémique », telle que celle-ci ressort de diverses pratiques journalistiques et médiatiques récentes : forums de discussions sur internet, articles d’op...

  16. Status Update on the GPM Ground Validation Iowa Flood Studies (IFloodS) Field Experiment

    Science.gov (United States)

    Petersen, Walt; Krajewski, Witold

    2013-04-01

    The overarching objective of integrated hydrologic ground validation activities supporting the Global Precipitation Measurement Mission (GPM) is to provide better understanding of the strengths and limitations of the satellite products, in the context of hydrologic applications. To this end, the GPM Ground Validation (GV) program is conducting the first of several hydrology-oriented field efforts: the Iowa Flood Studies (IFloodS) experiment. IFloodS will be conducted in the central to northeastern part of Iowa in Midwestern United States during the months of April-June, 2013. Specific science objectives and related goals for the IFloodS experiment can be summarized as follows: 1. Quantify the physical characteristics and space/time variability of rain (rates, DSD, process/"regime") and map to satellite rainfall retrieval uncertainty. 2. Assess satellite rainfall retrieval uncertainties at instantaneous to daily time scales and evaluate propagation/impact of uncertainty in flood-prediction. 3. Assess hydrologic predictive skill as a function of space/time scales, basin morphology, and land use/cover. 4. Discern the relative roles of rainfall quantities such as rate and accumulation as compared to other factors (e.g. transport of water in the drainage network) in flood genesis. 5. Refine approaches to "integrated hydrologic GV" concept based on IFloodS experiences and apply to future GPM Integrated GV field efforts. These objectives will be achieved via the deployment of the NASA NPOL S-band and D3R Ka/Ku-band dual-polarimetric radars, University of Iowa X-band dual-polarimetric radars, a large network of paired rain gauge platforms with attendant soil moisture and temperature probes, a large network of both 2D Video and Parsivel disdrometers, and USDA-ARS gauge and soil-moisture measurements (in collaboration with the NASA SMAP mission). The aforementioned measurements will be used to complement existing operational WSR-88D S-band polarimetric radar measurements

  17. Multiple scattering effects on the Linear Depolarization Ratio (LDR) measured during CaPE by a Ka-band air-borne radar

    Science.gov (United States)

    Iguchi, Toshio; Meneghini, Robert

    1993-01-01

    Air-borne radar measurements of thunderstorms were made as part of the CaPE (Convection and Precipitation/Electrification) experiment in Florida in July 1991. The radar has two channels, X-band (10 GHz) and Ka-band (34.5 GHz), and is capable of measuring cross-polarized returns as well as co-polarized returns. In stratiform rain, the cross-polarized components can be observed only at the bright band region and from the surface reflection. The linear depolarization ratios (LDR's) measured at X-band and Ka-band at the bright band are nearly equal. In convective rain, however, the LDR in Ka-band often exceeds the X-band LDR by several dB, and sometimes by more than 10 dB, reaching LDR values of up to -5 dB over heavy convective rain. For randomly oriented hydrometeors, such high LDR values cannot be explained by single scattering from non-spherical scattering particles alone. Because the LDR by single backscatter depends weakly on the wavelength, the difference between the Ka-band and X-band LDR's suggests that multiple scattering effects prevail in the Ka-band LDR. In order to test this inference, the magnitude of the cross-polarized component created by double scattering was calculated using the parameters of the airborne radar, which for both frequencies has beamwidths of 5.1 degrees and pulse widths of 0.5 microsecond. Uniform rain beyond the range of 3 km is assumed.

  18. Comparison between HF radar current data and moored ADCP currentmeter

    International Nuclear Information System (INIS)

    Cosoli, S.

    2005-01-01

    A preliminary assessment of accuracy of a two-sites shore-based HF Radar network along the Venice Lagoon littoral was attempted by means of comparison with a 57.5 day-long ADCP current time series for the period September-October 2002. Results showed that radar measurements were accurate ( O . The main differences between the HF radar and surface ADCP currents can be explained in terms of random errors affecting the measurement technique and the daily sea breeze forcing, since low-pass filtering of current time series significantly improved the correlation and decreased the RMS of the differences between the two measured data set. Comparison of the semidiurnal (M2, S2) tidal band suggested good agreement between tidal ellipse amplitudes. Wind forcing on a daily time-scale (sea-breeze) was associated with larger differences between radar and ADCP currents at a diurnal band due to the presence of a vertical shear in the surface layer

  19. Kent’s Sweden, or what a rock band can tell us about a nation

    Directory of Open Access Journals (Sweden)

    Johansson, Ola

    2013-06-01

    Full Text Available Music can communicate a great deal about the culture and society that it comes from. This is the case with the contemporary Swedish rock band Kent, who are not only the most popular band in recent Swedish music history, but also perceived as quintessentially Swedish. Of particular importance to understand this Swedishness is the band’s origin in the city of Eskilstuna, which communicates three interrelated ideas about Sweden: Eskilstuna as an archetypical Swedish small city; the band’s humble beginnings in Eskilstuna illustrates a “class journey” that resonates in Sweden; and Kent’s migration to Stockholm has resulted in an ambivalent relationship with their hometown. The path of Kent’s career has further reinforced the notion of Kent as a Swedish band, particularly as they failed outside the Nordic countries and how their concert choices and collective public persona create associations with Swedishness. Finally, the content of Kent’s music and lyrics are rich with spatial and environmental metaphors that can be conceptualized as four different landscapes representing Sweden: an inner landscape, a public landscape, an urban landscape, and a winter landscape.

  20. Performance Analysis of Ultra-Wideband Channel for Short-Range Monopulse Radar at Ka-Band

    Directory of Open Access Journals (Sweden)

    Naohiko Iwakiri

    2012-01-01

    Full Text Available High-range resolution is inherently provided with Ka-band ultra-wideband (UWB vehicular radars. The authors have developed a prototype UWB monopulse radar equipped with a two-element receiving antenna array and reported its measurement results. In this paper, a more detailed verification using these measurements is presented. The measurements were analyzed employing matched filtering and eigendecomposition, and then multipath components were extracted to examine the behavior of received UWB monopulse signals. Next, conventional direction finding algorithms based on narrowband assumption were evaluated using the extracted multipath components, resulting in acceptable angle-of-arrival (AOA from the UWB monopulse signal regardless of wideband signals. Performance degradation due to a number of averaging the received monopulses was also examined to design suitable radar's waveforms.

  1. Direct imaging of band profile in single layer MoS2 on graphite: quasiparticle energy gap, metallic edge states, and edge band bending.

    Science.gov (United States)

    Zhang, Chendong; Johnson, Amber; Hsu, Chang-Lung; Li, Lain-Jong; Shih, Chih-Kang

    2014-05-14

    Using scanning tunneling microscopy and spectroscopy, we probe the electronic structures of single layer MoS2 on graphite. The apparent quasiparticle energy gap of single layer MoS2 is measured to be 2.15 ± 0.06 eV at 77 K, albeit a higher second conduction band threshold at 0.2 eV above the apparent conduction band minimum is also observed. Combining it with photoluminescence studies, we deduce an exciton binding energy of 0.22 ± 0.1 eV (or 0.42 eV if the second threshold is use), a value that is lower than current theoretical predictions. Consistent with theoretical predictions, we directly observe metallic edge states of single layer MoS2. In the bulk region of MoS2, the Fermi level is located at 1.8 eV above the valence band maximum, possibly due to the formation of a graphite/MoS2 heterojunction. At the edge, however, we observe an upward band bending of 0.6 eV within a short depletion length of about 5 nm, analogous to the phenomena of Fermi level pinning of a 3D semiconductor by metallic surface states.

  2. Band-structure tailoring and surface passivation for highly efficient near-infrared responsive PbS quantum dot photovoltaics

    Science.gov (United States)

    Zhou, Ru; Niu, Haihong; Ji, Fengwei; Wan, Lei; Mao, Xiaoli; Guo, Huier; Xu, Jinzhang; Cao, Guozhong

    2016-11-01

    PbS is a promising light harvester for near-infrared (NIR) responsive quantum dot (QD) photovoltaics due to its narrow bulk band gap (0.41 eV) and large exciton Bohr radius (18 nm). However, the relatively low conduction band (CB) and high-density surface defects of PbS as two major drawbacks for its use in solar cells severely hamper the photovoltaic performance enhancement. In this work, a modified solution-based successive ionic layer adsorption and reaction (SILAR) utilizing mixed cationic precursors of Pb2+ and Cd2+ is explored, and such a scheme offers two benefits, band-structure tailoring and surface passivation. In-situ deposited CdS suppresses the excessive growth of PbS in the mesopores, thereby facilitating the favorable electron injection from PbS to TiO2 in view of the up-shifted CB level of QDs; the intimate interpenetration of two sulfides with each other leads to superior passivation of trap state defects on PbS, which suppresses the interfacial charge recombination. With the construction of photovoltaics based on such a hybrid (Pb,Cd)S/CdS configuration, impressive power conversion efficiency up to 4.08% has been reached, outperforming that of the conventional PbS/CdS pattern (2.95%). This work highlights the great importance of band-structure tailoring and surface passivation for constructing highly efficient PbS QD photovoltaics.

  3. Radar Remote Sensing

    Science.gov (United States)

    Rosen, Paul A.

    2012-01-01

    This lecture was just a taste of radar remote sensing techniques and applications. Other important areas include Stereo radar grammetry. PolInSAR for volumetric structure mapping. Agricultural monitoring, soil moisture, ice-mapping, etc. The broad range of sensor types, frequencies of observation and availability of sensors have enabled radar sensors to make significant contributions in a wide area of earth and planetary remote sensing sciences. The range of applications, both qualitative and quantitative, continue to expand with each new generation of sensors.

  4. Bandwidth Extension of an S-band, Fundamental-Mode Eight-Beam Klystron

    Science.gov (United States)

    2006-04-01

    Extension of an S - band , Fundamental-Mode Eight-Beam Klystron Khanh T. Nguyen Beam-Wave Research, Inc. Bethesda, MD 20814 Dean E. Pershing ATK Mission...of a five-cavity, approximately 18 cm downstream from the center of the broadband, high - power multiple-beam klystron (MBK) first gap - the logical...the circuit generates >550 kW across the band with a peak power of more than 600 kW at -3.27 Keywords: Multiple-beam klystron ; MBK; bandwidth GHz. The 1

  5. Surface Roughness of the Moon Derived from Multi-frequency Radar Data

    Science.gov (United States)

    Fa, W.

    2011-12-01

    Surface roughness of the Moon provides important information concerning both significant questions about lunar surface processes and engineering constrains for human outposts and rover trafficabillity. Impact-related phenomena change the morphology and roughness of lunar surface, and therefore surface roughness provides clues to the formation and modification mechanisms of impact craters. Since the Apollo era, lunar surface roughness has been studied using different approaches, such as direct estimation from lunar surface digital topographic relief, and indirect analysis of Earth-based radar echo strengths. Submillimeter scale roughness at Apollo landing sites has been studied by computer stereophotogrammetry analysis of Apollo Lunar Surface Closeup Camera (ALSCC) pictures, whereas roughness at meter to kilometer scale has been studied using laser altimeter data from recent missions. Though these studies shown lunar surface roughness is scale dependent that can be described by fractal statistics, roughness at centimeter scale has not been studied yet. In this study, lunar surface roughnesses at centimeter scale are investigated using Earth-based 70 cm Arecibo radar data and miniature synthetic aperture radar (Mini-SAR) data at S- and X-band (with wavelengths 12.6 cm and 4.12 cm). Both observations and theoretical modeling show that radar echo strengths are mostly dominated by scattering from the surface and shallow buried rocks. Given the different penetration depths of radar waves at these frequencies (< 30 m for 70 cm wavelength, < 3 m at S-band, and < 1 m at X-band), radar echo strengths at S- and X-band will yield surface roughness directly, whereas radar echo at 70-cm will give an upper limit of lunar surface roughness. The integral equation method is used to model radar scattering from the rough lunar surface, and dielectric constant of regolith and surface roughness are two dominate factors. The complex dielectric constant of regolith is first estimated

  6. Band alignment of ZnO/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinke, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn; He, Jiazhu; Chen, Le; Li, Kuilong; Jia, Fang; Zeng, Yuxiang; Lu, Youming; Zhu, Deliang; Liu, Wenjun, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn [College of Materials Science and Engineering, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Zhang, Yuan [School of Physics and Electronic Information, Hua Bei Normal University, 100 Dongshan Road, Huai Bei 235000 (China); Liu, Qiang; Yu, Wenjie [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Chang Ning Road, Shanghai 200050 (China); Wu, Jing [Institute of Materials research and Engineering (IMRE), 2 Fusionopolis Way, Innovis, #08-03, 138634 Singapore (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore (Singapore)

    2016-08-15

    The energy band alignment between ZnO and multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The ZnO film was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 3.32 eV and a conduction band offset (CBO) of 1.12 eV were obtained for the ZnO/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the ZnO/ML-MoS{sub 2} interface were found to be 3.54 eV and 1.34 eV, respectively. With the CHF{sub 3} plasma treatment, the band alignment of the ZnO/ML-MoS{sub 2} interface has been changed from type II or staggered band alignment to type III or misaligned one, which favors the electron-hole pair separation. The band alignment difference is believed to be dominated by the down-shift in the core level of Zn 2p or the interface dipoles, which is caused by the interfacial layer rich in F.

  7. Induced absorption spectra of the infrared fundamental band of molecular deuterium at 77 K: S1( J)+S0( J) transitions

    International Nuclear Information System (INIS)

    Gillard, P.G.; Prasad, R.D.G.; Reddy, S.P.

    1984-01-01

    The collision-induced spectra of the fundamental band of normal D 2 in the high frequency region 3200--3700 cm -1 were recorded for gas densities in the range 80--140 amagat at 77 K with a 2 m absorption cell. The contribution to the intensity of the band in this region comes from the high frequency wings of quadrupolar transitions S 1 ( J) and Q 1 ( J)+S 0 ( J) with J = 0 and 1, and from the group of transitions S 1 (2) and Q 1 ( J)+S 0 (2) with J = 0, 1, and 2 as well as from the relatively weaker double rotational transitions of the type S 1 ( J)+S 0 ( J); the latter transitions arise from the intermolecular interaction between the anisotropic component of the polarizability of one of the colliding pairs of molecules and the quadrupole field of the other. The experimental profiles were analyzed by assuming appropriate line shape functions and using the theoretical matrix elements of the quadrupole moment, isotropic polarizability, and anisotropy of polarizability of the D 2 molecule. From this analysis the characteristic half-width parameters delta/sub q/2 and delta/sub q/4 of the quadrupolar transitions and the binary and ternary absorption coefficients of the S 1 ( J)+S 0 ( J) transitions have been obtained. The experimental value of the binary absorption coefficient of S 1 (0)+S 0 (0) is (2.2 +- 0.1) x 10 -9 cm -1 amagat -2 and the corresponding theoretical value is 1.53 x 10 -9 cm -1 amagat -2

  8. Monogràfic "VI Congrés Internet, Dret i Política. Cloud Computing: El Dret i la Política Pugen al Núvol"

    Directory of Open Access Journals (Sweden)

    Estudis de Dret i Ciència Política

    2011-01-01

    Full Text Available

    L'any 2010 és l'any cloud computing. Així ho afirmen nombrosos analistes i especialistes que veuen que s'expandeixen aplicacions que, en lloc de ser executades a l'ordinador de sobretaula o al portàtil, són hostatjades en un servidor, i a les quals s'accedeix mitjançant un navegador qualsevol. Aquesta expansió és facilitada per la massiva adopció d'ordinadors ultraportàtils i telèfons mòbils intel·ligents, així com per la creixent realitat del teletreball i la col·laboració en xarxa entre administracions, empreses i ciutadans.

    Tenir les dades, els documents de text, els fulls de càlcul, les aplicacions de gestió de clients o d'estocs, i la coordinació de processos i projectes emmagatzemats en servidors de tercers; fer passar les comunicacions personals i professionals per un navegador, o obrir la nostra participació ciutadana a tothom són possibilitats que ens ofereixen noves oportunitats, però també nous reptes sobre com entenem la feina, les relacions professionals o l'exercici de la democràcia.

    Aquests reptes i oportunitats van constituir el punt de trobada de la sisena edició del Congrés Internacional IDP - Internet, Dret i Política, que es va centrar a analitzar i debatre els diferents problemes jurídics i polítics que planteja o pot plantejar la massiva extensió del cloud computing tant a escala professional com personal i ciutadana.

  9. Neoliberalismo y oclusión de la política en el peronismo cordobés. Algunas notas desde una lectura rancièrana

    Directory of Open Access Journals (Sweden)

    Juan Manuel Reynares

    2013-12-01

    Full Text Available Este artículo presenta algunos avances de investigación en el marco de una tesis doctoral que se pregunta por las transformaciones de un actor político – partidario subnacional, el peronismo cordobés, bajo la hegemonía neoliberal en la última década del siglo XX. En pos de una reflexión sobre el neoliberalismo, traemos a colación algunos aportes del filósofo Jacques Rancière, más específicamente su desarrollo de las lógicas de la política y la policía, y de la emergencia subjetiva del demos. Nos interesa analizar algunos efectos de la sobredeterminación neoliberal, tanto en la palabra pública como en la práctica partidaria, en el peronismo cordobés, bajo lo que consideraremos como una expansión de la lógica policial que conlleva una obturación de la posibilidad de emergencia del demos como sujeto político abarcador. Así la práctica política será interpretada por los actores políticos como expresión de diferencias sociales en el aparato administrativo del Estado, o bien como adaptación ante la inevitabilidad de procesos económicos.

  10. GOLD MINERAL PROSPECTING USING PHASED ARRAY TYPE L-BAND SYNTHETIC APERTURE RADAR (PALSAR SATELLITE REMOTE SENSING DATA, CENTRAL GOLD BELT, MALAYSIA

    Directory of Open Access Journals (Sweden)

    A. Beiranvand Pour

    2016-06-01

    Full Text Available The Bentong-Raub Suture Zone (BRSZ of Peninsular Malaysia is one of the significant structural zones in Sundaland, Southeast Asia. It forms the boundary between the Gondwana-derived Sibumasu terrane in the west and Sukhothai arc in the east. The BRSZ is also genetically related to the sediment-hosted/orogenic gold deposits associated with the major lineaments and form-lines in the central gold belt Central Gold Belt of Peninsular Malaysia. In tropical environments, heavy tropical rainforest and intense weathering makes it impossible to map geological structures over long distances. Advances in remote sensing technology allow the application of Synthetic Aperture Radar (SAR data in geological structural analysis for tropical environments. In this investigation, the Phased Array type L-band Synthetic Aperture Radar (PALSAR satellite remote sensing data were used to analyse major geological structures in Peninsular Malaysia and provide detailed characterization of lineaments and form-lines in the BRSZ, as well as its implication for sediment-hosted/orogenic gold exploration in tropical environments. The major geological structure directions of the BRSZ are N-S, NNE-SSW, NE-SW and NW-SE, which derived from directional filtering analysis to PALSAR data. The pervasive array of N-S faults in the study area and surrounding terrain is mainly linked to the N-S trending of the Suture Zone. N-S striking lineaments are often cut by younger NE-SW and NW-SE-trending lineaments. Gold mineralized trends lineaments are associated with the intersection of N-S, NE-SW, NNW-SSE and ESE-WNW faults and curvilinear features in shearing and alteration zones. Lineament analysis on PALSAR satellite remote sensing data is a useful tool for detecting the boundary between the Gondwana-derived terranes and major geological features associated with suture zone especially for large inaccessible regions in tropical environments.

  11. Space Radar Image of Maui, Hawaii

    Science.gov (United States)

    1994-01-01

    This spaceborne radar image shows the 'Valley Island' of Maui, Hawaii. The cloud-penetrating capabilities of radar provide a rare view of many parts of the island, since the higher elevations are frequently shrouded in clouds. The light blue and yellow areas in the lowlands near the center are sugar cane fields. The three major population centers, Lahaina on the left at the western tip of island, Wailuku left of center, and Kihei in the lower center appear as small yellow, white or purple mottled areas. West Maui volcano, in the lower left, is 1800 meters high (5900 feet) and is considered extinct. The entire eastern half of the island consists of East Maui volcano, which rises to an elevation of 3200 meters (10,500 feet) and features a spectacular crater called Haleakala at its summit. Haleakala Crater was produced by erosion during previous ice ages rather than by volcanic activity, although relatively recent small eruptions have produced the numerous volcanic cones and lava flows that can be seen on the floor of the crater. The most recent eruption took place near the coast at the southwestern end of East Maui volcano in the late 1700s. Such a time frame indicates that East Maui should be considered a dormant, rather than an extinct volcano. A new eruption is therefore possible in the next few hundred years. The multi-wavelength capability of the SIR-C radar also permits differences in the vegetation cover on the middle flanks of East Maui to be identified. Rain forests appear in yellow, while grassland is shown in dark green, pink and blue. Radar images such as this one are being used by scientists to understand volcanic processes and to assess potential threats that future activity may pose to local populations. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 16, 1994. The image is 73.7 kilometers by 48.7 kilometers (45.7 miles by 30.2 miles) and is centered at 20

  12. EVALUATION OF AIRBORNE L- BAND MULTI-BASELINE POL-INSAR FOR DEM EXTRACTION BENEATH FOREST CANOPY

    Directory of Open Access Journals (Sweden)

    W. M. Li

    2018-04-01

    Full Text Available DEM beneath forest canopy is difficult to extract with optical stereo pairs, InSAR and Pol-InSAR techniques. Tomographic SAR (TomoSAR based on different penetration and view angles could reflect vertical structure and ground structure. This paper aims at evaluating the possibility of TomoSAR for underlying DEM extraction. Airborne L-band repeat-pass Pol-InSAR collected in BioSAR 2008 campaign was applied to reconstruct the 3D structure of forest. And sum of kronecker product and algebraic synthesis algorithm were used to extract ground structure, and phase linking algorithm was applied to estimate ground phase. Then Goldstein cut-branch approach was used to unwrap the phases and then estimated underlying DEM. The average difference between the extracted underlying DEM and Lidar DEM is about 3.39 m in our test site. And the result indicates that it is possible for underlying DEM estimation with airborne L-band repeat-pass TomoSAR technique.

  13. Evaluation of Airborne l- Band Multi-Baseline Pol-Insar for dem Extraction Beneath Forest Canopy

    Science.gov (United States)

    Li, W. M.; Chen, E. X.; Li, Z. Y.; Jiang, C.; Jia, Y.

    2018-04-01

    DEM beneath forest canopy is difficult to extract with optical stereo pairs, InSAR and Pol-InSAR techniques. Tomographic SAR (TomoSAR) based on different penetration and view angles could reflect vertical structure and ground structure. This paper aims at evaluating the possibility of TomoSAR for underlying DEM extraction. Airborne L-band repeat-pass Pol-InSAR collected in BioSAR 2008 campaign was applied to reconstruct the 3D structure of forest. And sum of kronecker product and algebraic synthesis algorithm were used to extract ground structure, and phase linking algorithm was applied to estimate ground phase. Then Goldstein cut-branch approach was used to unwrap the phases and then estimated underlying DEM. The average difference between the extracted underlying DEM and Lidar DEM is about 3.39 m in our test site. And the result indicates that it is possible for underlying DEM estimation with airborne L-band repeat-pass TomoSAR technique.

  14. Optical properties of oxygen-implanted CdS:O layers in terms of band anticrossing theory

    Energy Technology Data Exchange (ETDEWEB)

    Morozova, N. K., E-mail: MorozovaNK@mail.ru; Kanakhin, A. A.; Miroshnikova, I. N. [Moscow Power Engineering Institute, National Research University (Russian Federation); Galstyan, V. G. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2013-08-15

    The microcathodoluminescence (MCL) and photoreflection spectra of CdS:O layers implanted with oxygen ions to 4 Multiplication-Sign 10{sup 20} cm{sup -3} are investigated. Used method of MCL spectroscopy yields information only about the implanted-layer volume. Exciton MCL spectra, which allow one to determine the concentration of dissolved oxygen in the CdS:O layers and the influence of deviation of the substrates from stoichiometry, are recorded. The homogeneity of the ion-implanted layers is studied by cathodoluminescence (CL) scanning electron microscopy. The relationship between light-emitting areas and the luminescence band at {approx}630 nm is established. The reason for enhancement of this band upon radiation annealing is revealed and its nature as the luminescence of F{sup +} centers in CdS is confirmed. New photoreflection spectroscopy data are obtained, which describe the specific behavioral features of oxygen on the layer surface as an isoelectronic impurity in highly mismatched alloys (HMAs). It is shown that sulfur completely bonds and removes oxygen from CdS:O. Oxygen-free CdS remains on the surface in the form of nanoparticles, the size of which depends on the oxygen concentration in the CdS:O layer bulk. The results obtained are in agreement with the predictions of band anticrossing theory.

  15. Tuning band alignment by CdS layers using a SILAR method to enhance TiO2/CdS/CdSe quantum-dot solar-cell performance.

    Science.gov (United States)

    Zhang, Bingkai; Zheng, Jiaxin; Li, Xiaoning; Fang, Yanyan; Wang, Lin-Wang; Lin, Yuan; Pan, Feng

    2016-04-28

    We report tuning band alignment by optimized CdS layers using a SILAR method to achieve the recorded best performance with about 6% PCE in TiO2/CdS/CdSe QDSSCs. Combining experimental and theoretical studies, we find that a better lattices match between CdS and TiO2 assists the growth of CdSe, and the combined effect of charge transfer and surface dipole moment at the TiO2/CdS/CdSe interface shifts the energy levels of TiO2 upward and increases Voc of the solar cells. More importantly, the band gap of CdS buffer layers is sensitive to the distortion induced by lattice mismatch and numbers of CdS layers. For example, the barrier for charge transfer disappears when there are more than 4 layers of CdS, facilitating the charge injection from CdSe to TiO2.

  16. Observations of copolar correlation coefficient through a bright band at vertical incidence

    Science.gov (United States)

    Zrnic, D. S.; Raghavan, R.; Chandrasekar, V.

    1994-01-01

    This paper discusses an application of polarimetric measurements at vertical incidence. In particular, the correlation coefficients between linear copolar components are examined, and measurements obtained with the National Severe Storms Laboratory (NSSL)'s and National Center for Atmospheric Research (NCAR)'s polarimetric radars are presented. The data are from two well-defined bright bands. A sharp decrease of the correlation coefficient, confined to a height interval of a few hundred meters, marks the bottom of the bright band.

  17. Wide Band and Wide Azimuth Beam Effect on High-resolution Synthetic Aperture Radar Radiometric Calibration

    Directory of Open Access Journals (Sweden)

    Hong Jun

    2015-06-01

    Full Text Available Passive corner reflectors and active transponders are often used as man-made reference targets in Synthetic Aperture Radar (SAR radiometric calibration, With the emergence of new radar systems and the increasing demand for greater accuracy, wide-band and wide-beam radars challenge the hypothesis that the Radar Cross Section (RCS of reference targets is constant. In this study, the FEKO electromagnetic simulation software is used to obtain the change curve of the target RCS as a function of frequency and aspect angle while incorporating high-resolution point-target SAR simulation, and quantitatively analyzing the effect of the modulation effect on SAR images. The simulation results suggest that the abovementioned factors affect the SAR calibration by more than 0.2 dB within a fractional bandwidth greater than 10% or azimuth beam width of more than 20°, which must be corrected in the data processing.

  18. Determination of band alignment in the single-layer MoS2/WSe2 heterojunction

    KAUST Repository

    Chiu, Ming-Hui; Zhang, Chendong; Shiu, Hung-Wei; Chuu, Chih-Piao; Chen, Chang-Hsiao; Chang, Chih-Yuan S.; Chen, Chia-Hao; Chou, Mei-Yin; Shih, Chih-Kang; Li, Lain-Jong

    2015-01-01

    The emergence of two-dimensional electronic materials has stimulated proposals of novel electronic and photonic devices based on the heterostructures of transition metal dichalcogenides. Here we report the determination of band offsets in the heterostructures of transition metal dichalcogenides by using microbeam X-ray photoelectron spectroscopy and scanning tunnelling microscopy/spectroscopy. We determine a type-II alignment between MoS2 and WSe2 with a valence band offset value of 0.83 eV and a conduction band offset of 0.76 eV. First-principles calculations show that in this heterostructure with dissimilar chalcogen atoms, the electronic structures of WSe2 and MoS2 are well retained in their respective layers due to a weak interlayer coupling. Moreover, a valence band offset of 0.94 eV is obtained from density functional theory, consistent with the experimental determination.

  19. Determination of band alignment in the single-layer MoS2/WSe2 heterojunction

    KAUST Repository

    Chiu, Ming-Hui

    2015-07-16

    The emergence of two-dimensional electronic materials has stimulated proposals of novel electronic and photonic devices based on the heterostructures of transition metal dichalcogenides. Here we report the determination of band offsets in the heterostructures of transition metal dichalcogenides by using microbeam X-ray photoelectron spectroscopy and scanning tunnelling microscopy/spectroscopy. We determine a type-II alignment between MoS2 and WSe2 with a valence band offset value of 0.83 eV and a conduction band offset of 0.76 eV. First-principles calculations show that in this heterostructure with dissimilar chalcogen atoms, the electronic structures of WSe2 and MoS2 are well retained in their respective layers due to a weak interlayer coupling. Moreover, a valence band offset of 0.94 eV is obtained from density functional theory, consistent with the experimental determination.

  20. Rainfall Estimation and Performance Characterization Using an X-band Dual-Polarization Radar in the San Francisco Bay Area

    Science.gov (United States)

    Cifelli, R.; Chen, H.; Chandra, C. V.

    2016-12-01

    The San Francisco Bay area is home to over 5 million people. In February 2016, the area also hosted the NFL Super bowl, bringing additional people and focusing national attention to the region. Based on the El Nino forecast, public officials expressed concern for heavy rainfall and flooding with the potential for threats to public safety, costly flood damage to infrastructure, negative impacts to water quality (e.g., combined sewer overflows) and major disruptions in transportation. Mitigation of the negative impacts listed above requires accurate precipitation monitoring (quantitative precipitation estimation-QPE) and prediction (including radar nowcasting). The proximity to terrain and maritime conditions as well as the siting of existing NEXRAD radars are all challenges in providing accurate, short-term near surface rainfall estimates in the Bay area urban region. As part of a collaborative effort between the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, Colorado State University (CSU), and Santa Clara Valley Water District (SCVWD), an X-band dual-polarization radar was deployed in Santa Clara Valley in February of 2016 to provide support for the National Weather Service during the Super Bowl and NOAA's El Nino Rapid Response field campaign. This high-resolution radar was deployed on the roof of one of the buildings at the Penitencia Water Treatment Plant. The main goal was to provide detailed precipitation information for use in weather forecasting and assists the water district in their ability to predict rainfall and streamflow with real-time rainfall data over Santa Clara County especially during a potentially large El Nino year. The following figure shows the radar's coverage map, as well as sample reflectivity observations on March 06, 2016, at 00:04UTC. This paper presents results from a pilot study from February, 2016 to May, 2016 demonstrating the use of X-band weather radar for quantitative precipitation

  1. Development of an S-band cavity Beam Position Monitor for ATF2

    Science.gov (United States)

    Heo, A.; Kim, E.-S.; Kim, H.; Son, D.; Honda, Y.; Tauchi, T.

    2013-04-01

    We have developed an S-band cavity Beam Position Monitor (BPM) in order to measure the position of an electron beam in the final focus area at ATF2, which is the test facility for the final focus design for the International Linear Collider (ILC). The lattice of the ILC Beam Delivery System (BDS) has been modified, requiring a larger physical aperture of 40 mm in the final focus area. The beam orbit measurement in this area is now covered with high resolution S-Band cavity BPMs. In this paper we summarize the design of the cavity BPM and the first experimental results. The calibration slopes were measured as 0.87 counts/μm in the x-coordinate direction and 1.16 counts/μm in the y-coordinate direction.

  2. Single Channel 106 Gbit/s 16QAM Wireless Transmission in the 0.4 THz Band

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Jia, Shi; Ozolins, Oskars

    2017-01-01

    We experimentally demonstrate a single channel 32-GBd 16QAM THz wireless link operating in the 0.4 THz band. Post-FEC net data rate of 106 Gbit/s is successfully achieved without any spatial/frequency multiplexing.......We experimentally demonstrate a single channel 32-GBd 16QAM THz wireless link operating in the 0.4 THz band. Post-FEC net data rate of 106 Gbit/s is successfully achieved without any spatial/frequency multiplexing....

  3. Suppressing band gap of MoS{sub 2} by the incorporation of four- and eight-membered rings

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liyan; Zhang, Tingting, E-mail: ttzhang@hytc.edu.cn [Huaiyin Normal University, School of Physics and Electronic & Electrical Engineering, and Jiangsu Key Laboratory of Modern Measurement Technology and Intelligent Systems (China)

    2015-05-15

    A stable planar allotrope of MoS{sub 2}, formed by introducing four- and eight-membered rings into its hexagonal network (H468), is identified to be a narrow direct-band-gap semiconductor by first principle calculations, which is remarkably different from the large band gap semiconductor of conventional MoS{sub 2} and also the zero band gap allotrope consisting of four- and eight-membered rings (H48) only. The medium-sized direct band gap indicates that H468 would find applications in nanoelectronics and near-infrared optoelectronic devices. Furthermore, the distinctive simulated scanning tunneling microscope images under positive and negative biases might be a unique characteristic for the experimental identification of such an allotrope of MoS{sub 2}.

  4. Bi2Se3/CdS/TiO2 hybrid photoelectrode and its band-edge levels

    International Nuclear Information System (INIS)

    Zhang, Qi; Su, Jun; Zhang, Xianghui; Li, Jian; Zhang, Aiqing; Gao, Yihua

    2012-01-01

    Highlights: ► CVD synthesis of Bi 2 Se 3 nanoparticles. ► Bi 2 Se 3 and CdS co-sensitized TiO 2 nanorod arrays electrode was assembled by CVD. ► Direct physical contact heterojunctions were formed at the interfaces of electrode. ► Cascade structure of band-edge levels was formed in Bi 2 Se 3 /CdS/TiO 2 electrode. - Abstract: Bismuth selenide (Bi 2 Se 3 ) was chosen as the sensitizer to TiO 2 nanorod (NR) arrays photoelectrode to harvest infrared (IR) light for its narrow band gap. For utilizing more amount of IR solar energy, Bi 2 Se 3 nanoparticles (NPs) were grown up to a relative larger grain size. And, a cadmium sulfide (CdS) NPs intermediate layer was introduced to help, to coordinate, the structure of band-edge levels in Bi 2 Se 3 /CdS/TiO 2 electrode. Here, a chemical vapor deposition (CVD) strategy was introduced to assemble this kind of composite photoelectrode. And a cascade structure of band-edge levels constructed in it when achieving electrostatic equilibrium in Na 2 S/Na 2 SO 3 aqueous solution electrolyte revealed by electrochemical analysis method, which will facilitate the hydrogen generation.

  5. An effective 2-band eg model of sulfur hydride H3S for high-Tc superconductivity

    Science.gov (United States)

    Nishiguchi, Kazutaka; Teranishi, Shingo; Miyao, Satoaki; Matsushita, Goh; Kusakabe, Koichi

    To understand high transition temperature (Tc) superconductivity in sulfur hydride H3S, we propose an effective 2-band model having the eg symmetry as the minimal model for H3S. Two eg orbitals centered on a sulfur S atom are chosen for the smallest representation of relevant bands with the van-Hove singularity around the Fermi levels except for the Γ-centered small hole pockets by the sulfur 3 p orbitals. By using the maximally localized Wannier functions, we derive the minimal effective model preserving the body-centered cubic (bcc) crystal symmetry of the H3S phase having the highest Tc ( 203 K under pressures) among the other polymorphs of H3S.

  6. Cognitive Radio Application for Evaluating Coexistence with Cognitive Radars: A Software User’s Guide

    Science.gov (United States)

    2017-10-01

    with both conventional wireless systems as well as other types of cognitive RF systems (e.g., cognitive radar). The radio hardware for this...the base stations are at fixed positions and often elevated and operating with relatively high power compared with mobiles, it is straightforward...for cognitive RF systems to detect the base station’s transmissions and avoid activity that would harm this downlink. By contrast, the mobile

  7. Optical band gap energy and ur bach tail of CdS:Pb2+ thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, M.; Juarez, H.; Pacio, M. [Universidad Autonoma de Puebla, Instituto de Ciencias, Centro de Investigacion en Dispositivos Semiconductores, Av. 14 Sur, Col. Jardines de San Manuel, Ciudad Universitaria, Puebla, Pue. (Mexico); Gutierrez, R.; Chaltel, L.; Zamora, M.; Portillo, O. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, Laboratorio de Materiales, Apdo. Postal 1067, 72001 Puebla, Pue. (Mexico); Mathew, X., E-mail: osporti@yahoo.mx [UNAM, Instituto de Energias Renovables, Temixco, Morelos (Mexico)

    2016-11-01

    Pb S-doped CdS nano materials were successfully synthesized using chemical bath. Transmittance measurements were used to estimate the optical band gap energy. Tailing in the band gap was observed and found to obey Ur bach rule. The diffraction X-ray show that the size of crystallites is in the ∼33 nm to 12 nm range. The peaks belonging to primary phase are identified at 2θ = 26.5 degrees Celsius and 2θ = 26.00 degrees Celsius corresponding to CdS and Pb S respectively. Thus, a shift in maximum intensity peak from 2θ = 26.4 to 28.2 degrees Celsius is clear indication of possible transformation of cubic to hexagonal phase. Also peaks at 2θ = 13.57, 15.9 degrees Celsius correspond to lead perchlorate thiourea. The effects on films thickness and substrate doping on the band gap energy and the width on tail were investigated. Increasing doping give rise to a shift in optical absorption edge ∼0.4 eV. (Author)

  8. Formação da agenda governamental relativa às políticas urbanas no Brasil após a criação do Ministério das Cidades: Uma aplicação do Modelo dos Múltiplos Fluxos

    OpenAIRE

    Menezes, Daiane Boelhouwer; de Souza, Vitoria Gonzatti

    2017-01-01

    Esse texto analisa as políticas de urbanização do país, desde a criação do Ministério das Cidades (MCidades), em 2003, passando pelo Conselho das Cidades (ConCidades), assim como pelo Sistema Nacional de Habitação de Interesse Social (SNHIS) e pelo Fundo Nacional de Habitação de Interesse Social (FNHIS). Para tanto, utiliza-se o modelo dos múltiplos fluxos que tenta explicar de que forma um problema político entra para a agenda governamental e se torna objeto de resolução através de uma polít...

  9. Type-I band alignment at MoS2/In0.15Al0.85N lattice matched heterojunction and realization of MoS2 quantum well

    KAUST Repository

    Tangi, Malleswarara

    2017-08-31

    The valence and conduction band offsets (VBO and CBO) at the semiconductor heterojunction are crucial parameters to design the active region of contemporary electronic and optoelectronic devices. In this report, to study the band alignment parameters at the In0.15Al0.85N/MoS2 lattice matched heterointerface, large area MoS2 single layers are chemical vapor deposited on molecular beam epitaxial grown In0.15Al0.85N films and vice versa. We grew InAlN having an in-plane lattice parameter closely matching with that of MoS2. We confirm that the grown MoS2 is a single layer from optical and structural analyses using micro-Raman spectroscopy and scanning transmission electron microscopy. The band offset parameters VBO and CBO at the In0.15Al0.85N/MoS2 heterojunction are determined to be 2.08 ± 0.15 and 0.60 ± 0.15 eV, respectively, with type-I band alignment using high-resolution x-ray photoelectron spectroscopy in conjunction with ultraviolet photoelectron spectroscopy. Furthermore, we design a MoS2 quantum well structure by growing an In0.15Al0.85N layer on MoS2/In0.15Al0.85N type-I heterostructure. By reducing the nitrogen plasma power and flow rate for the overgrown In0.15Al0.85N layers, we achieve unaltered structural properties and a reasonable preservation of photoluminescence intensity with a peak width of 70 meV for MoS2 quantum well (QW). The investigation provides a pathway towards realizing large area, air-stable, lattice matched, and eventual high efficiency In0.15Al0.85N/MoS2/In0.15Al0.85N QW-based light emitting devices.

  10. Continuously tunable S and C+L bands ultra wideband erbium-doped fiber ring laser

    International Nuclear Information System (INIS)

    Wang, Q; Yu, Q X

    2009-01-01

    This paper presents an ultra wideband tunable silica-based erbium doped fiber ring laser (EDFRL) that can be continuously tuned in S and C+L bands from 1475 to 1619 nm. It is the first time that a fiber ring laser's tuning range reaches 144 nm using a standard silica-based C-band erbium-doped fiber as gain media. In the laser configuration two isolators are used in the fiber loop for suppressing the ASE in C-band and elevating the lasing gain in S-band. As a result the available lasing wavelength is extended toward the shorter wavelength of the gain bandwidth. The optimized erbium-doped fiber length, output coupling ratio and pumping laser power have been obtained through experimental study. This ring fiber laser has simple configuration, low threshold, flat laser spectral distribution and high signal-to-ASE-noise ratio. The laser will have many potential applications in fiber sensor wavelength interrogation, high-resolution spectroscopy and fiber optic communications

  11. O discurso político da agroecologia no MST: O caso do Assentamento 17 de Abril em Eldorado dos Carajás, Pará

    Directory of Open Access Journals (Sweden)

    Caetano De’ Carli

    2013-10-01

    Full Text Available O presente artigo visa debater a agroecologia enquanto discurso político. Parte‑se das pesquisas de Altieri, Nichols, Gliessman, Gúzman, Cristoffoli, entre outros autores, para evidenciar as trajetórias da agroecologia enquanto ciência e as tentativas da sua materialização em áreas da reforma agrária. Após essas perspectivas, aborda‑se a agroecologia na prática política do Movimento dos Trabalhadores Rurais Sem‑Terra, tanto no que se refere às suas experiências‑modelos como ao discurso político que assume, em contraposição com o modelo hegemônico da Revolução Verde. Por fim, debruça‑se sobre o caso do Assentamento 17 de Abril em Eldorado dos Carajás, ressaltando como esse discurso político representa uma importante estratégia do MST em relação a uma mudança de paradigma na mentalidade dos assentados e das lideranças locais do movimento, destacando ser esse um importante passo para a materialização de produções agropecuárias alternativas nas áreas de reforma agrária no Brasil.

  12. Gobernar a otros y gobernarse a sí mismo según la razón política liberal

    Directory of Open Access Journals (Sweden)

    Carlos Frade

    2007-01-01

    Full Text Available Este artículo intenta analizar la razón política liberal en sus dos arenas de despliegue privilegiadas: la relación de empleo en lo que concierne a gobernar a otros y la agencia empresarial en lo que concierne a gobernarse a sí mismo. Propone un marco teórico para abordar la razón política liberal como razón gubernamental, a la vez que trata de ilustrarlo mediante algunos análisis y estudios empíricos concretos. El artículo parte de una lectura crítica de Foucault y los estudios de gubernamentalidad y, en esencia, aspira a mostrar el doble imperativo, normalmente no reconocido, en que se fundamenta el liberalismo, consistente en aumentar la exposición de individuos y poblaciones al mercado y en someter ambos a la disciplina y a los controles cada vez más férreos que tal exposición inevitablemente conlleva. En particular, se muestra cómo la norma de empleo ha sido debilitada, y en parte sustituida, por un modelo de sujeto y de comportamiento impulsado por las políticas de empleabilidad y activación, mientras que las grandes empresas y los negocios tienden cada vez más a convertirse en puros modos de agencia revestidos de formas organizacionales cambiables y capaces de sustraerse a la inscripción legal, a la trazabilidad estadística y, en general, al control del Estado.

