WorldWideScience

Sample records for array feed calibration

  1. Calibration of a photomultiplier array spectrometer

    Science.gov (United States)

    Bailey, Steven A.; Wright, C. Wayne; Piazza, Charles R.

    1989-01-01

    A systematic approach to the calibration of a photomultiplier array spectrometer is presented. Through this approach, incident light radiance derivation is made by recognizing and tracing gain characteristics for each photomultiplier tube.

  2. Coplanar waveguide feeds for phased array antennas

    Science.gov (United States)

    Simons, Rainee N.; Lee, Richard Q.

    1992-08-01

    The design and performance of the following coplanar waveguide (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and printed dipole arrays is presented: (1) CPW/microstrip line feed; (2) CPW/balanced stripline feed; (3) CPW/slotline feed; (4) grounded CPW (GCPW)/balanced coplanar stripline feed; and (5) CPW/slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  3. Calibration of the Cherenkov Telescope Array

    CERN Document Server

    Gaug, Markus; Berge, David; Reyes, Raquel de los; Doro, Michele; Foerster, Andreas; Maccarone, Maria Concetta; Parsons, Dan; van Eldik, Christopher

    2015-01-01

    The construction of the Cherenkov Telescope Array is expected to start soon. We will present the baseline methods and their extensions currently foreseen to calibrate the observatory. These are bound to achieve the strong requirements on allowed systematic uncertainties for the reconstructed gamma-ray energy and flux scales, as well as on the pointing resolution, and on the overall duty cycle of the observatory. Onsite calibration activities are designed to include a robust and efficient calibration of the telescope cameras, and various methods and instruments to achieve calibration of the overall optical throughput of each telescope, leading to both inter-telescope calibration and an absolute calibration of the entire observatory. One important aspect of the onsite calibration is a correct understanding of the atmosphere above the telescopes, which constitutes the calorimeter of this detection technique. It is planned to be constantly monitored with state-of-the-art instruments to obtain a full molecular and...

  4. Characterization of tapered slot antenna feeds and feed arrays

    Science.gov (United States)

    Kim, Young-Sik; Yngvesson, K. Sigfrid

    1990-01-01

    A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements.

  5. Parallel Calibration for Sensor Array Radio Interferometers

    CERN Document Server

    Brossard, Martin; Pesavento, Marius; Boyer, Rémy; Larzabal, Pascal; Wijnholds, Stefan J

    2016-01-01

    In order to meet the theoretically achievable imaging performance, calibration of modern radio interferometers is a mandatory challenge, especially at low frequencies. In this perspective, we propose a novel parallel iterative multi-wavelength calibration algorithm. The proposed algorithm estimates the apparent directions of the calibration sources, the directional and undirectional complex gains of the array elements and their noise powers, with a reasonable computational complexity. Furthermore, the algorithm takes into account the specific variation of the aforementioned parameter values across wavelength. Realistic numerical simulations reveal that the proposed scheme outperforms the mono-wavelength calibration scheme and approaches the derived constrained Cram\\'er-Rao bound even with the presence of non-calibration sources at unknown directions, in a computationally efficient manner.

  6. Measured Aperture-Array Noise Temperature of the Mark II Phased Array Feed for ASKAP

    CERN Document Server

    Chippendale, A P; Beresford, R J; Hampson, G A; Shaw, R D; Hayman, D B; Macleod, A; Forsyth, A R; Hay, S G; Leach, M; Cantrall, C; Brothers, M L; Hotan, A W

    2015-01-01

    We have measured the aperture-array noise temperature of the first Mk. II phased array feed that CSIRO has built for the Australian Square Kilometre Array Pathfinder telescope. As an aperture array, the Mk. II phased array feed achieves a beam equivalent noise temperature less than 40 K from 0.78 GHz to 1.7 GHz and less than 50 K from 0.7 GHz to 1.8 GHz for a boresight beam directed at the zenith. We believe these are the lowest reported noise temperatures over these frequency ranges for ambient-temperature phased arrays. The measured noise temperature includes receiver electronics noise, ohmic losses in the array, and stray radiation from sidelobes illuminating the sky and ground away from the desired field of view. This phased array feed was designed for the Australian Square Kilometre Array Pathfinder to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array.

  7. The Detector Calibration System for the CUORE cryogenic bolometer array

    CERN Document Server

    Cushman, J S; Davis, C J; Ejzak, L; Lenz, D; Lim, K E; Heeger, K M; Maruyama, R H; Nucciotti, A; Sangiorgio, S; Wise, T

    2016-01-01

    The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic experiment designed to search for neutrinoless double-beta decay of $^{130}$Te and other rare events. The CUORE detector consists of 988 TeO$_2$ bolometers operated underground at 10~mK in a dilution refrigerator at the Laboratori Nazionali del Gran Sasso. Candidate events are identified through a precise measurement of their energy. The absolute energy response of the detectors is established by the regular calibration of each individual bolometer using gamma sources. The close-packed configuration of the CUORE bolometer array combined with the extensive shielding surrounding the detectors requires the placement of calibration sources within the array itself. The CUORE Detector Calibration System is designed to insert radioactive sources into and remove them from the cryostat while respecting the stringent heat load, radiopurity, and operational requirements of the experiment. This paper describes the design, commissioning...

  8. An MLC calibration method using a detector array

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray [Department of Nuclear and Radiological Engineering, University of Florida, 202 Nuclear Science Building, Gainesville, Florida 32611-8300 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States) and Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States); Department of Radiation Oncology, Tulane University, 1415 Tulane Ave, HC65, New Orleans, Louisiana 70112 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States)

    2009-10-15

    Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 {+-}0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of {+-}0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

  9. MIMO Communication Using Single Feed Antenna Arrays

    DEFF Research Database (Denmark)

    Alrabadi, Osama

    Multi-input-multi-output (MIMO) communication has emerged as a promis- ing technology for meeting the increasing demand on higher data rates. The technology exploits the spatial resource dimension by sending the datas- treams to different locations in the multi element array (MEA) domain while...

  10. Stability of array spectroradiometers and their suitability for absolute calibrations

    Science.gov (United States)

    Nevas, Saulius; Teuber, Annette; Sperling, Armin; Lindemann, Matthias

    2012-04-01

    An investigation of the short- and long-term stability of various low-end and high-end array spectroradiometers is presented. Potentially weak points of array spectroradiometers with respect to their suitability for absolute calibrations are pointed out. The influence of ambient conditions on relevant instrumental characteristics and their temporal stability is discussed. It is shown that the temporal stability of some instruments can be significantly affected by high ambient humidity. Most important ambient temperature effects on instrument properties are also discussed.

  11. Calibrating camera and projector arrays for immersive 3D display

    Science.gov (United States)

    Baker, Harlyn; Li, Zeyu; Papadas, Constantin

    2009-02-01

    Advances in building high-performance camera arrays [1, 12] have opened the opportunity - and challenge - of using these devices for autostereoscopic display of live 3D content. Appropriate autostereo display requires calibration of these camera elements and those of the display facility for accurate placement (and perhaps resampling) of the acquired video stream. We present progress in exploiting a new approach to this calibration that capitalizes on high quality homographies between pairs of imagers to develop a global optimal solution delivering epipoles and fundamental matrices simultaneously for the entire system [2]. Adjustment of the determined camera models to deliver minimal vertical misalignment in an epipolar sense is used to permit ganged rectification of the separate streams for transitive positioning in the visual field. Individual homographies [6] are obtained for a projector array that presents the video on a holographically-diffused retroreflective surface for participant autostereo viewing. The camera model adjustment means vertical epipolar disparities of the captured signal are minimized, and the projector calibration means the display will retain these alignments despite projector pose variations. The projector calibration also permits arbitrary alignment shifts to accommodate focus-of-attention vengeance, should that information be available.

  12. Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

    Science.gov (United States)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2011-01-01

    This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.

  13. Advanced statistical tools for SNP arrays : signal calibration, copy number estimation and single array genotyping

    NARCIS (Netherlands)

    Rippe, Ralph Christian Alexander

    2012-01-01

    Fluorescence bias in in signals from individual SNP arrays can be calibrated using linear models. Given the data, the system of equations is very large, so a specialized symbolic algorithm was developed. These models are also used to illustrate that genomic waves do not exist, but are merely an arti

  14. Real-Time Calibration of the Murchison Widefield Array

    CERN Document Server

    Mitchell, D A; Wayth, R B; Sault, R J; Lonsdale, C J; Cappallo, R J; Morales, M F; Ord, S M

    2008-01-01

    The interferometric technique known as peeling addresses many of the challenges faced when observing with low-frequency radio arrays, and is a promising tool for the associated calibration systems. We investigate a real-time peeling implementation for next-generation radio interferometers such as the Murchison Widefield Array (MWA). The MWA is being built in Australia and will observe the radio sky between 80 and 300 MHz. The data rate produced by the correlator is just over 19 GB/s (a few Peta-Bytes/day). It is impractical to store data generated at this rate, and software is currently being developed to calibrate and form images in real time. The software will run on-site on a high-throughput real-time computing cluster at several tera-flops, and a complete cycle of calibration and imaging will be completed every 8 seconds. Various properties of the implementation are investigated using simulated data. The algorithm is seen to work in the presence of strong galactic emission and with realistic ionospheric c...