  13. ¡No más niños! Análisis y balance de la política china del hijo único treinta años después de su implantación.

    OpenAIRE

    Gomà, Daniel

    2011-01-01

    El control de la sobrepoblación ha sido uno de los principales quebraderos de cabeza de los gobernantes de China de los últimos sesenta años. Las políticas dirigidas a controlar el crecimiento de la población no han estado exentas de polémicas, al igual que los resultados obtenidos. Considerada la medida más coercitiva en materia de control demográfico, la política del Hijo Único ha cambiado la conducta reproductiva de la población china a lo largo de las últimas tres décadas y ha tenido impo...

  14. La teoría de la política internacional treinta años después

    Directory of Open Access Journals (Sweden)

    Leire Moure

    2009-01-01

    Full Text Available En 2009 la Teoría de la Política Internacional de K. N. Waltz ha cumplido treinta años. Es indudable que la escena internacional ha cambiado sustancialmente desde la publicación de su obra cumbre. La Guerra Fría, que a finales de los setenta la convirtió en marco explicativo destacado de la realidad internacional de la época, se desvaneció a comienzos de los noventa del siglo pasado. El mundo bipolar caracterizado por la intensa rivalidad entre los Estados Unidos y la Unión Soviética dio paso a un escenario definido por el vencedor de la carrera de fondo que se había inaugurado con el final de la Segunda Guerra Mundial. El previsible mundo de la etapa bipolar había dado paso a un entorno unipolar cada vez más complejo y el nuevo siglo trajo nuevas amenazas para la seguridad no previstas por la vieja teoría realista. Sin duda, el sistema internacional actual es bien distinto al que acogió con éxito a la Teoría de la Política Internacional. Ante estas nuevas circunstancias,la propuesta teórica de Waltz ha encontrado un acomodo explicativo cada vez más problemático.No cabe duda que la obra de Waltz transformó la teoría de las Relaciones Internacionales del último cuarto del siglo XX y su impacto ha sido excepcional en la disciplina. En fechas recientes J. J. Mearsheimer recordaba que “casi todo el mundo en nuestro área de conocimiento ha respondido a Waltz de una u otra manera”. Esta circunstancia le ha convertido en “el líder por excelencia del pensamiento teórico en las Relaciones Internacionales de los últimos cinco lustros” y en “la influencia más importante para todos los realistas actuales, —y para muchos no realistas—, con menos de sesenta años”. Prueba de ello es la profunda conexión del neoliberalismo con las aportaciones del autor. R. O. Keohane da cuenta explícitamente de esta relación al afirmar que “la teoría institucional supone un desafío desde principios de los ochenta al realismo

  15. Estimation of surface roughness in a semiarid region from C-band ERS-1 synthetic aperture radar data

    Directory of Open Access Journals (Sweden)

    E. E. Sano

    1999-12-01

    Full Text Available In this study, we investigated the feasibility of using the C-band European Remote Sensing Satellite (ERS-1 synthetic aperture radar (SAR data to estimate surface soil roughness in a semiarid rangeland. Radar backscattering coefficients were extracted from a dry and a wet season SAR image and were compared with 47 in situ soil roughness measurements obtained in the rocky soils of the Walnut Gulch Experimental Watershed, southeastern Arizona, USA. Both the dry and the wet season SAR data showed exponential relationships with root mean square (RMS height measurements. The dry C-band ERS-1 SAR data were strongly correlated (R² = 0.80, while the wet season SAR data have somewhat higher secondary variation (R² = 0.59. This lower correlation was probably provoked by the stronger influence of soil moisture, which may not be negligible in the wet season SAR data. We concluded that the single configuration C-band SAR data is useful to estimate surface roughness of rocky soils in a semiarid rangeland.

  16. Fútbol y política Reflexiones de una relación compleja a través del festival de cine Thinking Football

    OpenAIRE

    Pulleiro Méndez, Carlos

    2015-01-01

    En el presente artículo se van a analizar las complejas y discutidas relaciones entre el fútbol y la política a través de lo que sugieren algunas de las películas que se han mostrado en el festival de cine Thinking Football de 2015. En ellas se refleja a la perfección la multiplicidad de actores políticos del fútbol, lo cual dará pie a considerar si este deporte y su máxima autoridad, la FIFA, tienen un compromiso político propio. Artículo revisado por pares

  17. La defensa de presos políticos a comienzos de los ´70: ejercicio profesional, derecho y política A defesa dos presos políticos no início dos anos 70: a prática profissional, o direito ea política The defense of political prisoners in the early '70s: professional practice, law and politics

    OpenAIRE

    Mauricio Chama

    2010-01-01

    El trabajo aborda la relación entre abogacía y política a comienzos de la década del '70. Más precisamente se propone identificar y reconstruir los principales rasgos que asume la defensa de presos políticos en ese período. Más que una labor específica, se entiende que la defensa de presos políticos en esos años representó una novedosa configuración que logró articular una nueva asociación de profesionales del derecho, renovadas estrategias de defensa, una vasta y sistemática labor de denunci...

  18. Band alignment of two-dimensional metal monochalcogenides MXs (M=Ga,In; X=S,Se,Te

    Directory of Open Access Journals (Sweden)

    Huazheng Sun

    2017-09-01

    Full Text Available Monolayer metal monochalcogenides MXs (M=Ga,In; X=S,Se,Te form a new class of two-dimensional semiconductors with indirect band gaps, and their band alignment information is investigated via first principles calculations. The dependence of band gap, valence-band maximum, conduction band minimum, and charge transfer on the M or X element has been obtained and can be understood from the orbital analysis of the band edges. Potential applications of metal monochalcogenides to design van der Waals heterostructures and catalyse the photo-splitting reaction of water have been discussed.

  19. Radar Search and Detection With the CASA 212 S43 Aircraft

    National Research Council Canada - National Science Library

    Borges, Jose M

    2004-01-01

    .... The model can use given periscope radar cross section data, or roughly calculate radar cross section given assumptions about exposed periscope height above the sea-surface and sea-state conditions. Submarine evasion due to radar counter-detection is also modeled.

  20. Evaluation of X-band polarimetric radar estimation of rainfall and rain drop size distribution parameters in West Africa

    Science.gov (United States)

    Koffi, A. K.; Gosset, M.; Zahiri, E.-P.; Ochou, A. D.; Kacou, M.; Cazenave, F.; Assamoi, P.

    2014-06-01

    As part of the African Monsoon Multidisciplinary Analysis (AMMA) field campaign an X-band dual-polarization Doppler radar was deployed in Benin, West-Africa, in 2006 and 2007, together with a reinforced rain gauge network and several optical disdrometers. Based on this data set, a comparative study of several rainfall estimators that use X-band polarimetric radar data is presented. In tropical convective systems as encountered in Benin, microwave attenuation by rain is significant and quantitative precipitation estimation (QPE) at X-band is a challenge. Here, several algorithms based on the combined use of reflectivity, differential reflectivity and differential phase shift are evaluated against rain gauges and disdrometers. Four rainfall estimators were tested on twelve rainy events: the use of attenuation corrected reflectivity only (estimator R(ZH)), the use of the specific phase shift only R(KDP), the combination of specific phase shift and differential reflectivity R(KDP,ZDR) and an estimator that uses three radar parameters R(ZH,ZDR,KDP). The coefficients of the power law relationships between rain rate and radar variables were adjusted either based on disdrometer data and simulation, or on radar-gauges observations. The three polarimetric based algorithms with coefficients predetermined on observations outperform the R(ZH) estimator for rain rates above 10 mm/h which explain most of the rainfall in the studied region. For the highest rain rates (above 30 mm/h) R(KDP) shows even better scores, and given its performances and its simplicity of implementation, is recommended. The radar based retrieval of two parameters of the rain drop size distribution, the normalized intercept parameter NW and the volumetric median diameter Dm was evaluated on four rainy days thanks to disdrometers. The frequency distributions of the two parameters retrieved by the radar are very close to those observed with the disdrometer. NW retrieval based on a combination of ZH

  1. Initial assessment of an airborne Ku-band polarimetric SAR.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2013-02-01

    Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940s. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analysts understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band for airborne or unmanned aerial systems.

  2. Characterization of hydrometeors in Sahelian convective systems with an X-band radar and comparison with in situ measurements. Part I : Sensitivity of polarimetric radar particle identification retrieval and case study evaluation

    OpenAIRE

    Cazenave, Frédéric; Gosset, Marielle; Kacou, M.; Alcoba, M.; Fontaine, E.; Duroure, C.; Dolan, B.

    2016-01-01

    The particle identification scheme developed by Dolan and Rutledge for X-band polarimetric radar is tested for the first time in Africa and compared with in situ measurements. The data were acquired during the Megha-Tropiques mission algorithm-validation campaign that occurred in Niger in 2010. The radar classification is compared with the in situ observations gathered by an instrumented aircraft for the 13 August 2010 squall-line case. An original approach has been developed for the radar-in...

  3. 16O+16O molecular nature of the superdeformed band of 32S and the evolution of the molecular structure

    International Nuclear Information System (INIS)

    Kimura, Masaaki; Horiuchi, Hisashi

    2004-01-01

    The relation between the superdeformed band of 32 S and 16 O+ 16 O molecular bands is studied by the deformed-basis antisymmetrized molecular dynamics with the Gogny D1S force. It is found that the obtained superdeformed band members of S have a considerable amount of the 16 O+ 16 O component. Above the superdeformed band, we have obtained two excited rotational bands which have more prominent character of the 16 O+ 16 O molecular band. These three rotational bands are regarded as a series of 16 O+ 16 O molecular bands which were predicted by using the unique 16 O- 16 O optical potential. As the excitation energy and principal quantum number of the relative motion increase, the 16 O+ 16 O cluster structure becomes more prominent but at the same time, the band members are fragmented into several states

  4. The InSAeS4 Airborne X-Band Interferometric SAR System: A First Assessment on Its Imaging and Topographic Mapping Capabilities

    Directory of Open Access Journals (Sweden)

    Stefano Perna

    2016-01-01

    Full Text Available We present in this work a first assessment of the imaging and topographic mapping capabilities of the InSAeS4 system, which is a single-pass interferometric airborne X-Band Synthetic Aperture Radar (SAR. In particular, we first provide a brief description of the InSAeS4 sensor. Then, we discuss the results of our analysis on the SAR and interferometric SAR products relevant to the first flight-test campaign. More specifically, we have exploited as reference the GPS measurements relevant to nine Corner Reflectors (CRs deployed over the illuminated area during the campaign and a laser scanner Digital Elevation Model (DEM. From the analysis carried out on the CRs we achieved a mean geometric resolution, for the SAR products, of about 0.14 m in azimuth and 0.49 m in range, a positioning misalignment with standard deviation of 0.07 m in range and 0.08 m in azimuth, and a height error with standard deviation of 0.51 m. From the comparison with the laser scanner DEM we estimated a height error with standard deviation of 1.57 m.

  5. Radar Image, Hokkaido, Japan

    Science.gov (United States)

    2000-01-01

    The southeast part of the island of Hokkaido, Japan, is an area dominated by volcanoes and volcanic caldera. The active Usu Volcano is at the lower right edge of the circular Lake Toya-Ko and near the center of the image. The prominent cone above and to the left of the lake is Yotei Volcano with its summit crater. The city of Sapporo lies at the base of the mountains at the top of the image and the town of Yoichi -- the hometown of SRTM astronaut Mamoru Mohri -- is at the upper left edge. The bay of Uchiura-Wan takes up the lower center of the image. In this image, color represents elevation, from blue at the lowest elevations to white at the highest. The radar image has been overlaid to provide more details of the terrain. Due to a processing problem, an island in the center of this crater lake is missing and will be properly placed when further SRTM swaths are processed. The horizontal banding in this image is a processing artifact that will be removed when the navigation information collected by SRTM is fully calibrated. This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 100 by 150 kilometers (62

  6. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  7. Meteorite Falls Observed in U.S. Weather Radar Data in 2015 and 2016 (To Date)

    Science.gov (United States)

    Fries, Marc; Fries, Jeffrey; Hankey, Mike; Matson, Robert

    2016-01-01

    To date, over twenty meteorite falls have been located in the weather radar imagery of the National Oceanic and Atmospheric Administration (NOAA)'s NEXRAD radar network. We present here the most prominent events recorded since the last Meteoritical Society meeting, covering most of 2015 and early 2016. Meteorite Falls: The following events produced evidence of falling meteorites in radar imagery and resulted in meteorites recovered at the fall site. Creston, CA (24 Oct 2015 0531 UTC): This event generated 218 eyewitness reports submitted to the American Meteor Society (AMS) and is recorded as event #2635 for 2015 on the AMS website. Witnesses reported a bright fireball with fragmentation terminating near the city of Creston, CA, north of Los Angeles. Sonic booms and electrophonic noise were reported in the vicinity of the event. Weather radar imagery records signatures consistent with falling meteorites in data from the KMUX, KVTX, KHNX and KVBX. The Meteoritical Society records the Creston fall as an L6 meteorite with a total recovered mass of 688g. Osceola, FL (24 Jan 2016 1527 UTC): This daytime fireball generated 134 eyewitness reports on AMS report number 266 for 2016, with one credible sonic boom report. The fireball traveled roughly NE to SW with a terminus location north of Lake City, FL in sparsely populated, forested countryside. Radar imagery shows distinct and prominent evidence of a significant meteorite fall with radar signatures seen in data from the KJAX and KVAX radars. Searchers at the fall site found that recoveries were restricted to road sites by the difficult terrain, and yet several meteorites were recovered. Evidence indicates that this was a relatively large meteorite fall where most of the meteorites are unrecoverable due to terrain. Osceola is an L6 meteorite with 991 g total mass recovered to date. Mount Blanco, TX (18 Feb 2016 0343 UTC): This event produced only 39 eyewitness reports and is recorded as AMS event #635 for 2016. No

  8. What is the band alignment of Cu2ZnSn(S,Se)4 solar cells?

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Hansen, Ole

    2017-01-01

    The band alignment at the Cu2ZnSn(S,Se)4/CdS solar cell heterojunction is a controversial issue, as different measurements and calculations point to substantially different conduction band offsets (CBO). As the actual value of the CBO has profound implications on solar cell performance, the aim...... of this work is to separate genuine process-dependent variations in the CBO from errors in its experimental determination. We argue that the two most likely mechanisms responsible for real CBO variations are Fermi level pinning (which tends to decrease the CBO) and chemical interdiffusion (which tends...... measurement approaches. Interestingly, a rough correlation can be established between the CBO measured at the Cu2ZnSnS4/CdS interface by different groups and their corresponding solar cell efficiency: lower-efficiency cells often have a large "cliff-like" offset, whereas most high-efficiency cells have...

  9. 160 Gbit/s photonics wireless transmission in the 300-500 GHz band

    Directory of Open Access Journals (Sweden)

    X. Yu

    2016-11-01

    Full Text Available To accommodate the ever increasing wireless traffic in the access networks, considerable efforts have been recently invested in developing photonics-assisted wireless communication systems with very high data rates. Superior to photonic millimeter-wave systems, terahertz (THz band (300 GHz-10 THz provides a much larger bandwidth and thus promises an extremely high capacity. However, the capacity potential of THz wireless systems has by no means been achieved yet. Here, we successfully demonstrate 160 Gbit/s wireless transmission by using a single THz emitter and modulating 25 GHz spaced 8 channels (20 Gbps per channel in the 300-500 GHz band, which is the highest bitrate in the frequency band above 300 GHz, to the best of our knowledge.

  10. Resolution of the 179W-isomer anomaly: Exposure of a Fermi-aligned s band

    International Nuclear Information System (INIS)

    Walker, P.M.; Dracoulis, G.D.; Byrne, A.P.; Fabricius, B.; Kibedi, T.; Stuchbery, A.E.; Department of Physics, University of Surrey, Guildford, GU2 5XH United Kingdom)

    1991-01-01

    The K π =35/2 - , five-quasiparticle isomer in 179 W is shown to decay into the region of a backbend in the 7/2 - [514] band, allowing for the first time the identification of a full set of aligned-band states. Destructive interference results from level mixing in the band-crossing region. The deduced γ-ray branching ratios are used to establish the mixing matrix elements and to show that the aligned band has a high value of the K quantum number. The properties of well-defined alignment and yet also high K provide the first clear example of a Fermi-aligned s band. The anomalous decay of the isomer itself is now explained

  11. Entre a política e o prazer: ditadura, arte e boêmia através do filme Garota de Ipanema (Leon Hirszman, 1967 = Between politics and pleasure: dictatorship, art and bohemia throughout Leon Hirszman’s Garota de Ipanema (1967 = Entre la política y el placer: dictadura, arte y bohemia a través del film Garota de Ipanema (Leon Hirszman, 1967

    Directory of Open Access Journals (Sweden)

    Pinto, Carlos Eduardo Pinto de

    2017-01-01

    Full Text Available O artigo aborda, através da análise do filme Garota de Ipanema (Leon Hirszman, 1967 e de seu circuito social, as tensões entre política e prazer no cotidiano do Rio de Janeiro durante a ditadura militar. A releitura de uma canção da Bossa Nova através de um filme que pretendia acompanhar o cotidiano de uma menina de classe média em Ipanema é esperada como um rompimento com os pressupostos do cinema político seguidos até então por seu diretor, um dos expoentes do Cinema Novo brasileiro. Afinal, tanto a Bossa quanto Ipanema eram consideradas metonímias de uma boêmia despolitizada que não se conectava, aparentemente, com a proposta de intervenção da arte na sociedade, seguida pelos cinemanovistas. Ironicamente, o filme decepcionou a crítica, justamente por não ser um bom entretenimento, se propondo a compreender a inserção da protagonista no mundo, inclusive sua relação com a política sob uma ditadura. Desse modo, a análise possibilita pensar as conexões entre ditadura, arte e boêmia no filme e através dele

  12. Forest biomass, canopy structure, and species composition relationships with multipolarization L-band synthetic aperture radar data

    Science.gov (United States)

    Sader, Steven A.

    1987-01-01

    The effect of forest biomass, canopy structure, and species composition on L-band synthetic aperature radar data at 44 southern Mississippi bottomland hardwood and pine-hardwood forest sites was investigated. Cross-polarization mean digital values for pine forests were significantly correlated with green weight biomass and stand structure. Multiple linear regression with five forest structure variables provided a better integrated measure of canopy roughness and produced highly significant correlation coefficients for hardwood forests using HV/VV ratio only. Differences in biomass levels and canopy structure, including branching patterns and vertical canopy stratification, were important sources of volume scatter affecting multipolarization radar data. Standardized correction techniques and calibration of aircraft data, in addition to development of canopy models, are recommended for future investigations of forest biomass and structure using synthetic aperture radar.

  13. Earth-Space Link Attenuation Estimation via Ground Radar Kdp

    Science.gov (United States)

    Bolen, Steven M.; Benjamin, Andrew L.; Chandrasekar, V.

    2003-01-01

    A method of predicting attenuation on microwave Earth/spacecraft communication links, over wide areas and under various atmospheric conditions, has been developed. In the area around the ground station locations, a nearly horizontally aimed polarimetric S-band ground radar measures the specific differential phase (Kdp) along the Earth-space path. The specific attenuation along a path of interest is then computed by use of a theoretical model of the relationship between the measured S-band specific differential phase and the specific attenuation at the frequency to be used on the communication link. The model includes effects of rain, wet ice, and other forms of precipitation. The attenuation on the path of interest is then computed by integrating the specific attenuation over the length of the path. This method can be used to determine statistics of signal degradation on Earth/spacecraft communication links. It can also be used to obtain real-time estimates of attenuation along multiple Earth/spacecraft links that are parts of a communication network operating within the radar coverage area, thereby enabling better management of the network through appropriate dynamic routing along the best combination of links.

  14. Efficient evaluation of epitaxial MoS2 on sapphire by direct band structure imaging

    Science.gov (United States)

    Kim, Hokwon; Dumcenco, Dumitru; Fregnaux, Mathieu; Benayad, Anass; Kung, Yen-Cheng; Kis, Andras; Renault, Olivier; Lanes Group, Epfl Team; Leti, Cea Team

    The electronic band structure evaluation of two-dimensional metal dichalcogenides is critical as the band structure can be greatly influenced by the film thickness, strain, and substrate. Here, we performed a direct measurement of the band structure of as-grown monolayer MoS2 on single crystalline sapphire by reciprocal-space photoelectron emission microscopy with a conventional laboratory ultra-violet He I light source. Arrays of gold electrodes were deposited onto the sample in order to avoid charging effects due to the insulating substrate. This allowed the high resolution mapping (ΔE = 0.2 eV Δk = 0.05 Å-1) of the valence states in momentum space down to 7 eV below the Fermi level. The high degree of the epitaxial alignment of the single crystalline MoS2 nuclei was verified by the direct momentum space imaging over a large area containing multiple nuclei. The derived values of the hole effective mass were 2.41 +/-0.05 m0 and 0.81 +/-0.05 m0, respectively at Γ and K points, consistent with the theoretical values of the freestanding monolayer MoS2 reported in the literature. HK acknowledges the french CEA Basic Technological Research program (RTB) for funding.

  15. O 18 Brumário, política e pós-modernismo The Eighteenth Brumaire, politics and postmodernism

    Directory of Open Access Journals (Sweden)

    Adriano Nervo Codato

    2005-04-01

    Full Text Available A maioria das interpretações contemporâneas das análises de Karl Marx sobre a política européia da segunda metade do século XIX têm, em comum, a supressão de toda menção à "economia" e sua substituição, ou pela autonomia da política, nas versões heterodoxas, ou pelo caráter performativo da linguagem, nas versões pós-modernas. Neste artigo, sustenta-se que há n'O 18 Brumário de Luís Bonaparte uma interpretação da política que pode ser reduzida, do ponto de vista teórico, a dois princípios explicativos da concepção materialista da história: a primazia do econômico e a oposição entre essência e aparência. O artigo se propõe a verificar a incidência desses postulados naquele texto.Most contemporary interpretations of Karl Marx's analyses of European politics of the second half of the nineteenth century share both the suppression of all references to the "economy" and its substitution either for the idea of the autonomy of the political (in heterodox views, or for the idea of the performative aspect of language (in post-modern views. This article argues that Marx's Eighteenth Brumaire of Louis Bonapart contains an interpretation of politics that can be reduced, from the theoretical point of view, to two explanatory principles of the materialist conception of history: the primacy of economics, and the opposition between essence and appearance. The article seeks to verify the incidence of these two fundamental propositions within that text.

  16. 640 Gbit/s Optical Packet Switching using a Novel In-Band Optical Notch-Filter Labeling Scheme

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros; Galili, Michael; Oxenløwe, Leif Katsuo

    2014-01-01

    Optical packet switching of 640 Gbit/s data packets is reported using an in-band optical labeling technique based on notch-filtering of the data spectrum and extracting the label using a bandpass filter. BER 10􀀀9 is achieved.......Optical packet switching of 640 Gbit/s data packets is reported using an in-band optical labeling technique based on notch-filtering of the data spectrum and extracting the label using a bandpass filter. BER 10􀀀9 is achieved....

  17. Study of sea-surface slope distribution and its effect on radar backscatter based on Global Precipitation Measurement Ku-band precipitation radar measurements

    Science.gov (United States)

    Yan, Qiushuang; Zhang, Jie; Fan, Chenqing; Wang, Jing; Meng, Junmin

    2018-01-01

    The collocated normalized radar backscattering cross-section measurements from the Global Precipitation Measurement (GPM) Ku-band precipitation radar (KuPR) and the winds from the moored buoys are used to study the effect of different sea-surface slope probability density functions (PDFs), including the Gaussian PDF, the Gram-Charlier PDF, and the Liu PDF, on the geometrical optics (GO) model predictions of the radar backscatter at low incidence angles (0 deg to 18 deg) at different sea states. First, the peakedness coefficient in the Liu distribution is determined using the collocations at the normal incidence angle, and the results indicate that the peakedness coefficient is a nonlinear function of the wind speed. Then, the performance of the modified Liu distribution, i.e., Liu distribution using the obtained peakedness coefficient estimate; the Gaussian distribution; and the Gram-Charlier distribution is analyzed. The results show that the GO model predictions with the modified Liu distribution agree best with the KuPR measurements, followed by the predictions with the Gaussian distribution, while the predictions with the Gram-Charlier distribution have larger differences as the total or the slick filtered, not the radar filtered, probability density is included in the distribution. The best-performing distribution changes with incidence angle and changes with wind speed.

  18. Grain size and lattice parameter's influence on band gap of SnS thin nano-crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Yashika [Department of Electronics, S.G.T.B. Khalsa College, University of Delhi, Delhi 110007 (India); Department of Electronic Science, University of Delhi-South Campus, New Delhi 110021 (India); Arun, P., E-mail: arunp92@physics.du.ac.in [Department of Electronics, S.G.T.B. Khalsa College, University of Delhi, Delhi 110007 (India); Naudi, A.A.; Walz, M.V. [Facultad de Ingeniería, Universidad Nacional de Entre Ríos, 3101 Oro Verde (Argentina); Albanesi, E.A. [Facultad de Ingeniería, Universidad Nacional de Entre Ríos, 3101 Oro Verde (Argentina); Instituto de Física del Litoral (CONICET-UNL), Guemes 3450, 3000 Santa Fe (Argentina)

    2016-08-01

    Tin sulphide nano-crystalline thin films were fabricated on glass and Indium Tin Oxide (ITO) substrates by thermal evaporation method. The crystal structure orientation of the films was found to be dependent on the substrate. Residual stress existed in the films due to these orientations. This stress led to variation in lattice parameter. The nano-crystalline grain size was also found to vary with film thickness. A plot of band-gap with grain size or with lattice parameter showed the existence of a family of curves. This implied that band-gap of SnS films in the preview of the present study depends on two parameters, lattice parameter and grain size. The band-gap relation with grain size is well known in the nano regime. Experimental data fitted well with this relation for the given lattice constants. The manuscript uses theoretical structure calculations for different lattice constants and shows that the experimental data follows the trend. Thus, confirming that the band gap has a two variable dependency. - Highlights: • Tin sulphide films are grown on glass and ITO substrates. • Both substrates give differently oriented films. • The band-gap is found to depend on grain size and lattice parameter. • Using data from literature, E{sub g} is shown to be two parameter function. • Theoretical structure calculations are used to verify results.

  19. Type-I band alignment at MoS2/In0.15Al0.85N lattice matched heterojunction and realization of MoS2 quantum well

    KAUST Repository

    Tangi, Malleswararao; Mishra, Pawan; Li, Ming-Yang; Shakfa, Mohammad Khaled; Anjum, Dalaver H.; Hedhili, Mohamed N.; Ng, Tien Khee; Li, Lain-Jong; Ooi, Boon S.

    2017-01-01

    matching with that of MoS2. We confirm that the grown MoS2 is a single layer from optical and structural analyses using micro-Raman spectroscopy and scanning transmission electron microscopy. The band offset parameters VBO and CBO at the In0.15Al0.85N/MoS2

  20. Resolution of the 179W isomer anomaly: exposure of a fermi aligned s-band

    International Nuclear Information System (INIS)

    Walker, P.M.; Surrey Univ., Guildford; Dracoulis, G.D.; Byrne, A.P.; Fabricius, B.; Kibedi, T.; Stuchbery, A.E.

    1991-06-01

    The K Π = 35/2 - , five quasiparticle isomer in 179 W is shown to decay into the region of a backbend in the 7/2 - [514] band, allowing for the first time the identification of a full set of aligned-band states. Destructive interference results from level-mixing in the band-crossing region. The deduced γ-ray branching ratios are used to establish the mixing matrix elements and to show that the aligned band has a high value of the K-quantum number. The properties of well-defined alignment and yet also high-K, provided the first clear example of a Fermi Aligned s-band. The anomalous decay of the isomer itself is now explained. 11 refs., 1 tab., 3 figs

  1. Beam Dynamics a Integrated Plane Wave Transformer Photoinjector at S- and X- band

    Science.gov (United States)

    Rosenzweig, J. B.; Ding, X.; Pellegrini, X.; Serafini, L.; Yu, D.

    1997-05-01

    The beam dynamics of an integrated S-band rf photoinjector based on the plane wave transformer concept, proposed as part of an SBIR collaboration between UCLA and DULY Research, are studied. The intial design, which calls for an 11.5 cell structure run at a peak on-axis accelerating field of 60 MV/m, and has a compact solenoid around the intial 2.5 cells, is based on the recently developed theory of emittance compensation(L.Serafini, and J.B. Rosenzweig, submitted to Physical Review E.). It calls for matching the beam onto an envelope which is a generalized Brillouin flow, producing a beam which diminishes in transverse size as the square root of the accelerating beam energy. This condition produces a minimized emittance, which for the S-band case is 1 mm-rad at at charge of 1 nC. This design is also scaled to produce nearly identical performance at X-band, giving an injector appropriate to running an FEL at the SLAC NLCTA. It is noted that these designs are insensitive to rf emittance increase, allowign a choice of injection phase, and the option to compress the emitted pulse.

  2. CdS_xTe_1_-_x ternary semiconductors band gaps calculation using ground state and GW approximations

    International Nuclear Information System (INIS)

    Kheloufi, Nawal; Bouzid, Abderrazak

    2016-01-01

    We present band gap calculations of zinc-blende ternary CdS_xTe_1_-_x semiconductors within the standard DFT and quasiparticle calculations employing pseudopotential method. The DFT, the local density approximation (LDA) and the Generalized Gradient Approximation (GGA) based calculations have given very poor results compared to experimental data. The quasiparticle calculations have been investigated via the one-shot GW approximation. The present paper discuses and confirms the effect of inclusion of the semicore states in the cadmium (Cd) pseudopotential. The obtained GW quasiparticle band gap using Cd"+"2"0 pseudopotential has been improved compared to the obtained results from the available pseudopotential without the treatment of semicore states. Our DFT and quasiparticle band gap results are discussed and compared to the available theoretical calculations and experimental data. - Graphical abstract: Band gaps improvement concerning the binary and ternary alloys using the GW approximation and Cd"2"0"+ pseudopotential with others levels of approximations (the LDA and GGA approximation employing the Cd"1"2"+ and the LDA within Cd"2"0"+ pseudopotential). - Highlights: • The direct Γ- Γ and indirect Γ- X and Γ- L bands gaps show a nonlinear behavior when S content is enhanced. • The quasiparticle band gap result for the investigated semiconductors is improved using the GW approximation. • All CdS_xTe_1_-_x compounds in all compositions range from 0 to 1 are direct band gap semiconductors.

  3. Leerse a sí mismo: hermenéutica, política y retórica en Thomas Hobbes

    Directory of Open Access Journals (Sweden)

    María José Rossi

    2014-11-01

    Full Text Available El reconocimiento del conflicto como realidad constitutiva de lo humano y la necesidad de un cierre que pasa por la fijación de la palabra justa encuentran en Hobbes su primera formulación. El pasaje de la instancia retórico-interpretativa a la axiomático-científica se da en Leviatan a través de tres momentos: introspectivo, contractual, estadual; su despliegue permite reconocer a la hermenéutica como resorte imprescindible para la implantación de un orden político fundado en la articulación entre ser (una antropología, decir (una retórica y actuar (una praxis. El intérprete resulta así un operador clave en el ajuste de las instancias natural y político-social

  4. IHEP S-band 45 MW pulse power klystron development

    International Nuclear Information System (INIS)

    Dong Dong; Zhou Zusheng; Zhang Liang; Li Gangying; Tian Shuangmin

    2006-01-01

    S-band 45 MW pulse power klystron has been developed in the Institute of High Energy Physics (IHEP) for the Beijing Electron Positron Collider (BEPC) upgrade projects (BEPC-II). This new klystron has 5 cavities in its RF-beam interaction and single RF output window, and the RF output power is 45 MW at 310 kV, the gain is 50 dB, the efficiency 40%. The manufacturing, training and testing of a prototype klystron has been finished in IHEP and RF power 45 MW at 300 kV has been reached. The testing results show that all the parameters of the 45 MW klystron reach the design goal. (authors)

  5. GPM GROUND VALIDATION NOAA S-BAND PROFILER MINUTE DATA MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NOAA S-Band Profiler Minute Data MC3E dataset was gathered during the Midlatitude Continental Convective Clouds Experiment (MC3E) in...

  6. Coastal flood inundation monitoring with Satellite C-band and L-band Synthetic Aperture Radar data

    Science.gov (United States)

    Ramsey, Elijah W.; Rangoonwala, Amina; Bannister, Terri

    2013-01-01

    Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm- and tidal-related flooding of spatially extensive coastal marshes within the north-central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L-Band SAR (PALSAR) (L-band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C-band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006-2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR- and ASAR-based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference-scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR-based inundation accuracies averaged 84% (n = 160), while ASAR-based mapping accuracies averaged 62% (n = 245).

  7. Radar observations of Comet IRAS-Araki-Alcock 1983d

    International Nuclear Information System (INIS)

    Harmon, J.K.; Hine, A.A.; Campbell, D.B.; Shapiro, I.I.; Marsden, B.G.

    1989-01-01

    A detailed analysis and interpretation of the Arecibo S-band radar observations of Comet IRAS-Araki-Alcock 1983d are presented. The very high signal strengths are used to make an accurate determination of the shape of the echo spectrum in the two orthogonal senses of circular polarization. The narrow-band component is used to place constraints on the size, rotation, period, reflectivity, and roughness of the nucleus. Detailed analysis of the broadband component yields estimates of, or bounds on, the spatial extent, position, and mass of the particle cloud, as well as the effective size of the constituent particles. 41 references

  8. Prototype Theory Based Feature Representation for PolSAR Images

    OpenAIRE

    Huang Xiaojing; Yang Xiangli; Huang Pingping; Yang Wen

    2016-01-01

    This study presents a new feature representation approach for Polarimetric Synthetic Aperture Radar (PolSAR) image based on prototype theory. First, multiple prototype sets are generated using prototype theory. Then, regularized logistic regression is used to predict similarities between a test sample and each prototype set. Finally, the PolSAR image feature representation is obtained by ensemble projection. Experimental results of an unsupervised classification of PolSAR images show that our...

  9. The lidar dark band: An oddity of the radar bright band analogy

    Energy Technology Data Exchange (ETDEWEB)

    Sassen, K. [Univ. of Utah, Salt Lake City, UT (United States)

    1996-04-01

    Although much has sbeen learned from independent radar and lidar studies of atmospheric precipitations, occasionally supported by aircraft profiling, what has been lacking is combined optical, microwave, and insitu observations of the melting layer. Fortunately, the rainshowers on April 21, 1994, during the Remote Cloud Sensing intensive obervations Period (RCSIOP) at the Southern Great Plains Cloud and radiation Testbed (CART) site provided an opportunity for coordinated dual-wavelength University of Utah Polarization Diversity Lidar, University of Massachusetts Cloud Profiling Radar System Doppler Radar, and the University of North Dakota Citation aircraft measurements.

  10. CAMEX-4 TOGA RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The TOGA radar dataset consists of browse and radar data collected from the TOGA radar during the CAMEX-4 experiment. TOGA is a C-band linear polarized doppler radar...

  11. P-band radar ice sounding in Antarctica

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kusk, Anders; Kristensen, Steen Savstrup

    2012-01-01

    In February 2011, the Polarimetric Airborne Radar Ice Sounder (POLARIS) was flown in Antarctica in order to assess the feasibility of a potential space-based radar ice sounding mission. The campaign has demonstrated that the basal return is detectable in areas with up to 3 km thick cold ice, in a...

  12. Band Alignment in MoS2/WS2 Transition Metal Dichalcogenide Heterostructures Probed by Scanning Tunneling Microscopy and Spectroscopy.

    Science.gov (United States)

    Hill, Heather M; Rigosi, Albert F; Rim, Kwang Taeg; Flynn, George W; Heinz, Tony F

    2016-08-10

    Using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), we examine the electronic structure of transition metal dichalcogenide heterostructures (TMDCHs) composed of monolayers of MoS2 and WS2. STS data are obtained for heterostructures of varying stacking configuration as well as the individual monolayers. Analysis of the tunneling spectra includes the influence of finite sample temperature, yield information about the quasi-particle bandgaps, and the band alignment of MoS2 and WS2. We report the band gaps of MoS2 (2.16 ± 0.04 eV) and WS2 (2.38 ± 0.06 eV) in the materials as measured on the heterostructure regions and the general type II band alignment for the heterostructure, which shows an interfacial band gap of 1.45 ± 0.06 eV.

  13. Doped Sc2C(OH)2 MXene: new type s-pd band inversion topological insulator.

    Science.gov (United States)

    Balcı, Erdem; Akkuş, Ünal Özden; Berber, Savas

    2018-04-18

    The electronic structures of Si and Ge substitutionally doped Sc 2 C(OH) 2 MXene monolayers are investigated in density functional theory. The doped systems exhibit band inversion, and are found to be topological invariants in Z 2 theory. The inclusion of spin orbit coupling results in band gap openings. Our results point out that the Si and Ge doped Sc 2 C(OH) 2 MXene monolayers are topological insulators. The band inversion is observed to have a new mechanism that involves s and pd states.

  14. Doped Sc2C(OH)2 MXene: new type s-pd band inversion topological insulator

    Science.gov (United States)

    Balcı, Erdem; Özden Akkuş, Ünal; Berber, Savas

    2018-04-01

    The electronic structures of Si and Ge substitutionally doped Sc2C(OH)2 MXene monolayers are investigated in density functional theory. The doped systems exhibit band inversion, and are found to be topological invariants in Z 2 theory. The inclusion of spin orbit coupling results in band gap openings. Our results point out that the Si and Ge doped Sc2C(OH)2 MXene monolayers are topological insulators. The band inversion is observed to have a new mechanism that involves s and pd states.

  15. Andrés Rivera, Escritor social

    Directory of Open Access Journals (Sweden)

    Marta Waldegaray

    2006-07-01

    Full Text Available La narrativa de Andrés Rivera hace de la historia el material de origen de la escritura y de su convicción política de izquierda el molde en el cual desde hace ya más de cuatro décadas su escritura adquiere forma.Acontecimiento histórico, circunstancia política, poseen en sus primeras novelas el valor de verdad política, de testimonio social. La convicción ideológica que sus libros exhiben se acompaña de una trayectoria literaria que, en su práctica inicial, fue confiada a la representación r...

  16. Lunar Noise-Temperature Increase Measurements at S-Band, X-Band, and Ka-Band Using a 34-Meter-Diameter Beam-Waveguide Antenna

    Science.gov (United States)

    Morabito, D. D.

    2006-08-01

    The Moon radiates energy at infrared and microwave wavelengths, in addition to reflecting sunlight at optical wavelengths. As a result, an antenna pointed at or near the Moon will cause an increase in receiver noise temperature that needs to be accounted for in telemetry, radio science, or ranging link budgets. The Deep Space Network may be required to use its antennas in future lunar robotic or human missions, and thus it is important to understand the nature of this temperature increase as a function of observing frequency, lunar phase, and angular offset of the antenna beam from the center of the lunar disk. This article quantifies such a set of measurements acquired at DSS 13, a 34-m-diameter research and development beam-waveguide antenna located at Goldstone, California, at three different telecommunication frequencies, S-band (2.3 GHz), X-band (8.4 GHz), and Ka-band (32 GHz), over a wide range of lunar phase, for both disk-centered and limb-centered positions of the antenna beam.

  17. Cultura e políticas sociais : uma visão a partir da cultura política

    OpenAIRE

    Corrêa, Helena Ariane Borges

    2008-01-01

    A dissertação parte do questionamento de por que fatores culturais não são considerados na formulação de políticas públicas. Para tanto são analisadas e discutidas duas vertentes tradicionalmente separadas na ciência política: culturalismo e institucionalismo, que aqui serão trabalhadas em um nível de análise menos abstrato, relacionando elementos de cultura política com políticas públicas. Com isto o trabalho procura mostrar a relevância do estudo de fatores culturais em políticas sociais e ...

  18. A juventude e a(s política(s: Desinstitucionalização e individualização

    Directory of Open Access Journals (Sweden)

    Nuno Miguel Augusto

    2012-10-01

    Full Text Available A relação que os jovens mantêm com o sistema democrático e, muito particularmente, com os modelos convencionais de participação política tem constituído uma das preocupações fundamentais associadas ao funcionamento e sustentabilidade intergeracional das democracias ocidentais. Frequentemente, a responsabilidade acaba por cair sobre os ombros da própria juventude, tendo por base critérios como a idade, a “irresponsabilidade” ou a “imaturidade”, uma explicação que tem vindo a ser repensada nos últimos anos, como resultado quer da crise de representação, quer das mudanças na condição juvenil. Seguindo uma linha de análise assente numa mútua responsabilização (dos jovens e das instituições políticas procuramos avaliar em que medida a juventude portuguesa reflecte estas tendências e quais os principais motivos para o aparente desencantamento políticos dos jovens. Para tal, cruzámos três dimensões fundamentais – a mobilização política, a confiança e a participação – com o intuito de verificar em que medida as hipóteses teóricas mais recentes poderão contribuir para uma explicação sociologicamente mais sustentada da (escassa relação que os jovens mantêm com a política e com o sistema democrático.

  19. Intermixing, band alignment and charge transport in AgIn5S8/CuI heterojunctions

    International Nuclear Information System (INIS)

    Konovalov, I.; Makhova, L.; Hesse, R.; Szargan, R.

    2005-01-01

    Possibilities of creating photovoltaic devices using CuI/AgIn 5 S 8 heterojunctions are considered. Among other properties, preferential formation of polar (111) surfaces makes n-type AgIn 5 S 8 an attractive candidate for absorber layers of top cells in 4-terminal tandem structures. Cu-Ag exchange at the interface with p-type CuI was observed. This intermixing results in an additional component of Ag 3d5 photoelectron line after deposition of CuI, in the Cu (but not I) contamination of the surface after a chemical removal of CuI, and in a photoelectric sensitivity of the junction at energies below the band gaps. Valence band offsets of 0.4 and 0.5 eV (cliff) were found at interfaces with thin film and bulk AgIn 5 S 8 , supporting a conduction mechanism through interface recombination. Pinning conflict at the interface between materials with contradictory doping limitations is likely to promote the intermixing

  20. Lightning and radar observations of hurricane Rita landfall

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, Bradley G [Los Alamos National Laboratory; Suszcynsky, David M [Los Alamos National Laboratory; Hamlin, Timothy E [Los Alamos National Laboratory; Jeffery, C A [Los Alamos National Laboratory; Wiens, Kyle C [TEXAS TECH U.; Orville, R E [TEXAS A& M

    2009-01-01

    Los Alamos National Laboratory (LANL) owns and operates an array of Very-Low Frequency (VLF) sensors that measure the Radio-Frequency (RF) waveforms emitted by Cloud-to-Ground (CG) and InCloud (IC) lightning. This array, the Los Alamos Sferic Array (LASA), has approximately 15 sensors concentrated in the Great Plains and Florida, which detect electric field changes in a bandwidth from 200 Hz to 500 kHz (Smith et al., 2002). Recently, LANL has begun development of a new dual-band RF sensor array that includes the Very-High Frequency (VHF) band as well as the VLF. Whereas VLF lightning emissions can be used to deduce physical parameters such as lightning type and peak current, VHF emissions can be used to perform precise 3d mapping of individual radiation sources, which can number in the thousands for a typical CG flash. These new dual-band sensors will be used to monitor lightning activity in hurricanes in an effort to better predict intensification cycles. Although the new LANL dual-band array is not yet operational, we have begun initial work utilizing both VLF and VHF lightning data to monitor hurricane evolution. In this paper, we present the temporal evolution of Rita's landfall using VLF and VHF lightning data, and also WSR-88D radar. At landfall, Rita's northern eyewall experienced strong updrafts and significant lightning activity that appear to mark a transition between oceanic hurricane dynamics and continental thunderstorm dynamics. In section 2, we give a brief overview of Hurricane Rita, including its development as a hurricane and its lightning history. In the following section, we present WSR-88D data of Rita's landfall, including reflectivity images and temporal variation. In section 4, we present both VHF and VLF lightning data, overplotted on radar reflectivity images. Finally, we discuss our observations, including a comparison to previous studies and a brief conclusion.