  15. Applications of trimode waveguide feeds in adaptive virtual array antennas

    Science.gov (United States)

    Allahgholi Pour, Z.; Shafai, Lotfollah

    2015-03-01

    This paper presents the formation of an adaptive virtual array antenna in a symmetric parabolic reflector antenna illuminated by trimode circular waveguide feeds with different mode alignments. The modes of interest are the TE11, TE21, and TM01 type modes. The terms TE and TM stand for the transverse electric and transverse magnetic modes, respectively. By appropriately exciting these modes and varying the mode orientations inside the primary feed, the effective source of radiation is displaced on the reflector aperture, while the resulting secondary patterns remain axial. Different antenna parameters such as gain, cross polarization, and phase center locations are investigated. It is demonstrated that the extra third mode facilitates the formation of symmetric virtual array antennas with reasonable cross polarization discriminations at the diagonal plane.

  16. Design of Multilevel Sequential Rotation Feeding Networks Used for Circularly Polarized Microstrip Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Aixin Chen

    2012-01-01

    Full Text Available Sequential rotation feeding networks can significantly improve performance of the circularly polarized microstrip antenna array. In this paper, single, double, and multiple series-parallel sequential rotation feeding networks are examined. Compared with conventional parallel feeding structures, these multilevel feeding techniques present reduction of loss, increase of bandwidth, and improvement of radiation pattern and polarization purity. By using corner-truncated square patch as the array element and adopting appropriate level of sequential rotation series-parallel feeding structures as feeding networks, microstrip arrays can generate excellent circular polarization (CP over a relatively wide frequency band. They can find wide applications in phased array radar and satellite communication systems.

  17. In-situ comparison calibration of infrasound array elements

    Science.gov (United States)

    Gabrielson, T. B.

    2009-12-01

    A typical infrasound array element consists of an infrasonic sensor connected to a multiple-pipe or porous-hose system for reduction of wind noise. While the frequency response of the sensor itself may be known, the wind-noise reduction system can modify that response. One approach to measuring the actual frequency response in situ is to perform a comparison calibration using ambient noise. The reference sensor must have a sufficiently low self noise and have a well characterized frequency response over the band of interest. In the cases presented here, three reference sensors are placed and summed to form a virtual reference at the geometric center of the pipe system. Under low-wind conditions, coherence between the virtual reference and the infrasound element is typically greater than 0.8 from 0.01 to 8 Hz. Proper combination of auto- and cross-spectral averages over a several-hour period produces an estimate of the response of the infrasound system relative to that of the virtual reference. Measured coherence and the consistency between the magnitude and the phase provide quality checks on the process. [Funded by the US Army Space and Missile Defense Command

  18. Design of Multilevel Sequential Rotation Feeding Networks Used for Circularly Polarized Microstrip Antenna Arrays

    OpenAIRE

    Aixin Chen; Chuo Yang; Zhizhang (David) Chen; Yanjun Zhang; Yingyi He

    2012-01-01

    Sequential rotation feeding networks can significantly improve performance of the circularly polarized microstrip antenna array. In this paper, single, double, and multiple series-parallel sequential rotation feeding networks are examined. Compared with conventional parallel feeding structures, these multilevel feeding techniques present reduction of loss, increase of bandwidth, and improvement of radiation pattern and polarization purity. By using corner-truncated square patch as the array e...

  19. Array calibration of angularly dependent gain and phase uncertainties with carry-on instrumental sensors

    Institute of Scientific and Technical Information of China (English)

    WANG Buhong; WANG Yongliang; CHEN Hui; GUO Ying

    2004-01-01

    Array calibration with angularly dependent gain and phase uncertainties has long been a difficult problem. Although many array calibration methods have been reported extensively in the literature, they almost all assumed an angularly independent model for array uncertainties. Few calibration methods have been developed for the angularly dependent array uncertainties. A novel and efficient auto-calibration method for angularly dependent gain and phase uncertainties is proposed in this paper, which is called ISM (Instrumental Sensors Method). With the help of a few well-calibrated instrumental sensors, the ISM is able to achieve favorable and unambiguous direction-of-arrivals (DOAs) estimate and the corresponding angularly dependent gain and phase estimate simultaneously, even in the case of multiple non-disjoint sources. Since the mutual coupling and sensor position errors can all be described as angularly dependent gain/phase uncertainties, the ISM proposed still works in the presence of a combination of all these array perturbations. The ISM can be applied to arbitrary array geometries including linear arrays. The ISM is computationally efficient and requires only one-dimensional search, with no high-dimensional nonlinear search and convergence burden involved. Besides, no small error assumption is made, which is always an essential prerequisite for many existing array calibration techniques. The estimation performance of the ISM is analyzed theoretically and simulation results are provided to demonstrate the effectiveness and behavior of the proposed ISM.

  20. Precise calibration of a GNSS antenna array for adaptive beamforming applications.

    Science.gov (United States)

    Daneshmand, Saeed; Sokhandan, Negin; Zaeri-Amirani, Mohammad; Lachapelle, Gérard

    2014-05-30

    The use of global navigation satellite system (GNSS) antenna arrays for applications such as interference counter-measure, attitude determination and signal-to-noise ratio (SNR) enhancement is attracting significant attention. However, precise antenna array calibration remains a major challenge. This paper proposes a new method for calibrating a GNSS antenna array using live signals and an inertial measurement unit (IMU). Moreover, a second method that employs the calibration results for the estimation of steering vectors is also proposed. These two methods are applied to the receiver in two modes, namely calibration and operation. In the calibration mode, a two-stage optimization for precise calibration is used; in the first stage, constant uncertainties are estimated while in the second stage, the dependency of each antenna element gain and phase patterns to the received signal direction of arrival (DOA) is considered for refined calibration. In the operation mode, a low-complexity iterative and fast-converging method is applied to estimate the satellite signal steering vectors using the calibration results. This makes the technique suitable for real-time applications employing a precisely calibrated antenna array. The proposed calibration method is applied to GPS signals to verify its applicability and assess its performance. Furthermore, the data set is used to evaluate the proposed iterative method in the receiver operation mode for two different applications, namely attitude determination and SNR enhancement.

  1. Precise Calibration of a GNSS Antenna Array for Adaptive Beamforming Applications

    Directory of Open Access Journals (Sweden)

    Saeed Daneshmand

    2014-05-01

    Full Text Available The use of global navigation satellite system (GNSS antenna arrays for applications such as interference counter-measure, attitude determination and signal-to-noise ratio (SNR enhancement is attracting significant attention. However, precise antenna array calibration remains a major challenge. This paper proposes a new method for calibrating a GNSS antenna array using live signals and an inertial measurement unit (IMU. Moreover, a second method that employs the calibration results for the estimation of steering vectors is also proposed. These two methods are applied to the receiver in two modes, namely calibration and operation. In the calibration mode, a two-stage optimization for precise calibration is used; in the first stage, constant uncertainties are estimated while in the second stage, the dependency of each antenna element gain and phase patterns to the received signal direction of arrival (DOA is considered for refined calibration. In the operation mode, a low-complexity iterative and fast-converging method is applied to estimate the satellite signal steering vectors using the calibration results. This makes the technique suitable for real-time applications employing a precisely calibrated antenna array. The proposed calibration method is applied to GPS signals to verify its applicability and assess its performance. Furthermore, the data set is used to evaluate the proposed iterative method in the receiver operation mode for two different applications, namely attitude determination and SNR enhancement.

  2. Investigations on antenna array calibration algorithms for direction-of-arrival estimation

    Science.gov (United States)

    Eberhardt, Michael; Eschlwech, Philipp; Biebl, Erwin

    2016-09-01

    Direction-of-arrival (DOA) estimation algorithms deliver very precise results based on good and extensive antenna array calibration. The better the array manifold including all disturbances is known, the better the DOA estimation result. A simplification or ideally an omission of the calibration procedure has been a long pursued goal in the history of array signal processing. This paper investigates the practicability of some well known calibration algorithms and gives a deeper insight into existing obstacles. Further analysis on the validity of the common used data model is presented. A new effect in modeling errors is revealed and simulation results substantiate this theory.

  3. A New Calibration Method for Microphone Array with Gain, Phase, and Position Errors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Microphone array can be used in sound source localization and separation. But gain, phase, and position errors can seriously influence the performance of localization algorithms such as multiple signal classification (MUSIC) algorithm. In this paper, a new calibration method for microphone array with gain, phase, and position errors is proposed. Unlike traditional calibration methods for antenna array, the proposed method can be used in the broadband and near-field signal model such as microphone array with arbitrary sensor geometries in one plane. Computer simulations are presented and simulation results show the new method having good performance.

  4. Resolving phase ambiguities in the calibration of redundant interferometric arrays: implications for array design

    Science.gov (United States)

    Kurien, Binoy G.; Tarokh, Vahid; Rachlin, Yaron; Shah, Vinay N.; Ashcom, Jonathan B.

    2016-10-01

    We provide new results enabling robust interferometric image reconstruction in the presence of unknown aperture piston variation via the technique of redundant spacing calibration (RSC). The RSC technique uses redundant measurements of the same interferometric baseline with different pairs of apertures to reveal the piston variation among these pairs. In both optical and radio interferometry, the presence of phase-wrapping ambiguities in the measurements is a fundamental issue that needs to be addressed for reliable image reconstruction. In this paper, we show that these ambiguities affect recently developed RSC phasor-based reconstruction approaches operating on the complex visibilities, as well as traditional phase-based approaches operating on their logarithm. We also derive new sufficient conditions for an interferometric array to be immune to these ambiguities in the sense that their effect can be rendered benign in image reconstruction. This property, which we call wrap-invariance, has implications for the reliability of imaging via classical three-baseline phase closures as well as generalized closures. We show that wrap-invariance is conferred upon arrays whose interferometric graph satisfies a certain cycle-free condition. For cases in which this condition is not satisfied, a simple algorithm is provided for identifying those graph cycles which prevent its satisfaction. We apply this algorithm to diagnose and correct a member of a pattern family popular in the literature.