  1. Polarization sensitive behaviour of the band-edge transitions in ReS2 and ReSe2 layered semiconductors

    International Nuclear Information System (INIS)

    Ho, C H; Lee, H W; Wu, C C

    2004-01-01

    The polarization sensitive behaviour of the band-edge transitions in ReS 2 and ReSe 2 layered compounds was studied using polarized-transmission and polarized-thermoreflectance (PTR) measurements with polarization angles from θ = 0 deg. (Evector parallel b-axis) to θ = 90 deg. (Evector perpendicular b-axis) at 300 K. The polarization dependence of the polarized energy gaps of ReS 2 and ReSe 2 shows a sinusoidal-like variation with respect to the angular change of the linearly polarized light. The angular dependences of the polarized energy gaps of ReS 2 and ReSe 2 were evaluated. The polarization sensitive behaviour of the band-edge excitons in rhenium disulfide and diselenide was characterized using angular dependent PTR measurements from θ = 0 deg. to 90 deg. The polarized transition intensities of the band-edge excitons (E 1 ex and E 2 ex ) of ReX 2 (X = S, Se) demonstrate a sinusoidal variation with respect to the angular change of the linearly polarized light. The angular dependence of the polarized transition probabilities of E 1 ex and E 2 ex is analysed. The polarization sensitive behaviours of ReX 2 (X = S, Se) layers are discussed

  2. ¿Señales de esperanza en Euskadi? El País Vasco después de las elecciones autonómicas: partidos políticos, sociedad civil y perspectivas de paz

    Directory of Open Access Journals (Sweden)

    Andreas Baumer

    2014-06-01

    Full Text Available En el País Vasco se está acostumbrado a que los hechos suelan ser peores que los temores más pesimistas. El caso de las elecciones autonómicas del 13 de mayo de 2001 es la famosa excepción que confirma la regla. En contra de lo esperado por algunos sondeos, que dibujaban escenarios de catástrofes aritméticas o políticas, los resultados de las elecciones reflejan el apoyo a un nacionalismo moderado y el rechazo de opciones radicales que supongan cambios sustanciales.

  3. Size-dependent and intra-band photoluminescence of NiS2 nano-alloys synthesized by microwave assisted hydrothermal technique

    International Nuclear Information System (INIS)

    Linganiso, Ella Cebisa; Mhlanga, Sabelo Dalton; Coville, Neil John; Mwakikunga, Bonex Wakufwa

    2013-01-01

    Graphical abstract: Unexpected ultra-violet (UV) emission as well as near infra-red (IR) emissions were attributed to intra-band energy state transitions that occur as a result of the porous structure of the material. Enhanced UV and near IR PL emissions due to the smaller crystallite size of the capped NiS 2 nanostructures was also observed. Band energy and local density of states calculation for NiS 2 were used to support the experimentally observed luminescence results. The luminescence features at wavelengths of 400 nm (3.10 eV), 428 nm (2.90 eV), 447 nm (2.77 eV) and 464 nm (2.67) can be attributed to some of those electrons de-exciting from S (3p) levels down to the Ni (3d) (blue to UV emission) whereas those features at wavelengths of 710 nm (1.75 eV), 751 nm (1.65 eV), 754 nm (1.64 eV) [NiS 2 /HDA-capped NiS 2 ] and 784 nm (1.58 eV) respectively seem to result from de-excitations between either Ni(3d) or S (3s, 3p) levels and Ni–S hybridization levels (red to near IR emission). Highlights: ► Rapid solid state alloying of Ni and S from their liquid state precursor by microwaves. ► New photoluminescence data of NiS 2 system. ► Unexpected luminescence in the UV–Visible and near IR ranges for such a metal matrix alloy. ► Explanation of NiS 2 photoluminescence from ab initio calculations by electronic energy band structure and density of states. -- Abstract: Synthesis of nickel disulfide (NiS 2 ) nano-alloys capped and uncapped with hexadecylamine (HDA) was carried out. A cubic phase NiS 2 formation was confirmed by X-ray diffraction (XRD) analysis. An average crystallite size of 35 nm was obtained for the uncapped nanostructures and 9 nm was obtained for the capped nanostructures estimated using the Scherrer equation. Unexpected ultra-violet (UV) emission as well as near infrared (IR) emissions were attributed to intra-band energy state transitions that occur as a result of the porous structure of the material. Enhanced UV and near IR PL emissions

  4. AirMOSS P-Band Radar Retrieval of Subcanopy Soil Moisture Profile

    Science.gov (United States)

    Tabatabaeenejad, A.; Burgin, M. S.; Duan, X.; Moghaddam, M.

    2013-12-01

    Knowledge of soil moisture, as a key variable of the Earth system, plays an important role in our under-standing of the global water, energy, and carbon cycles. The importance of such knowledge has led NASA to fund missions such as Soil Moisture Active and Passive (SMAP) and Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS). The AirMOSS mission seeks to improve the estimates of the North American Net Ecosystem Exchange (NEE) by providing high-resolution observations of the root zone soil moisture (RZSM) over regions representative of the major North American biomes. AirMOSS flies a P-band SAR to penetrate vegetation and into the root zone to provide estimates of RZSM. The flights cover areas containing flux tower sites in regions from the boreal forests in Saskatchewan, Canada, to the tropical forests in La Selva, Costa Rica. The radar snapshots are used to generate estimates of RZSM via inversion of a scattering model of vegetation overlying soils with variable moisture profiles. These retrievals will be used to generate a time record of RZSM, which will be integrated with an ecosystem demography model in order to estimate the respiration and photosynthesis carbon fluxes. The aim of this work is the retrieval of the moisture profile over AirMOSS sites using the collected P-band radar data. We have integrated layered-soil scattering models into a forest scattering model; for the backscattering from ground and for the trunk-ground double-bounce mechanism, we have used a layered small perturbation method and a coherent scattering model of layered soil, respectively. To estimate the soil moisture profile, we represent it as a second-order polynomial in the form of az2 + bz + c, where z is the depth and a, b, and c are the coefficients to be retrieved from radar measurements. When retrieved, these coefficients give us the soil moisture up to a prescribed depth of validity. To estimate the unknown coefficients of the polynomial, we use simulated

  5. Impact of Antibody Bioconjugation on Emission and Energy Band Profile of CdSeTe/ZnS Quantum Dots

    Science.gov (United States)

    Torchynska, T. V.; Gomez, J. A. Jaramillo; Polupan, G.; Macotela, L. G. Vega

    2018-03-01

    The variation of the photoluminescence (PL) and Raman scattering spectra of CdSeTe/ZnS quantum dots (QDs) on conjugation to an antibody has been investigated. Two types of CdSeTe/ZnS QD with different emission wavelength (705 nm and 800 nm) were studied comparatively before and after conjugation to anti-pseudorabies virus antibody (AB). Nonconjugated QDs were characterized by Gaussian-type PL bands. PL shifts to higher energy and asymmetric shape of PL bands was detected in PL spectra of bioconjugated QDs. The surface-enhanced Raman scattering effect was exhibited by the bioconjugated CdSeTe/ZnS QDs, indicating that the excitation light used in the Raman study generated electric dipoles in the AB molecules. The optical bandgap of the CdSeTe core was calculated numerically as a function of its radius based on an effective mass approximation model. The energy band diagrams for non- and bioconjugated CdSeTe/ZnS QDs were obtained, revealing a type II quantum well in the CdSeTe core. The calculations show that AB dipoles, excited in the bioconjugated QDs, stimulate a change in the energy band diagram of the QDs that alters the PL spectrum. These results could be useful for improving the sensitivity of QD biosensors.

  6. Electronic structure of SnS deduced from photoelectron spectra and band-structure calculations

    NARCIS (Netherlands)

    Ettema, A.R.H.F.; Groot, R.A. de; Haas, C.; Turner, T.S.

    1992-01-01

    SnS is a layer compound with a phase transition from a high-temperature β phase to a low-temperature α phase with a lower symmetry. Ab initio band-structure calculations are presented for both phases. The calculations show that the charge distributions in the two phases are very similar. However,

  7. Observation of Whole Flushing Process of a River Sand Bar by a Flood Using X-Band Radar

    Directory of Open Access Journals (Sweden)

    Satoshi Takewaka

    2016-05-01

    Full Text Available Morphological changes during a flood event in July 2010 were observed with X-band marine radar at the mouth of Tenryu River, Shizuoka, Japan. Radar images were collected hourly for more than 72 h from the beginning of the flood and processed into time-averaged images. Changes in the morphology of the area were interpreted from the time-averaged images, revealing that the isolated river dune was washed away by the flood, the width of the river mouth increased gradually, and the river mouth terrace expanded radially. Furthermore, image analysis of the radar images was applied to estimate the migration speed of the brightness pattern, which is assumed to be a proxy of bottom undulation of the river bed. The migration was observed to be faster when the water level gradient between the river channel and sea increased.

  8. Políticas de reconhecimento uma novidade das políticas sociais do PT?

    Directory of Open Access Journals (Sweden)

    Krischke, Paulo Jose Duval da Silva

    2004-01-01

    Full Text Available O presente trabalho levanta a hipótese de que as ações de governo do PT estão inovando significativamente na necessária convergência (cf. Fraser, 1999; Honnetch, 2003 entre as tradicionais políticas de redistribuição sócio-econômica, e uma nova diretriz de reconhecimento das diferenças sócio-políticas e culturais. O argumento retoma a trajetória sindical do PT e os efeitos das políticas participativas, nas mudanças da cultura política em várias partes do país. Entre esses efeitos, o crescente apoio à democracia parece relacionar-se ao reconhecimento do direito à diferença e ao pluralismo - principalmente entre a juventude e naqueles locais onde o PT tem governado na última década

  9. Generation of nanosecond S band microwave pulses based on superradiance

    International Nuclear Information System (INIS)

    Ginzburg, N.S.; Zotova, I.V.; Rozental, R.M.

    2002-01-01

    Modeling carried out demonstrates possibility of generation of gigawatt power level S band microwave pulse with duration of several nanoseconds using superradiation of short electron beam moving along slow-wave periodical structure. A 10 ns / 500 keV / 5 kA accelerator of Kanazawa University can be used in such experiments. It is shown that significant increasing peak power can be obtained by optimization of voltage and current pulses waveforms. Required increasing of electron energy and current by the end of electron pulse can be achieved by using self-acceleration of a short beam passing through a system of passive cavities. (author)

  10. Generation of nanosecond S band microwave pulses based on superradiance

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, N.S.; Zotova, I.V.; Rozental, R.M. [Russian Academy of Science, Institute of Applied Physics, Nizhny Novgorod (RU)] [and others

    2002-06-01

    Modeling carried out demonstrates possibility of generation of gigawatt power level S band microwave pulse with duration of several nanoseconds using superradiation of short electron beam moving along slow-wave periodical structure. A 10 ns / 500 keV / 5 kA accelerator of Kanazawa University can be used in such experiments. It is shown that significant increasing peak power can be obtained by optimization of voltage and current pulses waveforms. Required increasing of electron energy and current by the end of electron pulse can be achieved by using self-acceleration of a short beam passing through a system of passive cavities. (author)

  11. Estimation of mesospheric vertical winds from a VHF meteor radar at King Sejong Station, Antarctica (62.2S, 58.8W)

    Science.gov (United States)

    Kim, Y.; Lee, C.; Kim, J.; Jee, G.

    2013-12-01

    For the first time, vertical winds near the mesopause region were estimated from radial velocities of meteor echoes detected by a VHF meteor radar at King Sejong Station (KSS) in 2011 and 2012. Since the radar usually detects more than a hundred echoes every hour in an altitude bin of 88 - 92 km, much larger than other radars, we were able to fit measured radial velocities of these echoes with a 6 component model that consists of horizontal winds, spatial gradients of horizontal winds and vertical wind. The conventional method of deriving horizontal winds from meteor echoes utilizes a 2 component model, assuming that vertical winds and spatial gradients of horizontal winds are negligible. We analyzed the radar data obtained for 8400 hours in 2012 and 8100 hours in 2011. We found that daily mean values of vertical winds are mostly within +/- 1 m/s, whereas those of zonal winds are a few tens m/s mostly eastward. The daily mean vertical winds sometimes stay positive or negative for more than 20 days, implying that the atmosphere near the mesopause experiences episodically a large scale low and high pressure environments, respectively, like the tropospheric weather system. By conducting Lomb-normalized periodogram analysis, we also found that the vertical winds have diurnal, semidiurnal and terdiurnal tidal components with about equal significance, in contrast to horizontal winds that show a dominant semidiurnal one. We will discuss about uncertainties of the estimated vertical wind and possible reasons of its tidal and daily variations.

  12. An X-Band Radar System for Bathymetry and Wave Field Analysis in a Harbour Area

    Directory of Open Access Journals (Sweden)

    Giovanni Ludeno

    2015-01-01

    Full Text Available Marine X-band radar based systems are well tested to provide information about sea state and bathymetry. It is also well known that complex geometries and non-uniform bathymetries provide a much bigger challenge than offshore scenarios. In order to tackle this issue a retrieval method is proposed, based on spatial partitioning of the data and the application of the Normalized Scalar Product (NSP, which is an innovative procedure for the joint estimation of bathymetry and surface currents. The strategy is then applied to radar data acquired around a harbour entrance, and results show that the reconstructed bathymetry compares well with ground truth data obtained by an echo-sounder campaign, thus proving the reliability of the whole procedure. The spectrum thus retrieved is then analysed to show the evidence of reflected waves from the harbour jetties, as confirmed by chain of hydrodynamic models of the sea wave field. The possibility of using a land based radar to reveal sea wave reflection is entirely new and may open up new operational applications of the system.

  13. S-band low noise amplifier and 40 kW high power amplifier subsystems of Japanese Deep Space Earth Station

    Science.gov (United States)

    Honma, K.; Handa, K.; Akinaga, W.; Doi, M.; Matsuzaki, O.

    This paper describes the design and the performance of the S-band low noise amplifier and the S-band high power amplifier that have been developed for the Usuda Deep Space Station of the Institute of Space and Astronautical Science (ISAS), Japan. The S-band low noise amplifier consists of a helium gas-cooled parametric amplifier followed by three-stage FET amplifiers and has a noise temperature of 8 K. The high power amplifier is composed of two 28 kW klystrons, capable of transmitting 40 kW continuously when two klystrons are combined. Both subsystems are operating quite satisfactorily in the tracking of Sakigake and Suisei, the Japanese interplanetary probes for Halley's comet exploration, launched by ISAS in 1985.

  14. Molecular beam and pulsed laser deposition of ZnS:Cr for intermediate band solar cells

    OpenAIRE

    Nematollahi, Mohammadreza; Yang, Xiaodong; Aas, Lars Martin Sandvik; Ghadyani, Zahra; Kildemo, Morten; Gibson, Ursula; Reenaas, Turid Worren

    2015-01-01

    We have investigated the structural and optical properties of Cr-doped ZnS (ZnS:Cr) thin films (0–7.5 at.% Cr) for use in intermediate band solar cells. The films were grown on Si(100) in molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) equipments. Introducing Cr into ZnS resulted in Cr related subbandgap absorption, but also reduced the grain size. The sub-bandgap absorption increased with increasing Cr content, and with increasing growth temperature, but did not depend on the ...

  15. Validation of attenuation, beam blockage, and calibration estimation methods using two dual polarization X band weather radars

    Science.gov (United States)

    Diederich, M.; Ryzhkov, A.; Simmer, C.; Mühlbauer, K.

    2011-12-01

    The amplitude a of radar wave reflected by meteorological targets can be misjudged due to several factors. At X band wavelength, attenuation of the radar beam by hydro meteors reduces the signal strength enough to be a significant source of error for quantitative precipitation estimation. Depending on the surrounding orography, the radar beam may be partially blocked when scanning at low elevation angles, and the knowledge of the exact amount of signal loss through beam blockage becomes necessary. The phase shift between the radar signals at horizontal and vertical polarizations is affected by the hydrometeors that the beam travels through, but remains unaffected by variations in signal strength. This has allowed for several ways of compensating for the attenuation of the signal, and for consistency checks between these variables. In this study, we make use of several weather radars and gauge network measuring in the same area to examine the effectiveness of several methods of attenuation and beam blockage corrections. The methods include consistency checks of radar reflectivity and specific differential phase, calculation of beam blockage using a topography map, estimating attenuation using differential propagation phase, and the ZPHI method proposed by Testud et al. in 2000. Results show the high effectiveness of differential phase in estimating attenuation, and potential of the ZPHI method to compensate attenuation, beam blockage, and calibration errors.

  16. Non-contact acquisition of respiration and heart rates using Doppler radar with time domain peak-detection algorithm.

    Science.gov (United States)

    Xiaofeng Yang; Guanghao Sun; Ishibashi, Koichiro

    2017-07-01

    The non-contact measurement of the respiration rate (RR) and heart rate (HR) using a Doppler radar has attracted more attention in the field of home healthcare monitoring, due to the extremely low burden on patients, unconsciousness and unconstraint. Most of the previous studies have performed the frequency-domain analysis of radar signals to detect the respiration and heartbeat frequency. However, these procedures required long period time (approximately 30 s) windows to obtain a high-resolution spectrum. In this study, we propose a time-domain peak detection algorithm for the fast acquisition of the RR and HR within a breathing cycle (approximately 5 s), including inhalation and exhalation. Signal pre-processing using an analog band-pass filter (BPF) that extracts respiration and heartbeat signals was performed. Thereafter, the HR and RR were calculated using a peak position detection method, which was carried out via LABVIEW. To evaluate the measurement accuracy, we measured the HR and RR of seven subjects in the laboratory. As a reference of HR and RR, the persons wore contact sensors i.e., an electrocardiograph (ECG) and a respiration band. The time domain peak-detection algorithm, based on the Doppler radar, exhibited a significant correlation coefficient of HR of 0.92 and a correlation coefficient of RR of 0.99, between the ECG and respiration band, respectively.

  17. E-region decameter-scale plasma waves observed by the dual TIGER HF radars

    Directory of Open Access Journals (Sweden)

    B. A. Carter

    2009-01-01

    Full Text Available The dual Tasman International Geospace Environment Radar (TIGER HF radars regularly observe E-region echoes at sub-auroral magnetic latitudes 58°–60° S including during geomagnetic storms. We present a statistical analysis of E-region backscatter observed in a period of ~2 years (late 2004–2006 by the TIGER Bruny Island and Unwin HF radars, with particular emphasis on storm-time backscatter. It is found that the HF echoes normally form a 300-km-wide band at ranges 225–540 km. In the evening sector during geomagnetic storms, however, the HF echoes form a curved band joining to the F-region band at ~700 km. The curved band lies close to the locations where the geometric aspect angle is zero, implying little to no refraction during geomagnetic storms, which is an opposite result to what has been reported in the past. The echo occurrence, Doppler velocity, and spectral width of the HF echoes are examined in order to determine whether new HF echo types are observed at sub-auroral latitudes, particularly during geomagnetic storms. The datasets of both TIGER radars are found to be dominated by low-velocity echoes. A separate population of storm-time echoes is also identified within the datasets of both radars with most of these echoes showing similar characteristics to the low-velocity echo population. The storm-time backscatter observed by the Bruny Island radar, on the other hand, includes near-range echoes (r<405 km that exhibit some characteristics of what has been previously termed the High Aspect angle Irregularity Region (HAIR echoes. We show that these echoes appear to be a storm-time phenomenon and further investigate this population by comparing their Doppler velocity with the simultaneously measured F- and E-region irregularity velocities. It is suggested that the HAIR-like echoes are observed only by HF radars with relatively poor geometric aspect angles when electron density is low and when the electric field is particularly

  18. Electronic structure investigation of MoS2 and MoSe2 using angle-resolved photoemission spectroscopy and ab initio band structure studies.

    Science.gov (United States)

    Mahatha, S K; Patel, K D; Menon, Krishnakumar S R

    2012-11-28

    Angle-resolved photoemission spectroscopy (ARPES) and ab initio band structure calculations have been used to study the detailed valence band structure of molybdenite, MoS(2) and MoSe(2). The experimental band structure obtained from ARPES has been found to be in good agreement with the theoretical calculations performed using the linear augmented plane wave (LAPW) method. In going from MoS(2) to MoSe(2), the dispersion of the valence bands decreases along both k(parallel) and k(perpendicular), revealing the increased two-dimensional character which is attributed to the increasing interlayer distance or c/a ratio in these compounds. The width of the valence band and the band gap are also found to decrease, whereas the valence band maxima shift towards the higher binding energy from MoS(2) to MoSe(2).

  19. Structure design for a 500 GeV S-band linear collider

    International Nuclear Information System (INIS)

    Hahne, P.; Holtkamp, N.; Klatt, R.; Weiland, T.

    1991-01-01

    Constant gradient structures with an accelerating gradient of 20 MeV per meter are commonly used with S-band frequency. The well known features of these travelling wave tubes provide a dedicated design for their use in the next generation linear collider. Some of the required design parameters for this tubes are presented within the whole concept of this collider with an active length of about 30 km. The choice of these parameters is explained and calculations concerning the structure are presented

  20. Optical properties and band structure of atomically thin MoS2

    Science.gov (United States)

    Shan, Jie; Mak, Kin Fai; Lee, Changgu; Hone, James; Heinz, Tony

    2010-03-01

    Atomically thin layers of materials can be expected to exhibit distinct electronic structure and novel properties compared to their bulk counterparts. Layered compounds, for which stable atomically thin samples can be produced, are ideal candidates for such studies. Graphene, a monolayer slice of the graphite crystal, is an illustrative example of both the stability and of the interest and importance of such materials. Here we report a study of thin layers of MoS2, a hexagonal layered bulk semiconductor with an indirect band gap of 1.3 eV. MoS2 samples with layer thickness N down to a monolayer were obtained by mechanical exfoliation. We observed an enhancement of the luminescence quantum yield by more than a factor of 100 in monolayer MoS2 compared to the bulk material. The combination of absorption, photoluminescence, and photoconductivity measurements indicates that a transition to a direct-gap material occurs in the limit of the single MoS2 layer. This result is supported by an earlier first-principles calculation [J. Phys. Chem. C 2007, 111, 16192]. Further, by varying the thickness of the samples, we were able to probe the evolution of the electronic structure for N = 1 -- 6 layers.

  1. El humor político clandestino. ¿La crítica más temida de todo régimen?

    OpenAIRE

    Diego Hernando Gómez

    2016-01-01

    Resenha da obra: Várnagy, Tomás: “Proletarios de todos los países… ‘Perdonadnos!” El humor político clandestino en los regímenes de tipo soviético y el papel deslegitimador del chiste en Europa central y oriental (1917-1991). Buenos Aires: EUDEBA (Editorial Universitaria de Buenos Aires), 2016. 372 páginas.

  2. GPM GROUND VALIDATION NOAA S-BAND PROFILER ORIGINAL DWELL DATA MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The S-band Profiler Original Dwell dataset in the netCDF format was gathered during the Midlatitude Continental Convective Clouds Experiment (MC3E) in Oklahoma...

  3. Bubbles in Titan’s Seas: Nucleation, Growth, and RADAR Signature

    Science.gov (United States)

    Cordier, Daniel; Liger-Belair, Gérard

    2018-05-01

    In the polar regions of Titan, the main satellite of Saturn, hydrocarbon seas have been discovered by the Cassini–Huygens mission. RADAR observations have revealed surprising and transient bright areas over the Ligeia Mare surface. As suggested by recent research, bubbles could explain these strange features. However, the nucleation and growth of such bubbles, together with their RADAR reflectivity, have never been investigated. All of these aspects are critical to an actual observation. We have thus applied the classical nucleation theory to our context, and we developed a specific radiative transfer model that is appropriate for bubble streams in cryogenic liquids. According to our results, the sea bed appears to be the most plausible place for the generation of bubbles, leading to a signal comparable to observations. This conclusion is supported by thermodynamic arguments and by RADAR properties of a bubbly column. The latter are also valid in the case of bubble plumes, due to gas leaking from the sea floor.

  4. S-band 300 W pulsed solid state microwave amplifier development for driving high power klystrons for electron accelerators

    International Nuclear Information System (INIS)

    Mohania, Praveen; Shrivastava, Purushottam; Hannurkar, P.R.

    2005-01-01

    S-Band Microwave electron accelerators like microtrons and linear accelerators need pulsed microwaves from few megawatts to tens of megawatts to accelerator the electrons to desired energy and intensity. Klystron tube based driver amplifiers were used to drive the high power klystrons, which need microwave power from few tens of watts to 1 kW depending on tube output power and gain. A endeavour was initiated at Centre for Advanced Technology to develop state of art solid state S-band microwave amplifiers indigenously to drive the klystron tubes. A modular design approach was used and individual modules up to 160 W power levels were developed and tested. Finally combining 160 W modules will give up to 300 W output power. Several more modules can be combined to achieve even high power levels. Present paper describes the developmental efforts of 300 W S-band solid-state amplifiers and related microwave technologies. (author)

  5. Capacity Enhancement for Hybrid Fiber-Wireless Channels with 46.8Gbit/sWireless Multi-CAP Transmission over 50m at W-Band

    DEFF Research Database (Denmark)

    Rommel, Simon; Puerta Ramírez, Rafael; Vegas Olmos, Juan José

    2017-01-01

    Transmission of a 46.8 Gbit/s multi-band CAP signal is experimentally demonstrated over a 50 m W-band radio-over-fiber link. Bit error rates below 3.8×10-3 are achieved, employing nine CAP bands with bit and power loading.......Transmission of a 46.8 Gbit/s multi-band CAP signal is experimentally demonstrated over a 50 m W-band radio-over-fiber link. Bit error rates below 3.8×10-3 are achieved, employing nine CAP bands with bit and power loading....

  6. La política de la protesta en regímenes autoritarios: síntesis crítica

    Directory of Open Access Journals (Sweden)

    Felipe Sánchez Barría

    Full Text Available RESUMEN Introducción A través de una revisión crítica de la literatura reciente, el ensayo explora la relación entre protesta contenciosa y regímenes autoritarios, y examina las dinámicas y consecuencias que emergen durante el conflicto político. Métodos Para lo anterior se discuten tres elementos que los especialistas han identificado como los principales en esta relación: oportunidades y amenazas políticas; ciclos de protesta y sostenibilidad de los movimientos sociales; y la relación entre violencia estatal y acción colectiva. Resultados La recurrencia de la protesta en regímenes represivos muestra la capacidad de la sociedad civil para articular este tipo de acciones contenciosas. Discusión No obstante, las trayectorias y resultados dependen, por una parte, de las características políticas del régimen y la competencia del gobierno para responder a los desafíos colectivos; y, por otra parte, de la capacidad de los oponentes de montar ciclos de protestas densos en participación durante un periodo significativo, del tipo de tácticas adoptadas, y de la capacidad de adaptación y resiliencia a la violencia estatal.

  7. Políticas de turismo no Rio de Janeiro pós-fusão: programas para interiorização do turismo no estado

    Directory of Open Access Journals (Sweden)

    Pãmela Ketulin Mattos Gomes

    2017-11-01

    Full Text Available Este artigo visa a contribuir para o conhecimento do processo de constituição das políticas públicas voltadas para o setor do turismo no estado do Rio de Janeiro, tanto as produzidas na esfera federal quanto na estadual, priorizando aquelas que incentivaram interiorização das atividades do setor. O artigo também privilegia a dimensão espacial ao resgatar os instrumentos de regionalização contidos nos programas e ações atrelados às políticas, buscado entender como as opções políticas afetam o território.

  8. Performance of high power S-band klystrons focused with permanent magnet

    International Nuclear Information System (INIS)

    Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

    1987-02-01

    Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 % of the longitudinal field in the entire rf interaction region of the klystron. (author)

  9. Performance of high power S-band klystrons focused with permanent magnet

    Science.gov (United States)

    Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

    1987-02-01

    Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 percent of the longitudinal field in the entire RF interaction region of the klystron.

  10. Design of a New ENG Metamaterial for S-Band Microwave Applications

    Directory of Open Access Journals (Sweden)

    ISLAM Sikder Sunbeam

    2014-10-01

    Full Text Available In this paper we propose a new metamaterial unit cell structure on FR-4 substrate material that shows resonance in the microwave S-Band frequency range and also shows negative permittivity at that frequency. The material shows better performances with two resonances and Double Negative characteristics if Rogers RT 6010 substrate material is used. In this design two separate split ring resonators is used. We have used the CST Microwave Studio simulation software to get the reflection and transmission parameters for this unit cell.

  11. Design of a high repetition rate S-band photocathode gun

    International Nuclear Information System (INIS)

    Han Janghui; Cox, Matthew; Huang, Houcheng; Pande, Shivaji

    2011-01-01

    Photocathode RF guns have been developed in many laboratories for generating high quality electron beams for free-electron lasers based on linear accelerators. Such guns can generate electron beams with an exceptionally high peak current as well as a small transverse emittance. Their applications have been recently expanded for ultrafast electron diffraction, coherent terahertz radiation, and X-ray or γ-ray radiation by Compton scattering. In this paper, we design an S-band normal-conducting gun with capabilities of high quality beam generation and high repetition rate operation. The RF design and thermal analysis of the gun cavity and coupler are introduced. Optimal position of the gun focusing solenoid for low emittance beam generation is found by performing particle tracking simulations. Then, the gun system is designed to be able to afford the optimal solenoid position. The cooling-water channel surrounding the gun cavity and coupler is designed and analyzed numerically. The pressure in the gun is simulated with a vacuum model containing the detailed inner structure of the gun. An injector for a free-electron laser application is designed by using this gun and the beam dynamics simulation is shown. A cold test with a prototype gun for confirmation of the RF design is reported. - Highlights: → We design an S-band gun for low emittance beam generation and high repetition rate operation. → The RF design and thermal analysis of the gun cavity and coupler are studied. → An FEL injector is designed by using this gun and the beam dynamics simulation is shown. → A cold test with a prototype gun for confirmation of the RF design is reported.

  12. Impact of dual-polarization radar technology and Twitter on the Hattiesburg, Mississippi tornado.

    Science.gov (United States)

    Cates, Alexis L; Arnold, Brent W; Cooper, Guy Paul; Yeager, Violet; Stake, Josh; Ali, Mohammed; Calderone, Richard C; Wilkinson, James; Hsu, Edbert; Parrillo, Steven; Piper, Steven; Subbarao, Italo

    2013-12-01

    Dual-Polarization Radar and Twitter were analyzed to determine the impact on injuries sustained by the Hattiesburg EF-4 tornado. Tracking data provided from the Dual-Pol radar systems in National Weather Service Jackson were reviewed. Twitter data from four local Twitter handles were obtained. The change in tweets and followers for the day of the storm were compared to historical averages. A Student t-test was utilized in determining statistical significance (ptornado. An Injury Severity Score (ISS) was calculated for trauma records related to the tornado. Radar detection of the tornado gave approximately 30 minutes of advanced warning time. Statistical significance in follower growth was seen in all four Twitter handles. Out of 50 patients, the average ISS was 3.9 with a range of 1 to 29. There were zero fatalities. An ISS average of 3.9 was significantly less than two previous tornadoes of similar strength that occurred prior to increased usage of Dual-pol radar and Twitter as a means for communicating severe weather information. Early detection from Dual-pol radar improved warning time. Tweets informed citizens to seek appropriate shelter. (Disaster Med Public Health Preparedness. 2013;7:585-592).

  13. Participo (online, luego existo. Un análisis de la participación social y política a través de internet en España

    Directory of Open Access Journals (Sweden)

    AMPARO Novo VÁZQUEZ

    2014-01-01

    Full Text Available Partimos del supuesto general de que los diferentes recursos con los que cuenta la ciudadanía estructuran sus oportunidades de participación social y política a través de Internet. De este modo, analizamos cuáles son los factores sociodemográficos que influyen en el uso de Internet para realizar determinadas acciones sociales y políticas. En concreto, estudiamos los determinantes de la implicación social y política de los ciudadanos en Internet a través de la emisión de opiniones y de la participación en consultas o votaciones sobre asuntos políticos y cívicos. Los resultados obtenidos sugieren que la mayor participación se da entre los jóvenes y sorprendentemente entre las personas en situación de desempleo. También se aprecia que la brecha de género existente en la participación offline se traslada al entorno virtual.

  14. Testing and use of radar water level sensors by the U.S. Geological Survey

    Science.gov (United States)

    Fulford, Janice M.

    2016-01-01

    The United States Geological Survey uses water-level (or stage) measurements to compute streamflow at over 8000 stream gaging stations located throughout the United States (waterwatch.usgs.gov, 2016). Streamflow (or discharge) is computed at five minute to hourly intervals from a relationship between water level and discharge that is uniquely determined for each station. The discharges are posted hourly to WaterWatch (waterwatch. usgs.gov) and are used by water managers to issue flood warnings and manage water supply and by other users of water information to make decisions. The accuracy of the water-level measurement is vital to the accuracy of the computed discharge. Because of the importance of water-level measurements, USGS has an accuracy policy of 0.02 ft or 0.2 percent of reading (whichever is larger) (Sauer and Turnipseed, 2010). Older technologies, such as float and shaft-encoder systems, bubbler systems and submersible pressure sensors, provide the needed accuracy but often require extensive construction to install and are prone to malfunctioning and damage from floating debris and sediment. No stilling wells or orifice lines need to be constructed for radar installations. During the last decade testing by the USGS Hydrologic Instrumentation Facility(HIF) found that radar water-level sensors can provide the needed accuracy for water-level measurements and because the sensor can be easily attached to bridges, reduce the construction required for installation. Additionally, the non-contact sensing of water level minimizes or eliminates damage and fouling from floating debris and sediment. This article is a brief summary of the testing efforts by the USGS HIF and field experiences with models of radar water-level sensors in streamflow measurement applications. Any use of trade names in this article is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  15. A expansão da educação superior em Goiás na interseção com as políticas públicas do governo estadual

    OpenAIRE

    Silva,Agnaldo José da

    2008-01-01

    O presente estudo versa sobre a recente expansão da educação superior no Estado de Goiás, enfatizando as políticas públicas do governo estadual destinadas a esse nível de ensino. Mais precisamente analisa a criação e expansão da Universidade Estadual de Goiás (UEG) e a implementação do Programa Bolsa Universitária do governo estadual em parceria com a Organização das Voluntárias de Goiás (OVG). O estudo em questão procura mostrar que as políticas governamentais de criação da UE...

  16. Characterestics of pico-second single bunch at the S-band linear accelerator

    International Nuclear Information System (INIS)

    Uesaka, Mitsuru; Kozawa, Takahiro; Kobayashi, Toshiaki; Ueda, Toru; Miya, Kenzo

    1994-01-01

    Measurement of the bunch structure of a pico-second single bunch was performed using a femto-second streak camera at the S-band linear accelerator of the University of Tokyo. The aim of this research is to investigate the feasibility of the generation of a femto-second single bunch at the S-band linac. The details of the bunch structure and energy spectrum of an original single bunch were precisely investigated in several operation modes where the RF phases in accelerating tubes and a prebuncher were varied. The femto-second streak camera was utilized to measure the bunch structure by one shot via Cherenkov radiation emitted by the electrons in the bunch. Next, an experiment for magnetic pulse compression of the original single bunch was carried out. Pulse shapes of the compressed bunchs for different energy modulation were also obtained by measuring Cherenkov radiation by one shot using the femto-second streak camera. Prior to the experiment, numerical tracking analysis to determine operating parameters for the magnetic pulse compression was also done. Measured pulse widths were compared with calculated ones. Finally, a 2 ps (full width at half maximum; FWHM) single bunch with an electric charge of 0.3 nC could be generated by the magnetic pulse compression. ((orig.))

  17. Review of studies on conventional linear colliders in the S- and X-Band regime

    International Nuclear Information System (INIS)

    Loew, G.A.

    1992-07-01

    This paper gives a status report on the conventional approaches to linear colliders at DESY, KEK, SLAC and INP-Protvino in the S- and X-Band regime. Critical topics are reviewed and a discussion of global issues such as future R ampersand D requirements is included

  18. Analysis of 35 GHz Cloud Radar polarimetric variables to identify stratiform and convective precipitation.

    Science.gov (United States)

    Fontaine, Emmanuel; Illingworth, Anthony, J.; Stein, Thorwald

    2017-04-01

    This study is performed using vertical profiles of radar measurements at 35GHz, for the period going from 29th of February to 1rst October 2016, at the Chilbolton observatory in United Kingdom. During this period, more than 40 days with precipitation events are investigated. The investigation uses the synergy of radar reflectivity factors, vertical velocity, Doppler spectrum width, and linear depolarization ratio (LDR) to differentiate between stratiform and convective rain events. The depth of the layer with Doppler spectrum width values greater than 0.5 m s-1 is shown to be a suitable proxy to distinguish between convective and stratiform events. Using LDR to detect the radar bright band, bright band characteristics such as depth of the layer and maximum LDR are shown to vary with the amount of turbulence aloft. Profiles of radar measurements are also compared to rain gauge measurements to study the contribution of convective and stratiform rainfall to total rain duration and amount. To conclude, this study points out differences between convective and stratiform rains and quantifies their contributions over a precipitation event, highlighting that convective and stratiform rainfall should be considered as a continuum rather than a dichotomy.

  19. Two orthogonal carriers assisted 101-Gb/s dual-band DDO-OFDM transmission over 320-km SSMF.

    Science.gov (United States)

    Chen, Yiqin; Hu, Rong; Yang, Qi; Luo, Ming; Yu, Shaohua; Li, Wei

    2015-05-04

    We propose a novel fading-free direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) scheme for 100-Gb/s medium-reach transmission. In the proposed scheme, we adopts two bands spaced at 100-GHz to accommodate the same complex-valued OFDM signal. However, the signals are coupled with a pair of orthogonal optical carriers. By doing so, real and imaginary parts of the complex-valued OFDM signal can be recovered from the two bands, respectively. We also propose a cost-effective scheme to generate such DDO-OFDM signal using an optical 90-degree hybrid and an optical I/Q modulator. The advantage of the proposed method is that it is fading-free, and the electrical spectral efficiency (SE) is doubled compared to traditional direct-detection method. Finally, we experimentally demonstrated a 101-Gb/s dual-band transmission over 320-km SSMF within only 30-GHz electrical bandwidth, which is highly competitive in both capacity and cost.

  20. Is there radar evidence for liquid water on Mars?

    Science.gov (United States)

    Roth, L. E.

    1984-01-01

    The hypothesis that an extraordinary radar smoothness of a lunar target suggests that ground moisture is rest on the assumption that on the penetration-depth scale, the dielectric constant be an isotropic quantity. In other words, the planet's surface should have no vertical structure. Results of modeling exercises (based on the early lunar two-layer models) conducted to simulate the behavior of radar reflectivity, at S-band, over Solis Lacus, without manipulating the dielectric constant of the base layer (i.e., without adding moisture) are summarized. More sophisticated, explicit, rather than iterative multi-layer models involving dust, duricrust, mollisol, and permafrost are under study. It is anticipated that a paradoxical situation will be reached when each improvement in the model introduces additional ambiguities into the data interpretation.

  1. Space radar image of Mauna Loa, Hawaii

    Science.gov (United States)

    1995-01-01

    This image of the Mauna Loa volcano on the Big Island of Hawaii shows the capability of imaging radar to map lava flows and other volcanic structures. Mauna Loa has erupted more than 35 times since the island was first visited by westerners in the early 1800s. The large summit crater, called Mokuaweoweo Caldera, is clearly visible near the center of the image. Leading away from the caldera (towards top right and lower center) are the two main rift zones shown here in orange. Rift zones are areas of weakness within the upper part of the volcano that are often ripped open as new magma (molten rock) approaches the surface at the start of an eruption. The most recent eruption of Mauna Loa was in March and April 1984, when segments of the northeast rift zones were active. If the height of the volcano was measured from its base on the ocean floor instead of from sea level, Mauna Loa would be the tallest mountain on Earth. Its peak (center of the image) rises more than 8 kilometers (5 miles) above the ocean floor. The South Kona District, known for cultivation of macadamia nuts and coffee, can be seen in the lower left as white and blue areas along the coast. North is toward the upper left. The area shown is 41.5 by 75 kilometers (25.7 by 46.5 miles), centered at 19.5 degrees north latitude and 155.6 degrees west longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/ X-SAR) aboard the space shuttle Endeavour on its 36th orbit on October 2, 1994. The radar illumination is from the left of the image. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted, vertically received); blue represents the C-band (horizontally transmitted, vertically received). The resulting color combinations in this radar image are caused by differences in surface roughness of the lava flows. Smoother flows

  2. Non-Cooperative Air Target Identification Using Radar (l’Identification radar des cibles aeriennes non cooperatives)

    Science.gov (United States)

    1998-11-01

    des techniques tr~s prometteuse pour la detection longue port~e. Les progr~s escompt ~s dans le domaine des techniques radar devraient amener des...cibles fixes, des cibles mobiles ou du fouillis de sol. Sa vocation Le moyen de mesures comprend un radar premiere est d’enrichir les banques de donn6es

  3. Cuerpo(s-espacio(s como objeto(s de intervención política. Lecturas críticas sobre el programa habitacional “Mi Casa, Mi Vida”

    Directory of Open Access Journals (Sweden)

    Pedro Lisdero

    2010-04-01

    Full Text Available Este libro presenta resultados de la investigación titulada “Subjetividades y contextos de pobreza. Deconstrucción de políticas habitacionales en el traslado de familias a nuevas ciudades-barrio de Córdoba”, dirigida por María Eugenia Boito y Ana Levstein.Desde nuestra interpretación, la amplitud de miradas recogidas en artículos individuales y colectivos, encuentra en la problematización de una política pública puntual un campo fructífero donde indagar ciertas relaciones entre sujeto-cuerpo y espacios, que devienen centrales para comprender los procesos de constitución social. La reseña se organiza en función de tres ejes: primero reunimos artículos que se ocupan de las lógicas de funcionamiento de un tipo de intervención estatal en el campo de la pobreza, que reconfigura no solo las posibilidades de movilidad, acción e interacción entre los cuerpos, sino que además afecta las constituciones subjetivas a partir de lo que inaugura la vivencia de la condición habitacional. Un segundo eje se traza alrededor de la indagación de la transformación en los regímenes de sensibilidad atados a la nueva condición habitacional. Finalmente se vincula el juego entre la operatoria del sueño observada por Scribano y la propuesta de recuperar la literalidad como clave de análisis crítico que señalan en su artículo Boito, Espoz e Ibáñez.