  5. Wideband Circularly Polarized SIW Antenna Array That Uses Sequential Rotation Feeding

    OpenAIRE

    Fang-Fang Fan; Ze-Hong Yan; Wei Wang

    2014-01-01

    A wideband right-handed circularly polarized (CP) substrate integrated waveguide- (SIW-) based diamond ring-slot antenna array at the X-band is presented in this study. The array consists of four elements that exhibit wideband impedance matching characteristics and good radiation performance. The array also employs a sequential rotation feeding method to achieve the wideband axial ratio (AR) bandwidth. The feeding network is based on the SIW power divider with a delay line related to sequenti...

  6. Method of array shape calibration based on time delay estimation using two auxiliary sources

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; WU Lixin; CUI Jie; Jim Lynch; Arthur Newhall

    2007-01-01

    As for a flexible horizontal array deployed in the sea, it is difficult to obtain each sensor's precise relative position. Therefore a method of array shape calibration is proposed.The method is described as follows. Firstly two separate auxiliary sources are deployed. Secondly time delay of each sensor's received signal is estimated. Finally, with the aid of GPS location of the sources and the horizontal array, relative sensor positions of the horizontal array can be determined. The estimation of relative sensor positions is unbiased. Simultaneously,simulation analysis has been done to estimate its standard variance, and the optimal flare angle of the two sources has been derived. Data of 2001 Asian Sea International Experiment have been used to validate the method. After array calibration, measured source azimuth angle agrees with the real one, and measured array gain agrees with the theoretical gain. In conclusion, the theoretical and experimental results both show that the method can determine each sensor's relative position precisely.

  7. Calibration of the Cherenkov Telescope Array using Cosmic Ray Electrons

    CERN Document Server

    Parsons, R D; Schoorlemmer, H

    2016-01-01

    Cosmic ray electrons represent a background for gamma-ray observations with Cherenkov telescopes, initiating air-showers which are difficult to distinguish from photon-initiated showers. This similarity, however, and the presence of cosmic ray electrons in every field observed, makes them potentially very useful for calibration purposes. Here we study the precision with which the relative energy scale and collection area/efficiency for photons can be established using electrons for a major next generation instrument such as CTA. We find that variations in collection efficiency on hour timescales can be corrected to better than 1%. Furthermore, the break in the electron spectrum at ~0.9 TeV can be used to calibrate the energy scale at the 3% level on the same timescale. For observations on the order of hours, statistical errors become negligible below a few TeV and allow for an energy scale cross-check with instruments such as CALET and AMS. Cosmic ray electrons therefore provide a powerful calibration tool, e...

  8. Recent Developments in Measuring Signal and Noise in Phased Array Feeds at CSIRO

    CERN Document Server

    Chippendale, A P; Bannister, K; Nikolic, N; Hotan, A W; Smart, K W; Shaw, R D; Hayman, D B; Hay, S G

    2016-01-01

    We describe recent developments in measuring both signal and noise in phased array feeds for radio astronomy at CSIRO. A number of new techniques are introduced and illustrated with a selection of results.

  9. Calibration and linearity verification of capacitance type cryo level indicators using cryogenically multiplexed diode array

    Science.gov (United States)

    Karunanithi, R.; Jacob, Subhash; Singh Gour, Abhay Singh; Das, M.; Nadig, D. S.; Prasad, M. V. N.

    2012-06-01

    In space application the precision level measurement of cryogenic liquids in the storage tanks is done using triple redundant capacitance level sensor, for control and safety point of view. The linearity of each sensor element depends upon the cylindricity and concentricity of the internal and external electrodes. The complexity of calibrating all sensors together has been addressed by two step calibration methodology which has been developed and used for the calibration of six capacitance sensors. All calibrations are done using Liquid Nitrogen (LN2) as a cryogenic fluid. In the first step of calibration, one of the elements of Liquid Hydrogen (LH2) level sensor is calibrated using 700mm eleven point discrete diode array. Four wire method has been used for the diode array. Thus a linearity curve for a single element of LH2 is obtained. In second step of calibration, using the equation thus obtained for the above sensor, it is considered as a reference for calibrating remaining elements of the same LH2 sensor and other level sensor (either Liquid Oxygen (LOX) or LH2). The elimination of stray capacitance for the capacitance level probes has been attempted. The automatic data logging of capacitance values through GPIB is done using LabVIEW 8.5.

  10. Development of an Experimental Phased Array Feed System and Algorithms for Radio Astronomy

    Science.gov (United States)

    Landon, Jonathan C.

    Phased array feeds (PAFs) are a promising new technology for astronomical radio telescopes. While PAFs have been used in other fields, the demanding sensitivity and calibration requirements in astronomy present unique new challenges. This dissertation presents some of the first astronomical PAF results demonstrating the lowest noise temperature and highest sensitivity at the time (66 Kelvin and 3.3 m^2/K, respectively), obtained using a narrowband (425 kHz bandwidth)prototype array of 19 linear co-polarized L-band dipoles mounted at the focus of the Green Bank 20 Meter Telescope at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. Results include spectral line detection of hydroxyl (OH) sources W49N and W3OH, and some of the first radio camera images made using a PAF, including an image of the Cygnus X region. A novel array Y-factor technique for measuring the isotropic noise response of the array is shown along with experimental measurements for this PAF. Statistically optimal beamformers (Maximum SNR and MVDR) are used throughout the work. Radio-frequency interference (RFI) mitigation is demonstrated experimentally using spatial cancelation with the PAF. Improved RFI mitigation is achieved in the challenging cases of low interference-to-noise ratio (INR) and moving interference by combining subspace projection (SP) beamforming with a polynomial model to track a rank 1 subspace. Limiting factors in SP are investigated including sample estimation error, subspace smearing, noise bias, and spectral scooping; each of these factors is overcome with the polynomial model and prewhitening. Numerical optimization leads to the polynomial subspace projection (PSP) method, and least-squares fitting to the series of dominant eigenvectors over a series of short term integrations (STIs) leads to the eigenvector polynomial subspace projection (EPSP) method. Expressions for the gradient, Hessian, and Jacobian are given for use in numerical optimization

  11. Optimum linear array for aperture synthesis imaging based on redundant spacing calibration

    Science.gov (United States)

    Liu, Li; He, Yuntao; Zhang, Jianguo; Jia, Huayu; Ma, Jun

    2014-05-01

    Aperture synthesis imaging has been proved to be attractive in surveillance and detection applications. Such an imaging process is inevitably subject to aberrations introduced by instrument defects and/or turbulent media. Redundant spacing calibration (RSC) technique allows continuous calibration of these errors at any electromagnetic wavelength. However, it is based on specially designed array, in which just enough redundancy is included to permit the successful implementation of RSC. A new design criterion for linear RSC array is described, which introduces coverage efficiency and redundancy efficiency factors, aiming to find the perfect configurations, which have as complete uv-plane coverage as possible while containing required redundancy. Optimum linear arrays for N (number of subapertures) up to 10 are listed based on simulated annealing algorithm. The comparisons with existing linear RSC arrays with equivalent subaperture number are implemented. Results show that the optimized arrays have better performance of both optical transfer function, point spread function, and object reconstruction with reasonable value of the matrix condition number. After that, linear arrays are used to construct two-dimensional (2-D) pseudo-Y-shaped RSC arrays, which give a way to design 2-D RSC arrays without exhaustive searches.

  12. Calibration of AFM cantilever stiffness: a microfabricated array of reflective springs.

    Science.gov (United States)

    Cumpson, P J Peter J; Zhdan, Peter; Hedley, John

    2004-08-01

    Calibration of the spring constant of atomic force microscope (AFM) cantilevers is necessary for the measurement of nanonewton and piconewton forces, which are critical to analytical applications of AFM in the analysis of polymer surfaces, biological structures and organic molecules. We have developed a compact and easy-to-use reference standard for this calibration. The new artifact consists of an array of 12 dual spiral-cantilever springs, each supporting a mirrored polycrystalline silicon disc of 160 microm in diameter. These devices were fabricated by a three-layer polysilicon surface micromachining method, including a reflective layer of gold on chromium. We call such an array a Microfabricated Array of Reference Springs (MARS). These devices have a number of advantages. Cantilever calibration using this device is straightforward and rapid. The devices have very small inertia, and are therefore resistant to shock and vibration. This means they need no careful treatment except reasonably clean laboratory conditions. The array spans the range of spring constant from around 0.16 to 11 N/m important in AFM, allowing almost all contact-mode AFM cantilevers to be calibrated easily and rapidly. Each device incorporates its own discrete gold mirror to improve reflectivity. The incorporation of a gold mirror both simplifies calibration of the devices themselves (via Doppler velocimetry) and allows interferometric calibration of the AFM z-axis using the apparent periodicity in the force-distance curve before contact. Therefore, from a single force-distance curve, taking about one second to acquire, one can calibrate the cantilever spring constant and, optionally, the z-axis scale. These are all the data one needs to make accurate and reliable force measurements. PMID:15231316

  13. Novel Phased Array Scanning Employing A Single Feed Without Using Individual Phase Shifters

    Science.gov (United States)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

    2012-01-01

    Phased arrays afford many advantages over mechanically steered systems. However, they are also more complex, heavy, and most of all costly. The high cost mainly originates from the complex feeding structure. This paper proposes a novel feeding scheme to eliminate all phase shifters and achieve scanning via one-dimensional motion. Beam scanning is achieved via a series fed array incorporating feeding transmission lines whose wave velocity can be mechanically adjusted. Along with the line design, ideal element impedances to be used in conjunction with the line are derived. Practical designs are shown which achieve scanning to +/-30deg from boresight. Finally, a prototype is fabricated and measured, demonstrating the concept.

  14. SCRLH-TL Based Sequential Rotation Feed Network for Broadband Circularly Polarized Antenna Array

    OpenAIRE

    Zong, B. F.; Wang, G. M.; Zeng, H Y; Wang, Y.W.; Wang, D

    2016-01-01

    In this paper, a broadband circularly polarized (CP) microstrip antenna array using composite right/left-handed transmission line (SCRLH-TL) based sequential rotation (SR) feed network is presented. The characteristics of a SCRLH-TL are initially investigated. Then, a broadband and low insertion loss 45º phase shifter is designed using the SCRLH-TL and the phase shifter is employed in constructing a SR feed network for CP antenna array. To validate the design method of the SR feed network, a ...

  15. Wideband Circularly Polarized SIW Antenna Array That Uses Sequential Rotation Feeding

    Directory of Open Access Journals (Sweden)

    Fang-Fang Fan

    2014-01-01

    Full Text Available A wideband right-handed circularly polarized (CP substrate integrated waveguide- (SIW- based diamond ring-slot antenna array at the X-band is presented in this study. The array consists of four elements that exhibit wideband impedance matching characteristics and good radiation performance. The array also employs a sequential rotation feeding method to achieve the wideband axial ratio (AR bandwidth. The feeding network is based on the SIW power divider with a delay line related to sequential rotation feeding. To validate our design, an antenna array is fabricated and measured. The measured impedance and AR bandwidths are 19.2% (VSWR<2 and 14.1% (AR<3 dB, respectively. Moreover, the antenna has a stable CP peak gain of more than 12 dBic from 10.1 GHz to 10.7 GHz.

  16. Calibrating short-timescale tropospheric phase fluctuations seen by a radio telescope: Limits from subreflector and Cassegrain feed ring radiometer placement

    Science.gov (United States)

    Linfield, Roger

    2002-10-01

    Water vapor radiometers (WVRs) measure tropospheric brightness temperatures and use those measurements to infer path delay. Calibration of short-timescale phase fluctuations at a radio telescope requires that the WVR and radio telescope sample a similar volume of the troposphere. Using a statistical (Kolmogorov frozen flow) model of tropospheric fluctuations, the short-timescale calibration capability of two WVR configurations has been quantified. The first configuration is a WVR mounted, with its own antenna, on the back side of the main radio telescope subreflector, giving a conical beam that is coaxial with the main cylindrical near-field beam of the large telescope. The second configuration uses a Cassegrain feed ring, with the WVR and radio astronomy feeds at different positions on the ring. This second configuration gives a cylindrical calibration near-field beam, offset in angle to the main cylindrical beam. An important application of short-timescale phase calibration is improving the coherence of high-frequency interferometric observations. For two cases of current/near future interest (86 GHz very long baseline interferometry with the Very Long Baseline Array; 350 GHz observations with the Atacama Large Millimeter Array, ALMA), useful calibration could be achieved with either geometry (coaxial conical beam or offset cylindrical beam). For a coaxial conical beam, a 2° WVR beam width would allow significant coherence improvement, but a beam width performance. For an offset cylindrical beam, the desired angular offset (on the sky) is 43 GHz Very Large Array observations, or <=0.3° for 350 GHz ALMA observations.

  17. The LED and fiber based calibration system for the photomultiplier array of SNO+

    International Nuclear Information System (INIS)

    A new external LED/fiber light injection calibration system was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. The goal of the calibration system is to allow an accurate and regular measurement of the photomultiplier array's performance, while minimizing the risk of radioactivity ingress. The choice in SNO+ was to use a set of optical fiber cables to convey into the detector the light pulses produced by external LEDs. The quality control was carried out using a modified test bench that was used in QC of optical fibers for TileCal/ATLAS. The optical fibers were characterized for transmission, timing and angular dispersions. This article describes the setups used for the characterization and quality control of the system based on LEDs and optical fibers and their results

  18. Method for array gain and phase uncertainties calibration based on ISM and ESPRIT

    Institute of Scientific and Technical Information of China (English)

    Liao Bin; Liao Guisheng

    2009-01-01

    A now method for array calibration of array gain and phase uncertainties, which severely degrade the performance of spatial spectrum estimation, is presented. The method is based on the idea of the instrumental sensors method (ISM), two well-calibrated sensors are added into the original array. By applying the principle of estimation of signal parameters via rotational invariance techniques (ESPRIT), the direction-of-arrivals (DOAs) and uncertainties can be estimated simultaneously through eigen-decomposition. Compared with the conventional ones, this now method has less computational complexity while has higher estimation precision, what's more, it can overcome the problem of ambiguity. Both theoretical analysis and computer simulations show the effectiveness of the proposed method.

  19. The calibration of cellphone camera-based colorimetric sensor array and its application in the determination of glucose in urine.

    Science.gov (United States)

    Jia, Ming-Yan; Wu, Qiong-Shui; Li, Hui; Zhang, Yu; Guan, Ya-Feng; Feng, Liang

    2015-12-15

    In this work, a novel approach that can calibrate the colors obtained with a cellphone camera was proposed for the colorimetric sensor array. The variations of ambient light conditions, imaging positions and even cellphone brands could all be compensated via taking the black and white backgrounds of the sensor array as references, thereby yielding accurate measurements. The proposed calibration approach was successfully applied to the detection of glucose in urine by a colorimetric sensor array. Snapshots of the glucose sensor array by a cellphone camera were calibrated by the proposed compensation method and the urine samples at different glucose concentrations were well discriminated with no confusion after a hierarchical clustering analysis. PMID:26275712

  20. Medicina array demonstrator: calibration and radiation pattern characterization using a UAV-mounted radio-frequency source

    Science.gov (United States)

    Pupillo, G.; Naldi, G.; Bianchi, G.; Mattana, A.; Monari, J.; Perini, F.; Poloni, M.; Schiaffino, M.; Bolli, P.; Lingua, A.; Aicardi, I.; Bendea, H.; Maschio, P.; Piras, M.; Virone, G.; Paonessa, F.; Farooqui, Z.; Tibaldi, A.; Addamo, G.; Peverini, O. A.; Tascone, R.; Wijnholds, S. J.

    2015-06-01

    One of the most challenging aspects of the new-generation Low-Frequency Aperture Array (LFAA) radio telescopes is instrument calibration. The operational LOw-Frequency ARray (LOFAR) instrument and the future LFAA element of the Square Kilometre Array (SKA) require advanced calibration techniques to reach the expected outstanding performance. In this framework, a small array, called Medicina Array Demonstrator (MAD), has been designed and installed in Italy to provide a test bench for antenna characterization and calibration techniques based on a flying artificial test source. A radio-frequency tone is transmitted through a dipole antenna mounted on a micro Unmanned Aerial Vehicle (UAV) (hexacopter) and received by each element of the array. A modern digital FPGA-based back-end is responsible for both data-acquisition and data-reduction. A simple amplitude and phase equalization algorithm is exploited for array calibration owing to the high stability and accuracy of the developed artificial test source. Both the measured embedded element patterns and calibrated array patterns are found to be in good agreement with the simulated data. The successful measurement campaign has demonstrated that a UAV-mounted test source provides a means to accurately validate and calibrate the full-polarized response of an antenna/array in operating conditions, including consequently effects like mutual coupling between the array elements and contribution of the environment to the antenna patterns. A similar system can therefore find a future application in the SKA-LFAA context.

  1. Calibrating the orientation between a microlens array and a sensor based on projective geometry

    Science.gov (United States)

    Su, Lijuan; Yan, Qiangqiang; Cao, Jun; Yuan, Yan

    2016-07-01

    We demonstrate a method for calibrating a microlens array (MLA) with a sensor component by building a plenoptic camera with a conventional prime lens. This calibration method includes a geometric model, a setup to adjust the distance (L) between the prime lens and the MLA, a calibration procedure for determining the subimage centers, and an optimization algorithm. The geometric model introduces nine unknown parameters regarding the centers of the microlenses and their images, whereas the distance adjustment setup provides an initial guess for the distance L. The simulation results verify the effectiveness and accuracy of the proposed method. The experimental results demonstrate the calibration process can be performed with a commercial prime lens and the proposed method can be used to quantitatively evaluate whether a MLA and a sensor is assembled properly for plenoptic systems.

  2. Reconfigurable Transmission Line for a Series-Fed Ku-Band Phased Array Using a Single Feed

    Science.gov (United States)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda. Felix, A.

    2013-01-01

    The paper presents a novel approach to realize a lowcost phased array using a simple feeding mechanism. Specifically, a single coplanar stripline (CPS) transmission line is used to feed the antenna array elements. By controlling the CPS's dielectric properties using a movable dielectric plunger, scanning is achieved. Due to its simplicity, single feed, and no phase shifters, this approach leads to a dramatic reduction in cost which does not scale for larger arrays.

  3. Indirect calibration of a large microphone array for in-duct acoustic measurements

    Science.gov (United States)

    Leclère, Q.; Pereira, A.; Finez, A.; Souchotte, P.