  4. CdS{sub x}Te{sub 1-x} ternary semiconductors band gaps calculation using ground state and GW approximations

    Energy Technology Data Exchange (ETDEWEB)

    Kheloufi, Nawal; Bouzid, Abderrazak, E-mail: a_bouzid34@hotmail.com

    2016-06-25

    We present band gap calculations of zinc-blende ternary CdS{sub x}Te{sub 1-x} semiconductors within the standard DFT and quasiparticle calculations employing pseudopotential method. The DFT, the local density approximation (LDA) and the Generalized Gradient Approximation (GGA) based calculations have given very poor results compared to experimental data. The quasiparticle calculations have been investigated via the one-shot GW approximation. The present paper discuses and confirms the effect of inclusion of the semicore states in the cadmium (Cd) pseudopotential. The obtained GW quasiparticle band gap using Cd{sup +20} pseudopotential has been improved compared to the obtained results from the available pseudopotential without the treatment of semicore states. Our DFT and quasiparticle band gap results are discussed and compared to the available theoretical calculations and experimental data. - Graphical abstract: Band gaps improvement concerning the binary and ternary alloys using the GW approximation and Cd{sup 20+} pseudopotential with others levels of approximations (the LDA and GGA approximation employing the Cd{sup 12+} and the LDA within Cd{sup 20+} pseudopotential). - Highlights: • The direct Γ- Γ and indirect Γ- X and Γ- L bands gaps show a nonlinear behavior when S content is enhanced. • The quasiparticle band gap result for the investigated semiconductors is improved using the GW approximation. • All CdS{sub x}Te{sub 1-x} compounds in all compositions range from 0 to 1 are direct band gap semiconductors.

  5. Interface band gap narrowing behind open circuit voltage losses in Cu2ZnSnS4 solar cells

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Palsgaard, Mattias Lau Nøhr; Gunst, Tue

    2017-01-01

    We present evidence that bandgap narrowing at the heterointerface may be a major cause of the large open circuit voltage deficit of Cu2ZnSnS4/CdS solar cells. Bandgap narrowing is caused by surface states that extend the Cu2ZnSnS4valence band into the forbidden gap. Those surface states...... are consistently found in Cu2ZnSnS4, but not in Cu2ZnSnSe4, by first-principles calculations. They do not simply arise from defects at surfaces but are an intrinsic feature of Cu2ZnSnS4 surfaces. By including those states in a device model, the outcome of previously published temperature-dependent open circuit...... voltage measurements on Cu2ZnSnS4 solar cells can be reproduced quantitatively without necessarily assuming a cliff-like conduction band offset with the CdS buffer layer. Our first-principles calculations indicate that Zn-based alternative buffer layers are advantageous due to the ability of...

  6. Change detection in a short time sequence of polarimetric C-band SAR data

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2016-01-01

    in the covariance matrix representation is carried out. The omnibus test statistic and its factorization detect if and when change(s) occur. The technique is demonstrated on airborne EMISAR C-band data but may be applied to ALOS, COSMO-SkyMed, RadarSat-2 Sentinel-1, TerraSAR-X, and Yaogan data also....

  7. DOE's 449 MHz Wind Profiling Radars on the U.S. West Coast: Annual Report for Fiscal Year 2016

    Energy Technology Data Exchange (ETDEWEB)

    Flaherty, Julia E.; Wilczak, J. M.; King, Clark W.; Shaw, William J.; White, A. B.; Ayers, Tom

    2016-09-30

    The three coastal wind profilers and associated meteorological instruments located in Forks, WA, Astoria, OR, and North Bend, OR, provide important observations at high temporal and vertical spatial resolution to characterize the meteorological inflow to the western region of the United States. These instruments have been operating for a year or more, and furnish boundary conditions for the modeling efforts of the WFIP2 project. The data have been delivered to archives at both NOAA and the DOE A2e DAP at a data recovery rate in excess of 98%. Site maintenance activities have been relatively minor, with a few component replacements and repairs to RASS foam. Bird mortality surveys have found no bird nests or carcasses, and the U.S. Fish and Wildlife Service has regularly been provided survey reports. This project represents a successful collaboration between PNNL and NOAA to procure, test, deploy, maintain, and operate three 449 MHz radar wind profilers.

  8. 80 Gbit/s 16-QAM Multicarrier THz Wireless Communication Link in the 400 GHz Band

    DEFF Research Database (Denmark)

    Jia, Shi; Yu, Xianbin; Hu, Hao

    2016-01-01

    We experimentally demonstrate a high-speed multicarrier THz wireless communication system operating in the 400 GHz band. The use of spectrally efficient 16-QAM modulation and broadband THz transceivers enable link data rates up to 80 Gbit/s....

  9. Demonstration of 352 Gbit/s Photonically-enabled D-Band Wireless Delivery in one 2x2 MIMO System

    DEFF Research Database (Denmark)

    Puerta Ramírez, Rafael; Yu, Jianjun; Li, Xinying

    2017-01-01

    First demonstration of photonically-enabled independent side-bands D-Band wireless transmission up to 352 Gbit/s with a BER below 3.8×10-3. These results were achieved by means of advanced DSP and antenna polarization multiplexing (2x2 MIMO)....

  10. Sulfur L{sub 2,3} soft-x-ray fluorescence of CdS and ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    The II-VI sulfur compounds CdS and ZnS have important electro-optics applications. In addition, they have well characterized and relatively simple structures so that they are good candidates for theoretical model development in solid-state physics. Some experimental results on density of states have been reported, mostly determined from photoemission measurements, and theoretical calculations are available for both materials. Nevertheless the electronic properties of these elements are still not completely understood. It has been established that the d-bands, derived from Cd or Zn, lie in a subband gap between a lower valence band (LVB) derived from the S 3s orbital and an upper valence band (UVB) derived from the 3p states of S and the 4(3)s states of Cd(Zn). The locations of these bands within the gap disagree with the best available calculations, however. The principal problem is that experimental photoemission measurements locate the d-bands about 2 eV lower in the band gap than the best available calculations. Some authors argue that the hole in the d-band in the final state of the photoemission process increases the binding of the d-electrons. In any case, band gaps, band widths and the precise location of d-bands are important parameters for comparing experiment and theory, and no current calculations give good agreement with all of these parameters. Moreover, photoemission data does not adequately define all of these experimental parameters, because the d-state photoemission dominates that from s and p states and sample charging effects can modify the energy of emitted electrons. The authors report photon excited soft x-ray fluorescence (SXF) S L{sub 2,3} spectra from CdS and ZnS. Using excitation between the L{sub 2} and L{sub 3} thresholds, the L{sub 2} spectrum is suppressed, which permits the authors to accurately determine features of the UVB and LVB as well as the placement of the Cd(Zn) d-bands between the UVB and LVB.

  11. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    Science.gov (United States)

    Petersen, Walt; Krajewski, Witek; Wolff, David; Gatlin, Patrick

    2015-04-01

    The Global Precipitation Measurement (GPM) Mission Iowa Flood Studies (IFloodS) campaign was conducted in central and northeastern Iowa during the months of April-June, 2013. Specific science objectives for IFloodS included quantification of uncertainties in satellite and ground-based estimates of precipitation, 4-D characterization of precipitation physical processes and associated parameters (e.g., size distributions, water contents, types, structure etc.), assessment of the impact of precipitation estimation uncertainty and physical processes on hydrologic predictive skill, and refinement of field observations and data analysis approaches as they pertain to future GPM integrated hydrologic validation and related field studies. In addition to field campaign archival of raw and processed satellite data (including precipitation products), key ground-based platforms such as the NASA NPOL S-band and D3R Ka/Ku-band dual-polarimetric radars, University of Iowa X-band dual-polarimetric radars, a large network of paired rain gauge platforms, and a large network of 2D Video and Parsivel disdrometers were deployed. In something of a canonical approach, the radar (NPOL in particular), gauge and disdrometer observational assets were deployed to create a consistent high-quality distributed (time and space sampling) radar-based ground "reference" rainfall dataset, with known uncertainties, that could be used for assessing the satellite-based precipitation products at a range of space/time scales. Subsequently, the impact of uncertainties in the satellite products could be evaluated relative to the ground-benchmark in coupled weather, land-surface and distributed hydrologic modeling frameworks as related to flood prediction. Relative to establishing the ground-based "benchmark", numerous avenues were pursued in the making and verification of IFloodS "reference" dual-polarimetric radar-based rain maps, and this study documents the process and results as they pertain specifically

  12. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    Science.gov (United States)

    Petersen, Walter; Wolff, David; Krajewski, Witek; Gatlin, Patrick

    2015-01-01

    The Global Precipitation Measurement (GPM) Mission Iowa Flood Studies (IFloodS) campaign was conducted in central and northeastern Iowa during the months of April-June, 2013. Specific science objectives for IFloodS included quantification of uncertainties in satellite and ground-based estimates of precipitation, 4-D characterization of precipitation physical processes and associated parameters (e.g., size distributions, water contents, types, structure etc.), assessment of the impact of precipitation estimation uncertainty and physical processes on hydrologic predictive skill, and refinement of field observations and data analysis approaches as they pertain to future GPM integrated hydrologic validation and related field studies. In addition to field campaign archival of raw and processed satellite data (including precipitation products), key ground-based platforms such as the NASA NPOL S-band and D3R Ka/Ku-band dual-polarimetric radars, University of Iowa X-band dual-polarimetric radars, a large network of paired rain gauge platforms, and a large network of 2D Video and Parsivel disdrometers were deployed. In something of a canonical approach, the radar (NPOL in particular), gauge and disdrometer observational assets were deployed to create a consistent high-quality distributed (time and space sampling) radar-based ground "reference" rainfall dataset, with known uncertainties, that could be used for assessing the satellite-based precipitation products at a range of space/time scales. Subsequently, the impact of uncertainties in the satellite products could be evaluated relative to the ground-benchmark in coupled weather, land-surface and distributed hydrologic modeling frameworks as related to flood prediction. Relative to establishing the ground-based "benchmark", numerous avenues were pursued in the making and verification of IFloodS "reference" dual-polarimetric radar-based rain maps, and this study documents the process and results as they pertain specifically

  13. Cross-polarization microwave radar return at severe wind conditions: laboratory model and geophysical model function.

    Science.gov (United States)

    Troitskaya, Yuliya; Abramov, Victor; Ermoshkin, Alexey; Zuikova, Emma; Kazakov, Vassily; Sergeev, Daniil; Kandaurov, Alexandr

    2014-05-01

    Satellite remote sensing is one of the main techniques of monitoring severe weather conditions over the ocean. The principal difficulty of the existing algorithms of retrieving wind based on dependence of microwave backscattering cross-section on wind speed (Geophysical Model Function, GMF) is due to its saturation at winds exceeding 25 - 30 m/s. Recently analysis of dual- and quad-polarization C-band radar return measured from satellite Radarsat-2 suggested that the cross-polarized radar return has much higher sensitivity to the wind speed than co-polarized back scattering [1] and conserved sensitivity to wind speed at hurricane conditions [2]. Since complete collocation of these data was not possible and time difference in flight legs and SAR images acquisition was up to 3 hours, these two sets of data were compared in [2] only statistically. The main purpose of this paper is investigation of the functional dependence of cross-polarized radar cross-section on the wind speed in laboratory experiment. Since cross-polarized radar return is formed due to scattering at small-scale structures of the air-sea interface (short-crested waves, foam, sprays, etc), which are well reproduced in laboratory conditions, then the approach based on laboratory experiment on radar scattering of microwaves at the water surface under hurricane wind looks feasible. The experiments were performed in the Wind-wave flume located on top of the Large Thermostratified Tank of the Institute of Applied Physics, where the airflow was produced in the flume with the straight working part of 10 m and operating cross section 0.40?0.40 sq. m, the axis velocity can be varied from 5 to 25 m/s. Microwave measurements were carried out by a coherent Doppler X-band (3.2 cm) scatterometer with the consequent receive of linear polarizations. Experiments confirmed higher sensitivity to the wind speed of the cross-polarized radar return. Simultaneously parameters of the air flow in the turbulent boundary layer

  14. Use of the X-Band Radar to Support the Detection of In-Flight Icing Hazards by the NASA Icing Remote Sensing System

    Science.gov (United States)

    Serke, David J.; Politovich, Marcia K.; Reehorst, Andrew L.; Gaydos, Andrew

    2009-01-01

    The Alliance Icing Research Study-II (AIRS-II) field program was conducted near Montreal, Canada during the winter of 2003. The NASA Icing Remote Detection System (NIRSS) was deployed to detect in-flight icing hazards and consisted of a vertically pointing multichannel radiometer, a ceilometer and an x-band cloud radar. The radiometer was used to derive atmospheric temperature soundings and integrated liquid water, while the ceilometer and radar were used only to define cloud boundaries. The purpose of this study is to show that the radar reflectivity profiles from AIRS-II case studies could be used to provide a qualitative icing hazard.

  15. Cross-validation Methodology between Ground and GPM Satellite-based Radar Rainfall Product over Dallas-Fort Worth (DFW) Metroplex

    Science.gov (United States)

    Chen, H.; Chandrasekar, V.; Biswas, S.

    2015-12-01

    Over the past two decades, a large number of rainfall products have been developed based on satellite, radar, and/or rain gauge observations. However, to produce optimal rainfall estimation for a given region is still challenging due to the space time variability of rainfall at many scales and the spatial and temporal sampling difference of different rainfall instruments. In order to produce high-resolution rainfall products for urban flash flood applications and improve the weather sensing capability in urban environment, the center for Collaborative Adaptive Sensing of the Atmosphere (CASA), in collaboration with National Weather Service (NWS) and North Central Texas Council of Governments (NCTCOG), has developed an urban radar remote sensing network in DFW Metroplex. DFW is the largest inland metropolitan area in the U.S., that experiences a wide range of natural weather hazards such as flash flood and hailstorms. The DFW urban remote sensing network, centered by the deployment of eight dual-polarization X-band radars and a NWS WSR-88DP radar, is expected to provide impacts-based warning and forecasts for benefit of the public safety and economy. High-resolution quantitative precipitation estimation (QPE) is one of the major goals of the development of this urban test bed. In addition to ground radar-based rainfall estimation, satellite-based rainfall products for this area are also of interest for this study. Typical example is the rainfall rate product produced by the Dual-frequency Precipitation Radar (DPR) onboard Global Precipitation Measurement (GPM) Core Observatory satellite. Therefore, cross-comparison between ground and space-based rainfall estimation is critical to building an optimal regional rainfall system, which can take advantages of the sampling differences of different sensors. This paper presents the real-time high-resolution QPE system developed for DFW urban radar network, which is based upon the combination of S-band WSR-88DP and X-band

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

    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...

  17. Attenuation-difference radar tomography: results of a multiple-plane experiment at the U.S. Geological Survey Fractured-Rock Research Site, Mirror Lake, New Hampshire

    Science.gov (United States)

    Lane, J.W.; Day-Lewis, F. D.; Harris, J.M.; Haeni, F.P.; Gorelick, S.M.

    2000-01-01

    Attenuation-difference, borehole-radar tomography was used to monitor a series of sodium chloride tracer injection tests conducted within the FSE, wellfield at the U.S. Geological Survey Fractured-Rock Hydrology Research Site in Grafton County, New Hampshire, USA. Borehole-radar tomography surveys were conducted using the sequential-scanning and injection method in three boreholes that form a triangular prism of adjoining tomographic image planes. Results indicate that time-lapse tomography methods provide high-resolution images of tracer distribution in permeable zones.

  18. 150-MW S-Band klystron program at the Stanford Linear Accelerator Center

    Energy Technology Data Exchange (ETDEWEB)

    Sprehn, D.; Caryotakis, G.; Phillips, R.M. [Stanford Linear Accelerator Center, Stanford Univ., Stanford, CA (United States)

    1997-04-01

    Two S-Band klystrons operating at 150 MW have been designed, fabricated and tested at the Stanford Linear Accelerator Center (SLAC) during the past two years for use in an experimental accelerator at Deutsches Elektronen Synchrotron (DESY) in Hamburg, Germany. Both klystrons operate at the design power, 60 Hz repetition rate, 3 {mu}s pulsewidth, with an efficiency > 40%, and agreement between the experimental results and simulations is excellent. The 535 kV, 700 A electron gun was tested by constructing a solenoidal focused beam-stick which identified a source of oscillation, subsequently engineered out of the klystron guns. Design of the beam-stick and the two klystrons is discussed, along with observation and suppression of spurious oscillations. Differences in design and the resulting performance of the klystrons is emphasized. (author)

  19. Size-dependent and intra-band photoluminescence of NiS{sub 2} nano-alloys synthesized by microwave assisted hydrothermal technique

    Energy Technology Data Exchange (ETDEWEB)

    Linganiso, Ella Cebisa [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001 (South Africa); Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Johannesburg, Wits 2050 (South Africa); Mhlanga, Sabelo Dalton; Coville, Neil John [Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Johannesburg, Wits 2050 (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Johannesburg, Wits 2050 (South Africa); Mwakikunga, Bonex Wakufwa, E-mail: bmwakikunga@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001 (South Africa); Department of Physics and Biochemical Sciences, University of Malawi, The Polytechnic, Private Bag 303, Chichiri, Blantyre 3 (Malawi)

    2013-03-05

    Graphical abstract: Unexpected ultra-violet (UV) emission as well as near infra-red (IR) emissions were attributed to intra-band energy state transitions that occur as a result of the porous structure of the material. Enhanced UV and near IR PL emissions due to the smaller crystallite size of the capped NiS{sub 2} nanostructures was also observed. Band energy and local density of states calculation for NiS{sub 2} were used to support the experimentally observed luminescence results. The luminescence features at wavelengths of 400 nm (3.10 eV), 428 nm (2.90 eV), 447 nm (2.77 eV) and 464 nm (2.67) can be attributed to some of those electrons de-exciting from S (3p) levels down to the Ni (3d) (blue to UV emission) whereas those features at wavelengths of 710 nm (1.75 eV), 751 nm (1.65 eV), 754 nm (1.64 eV) [NiS{sub 2}/HDA-capped NiS{sub 2}] and 784 nm (1.58 eV) respectively seem to result from de-excitations between either Ni(3d) or S (3s, 3p) levels and Ni–S hybridization levels (red to near IR emission). Highlights: ► Rapid solid state alloying of Ni and S from their liquid state precursor by microwaves. ► New photoluminescence data of NiS{sub 2} system. ► Unexpected luminescence in the UV–Visible and near IR ranges for such a metal matrix alloy. ► Explanation of NiS{sub 2} photoluminescence from ab initio calculations by electronic energy band structure and density of states. -- Abstract: Synthesis of nickel disulfide (NiS{sub 2}) nano-alloys capped and uncapped with hexadecylamine (HDA) was carried out. A cubic phase NiS{sub 2} formation was confirmed by X-ray diffraction (XRD) analysis. An average crystallite size of 35 nm was obtained for the uncapped nanostructures and 9 nm was obtained for the capped nanostructures estimated using the Scherrer equation. Unexpected ultra-violet (UV) emission as well as near infrared (IR) emissions were attributed to intra-band energy state transitions that occur as a result of the porous structure of the material

  20. Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band

    International Nuclear Information System (INIS)

    Jang, Hong-Kyu; Lee, Won-Jun; Kim, Chun-Gon

    2011-01-01

    In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass/epoxy composite materials, which are typically used for load-bearing structures, such as aircraft and other vehicles. Then, CP EBG patterns were also designed that had a 90% electromagnetic (EM) wave absorbing performance within the X-band (8.2–12.4 GHz). Finally, the CP EBG patterns were printed on the top surface of the microstrip patch antenna. The measured radar absorbing performance of the fabricated patch antenna showed that the frontal RCS of the antenna declined by nearly 95% at 10 GHz frequency while the CP EBG patterns had almost no effect on the antenna's performance

  1. A model for calculating expected performance of the Apollo unified S-band (USB) communication system

    Science.gov (United States)

    Schroeder, N. W.

    1971-01-01

    A model for calculating the expected performance of the Apollo unified S-band (USB) communication system is presented. The general organization of the Apollo USB is described. The mathematical model is reviewed and the computer program for implementation of the calculations is included.

  2. Surface Floating 2D Bands in Layered Nonsymmorphic Semimetals: ZrSiS and Related Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Topp, Andreas; Queiroz, Raquel; Grüneis, Andreas; Müchler, Lukas; Rost, Andreas W.; Varykhalov, Andrei; Marchenko, Dmitry; Krivenkov, Maxim; Rodolakis, Fanny; McChesney, Jessica L.; Lotsch, Bettina V.; Schoop, Leslie M.; Ast, Christian R.

    2017-12-01

    In this work, we present a model of the surface states of nonsymmorphic semimetals. These are derived from surface mass terms that lift the high degeneracy imposed in the band structure by the nonsymmorphic bulk symmetries. Reflecting the reduced symmetry at the surface, the bulk bands are strongly modified. This leads to the creation of two-dimensional floating bands, which are distinct from Shockley states, quantum well states or topologically protected surface states. We focus on the layered semimetal ZrSiS to clarify the origin of its surface states. We demonstrate an excellent agreement between DFT calculations and ARPES measurements and present an effective four-band model in which similar surface bands appear. Finally, we emphasize the role of the surface chemical potential by comparing the surface density of states in samples with and without potassium coating. Our findings can be extended to related compounds and generalized to other crystals with nonsymmorphic symmetries.

  3. Development of new S-band RF window for stable high-power operation in linear accelerator RF system

    Science.gov (United States)

    Joo, Youngdo; Lee, Byung-Joon; Kim, Seung-Hwan; Kong, Hyung-Sup; Hwang, Woonha; Roh, Sungjoo; Ryu, Jiwan

    2017-09-01

    For stable high-power operation, a new RF window is developed in the S-band linear accelerator (Linac) RF systems of the Pohang Light Source-II (PLS-II) and the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL). The new RF window is designed to mitigate the strength of the electric field at the ceramic disk and also at the waveguide-cavity coupling structure of the conventional RF window. By replacing the pill-box type cavity in the conventional RF window with an overmoded cavity, the electric field component perpendicular to the ceramic disk that caused most of the multipacting breakdowns in the ceramic disk was reduced by an order of magnitude. The reduced electric field at the ceramic disk eliminated the Ti-N coating process on the ceramic surface in the fabrication procedure of the new RF window, preventing the incomplete coating from spoiling the RF transmission and lowering the fabrication cost. The overmoded cavity was coupled with input and output waveguides through dual side-wall coupling irises to reduce the electric field strength at the waveguide-cavity coupling structure and the possibility of mode competitions in the overmoded cavity. A prototype of the new RF window was fabricated and fully tested with the Klystron peak input power, pulse duration and pulse repetition rate of 75 MW, 4.5 μs and 10 Hz, respectively, at the high-power test stand. The first mass-produced new RF window installed in the PLS-II Linac is running in normal operation mode. No fault is reported to date. Plans are being made to install the new RF window to all S-band accelerator RF modules of the PLS-II and PAL-XFEL Linacs. This new RF window may be applied to the output windows of S-band power sources like Klystron as wells as the waveguide windows of accelerator facilities which operate in S-band.

  4. A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data

    Directory of Open Access Journals (Sweden)

    Fulong Chen

    2014-12-01

    Full Text Available With the development of Synthetic Aperture Radar (SAR in terms of multi-band, multi-polarization and high-resolution data, space radar remote sensing for archaeology has become a potential field for research. Nevertheless, the archaeological detection capability of this technology has so far not been fully assessed. This paper is a pioneering effort to assess the potential of satellite SAR X-band data in the detection of archaeological marks. We focus on the results obtained from a collaborative contribution jointly carried out by archaeologists and remote sensing experts in order to test the use of COSMO-SkyMed data in different contexts and environmental conditions. The methodological approaches we adopted are based on two different feature-enhancement procedures: (i multi-temporal analysis performed to reduce noise and highlight archaeological marks; (ii single-date analysis to assess the ability of the single SAR scene to detect archaeological features like with optical remote sensing. Results from multi-temporal data analysis, conducted using 40 scenes from COSMO-SkyMed X-band Stripmap data (27 February to 17 October 2013, enable us to detect unknown archaeological crop, soil, and shadow marks representing Luoyang city, dating from the Eastern-Han to Northern-Wei Dynasties. Single-date analyses were conducted using COSMO-SkyMed Spotlight scenes acquired for Sabratha (Libya and Metapontum (southern Italy. These case studies were selected because they are characterized by diverse superficial conditions (desert and Mediterranean area and archaeological marks (crop, soil and shadow. The results we obtained for both of them show that even a single SAR X-band acquisition is a feasible and effective approach for archaeological prospection. Overall, the methodological approach adopted demonstrated that both multi-temporal and single-date analysis are suitable for the enhancement of archaeological and palaeoenvironmental features.

  5. SEGMENTATION OF POLARIMETRIC SAR IMAGES USIG WAVELET TRANSFORMATION AND TEXTURE FEATURES

    Directory of Open Access Journals (Sweden)

    A. Rezaeian

    2015-12-01

    Full Text Available Polarimetric Synthetic Aperture Radar (PolSAR sensors can collect useful observations from earth’s surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT. Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  6. Intensive probing of clear air convective fields by radar and instrumented drone aircraft.

    Science.gov (United States)

    Rowland, J. R.

    1972-01-01

    Clear air convective fields were probed in three summer experiments (1969, 1970, and 1971) on an S-band monopulse tracking radar at Wallops Island, Virginia, and a drone aircraft with a takeoff weight of 5.2 kg, wingspan of 2.5 m, and cruising glide speed of 10.3 m/sec. The drone was flown 23.2 km north of the radar and carried temperature, pressure/altitude, humidity, and vertical and airspeed velocity sensors. Extensive time-space convective field data were obtained by taking a large number of RHI and PPI pictures at short intervals of time. The rapidly changing overall convective field data obtained from the radar could be related to the meteorological information telemetered from the drone at a reasonably low cost by this combined technique.

  7. Composition-tuned band gap energy and refractive index in GaS{sub x}Se{sub 1−x} layered mixed crystals

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Mehmet, E-mail: mehmet.isik@atilim.edu.tr [Department of Electrical and Electronics Engineering, Atilim University, 06836, Ankara (Turkey); Gasanly, Nizami [Department of Physics, Middle East Technical University, 06800, Ankara (Turkey); Virtual International Scientific Research Centre, Baku State University, 1148, Baku (Azerbaijan)

    2017-04-01

    Transmission and reflection measurements on GaS{sub x}Se{sub 1−x} mixed crystals (0 ≤ x ≤ 1) were carried out in the 400–1000 nm spectral range. Band gap energies of the studied crystals were obtained using the derivative spectra of transmittance and reflectance. The compositional dependence of band gap energy revealed that as sulfur (selenium) composition is increased (decreased) in the mixed crystals, band gap energy increases quadratically from 1.99 eV (GaSe) to 2.55 eV (GaS). Spectral dependencies of refractive indices of the mixed crystals were plotted using the reflectance spectra. It was observed that refractive index decreases nearly in a linear behavior with increasing band gap energy for GaS{sub x}Se{sub 1−x} mixed crystals. Moreover, the composition ratio of the mixed crystals was obtained from the energy dispersive spectroscopy measurements. The atomic compositions of the studied crystals are well-matched with composition x increasing from 0 to 1 by intervals of 0.25. - Highlights: • Transmission and reflection experiments were performed on GaS{sub x}Se{sub 1−x} mixed crystals. • Derivative spectra of transmittance and reflectance were used for analyses. • Compositional dependence of band gap energy and refractive index were reported.

  8. Cuerpo(s-espacio(s como objeto(s de intervención política. Lecturas críticas sobre el programa habitacional “Mi Casa, Mi Vida”

    Directory of Open Access Journals (Sweden)

    Pedro Lisdero

    2010-04-01

    Full Text Available Este libro presenta resultados de la investigación titulada “Subjetividades y contextos de pobreza. Deconstrucción de políticas habitacionales en el traslado de familias a nuevas ciudades-barrio de Córdoba”, dirigida por María Eugenia Boito y Ana Levstein. Desde nuestra interpretación, la amplitud de miradas recogidas en artículos individuales y colectivos, encuentra en la problematización de una política pública puntual un campo fructífero donde indagar ciertas relaciones entre sujeto-cuerpo y espacios, que devienen centrales para comprender los procesos de constitución social. La reseña se organiza en función de tres ejes: primero reunimos artículos que se ocupan de las lógicas de funcionamiento de un tipo de intervención estatal en el campo de la pobreza, que reconfigura no solo las posibilidades de movilidad, acción e interacción entre los cuerpos, sino que además afecta las constituciones subjetivas a partir de lo que inaugura la vivencia de la condición habitacional. Un segundo eje se traza alrededor de la indagación de la transformación en los regímenes de sensibilidad atados a la nueva condición habitacional. Finalmente se vincula el juego entre la operatoria del sueño observada por Scribano y la propuesta de recuperar la literalidad como clave de análisis crítico que señalan en su artículo Boito, Espoz e Ibáñez. Fecha de recepción: 31 de marzo de 2010. Fecha de aceptación: 18 de abril de 2010.

  9. Measurement of IR atmospheric band dayglow by S-520-4 rocket

    International Nuclear Information System (INIS)

    Makino, Tadao; Yamamoto, Hiromasa; Sekiguchi, Hiroyuki

    1984-01-01

    The measurement of IR atmospheric band dayglow was made by rocket S-520-4 flown from Uchinoura at 1000 JST on Sept. 5, 1981. The instrument loaded on the rocket was the same type as the one loaded on EXOS-C satellite which will be launched in 1984 in order to observe the mesospheric ozone. This rocket experiment was performed for the purpose of testing the functions of this instrument in flight. The 1.27 μm filter radiometer consisted of three plane mirros, a camera lens, a chopper and a PbS detector array. The PbS array (4x5=20 elements) was operated at about -4 0 C with a thermoelectric cooler. We obtained the following results from the rocket experiment: (i) this instrument worked well during the flight, (ii) the intensities of the solar radiation scattered by the sea and clouds were obtained at 1.27 μm, and (iii) the baffle designed to permit the daytime measurement of the atmospheric emission could attenuate the off-axis radiation as weak as possible. The altitude distribution of the daytime mesospheric ozone density derived from the downleg data was in agreement with the previous profile obtained in twilight condition. (author)

  10. Evaluating and managing Cold War era historic properties : the cultural significance of U.S. Air Force defensive radar systems.

    Energy Technology Data Exchange (ETDEWEB)

    Whorton, M.

    1999-01-20

    Aircraft and later missile radar early warning stations played an important role in the Cold War. They are associated with important technological, social, political, and military themes of the Cold War and are worthy of preservation. The scope and scale of these systems make physical preservation impractical, but the U.S. Air Force program of historical evaluation and documentation of these systems will provide valuable information to future generations studying this historic period.

  11. MAJOR SOURCE OF SIDE-LOOKING AIRBORNE RADAR IMAGERY FOR RESEARCH AND EXPLORATION: THE U. S. GEOLOGICAL SURVEY.

    Science.gov (United States)

    Kover, Allan N.; Jones, John Edwin; ,

    1985-01-01

    The US Geological Survey (USGS) instituted a program in 1980 to acquire side-looking airbore radar (SLAR) data and make these data readily available to the public in a mosaic format comparable to the USGS 1:250,000-scale topographic map series. The SLAR data are also available as strip images at an acquisition scale of 1:250,000 or 1:400,000 (depending on the acquisition system), as a variety of print products and indexes, and in a limited amount in digital form on computer compatible tapes. Three different commercial X-band (3-cm) systems were used to acquire the imagery for producing the mosaics.

  12. Wide-band fanned-out supercontinuum source covering O-, E-, S-, C-, L- and U-bands

    Science.gov (United States)

    Ahmad, H.; Latif, A. A.; Awang, N. A.; Zulkifli, M. Z.; Thambiratnam, K.; Ghani, Z. A.; Harun, S. W.

    2012-10-01

    A wide-band supercontinuum source generated by mode-locked pulses injected into a Highly Non-Linear Fiber (HNLF) is proposed and demonstrated. A 49 cm long Bismuth-Erbium Doped Fiber (Bi-EDF) pumped by two 1480 nm laser diodes acts as the active gain medium for a ring fiber laser, from which mode-locked pulses are obtained using the Non-Polarization Rotation (NPR) technique. The mode-locked pulses are then injected into a 100 m long HLNF with a dispersion of 0.15 ps/nm km at 1550 nm to generate a supercontinuum spectrum spanning from 1340 nm to more than 1680 nm with a pulse width of 0.08 ps and an average power of -17 dBm. The supercontinuum spectrum is sliced using a 24 channel Arrayed Waveguide Grating (AWG) with a channel spacing of 100 GHz to obtain a fanned-out laser output covering the O-, E-, S-, C-, L- and U-bands. The lasing wavelengths obtained have an average pulse width of 9 ps with only minor fluctuations and a mode-locked repetition rate of 40 MHz, and is sufficiently stable to be used in a variety of sensing and communication applications, most notably as cost-effective sources for Fiber-to-the-Home (FTTH) networks.

  13. GPM GROUND VALIDATION NOAA S-BAND PROFILER RAW DATA NETCDF FORMAT MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The S-band Profiler Raw dataset was saved in two data formats: netCDF anda proprietary Vaisala SPC format. The numeric values in both formats are exactly the same....

  14. A simulation study of the effects of land cover and crop type on sensing soil moisture with an orbital C-band radar

    Science.gov (United States)

    Dobson, M. C.; Ulaby, F. T.; Moezzi, S.; Roth, E.

    1983-01-01

    Simulated C-band radar imagery for a 124-km by 108-km test site in eastern Kansas is used to classify soil moisture. Simulated radar resolutions are 100 m by 100 m, 1 km by 1 km, and 3 km by 3 km, and each is processed using more than 23 independent samples. Moisture classification errors are examined as a function of land-cover distribution, field-size distribution, and local topographic relief for the full test site and also for subregions of cropland, urban areas, woodland, and pasture/rangeland. Results show that a radar resolution of 100 m by 100 m yields the most robust classification accuracies.

  15. Underlying topography extraction over forest areas from multi-baseline PolInSAR data

    Science.gov (United States)

    Fu, Haiqiang; Zhu, Jianjun; Wang, Changcheng; Li, Zhiwei

    2017-11-01

    In this paper, the digital elevation model (DEM) for a forest area is extracted from multi-baseline (MB) polarimetric interferometric synthetic aperture radar (PolInSAR) data. On the basis of the random-volume-over-ground (RVoG) model, the weighted complex least-squares adjustment (WCLSA) method is proposed for the ground phase estimation, so that the MB PolInSAR observations can be constrained by a generalized observation function and the observation contribution to the solution can be adjusted by a weighting strategy. A baseline length weighting strategy is then adopted to syncretize the DEMs estimated with the ground phases. The results of the simulated experiment undertaken in this study demonstrate that the WCLSA method is sensitive to the number of redundant observations and can adjust the contributions of the different observations. We also applied the WCLSA method to E-SAR L- and P-band MB PolInSAR data from the Krycklan River catchment in Northern Sweden. The results show that the two extracted DEMs are in close agreement with the Light Detection and Ranging (Lidar) DEM, with root-mean-square errors of 3.54 and 3.16 m. The DEM vertical error is correlated with the terrain slope and ground-cover condition, but not with the forest height.

  16. A 7MeV S-Band 2998MHz Variable Pulse Length Linear Accelerator System

    CERN Document Server

    Hernandez, Michael; Mishin, Andrey V; Saverskiy, Aleksandr J; Skowbo, Dave; Smith, Richard

    2005-01-01

    American Science and Engineering High Energy Systems Division (AS&E HESD) has designed and commissioned a variable pulse length 7 MeV electron accelerator system. The system is capable of delivering a 7 MeV electron beam with a pulse length of 10 nS FWHM and a peak current of 1 ampere. The system can also produce electron pulses with lengths of 20, 50, 100, 200, 400 nS and 3 uS FWHM with corresponding lower peak currents. The accelerator system consists of a gridded electron gun, focusing coil, an electrostatic deflector system, Helmholtz coils, a standing wave side coupled S-band linac, a 2.6 MW peak power magnetron, an RF circulator, a fast toroid, vacuum system and a PLC/PC control system. The system has been operated at repetition rates up to 250pps. The design, simulations and experimental results from the accelerator system are presented in this paper.

  17. Basic study for tsunami detection with DBF ocean radar

    International Nuclear Information System (INIS)

    Sakai, Shin'ichi; Matsuyama, Masafumi; Okuda, Kouzou; Uehara, Fumihiro

    2015-01-01

    To develop early tsunami warning system utilizing ocean radars, the evaluation of the variety of measuring coverage and data accuracy is indispensable in real oceans. The field observation was carried out at 5 minutes interval with two digital beam forming ocean radars with VHF band from 2012 to 2014 in the sea of Enshu. The high data acquisition areas are found in the extent of 17 km off the coast on a hill site and of 13 km on a low ground site. The measured current by the ocean radar were well correlated with that by the current-meter in the depth of 2 m near the coast with the correlation coefficient of ∼0.6. It is inferred that the main factor of difference in both data sets was due to the presence of wind-driven current through the multi-regression analysis with both current data and wind data. In addition, the order of the temporal current deviations as to the representative time-scale of one hour is about 5 cm/s under the ordinary sea conditions, which suggest that ocean radars could sufficiently detect the current deviation due to grant tsunami. (author)

  18. Development of Coatings for Radar Absorbing Materials at X-band

    Science.gov (United States)

    Kumar, Abhishek; Singh, Samarjit

    2018-03-01

    The present review gives a brief account on some of the technical features of radar absorbing materials (RAMs). The paper has been presented with a concentrated approach towards the material aspects for achieving enhanced radar absorption characteristics for its application as a promising candidate in stealth technology and electromagnetic interference (EMI) minimization problems. The effect of metal particles doping/dispersion in the ferrites and dielectrics has been discussed for obtaining tunable radar absorbing characteristics. A short theoretical overview on the development of absorber materials, implementation of genetic algorithm (GA) in multi-layering and frequency selective surfaces (FSSs) based multi-layer has also been presented for the development of radar absorbing coatings for achieving better absorption augmented with broadband features in order to counter the radar detection systems.

  19. The formation of α-phase SnS nanorods by PVP assisted polyol synthesis: Phase stability, micro structure, thermal stability and defects induced energy band transitions

    Energy Technology Data Exchange (ETDEWEB)

    Baby, Benjamin Hudson; Mohan, D. Bharathi, E-mail: d.bharathimohan@gmail.com

    2017-05-01

    We report the formation of single phase of SnS nanostructure through PVP assisted polyol synthesis by varying the source concentration ratio (Sn:S) from 1:1M to 1:12M. The effect of PVP concentration and reaction medium towards the preparation of SnS nanostructure is systematically studied through confocal Raman spectrometer, X-ray diffraction, thermogravimetry analysis, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis–NIR absorption and fluorescence spectrophotometers. The surface morphology of SnS nanostructure changes from nanorods to spherical shape with increasing PVP concentration from 0.15M to 0.5M. Raman analysis corroborates that Raman active modes of different phases of Sn-S are highly active when Raman excitation energy is slightly greater than the energy band gap of the material. The presence of intrinsic defects and large number of grain boundaries resulted in an improved thermal stability of 20 °C during the phase transition of α-SnS. Band gap calculation from tauc plot showed the direct band gap of 1.5 eV which is attributed to the single phase of SnS, could directly meet the requirement of an absorber layer in thin film solar cells. Finally, we proposed an energy band diagram for as synthesized single phase SnS nanostructure based on the experimental results obtained from optical studies showing the energy transitions attributed to band edge transition and also due to the presence of intrinsic defects. - Highlights: • PVP stabilizes the orthorhombic (α) phase of SnS. • Optical band gap of P type SnS tuned by PVP for photovoltaic applications. • The formation of Sn rich SnS phase is investigated through XPS analysis. • Intrinsic defects enhance the thermal stability of α-SnS. • The feasibility of energy transition liable to point defects is discussed.

  20. Per-point and per-field contextual classification of multipolarization and multiple incidence angle aircraft L-band radar data

    Science.gov (United States)

    Hoffer, Roger M.; Hussin, Yousif Ali

    1989-01-01

    Multipolarized aircraft L-band radar data are classified using two different image classification algorithms: (1) a per-point classifier, and (2) a contextual, or per-field, classifier. Due to the distinct variations in radar backscatter as a function of incidence angle, the data are stratified into three incidence-angle groupings, and training and test data are defined for each stratum. A low-pass digital mean filter with varied window size (i.e., 3x3, 5x5, and 7x7 pixels) is applied to the data prior to the classification. A predominately forested area in northern Florida was the study site. The results obtained by using these image classifiers are then presented and discussed.

  1. Using Ground Targets to Validate S-NPP VIIRS Day-Night Band Calibration

    Science.gov (United States)

    Chen, Xuexia; Wu, Aisheng; Xiong, Xiaoxiong; Lei, Ning; Wang, Zhipeng; Chiang, Kwofu

    2016-01-01

    In this study, the observations from S-NPP VIIRS Day-Night band (DNB) and Moderate resolution bands (M bands) of Libya 4 and Dome C over the first four years of the mission are used to assess the DNB low gain calibration stability. The Sensor Data Records produced by NASA Land Product Evaluation and Algorithm Testing Element (PEATE) are acquired from nearly nadir overpasses for Libya 4 desert and Dome C snow surfaces. A kernel-driven bidirectional reflectance distribution function (BRDF) correction model is used for both Libya 4 and Dome C sites to correct the surface BRDF influence. At both sites, the simulated top-of-atmosphere (TOA) DNB reflectances based on SCIAMACHY spectral data are compared with Land PEATE TOA reflectances based on modulated Relative Spectral Response (RSR). In the Libya 4 site, the results indicate a decrease of 1.03% in Land PEATE TOA reflectance and a decrease of 1.01% in SCIAMACHY derived TOA reflectance over the period from April 2012 to January 2016. In the Dome C site, the decreases are 0.29% and 0.14%, respectively. The consistency between SCIAMACHY and Land PEATE data trends is good. The small difference between SCIAMACHY and Land PEATE derived TOA reflectances could be caused by changes in the surface targets, atmosphere status, and on-orbit calibration. The reflectances and radiances of Land PEATE DNB are also compared with matching M bands and the integral M bands based on M4, M5, and M7. The fitting trends of the DNB to integral M bands ratios indicate a 0.75% decrease at the Libya 4 site and a 1.89% decrease at the Dome C site. Part of the difference is due to an insufficient number of sampled bands available within the DNB wavelength range. The above results indicate that the Land PEATE VIIRS DNB product is accurate and stable. The methods used in this study can be used on other satellite instruments to provide quantitative assessments for calibration stability.