    2016-08-01

    This paper addresses the problem of in situ calibration of a pin hole-mounted microphone array for in-duct acoustic measurements. One approach is to individually measure the frequency response of each microphone, by submitting the probe to be calibrated and a reference microphone to the same pressure field. Although simple, this task may be very time consuming for large microphone arrays and eventually suffer from lack of access to microphones once they are installed on the test bench. An alternative global calibration procedure is thus proposed in this paper. The approach is based on the fact that the acoustic pressure can be expanded onto an analytically known spatial basis. A projection operator is defined allowing the projection of measurements onto the duct modal basis. The main assumption of the method is that the residual resulting from the difference between actual and projected measurements is mainly dominated by calibration errors. An iterative procedure to estimate the calibration factors of each microphone is proposed and validated through an experimental set-up. In addition, it is shown that the proposed scheme allows an optimization of physical parameters such as the sound speed and parameters associated to the test bench itself, such as the duct radius or the termination reflection coefficient.

  4. High Gain Slot Array with Fabry-Perot Cavity Feeding Circuit

    Directory of Open Access Journals (Sweden)

    Halim Boutayeb

    2016-01-01

    Full Text Available A new approach for designing slot arrays using a Fabry-Perot cavity for the feeding circuit is presented. The proposed array has simpler and smaller feeding circuit compared to conventional feeding networks that have multiple dividers or combiners. The dividers and combiners are usually sources of losses. In addition, the profile of the proposed array is not limited by the half-wavelength resonance condition that exists for Fabry-Perot resonator antennas based on partially reflecting surfaces. The operating frequency is not sensitive to the profile of the antenna. A small profile can be achieved without the utilization of an artificial magnetic conductor or a substrate with high dielectric constant. To validate the proposed approach, full-wave numerical results are presented at 5.8 GHz showing good impedance matching, a high gain of about 22 dB, and an efficiency of 76%.

  5. Power Pattern Sensitivity to Calibration Errors and Mutual Coupling in Linear Arrays through Circular Interval Arithmetics.

    Science.gov (United States)

    Anselmi, Nicola; Salucci, Marco; Rocca, Paolo; Massa, Andrea

    2016-01-01

    The sensitivity to both calibration errors and mutual coupling effects of the power pattern radiated by a linear array is addressed. Starting from the knowledge of the nominal excitations of the array elements and the maximum uncertainty on their amplitudes, the bounds of the pattern deviations from the ideal one are analytically derived by exploiting the Circular Interval Analysis (CIA). A set of representative numerical results is reported and discussed to assess the effectiveness and the reliability of the proposed approach also in comparison with state-of-the-art methods and full-wave simulations. PMID:27258274

  6. A comparative study of feed impedances of a circular and three different spiral antenna arrays

    Science.gov (United States)

    Ramachandra, V.; Dey, K. K.; Khastgir, P.

    1982-08-01

    Mathematical derivation of feed impedances of the dipole radiators of a circular and three different spiral arrays has been made for both constant and progressive phase distributions. A set of graphs, which show the variations of these impedances and their components from radiator to radiator, has been obtained. Spiral distributions of impedances can be observed on the Argand diagram in the cases of the three spiral arrays.

  7. The calibration system for the photomultiplier array of the SNO+ experiment

    CERN Document Server

    Alves, R; Bradbury, S; Carvalho, J; Chauhan, D; Clark, K; Coulter, I; Descamps, F; Falk, E; Gurriana, L; Kraus, C; Lefeuvre, G; Maio, A; Maneira, J; Mottram, M; Peeters, S; Rose, J; Seabra, L; Sinclair, J; Skensved, P; Waterfield, J; White, R; Wilson, J R

    2014-01-01

    A light injection system using LEDs and optical fibres was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. Large volume, non-segmented, low-background detectors for rare event physics, such as the multi-purpose SNO+ experiment, need a calibration system that allow an accurate and regular measurement of the performance parameters of their photomultiplier arrays, while minimising the risk of radioactivity ingress. The design implemented for SNO+ uses a set of optical fibres to inject light pulses from external LEDs into the detector. The design, fabrication and installation of this light injection system, as well as the first commissioning tests, are described in this paper. Monte Carlo simulations were compared with the commissioning test results, confirming that the system meets the performance requirements.

  8. New method for the time calibration of an interferometric radio antenna array

    CERN Document Server

    Schröder, F G; Bähren, L; Blümer, J; Bozdog, H; Falcke, H; Haungs, A; Horneffer, A; Huege, T; Isar, P G; Krömer, O; Nehls, S; 10.1016/j.nima.2010.01.072

    2010-01-01

    Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative del...

  9. Simplified calibration of single-plunge bipolar electrode array for field measurement during defibrillation.

    Science.gov (United States)

    Deale, O Carlton; Ng, Kwong T; Kim-Van Housen, Ellen J; Lerman, Bruce B

    2002-10-01

    In an earlier study, the authors presented a calibration technique for a triaxial bipolar electrode array (EA) that used 72 data points collected during a global sweep of the electric field vector relative to the EA axes. Although necessary for the initial characterization of the EAs, this data requirement has to be significantly reduced for the technique to become a practical tool. Therefore, in the present study, an analysis is performed to determine the relation between the number of data points used in the calibration and the mean root-mean-square error. The analysis shows that 18 data points can produce results nearly identical to those obtained with the 72-point calibration, thus reducing the required amount of data fourfold. PMID:12374347

  10. Flasher and muon-based calibration of the GCT telescopes proposed for the Cherenkov Telescope Array

    CERN Document Server

    Brown, Anthony M; Chadwick, Paula M; Daniel, Michael; White, Richard

    2015-01-01

    The GCT is a dual-mirror Small-Sized-Telescope prototype proposed for the Cherenkov Telescope Array. Calibration of the GCT's camera is primarily achieved with LED-based flasher units capable of producing $\\sim4$ ns FWHM pulses of 400 nm light across a large dynamic range, from 0.1 up to 1000 photoelectrons. The flasher units are housed in the four corners of the camera's focal plane and illuminate it via reflection from the secondary mirror. These flasher units are adaptable to allow several calibration scenarios to be accomplished: camera flat-fielding, linearity measurements (up to and past saturation), and gain estimates from both single pe measurements and from the photon statistics at various high illumination levels. In these proceedings, the performance of the GCT flashers is described, together with ongoing simulation work to quantify the efficiency of using muon rings as an end-to-end calibration for the optical throughput of the GCT.

  11. Techniques And Results For The Calibration Of The MST Prototype For The Cherenkov Telescope Array

    CERN Document Server

    ,

    2016-01-01

    The next generation instrument for ground-based gamma-ray astronomy will be the Cherenkov Telescope Array (CTA), consisting of approximately 100 telescopes in three sizes, built on two sites with one each in the Northern and Southern Hemi- spheres. Up to 40 of these will be Medium Size Telescopes (MSTs) which will dominate sensitivity in the core energy range. Since 2012, a full size mechanical prototype for the modified 12 m Davies-Cotton design MST has been in operation in Berlin. This doc- ument describes the techniques which have been implemented to calibrate and optimise the mechanical and optical performance of the prototype, and gives the results of over three years of observations and measurements. Pointing calibration techniques will be discussed, along with the development of a bending model, and calibration of the CCD cameras used for pointing measurements. Additionally alignment of mirror segments using the Bokeh method is shown.

  12. Novel Calibration Method for Switched Capacitor Arrays Enables Time Measurements with Sub- Picosecond Resolution

    CERN Document Server

    Stricker-Shaver, D A; Pichler, B J

    2014-01-01

    Switched capacitor arrays ASICs are becoming more and more popular for the readout of detector signals, since the sampling frequency of typically several gigasamples per second allows excellent pile-up rejection and time measurements. They suffer however from the fact that their sampling bins are not equidistant in time, given by limitations of the chip process. In the past, this limited time measurements of optimal signals to about 5-25 ps in accuracy, depending on the specific chip, even after careful time calibrations. This paper introduces a novel time calibration, which allows pushing this limit below 1 ps, and also determines the true sampling speed. Various test measurements with different boards based on the DRS4 ASIC indicate that the new calibration is valid over a wide temperature range and stable over time.

  13. Calibration Scheme for Large Kinetic Inductance Detector Arrays Based on Readout Frequency Response

    Science.gov (United States)

    Bisigello, L.; Yates, S. J. C.; Murugesan, V.; Baselmans, J. J. A.; Baryshev, A. M.

    2016-07-01

    Microwave kinetic inductance detector (MKID) provides a way to build large ground-based sub-mm instruments such as NIKA and A-MKID. For such instruments, therefore, it is important to understand and characterize the response to ensure good linearity and calibration over a wide dynamic range. We propose to use the MKID readout frequency response to determine the MKID responsivity to an input optical source power. A signal can be measured in a KID as a change in the phase of the readout signal with respect to the KID resonant circle. Fundamentally, this phase change is due to a shift in the KID resonance frequency, in turn due to a radiation induced change in the quasiparticle number in the superconducting resonator. We show that the shift in resonant frequency can be determined from the phase shift by using KID phase versus frequency dependence using a previously measured resonant frequency. Working in this calculated resonant frequency, we gain near linearity and constant calibration to a constant optical signal applied in a wide range of operating points on the resonance and readout powers. This calibration method has three particular advantages: first, it is fast enough to be used to calibrate large arrays, with pixel counts in the thousands of pixels; second, it is based on data that are already necessary to determine KID positions; third, it can be done without applying any optical source in front of the array.

  14. A compact array calibrator to study the feasibility of acoustic neutrino detection

    Directory of Open Access Journals (Sweden)

    Ardid M.

    2016-01-01

    Full Text Available Underwater acoustic detection of ultra-high-energy neutrinos was proposed already in 1950s: when a neutrino interacts with a nucleus in water, the resulting particle cascade produces a pressure pulse that has a bipolar temporal structure and propagates within a flat disk-like volume. A telescope that consists of thousands of acoustic sensors deployed in the deep sea can monitor hundreds of cubic kilometres of water looking for these signals and discriminating them from acoustic noise. To study the feasibility of the technique it is critical to have a calibrator able to mimic the neutrino “signature” that can be operated from a vessel. Due to the axial-symmetry of the signal, their very directive short bipolar shape and the constraints of operating at sea, the development of such a calibrator is very challenging. Once the possibility of using the acoustic parametric technique for this aim was validated with the first compact array calibrator prototype, in this paper we describe the new design for such a calibrator composed of an array of piezo ceramic tube transducers emitting in axial direction.

  15. A compact array calibrator to study the feasibility of acoustic neutrino detection

    Science.gov (United States)

    Ardid, M.; Camarena, F.; Felis, I.; Herrero, A.; Llorens, C. D.; Martínez-Mora, J.; Saldaña, M.

    2016-04-01

    Underwater acoustic detection of ultra-high-energy neutrinos was proposed already in 1950s: when a neutrino interacts with a nucleus in water, the resulting particle cascade produces a pressure pulse that has a bipolar temporal structure and propagates within a flat disk-like volume. A telescope that consists of thousands of acoustic sensors deployed in the deep sea can monitor hundreds of cubic kilometres of water looking for these signals and discriminating them from acoustic noise. To study the feasibility of the technique it is critical to have a calibrator able to mimic the neutrino "signature" that can be operated from a vessel. Due to the axial-symmetry of the signal, their very directive short bipolar shape and the constraints of operating at sea, the development of such a calibrator is very challenging. Once the possibility of using the acoustic parametric technique for this aim was validated with the first compact array calibrator prototype, in this paper we describe the new design for such a calibrator composed of an array of piezo ceramic tube transducers emitting in axial direction.

  16. Two Elements Elliptical Slot CDRA Array with Corporate Feeding For X-Band Applications

    Directory of Open Access Journals (Sweden)

    Abdulkareem S. Abdullah

    2014-06-01

    Full Text Available In this paper, a compact two-element cylindrical dielectric resonator antenna (CDRA array with corporate feeding is proposed for X-band applications. The dielectric resonator antenna (DRA array is excited by a microstrip feeder using an efficient aperture-coupled method. The designed array antenna is analyzed using a CST microwave studio. The fabricated sample of the proposed CDRA antenna array showed bandwidth extending from 10.42GHz to 12.84GHz (20.8%. The achieved array gain has a maximum of 9.29dBi at frequency of 10.7GHz. This is about 2.06dBi enhancement of the gain in comparison with a single pellet CDRA. The size of the whole antenna structure is about 5050mm2.

  17. Spatio-Temporal Equalizer for a Receiving-Antenna Feed Array

    Science.gov (United States)

    Mukai, Ryan; Lee, Dennis; Vilnrotter, Victor

    2010-01-01

    A spatio-temporal equalizer has been conceived as an improved means of suppressing multipath effects in the reception of aeronautical telemetry signals, and may be adaptable to radar and aeronautical communication applications as well. This equalizer would be an integral part of a system that would also include a seven-element planar array of receiving feed horns centered at the focal point of a paraboloidal antenna that would be nominally aimed at or near the aircraft that would be the source of the signal that one seeks to receive (see Figure 1). This spatio-temporal equalizer would consist mostly of a bank of seven adaptive finite-impulse-response (FIR) filters one for each element in the array - and the outputs of the filters would be summed (see Figure 2). The combination of the spatial diversity of the feedhorn array and the temporal diversity of the filter bank would afford better multipath-suppression performance than is achievable by means of temporal equalization alone. The seven-element feed array would supplant the single feed horn used in a conventional paraboloidal ground telemetry-receiving antenna. The radio-frequency telemetry signals re ceiv ed by the seven elements of the array would be digitized, converted to complex baseband form, and sent to the FIR filter bank, which would adapt itself in real time to enable reception of telemetry at a low bit error rate, even in the presence of multipath of the type found at many flight test ranges.

  18. Design and calibration of a six-axis MEMS sensor array for use in scoliosis correction surgery

    International Nuclear Information System (INIS)

    A six-axis sensor array has been developed to quantify the 3D force and moment loads applied in scoliosis correction surgery. Initially this device was developed to be applied during scoliosis correction surgery and augmented onto existing surgical instrumentation, however, use as a general load sensor is also feasible. The development has included the design, microfabrication, deployment and calibration of a sensor array. The sensor array consists of four membrane devices, each containing piezoresistive sensing elements, generating a total of 16 differential voltage outputs. The calibration procedure has made use of a custom built load application frame, which allows quantified forces and moments to be applied and compared to the outputs from the sensor array. Linear or non-linear calibration equations are generated to convert the voltage outputs from the sensor array back into 3D force and moment information for display or analysis. (papers)

  19. Design and calibration of a six-axis MEMS sensor array for use in scoliosis correction surgery

    Science.gov (United States)

    Benfield, David; Yue, Shichao; Lou, Edmond; Moussa, Walied A.

    2014-08-01

    A six-axis sensor array has been developed to quantify the 3D force and moment loads applied in scoliosis correction surgery. Initially this device was developed to be applied during scoliosis correction surgery and augmented onto existing surgical instrumentation, however, use as a general load sensor is also feasible. The development has included the design, microfabrication, deployment and calibration of a sensor array. The sensor array consists of four membrane devices, each containing piezoresistive sensing elements, generating a total of 16 differential voltage outputs. The calibration procedure has made use of a custom built load application frame, which allows quantified forces and moments to be applied and compared to the outputs from the sensor array. Linear or non-linear calibration equations are generated to convert the voltage outputs from the sensor array back into 3D force and moment information for display or analysis.

  20. Comparison and calibration of transcriptome data from RNA-Seq and tiling arrays

    Directory of Open Access Journals (Sweden)

    Reinke Valerie

    2010-06-01

    Full Text Available Abstract Background Tiling arrays have been the tool of choice for probing an organism's transcriptome without prior assumptions about the transcribed regions, but RNA-Seq is becoming a viable alternative as the costs of sequencing continue to decrease. Understanding the relative merits of these technologies will help researchers select the appropriate technology for their needs. Results Here, we compare these two platforms using a matched sample of poly(A-enriched RNA isolated from the second larval stage of C. elegans. We find that the raw signals from these two technologies are reasonably well correlated but that RNA-Seq outperforms tiling arrays in several respects, notably in exon boundary detection and dynamic range of expression. By exploring the accuracy of sequencing as a function of depth of coverage, we found that about 4 million reads are required to match the sensitivity of two tiling array replicates. The effects of cross-hybridization were analyzed using a "nearest neighbor" classifier applied to array probes; we describe a method for determining potential "black list" regions whose signals are unreliable. Finally, we propose a strategy for using RNA-Seq data as a gold standard set to calibrate tiling array data. All tiling array and RNA-Seq data sets have been submitted to the modENCODE Data Coordinating Center. Conclusions Tiling arrays effectively detect transcript expression levels at a low cost for many species while RNA-Seq provides greater accuracy in several regards. Researchers will need to carefully select the technology appropriate to the biological investigations they are undertaking. It will also be important to reconsider a comparison such as ours as sequencing technologies continue to evolve.

  1. SCRLH-TL Based Sequential Rotation Feed Network for Broadband Circularly Polarized Antenna Array

    Directory of Open Access Journals (Sweden)

    B. F. Zong

    2016-04-01

    Full Text Available In this paper, a broadband circularly polarized (CP microstrip antenna array using composite right/left-handed transmission line (SCRLH-TL based sequential rotation (SR feed network is presented. The characteristics of a SCRLH-TL are initially investigated. Then, a broadband and low insertion loss 45º phase shifter is designed using the SCRLH-TL and the phase shifter is employed in constructing a SR feed network for CP antenna array. To validate the design method of the SR feed network, a 2×2 antenna array comprising sequentially rotated coupled stacked CP antenna elements is designed, fabricated and measured. Both the simulated and measured results indicate that the performances of the antenna element are further enhanced when the SR network is used. The antenna array exhibits the VSWR less than 1.8 dB from 4 GHz to 7 GHz and the 3 dB axial ratio (AR from 4.4 GHz to 6.8 GHz. Also, high peak gain of 13.7 dBic is obtained. Besides, the normalized radiation patterns at the operating frequencies are symmetrical and the side lobe levels are low at φ=0º and φ=90º.

  2. A novel sub-camera array model for calibrating multi-mirror catadioptric systems

    International Nuclear Information System (INIS)

    The omni-directional catadioptric camera composed of multiple mirrors is a powerful tool that can acquire multiple wide field-of-view images and reconstruct the scene in a single shot. However, the non-central nature of the system poses significant challenges to the task of calibration. A novel off-center spherical projection (OCSP)-based sub-camera array model is proposed in this paper to address this problem. By inducing a movable spherical projection center in the traditional unified model, the OCSP sub-camera can efficiently deal with large misalignments that exist in multi-mirror systems. An efficient calibration method and the initialization algorithm are also presented. With the new model, calibration can be completed conveniently without the aid of a priori information on the mirrors and camera. The model is also compatible with traditional multi-view geometry, making 3D reconstruction straightforward for non-central systems. Experiments based on synthetic and real data on various types of mirrors show promising calibration results and thus verify the effectiveness of the method. (paper)

  3. Pointing Calibration for the Cherenkov Telescope Array Medium Size Telescope Prototype

    CERN Document Server

    Oakes, Louise; Baehr, Juergen; Gruenewald, Sandra; Raeck, Tobias; Schlenstedt, Stefan; Schubert, Anja; Schwanke, Ullrich

    2013-01-01

    Pointing calibration is an offline correction applied in order to obtain the true pointing direction of a telescope. The Cherenkov Telescope Array (CTA) aims to have the precision to determine the position of point-like as well as slightly extended sources, with the goal of systematic errors less than 7 arc seconds in space angle. This poster describes the pointing calibration concept being developed for the CTA Medium Size Telescope (MST) prototype at Berlin-Adlershof, showing test results and preliminary measurements. The MST pointing calibration method uses two CCD cameras, mounted on the telescope dish, to determine the true pointing of the telescope. The "Lid CCD" is aligned to the optical axis of the telescope, calibrated with LEDs on the dummy gamma-camera lid; the "Sky CCD" is pre-aligned to the Lid CCD and the transformation between the Sky and Lid CCD camera fields of view is precisely modelled with images from special pointing runs which are also used to determine the pointing model. During source ...