  2. Using Ground Targets to Validate S-NPP VIIRS Day-Night Band Calibration

    Directory of Open Access Journals (Sweden)

    Xuexia Chen

    2016-11-01

    Full Text Available In this study, the observations from S-NPP VIIRS Day-Night band (DNB and Moderate resolution bands (M bands of Libya 4 and Dome C over the first four years of the mission are used to assess the DNB low gain calibration stability. The Sensor Data Records produced by NASA Land Product Evaluation and Algorithm Testing Element (PEATE are acquired from nearly nadir overpasses for Libya 4 desert and Dome C snow surfaces. A kernel-driven bidirectional reflectance distribution function (BRDF correction model is used for both Libya 4 and Dome C sites to correct the surface BRDF influence. At both sites, the simulated top-of-atmosphere (TOA DNB reflectances based on SCIAMACHY spectral data are compared with Land PEATE TOA reflectances based on modulated Relative Spectral Response (RSR. In the Libya 4 site, the results indicate a decrease of 1.03% in Land PEATE TOA reflectance and a decrease of 1.01% in SCIAMACHY derived TOA reflectance over the period from April 2012 to January 2016. In the Dome C site, the decreases are 0.29% and 0.14%, respectively. The consistency between SCIAMACHY and Land PEATE data trends is good. The small difference between SCIAMACHY and Land PEATE derived TOA reflectances could be caused by changes in the surface targets, atmosphere status, and on-orbit calibration. The reflectances and radiances of Land PEATE DNB are also compared with matching M bands and the integral M bands based on M4, M5, and M7. The fitting trends of the DNB to integral M bands ratios indicate a 0.75% decrease at the Libya 4 site and a 1.89% decrease at the Dome C site. Part of the difference is due to an insufficient number of sampled bands available within the DNB wavelength range. The above results indicate that the Land PEATE VIIRS DNB product is accurate and stable. The methods used in this study can be used on other satellite instruments to provide quantitative assessments for calibration stability.

  3. DATA ACQUISITION AND APPLICATIONS OF SIDE-LOOKING AIRBORNE RADAR IN THE U. S. GEOLOGICAL SURVEY.

    Science.gov (United States)

    Jones, John Edwin; Kover, Allan N.

    1985-01-01

    The Side-Looking Airborne Radar (SLAR) program encompasses a multi-discipline effort involving geologists, hydrologists, engineers, geographers, and cartographers of the U. S. Geological Survey (USGS). Since the program began in 1980, more than 520,000 square miles of aerial coverage of SLAR data in the conterminous United States and Alaska have been acquired or contracted for acquisition. The Geological Survey has supported more than 60 research and applications projects addressing the use of this technology in the earth sciences since 1980. These projects have included preparation of lithographic reproductions of SLAR mosaics, research to improve the cartographic uses of SLAR, research for use of SLAR in assessing earth hazards, and studies using SLAR for energy and mineral exploration through improved geologic mapping.

  4. Probabilistic discrimination between liquid rainfall events, hailstorms, biomass burning and industrial fires from C-Band Radar Polarimetric Variables

    Science.gov (United States)

    Valencia, J. M.; Sepúlveda, J.; Hoyos, C.; Herrera, L.

    2017-12-01

    Characterization and identification of fire and hailstorm events using weather radar data in a tropical complex topography region is an important task in risk management and agriculture. Polarimetric variables from a C-Band Dual polarization weather radar have potential uses in particle classification, due to the relationship their sensitivity to shape, spatial orientation, size and fall behavior of particles. In this sense, three forest fires and two chemical fires were identified for the Áburra Valley regions. Measurements were compared between each fire event type and with typical data radar retrievals for liquid precipitation events. Results of this analysis show different probability density functions for each type of event according to the particles present in them. This is very important and useful result for early warning systems to avoid precipitation false alarms during fire events within the study region, as well as for the early detection of fires using radar retrievals in remote cases. The comparative methodology is extended to hailstorm cases. Complementary sensors like laser precipitation sensors (LPM) disdrometers and meteorological stations were used to select dates of solid precipitation occurrence. Then, in this dates weather radar data variables were taken in pixels surrounding the stations and solid precipitation polar values were statistically compared with liquid precipitation values. Spectrum precipitation measured by LPM disdrometer helps to define typical features like particles number, fall velocities and diameters for both precipitation types. In addition, to achieve a complete hailstorm characterization, other meteorological variables were analyzed: wind field from meteorological stations and radar wind profiler, profiling data from Micro Rain Radar (MRR), and thermodynamic data from a microwave radiometer.

  5. Photoresponse Enhancement in Monolayer ReS2 Phototransistor Decorated with CdSe-CdS-ZnS Quantum Dots.

    Science.gov (United States)

    Qin, Jing-Kai; Ren, Dan-Dan; Shao, Wen-Zhu; Li, Yang; Miao, Peng; Sun, Zhao-Yuan; Hu, PingAn; Zhen, Liang; Xu, Cheng-Yan

    2017-11-15

    ReS 2 films are considered as a promising candidate for optoelectronic applications due to their direct band gap character and optical/electrical anisotropy. However, the direct band gap in a narrow spectrum and the low absorption of atomically thin flakes weaken the prospect for light-harvesting applications. Here, we developed an efficient approach to enhance the performance of a ReS 2 -based phototransistor by coupling CdSe-CdS-ZnS core-shell quantum dots. Under 589 nm laser irradiation, the responsivity of the ReS 2 phototransistor decorated with quantum dots could be enhanced by more than 25 times (up to ∼654 A/W) and the rising and recovery time can be also reduced to 3.2 and 2.8 s, respectively. The excellent optoelectronic performance is originated from the coupling effect of quantum dots light absorber and cross-linker ligands 1,2-ethanedithiol. Photoexcited electron-hole pairs in quantum dots can separate and transfer efficiently due to the type-II band alignment and charge exchange process at the interface. Our work shows that the simple hybrid zero- and two-dimensional hybrid system can be employed for photodetection applications.

  6. Electrodynamic characterisitcs measurements of higher order modes in S-band cavity

    Science.gov (United States)

    Donetsky, R.; Lalayan, M.; Sobenin, N. P.; Orlov, A.; Bulygin, A.

    2017-12-01

    The 800 MHz superconducting cavities with grooved beam pipes were suggested as one of the harmonic cavities design options for High Luminosity LHC project. Cavity simulations were carried out and scaled aluminium prototype having operational mode frequency of 2400 MHz was manufactured for testing the results of simulations. The experimental measurements of transverse shunt impedance with error estimation for higher order modes TM 110 and TE 111 for S-band elliptical cavity were done. The experiments using dielectric and metallic spherical beads and with ring probe were carried out. The Q-factor measurements for two-cell structure and array of two cells were carried out.

  7. Multibunch emittance growth and its corrections in S-Band linear collider

    International Nuclear Information System (INIS)

    Gao, J.

    1994-11-01

    Multibunch emittance growths caused by long range wake fields with the misalignments of accelerating structures and quadrupoles in S-Band linear collider are studied. Tolerances for the misalignment errors of accelerating structures and quadrupoles are given corresponding to different detuned+damped structures. At the end of main linac, emittance corrector (EC) is proposed to be used to reduce further the multibunch emittance. Numerical simulations show that the effect of EC is obvious (multibunch emittance can be reduced about one order of magnitude), and it is believed that this kind of EC will be necessary for future linear colliders. (author). 16 refs., 21 figs., 4 tabs

  8. Multi-variable X-band radar observation and tracking of ash plume from Mt. Etna volcano on November 23, 2013 event

    Science.gov (United States)

    Montopoli, Mario; Vulpiani, Gianfranco; Riccci, Matteo; Corradini, Stefano; Merucci, Luca; Marzano, Frank S.

    2015-04-01

    Ground based weather radar observations of volcanic ash clouds are gaining momentum after recent works which demonstrated their potential use either as stand alone tool or in combination with satellite retrievals. From an operational standpoint, radar data have been mainly exploited to derive the height of ash plume and its temporal-spatial development, taking into account the radar limitation of detecting coarse ash particles (from approximately 20 microns to 10 millimeters and above in terms of particle's radius). More sophisticated radar retrievals can include airborne ash concentration, ash fall rate and out-flux rate. Marzano et al. developed several volcanic ash radar retrieval (VARR) schemes, even though their practical use is still subject to a robust validation activity. The latter is made particularly difficult due to the lack of field campaigns with multiple observations and the scarce repetition of volcanic events. The radar variable, often used to infer the physical features of actual ash clouds, is the radar reflectivity named ZHH. It is related to ash particle size distribution and it shows a nice power law relationship with ash concentration. This makes ZHH largely used in radar-volcanology studies. However, weather radars are often able to detect Doppler frequency shifts and, more and more, they have a polarization-diversity capability. The former means that wind speed spectrum of the ash cloud is potentially inferable, whereas the latter implies that variables other than ZHH are available. Theoretically, these additional radar variables are linked to the degree of eccentricity of ash particles, their orientation and density as well as the presence of strong turbulence effects. Thus, the opportunity to refine the ash radar estimates so far developed can benefit from the thorough analysis of radar Doppler and polarization diversity. In this work we show a detailed analysis of Doppler shifts and polarization variables measured by the X band radar

  9. Band Alignments, Valence Bands, and Core Levels in the Tin Sulfides SnS, SnS2, and Sn2S3: Experiment and Theory

    OpenAIRE

    Whittles, TJ; Burton, LA; Skelton, JM; Walsh, A; Veal, TD; Dhanak, VR

    2016-01-01

    Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including...

  10. La Gigantomaquia, símbolo socio-político en la concepción de la polis griega

    OpenAIRE

    Cristina Delgado Linacero

    1999-01-01

    Este estudio propone una interpretación del mito de la Gigantomaquia como símbolo político y sociológico de la evolución de la ciudad griega. Está basado en fuentes literarias y visuales que aparecieron entre los siglos viii y ii a.C. El desafío final a la autoridad de los Olímpicos viene de los Gigantes, hijos de Gala, nacidos de las gotas de sangre brotada de los miembros emasculados de Urano. Fue el tema del friso norte del Tesoro de los Sifnios en Deifi y tuvo una importancia particular e...

  11. Predikce rizika vzniku přívalové povodně s využitím dat meteorologických radarů

    Czech Academy of Sciences Publication Activity Database

    Rapant, P.; Kolejka, Jaromír; Inspektor, T.

    2016-01-01

    Roč. 50, č. 3 (2016), s. 162-166 ISSN 0044-4863 R&D Projects: GA MV VG20132015106 Institutional support: RVO:68145535 Keywords : flash floods * prediction * weather radar * early warning Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://147.213.211.222/sites/ default /files/2016_3_162_166_Rapant_a_kol.pdf

  12. Sõjatandri puudumine ajab Eesti sõdurid Riia alla / Peeter Kuimet

    Index Scriptorium Estoniae

    Kuimet, Peeter

    2006-01-01

    Õppusteks vajaliku suure polügooni puudumise tõttu pidi elukutselistest sõduritest koosnev Scoutspataljon korraldama õppuse Gungnir 2006 Lätis asuval Adazhi polügoonil, kus on võimalik kasutada ka reaalset lahingumoona. Kaart: Adazhi polügoon. Lisa: Scoutspataljon

  13. Production and testing of an s-band resonator with a Nb3Sn surface

    International Nuclear Information System (INIS)

    Peiniger, M.

    1983-01-01

    This report describes the preparation of a niobium s-band resonator with Nb3Sn surface using a special vapor phase deposition method. High-frequency superconductivity tests were performed on this resonator. Measurements of transition temperature, penetration depth, energy gap, and temperature dependence of surface conductivity of Nb3Sn, and resonator behaviour at high electrical field strengths are reported. (GSCH)

  14. Hurricane Rita Track Radar Image with Topographic Overlay

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Animation About the animation: This simulated view of the potential effects of storm surge flooding on Galveston and portions of south Houston was generated with data from the Shuttle Radar Topography Mission. Although it is protected by a 17-foot sea wall against storm surges, flooding due to storm surges caused by major hurricanes remains a concern. The animation shows regions that, if unprotected, would be inundated with water. The animation depicts flooding in one-meter increments. About the image: The Gulf Coast from the Mississippi Delta through the Texas coast is shown in this satellite image from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) overlain with data from the Shuttle Radar Topography Mission (SRTM), and the predicted storm track for Hurricane Rita. The prediction from the National Weather Service was published Sept. 22 at 4 p.m. Central Time, and shows the expected track center in black with the lighter shaded area indicating the range of potential tracks the storm could take. Low-lying terrain along the coast has been highlighted using the SRTM elevation data, with areas within 15 feet of sea level shown in red, and within 30 feet in yellow. These areas are more at risk for flooding and the destructive effects of storm surge and high waves. Data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Geospatial

  15. Measurement of Precipitation in the Alps Using Dual-Polarization C-Band Ground-Based Radars, the GPM Spaceborne Ku-Band Radar, and Rain Gauges

    Directory of Open Access Journals (Sweden)

    Marco Gabella

    2017-11-01

    Full Text Available The complex problem of quantitative precipitation estimation in the Alpine region is tackled from four different points of view: (1 the modern MeteoSwiss network of automatic telemetered rain gauges (GAUGE; (2 the recently upgraded MeteoSwiss dual-polarization Doppler, ground-based weather radar network (RADAR; (3 a real-time merging of GAUGE and RADAR, implemented at MeteoSwiss, in which a technique based on co-kriging with external drift (CombiPrecip is used; (4 spaceborne observations, acquired by the dual-wavelength precipitation radar on board the Global Precipitation Measuring (GPM core satellite. There are obviously large differences in these sampling modes, which we have tried to minimize by integrating synchronous observations taken during the first 2 years of the GPM mission. The data comprises 327 “wet” overpasses of Switzerland, taken after the launch of GPM in February 2014. By comparing the GPM radar estimates with the MeteoSwiss products, a similar performance was found in terms of bias. On average (whole country, all days and seasons, both solid and liquid phases, underestimation is as large as −3.0 (−3.4 dB with respect to RADAR (GAUGE. GPM is not suitable for assessing what product is the best in terms of average precipitation over the Alps. GPM can nevertheless be used to evaluate the dispersion of the error around the mean, which is a measure of the geographical distribution of the error inside the country. Using 221 rain-gauge sites, the result is clear both in terms of correlation and in terms of scatter (a robust, weighted measure of the dispersion of the multiplicative error around the mean. The best agreement was observed between GPM and CombiPrecip, and, next, between GPM and RADAR, whereas a larger disagreement was found between GPM and GAUGE. Hence, GPM confirms that, for precipitation mapping in the Alpine region, the best results are obtained by combining ground-based radar with rain-gauge measurements using

  16. A high peak power S-band switching system for the Advanced Photon Source (APS) Linear Accelerator (Linac)

    International Nuclear Information System (INIS)

    Grelick, A. E.

    1998-01-01

    An S-band linear accelerator is the source of particles and front end of the Advanced Photon Source [1] injector. Additionally, it will be used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). To provide maximum linac availability for all uses, an additional modulator-klystron subsystem has been built,and a waveguide-switching and distribution subsystem is now under construction. The combined subsystems provide a hot spare for any of the five S-band transmitters that power the lina cand have been given the additional function of powering an rf gun test stand whenever they are not otherwise needed. Design considerations for the waveguide-switching subsystem, topology selection, timing, control, and system protection provisions are described

  17. "As vezes, somos todos palestinos": O uso político da Questão Palestina por líderes árabes na segunda metade do século XX

    Directory of Open Access Journals (Sweden)

    Murilo Sebe Bon MEIHY

    2014-12-01

    Full Text Available O presente artigo discute o processo de transformação da chamada "Questão Palestina" em elemento de destaque do discurso político de líderes árabes em três países: Egito, Líbia e Líbano, a partir da segunda metade do século XX, e ressalta como a busca por liderança regional e visibilidade internacional durante o período da Guerra Fria convertia o tema dos conflitos entre Israel e Palestina em princípio norteador da agenda política retórica dos países árabes. A partir desses três cenários específicos, no artigo pretende-se analisar a permanência do conflito entre palestinos e israelenses como o principal fator de instabilidade no Oriente Médio, considerando-se o uso político que cada país atribuía a este problema geopolítico.

  18. La nueva política en el Chile postdictatorial: ¿Pasividad ciudadana o clientelismo desde abajo? (1990-1996 = A nova política no Chile pós-ditatorial: passividade cidadã ou clientelismo popular? (1990-1996 = The new politics in the post-dictatorship Chile: passivity Citizen or clientelism from below? (1990-1996

    Directory of Open Access Journals (Sweden)

    Alvarez Vallejos, Rolando

    2014-01-01

    Full Text Available Os governos posteriores a ditadura militar de Pinochet, no Chile, foram avaliados política e institucionalmente como produtos da “engenharia política” de líderes das coalizões de centro-esquerda, da direita política e dos chamados “poderes factuais”. O presente artigo indaga sobre o papel que a cidadania chilena exerceu na configuração dessa política pós-ditatorial. Consideramos que as demandas e preocupações dos cidadãos, longe de permanecerem inativas ou como meras observadoras dos acontecimentos vividos no país, foram fundamentais para a reconfiguração da política chilena. Esta importância se expressou em órgãos de poder local, como os municípios, que se converteram na instância de poder mais próxima da população. Entendemos que a “nova política chilena”, vista aqui como despolitizada e pragmática, surgiu e foi fomentada a partir dos municípios

  19. Ku-Band radar penetration into Snow over Arctic Sea Ice

    DEFF Research Database (Denmark)

    Hendricks, Stefan; Stenseng, Lars; Helm, Veit

    is the snow/air interface, whereas radar waves interact with the variable physical properties of the snow cover on the Arctic sea ice. In addition, radar elevation measurements may vary for different retracker algorithms, which determine the track point of the scattered echo power distribution. Since accurate...... knowledge of the reflection horizon is critical for sea ice thickness retrieval, validation data is necessary to investigate the penetration of radar waves into the snow for the upcoming CryoSat-2 mission. Furthermore, the combination of both optical and RF wavelengths might be used to derive snow thickness......, if radar altimeters are capable of measuring the distance to the snow-ice interface reliably. We present the results of aircraft campaigns in the Arctic with a scanning laser altimeter and the Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) of the European Space Agency. The elevation...

  20. Os militantes são mais informados? Desigualdade e informação política nas eleições de 2002

    Directory of Open Access Journals (Sweden)

    Lucio Rennó

    2006-11-01

    Full Text Available As organizações da sociedade civil têm um papel didático na instrução de seus membros sobre política que extrapola as questões imediatas de interesse dessas organizações? A maior parte da literatura, especialmente aquela sobre o orçamento participativo (OP do Partido dos Trabalhadores do Brasil, sustenta que o OP é uma estrutura de oportunidade para que os indivíduos se reúnam e debatam não só problemas locais, mas também discutam política num sentido mais amplo. A mesma lógica se aplica a outras formas de militância, tais como participação em sindicatos, partidos políticos, associações de bairro e grupos de igreja. Este trabalho procura testar, usando dados longitudinais de opinião pública de eleitores brasileiros coletados nas eleições de 2002, se os militantes da sociedade civil organizada são, de fato, mais bem informados sobre política, especificamente, sobre questões eleitorais. Além disso, este trabalho testa também se potenciais diferenças de informação causadas por gênero, raça e classe são atenuadas pela participação em organizações da sociedade civil.Do civil society organizations have a didactic role in instructing its members about politics that extrapolates the immediate issues of interest of that organization? Most of the literature, especially that on the role of the participatory budgeting process of the Workers´ Party in Brazil, claims that such meetings are an opportunity structure for individuals to come together and not only debate their local problems, but also discuss politics more broadly. The same logic applies to other forms of activism, such as participation in Labor Unions, political parties, neighborhood associations and even church groups. This paper attempts to test, using a unique public opinion panel dataset of Brazilian voters collected in the 2002 elections, if activists are, in fact, better informed about politics, specifically, about campaign issues. In addition

  1. Meteorological radar services: a brief discussion and a solution in practice

    Science.gov (United States)

    Nicolaides, K. A.

    2014-08-01

    The Department of Meteorology is the organization designated by the Civil Aviation Department and by the National Supervisory Authority of the Republic of Cyprus, as an air navigation service provider, based on the regulations of the Single European Sky. Department of Meteorology holds and maintains also an ISO: 9001/2008, Quality System, for the provision of meteorological and climatological services to aeronautic and maritime community, but also to the general public. In order to fulfill its obligations the Department of Meteorology customs the rather dense meteorological stations network, with long historical data series, installed and maintained by the Department, in parallel with modelling and Numerical Weather Prediction (NWP), along with training and gaining of expertise. Among the available instruments in the community of meteorologists is the meteorological radar, a basic tool for the needs of very short/short range forecasting (nowcasting). The Department of Meteorology installed in the mid 90's a C-band radar over «Throni» location and expanded its horizons in nowcasting, aviation safety and warnings issuance. The radar has undergone several upgrades but today technology has over passed its rather old technology. At the present the Department of Meteorology is in the process of buying Meteorological Radar Services as a result of a public procurement procedure. Two networked X-band meteorological radar will be installed (the project now is in the phase of infrastructure establishment while the hardware is in the process of assemble), and maintained from Space Hellas (the contractor) for a 13 years' time period. The present article must be faced as a review article of the efforts of the Department of Meteorology to support its weather forecasters with data from meteorological radar.

  2. Monogràfic "VII Congrés Internacional Internet, Dret i Política: Neutralitat de la Xarxa i altres reptes per al futur d’Internet"

    Directory of Open Access Journals (Sweden)

    Miquel Peguera (coord.

    2012-03-01

    Full Text Available

    Presentació introductòria del monogràfic dedicat al VII Congrés Internacional Internet, Dret i Política (IDP 2011: Neutralitat de la Xarxa i altres reptes per al futur d'Internet.

  3. Espacios de socialización política y representaciones de la política en la Universidad de Antioquia

    Directory of Open Access Journals (Sweden)

    Deicy Patricia Hurtado Galeano

    2017-01-01

    Full Text Available Este artículo describe los procesos de socialización política de los universitarios a través de las interacciones cara a cara —en la familia, en el vecindario, en la universidad— y de los medios de comunicación análogos —televisión, radio, prensa— y virtuales —redes sociales, blogs—. Una vez analizado cómo se informan sobre política y en qué espacios hablan de estos temas, se analiza el interés en la política, así como las imágenes que los universitarios tienen de esta. Con base en estas variables se concluye que la Universidad es un entorno político en el que no puede verificase una apatía política en los actores clave de la vida universitaria —estudiantes, profesores y empleados administrativos—, no solo porque sí les interesan estos asuntos, sino porque se informan y conversan sobre política en distintos espacios de socialización, se sienten con capacidades y competencias para enfrentar esa esfera, y predomina una visión crítica de la política y de la forma como es conducida en la sociedad colombiana.

  4. TlHgInS 3 : An Indirect-Band-Gap Semiconductor with X-ray Photoconductivity Response

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hao; Malliakas, Christos D.; Han, Fei; Chung, Duck Young; Kanatzidis, Mercouri G.

    2015-08-11

    The quaternary compound TlHgInS3 crystallizes in a new structure type of space group, C2/c, with cell parameters a = 13.916(3) angstrom, b = 3.9132(8) angstrom, c = 21.403(4) angstrom, beta = 104.16(3)degrees, V = 1130.1(8) angstrom(3), and rho = 7.241 g/cm(3). The structure is a unique three-dimensional framework with parallel tunnels, which is formed by (1)(infinity)[InS33-] infinite chains bridged by linearly coordinated Hg2+ ions. TlHgInS3 is a semiconductor with a band gap of 1.74 eV and a resistivity of similar to 4.32 G Omega cm. TlHgInS3 single crystals exhibit photocurrent response when exposed to Ag X-rays. The mobility-lifetime product (mu tau) of the electrons and holes estimated from the photocurrent measurements are (mu tau)(e) approximate to 3.6 x 10(-4) cm(2)/V and (mu tau)(h) approximate to 2.0 x 10(-4) cm(2)/V. Electronic structure calculations at the density functional theory level indicate an indirect band gap and a relatively small effective mass for both electrons and holes. Based on the photoconductivity data, TlHgInS3 is a potential material for radiation detection applications.

  5. Observation of snowfall with a low-power FM-CW K-band radar (Micro Rain Radar)

    Science.gov (United States)

    Kneifel, Stefan; Maahn, Maximilian; Peters, Gerhard; Simmer, Clemens

    2011-06-01

    Quantifying snowfall intensity especially under arctic conditions is a challenge because wind and snow drift deteriorate estimates obtained from both ground-based gauges and disdrometers. Ground-based remote sensing with active instruments might be a solution because they can measure well above drifting snow and do not suffer from flow distortions by the instrument. Clear disadvantages are, however, the dependency of e.g. radar returns on snow habit which might lead to similar large uncertainties. Moreover, high sensitivity radars are still far too costly to operate in a network and under harsh conditions. In this paper we compare returns from a low-cost, low-power vertically pointing FM-CW radar (Micro Rain Radar, MRR) operating at 24.1 GHz with returns from a 35.5 GHz cloud radar (MIRA36) for dry snowfall during a 6-month observation period at an Alpine station (Environmental Research Station Schneefernerhaus, UFS) at 2,650 m height above sea level. The goal was to quantify the potential and limitations of the MRR in relation to what is achievable by a cloud radar. The operational MRR procedures to derive standard radar variables like effective reflectivity factor ( Z e) or the mean Doppler velocity ( W) had to be modified for snowfall since the MRR was originally designed for rain observations. Since the radar returns from snowfall are weaker than from comparable rainfall, the behavior of the MRR close to its detection threshold has been analyzed and a method is proposed to quantify the noise level of the MRR based on clear sky observations. By converting the resulting MRR- Z e into 35.5 GHz equivalent Z e values, a remaining difference below 1 dBz with slightly higher values close to the noise threshold could be obtained. Due to the much higher sensitivity of MIRA36, the transition of the MRR from the true signal to noise can be observed, which agrees well with the independent clear sky noise estimate. The mean Doppler velocity differences between both radars

  6. ¡Pelayo vive! : un arquetipo político en el horizonte ideológico del reino asturleonés

    Directory of Open Access Journals (Sweden)

    Arsenio Dacosta

    1997-01-01

    Full Text Available Pelayo vive. Los diversos trabajos aparecidos en los últimos años son muestra de la vitalidad del primer rey cristiano de la Edad Media hispana. Tales análisis han tratado de probar la validez de dos teorías historiográficas contrapuestas sobre los orígenes políticos y sociales del reino asturleonés. El presente artículo, en espera de la apertura de un debate al respecto, plantea otra posibilidad explicativa del contenido del ciclo cronístico asturiano del siglo ix, fuentes principales para el estudio de esta figura. En este sentido, aquí se procede al análisis de las mismas retomando estudios parciales, hoy prácticamente olvidados, que demuestran que gran parte de su contenido es básicamente literario. Pero se trata de un tipo de literatura muy especial, formada con retales de hagiografías altomedievales, pasajes bíblicos y leyendas de muy diverso origen. En este sentido, el autor plantea el hecho de que un Pelayo distinto viva tras el contenido aparentemente histórico de las crónicas asturianas. Este personaje legendario y su particular epopeya se inscribiría dentro de una política desarrollada a fines del siglo ix en la corte de Alfonso III conocida bajo el nombre de neogoticismo. Así, el relato legendario de Pelayo constituye un producto neogoticista tendente a crear un mito fundacional, un ascendiente legendario para el monarca y un arquetipo político útil en los procesos de integración social y política en el reino asturleonés.Pelayo lives. The different papers published in these years show the vitality of the first christian king of the spanish Middie Age. These analysis have tried to prove the validity of two opposite historigraphyc theories about the social and political origins of the asturleones kingdom. This article, while waiting the begining of a debate about this subject, introduces another alternative to explain the content of the asturian chronicle cycle of the IX century, which represente the main

  7. Optical and electronic properties of 2 H -Mo S2 under pressure: Revealing the spin-polarized nature of bulk electronic bands

    Science.gov (United States)

    Brotons-Gisbert, Mauro; Segura, Alfredo; Robles, Roberto; Canadell, Enric; Ordejón, Pablo; Sánchez-Royo, Juan F.

    2018-05-01

    Monolayers of transition-metal dichalcogenide semiconductors present spin-valley locked electronic bands, a property with applications in valleytronics and spintronics that is usually believed to be absent in their centrosymmetric (as the bilayer or bulk) counterparts. Here we show that bulk 2 H -Mo S2 hides a spin-polarized nature of states determining its direct band gap, with the spin sequence of valence and conduction bands expected for its single layer. This relevant finding is attained by investigating the behavior of the binding energy of A and B excitons under high pressure, by means of absorption measurements and density-functional-theory calculations. These results raise an unusual situation in which bright and dark exciton degeneracy is naturally broken in a centrosymmetric material. Additionally, the phonon-assisted scattering process of excitons has been studied by analyzing the pressure dependence of the linewidth of discrete excitons observed at the absorption coefficient edge of 2 H -Mo S2 . Also, the pressure dependence of the indirect optical transitions of bulk 2 H -Mo S2 has been analyzed by absorption measurements and density-functional-theory calculations. These results reflect a progressive closure of the indirect band gap as pressure increases, indicating that metallization of bulk Mo S2 may occur at pressures higher than 26 GPa.

  8. Synthesis and optical properties of CdS/ZnS coreshell nanoparticles

    International Nuclear Information System (INIS)

    Saraswathi Amma, B.; Manzoor, K.; Ramakrishna, K.; Pattabi, Manjunatha

    2008-01-01

    Synthesis and optical properties of manganese (Mn 2+ )-doped, polyvinyl pyrrolidone (PVP)-capped cadmium sulphide (CdS) nanoparticles coated with zinc sulphide (ZnS) are reported. Colloidal solution of Mn 2+ -doped CdS nanoparticles capped with PVP is synthesized using methanol as solvent. PVP is used to control the particle size and to prevent agglomeration. Mn 2+ doping is expected to help in increasing the CdS band edge photoluminescence (PL) emission. Addition of zinc nitrate and sodium sulphide alternately to the Mn 2+ -doped, PVP-stabilized CdS colloid led to the formation of ZnS-coated CdS coreshell nanoparticles. Photoluminescence emission spectra recorded for (CdS-PVP)Mn nanoparticles showed two emission peaks, one at 416 nm and the other weaker peak at 586 nm which is attributed to Mn 2+ emission. Intensity of Mn 2+ peak increased with increase in the Mn 2+ content. Mn 2+ emission disappears when ZnS is coated over the CdS core, resulting in pure CdS band edge emission

  9. TDRSS S-shuttle unique receiver equipment

    Science.gov (United States)

    Weinberg, A.; Schwartz, J. J.; Spearing, R.

    1985-01-01

    Beginning with STS-9, the Tracking and Date Relay Satellite system (TDRSS) will start providing S- and Ku-band communications and tracking support to the Space Shuttle and its payloads. The most significant element of this support takes place at the TDRSS White Sands Ground Terminal, which processes the Shuttle return link S- and Ku-band signals. While Ku-band hardware available to other TDRSS users is also applied to Ku-Shuttle, stringent S-Shuttle link margins have precluded the application of the standard TDRSS S-band processing equipment to S-Shuttle. It was therfore found necessary to develop a unique S-Shuttle Receiver that embodies state-of-the-art digital technology and processing techniques. This receiver, developed by Motorola, Inc., enhances link margins by 1.5 dB relative to the standard S-band equipment and its bit error rate performance is within a few tenths of a dB of theory. An overview description of the Space Shuttle Receiver Equipment (SSRE) is presented which includes the presentation of block diagrams and salient design features. Selected, measured performance results are also presented.

  10. S-band multiple-access interference study for advanced tracking and data relay satellite systems

    Science.gov (United States)

    Peng, Wei-Chung; Yang, Chau-Chin

    1990-01-01

    The results of a study on the effect of mutual interference among S-band multiple access (SMA) system users of advanced tracking and data relay satellite system (ATDRSS) are presented. In the ATDRSS era, the SMA system is required to support data rates ranging from 10 kb/s to 3 Mb/s. The system will consist of four advanced tracking and data relay satellites (ATDRS) each supporting up to five telemetry links. All users have 10 MHz bandwidth with their carrier frequency equal to 2.2875 GHz. A hybrid SDMA/CDMA scheme is used to mitigate the effect of the interference among system users. SMA system interference probability is evaluated with CLASS software. User link margin degradation due to mutual interference between two users is evaluated. System interference probability is evaluated for the projected 1996 mission model, a reference mission model, and a modified reference mission model.

  11. Space Radar Image of Flevoland, Netherlands

    Science.gov (United States)

    1999-01-01

    This is a three-frequency false color image of Flevoland, The Netherlands, centered at 52.4 degrees north latitude, 5.4 degrees east longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard space shuttle Endeavour on April 14, 1994. It was produced by combining data from the X-band, C-band and L-band radars. The area shown is approximately 25 kilometers by 28 kilometers (15-1/2 by 17-1/2 miles). Flevoland, which fills the lower two-thirds of the image, is a very flat area that is made up of reclaimed land that is used for agriculture and forestry. At the top of the image, across the canal from Flevoland, is an older forest shown in red; the city of Harderwijk is shown in white on the shore of the canal. At this time of the year, the agricultural fields are bare soil, and they show up in this image in blue. The changes in the brightness of the blue areas are equal to the changes in roughness. The dark blue areas are water and the small dots in the canal are boats. This SIR-C/X-SAR supersite is being used for both calibration and agricultural studies. Several soil and crop ground-truth studies will be conducted during the shuttle flight. In addition, about 10calibration devices and 10 corner reflectors have been deployed to calibrate and monitor the radar signal. One of these transponders can be seen as a bright star in the lower right quadrant of the image. This false-color image was made using L-band total power in the red channel, C-band total power in the green channel, and X-band VV polarization in the blue channel. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by

  12. A 100 GHz Polarimetric Compact Radar Range for Scale-Model Radar Cross Section Measurements

    Science.gov (United States)

    2013-10-01

    common radar bands. ACKNOWLEDGEMENTS The authors wish to thank David Jillson (UML STL – Electrical Engineer) for efforts involved in RF and DC wiring...Waldman J., Fetterman H.R., Duffy P.E., Bryant T.G., Tannenwald P.E., “Submillimeter Model Measurements and Their Applications to Millimeter Radar

  13. Observations of the Galaxy NGC 3077 in the Narrow-Band [S II] and Hα Filters

    Directory of Open Access Journals (Sweden)

    Andjelić M.

    2011-09-01

    Full Text Available We present observations of the H I tidal arm near a dwarf galaxy NGC 3077 (member of the M81 galaxy group in the narrow-band [S II] and Hα filters. Observations were carried out in 2011 March with the 2 m RCC telescope at the NAO Rozhen, Bulgaria. Our search for possible supernova remnant candidates (identified as sources with enhanced [S II] emission relative to their Hα emission in this region yielded no sources of this kind. Nevertheless, we found a number of objects with significant Hα emission that probably represent uncatalogued, low brightness H II regions.

  14. Median and ulnar neuropathies in U.S. Army Medical Command Band members.

    Science.gov (United States)

    Shaffer, Scott W; Koreerat, Nicholas R; Gordon, Lindsay B; Santillo, Douglas R; Moore, Josef H; Greathouse, David G

    2013-12-01

    Musicians have been reported as having a high prevalence of upper-extremity musculoskeletal disorders, including carpal tunnel syndrome. The purpose of this study was to determine the presence of median and ulnar neuropathies in U.S. Army Medical Command (MEDCOM) Band members at Fort Sam Houston, Texas. Thirty-five MEDCOM Band members (30 males, 5 females) volunteered to participate. There were 33 right-handed musicians, and the mean length of time in the MEDCOM Band was 12.2 yrs (range, 1-30 yrs). Subjects completed a history form, were interviewed, and underwent a physical examination of the cervical spine and bilateral upper extremities. Nerve conduction studies of the bilateral median and ulnar nerves were performed. Electrophysiological variables served as the reference standard for median and ulnar neuropathy and included distal sensory latencies, distal motor latencies, amplitudes, conduction velocities, and comparison study latencies. Ten of the 35 subjects (29%) presented with abnormal electrophysiologic values suggestive of an upper extremity mononeuropathy. Nine of the subjects had abnormal median nerve electrophysiologic values at or distal to the wrist; 2 had bilateral abnormal values. One had an abnormal ulnar nerve electrophysiologic assessment at the elbow. Nine of these 10 subjects had clinical examination findings consistent with the electrophysiological findings. The prevalence of mononeuropathies in this sample of band members is similar to that found in previous research involving civilian musicians (20-36%) and far exceeds that reported in the general population. Prospective research investigating screening, examination items, and injury prevention measures in musicians appears to be warranted.

  15. TCSP ER-2 DOPPLER RADAR (EDOP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The TCSP ER-2 DOPPLER RADAR (EDOP) dataset was collected by the ER-2 Doppler radar (EDOP), which is an X-band (9.6 GHz) Doppler radar mounted in the nose of the ER-2...

  16. CAMEX-4 ER-2 DOPPLER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-4 ER-2 Doppler Radar dataset was collected by the ER-2 Doppler radar (EDOP), which is an X-band (9.6 GHz) Doppler radar mounted in the nose of ER-2. The...

  17. A elaboração das políticas públicas de turismo do Estado do Amapá com base nos instrumentos políticos propostos por Bramwell

    Directory of Open Access Journals (Sweden)

    Cálidon Costa Conceição

    2015-12-01

    Full Text Available O presente estudo tem como escopo caracterizar as políticas públicas de turismo do Estado do Amapá no período de 2003 a 2013 através dos instrumentos políticos proposto por Bramwell, que são o encorajamento, incentivos financeiros, investimentos públicos, e regulamentação, sendo acrescido mais um instrumento nesta pesquisa denominado de comprometimento dos atores do turismo. Os instrumentos políticos são utilizados para entender como surgiram as políticas públicas de turismo do Estado do Amapá, sendo elencados quatro programas e um projeto entre os anos de 2003 a 2013 que serviram como base para caracterizar essa política. A metodologia utilizada foi através de pesquisa bibliográfica e documental, com abordagem qualitativa, tendo suporte nos instrumentos políticos que possibilitaram entender a elaboração desta política de turismo, que teve como base os Planos Nacionais de Turismo e o Programa de Regionalização do Turismo.

  18. The U.S. Geological Survey Bird Banding Laboratory: an integrated scientific program supporting research and conservation of North American birds

    Science.gov (United States)

    Smith, Gregory J.

    2013-01-01

    The U.S. Geological Survey (USGS) Bird Banding Laboratory (BBL) was established in 1920 after ratification of the Migratory Bird Treaty Act with the United Kingdom in 1918. During World War II, the BBL was moved from Washington, D.C., to what is now the USGS Patuxent Wildlife Research Center (PWRC). The BBL issues permits and bands to permittees to band birds, records bird band recoveries or encounters primarily through telephone and Internet reporting, and manages more than 72 million banding records and more than 4.5 million records of encounters using state-of-the-art technologies. Moreover, the BBL also issues bands and manages banding and encounter data for the Canadian Bird Banding Office (BBO). Each year approximately 1 million bands are shipped from the BBL to banders in the United States and Canada, and nearly 100,000 encounter reports are entered into the BBL systems. Banding data are essential for regulatory programs, especially migratory waterfowl harvest regulations. The USGS BBL works closely with the U.S. Fish and Wildlife Service (USFWS) to develop regulations for the capture, handling, banding, and marking of birds. These regulations are published in the Code of Federal Regulations (CFR). In 2006, the BBL and the USFWS Division of Migratory Bird Management (DMBM) began a comprehensive revision of the banding regulations. The bird banding community has three major constituencies: Federal and State agency personnel involved in the management and conservation of bird populations that include the Flyway Councils, ornithological research scientists, and avocational banders. With increased demand for banding activities and relatively constant funding, a Federal Advisory Committee (Committee) was chartered and reviewed the BBL program in 2005. The final report of the Committee included six major goals and 58 specific recommendations, 47 of which have been addressed by the BBL. Specifically, the Committee recommended the BBL continue to support science

  19. Marxismo e filosofia: algumas considerações sobre os textos políticos Merleau-Pontyanos do pós-guerra

    Directory of Open Access Journals (Sweden)

    Cristina Diniz Mendonça

    1987-01-01

    Full Text Available A tentativa merleau-pontyana de aproximação do marxismo, empreendida nos idos do pós-guerra, é perpassada por constante ambigüidade. Não obstante o propósito do filósofo de se filiar à teoria de Marx, suas análises políticas revelam-se distantes de suas intenções. Concebendo a história como uma "aventura" que escapa a qualquer esquema racional, Merleau-Ponty questiona, desde seus primeiros escritos, a dialética marxista entre lógica e contingência na história. A tensão interna que dilacera os textos do autor nos anos 40, anunciando (e preparando a recusa da teoria da revolução estampada mais tarde nas Aventuras da Dialética, permite indagar se esse desfecho dos anos 50 não teria sido, ao invés de um corte no interior da obra, o resultado necessário dessa tentativa problemática de aproximação do marxismo a partir de categorias que lhe são estranhas (próprias às filosofias da existência e à fenomenologia.

  20. The Dallas-Fort Worth (DFW) Urban Radar Network: Enhancing Resilience in the Presence of Floods, Tornadoes, Hail and High Winds

    Science.gov (United States)

    Chandra*, Chandrasekar V.; the full DFW Team

    2015-04-01

    Currently, the National Weather Service (NWS) Next Generation Weather Radar (NEXRAD) provides observations updated every five-six minutes across the United States. However, at the maximum NEXRAD operating range of 230 km, the 0.5 degree radar beam (lowest tilt) height is about 5.4 km above ground level (AGL) because of the effect of Earth curvature. Consequently, much of the lower atmosphere (1-3 km AGL) cannot be observed by the NEXRAD. To overcome the fundamental coverage limitations of today's weather surveillance radars, and improve the spatial and temporal resolution issues, at urban scale, the National Science Foundation Engineering Research Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) has embarked the development of Dallas-Fort worth (DFW) urban remote sensing network to conduct high-resolution sensing in the lower atmosphere for a metropolitan environment, communicate high resolution observations and nowcasting of severe weather including flash floods, hail storms and high wind events. Being one of the largest inland metropolitan areas in the U.S., the DFW Metroplex is home to over 6.5 million people by 2012 according to the North Central Texas Council of Governments (NCTCOG). It experiences a wide range of natural weather hazards, including urban flash flood, high wind, tornado, and hail, etc. Successful monitoring of the rapid changing meteorological conditions in such a region is necessary for emergency management and decision making. Therefore, it is an ideal location to investigate the impacts of hazardous weather phenomena, to enhance resilience in an urban setting and demonstrate the CASA concept in a densely populated urban environment. The DFW radar network consists of 8 dual-polarization X-band weather radars and standard NEXRAD S-band radar, covering the greater DFW metropolitan region. This paper will present high resolution observation of tornado, urban flood, hail storm and damaging wind event all within the

  1. Millimeter-wave silicon-based ultra-wideband automotive radar transceivers

    Science.gov (United States)

    Jain, Vipul

    Since the invention of the integrated circuit, the semiconductor industry has revolutionized the world in ways no one had ever anticipated. With the advent of silicon technologies, consumer electronics became light-weight and affordable and paved the way for an Information-Communication-Entertainment age. While silicon almost completely replaced compound semiconductors from these markets, it has been unable to compete in areas with more stringent requirements due to technology limitations. One of these areas is automotive radar sensors, which will enable next-generation collision-warning systems in automobiles. A low-cost implementation is absolutely essential for widespread use of these systems, which leads us to the subject of this dissertation---silicon-based solutions for automotive radars. This dissertation presents architectures and design techniques for mm-wave automotive radar transceivers. Several fully-integrated transceivers and receivers operating at 22-29 GHz and 77-81 GHz are demonstrated in both CMOS and SiGe BiCMOS technologies. Excellent performance is achieved indicating the suitability of silicon technologies for automotive radar sensors. The first CMOS 22-29-GHz pulse-radar receiver front-end for ultra-wideband radars is presented. The chip includes a low noise amplifier, I/Q mixers, quadrature voltage-controlled oscillators, pulse formers and variable-gain amplifiers. Fabricated in 0.18-mum CMOS, the receiver achieves a conversion gain of 35-38.1 dB and a noise figure of 5.5-7.4 dB. Integration of multi-mode multi-band transceivers on a single chip will enable next-generation low-cost automotive radar sensors. Two highly-integrated silicon ICs are designed in a 0.18-mum BiCMOS technology. These designs are also the first reported demonstrations of mm-wave circuits with high-speed digital circuits on the same chip. The first mm-wave dual-band frequency synthesizer and transceiver, operating in the 24-GHz and 77-GHz bands, are demonstrated. All

  2. ARM Cloud Radar Simulator Package for Global Climate Models Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuying [North Carolina State Univ., Raleigh, NC (United States); Xie, Shaocheng [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-01

    It has been challenging to directly compare U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility ground-based cloud radar measurements with climate model output because of limitations or features of the observing processes and the spatial gap between model and the single-point measurements. To facilitate the use of ARM radar data in numerical models, an ARM cloud radar simulator was developed to converts model data into pseudo-ARM cloud radar observations that mimic the instrument view of a narrow atmospheric column (as compared to a large global climate model [GCM] grid-cell), thus allowing meaningful comparison between model output and ARM cloud observations. The ARM cloud radar simulator value-added product (VAP) was developed based on the CloudSat simulator contained in the community satellite simulator package, the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) (Bodas-Salcedo et al., 2011), which has been widely used in climate model evaluation with satellite data (Klein et al., 2013, Zhang et al., 2010). The essential part of the CloudSat simulator is the QuickBeam radar simulator that is used to produce CloudSat-like radar reflectivity, but is capable of simulating reflectivity for other radars (Marchand et al., 2009; Haynes et al., 2007). Adapting QuickBeam to the ARM cloud radar simulator within COSP required two primary changes: one was to set the frequency to 35 GHz for the ARM Ka-band cloud radar, as opposed to 94 GHz used for the CloudSat W-band radar, and the second was to invert the view from the ground to space so as to attenuate the beam correctly. In addition, the ARM cloud radar simulator uses a finer vertical resolution (100 m compared to 500 m for CloudSat) to resolve the more detailed structure of clouds captured by the ARM radars. The ARM simulator has been developed following the COSP workflow (Figure 1) and using the capabilities available in COSP

  3. Monsoon Convection during the South China Sea Monsoon Experiment Observed from Shipboard Radar and the TRMM Satellite

    Science.gov (United States)

    Rickenbach, Tom; Cifelli, Rob; Halverson, Jeff; Kucera, Paul; Atkinson, Lester; Fisher, Brad; Gerlach, John; Harris, Kathy; Kaufman, Cristina; Liu, Ching-Hwang; hide

    1999-01-01

    A main goal of the recent South China Sea Monsoon Experiment (SCSMEX) was to study convective processes associated with the onset of the Southeast Asian summer monsoon. The NASA TOGA C-band scanning radar was deployed on the Chinese research vessel Shi Yan #3 for two 20 day cruises, collecting dual-Doppler measurements in conjunction with the BMRC C-Pol dual-polarimetric radar on Dongsha Island. Soundings and surface meteorological data were also collected with an NCAR Integrated Sounding System (ISS). This experiment was the first major tropical field campaign following the launch of the Tropical Rainfall Measuring Mission (TRMM) satellite. These observations of tropical oceanic convection provided an opportunity to make comparisons between surface radar measurements and the Precipitation Radar (PR) aboard the TRMM satellite in an oceanic environment. Nearly continuous radar operations were conducted during two Intensive Observing Periods (IOPS) straddling the onset of the monsoon (5-25 May 1998 and 5-25 June 1998). Mesoscale lines of convection with widespread regions of both trailing and forward stratiform precipitation were observed during the active monsoon periods in a southwesterly flow regime. Several examples of mesoscale convection will be shown from ship-based and spacebome radar reflectivity data during times of TRMM satellite overpasses. Further examples of pre-monsoon convection, characterized by isolated cumulonimbus and shallow, precipitating congestus clouds, will be discussed. A strong waterspout was observed very near the ship from an isolated cell in the pre-monsoon period, and was well documented with photography, radar, sounding, and sounding data.

  4. Space Radar Image of Wenatchee, Washington

    Science.gov (United States)

    1994-01-01

    This spaceborne radar image shows a segment of the Columbia River as it passes through the area of Wenatchee, Washington, about 220 kilometers (136 miles) east of Seattle. The Wenatchee Mountains, part of the Cascade Range, are shown in green at the lower left of the image. The Cascades create a 'rain shadow' for the region, limiting rainfall east of the range to less than 26 centimeters (10 inches) per year. The radar's ability to see different types of vegetation is highlighted in the contrast between the pine forests, that appear in green and the dry valley plain that shows up as dark purple. The cities of Wenatchee and East Wenatchee are the grid-like areas straddling the Columbia River in the left center of the image. With a population of about 60,000, the region produces about half of Washington state's lucrative apple crop. Several orchard areas appear as green rectangular patches to the right of the river in the lower right center. Radar images such as these can be used to monitor land use patterns in areas such as Wenatchee, that have diverse and rapidly changing urban, agricultural and wild land pressures. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 10, 1994. The image is 38 kilometers by 45 kilometers (24 miles by 30 miles) and is centered at 47.3 degrees North latitude, 120.1 degrees West longitude. North is toward the upper left. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  5. High-resolution mapping of wetland vegetation biomass and distribution with L-band radar in southeastern coastal Louisiana

    Science.gov (United States)

    Thomas, N. M.; Simard, M.; Byrd, K. B.; Windham-Myers, L.; Castaneda, E.; Twilley, R.; Bevington, A. E.; Christensen, A.

    2017-12-01

    Louisiana coastal wetlands account for approximately one third (37%) of the estuarine wetland vegetation in the conterminous United States, yet the spatial distribution of their extent and aboveground biomass (AGB) is not well defined. This knowledge is critical for the accurate completion of national greenhouse gas (GHG) inventories. We generated high-resolution baselines maps of wetland vegetation extent and biomass at the Atchafalaya and Terrebonne basins in coastal Louisiana using a multi-sensor approach. Optical satellite data was used within an object-oriented machine learning approach to classify the structure of wetland vegetation types, offering increased detail over currently available land cover maps that do not distinguish between wetland vegetation types nor account for non-permanent seasonal changes in extent. We mapped 1871 km2 of wetlands during a period of peak biomass in September 2015 comprised of flooded forested wetlands and leaf, grass and emergent herbaceous marshes. The distribution of aboveground biomass (AGB) was mapped using JPL L-band Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). Relationships between time-series radar imagery and field data collected in May 2015 and September 2016 were derived to estimate AGB at the Wax Lake and Atchafalaya deltas. Differences in seasonal biomass estimates reflect the increased AGB in September over May, concurrent with periods of peak biomass and the onset of the vegetation growing season, respectively. This method provides a tractable means of mapping and monitoring biomass of wetland vegetation types with L-band radar, in a region threatened with wetland loss under projections of increasing sea-level rise and terrestrial subsidence. Through this, we demonstrate a method that is able to satisfy the IPCC 2013 Wetlands Supplement requirement for Tier 2/Tier 3 reporting of coastal wetland GHG inventories.

  6. Leer lo estético desde lo político

    Directory of Open Access Journals (Sweden)

    Verónica Peñafiel

    2013-06-01

    Full Text Available En el Ecuador, y específicamente en la vida política del país, el teatro ha jugado un papel más importante del que se le ha reconocido. Pensar lo estético relacionado con lo político, puede ser una interesante clave de lectura para el teatro quiteño y, me arriesgo a afirmar, para el teatro a secas. Este análisis no se lo hará desde el teatro político, se pretende, más bien, analizar la dimensión política del mismo y de la relación entre teatro y política. Dicha dimensión política ha tomado diversas caras. Con los matices posibles, ha pasado de las salas a la calle, del costumbrismo a lo grotesco, de las compañías a los grupos. Comprender estos matices con la óptica de lo político puede dar pistas para articular una lógica estética del teatro quiteño

  7. Titan’s mid-latitude surface regions with Cassini VIMS and RADAR

    Science.gov (United States)

    Solomonidou, Anezina; Lopes, Rosaly M. C.; Coustenis, Athena; Malaska, Michael; Rodriguez, Sebastien; Maltagliati, Luca; Drossart, Pierre; Janssen, Michael; Lawrence, Kenneth; Jaumann, Ralf; Sohl, Frank; Stephan, Katrin; Brown, Robert H.; Bratsolis, Emmanuel; Matsoukas, Christos

    2015-11-01

    The Cassini-Huygens mission instruments have revealed Titan to have a complex and dynamic atmosphere and surface. Data from the remote sensing instruments have shown the presence of diverse surface terrains in terms of morphology and composition, suggesting both exogenic and endogenic processes [1]. We define both the surface and atmospheric contributions in the VIMS spectro-imaging data by use of a radiative transfer code in the near-IR range [2]. To complement this dataset, the Cassini RADAR instrument provides additional information on the surface morphology, from which valuable geological interpretations can be obtained [3]. We examine the origin of key Titan terrains, covering the mid-latitude zones extending from 50ºN to 50ºS. The different geological terrains we investigate include: mountains, plains, labyrinths, craters, dune fields, and possible cryovolcanic and/or evaporite features. We have found that the labyrinth terrains and the undifferentiated plains seem to consist of a very similar if not the same material, while the different types of plains show compositional variations [3]. The processes most likely linked to their formation are aeolian, fluvial, sedimentary, lacustrine, in addition to the deposition of atmospheric products though the process of photolysis and sedimentation of organics. We show that temporal variations of surface albedo exist for two of the candidate cryovolcanic regions. The surface albedo variations together with the presence of volcanic-like morphological features suggest that the active regions are possibly related to the deep interior, possibly via cryovolcanism processes (with important implications for the satellite’s astrobiological potential) as also indicated by new interior structure models of Titan and corresponding calculations of the spatial pattern of maximum tidal stresses [4]. However, an explanation attributed to exogenic processes is also possible [5]. We will report on results from our most recent

  8. Determination of the flat band potential for In sub 2 S sub 3 /electrolyte interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Herrasti, P; Fatas, E [Universidad Autonoma, Madrid (ES). Dept. de Quimica; Herrero, J; Ortega, J [CIEMAT, Madrid (ES). Inst. de Energias Renovables

    1990-02-01

    Flat band potentials V{sub fb} of In{sub 2}S{sub 3} polycrystalline thin films obtained by chalcogenization of electroplated metallic indium films on Ti substrates with a flowing stream of H{sub 2}S gas have been obtained. The variation of this potential with different redox couples, solution concentration and pH values has been studied. Photoelectrochemical characterization of the electrodes was accomplished in aqueous polysulphide solutions and the application of the Gartner-Butler model to the semiconductor/electrolyte interface makes it possible to obtain the semiconductor energy gap. The value obtained is 2.06 eV, corresponding to a direct allowed transition. (author).

  9. 40-Gb/s PDM-QPSK signal transmission over 160-m wireless distance at W-band.

    Science.gov (United States)

    Xiao, Jiangnan; Yu, Jianjun; Li, Xinying; Xu, Yuming; Zhang, Ziran; Chen, Long

    2015-03-15

    We experimentally demonstrate a W-band optical-wireless transmission system over 160-m wireless distance with a bit rate up to 40 Gb/s. The optical-wireless transmission system adopts optical polarization-division-multiplexing (PDM), multiple-input multiple-output (MIMO) reception and antenna polarization diversity. Using this system, we experimentally demonstrate the 2×2 MIMO wireless delivery of 20- and 40-Gb/s PDM quadrature-phase-shift-keying (PDM-QPSK) signals over 640- and 160-m wireless links, respectively. The bit-error ratios (BERs) of these transmission systems are both less than the forward-error-correction (FEC) threshold of 3.8×10-3.

  10. Computer-aided design of the RF-cavity for a high-power S-band klystron

    Science.gov (United States)

    Kant, D.; Bandyopadhyay, A. K.; Pal, D.; Meena, R.; Nangru, S. C.; Joshi, L. M.

    2012-08-01

    This article describes the computer-aided design of the RF-cavity for a S-band klystron operating at 2856 MHz. State-of-the-art electromagnetic simulation tools SUPERFISH, CST Microwave studio, HFSS and MAGIC have been used for cavity design. After finalising the geometrical details of the cavity through simulation, it has been fabricated and characterised through cold testing. Detailed results of the computer-aided simulation and cold measurements are presented in this article.

  11. Wave Height Estimation from Shadowing Based on the Acquired X-Band Marine Radar Images in Coastal Area

    Directory of Open Access Journals (Sweden)

    Yanbo Wei

    2017-08-01

    Full Text Available In this paper, the retrieving significant wave height from X-band marine radar images based on shadow statistics is investigated, since the retrieving accuracy can not be seriously affected by environmental factors and the method has the advantage of without any external reference to calibrate. However, the accuracy of the significant wave height estimated from the radar image acquired at the near-shore area is not ideal. To solve this problem, the effect of water depth is considered in the theoretical derivation of estimated wave height based on the sea surface slope. And then, an improved retrieving algorithm which is suitable for both in deep water area and shallow water area is developed. In addition, the radar data are sparsely processed in advance in order to achieve high quality edge image for the requirement of shadow statistic algorithm, since the high resolution radar images will lead to angle-blurred for the image edge detection and time-consuming in the estimation of sea surface slope. The data acquired from Pingtan Test Base in Fujian Province were used to verify the effectiveness of the proposed algorithm. The experimental results demonstrate that the improved method which takes into account the water depth is more efficient and effective and has better performance for retrieving significant wave height in the shallow water area, compared to the in situ buoy data as the ground truth and that of the existing shadow statistic method.

  12. A coleta seletiva como política pública na gestão de resíduos sólidos urbanos – o caso da cidade do Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Vinícius Ferreira Baptista

    2013-09-01

    Full Text Available Este estudo analisa a coleta seletiva como política pública. Primeiramente é contextualizada a questão dos custos na gestão dos resíduos, notadamente com ênfase sobre os lixões clandestinos. Após, indicamos as políticas públicas que tratam da matéria. Paralelamente, contextualizamos o cenário da gestão dos resíduos no âmbito da cidade do Rio de janeiro, a partir de dados e indicadores estatísticos de fontes governamentais e não governamentais, assim como destacamos os atores influentes nas políticas e programas voltados à coleta seletiva. Concluímos que a coleta seletiva vem sendo aplicada não como instrumento de gestão da Política Nacional de Resíduos Sólidos, mas como política pública em si.

  13. A PROFILE ANALYSIS OF RAMAN-SCATTERED O VI BANDS AT 6825 Å AND 7082 Å IN SANDULEAK’S STAR

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Jeong-Eun; Lee, Hee-Won [Department of Physics and Astronomy, Sejong University, Seoul (Korea, Republic of); Angeloni, Rodolfo [Gemini Observatory, Casilla 603, La Serena (Chile); Mille, Francesco Di [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Palma, Tali, E-mail: jeung6145@gmail.com [Departamento de Ciencias Físicas, Universidad Andrés Bello, Fernández Concha 700, Las Condes, Santiago (Chile)

    2016-12-20

    We present a detailed modeling of the two broad bands observed at 6825 and 7082 Å in Sanduleak’s star, a controversial object in the Large Magellanic Cloud. These bands are known to originate from Raman scattering of O vi  λ λ 1032 and 1038 photons with atomic hydrogen and are only observed in bona fide symbiotic stars. Our high-resolution spectrum obtained with the Magellan Inamori Kyocera Echelle spectrograph at the Magellan-Clay Telescope reveals, quite surprisingly, that the profiles of the two bands look very different: while the Raman 6825 Å band shows a single broad profile with a redward extended bump, the Raman 7082 Å band exhibits a distinct triple-peak profile. Our model suggests that the O vi emission nebula can be decomposed into a red, blue, and central emission region from an accretion disk, a bipolar outflow, and a further compact, optically thick region. We also perform Monte Carlo simulations with the aim of fitting the observed flux ratio F (6825)/ F (7082) ∼ 4.5, which indicates that the neutral region in Sanduleak’s star is characterized by the column density N{sub Hi} ∼ 1 × 10{sup 23} cm{sup −2}.

  14. Optical properties of GaS:Ho3+ and GaS:Tm3+ single crystals

    International Nuclear Information System (INIS)

    Jin, Moon-Seog; Kim, Chang-Dae; Kim, Wha-Tek

    2004-01-01

    GaS:Ho 3+ and GaS:Tm 3+ single crystals were grown by using the chemical transport reaction method. We measured the optical absorption, the infra-red absorption, and the photoluminescence spectra of the single crystals. The direct and the indirect energy band gaps of the single crystals at 13 K were identified. Infra-red absorption peaks at 6 K appeared in the single crystals. Broad emission bands at 6 K were observed at 464 nm and 580 nm for GaS:Ho 3+ and 462 nm and 581 nm for GaS:Tm 3+ . These broad emission bands were identified as originating from donor-acceptor pair recombinations. Sharp emission peak groups were observed near 435 nm, 495 nm, and 660 nm for GaS:Ho 3+ and near 672 nm for GaS:Tm 3+ . These sharp emission peak groups were identified as being due to the electron transitions between the energy levels of Ho 3+ and Tm 3+ . Especially, white photoluminescence was obtained in the GaS:Ho 3+ single crystal.

  15. Multi-wavelength fiber laser in the S-band region using a Sagnac loop mirror as a comb generator in an SOA gain medium

    International Nuclear Information System (INIS)

    Zulkifli, M Z; Hassan, N A; Awang, N A; Ahmad, H; Ghani, Z A; Harun, S W

    2010-01-01

    A simple design of multi-wavelength generation in the S-band region of the optical network transmission is proposed. The design consists of broad-band fiber Bragg grating (BB-FBG), which acts as a filter to enhance operation in the S-band region. A Sagnac loop mirror (SLM) is used to generate multiple wavelength oscillations in the ring cavity. The output consists of 60 lasing wavelengths oscillating simultaneously between 1464 nm and 1521 nm with a spacing of 0.92 nm and an output linewidth of 0.66 nm

  16. Gas And Ice Spectrometer/Radar (GAISR): a new instrument for close-up comet activity observations

    Science.gov (United States)

    Cooper, Ken; Monje, Raquel; Cochrane, Corey; Tang, Adrian; Alonso, Maria; Dengler, Robert; Durden, Stephen; Choukroun, Mathieu

    2017-10-01

    The Rosetta mission at 67P/Churyumov-Gerasimenko enabled the first detailed and long-term survey of cometary activity, which occurs primarily through water outgassing and emission of dust. Its highly-capable instrument suite improved our understanding of the outgassing and the dust emission and size distribution separately, however the coupling between the two remains poorly understood. GAISR consists of a dual-channel submillimeter-wave spectrometer inspired from MIRO/Rosetta, coupled to a small-particle Doppler radar for simultaneous observations of outgassing and emission of the large dust particles (comprising most of the mass emitted) in cometary jets and plumes of outer solar system satellites. GAISR’s medium-range W-band (95 GHz) radar will operate in a frequency-modulated continuous-wave (FMCW) mode with 1 Watt of transmit power to achieve high sensitivity detection of the range and velocity distribution of 0.1-10 mm sized ice and dust particles released by jets and plumes. The radar’s primary aperture also functions as an antenna for two passive heterodyne spectrometer channels at 270 and 560 GHz for detecting the abundance, temperature, and velocity of water vapor and its isotopes (including HDO), as well other major cometary volatiles such as CO, NH3, CH3OH. GAISR has been designed with a priority placed on low mass and power needs, to facilitate its infusion in future planetary missions. This is accomplished by leveraging recent innovations in W-band signal generation using low power silicon integrated circuits, state-of-the art III-V semiconductor devices for signal amplification and detection, and compact quasioptical duplexing. A new signal processing algorithm for FMCW Doppler radar detection out to the maximum range ambiguity limit has also been developed. GAISR’s performance testing has begun, and this poster will summarize its proven capabilities and plans for validation in relevant environments.

  17. The electronic band parameters calculated by the Kronig-Penney method for Cd1-xZnxS quantum dot superlattices

    International Nuclear Information System (INIS)

    Sakly, A.; Safta, N.; Mejri, H.; Lamine, A. Ben

    2009-01-01

    This work reports on a theoretical study of superlattices based on Cd 1-x Zn x S quantum dots embedded in an insulating material. We show, in particular, how this system can be assumed to a series of flattened cylindrical quantum dots with a finite barrier height at the boundary. In this paper, are also reviewed the approximations needed to calculate the band edges of the Cd 1-x Zn x S superlattices with use of the Kronig-Penney model. The electronic states and the electron effective masses of both Γ 1 - and Γ 2 -minibands have been computed as a function of zinc composition for different inter-quantum dot separations. As is found, the CdS system is appropriate to give rise a superlattice behavior for conduction electrons in a relatively large range of inter-sheet separations. An attempt to explain the electron band parameters calculated will be presented.

  18. El sistema westfaliano: un análisis desde la teología política de Nicolás Gómez Dávila

    OpenAIRE

    Molina, Tomás Felipe

    2016-01-01

    Resumen En este artículo, se quieren analizar las características principales del sistema westfaliano a partir de la teología política que Nicolás Gómez Dávila desarrolla en Textos I. Principalmente, se intentará mostrar que los Estados westfa- lianos toman los atributos de Dios y sustituyen a la divinidad en el papel que tenía en la Edad Media: reclaman para sí mismos la soberanía y la fundamentación axiológica y ontológica de los elementos del sistema. A partir de lo anterior, el artículo p...

  19. Application of high precision two-way S-band ranging to the navigation of the Galileo Earth encounters

    Science.gov (United States)

    Pollmeier, Vincent M.; Kallemeyn, Pieter H.; Thurman, Sam W.

    1993-01-01

    The application of high-accuracy S/S-band (2.1 GHz uplink/2.3 GHz downlink) ranging to orbit determination with relatively short data arcs is investigated for the approach phase of each of the Galileo spacecraft's two Earth encounters (8 December 1990 and 8 December 1992). Analysis of S-band ranging data from Galileo indicated that under favorable signal levels, meter-level precision was attainable. It is shown that ranginging data of sufficient accuracy, when acquired from multiple stations, can sense the geocentric angular position of a distant spacecraft. Explicit modeling of ranging bias parameters for each station pass is used to largely remove systematic ground system calibration errors and transmission media effects from the Galileo range measurements, which would otherwise corrupt the angle finding capabilities of the data. The accuracy achieved using the precision range filtering strategy proved markedly better when compared to post-flyby reconstructions than did solutions utilizing a traditional Doppler/range filter strategy. In addition, the navigation accuracy achieved with precision ranging was comparable to that obtained using delta-Differenced One-Way Range, an interferometric measurement of spacecraft angular position relative to a natural radio source, which was also used operationally.

  20. Una religión más vivida y una vida más religiosa. Testimonio: un movimiento de seglares en Colombia, 1947-1957

    Directory of Open Access Journals (Sweden)

    Andrés Mauricio Escobar Herrera

    2008-01-01

    Full Text Available Este artículo recupera la experiencia de un grupo de seglares comprometidos en su fe, quienes a mediados del siglo xx tomaron parte de las discusiones de la Iglesia católica sobre la participación de los fieles en política. Aunque esta agrupación se resistió a experimentar el tránsito hacia la configuración partidista, hizo las veces, en Colombia, de un movimiento religioso-político. Con el lema de “una religión más vivida y una vida más religiosa”, el movimiento Testimonio intervino en los debates de la política colombiana de las décadas del 40 y el 50, desarrollando un tipo particular de acción política católica apoyada en una comprometida militancia religiosa.

  1. Duas questões permanentes em um século de políticas de saúde no Brasil republicano Two permanent issues in a century of health policies in Republican Brazil

    Directory of Open Access Journals (Sweden)

    Madel Therezinha Luz

    2000-01-01

    Full Text Available Este artigo discute o tema da centralização versus descentralização das políticas de saúde do Estado brasileiro no século XX. Desenvolve como hipótese central a idéia de que a questão centralização/descentralização de serviços e funções nas políticas públicas, incluindo a de saúde, exprime no Estado a concentração do poder social na sociedade brasileira. A dicotomia centralização/descentralização seria a transposição institucional da concentração/desconcentração do poder social e sua tradução na ordem política. A centralização no Estado materializa a estrutura de concentração do poder institucional, que as políticas públicas exprimem, durante quase todo o século XX, apesar das interferências de vários movimentos da sociedade civil. Analisando as políticas de saúde em diversas conjunturas, e destacando a progressiva diversificação de atores políticos que nelas intervêm, o artigo conclui pela existência de um processo de efetiva descentralização nas políticas na década de 1990, embora sem uma verdadeira desconcentração do poder político.This article discusses the dilemma centralization versus decentralization in health policies of the republican Brazilian State during the twentieth century. It develops the central hypothesis that the dichotomy centralization/ decentralization of functions, services and activities in Brazilian public policies, mainly in the health policies, expresses the concentration/deconcentration dichotomy of social power in civil society. The centralization/decentralization dichotomy as it appears in health policies since the foundation of Brazilian republic, illustrates the authoritarian character of this republic, as a consequence of the concentration of the social power in the hands of a small elite. Analysis of health policies in different conjunctures seems to demonstrate that decentralization tends to be defined by the state and other political actors in a

  2. Nazismo, Socialismo e as políticas de direita e esquerda na primeira metade do século XX

    Directory of Open Access Journals (Sweden)

    Bertone de Oliveira Sousa

    2016-02-01

    Full Text Available Alguns trabalhos que discutem o tema do nazismo o situam como ideologia e movimento político de esquerda. Argumentam que seu caráter revolucionário, o uso do substantivo socialismo em sua sigla e o controle da economia pelo Estado, entre outras questões, são elementos que reforçam essa definição. Neste artigo, é feita uma problematização histórica dessas questões no sentido de mostrar por que o nazismo era uma ideologia de direita e para isso também são traçados alguns paralelos entre a Alemanha de Hitler e a União Soviética de Stalin, para mostrar como alguns elementos que caracterizavam o nazi-fascismo não estavam presentes com a mesma intensidade e os mesmos significados fora de seu arcabouço ideológico e de ação.

  3. Piezo-phototronic Effect Enhanced UV/Visible Photodetector Based on Fully Wide Band Gap Type-II ZnO/ZnS Core/Shell Nanowire Array.

    Science.gov (United States)

    Rai, Satish C; Wang, Kai; Ding, Yong; Marmon, Jason K; Bhatt, Manish; Zhang, Yong; Zhou, Weilie; Wang, Zhong Lin

    2015-06-23

    A high-performance broad band UV/visible photodetector has been successfully fabricated on a fully wide bandgap ZnO/ZnS type-II heterojunction core/shell nanowire array. The device can detect photons with energies significantly smaller (2.2 eV) than the band gap of ZnO (3.2 eV) and ZnS (3.7 eV), which is mainly attributed to spatially indirect type-II transition facilitated by the abrupt interface between the ZnO core and ZnS shell. The performance of the device was further enhanced through the piezo-phototronic effect induced lowering of the barrier height to allow charge carrier transport across the ZnO/ZnS interface, resulting in three orders of relative responsivity change measured at three different excitation wavelengths (385, 465, and 520 nm). This work demonstrates a prototype UV/visible photodetector based on the truly wide band gap semiconducting 3D core/shell nanowire array with enhanced performance through the piezo-phototronic effect.

  4. Estimating snow water equivalent (SWE) using interferometric synthetic aperture radar (InSAR)

    Science.gov (United States)

    Deeb, Elias J.

    Since the early 1990s, radar interferometry and interferometric synthetic aperture radar (InSAR) have been used extensively to measure changes in the Earth's surface. Previous research has presented theory for estimating snow properties, including potential for snow water equivalent (SWE) retrieval, using InSAR. The motivation behind using remote sensing to estimate SWE is to provide a more complete, continuous set of "observations" to assist in water management operations, climate change studies, and flood hazard forecasting. The research presented here primarily investigates the feasibility of using the InSAR technique at two different wavelengths (C-Band and L-Band) for SWE retrieval of dry snow within the Kuparuk watershed, North Slope, Alaska. Estimating snow distribution around meteorological towers on the coastal plain using a three-day repeat orbit of C-Band InSAR data was successful (Chapter 2). A longer wavelength L-band SAR is evaluated for SWE retrievals (Chapter 3) showing the ability to resolve larger snow accumulation events over a longer period of time. Comparisons of InSAR estimates and late spring manual sampling of SWE show a R2 = 0.61 when a coherence threshold is used to eliminate noisy SAR data. Qualitative comparisons with a high resolution digital elevation model (DEM) highlight areas of scour on windward slopes and areas of deposition on leeward slopes. When compared to a mid-winter transect of manually sampled snow depths, the InSAR SWE estimates yield a RMSE of 2.21cm when a bulk snow density is used and corrections for bracketing the satellite acquisition timing is performed. In an effort to validate the interaction of radar waves with a snowpack, the importance of the "dry snow" assumption for the estimation of SWE using InSAR is tested with an experiment in Little Cottonwood Canyon, Alta, Utah (Chapter 5). Snow wetness is shown to have a significant effect on the velocity of propagation within the snowpack. Despite the radar

  5. Dynamic gauge adjustment of high-resolution X-band radar data for convective rain storms: Model-based evaluation against measured combined sewer overflow

    Science.gov (United States)

    Borup, Morten; Grum, Morten; Linde, Jens Jørgen; Mikkelsen, Peter Steen

    2016-08-01

    Numerous studies have shown that radar rainfall estimates need to be adjusted against rain gauge measurements in order to be useful for hydrological modelling. In the current study we investigate if adjustment can improve radar rainfall estimates to the point where they can be used for modelling overflows from urban drainage systems, and we furthermore investigate the importance of the aggregation period of the adjustment scheme. This is done by continuously adjusting X-band radar data based on the previous 5-30 min of rain data recorded by multiple rain gauges and propagating the rainfall estimates through a hydraulic urban drainage model. The model is built entirely from physical data, without any calibration, to avoid bias towards any specific type of rainfall estimate. The performance is assessed by comparing measured and modelled water levels at a weir downstream of a highly impermeable, well defined, 64 ha urban catchment, for nine overflow generating rain events. The dynamically adjusted radar data perform best when the aggregation period is as small as 10-20 min, in which case it performs much better than static adjusted radar data and data from rain gauges situated 2-3 km away.

  6. Up to 40 Gb/s wireless signal generation and demodulation in 75-110 GHz band using photonic techniques

    DEFF Research Database (Denmark)

    Sambaraju, R.; Zibar, Darko; Caballero Jambrina, Antonio

    2010-01-01

    Record wireless signal capacity of up to 40 Gb/s is demonstrated in the 75-110 GHz band. All-optical OFDM and photonic up-conversion are used for generation and digital coherent detection for demodulation....

  7. Mode S data link transponder flight test results

    Science.gov (United States)

    1997-02-01

    The Federal Aviation Administration (FAA) William J. Hughes Technical Center is : in the unique position of having the facilities designed to test Mode S radars : and transponders. A vendor supplied an early production model of a Mode S : transponder...

  8. Charles Tilly: Legado y estela De The Vendée a Contentious Performances, para comprender el conflicto político del s. XIX español Charles Tilly: Legado y estela De The Vendée a Contentious Performances, para comprender el conflicto político del s. XIX español

    Directory of Open Access Journals (Sweden)

    Gloria Martínez Dorado

    2010-07-01

    Full Text Available Charles Tilly’s later work sums up, assesses, specifies and projects into the future the theoretical and empirical legacy of a life of study devoted to Historical Sociology. From his masterpiece opera prima, The Vendée, on to his latest Contentious politics, Tilly developed a vast array of theoretical concepts, which he provided with extensive and precise empirical referents (among them, we may cite: performance, collective action repertoire, political opportunity structure, mechanisms for mobilization and, finally, worthiness, unity, numbers and commitment. Today, these notions are located at the very core of the sociological/historical studies about political contention in early Modern Europe. Tilly’s preference for quantitative and comparative methods was subservient to his interest in giving account of, not the motivational Why?, but the objective How, When and What for of collective mobilization; not in explanatory ‘laws’ of historical change, but in analytically fecund descriptions of similar, but also unique historical episodes. This article adopts the methodological paradigm Tilly first developed when writing The Vendée, analytically updated throughout his later work, as theoretical framework for a new approach of the social and political mobilization that led to the first Carlista war. Specifically, the mechanisms for mobilization that provided material and human resources for the war effort are researched in three different Navarre villages –selected by their differing economic, cultural, and politically features.Las últimas obras de Charles Tilly recapitulan, evalúan, concretan y proyectan hacia el futuro el legado empírico y teórico de una vida dedicada a la sociología histórica. Desde su opera prima sobre la Vendée hasta Contienda política y democracia en Europa, Tilly desarrolló y dio amplio y preciso contenido empírico a un conjunto de conceptos teóricos que hoy vertebran los estudios del conflicto pol

  9. Políticas efectivas para reducir la mortalidad infantil en el Perú: ¿Cómo reducir la mortalidad infantil en las zonas más pobres del país?

    OpenAIRE

    Beltrán, Arlette; Grippa Zárate, Ana Rosa

    2014-01-01

    El propósito del presente trabajo es hallar aquellos determinantes más efectivos para reducir la mortalidad neonatal e infantil, para que sean utilizados como variables de política por el «policymaker» y se pueda alcanzar el Objetivo de Desarrollo del Milenio # 4: reducir para el año 2015 la tasa de mortalidad infantil a un tercio de su valor inicial de 1992. El trabajo hace uso de dos bases de datos: la IV Encuesta Demográfica y de Salud Familiar (Endes, 2000) y el II Censo de Infraestructur...

  10. Drake Antarctic Agile Meteor Radar (DrAAMER) First Results: Configuration and Comparison of Mean and Tidal Wind and Gravity Wave Momentum Flux Measurements with SAAMER

    Science.gov (United States)

    Fritts, D. C.; Janches, D.; Iimura, H.; Hocking, W. K.; Bageston, J. V.; Pene, N. M.

    2011-01-01

    A new-generation meteor radar was installed at the Brazilian Antarctic Comandante Ferraz Base (62.1degS) in March 2010. This paper describes the motivations for the radar location, its measurement capabilities, and comparisons of measured mean winds, tides, and gravity wave momentum fluxes from April to June of 2010 and 2011 with those by a similar radar on Tierra del Fuego (53.8degS). Motivations for the radars include the "hotspot" of small-scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere (MLT) centered over the Drake Passage, the maximum of the semidiurnal tide at these latitudes, and the lack of other MLT wind measurements in this latitude band. Mean winds are seen to be strongly modulated at planetary wave and longer periods and to exhibit strong coherence over the two radars at shorter time scales as well as systematic seasonal variations. The semidiurnal tide contribute most to the large-scale winds over both radars, with maximum tidal amplitudes during May and maxima at the highest altitudes varying from approx.20 to >70 m/s. In contrast, the diurnal tide and various planetary waves achieve maximum winds of approx.10 to 20 m/s. Monthly-mean gravity wave momentum fluxes appear to reflect the occurrence of significant sources at lower altitudes, with relatively small zonal fluxes over both radars, but with significant, and opposite, meridional momentum fluxes below approx.85 km. These suggest gravity waves propagating away from the Drake Passage at both sites, and may indicate an important source region accounting in part for this "hotspot".

  11. German Radar Observation Shuttle Experiment (ROSE)

    Science.gov (United States)

    Sleber, A. J.; Hartl, P.; Haydn, R.; Hildebrandt, G.; Konecny, G.; Muehlfeld, R.

    1984-01-01

    The success of radar sensors in several different application areas of interest depends on the knowledge of the backscatter of radar waves from the targets of interest, the variance of these interaction mechanisms with respect to changing measurement parameters, and the determination of the influence of he measuring systems on the results. The incidence-angle dependency of the radar cross section of different natural targets is derived. Problems involved by the combination of data gained with different sensors, e.g., MSS-, TM-, SPOTand SAR-images are analyzed. Radar cross-section values gained with ground-based radar spectrometers and spaceborne radar imaging, and non-imaging scatterometers and spaceborne radar images from the same areal target are correlated. The penetration of L-band radar waves into vegetated and nonvegetated surfaces is analyzed.

  12. Bunch Compressor Beamlines for the Tesla and S Band Linear Colliders

    CERN Document Server

    Emma, P

    2003-01-01

    A detailed design for a single stage beam bunch length compressor for both the TESLA and the S-Band Linear Collider (SBLC) is presented. Compression is achieved by introducing an energy-position correlation along the bunch with an rf section at zero-crossing phase followed by a short bending section with energy dependent path length (momentum compaction). The motivation for a wiggler design is presented and many of the critical single bunch tolerances are evaluated. A solenoid based spin rotator is included in the design and transverse emittance tuning elements, diagnostics and tuning methods are described. Bunch length limitations due to second order momentum compaction and sinusoidal rf shape are discussed with options for compensation. Finally, the disadvantages of bunch compression using a 180 sup o arc are discussed.

  13. Heterochromatin diversity and its co-localization with 5S and 45S rDNA sites in chromosomes of four Maxillaria species (Orchidaceae

    Directory of Open Access Journals (Sweden)

    Juliano S. Cabral

    2006-01-01

    Full Text Available We investigated four orchids of the genus Maxillaria (M. discolor, M. acicularis, M. notylioglossa and M. desvauxiana in regard to the position of heterochromatin blocks as revealed using chromomycin A3 (CMA and 4'-6-diamidino-2-phenylindole (DAPI fluorochrome staining and 5S and 45S rDNA sites using fluorescence in situ hybridization (FISH. The species showed differences in chromosome number and a diversified pattern of CMA+ and DAPI+ bands, including heteromorphism for CMA+ bands. The 5S and 45S rDNA sites also varied in number and most of them were co-localized with CMA+ bands. The relationship between 5S rDNA sites and CMA+ bands was more evident in M. notylioglossa, in which the brighter CMA+ bands were associated with large 5S rDNA sites. However, not all 5S and 45S rDNA sites were co-localized with CMA+ bands, probably due to technical constraints. We compare these results to banding data from other species and suggest that not all blocks of tandemly repetitive sequences, such as 5S rDNA sites, can be observed as heterochromatin blocks.

  14. Observation of dark-current signals from the S-band structures of the SLAC linac

    International Nuclear Information System (INIS)

    Assmann, R.; Decker, F.J.; Seidel, M.; Siemann, R.H.; Whittum, D.

    1997-07-01

    It is well known that the electro-magnetic fields in high-gradient RF structures can cause electron emission from the metallic structure walls. If the emitted electrons are captured and accelerated by the accelerating fields so-called dark-current is induced. Dark-currents have been measured and studied for various RF-structures. In this paper the authors present measurements of RF induced signals for the SLC S-band structures. For nominal gradients of 17 MV/m it is shown that the dark-current can be strong enough to significantly reduce the signal-to-noise ratio of the SLC beam wire scanners. They also show results from RF measurements in the dipole band. The measurements are compared to more direct observations of dark-current and it is tried to connect the results to possible effects on the accelerated particle beam

  15. High Resolution Radar Imaging using Coherent MultiBand Processing Techniques

    NARCIS (Netherlands)

    Dorp, Ph. van; Ebeling, R.P.; Huizing, A.G.

    2010-01-01

    High resolution radar imaging techniques can be used in ballistic missile defence systems to determine the type of ballistic missile during the boost phase (threat typing) and to discriminate different parts of a ballistic missile after the boost phase. The applied radar imaging technique is 2D

  16. Legitimidad y democracia en el México contemporáneo : estudio del cambio político conceptual a través de los discursos de algunos intelectuales mexicanos : Cuadernos Americanos, Plural, Vuelta y Letras Libres

    OpenAIRE

    Contreras Alcántara, Javier

    2010-01-01

    El objetivo de la investigación es entender la configuración político-conceptual sobre la “legitimidad política” y la “democracia” en México a través del análisis de las reflexiones de algunos intelectuales mexicanos agrupados en las publicaciones Cuadernos Americanos, Plural, Vuelta y Letras Libres, así como también de los discursos del gobierno a través de discursos e informes presidenciales, durante el periodo comprendido entre 1946 y 2006. Se busca esclarecer la trayectoria conceptual de ...

  17. A facile inexpensive route for SnS thin film solar cells with SnS{sub 2} buffer

    Energy Technology Data Exchange (ETDEWEB)

    Gedi, Sreedevi [School of Chemical Engineering, Yeungnam University, 280Daehak-ro, Gyeongsan 712-749, Republic of Korea (Korea, Republic of); Solar Photovoltaic Laboratory, Department of Physics, Sri Venkateswasra University, Tirupati 517 502 (India); Minna Reddy, Vasudeva Reddy, E-mail: drmvasudr9@gmail.com [School of Chemical Engineering, Yeungnam University, 280Daehak-ro, Gyeongsan 712-749, Republic of Korea (Korea, Republic of); Solar Photovoltaic Laboratory, Department of Physics, Sri Venkateswasra University, Tirupati 517 502 (India); Pejjai, Babu [School of Chemical Engineering, Yeungnam University, 280Daehak-ro, Gyeongsan 712-749, Republic of Korea (Korea, Republic of); Solar Photovoltaic Laboratory, Department of Physics, Sri Venkateswasra University, Tirupati 517 502 (India); Jeon, Chan-Wook [School of Chemical Engineering, Yeungnam University, 280Daehak-ro, Gyeongsan 712-749, Republic of Korea (Korea, Republic of); Park, Chinho, E-mail: chpark@ynu.ac.kr [School of Chemical Engineering, Yeungnam University, 280Daehak-ro, Gyeongsan 712-749, Republic of Korea (Korea, Republic of); Ramakrishna Reddy, K.T., E-mail: ktrkreddy@gmail.com [Solar Photovoltaic Laboratory, Department of Physics, Sri Venkateswasra University, Tirupati 517 502 (India)

    2016-05-30

    Graphical abstract: PYS spectra of SnS/SnS{sub 2} interface and the related band diagram. - Highlights: • A low cost SnS solar cell is developed using chemical bath deposition. • We found E{sub I} & χ of SnS (5.3 eV & 4.0 eV) and SnS{sub 2} (6.9 eV & 4.1 eV) films from PYS. • Band offsets of 0.1 eV (E{sub c}) and 1.6 eV (E{sub v}) are estimated for SnS/SnS{sub 2} junction. • SnS based solar cell showed a conversion efficiency of 0.51%. - Abstract: Environment-friendly SnS based thin film solar cells with SnS{sub 2} as buffer layer were successfully fabricated from a facile inexpensive route, chemical bath deposition (CBD). Layer studies revealed that as-grown SnS and SnS{sub 2} films were polycrystalline; (1 1 1)/(0 0 1) peaks as the preferred orientation; 1.3 eV/2.8 eV as optical band gaps; and showed homogeneous microstructure with densely packed grains respectively. Ionization energy and electron affinity values were found by applying photoemission yield spectroscopy (PYS) to the CBD deposited SnS and SnS{sub 2} films for the first time. These values obtained as 5.3 eV and 4.0 eV for SnS films; 6.9 eV and 4.1 eV for SnS{sub 2} films. The band alignment of SnS/SnS{sub 2} junction showed TYPE-II heterostructure. The estimated conduction and valance band offsets were 0.1 eV and 1.6 eV respectively. The current density–voltage (J–V) measurements of the cell showed open circuit voltage (V{sub oc}) of 0.12 V, short circuit current density (J{sub sc}) of 10.87 mA cm{sup −2}, fill factor (FF) of 39% and conversion efficiency of 0.51%.