  4. Calibration and simulation of a gamma array for DRAGON at ISAC

    CERN Document Server

    Gigliotti, D G; Hussein, A H

    2003-01-01

    A gamma ray detector has been built for the DRAGON facility at TRIUMF to detect the gamma ray emitted in astrophysically important proton and alpha radiative capture reactions. The gamma detector was designed to balance cost with maximum solid angle coverage and efficiency. To study the properties of the current design, GEANT simulations are being carried out and compared with prototype measurements using calibration sources and radioactive beams supplied by ISAC. Simulations will be compared with data allowing a realistic simulation to be produced. This modified simulation will then be used to provide efficiency predictions of the gamma array when an actual experiment's parameters are inputted. Using the simulated efficiency of the array, cross sections for radiative capture can be calculated from the measured gamma ray yields, for the individual reactions. The following will outline some initial results of background suppression of beam related experiments. Also shown, are some preliminary comparison of poi...

  5. Calibration of the Neutral Current Detection Array in the SNO experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cox, G.A. [University of Washington, Seattle, US (United States); Cleveland, B.T. [University of Oxford, Oxford (United Kingdom); Di Marco, M. [Queen' s University, Kingston (Canada); present address: University of Geneva, Geneva (Switzerland); Evans, H.C.; Guillian, E.; Hallin, A.L. [Queen' s University, Kingston (Canada); Huang, M. [University of Texas, Austin (United States); Howard, C. [Queen' s University, Kingston (Canada); Jelley, N.A. [University of Oxford, Oxford (United Kingdom); Law, J. [University of Guelph, Guelph (Canada); Loach, J.C. [University of Oxford, Oxford (United Kingdom); Lawrence Berkeley National Laboratory, Berkeley (United States); O' Keeffe, H.M. [University of Oxford, Oxford (United Kingdom); Kraus, C.; Krauss, C.B. [Queen' s University, Kingston (Canada); McGee, S. [present address: University of Geneva, Geneva, Switserland (Switzerland); Peeters, S.J.M., E-mail: s.peeters1@physics.ox.ac.uk [University of Oxford, Oxford (United Kingdom); Prior, G. [University of Texas, Austin (United States); Lawrence Berkeley National Laboratory, Berkeley (United States); Rielage, K. [Los Alamos National Laboratory, Los Alamos (United States); Reitzner, D. [University of Guelph, Guelph (Canada); Skensved, P. [Queen' s University, Kingston (Canada); and others

    2011-12-15

    Since November 25th, 2004, the Sudbury Neutrino Observatory has been taking production data in its third and final phase. For this phase a 'Neutral-Current Detection (NCD) Array', consisting of 36 strings of {sup 3}He proportional counters and 4 strings of {sup 4}He proportional counters, was deployed in SNO's D{sub 2}O volume. It supplements the Cherenkov detector, consisting of 9456 photomultiplier tubes, present in the previous two phases by offering an independent measurement of the solar neutral current rate. The {sup 3}He counters detect neutrons from neutrino-deuteron neutral current interactions in the D{sub 2}O. We describe the calibration of this array.

  6. Measured Sensitivity of the First Mark II Phased Array Feed on an ASKAP Antenna

    CERN Document Server

    Chippendale, A P; Beresford, R J; Hampson, G A; Macleod, A; Shaw, R D; Brothers, M L; Cantrall, C; Forsyth, A R; Hay, S G; Leach, M

    2015-01-01

    This paper presents the measured sensitivity of CSIRO's first Mk. II phased array feed (PAF) on an ASKAP antenna. The Mk. II achieves a minimum system-temperature-over-efficiency $T_\\mathrm{sys}/\\eta$ of 78 K at 1.23 GHz and is 95 K or better from 835 MHz to 1.8 GHz. This PAF was designed for the Australian SKA Pathfinder telescope to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array (SKA).

  7. Calibration of Photomultiplier Tubes for the Fluorescence Detector of Telescope Array Experiment using a Rayleigh Scattered Laser Beam

    CERN Document Server

    Kawana, Shingo; Fujii, Toshihiro; Fukushima, Masaki; Inoue, Naoya; Matthews, John N; Ogio, Shoichi; Sagawa, Hiroyuki; Taketa, Akimichi; Takita, Masato; Thomas, Stan B; Tokuno, Hisao; Tsunesada, Yoshiki; Udo, Shigeharu; Wiencke, Lawrence R

    2012-01-01

    We performed photometric calibration of the PhotoMultiplier Tube (PMT) and readout electronics used for the new fluorescence detectors of the Telescope Array (TA) experiment using Rayleigh scattered photons from a pulsed nitrogen laser beam. The experimental setup, measurement procedure, and results of calibration are described. The total systematic uncertainty of the calibration is estimated to be 7.5%. An additional uncertainty of 3.7% is introduced by the transport of the calibrated PMTs from the laboratory to the TA experimental site.

  8. Calibration of photomultiplier tubes for the fluorescence detector of telescope array experiment using a Rayleigh scattered laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Kawana, Shingo, E-mail: kawana@crsgm1.crinoue.phy.saitama-u.ac.jp [Graduate School of Science and Engineering, Saitama University, Saitama 338-8570 (Japan); Sakurai, Nobuyuki; Fujii, Toshihiro [Graduate School of Science, Osaka City University, Sumiyoshi, Osaka 558-8585 (Japan); Fukushima, Masaki [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Inoue, Naoya [Graduate School of Science and Engineering, Saitama University, Saitama 338-8570 (Japan); Matthews, John N. [Department of Physics and High Energy Astrophysics Institute, University of Utah, Salt Lake City, UT 84112 (United States); Ogio, Shoichi [Graduate School of Science, Osaka City University, Sumiyoshi, Osaka 558-8585 (Japan); Sagawa, Hiroyuki [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Taketa, Akimichi [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Earthquake Research Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0032 (Japan); Takita, Masato [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Thomas, Stan B. [Department of Physics and High Energy Astrophysics Institute, University of Utah, Salt Lake City, UT 84112 (United States); Tokuno, Hisao [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Interactive Research Center of Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Tsunesada, Yoshiki [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Udo, Shigeharu [Kanagawa University, Yokohama, Kanagawa 221-8624 (Japan); Wiencke, Lawrence R. [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States)

    2012-07-21

    We performed photometric calibration of the PhotoMultiplier Tube (PMT) and readout electronics used for the new fluorescence detectors of the Telescope Array (TA) experiment using Rayleigh scattered photons from a pulsed nitrogen laser beam. The experimental setup, measurement procedure, and results of calibration are described. The total systematic uncertainty of the calibration is estimated to be 7.2%. An additional uncertainty of 3.7% is introduced by the transport of the calibrated PMTs from the laboratory to the TA experimental site.

  9. Calibration of photomultiplier tubes for the fluorescence detector of telescope array experiment using a Rayleigh scattered laser beam

    Science.gov (United States)

    Kawana, Shingo; Sakurai, Nobuyuki; Fujii, Toshihiro; Fukushima, Masaki; Inoue, Naoya; Matthews, John N.; Ogio, Shoichi; Sagawa, Hiroyuki; Taketa, Akimichi; Takita, Masato; Thomas, Stan B.; Tokuno, Hisao; Tsunesada, Yoshiki; Udo, Shigeharu; Wiencke, Lawrence R.

    2012-07-01

    We performed photometric calibration of the PhotoMultiplier Tube (PMT) and readout electronics used for the new fluorescence detectors of the Telescope Array (TA) experiment using Rayleigh scattered photons from a pulsed nitrogen laser beam. The experimental setup, measurement procedure, and results of calibration are described. The total systematic uncertainty of the calibration is estimated to be 7.2%. An additional uncertainty of 3.7% is introduced by the transport of the calibrated PMTs from the laboratory to the TA experimental site.

  10. Calibration and testing of a prototype of the JEM-EUSO telescope on Telescope Array site

    Directory of Open Access Journals (Sweden)

    Tsunesada Y.

    2013-06-01

    Full Text Available Aim of the TA-EUSO project is to install a prototype of the JEM-EUSO telescope on the Telescope Array site in Black Rock Mesa, Utah and perform observation of natural and artificial ultraviolet light. The detector consists of one Photo Detector Module (PDM, identical to the 137 present on the JEM-EUSO focal surface. Each PDM is composed by 36 Hamamatsu multi-anode photomultipliers (64 channels per tube, for a total of 2304 channels. Front-End readout is performed by 36 ASICS, with trigger and readout tasks performed by two FPGA boards that send the data to a CPU and storage system. Two, 1 meter side square Fresnel lenses provide a field-of-view of 8 degrees. The telescope will be housed in a container located in front of the fluorescence detector of the Telescope Array collaboration, looking in the direction of the ELF (Electron Light Source and CLF (Central Laser Facility. Aim of the project is to calibrate the response function of the EUSO telescope with the TA fluorescence detector in presence of a shower of known intensity and distribution. An initial run of about six months starting from end 2012 is foreseen, during which we expect to observe, triggered by TA electronics, a few cosmic ray events which will be used to further refine the calibration of the EUSO-Ground with TA. Medium term plans include the increase of the number of PDM and therefore the field of view.