  18. A Polícia e suas Polícias: Clientela, Hierarquia, Soldado e Bandido

    Directory of Open Access Journals (Sweden)

    Erika Ferreira de Azevedo

    Full Text Available Resumo A polícia militar representa um braço do Estado e apresenta-se para a população de forma contundente, ostensiva e, por vezes, brutal, não só para a sociedade como para ela mesma. Através da Análise Institucional do Discurso, a pesquisa aqui relatada teve como objetivo estudar os efeitos de reconhecimento e desconhecimento das relações no trabalho que permeiam o discurso de soldados da polícia militar: como estes falam de seu trabalho e, através desta fala, posicionam-se e posicionam sua clientela, sua hierarquia, seu objeto de trabalho (os “bandidos” e eles próprios. Buscou-se também analisar que lugar a violência ocupou neste discurso. Dez soldados da polícia militar do Estado de São Paulo foram entrevistados e a transcrição destas estrevistas foi analisada. A partir das análises, é possível refletir sobre a dubiedade do verdadeiro objetivo do trabalho policial, deslizando facilmente do cuidado da população desamparada ao cuidado de si, desamparado sob a pressão da farda.

  19. Experimentelles FMCW-Radar zur hochfrequenten Charakterisierung von Windenergieanlagen

    Science.gov (United States)

    Schubert, Karsten; Werner, Jens; Schwartau, Fabian

    2017-09-01

    During the increasing dissemination of renewable energy sources the potential and actual interference effects of wind turbine plants became obvious. Turbines reflect the signals of weather radar and other radar systems. In addition to the static radar echoes, in particular the Doppler echoes are to be mentioned as an undesirable impairment Keränen (2014). As a result, building permit is refused for numerous new wind turbines, as the potential interference can not be reliably predicted. As a contribution to the improvement of this predictability, measurements are planned which aim at the high-frequency characterisation of wind energy installations. In this paper, a cost-effective FMCW radar is presented, which is operated in the same frequency band (C-band) as the weather radars of the German weather service. Here, the focus is on the description of the hardware design including the considerations used for its dimensioning.

  20. La creación política: con y más allá de Cornelius Castoriadis

    Directory of Open Access Journals (Sweden)

    Profumi, Emanuele

    2013-12-01

    Full Text Available What does “political creation” mean? If we draw this general idea by highlighting contemporary philosopher C. Castoriadis thought about the project of autonomy referring to the social-historical process that produced the birth of the “polis” of Athens, thanks to the Greek political imaginary, and the French Revolution, starting from the transformation of the medieval religious society, then we can show which logical-ontological assumptions are the basis of this idea, as well as its specific and general condition and its actual expression, from the point of view of the praxis of social-historical transformation. To arrive at this result we need to evaluate critically the main ideas that Cornelius Castoriadis connects with the idea and the practice of autonomy, particularly the concepts of social-historical and politics. In this respect, we will be able to find, within Aldo Capitini’s practical philosophy of religion, the confirmation of a credible ethical-political transposition of the above-mentioned assumptions.¿Qué significa “la creación política”? Si deducimos esta idea general valorizando el discurso del filosofo contemporáneo Cornelius Castodiadis, cuando habla de proyecto de autonomía refiriéndose al proceso social-histórico donde nace la polis de Atenas, gracias al imaginario político griego, y donde se produce la revolución francesa a partir de la fin del cambio de la sociedad religiosa de la Edad Media, entonces podemos mostrar cuales son las presuposiciones lógica-ontológicas que constituyen las raíces de esta idea. Podemos aclarar su condición especifica y su condición general, como también su expresión concreta a nivel de praxis de transformación social-histórica. Para llegar a este resultado es necesario analizar críticamente las ideas principales que Castoriadis conecte con la idea y la práctica de autonomía, y, en particular, las ideas de social-histórico y de política. Encontrando en la

  1. Optically Discriminating Carrier-Induced Quasiparticle Band Gap and Exciton Energy Renormalization in Monolayer MoS_{2}.

    Science.gov (United States)

    Yao, Kaiyuan; Yan, Aiming; Kahn, Salman; Suslu, Aslihan; Liang, Yufeng; Barnard, Edward S; Tongay, Sefaattin; Zettl, Alex; Borys, Nicholas J; Schuck, P James

    2017-08-25

    Optoelectronic excitations in monolayer MoS_{2} manifest from a hierarchy of electrically tunable, Coulombic free-carrier and excitonic many-body phenomena. Investigating the fundamental interactions underpinning these phenomena-critical to both many-body physics exploration and device applications-presents challenges, however, due to a complex balance of competing optoelectronic effects and interdependent properties. Here, optical detection of bound- and free-carrier photoexcitations is used to directly quantify carrier-induced changes of the quasiparticle band gap and exciton binding energies. The results explicitly disentangle the competing effects and highlight longstanding theoretical predictions of large carrier-induced band gap and exciton renormalization in two-dimensional semiconductors.

  2. Optically Discriminating Carrier-Induced Quasiparticle Band Gap and Exciton Energy Renormalization in Monolayer MoS2

    Science.gov (United States)

    Yao, Kaiyuan; Yan, Aiming; Kahn, Salman; Suslu, Aslihan; Liang, Yufeng; Barnard, Edward S.; Tongay, Sefaattin; Zettl, Alex; Borys, Nicholas J.; Schuck, P. James

    2017-08-01

    Optoelectronic excitations in monolayer MoS2 manifest from a hierarchy of electrically tunable, Coulombic free-carrier and excitonic many-body phenomena. Investigating the fundamental interactions underpinning these phenomena—critical to both many-body physics exploration and device applications—presents challenges, however, due to a complex balance of competing optoelectronic effects and interdependent properties. Here, optical detection of bound- and free-carrier photoexcitations is used to directly quantify carrier-induced changes of the quasiparticle band gap and exciton binding energies. The results explicitly disentangle the competing effects and highlight longstanding theoretical predictions of large carrier-induced band gap and exciton renormalization in two-dimensional semiconductors.

  3. A flux transfer event observed at the magnetopause by the Equator-S spacecraft and in the ionosphere by the CUTLASS HF radar

    Directory of Open Access Journals (Sweden)

    D. A. Neudegg

    1999-06-01

    Full Text Available Observations of a flux transfer event (FTE have been made simultaneously by the Equator-S spacecraft near the dayside magnetopause whilst corresponding transient plasma flows were seen in the near-conjugate polar ionosphere by the CUTLASS Finland HF radar. Prior to the occurrence of the FTE, the magnetometer on the WIND spacecraft ~226 RE upstream of the Earth in the solar wind detected a southward turning of the interplanetary magnetic field (IMF which is estimated to have reached the subsolar magnetopause ~77 min later. Shortly afterwards the Equator-S magnetometer observed a typical bipolar FTE signature in the magnetic field component normal to the magnetopause, just inside the magnetosphere. Almost simultaneously the CUTLASS Finland radar observed a strong transient flow in the F region plasma between 78° and 83° magnetic latitude, near the ionospheric region predicted to map along geomagnetic field lines to the spacecraft. The flow signature (and the data set as a whole is found to be fully consistent with the view that the FTE was formed by a burst of magnetopause reconnection.Key words. Interplanetary physics (ionosphere-magnetosphere interaction · Magnetospheric physics (magnetopause · cusp · and boundary layers; solar wind-magnetosphere interactions

  4. Dynamic gauge adjustment of high-resolution X-band radar data for convective rain storms: Model-based evaluation against measured combined sewer overflow

    DEFF Research Database (Denmark)

    Borup, Morten; Grum, Morten; Linde, Jens Jørgen

    2016-01-01

    estimates through a hydraulic urban drainage model. The model is built entirely from physical data, without any calibration, to avoid bias towards any specific type of rainfall estimate. The performance is assessed by comparing measured and modelled water levels at a weir downstream of a highly impermeable......Numerous studies have shown that radar rainfall estimates need to be adjusted against rain gauge measurements in order to be useful for hydrological modelling. In the current study we investigate if adjustment can improve radar rainfall estimates to the point where they can be used for modelling...... overflows from urban drainage systems, and we furthermore investigate the importance of the aggregation period of the adjustment scheme. This is done by continuously adjusting X-band radar data based on the previous 5–30 min of rain data recorded by multiple rain gauges and propagating the rainfall...

  5. Extracting bird migration information from C-band Doppler weather radars

    NARCIS (Netherlands)

    van Gasteren, H.; Holleman, I.; Bouten, W.; van Loon, E.; Shamoun-Baranes, J.

    2008-01-01

    Although radar has been used in studies of bird migration for 60 years, there is still no network in Europe for comprehensive monitoring of bird migration. Europe has a dense network of military air surveillance radars but most systems are not directly suitable for reliable bird monitoring. Since

  6. La subjetividad política y la socialización política, desde las márgenes de la psicología política

    Directory of Open Access Journals (Sweden)

    Sara Victoria Alvarado

    2012-01-01

    Full Text Available Se trata de un trabajo en el que abordamos inicialmente una tematización de la psicología política, desde sus antecedentes históricos generales, sus investigaciones más significativas, las categorías emblemáticas de su campo de estudio y su horizonte de desarrollo en Latinoamérica, a través de lo cual identificamos el marco disciplinar desde donde se construyen las categorías de la socialización y de la subjetividad política como núcleos conceptuales, señalando los límites de la visión solipsista disciplinar y su imposibilidad de recoger la multisémica complejidad de dichas categorías, por lo cual se hace necesario emprender la vía de su deconstrucción histórica, tratando de identificar sus relaciones categoriales transdisciplinares, más allá de las márgenes de la misma psicología política.

  7. Distributed feedback multimode Brillouin–Raman random fiber laser in the S-band

    International Nuclear Information System (INIS)

    Ahmad, H; Zulkifli, M Z; Jemangin, M H; Harun, S W

    2013-01-01

    A novel S-band multimode Brillouin–Raman random fiber laser based on distributed feedback of Rayleigh scattered light is demonstrated. It relies on a short length, 7.7 km long angle-cleaved dispersion compensating fiber in a mirror-less open cavity. Two 1425 nm laser diodes at a modest operating power amplify a Brillouin pump (BP) signal, which in turn generates a multi-wavelength laser output through the stimulated Brillouin scattering. Eleven Brillouin Stokes lines, spanning from 1515.15 to 1516.00 nm, were obtained at a Raman pump power of 361.66 mW. Out of these, five odd Brillouin Stokes lines were generated with a flat peak power of about 0 dBm. (letter)

  8. Towards Snowpack Characterization using C-band Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    Park, J.; Forman, B. A.

    2017-12-01

    Sentinel 1A and 1B, operated by the European Space Agency (ESA), carries a C-band synthetic aperture radar (SAR) sensor that can be used to monitor terrestrial snow properties. This study explores the relationship between terrestrial snow-covered area, snow depth, and snow water equivalent with Sentinel 1 backscatter observations in order to better characterize snow mass. Ground-based observations collected by the National Oceanic and Atmospheric Administration - Cooperative Remote Sensing Science and Technology Center (NOAA-CREST) in Caribou, Maine in the United States are also used in the comparative analysis. Sentinel 1 Ground Range Detected (GRD) imagery with Interferometric Wide swath (IW) were preprocessed through a series of steps accounting for thermal noise, sensor orbit, radiometric calibration, speckle filtering, and terrain correction using ESA's Sentinel Application Platform (SNAP) software package, which is an open-source module written in Python. Comparisons of dual-polarized backscatter coefficients (i.e., σVV and σVH) with in-situ measurements of snow depth and SWE suggest that cross-polarized backscatter observations exhibit a modest correlation between both snow depth and SWE. In the case of the snow-covered area, a multi-temporal change detection method was used. Results using Sentinel 1 yield similar spatial patterns as when using hyperspectral observations collected by the MODerate Resolution Imaging Spectroradiometer (MODIS). These preliminary results suggest the potential application of Sentinel 1A/1B backscatter coefficients towards improved discrimination of snow cover, snow depth, and SWE. One goal of this research is to eventually merge C-band SAR backscatter observations with other snow information (e.g., passive microwave brightness temperatures) as part of a multi-sensor snow assimilation framework.

  9. O envelhecimento populacional sob o viés do controle jurisdicional de políticas públicas para os idosos O ENVELHECIMENTO POPULACIONAL SOB O VIÉS DO CONTROLE JURISDICIONAL DE POLÍTICAS PÚBLICAS PARA OS IDOSOS

    Directory of Open Access Journals (Sweden)

    Andréia Garcia Martin

    2011-04-01

    Full Text Available

    Através do presente pretende-se analisar o envelhecimento populacional e o seu impacto nas relações de âmbito social e jurídico para com as pessoas que ultrapassaram a barreira dos sessenta anos que, por não mais deterem a capacidade de produzir riquezas, quedam-se às margens da sociedade. Demonstrando-se que aos idosos são inerentes todos e quaisquer direitos consignados a todas as pessoas. E o Estatuto do Idoso como um documento social busca conscientizar a sociedade de modo geral sobre o processo biológico do envelhecimento, bem como seus reflexos em todos os segmentos da sociedade. Necessitando essa camada da população de prestações dos Poderes de Estado que concretize seu direito fundamental social à saúde para que possam envelhecer dignamente. Robustecendo-se a atuação do Poder Judiciário, que diante da inércia dos Poderes competentes para implementar as necessárias políticas públicas de saúde para os idosos, que através do controle jurisdicional dessas políticas efetiva o direito á saúde desse segmento populacional incluído-os socialmente, e garantindo condições dignas de existência.

    Atraves do Presente Pretende- se analisar o Envelhecimento populacional EO Seu Impacto NAS RELAÇÕES de Âmbito Social e com parágrafo Jurídico o PESSOAS ultrapassaram Que uma Barreira dos Sessenta Que Anos , Por nao Mais deterem uma CAPACIDADE de Produzir Riquezas , quedam - se Às Margens Sociedade da . Demonstrando - se Que EAo Idosos de São inerentes Todos Direitos quaisquer e Consignados uma Todas As PESSOAS . E o Estatuto do Idoso Documento hum Como

  10. Vertical Pointing Weather Radar for Built-up Urban Areas

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Thorndahl, Søren; Schaarup-Jensen, Kjeld

    2008-01-01

      A cost effective vertical pointing X-band weather radar (VPR) has been tested for measurement of precipitation in urban areas. Stationary tests indicate that the VPR performs well compared to horizontal weather radars, such as the local area weather radars (LAWR). The test illustrated...

  11. Radar observations of Mercury

    International Nuclear Information System (INIS)

    Harmon, J.K.; Campbell, D.B.

    1988-01-01

    Some of the radar altimetry profiles of Mercury obtained on the basis of data from the Arecibo Observatory are presented. In these measurements, the delay-Doppler method was used to measure altitudes along the Doppler equator, rather than to map radar reflectivity. The profiles, derived from observations made over a 6-yr period, provide extensive coverage over a restricted equatorial band and permit the identification of radar signatures for features as small as 50-km diameter craters and 1-km-high arcuate scarps. The data allowed identification of large-scale topographic features such as smooth plains subsidence zones and major highland regions

  12. Chemically deposited In2S3–Ag2S layers to obtain AgInS2 thin films by thermal annealing

    International Nuclear Information System (INIS)

    Lugo, S.; Peña, Y.; Calixto-Rodriguez, M.; López-Mata, C.; Ramón, M.L.; Gómez, I.; Acosta, A.

    2012-01-01

    Highlights: ► We obtained polycrystalline silver indium sulfide thin films through the annealing of chemically deposited In 2 S 3 –Ag 2 S films. ► According to XRD chalcopyrite structure of AgInS 2 was obtained. ► AgInS 2 thin film has a band gap of 1.86 eV and a conductivity value of 1.2 × 10 −3 (Ω cm) −1 . - Abstract: AgInS 2 thin films were obtained by the annealing of chemical bath deposited In 2 S 3 –Ag 2 S layers at 400 °C in N 2 for 1 h. According to the XRD and EDX results the chalcopyrite structure of AgInS 2 has been obtained. These films have an optical band gap, E g , of 1.86 eV and an electrical conductivity value of 1.2 × 10 −3 (Ω cm) −1 .

  13. Solid State KA-Band, Solid State W-Band and TWT Amplifiers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Phase I of the proposal describes plans to develop a state of the art transmitter for the W-Band and KA -Band Cloud Radar system. Our focus will be concentrated in...

  14. 1-Pb/s (32 SDM/46 WDM/768 Gb/s) C-band Dense SDM Transmission over 205.6-km of Single-mode Heterogeneous Multi-core Fiber using 96-Gbaud PDM-16QAM Channels

    DEFF Research Database (Denmark)

    Kobayashi, Takayuki; Nakamura, M.; Hamaoka, F.

    2017-01-01

    We demonstrate the first 1-Pb/s unidirectional inline-amplified transmission over 205.6-km of single-mode 32-core fiber within C-band only. 96-Gbaud LDPC-coded PDM-16QAM channels with FEC redundancy of 12.75% realize high-aggregate spectral efficiency of 217.6 b/s/Hz...

  15. Efficient Ways to Learn Weather Radar Polarimetry

    Science.gov (United States)

    Cao, Qing; Yeary, M. B.; Zhang, Guifu

    2012-01-01

    The U.S. weather radar network is currently being upgraded with dual-polarization capability. Weather radar polarimetry is an interdisciplinary area of engineering and meteorology. This paper presents efficient ways to learn weather radar polarimetry through several basic and practical topics. These topics include: 1) hydrometeor scattering model…

  16. A controvérsia nestoriana e suas implicações político-administrativas nas cartas de Cirilo de Alexandria (séc. V d.c.)

    OpenAIRE

    Figueiredo, Daniel de [UNESP

    2012-01-01

    A presente pesquisa visa demonstrar, através da correspondência epistolar do bispo Cirilo de Alexandria, as implicações político-religiosas e administrativas que circundaram o conflito, ocorrido no Império Romano do Oriente, na primeira metade do século V d.C. e que ficou conhecido pela historiografia por Controvérsia Nestoriana. À primeira leitura daqueles documentos, somos direcionados a entender o referido conflito apenas na perspectiva de uma querela teológica entre Cirilo e Nestório, bis...

  17. Isolados 'como nós' ou isolados 'entre nós'?: a polêmica na Academia Nacional de Medicina sobre o isolamento compulsório dos doentes de lepra Isolated 'like us' or isolated 'among us'?: the controversy within the National Academy of Medicine over compulsory isolation of leprosy sufferers

    Directory of Open Access Journals (Sweden)

    Vivian da Silva Cunha

    2010-12-01

    Full Text Available Da forma como a lepra era percebida na sociedade brasileira do início do século XX, a segregação dos doentes era vista como o único modo de proteger os sãos. A política praticada pela Inspetoria de Profilaxia da Lepra e das Doenças Venéreas privilegiava o isolamento em leprosários. Belisário Penna, crítico à atuação desta Inspetoria, defendia que a melhor forma de isolar os doentes seria através da criação de municípios geograficamente distantes dos centros urbanos. Em 1926, instaurou-se uma polêmica entre Penna e Eduardo Rabello, ex-chefe da Inspetoria, sobre esse tema. Essa polêmica se configurou como parte de um debate mais geral sobre a melhor forma de se controlar a lepra, e nos permite entender as mudanças ocorridas na década de 1930 acerca das políticas implementadas contra a doença.Given Brazilian society's view of leprosy in the early twentieth century, patient segregation was considered the only way to protect the healthy. The policy enforced by the Inspectorship for the Prevention of Leprosy and Venereal Diseases deemed isolation in leprosaria the preferred approach. Belisário Penna criticized the work of the Inspectorship, arguing that the best way to isolate patients would be to create municipalities located a good distance from urban centers. In 1926, Penna came head to head over the subject with Eduardo Rabello, the Inspectorship's former chief. Part of a broader debate on the best way to control leprosy, this controversy sheds light on the changes to leprosy policies introduced in the 1930s.

  18. La defensa de presos políticos a comienzos de los ´70: ejercicio profesional, derecho y política

    OpenAIRE

    Chama, Mauricio

    2010-01-01

    El trabajo aborda la relación entre abogacía y política a comienzos de la década del '70. Más precisamente se propone identificar y reconstruir los principales rasgos que asume la defensa de presos políticos en ese período. Más que una labor específica, se entiende que la defensa de presos políticos en esos años representó una novedosa configuración que logró articular una nueva asociación de profesionales del derecho, renovadas estrategias de defensa, una vasta y sistemática labor de denunci...

  19. Determination of the valence-band offset of CdS/CIS solar cell devices by target factor analysis

    Energy Technology Data Exchange (ETDEWEB)

    Niles, D.W.; Contreras, M.; Ramanathan, K.; Noufi, R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    X-ray photoemission spectroscopy (XPS) is used to determine and compare the valence-band offsets ({Delta}E{sub v}) for CdS grown by chemical bath deposition on single-crystal and thin-film CuInSe{sub 2} (CIS). The thin-film CIS device was suitable for photovoltaic energy production. By sputtering through the CdS/CIS interface and reducing the depth profile with target factor analysis, the magnitude of {Delta}E{sub v} was determined to be {Delta}E{sub v} = 1.06 {+-} 0.15 eV for both the single-crystal and thin-film interfaces. This determination of {Delta}E{sub v} is about 0.25 eV larger than many previously reported estimations CdS grown by physical vapor deposition on CIS and helps explain the record performance of CdS/CIS photovoltaic devices.

  20. 1×4 Optical packet switching of variable length 640 Gbit/s data packets using in-band optical notch-filter labeling

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros; Kamchevska, Valerija; Galili, Michael

    2014-01-01

    We experimentally perform 1×4 optical packet switching of variable length 640 Gbit/s OTDM data packets using in-band notch-filter labeling with only 2.7-dB penalty. Up to 8 notches are employed to demonstrate scalability of the labeling scheme to 1×256 switching operation.......We experimentally perform 1×4 optical packet switching of variable length 640 Gbit/s OTDM data packets using in-band notch-filter labeling with only 2.7-dB penalty. Up to 8 notches are employed to demonstrate scalability of the labeling scheme to 1×256 switching operation....

  1. Space Radar Image of West Texas - SAR scan

    Science.gov (United States)

    1999-01-01

    This radar image of the Midland/Odessa region of West Texas, demonstrates an experimental technique, called ScanSAR, that allows scientists to rapidly image large areas of the Earth's surface. The large image covers an area 245 kilometers by 225 kilometers (152 miles by 139 miles). It was obtained by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) flying aboard the space shuttle Endeavour on October 5, 1994. The smaller inset image is a standard SIR-C image showing a portion of the same area, 100 kilometers by 57 kilometers (62 miles by 35 miles) and was taken during the first flight of SIR-C on April 14, 1994. The bright spots on the right side of the image are the cities of Odessa (left) and Midland (right), Texas. The Pecos River runs from the top center to the bottom center of the image. Along the left side of the image are, from top to bottom, parts of the Guadalupe, Davis and Santiago Mountains. North is toward the upper right. Unlike conventional radar imaging, in which a radar continuously illuminates a single ground swath as the space shuttle passes over the terrain, a Scansar radar illuminates several adjacent ground swaths almost simultaneously, by 'scanning' the radar beam across a large area in a rapid sequence. The adjacent swaths, typically about 50 km (31 miles) wide, are then merged during ground processing to produce a single large scene. Illumination for this L-band scene is from the top of the image. The beams were scanned from the top of the scene to the bottom, as the shuttle flew from left to right. This scene was acquired in about 30 seconds. A normal SIR-C image is acquired in about 13 seconds. The ScanSAR mode will likely be used on future radar sensors to construct regional and possibly global radar images and topographic maps. The ScanSAR processor is being designed for 1996 implementation at NASA's Alaska SAR Facility, located at the University of Alaska Fairbanks, and will produce digital images from the

  2. Value of a dual-polarized gap-filling radar in support of southern California post-fire debris-flow warnings

    Science.gov (United States)

    Jorgensen, David P.; Hanshaw, Maiana N.; Schmidt, Kevin M.; Laber, Jayme L; Staley, Dennis M.; Kean, Jason W.; Restrepo, Pedro J.

    2011-01-01

    A portable truck-mounted C-band Doppler weather radar was deployed to observe rainfall over the Station Fire burn area near Los Angeles, California, during the winter of 2009/10 to assist with debris-flow warning decisions. The deployments were a component of a joint NOAA–U.S. Geological Survey (USGS) research effort to improve definition of the rainfall conditions that trigger debris flows from steep topography within recent wildfire burn areas. A procedure was implemented to blend various dual-polarized estimators of precipitation (for radar observations taken below the freezing level) using threshold values for differential reflectivity and specific differential phase shift that improves the accuracy of the rainfall estimates over a specific burn area sited with terrestrial tipping-bucket rain gauges. The portable radar outperformed local Weather Surveillance Radar-1988 Doppler (WSR-88D) National Weather Service network radars in detecting rainfall capable of initiating post-fire runoff-generated debris flows. The network radars underestimated hourly precipitation totals by about 50%. Consistent with intensity–duration threshold curves determined from past debris-flow events in burned areas in Southern California, the portable radar-derived rainfall rates exceeded the empirical thresholds over a wider range of storm durations with a higher spatial resolution than local National Weather Service operational radars. Moreover, the truck-mounted C-band radar dual-polarimetric-derived estimates of rainfall intensity provided a better guide to the expected severity of debris-flow events, based on criteria derived from previous events using rain gauge data, than traditional radar-derived rainfall approaches using reflectivity–rainfall relationships for either the portable or operational network WSR-88D radars. Part of the reason for the improvement was due to siting the radar closer to the burn zone than the WSR-88Ds, but use of the dual-polarimetric variables

  3. Band alignment of HfO{sub 2}/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy: Effect of CHF{sub 3} treatment

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinke; He, Jiazhu; Tang, Dan; Jia, Fang; Lu, Youming, E-mail: ymlu@szu.edu.cn; Zhu, Deliang; Liu, Wenjun; Cao, Peijiang; Han, Sun [College of Materials Science and Engineering, Shenzhen Engineering Laboratory for Advanced Technology of Ceramics, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Liu, Qiang; Wen, Jiao; Yu, Wenjie, E-mail: casan@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS,865 Chang Ning Road, Shanghai 200050 (China); Pan, Jisheng [Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore 117602 (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore)

    2015-09-07

    The energy band alignment between HfO{sub 2}/multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The HfO{sub 2} was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 1.98 eV and a conduction band offset (CBO) of 2.72 eV were obtained for the HfO{sub 2}/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the HfO{sub 2}/ML-MoS{sub 2} interface were found to be 2.47 eV and 2.23 eV, respectively. The band alignment difference is believed to be dominated by the down-shift in the core level of Hf 4d and up-shift in the core level of Mo 3d, or the interface dipoles, which caused by the interfacial layer in rich of F.

  4. Radar rainfall estimation for the identification of debris-flow precipitation thresholds

    Science.gov (United States)

    Marra, Francesco; Nikolopoulos, Efthymios I.; Creutin, Jean-Dominique; Borga, Marco

    2014-05-01

    Identification of rainfall thresholds for the prediction of debris-flow occurrence is a common approach for warning procedures. Traditionally the debris-flow triggering rainfall is derived from the closest available raingauge. However, the spatial and temporal variability of intense rainfall on mountainous areas, where debris flows take place, may lead to large uncertainty in point-based estimates. Nikolopoulos et al. (2014) have shown that this uncertainty translates into a systematic underestimation of the rainfall thresholds, leading to a step degradation of the performances of the rainfall threshold for identification of debris flows occurrence under operational conditions. A potential solution to this limitation lies on use of rainfall estimates from weather radar. Thanks to their high spatial and temporal resolutions, these estimates offer the advantage of providing rainfall information over the actual debris flow location. The aim of this study is to analyze the value of radar precipitation estimations for the identification of debris flow precipitation thresholds. Seven rainfall events that triggered debris flows in the Adige river basin (Eastern Italian Alps) are analyzed using data from a dense raingauge network and a C-Band weather radar. Radar data are elaborated by using a set of correction algorithms specifically developed for weather radar rainfall application in mountainous areas. Rainfall thresholds for the triggering of debris flows are identified in the form of average intensity-duration power law curves using a frequentist approach by using both radar rainfall estimates and raingauge data. Sampling uncertainty associated to the derivation of the thresholds is assessed by using a bootstrap technique (Peruccacci et al. 2012). Results show that radar-based rainfall thresholds are largely exceeding those obtained by using raingauge data. Moreover, the differences between the two thresholds may be related to the spatial characteristics (i.e., spatial

  5. Wind Retrieval Algorithms for the IWRAP and HIWRAP Airborne Doppler Radars with Applications to Hurricanes

    Science.gov (United States)

    Guimond, Stephen Richard; Tian, Lin; Heymsfield, Gerald M.; Frasier, Stephen J.

    2013-01-01

    Algorithms for the retrieval of atmospheric winds in precipitating systems from downward-pointing, conically-scanning airborne Doppler radars are presented. The focus in the paper is on two radars: the Imaging Wind and Rain Airborne Profiler(IWRAP) and the High-altitude IWRAP (HIWRAP). The IWRAP is a dual-frequency (Cand Ku band), multi-beam (incidence angles of 30 50) system that flies on the NOAAWP-3D aircraft at altitudes of 2-4 km. The HIWRAP is a dual-frequency (Ku and Kaband), dual-beam (incidence angles of 30 and 40) system that flies on the NASA Global Hawk aircraft at altitudes of 18-20 km. Retrievals of the three Cartesian wind components over the entire radar sampling volume are described, which can be determined using either a traditional least squares or variational solution procedure. The random errors in the retrievals are evaluated using both an error propagation analysis and a numerical simulation of a hurricane. These analyses show that the vertical and along-track wind errors have strong across-track dependence with values of 0.25 m s-1 at nadir to 2.0 m s-1 and 1.0 m s-1 at the swath edges, respectively. The across-track wind errors also have across-track structure and are on average, 3.0 3.5 m s-1 or 10 of the hurricane wind speed. For typical rotated figure four flight patterns through hurricanes, the zonal and meridional wind speed errors are 2 3 m s-1.Examples of measured data retrievals from IWRAP during an eyewall replacement cycle in Hurricane Isabel (2003) and from HIWRAP during the development of Tropical Storm Matthew (2010) are shown.

  6. Cross-linking of L5 protein to 5 S RNA in rat liver 60-S subunits by ultraviolet irradiation

    International Nuclear Information System (INIS)

    Terao, K.; Uchiumi, T.; Ogata, K.

    1980-01-01

    After rat liver 60-S ribosomal subunits were irradiated with ultraviolet light at 254 nm, they were treated with EDTA and then subjected to sucrose density-gradient centrifugation to isolate 5 S RNA-protein complex. When 5 S RNA-protein was analyzed by SDS-acrylamide gel electrophoresis which dissociated noncovalent 5 S RNA-protein, two protein bands were observed. The one showed a slower mobility than the protein band (L5) of 5 S RNA-protein from non-irradiated 60 S subunit and the other showed the same mobility as L5 protein. Since the former band was shown to be specific to ultraviolet-irradiation, it was considered as cross-linked 5 S RNA-protein. After the two protein bands were iodinated with 125 I, labeled protein was extracted and treated with RNAase. Thereafter, it was analyzed by two-dimensional acrylamide gel electrophoresis, followed by autoradiography. The results indicate that the protein component of cross-linked 5 S RNA-protein is L5 protein (ribosomal protein); these proteins are designated according to the proposed uniform nomenclature. (Auth.)

  7. No matarás ni con hambre ni con balas: las mujeres de los comedores populares autogestionarios en El Agustino durante la violencia política

    Directory of Open Access Journals (Sweden)

    Jacqueline Minaya Rodríguez

    2015-01-01

    Full Text Available Los comedores populares autogestionarios - CPA¹ tienen más de 35 años de existencia, desde 1978, a la cabeza de mujeres valerosas, en una Lima pobre, migrante y luchadora. Estas mujeres lucharon frente al Estado por derechos y reivindicaciones, como servicios básicos y políticas alimentarias. Las mujeres hicieron, de temas caseros, políticas públicas que lograron sostener, en gran medida, la crisis económica a fines de la década de 1980 e inicios de la de 1990, dando así muestras de organización a gran escala en un contexto sumamente difícil. En ese complicado panorama, convivieron con integrantes del grupo subversivo del Partido Comunista del Perú-Sendero Luminoso - PCP-SL, que incursionó en las barriadas para «profundizar las contradicciones» y aplicó, en nombre de la justicia, estrategias de guerra. La investigación rastrea las trayectorias de las exdirigentas de los CPA en el distrito limeño de El Agustino, y recoge sus testimonios sobre la violencia política que les tocó vivir entre 1978 y 1992² y sobre las problemáticas relaciones con el Estado. Esta convivencia produjo un complicado tejido de hilos muy delgados, donde las cercanías y lejanías de estas mujeres frente a Sendero Luminoso fueron parte de un proceso más complejo.

  8. Application of borehole radar to South Africa’s Ultra-Deep gold mining environment

    CSIR Research Space (South Africa)

    Trickett, JC

    2000-05-01

    Full Text Available ), the collar of which is located at a depth of 3.3 km below datum1. LIB boreholes are used to probe totally undeveloped blocks of ground and, being semi-parallel to reef, are ideal for the application of Borehole Radar. By applying Borehole Radar from... the target reef; viz. 1 For the Witwatersrand Basin Gold Mines, the datum is ? 1829 m above sea level. Ventersdorp Contact Reef (VCR), twice. It was drilled at 45? downwards into the hangingwall...

  9. The impact of the snow cover on sea-ice thickness products retrieved by Ku-band radar altimeters

    Science.gov (United States)

    Ricker, R.; Hendricks, S.; Helm, V.; Perovich, D. K.

    2015-12-01

    Snow on sea ice is a relevant polar climate parameter related to ocean-atmospheric interactions and surface albedo. It also remains an important factor for sea-ice thickness products retrieved from Ku-band satellite radar altimeters like Envisat or CryoSat-2, which is currently on its mission and the subject of many recent studies. Such satellites sense the height of the sea-ice surface above the sea level, which is called sea-ice freeboard. By assuming hydrostatic equilibrium and that the main scattering horizon is given by the snow-ice interface, the freeboard can be transformed into sea-ice thickness. Therefore, information about the snow load on hemispherical scale is crucial. Due to the lack of sufficient satellite products, only climatological values are used in current studies. Since such values do not represent the high variability of snow distribution in the Arctic, they can be a substantial contributor to the total sea-ice thickness uncertainty budget. Secondly, recent studies suggest that the snow layer cannot be considered as homogenous, but possibly rather featuring a complex stratigraphy due to wind compaction and/or ice lenses. Therefore, the Ku-band radar signal can be scattered at internal layers, causing a shift of the main scattering horizon towards the snow surface. This alters the freeboard and thickness retrieval as the assumption that the main scattering horizon is given by the snow-ice interface is no longer valid and introduces a bias. Here, we present estimates for the impact of snow depth uncertainties and snow properties on CryoSat-2 sea-ice thickness retrievals. We therefore compare CryoSat-2 freeboard measurements with field data from ice mass-balance buoys and aircraft campaigns from the CryoSat Validation Experiment. This unique validation dataset includes airborne laser scanner and radar altimeter measurements in spring coincident to CryoSat-2 overflights, and allows us to evaluate how the main scattering horizon is altered by the

  10. Energy Impacts of Wide Band Gap Semiconductors in U.S. Light-Duty Electric Vehicle Fleet.

    Science.gov (United States)

    Warren, Joshua A; Riddle, Matthew E; Graziano, Diane J; Das, Sujit; Upadhyayula, Venkata K K; Masanet, Eric; Cresko, Joe

    2015-09-01

    Silicon carbide and gallium nitride, two leading wide band gap semiconductors with significant potential in electric vehicle power electronics, are examined from a life cycle energy perspective and compared with incumbent silicon in U.S. light-duty electric vehicle fleet. Cradle-to-gate, silicon carbide is estimated to require more than twice the energy as silicon. However, the magnitude of vehicle use phase fuel savings potential is comparatively several orders of magnitude higher than the marginal increase in cradle-to-gate energy. Gallium nitride cradle-to-gate energy requirements are estimated to be similar to silicon, with use phase savings potential similar to or exceeding that of silicon carbide. Potential energy reductions in the United States vehicle fleet are examined through several scenarios that consider the market adoption potential of electric vehicles themselves, as well as the market adoption potential of wide band gap semiconductors in electric vehicles. For the 2015-2050 time frame, cumulative energy savings associated with the deployment of wide band gap semiconductors are estimated to range from 2-20 billion GJ depending on market adoption dynamics.

  11. Reforma do Estado e as políticas para a educação superior no Brasil nos anos 90 State Reforma and federal policies for higher education in Brazil in the 1990s

    Directory of Open Access Journals (Sweden)

    Luiz Fernandes Dourado

    2002-09-01

    Full Text Available O presente artigo propõe-se a discutir as políticas educacionais implementadas no Brasil nos anos 90, do século XX, no que concerne à educação superior. Nessa ótica, parte da compreensão de que tais políticas são demarcadas por opções e interesses sociopolíticos articulados às mudanças no cenário contemporâneo, que se traduzem na apreensão das determinantes históricas que balizam o processo de reforma do Estado brasileiro. Essa lógica implica alterações no campo das políticas públicas, especialmente das políticas sociais, na medida em que estão em curso propostas e projetos que se configuram pela minimização do papel do Estado, marcado pela interpenetração das esferas pública e privada em detrimento da primeira. As políticas para a educação superior, nesse cenário, são analisadas indicando-se seus paradoxos e seus desdobramentos efetivos no que concerne aos processos de diversificação e diferenciação institucional, sistema de avaliação, expansão e privatização desse nível de ensino.This article aims at discussing the federal policies for higher education implemented in Brazil in the 1990s. It assumes that such policies are based on socio-political choices and interests linked to the changes occurring in the contemporary Brazilian scene, changes that have deep historical roots, which emerge in the process of reformation of the Brazilian State. This situation implies alterations in the field of public policies, and more particularly in that of social policies, since the on-going official proposals and projects are characterized by a decrease of the role of State. The borders between public and private affairs have become increasingly blurred in a process detrimental to the former. The contradictions in the federal policies for higher education are analyzed here, as well as their results as for the following fields: institutional diversification and differentiation; assessment criteria, broadening and

  12. Space Radar Image of County Kerry, Ireland

    Science.gov (United States)

    1994-01-01

    The Iveragh Peninsula, one of the four peninsulas in southwestern Ireland, is shown in this spaceborne radar image. The lakes of Killarney National Park are the green patches on the left side of the image. The mountains to the right of the lakes include the highest peaks (1,036 meters or 3,400 feet) in Ireland. The patchwork patterns between the mountains are areas of farming and grazing. The delicate patterns in the water are caused by refraction of ocean waves around the peninsula edges and islands, including Skellig Rocks at the right edge of the image. The Skelligs are home to a 15th century monastery and flocks of puffins. The region is part of County Kerry and includes a road called the 'Ring of Kerry' that is one of the most famous tourist routes in Ireland. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the Space Shuttle Endeavour on April 12, 1994. The image is 82 kilometers by 42 kilometers (51 miles by 26 miles) and is centered at 52.0 degrees north latitude, 9.9 degrees west longitude. North is toward the lower left. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, vertically transmitted and received; and blue is C-band, vertically transmitted and received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  13. Raymond Aron ante el maquiavelismo político

    Directory of Open Access Journals (Sweden)

    Molina Cano, Jerónimo

    2008-08-01

    Full Text Available It is a simplification of Raymond Aron´s thought to consider him as a mere neo-liberal political thinker. The French sociologist, a well-known political realist, took part in the famous controversy about Machiavellianism that was Aron´s intellectual watershed from the Forties. Starting from that controversy the aim of the present paper is to inquire into his contribution to the so-called “moderate Machiavellianism”, whose Arcanum is that it is not always possible to choose the optimal means to face the right political action. Machiavellianism is not a merely scientific or epistemological question, but something that deeply determines all political actions.

    La presentación de Raymond Aron como un escritor político neoliberal constituye una simplificación de su pensamiento. El sociólogo francés, que pertenece a la tradición del realismo político, tuvo una destacada intervención en la famosa polémica sobre el maquiavelismo que marcó un punto de inflexión en su pensamiento. Este artículo examina su contribución a esa inagotable polémica intelectual desde los años 40 y constata, finalmente, su encuadramiento en el denominado “maquiavelismo moderado”, cuyo arcano político es que, en política, no siempre se pueden elegir los medios de la acción. El maquiavelismo no es, en este sentido, un asunto científico o epistemológico, sino que determina profundamente toda acción política.

  14. MAJOR SOURCE OF NEW RADAR DATA FOR EXPLORATION RESEARCH.

    Science.gov (United States)

    Kover, Allan N.; Jones, John Edwin; Southworth, C. Scott

    1984-01-01

    In 1980, the U. S. Geological Survey (USGS) initiated a program to acquire high-quality, side-looking, airborne-radar (SLAR) imagery of selected areas of the United States. The program goals were to demonstrate the usefulness of SLAR imagery for geologic exploration and geoscience applications and to make radar data readily available to the public for additional research and economic applications. Considerable SLAR imagery has been acquired already since 1980 under a mandate from the U. S. Congress. The U. S. Geological Survey is actively engaged in demonstrating the usefulness of radar imagery, and since 1980 has started more than 50 studies addressing geologic, cartographic, and hydrologic applications. All of the radar-imagery products acquired by the USGS during 1980 and 1982 have been archived and are available for public sale.

  15. Effective shunt impedance comparison between s-band standing wave accelerators with on-axis and off-axis couplers

    International Nuclear Information System (INIS)

    Schriber, S.O.; Funk, L.W.; Hutcheon, R.M.

    1976-01-01

    The effective shunt impedances of a side-coupled S-band standing wave accelerating structure and a structure employing on-axis couplers have been compared by measuring the energy of accelerated electrons. Criteria for choosing an on-axis coupled structure compared to side-coupled and ''disk and washer'' accelerating structures are given. (author)

  16. Inversion for atmosphere duct parameters using real radar sea clutter

    International Nuclear Information System (INIS)

    Sheng Zheng; Fang Han-Xian

    2012-01-01

    This paper addresses the problem of estimating the lower atmospheric refractivity (M profile) under nonstandard propagation conditions frequently encountered in low altitude maritime radar applications. The vertical structure of the refractive environment is modeled using five parameters and the horizontal structure is modeled using five parameters. The refractivity model is implemented with and without a priori constraint on the duct strength as might be derived from soundings or numerical weather-prediction models. An electromagnetic propagation model maps the refractivity structure into a replica field. Replica fields are compared with the observed clutter using a squared-error objective function. A global search for the 10 environmental parameters is performed using genetic algorithms. The inversion algorithm is implemented on the basis of S-band radar sea-clutter data from Wallops Island, Virginia (SPANDAR). Reference data are from range-dependent refractivity profiles obtained with a helicopter. The inversion is assessed (i) by comparing the propagation predicted from the radar-inferred refractivity profiles with that from the helicopter profiles, (ii) by comparing the refractivity parameters from the helicopter soundings with those estimated. This technique could provide near-real-time estimation of ducting effects. (geophysics, astronomy, and astrophysics)

  17. Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR) method.

    Science.gov (United States)

    Malashchonak, Mikalai V; Mazanik, Alexander V; Korolik, Olga V; Streltsov, Еugene А; Kulak, Anatoly I

    2015-01-01

    The photoelectrochemical properties of nanoheterostructures based on the wide band gap oxide substrates (ZnO, TiO2, In2O3) and CdS nanoparticles deposited by the successive ionic layer adsorption and reaction (SILAR) method have been studied as a function of the CdS deposition cycle number (N). The incident photon-to-current conversion efficiency (IPCE) passes through a maximum with the increase of N, which is ascribed to the competition between the increase in optical absorption and photocarrier recombination. The maximal IPCE values for the In2O3/CdS and ZnO/CdS heterostructures are attained at N ≈ 20, whereas for TiO2/CdS, the appropriate N value is an order of magnitude higher. The photocurrent and Raman spectroscopy studies of CdS nanoparticles revealed the occurrence of the quantum confinement effect, demonstrating the most rapid weakening with the increase of N in ZnO/CdS heterostructures. The structural disorder of CdS nanoparticles was characterized by the Urbach energy (E U), spectral width of the CdS longitudinal optical (LO) phonon band and the relative intensity of the surface optical (SO) phonon band in the Raman spectra. Maximal values of E U (100-120 meV) correspond to СdS nanoparticles on a In2O3 surface, correlating with the fact that the CdS LO band spectral width and intensity ratio for the CdS SO and LO bands are maximal for In2O3/CdS films. A notable variation in the degree of disorder of CdS nanoparticles is observed only in the initial stages of CdS growth (several tens of deposition cycles), indicating the preservation of the nanocrystalline state of CdS over a wide range of SILAR cycles.

  18. Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR method

    Directory of Open Access Journals (Sweden)

    Mikalai V. Malashchonak

    2015-11-01

    Full Text Available The photoelectrochemical properties of nanoheterostructures based on the wide band gap oxide substrates (ZnO, TiO2, In2O3 and CdS nanoparticles deposited by the successive ionic layer adsorption and reaction (SILAR method have been studied as a function of the CdS deposition cycle number (N. The incident photon-to-current conversion efficiency (IPCE passes through a maximum with the increase of N, which is ascribed to the competition between the increase in optical absorption and photocarrier recombination. The maximal IPCE values for the In2O3/CdS and ZnO/CdS heterostructures are attained at N ≈ 20, whereas for TiO2/CdS, the appropriate N value is an order of magnitude higher. The photocurrent and Raman spectroscopy studies of CdS nanoparticles revealed the occurrence of the quantum confinement effect, demonstrating the most rapid weakening with the increase of N in ZnO/CdS heterostructures. The structural disorder of CdS nanoparticles was characterized by the Urbach energy (EU, spectral width of the CdS longitudinal optical (LO phonon band and the relative intensity of the surface optical (SO phonon band in the Raman spectra. Maximal values of EU (100–120 meV correspond to СdS nanoparticles on a In2O3 surface, correlating with the fact that the CdS LO band spectral width and intensity ratio for the CdS SO and LO bands are maximal for In2O3/CdS films. A notable variation in the degree of disorder of CdS nanoparticles is observed only in the initial stages of CdS growth (several tens of deposition cycles, indicating the preservation of the nanocrystalline state of CdS over a wide range of SILAR cycles.

  19. Radar Spectrum Engineering and Management (Ingenierie et gestion du spectre radar)

    Science.gov (United States)

    2017-04-01

    of Kansas seguin@ku.edu Electrical Engr. & Comp. Sci. Dept. 1520 W. 15th Street Lawrence, KS 66045 UNITED STATES Nicolas SENTENAC...e t s t s t s tt w jt ψ= + = 1 2 2 1 ( ( ) ( ) tan ) w t t tw ψ − − = IMPROVED TRANSMITTER SPECTRAL PURITY STO-TR-SET-182 2 - 17 Figure 2-15...Washington, DC, USA, 11-15 May 2015. 42) P.S. Tan , J. Jakabosky, J.M. Stiles and S.D. Blunt, “On Higher-Order Representations of Polyphase- Coded FM Radar

  20. An S-band high gain relativistic klystron amplifier with high phase stability

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Science and Technology on High Power Microwave Laboratory, Mianyang 621900 (China); Li, Z. H.; Xu, Z.; Ma, Q. S. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Xie, H. Q. [College of Science, Southwestern University of Science and Technology, Mianyang 621010 (China)

    2014-11-15

    For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

  1. La escisión entre Ciencia Política y realidad política: el caso de la Seguridad Democrática

    Directory of Open Access Journals (Sweden)

    Carlos Andrés Ramírez González

    2014-12-01

    Full Text Available La política de seguridad democrática, adoptada por el Presidente Álvaro Uribe Vélez durante su periodo de gobierno, resultó en un viraje fundamental en los rumbos del país luego del fallido proceso de paz del gobierno Pastrana. En este sentido, el presente trabajo busca demostrar que la Ciencia Política abordó el fenómeno político en contravía con el curso de los hechos, de tal manera que mientras la política de Seguridad Democrática propugnaba por un aumento en la ofensiva militar, la visión desde la Ciencia Política se concentraba en la manera de llegar a unos diálogos de paz o una salida concertada al conflicto. Esto, por tanto, se puede traducir en un rechazo al punto de vista preponderante y a una postura alternativa en el estudio de la realidad política nacional. Para demostrar lo anterior, se realiza una revisión documental aplicada a artículos académicos en cuatro revistas de Ciencia Política del país: Análisis Político, Colombia Internacional, Papel Político y Estudios Políticos durante el periodo de publicación de 2002 a 2012.

  2. Space Radar Image of Manaus, Brazil

    Science.gov (United States)

    1999-01-01

    These two images were created using data from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). On the left is a false-color image of Manaus, Brazil acquired April 12, 1994, onboard space shuttle Endeavour. In the center of this image is the Solimoes River just west of Manaus before it combines with the Rio Negro to form the Amazon River. The scene is around 8 by 8 kilometers (5 by 5 miles) with north toward the top. The radar image was produced in L-band where red areas correspond to high backscatter at HH polarization, while green areas exhibit high backscatter at HV polarization. Blue areas show low backscatter at VV polarization. The image on the right is a classification map showing the extent of flooding beneath the forest canopy. The classification map was developed by SIR-C/X-SAR science team members at the University of California,Santa Barbara. The map uses the L-HH, L-HV, and L-VV images to classify the radar image into six categories: Red flooded forest Green unflooded tropical rain forest Blue open water, Amazon river Yellow unflooded fields, some floating grasses Gray flooded shrubs Black floating and flooded grasses Data like these help scientists evaluate flood damage on a global scale. Floods are highly episodic and much of the area inundated is often tree-covered. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those

  3. Structural parameter based modification of energy conscious ESPAR antenna system through optimization for WLAN’s dual-band operability

    CSIR Research Space (South Africa)

    Bembe, MJ

    2010-11-01

    Full Text Available single device. In this study the focus is on the modification of the antenna designs for dual-band functionality which is limited on the ESPAR antenna’s structural parameter. This modification should result in an antenna system which operates in both 2...

  4. Acesso de negros às universidades públicas

    Directory of Open Access Journals (Sweden)

    Guimarães Antonio Sérgio Alfredo

    2003-01-01

    Full Text Available Neste artigo, restringirei a análise do movimento por ações afirmativas ao sistema de educação superior do país, setor mais visado pelas demandas dos militantes e, por isso mesmo, responsável pelo caráter de classe média dessas ações. Como veremos, tais demandas encontraram respostas quase que imediatas do sistema político brasileiro, tanto por parte do governo quanto por parte dos políticos, ainda que continuem despertando fortes resistências da sociedade civil. Meu propósito é compreender os motivos de reações tão díspares. Antes, porém, farei uma rápida apresentação dos problemas educacionais do país e também das medidas que vêm sendo adotadas pelo governo e pelo sistema político, em geral, para enfrentá-los.

  5. Advanced Architectures for Modern Weather/Multifunction Radars

    Science.gov (United States)

    2017-03-01

    Radar (PAIR) system, a mobile , C-band, active phased array with multiple digital beams for imaging (under development). The digital transceiver... backend from Horus is also being used to drive row-based analog subarrays of the future Polarimetric Atmospheric Imaging Radar (PAIR, Fig. 6), which is

  6. Classification of Agricultural Crops in Radar Images

    NARCIS (Netherlands)

    Hoogeboom, P.

    1983-01-01

    For the past few years an accurate X-band SLAR system with digital recording has been available in The Netherlands. The images of this system are corrected to indicate radar backscatter coefficients (gamma) instead of arbitrary greytones. In 1980 a radar measurement campaign was organized in the

  7. Imprensa política e Separatismo no Sul de Minas Gerais, século XIX

    Directory of Open Access Journals (Sweden)

    Pérola Maria Goldfeder e Castro

    2010-07-01

    Full Text Available RESUMO:A cidade de Campanha afirmou-se durante o século XIX como importante localidade propagadora de idéias separatistas no Sul de Minas Gerais. Nela surgiram vários jornais e projetos parlamentares que tinham como aspiração comum a provincialização daquela região. Num primeiro momento, este texto identifica as transformações históricas no estatuto social e político da imprensa moderna. Em seguida, analisam-se os fatores de surgimento das idéias separatistas no Sul de Minas Gerais durante o século XIX, materializadas na imprensa local. Por fim, algumas considerações sobre o Movimento Separatista de 1892 e o posicionamento de setores da imprensa local quanto ao assunto.PALAVRAS-CHAVE: Imprensa; Separatismo; Sul de MinasABSTRACT: City Campaign was stated during the nineteenth century as important propagator town of separatist ideas in southern Minas Gerais. it there were several newspapers and parliamentary projects that had as common aspiration to provincializing that region. In a first Currently, this paper identifies the historical changes in status social and political development of modern press. Then we analyze the factors emergence of separatist ideas in the South of Minas Gerais during the nineteenth century, materialized in the local press. Finally, some considerations on the Separatist Movement of 1892 and the positioning sectors of the local media for that matter. KEYWORDS: Press, Separatism, southern Minas GeraisRecebido: 15/06/2010       Aceito: 14/07/2010

  8. Aborto inducido, séptico y shock séptico

    Directory of Open Access Journals (Sweden)

    Omar Sandoval Muñoz

    2016-07-01

    Full Text Available El aborto provocado séptico en Chile estuvo por varias décadas dentro de las primeras causas de mortalidad materna, y en 1960 la tasa de mortalidad materna por aborto era de 107/100.000 NV. El desarrollo y progreso en diversas áreas de nuestro país, sumado a las políticas sanitarias implementadas gubernamentalmente, han logrado disminuir la mortalidad materna por aborto de manera muy significativa, siendo ésta de 0.8/100.000 NV en 2005 y manteniéndose estable y por debajo de 1.5/100.000 NV desde el 2001 en adelante. En el presente artículo se revisa y compara el perfil epidemiológico de la mujer que actualmente se realiza un aborto y además se aborda el diagnóstico y tratamiento médico desde la perspectiva gineco-obstétrica.

  9. Aborto inducido, séptico y shock séptico

    Directory of Open Access Journals (Sweden)

    Omar Sandoval Muñoz

    2009-06-01

    Full Text Available El aborto provocado séptico en Chile estuvo por varias décadas dentro de las primeras causas de mortalidad materna, y en 1960 la tasa de mortalidad materna por aborto era de 107/100.000 NV. El desarrollo y progreso en diversas áreas de nuestro país, sumado a las políticas sanitarias implementadas gubernamentalmente, han logrado disminuir la mortalidad materna por aborto de manera muy significativa, siendo ésta de 0.8/100.000 NV en 2005 y manteniéndose estable y por debajo de 1.5/100.000 NV desde el 2001 en adelante. En el presente artículo se revisa y compara el perfil epidemiológico de la mujer que actualmente se realiza un aborto y además se aborda el diagnóstico y tratamiento médico desde la perspectiva gineco-obstétrica.

  10. Morgenthau: ¿el Maquiavelo de la política internacional?

    Directory of Open Access Journals (Sweden)

    Leonardo Carvajal H.

    2007-11-01

    Full Text Available Maquiavelo y Morgenthau respondieron con creces a la pregunta central: ¿en qué se diferencia la política internacional de las relaciones internacionales? Este interrogante fue considerado en las obras principales de los dos autores (El príncipe y Política entre las naciones, quienes establecen que los conceptos se diferencian en que el poder es el elemento esencial tanto en la política doméstica como en la “política internacional”; mientras que por “relaciones internacionales” se entiende todo el cúmulo de asuntos que tiene lugar en el escenario mundial, varios de los cuales no presentan ningún componente de “poder político” y, además, tales acciones se adelantan no sólo por parte del Estado sino también por una multiplicidad de actores que incluye individuos, iglesias, ONG, partidos, empresas. Es, pues, una interesante comparación entre el pensamiento de Nicolás Maquiavelo y el de Hans Morgenthau.

  11. Preliminary results from the U.S. participation in the 2000 Beam Park Experiment

    Science.gov (United States)

    Stansbery, Gene

    2001-10-01

    The United States participated in the 2000 Beam Park Experiment (BPE) conducted in late October, 2000 under the auspices of the Inter-Agency Space Debris Coordination Committee (IADC). The U.S. participated using several sensors which have participated in previous campaigns: Haystack, TRADEX, and COBRA DANE radars, and the Liquid Mirror Telescope. New to the BPE experiments this time are the GBR-P radar located at Kwajalein Atoll and the Haystack Auxiliary (HAX) radar located in Massachusetts. This paper will present and discuss preliminary results from each of the participating U.S. sensors.

  12. Ab Initio factorized LCAO calculations of the electronic band structure of ZnSe, ZnS, and the (ZnSe)1(ZnS)1 strained-layer superlattice

    International Nuclear Information System (INIS)

    Marshall, T.S.; Wilson, T.M.

    1992-01-01

    The authors report on the results of electronic band structure calculations of bulk ZnSe, bulk ZnS and the (ZnSe) 1 (ZnS) 1 , strained-layer superlattice (SLS) using the ab initio factorized linear combination of atomic orbitals method. The bulk calculations were done using the standard primitive nonrectangular 2-atom zinc blende unit cell, while the SLS calculation was done using a primitive tetragonal 4-atom unit cell modeled from the CuAu I structure. The analytic fit to the SLS crystalline potential was determined by using the nonlinear coefficients from the bulk fits. The CPU time saved by factorizing the energy matrix integrals and using a rectangular unit cell is discussed

  13. Estimation of High-Frequency Earth-Space Radio Wave Signals via Ground-Based Polarimetric Radar Observations

    Science.gov (United States)

    Bolen, Steve; Chandrasekar, V.

    2002-01-01

    Expanding human presence in space, and enabling the commercialization of this frontier, is part of the strategic goals for NASA's Human Exploration and Development of Space (HEDS) enterprise. Future near-Earth and planetary missions will support the use of high-frequency Earth-space communication systems. Additionally, increased commercial demand on low-frequency Earth-space links in the S- and C-band spectra have led to increased interest in the use of higher frequencies in regions like Ku and Ka-band. Attenuation of high-frequency signals, due to a precipitating medium, can be quite severe and can cause considerable disruptions in a communications link that traverses such a medium. Previously, ground radar measurements were made along the Earth-space path and compared to satellite beacon data that was transmitted to a ground station. In this paper, quantitative estimation of the attenuation along the propagation path is made via inter-comparisons of radar data taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and ground-based polarimetric radar observations. Theoretical relationships between the expected specific attenuation (k) of spaceborne measurements with ground-based measurements of reflectivity (Zh) and differential propagation phase shift (Kdp) are developed for various hydrometeors that could be present along the propagation path, which are used to estimate the two-way path-integrated attenuation (PIA) on the PR return echo. Resolution volume matching and alignment of the radar systems is performed, and a direct comparison of PR return echo with ground radar attenuation estimates is made directly on a beam-by-beam basis. The technique is validated using data collected from the TExas and Florida UNderflights (TEFLUN-B) experiment and the TRMM large Biosphere-Atmosphere experiment in Amazonia (LBA) campaign. Attenuation estimation derived from this method can be used for strategiC planning of communication systems for

  14. Arma del contrapoder: Humor político y medios

    OpenAIRE

    César Ulloa Tapia

    2008-01-01

    El humor político en los medios de comunicación tiene enorme acogida en las audiencias ya que logra lo que pueden editoriales, análisis académicos y demás espacios de opinión. Es la mejor manera de denunciar, advertir, sancionar e incluso develar lo que hace o deja de hacer el poder político. El humor político está considerado como contrapoder. El periodismo que usa el humor es eficaz, tanto en el mensaje como en su efecto, pues describe las situaciones y recurre a comparaciones y símiles....

  15. Observing the semiconducting band-gap alignment of MoS{sub 2} layers of different atomic thicknesses using a MoS{sub 2}/SiO{sub 2}/Si heterojunction tunnel diode

    Energy Technology Data Exchange (ETDEWEB)

    Nishiguchi, Katsuhiko, E-mail: nishiguchi.katsuhiko@lab.ntt.co.jp; Yamaguchi, Hiroshi; Fujiwara, Akira [NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198 (Japan); Castellanos-Gomez, Andres; Zant, Herre S. J. van der; Steele, Gary A. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands)

    2015-08-03

    We demonstrate a tunnel diode composed of a vertical MoS{sub 2}/SiO{sub 2}/Si heterostructure. A MoS{sub 2} flake consisting four areas of different thicknesses functions as a gate terminal of a silicon field-effect transistor. A thin gate oxide allows tunneling current to flow between the n-type MoS{sub 2} layers and p-type Si channel. The tunneling-current characteristics show multiple negative differential resistance features, which we interpret as an indication of different conduction-band alignments of the MoS{sub 2} layers of different thicknesses. The presented tunnel device can be also used as a hybrid-heterostructure device combining the advantages of two-dimensional materials with those of silicon transistors.

  16. Hydrometeor discrimination in melting layer using multiparameter airborne radar measurement

    Science.gov (United States)

    Kumagai, H.; Meneghini, R.; Kozu, T.

    1992-01-01

    Results from a multiparameter airborne radar/radiometer experiment (the Typhoon experiment) are presented. The experiment was conducted in the western Pacific with the NASA DC-8 aircraft, in which a dual-wavelength at X-band and Ka-band and dual-polarization at X-band radar was installed. The signatures of dBZ(X), dBZ(Ka), LDR (linear depolarization ratio) at X-band and DZ=dBZ(X)-dBZ(Ka) are discussed for the data obtained in the penetration of the typhoon Flo. With emphasis on discrimination of hydrometeor particles, some statistical features of the brightband in stratiform rain are discussed.

  17. David Rosenthal’s Tirant lo Blanc turns 30

    Directory of Open Access Journals (Sweden)

    Jan Reinhart

    2014-12-01

    Full Text Available The groundbreaking English language translation of Tirant lo Blanc by New York poet and academic David Rosenthal remains dominant three decades after its initial, and celebrated, release. Rosenthal’s controversially fluid and concise rendering of the Valencian classic survived a serious challenge 20 years ago by a more literal version from a well-meaning amateur translator and journeyman academic backed by a leading U.S.-based Catalan scholar. The article reviews the controversy and compares the two versions, adding comments from some of the key critics. La traducció capdavantera a l’anglés del Tirant lo Blanc, feta pel poeta i erudit de Nova York, David Rosenthal, continua mantenint la seua importància, tres dècades després de publicar-se. La polèmica versió dúctil i concisa de Rosenthal del clàssic valencià, ha sobreviscut el desafiament seriós, de fa vint anys, de la versió més literal d’un benintencionat traductor amateur i acadèmci oficial, recolzat per un destacat erudit català establert als Estats Units. L’article revisa la polèmica i compara les dues versions, tot afegint els comentaris d’alguns dels crítics més importants.

  18. Suitability of GaN and LDMOS for 70–82% efficiency 120–200W HPA addressing spaceborne P-band radar applications

    DEFF Research Database (Denmark)

    Le Gallou, N.; Vidkjær, Jens; Poivey, C.

    2012-01-01

    This paper addresses the development of P-band (435 MHz) HPA based on different technologies (GaN HEMT, LDMOS FET) for future use in pace radar applications in the context of the Biomass project. In particular best in class PAE of 70%–82% is targeted and achieved for power levels of 120W. In order...

  19. Semiconductor band alignment from first principles: a new nonequilibrium Green's function method applied to the CZTSe/CdS interface for photovoltaics

    DEFF Research Database (Denmark)

    Palsgaard, Mattias Lau Nøhr; Crovetto, Andrea; Gunst, Tue

    2016-01-01

    In this paper we present a method to obtain the band offset of semiconductor heterointerfaces from Density Functional Theory together with the nonequilibrium Green's function method. Band alignment and detailed properties of the interface between Cu2ZnSnSe4 and CdS are extracted directly from first...... principles simulations. The interface is important for photovoltaics applications where in particular the band offsets are important for efficiency. The band bending pose a problem for accurate atomistic simulations of band offsets due to its long range. Here we investigate two different methods for dealing...... with band bending directly. One involves doping the materials to induce a shorter screening length. The other method is to apply a voltage bias across the interface to correct for the band bending. The calculated band offsets agree well with previous experimental and theoretical studies and, interestingly...

  20. Políticas del Estado en Relación con los Estudiantes

    Directory of Open Access Journals (Sweden)

    Hugo Casanova Cardiel

    1999-01-01

    Full Text Available Las políticas educativas implementadas en México a partir de los años setenta, se han caracterizado por la poca preocupación e interés por parte del Estado en la educación. Es evidente el atraso del país en este sentido y las carencias por las que atraviesa el sistema educativo nacional, debido a políticas gubernamentales que responden únicamente a intereses particulares de cada gobierno y no dan solución a las verdaderas demandas sociales, ocasionando con ello, políticas educativas poco homogéneas y como sucede frecuentemente en México sin continuidad es decir que se abandonan al finalizar cada sexenio para implementar nuevas políticas que no progresan. Es necesario establecer políticas adecuadas al sistema mexicano, que den respuesta a las demandas de la creciente y más demandante población en el país, que se rediseñen planes y programas educativos y sobre todo que exista la planeación y seguimiento de estos.

  1. La inestabilidad política de los reyes visigodos de Toledo (s. VI-VIII: balance historiográfico y nueva propuesta de análisis

    Directory of Open Access Journals (Sweden)

    Sabrina Soledad Orlowski

    2012-03-01

    Full Text Available La inestabilidad política regia visigoda es un fenómeno tan constante en la documentación de los siglos VI-VIII que motiva una investigación para dar cuenta de sus principios estructurales. Se propone que la evolución política de la realeza visigoda corresponde a lógicas de funcionamiento de las aristocracias en sociedades de dominación incompleta, que expresan una dinámica general de la temprana Edad Media. Las opiniones de los autores sobre este fenómeno son tan variadas que se vuelve imperioso realizar un balance del estado de la investigación, detectar los problemas existentes y, lo más importante, delinear una línea de trabajo a seguir

  2. Monitoring Strategies of Earth Dams by Ground-Based Radar Interferometry: How to Extract Useful Information for Seismic Risk Assessment.

    Science.gov (United States)

    Di Pasquale, Andrea; Nico, Giovanni; Pitullo, Alfredo; Prezioso, Giuseppina

    2018-01-16

    The aim of this paper is to describe how ground-based radar interferometry can provide displacement measurements of earth dam surfaces and of vibration frequencies of its main concrete infrastructures. In many cases, dams were built many decades ago and, at that time, were not equipped with in situ sensors embedded in the structure when they were built. Earth dams have scattering properties similar to landslides for which the Ground-Based Synthetic Aperture Radar (GBSAR) technique has been so far extensively applied to study ground displacements. In this work, SAR and Real Aperture Radar (RAR) configurations are used for the measurement of earth dam surface displacements and vibration frequencies of concrete structures, respectively. A methodology for the acquisition of SAR data and the rendering of results is described. The geometrical correction factor, needed to transform the Line-of-Sight (LoS) displacement measurements of GBSAR into an estimate of the horizontal displacement vector of the dam surface, is derived. Furthermore, a methodology for the acquisition of RAR data and the representation of displacement temporal profiles and vibration frequency spectra of dam concrete structures is presented. For this study a Ku-band ground-based radar, equipped with horn antennas having different radiation patterns, has been used. Four case studies, using different radar acquisition strategies specifically developed for the monitoring of earth dams, are examined. The results of this work show the information that a Ku-band ground-based radar can provide to structural engineers for a non-destructive seismic assessment of earth dams.

  3. Por uma Economia Política do Funk Carioca: notas sobre a teoria pós-moderna e seus desdobramentos na música popular contemporânea

    Directory of Open Access Journals (Sweden)

    Pablo Cezar Laignier

    2011-07-01

    Full Text Available

    O objetivo deste trabalho é analisar as relações entre o funk carioca enquanto gênero musical e a teoria sobre as condições de uma economia política moderna no estágio contemporâneo, em que a acumulação flexível e os rápidos giros nos ciclos do capital se desdobram em uma sociabilidade e em aspectos culturais de mobilidade, risco, incerteza, crise, fluidez, portabilidade e interconexão. O referencial teórico é baseado principalmente nas obras de Harvey (2006, Lyotard (2003 e Anderson (1999. A primeira seção discute, com base nestes autores, a conjuntura pós-moderna; a segunda apresenta alguns exemplos dos desdobramentos das características classificadas como pós-modernas na música massiva/popular; a terceira discute algumas características do funk carioca como gênero musical e como cena cultural, inserindo-o no contexto político-econômico do Rio de Janeiro contemporâneo.

  4. Performance of horn-coupled transition edge sensors for L- and S-band optical detection on the SAFARI instrument

    Science.gov (United States)

    Goldie, D. J.; Glowacka, D. M.; Withington, S.; Chen, Jiajun; Ade, P. A. R.; Morozov, D.; Sudiwala, R.; Trappe, N. A.; Quaranta, O.

    2016-07-01

    We describe the geometry, architecture, dark- and optical performance of ultra-low-noise transition edge sensors as THz detectors for the SAFARI instrument. The TESs are fabricated from superconducting Mo/Au bilayers coupled to impedance-matched superconducting β-phase Ta thin-film absorbers. The detectors have phonon-limited dark noise equivalent powers of order 0.5 - 1.0 aW/ √ Hz and saturation powers of order 20 - 40 fW. The low temperature test configuration incorporating micro-machined backshorts is also described, and construction and typical performance characteristics for the optical load are shown. We report preliminary measurements of the optical performance of these TESs for two SAFARI bands; L-band at 110 - 210 μm and S-band 34 - 60 μm .

  5. Space Radar Image of Central Sumatra, Indonesia

    Science.gov (United States)

    1994-01-01

    This is a radar image of the central part of the island of Sumatra in Indonesia that shows how the tropical rainforest typical of this country is being impacted by human activity. Native forest appears in green in this image, while prominent pink areas represent places where the native forest has been cleared. The large rectangular areas have been cleared for palm oil plantations. The bright pink zones are areas that have been cleared since 1989, while the dark pink zones are areas that were cleared before 1989. These radar data were processed as part of an effort to assist oil and gas companies working in the area to assess the environmental impact of both their drilling operations and the activities of the local population. Radar images are useful in these areas because heavy cloud cover and the persistent smoke and haze associated with deforestation have prevented usable visible-light imagery from being acquired since 1989. The dark shapes in the upper right (northeast) corner of the image are a chain of lakes in flat coastal marshes. This image was acquired in October 1994 by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. Environmental changes can be easily documented by comparing this image with visible-light data that were acquired in previous years by the Landsat satellite. The image is centered at 0.9 degrees north latitude and 101.3 degrees east longitude. The area shown is 50 kilometers by 100 kilometers (31 miles by 62 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is L-band vertically transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  6. Detecting weather radar clutter using satellite-based nowcasting products

    DEFF Research Database (Denmark)

    Jensen, Thomas B.S.; Gill, Rashpal S.; Overgaard, Søren

    2006-01-01

    This contribution presents the initial results from experiments with detection of weather radar clutter by information fusion with satellite based nowcasting products. Previous studies using information fusion of weather radar data and first generation Meteosat imagery have shown promising results...... for the detecting and removal of clutter. Naturally, the improved spatio-temporal resolution of the Meteosat Second Generation sensors, coupled with its increased number of spectral bands, is expected to yield even better detection accuracies. Weather radar data from three C-band Doppler weather radars...... Application Facility' of EUMETSAT and is based on multispectral images from the SEVIRI sensor of the Meteosat-8 platform. Of special interest is the 'Precipitating Clouds' product, which uses the spectral information coupled with surface temperatures from Numerical Weather Predictions to assign probabilities...

  7. Direct band gap measurement of Cu(In,Ga)(Se,S)2 thin films using high-resolution reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Heo, Sung; Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su; Song, Taewon; Lee, Dongho; Nam, Junggyu; Kang, Hee Jae; Choi, Pyung-Ho; Choi, Byoung-Deog

    2015-01-01

    To investigate the band gap profile of Cu(In 1−x ,Ga x )(Se 1−y S y ) 2 of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth

  8. Relating P-band AIRSAR backscatter to forest stand parameters

    Science.gov (United States)

    Wang, Yong; Melack, John M.; Davis, Frank W.; Kasischke, Eric S.; Christensen, Norman L., Jr.

    1993-01-01

    As part of research on forest ecosystems, the Jet Propulsion Laboratory (JPL) and collaborating research teams have conducted multi-season airborne synthetic aperture radar (AIRSAR) experiments in three forest ecosystems including temperate pine forest (Duke, Forest, North Carolina), boreal forest (Bonanza Creek Experimental Forest, Alaska), and northern mixed hardwood-conifer forest (Michigan Biological Station, Michigan). The major research goals were to improve understanding of the relationships between radar backscatter and phenological variables (e.g. stand density, tree size, etc.), to improve radar backscatter models of tree canopy properties, and to develop a radar-based scheme for monitoring forest phenological changes. In September 1989, AIRSAR backscatter data were acquired over the Duke Forest. As the aboveground biomass of the loblolly pine forest stands at Duke Forest increased, the SAR backscatter at C-, L-, and P-bands increased and saturated at different biomass levels for the C-band, L-band, and P-band data. We only use the P-band backscatter data and ground measurements here to study the relationships between the backscatter and stand density, the backscatter and mean trunk dbh (diameter at breast height) of trees in the stands, and the backscatter and stand basal area.

  9. A procedure to correct the effects of a relative delay between the quadrature components of radar signals at base band

    Directory of Open Access Journals (Sweden)

    Grydeland

    2005-01-01

    Full Text Available The real and imaginary parts of baseband signals are obtained from a real narrow-band signal by quadrature mixing, i.e. by mixing with cosine and sine signals at the narrow band's selected center frequency. We address the consequences of a delay between the outputs of the quadrature mixer, which arise when digital samples of the quadrature baseband signals are not synchronised, i.e. when the real and imaginary components have been shifted by one or more samples with respect to each other. Through analytical considerations and simulations of such an error on different synthetic signals, we show how this error can be expected to afflict different measurements. In addition, we show the effect of the error on actual incoherent scatter radar data obtained by two different digital receiver systems used in parallel at the EISCAT Svalbard Radar (ESR. The analytical considerations indicate a procedure to correct the error, albeit with some limitations due to a small singular region. We demonstrate the correction procedure on actually afflicted data and compare the results to simultaneously acquired unafflicted data. We also discuss the possible data analysis strategies, including some that avoid dealing directly with the singular region mentioned above.

  10. A síntese imperfeita: articulação entre política externa e política de defesa na era Cardoso

    Directory of Open Access Journals (Sweden)

    João Paulo Soares Alsina Jr.

    2003-12-01

    Full Text Available Esse artigo tem por objetivo gerar hipóteses sobre a articulação entre política externa e política de defesa na gestão Cardoso. Partiu-se de estudo de caso sobre a formulação da Política de Defesa Nacional (PDN e as conseqüências dessa para a institucionalização do Ministério da Defesa (MD. Constatou-se a baixa prioridade atribuída pela diplomacia ao poder militar como ferramenta de política externa. Finalmente, explicitou-se a inexistência de mecanismos efetivos de articulação.This article has the objective of producing hypotheses on the articulation between foreign and defense policies during President's Cardoso administration. Initially, a case study on the formulation of the National Defense Policy Document (PDN and its consequences to the institutionalization of the Defense Ministry (MD was conducted. The low priority Brazilian diplomacy attributes to military power as a foreign policy tool was established. Finally, the lack of effective articulation mechanisms between foreign and defense policies was stressed.

  11. Quasiparticle self-consistent GW calculations for PbS, PbSe, and PbTe: Band structure and pressure coefficients

    DEFF Research Database (Denmark)

    Svane, Axel; Christensen, Niels Egede; Cardona,, M.

    2010-01-01

    The electronic band structures of PbS, PbSe, and PbTe in the rocksalt structure are calculated with the quasiparticle self-consistent GW (QSGW) approach with spin-orbit coupling included. The semiconducting gaps and their deformation potentials as well as the effective masses are obtained. The GW...

  12. 16O + 16O + valence neutrons in molecular orbitals structures of positive- and negative-parity superdeformed bands in 34S

    International Nuclear Information System (INIS)

    Taniguchi, Yasutaka

    2015-01-01

    The structures of superdeformed (SD) states in 34 S have been investigated using the antisymmetrized molecular dynamics and generator coordinate method (GCM). The GCM basis wave functions are calculated via energy variation with a constraint on the quadrupole deformation parameter β. By applying the GCM after parity and angular momentum projections, the coexistence of two positive- and one negative-parity SD bands are predicted, and low-lying states and other deformed bands are obtained. The SD bands have structures of 16 O + 16 O + two valence neutrons in molecular orbitals around the two 16 O cores in a cluster picture. The configurations of the two valence neutrons are δ 2 and π 2 for the positive-parity SD bands and π 1 δ 1 for the negative-parity SD band. (author)

  13. 16O + 16O + valence neutrons in molecular orbitals structures of positive- and negative-parity superdeformed bands in 34S

    International Nuclear Information System (INIS)

    Taniguchi, Yasutaka

    2014-01-01

    The structures of superdeformed (SD) states in 34 S are investigated using the antisymmetrized molecular dynamics and generator coordinate method (GCM). The GCM basis wave functions are calculated via energy variation with a constraint on the quadrupole deformation parameter β. By applying the GCM after parity and angular momentum projections, the coexistence of two positive- and one negative-parity SD bands are predicted, and low-lying states and other deformed bands are obtained. The SD bands have structures of 16 O + 16 O + two valence neutrons in molecular orbitals around the two 16 O cores in a cluster picture. The configurations of the two valence neutrons are δ 2 and π 2 for the positive-parity SD bands and π 1 δ 1 for the negative-parity SD band

  14. Finite-size effects on band structure of CdS nanocrystallites studied by positron annihilation

    International Nuclear Information System (INIS)

    Kar, Soumitra; Biswas, Subhajit; Chaudhuri, Subhadra; Nambissan, P.M.G.

    2005-01-01

    Quantum confinement effects in nanocrystalline CdS were studied using positrons as spectroscopic probes to explore the defect characteristics. The lifetime of positrons annihilating at the vacancy clusters on nanocrystalline grain surfaces increased remarkably consequent to the onset of such finite-size effects. The Doppler broadened line shape was also found to reflect rather sensitively such distinct changes in the electron momentum redistribution scanned by the positrons, owing to the widening of the band gap. The nanocrystalline sizes of the samples used were confirmed from x-ray diffraction and high resolution transmission electron microscopy and the optical absorption results supported the quantum size effects. Positron annihilation results indicated distinct qualitative changes between CdS nanorods and the bulk sample, notwithstanding the identical x-ray diffraction pattern and close resemblance of the optical absorption spectra. The results are promising in the event of positron annihilation being proved to be a very successful tool for the study of such finite-size effects in semiconductor nanoparticles

  15. Space Radar Image of Harvard Forest

    Science.gov (United States)

    1999-01-01

    This is a radar image of the area surrounding the Harvard Forest in north-central Massachusetts that has been operated as a ecological research facility by Harvard University since 1907. At the center of the image is the Quabbin Reservoir, and the Connecticut River is at the lower left of the image. The Harvard Forest itself is just above the reservoir. Researchers are comparing the naturally occurring physical disturbances in the forest and the recent and projected chemical disturbances and their effects on the forest ecosystem. Agricultural land appears dark blue/purple, along with low shrub vegetation and some wetlands. Urban development is bright pink; the yellow to green tints are conifer-dominated vegetation with the pitch pine sand plain at the middle left edge of the image appearing very distinctive. The green tint may indicate pure pine plantation stands, and deciduous broadleaf trees appear gray/pink with perhaps wetter sites being pinker. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth. The image is centered at 42.50 degrees North latitude and 72.33 degrees West longitude and covers an area of 53 kilometers 63 by kilometers (33 miles by 39 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted and horizontally received; green is L-band horizontally transmitted and vertically received; and blue is C-band horizontally transmitted and horizontally received.

  16. Space Radar Image of Sydney, Australia

    Science.gov (United States)

    1994-01-01

    This spaceborne radar image is dominated by the metropolitan area of Australia's largest city, Sydney. Sydney Harbour, with numerous coves and inlets, is seen in the upper center of the image, and the roughly circular Botany Bay is shown in the lower right. The downtown business district of Sydney appears as a bright white area just above the center of the image. The Sydney Harbour Bridge is a white line adjacent to the downtown district. The well-known Sydney Opera House is the small, white dot to the right of the bridge. Urban areas appear yellow, blue and brown. The purple areas are undeveloped areas and park lands. Manly, the famous surfing beach, is shown in yellow at the top center of the image. Runways from the Sydney Airport are the dark features that extend into Botany Bay in the lower right. Botany Bay is the site where Captain James Cook first landed his ship, Endeavour, in 1770. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 20, 1994, onboard the space shuttle Endeavour. The area shown is 33 kilometers by 38kilometers (20 miles by 23 miles) and is centered at 33.9 degrees south latitude, 151.2 degrees east longitude. North is toward the upper left. The colors are assigned to different radar frequenciesand polarizations as follows: red is L-band, vertically transmittedand horizontally received; green is C-band, vertically transmitted and horizontally received; and blue is C-band, vertically transmittedand received. SIR-C/X-SAR, a joint mission of the German, Italianand United States space agencies, is part of NASA's Mission to Planet Earth. #####

  17. Charge separation dynamics in a narrow band gap polymer-PbS nanocrystal blend for efficient hybrid solar cells

    OpenAIRE

    Piliego, Claudia; Manca, Marianna; Kroon, Renee; Yarema, Maksym; Szendrei, Krisztina; Andersson, Mats R.; Heiss, Wolfgang; Loi, Maria A.

    2012-01-01

    We have demonstrated efficient hybrid solar cells based on lead sulfide (PbS) nanocrystals and a narrow band gap polymer, poly[{2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl}-alt-{[2,2'-(1,4-phenylene)bis-thiophene]-5,5'-diyl}], (PDPPTPT). An opportune mixing of the two materials led to the formation of an energetically favorable bulk hetero-junction with a broad spectral response. Using a basic device structure, we reached a power conversion efficiency of s...

  18. Simultaneous observations of ESF irregularities over Indian region using radar and GPS

    Directory of Open Access Journals (Sweden)

    S. Sripathi

    2008-10-01

    Full Text Available In this paper, we present simultaneous observations of temporal and spatial variability of total electron content (TEC and GPS amplitude scintillations on L1 frequency (1.575 GHz during the time of equatorial spread F (ESF while the MST radar (53 MHz located at Gadanki (13.5° N, 79.2° E, Dip latitude 6.3° N, a low latitude station, made simultaneous observations. In particular, the latitudinal and longitudinal extent of TEC and L-band scintillations was studied in the Indian region for different types of ESF structures observed using the MST radar during the low solar activity period of 2004 and 2005. Simultaneous radar and GPS observations during severe ESF events in the pre-midnight hour reveal that significant GPS L band scintillations, depletions in TEC, and the double derivative of the TEC index (DROTI, which is a measure of fluctuations in TEC, obtained at low latitudes coincide with the appearance of radar echoes at Gadanki. As expected, when the irregularities reach higher altitudes as seen in the radar map during pre-midnight periods, strong scintillations on an L-band signal are observed at higher latitudes. Conversely, when radar echoes are confined to only lower altitudes, weak scintillations are found and their latitudinal extent is small. During magnetically quiet periods, we have recorded plume type radar echoes during a post-midnight period that is devoid of L-band scintillations. Using spectral slopes and cross-correlation index of the VHF scintillation observations, we suggest that these irregularities could be "dead" or "fossil" bubbles which are just drifting in from west. This scenario is consistent with the observations where suppression of pre-reversal enhancement (PRE in the eastward electric field is indicated by ionosonde observations of the height of equatorial F layer and also occurrence of low spectral width in the radar observations relative to pre-midnight period. However, absence of L-band scintillations during

  19. Space Radar Image of Bahia

    Science.gov (United States)

    1994-01-01

    This is a color composite image of southern Bahia, Brazil, centered at 15.22 degree south latitude and 39.07 degrees west longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on its 38th orbit of Earth on October 2, 1994. The image covers an area centered over the Una Biological Reserve, one the largest protected areas in northeastern Brazil. The 7,000-hectare reserve is administered by the Brazilian Institute for the Environment and is part of the larger Atlantic coastal forest, a narrow band of rain forest extending along the eastern coast of Brazil. The Atlantic coastal forest of southern Bahia is one of the world's most threatened and diverse ecosystems. Due to widespread settlement, only 2 to 5 percent of the original forest cover remains. Yet the region still contains an astounding variety of plants and animals, including a large number of endemic species. More than half of the region's tree species and 80 percent of its animal species are indigenous and found nowhere else on Earth. The Una Reserve is also the only federally protected habitat for the golden-headed lion tamarin, the yellow-breasted capuchin monkey and many other endangered species. In the past few years, scientists from Brazilian and international conservation organizations have coordinated efforts to study the biological diversity of this region and to develop practical and economically viable options for preserving the remaining primary forests in southern Bahia. The shuttle imaging radar is used in this study to identify various land uses and vegetation types, including remaining patches of primary forest, cabruca forest (cacao planted in the understory of the native forest), secondary forest, pasture and coastal mangrove. Standard remote-sensing technology that relies on light reflected from the forest canopy cannot accurately distinguish between cabruca and undisturbed forest. Optical remote sensing is also

  20. Airborne polarimetric Doppler weather radar: trade-offs between various engineering specifications

    Science.gov (United States)

    Vivekanandan, Jothiram; Loew, Eric

    2018-01-01

    NCAR EOL is investigating potential configurations for the next-generation airborne phased array radar (APAR) that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. The APAR will operate at C band. The APAR will use the electronic scanning (e-scan) feature to acquire the optimal number of independent samples for recording research-quality measurements. Since the airborne radar has only a limited time for collecting measurements over a specified region (moving aircraft platform ˜ 100 m s-1), beam multiplexing will significantly enhance its ability to collect high-resolution, research-quality measurements. Beam multiplexing reduces errors in radar measurements while providing rapid updates of scan volumes. Beamwidth depends on the size of the antenna aperture. Beamwidth and directivity of elliptical, circular, and rectangular antenna apertures are compared and radar sensitivity is evaluated for various polarimetric configurations and transmit-receive (T/R) elements. In the case of polarimetric measurements, alternate transmit with alternate receive (single-channel receiver) and simultaneous reception (dual-channel receiver) is compared. From an overall architecture perspective, element-level digitization of T/R module versus digital sub-array is considered with regard to flexibility in adaptive beamforming, polarimetric performance, calibration, and data quality. Methodologies for calibration of the radar and removing bias in polarimetric measurements are outlined. The above-mentioned engineering options are evaluated for realizing an optimal APAR system suitable for measuring the high temporal and spatial resolutions of Doppler and polarimetric measurements of precipitation and clouds.