  11. New method for the time calibration of an interferometric radio antenna array

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, F.G., E-mail: frank.schroeder@kit.ed [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Asch, T. [Karlsruhe Institute of Technology (KIT), Institut fuer Prozessdatenverarbeitung und Elektronik, 76021 Karlsruhe (Germany); Baehren, L. [Radboud University Nijmegen, Department of Astrophysics, 6525 ED Nijmegen (Netherlands); Bluemer, J. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Karlsruhe Institute of Technology (KIT), Institut fuer Experimentelle Kernphysik, 76021 Karlsruhe (Germany); Bozdog, H. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Falcke, H. [Radboud University Nijmegen, Department of Astrophysics, 6525 ED Nijmegen (Netherlands); ASTRON, 7990 AA Dwingeloo (Netherlands); Haungs, A. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Horneffer, A. [Radboud University Nijmegen, Department of Astrophysics, 6525 ED Nijmegen (Netherlands); Huege, T.; Isar, P.G. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Kroemer, O. [Karlsruhe Institute of Technology (KIT), Institut fuer Prozessdatenverarbeitung und Elektronik, 76021 Karlsruhe (Germany); Nehls, S. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany)

    2010-04-11

    Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative delays between the antennas can be detected and corrected for at each recorded event by measuring the phases at the beacon frequencies.

  12. Theory of a Traveling Wave Feed for a Planar Slot Array Antenna

    Science.gov (United States)

    Rengarajan, Sembiam

    2012-01-01

    Planar arrays of waveguide-fed slots have been employed in many radar and remote sensing applications. Such arrays are designed in the standing wave configuration because of high efficiency. Traveling wave arrays can produce greater bandwidth at the expense of efficiency due to power loss in the load or loads. Traveling wave planar slot arrays may be designed with a long feed waveguide consisting of centered-inclined coupling slots. The feed waveguide is terminated in a matched load, and the element spacing in the feed waveguide is chosen to produce a beam squinted from the broadside. The traveling wave planar slot array consists of a long feed waveguide containing resonant-centered inclined coupling slots in the broad wall, coupling power into an array of stacked radiating waveguides orthogonal to it. The radiating waveguides consist of longitudinal offset radiating slots in a standing wave configuration. For the traveling wave feed of a planar slot array, one has to design the tilt angle and length of each coupling slot such that the amplitude and phase of excitation of each radiating waveguide are close to the desired values. The coupling slot spacing is chosen for an appropriate beam squint. Scattering matrix parameters of resonant coupling slots are used in the design process to produce appropriate excitations of radiating waveguides with constraints placed only on amplitudes. Since the radiating slots in each radiating waveguide are designed to produce a certain total admittance, the scattering (S) matrix of each coupling slot is reduced to a 2x2 matrix. Elements of each 2x2 S-matrix and the amount of coupling into the corresponding radiating waveguide are expressed in terms of the element S11. S matrices are converted into transmission (T) matrices, and the T matrices are multiplied to cascade the coupling slots and waveguide sections, starting from the load end and proceeding towards the source. While the use of non-resonant coupling slots may provide an

  13. Binary Pseudo-Random Gratings and Arrays for Calibration of Modulation Transfer Functions of Surface Profilometers

    Energy Technology Data Exchange (ETDEWEB)

    Barber, S.K.; Takacs, P.; Anderson, E.D.; Cambie, R.; McKinney, W.R.; Stover, J.C.; Voronov, D.L.; Yashchuk, V.V.

    2009-10-20

    A technique for precise measurement of the modulation transfer function (MTF), suitable for characterization of a broad class of surface profilometers, is investigated in detail. The technique suggested in papers Yashchuk et al. (2007), Yashchuk et al. (2008) is based on use of binary pseudo-random (BPR) gratings and arrays as standard MTF test surfaces. Unlike most conventional test surfaces, BPR gratings and arrays possess white-noise-like inherent power spectral densities (PSD), allowing the direct determination of the one- and two-dimensional MTF, respectively, with a sensitivity uniform over the entire spatial frequency range of a profiler. In the cited work, a one-dimensional realization of the suggested method based on use of BPR gratings has been demonstrated. Here, a high performance of the MTF calibration technique is demonstrated via cross comparison measurements of a number of two-dimensional BPR arrays using two different interferometric microscopes and a scatterometer. We also present the results of application of the experimentally determined MTF correction to the measurement taken with the Micromap{trademark}-570 interferometric microscope of the surface roughness of a super-polished test mirror. In this particular case, without accounting for the instrumental MTF, the surface rms roughness over half of the instrumental spatial frequency bandwidth would be underestimated by a factor of approximately 1.4.

  14. Binary Pseudo-Random Gratings and Arrays for Calibration of Modulation Transfer Functions of Surface Profilometers

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Anderson, Erik D.; Cambie, Rossana; McKinney, Wayne R.; Takacs, Peter Z.; Stover, John C.; Voronov, Dmitriy L.; Yashchuk, Valeriy V.

    2009-09-11

    A technique for precise measurement of the modulation transfer function (MTF), suitable for characterization of a broad class of surface profilometers, is investigated in detail. The technique suggested in [Proc. SPIE 7077-7, (2007), Opt. Eng. 47(7), 073602-1-5 (2008)]is based on use of binary pseudo-random (BPR) gratings and arrays as standard MTF test surfaces. Unlike most conventional test surfaces, BPR gratings and arrays possess white-noise-like inherent power spectral densities (PSD), allowing the direct determination of the one- and two-dimensional MTF, respectively, with a sensitivity uniform over the entire spatial frequency range of a profiler. In the cited work, a one dimensional realization of the suggested method based on use of BPR gratings has been demonstrated. Here, a high-confidence of the MTF calibration technique is demonstrated via cross comparison measurements of a number of two dimensional BPR arrays using two different interferometric microscopes and a scatterometer. We also present the results of application of the experimentally determined MTF correction to the measurement taken with the MicromapTM-570 interferometric microscope of the surface roughness of a super-polished test mirror. In this particular case, without accounting for the instrumental MTF, the surface rms roughness over half of the instrumental spatial frequency bandwidth would be underestimated by a factor of approximately 1.4.

  15. Scattering Analysis of a Compact Dipole Array with Series and Parallel Feed Network including Mutual Coupling Effect

    Directory of Open Access Journals (Sweden)

    H. L. Sneha

    2013-01-01

    Full Text Available The current focus in defense arena is towards the stealth technology with an emphasis to control the radar cross-section (RCS. The scattering from the antennas mounted over the platform is of prime importance especially for a low-observable aerospace vehicle. This paper presents the analysis of the scattering cross section of a uniformly spaced linear dipole array. Two types of feed networks, that is, series and parallel feed networks, are considered. The total RCS of phased array with either kind of feed network is obtained by following the signal as it enters through the aperture and travels through the feed network. The RCS estimation of array is done including the mutual coupling effect between the dipole elements in three configurations, that is, side-by-side, collinear, and parallel-in-echelon. The results presented can be useful while designing a phased array with optimum performance towards low observability.

  16. An LTCC Based Compact SIW Antenna Array Feed Network for a Passive Imaging Radiometer

    KAUST Repository

    Abuzaid, Hattan

    2013-02-05

    Passive millimeter-wave (PMMW) imaging is a technique that allows the detection of inherent millimeter-wave radiation emitted by bodies. Since different bodies with varying properties emit unequal power intensities, a contrast can be established to detect their presence. The advantage of this imaging scheme over other techniques, such as optical and infrared imaging, is its ability to operate under all weather conditions. This is because the relatively long wavelengths of millimeter-waves, as compared to visible light, penetrate through clouds, fog, and sandstorms. The core of a PMMW camera is an antenna, which receives the electromagnetic radiation from a scene. Because PMMW systems require high gains to operate, large antenna arrays are typically employed. This mandatory increase of antenna elements is associated with a large feeding network. Therefore, PMMW cameras usually have a big profile. In this work, two enabling technologies, namely, Substrate integrated Waveguide (SIW) and Low Temperature Co-fired Ceramic (LTCC), are coupled with an innovative design to miniaturize the passive front-end. The two technologies synergize very well with the shielded characteristics of SIW and the high density multilayer integration of LTCC. The proposed design involves a novel multilayer power divider, which is incorporated in a folded feed network structure by moving between layers. The end result is an efficient feeding network, which footprint is least affected by an increase in array size. This is because the addition of more elements is accommodated by a vertical expansion rather than a lateral one. To characterize the feed network, an antenna array has been designed and integrated through efficient transitions.The complete structure has been simulated and fabricated. The results demonstrate an excellent performance, manifesting in a gain of 20 dBi and a bandwidth of more than 11.4% at 35 GHz. These values satisfy the general requirements of a PMMW system.

  17. Calibrating the sensing-coil radius by feed-down from a harmonic reference

    CERN Document Server

    Arpaia, Pasquale; Koster, Oliver; Russenschuck, Stephan; Severino, Giordana

    2015-01-01

    a harmonic field error of higher order is present in the calibration magnet. This also yields a calibration whena sextupole magnet is used, for example, when an insitu calibration is required. The proposed calibration method has been validated by simulations with the

  18. CORPORATE FEED WITH DUAL SEGMENT CIRCULAR POLARIZED ARRAY RECTENNA FOR LOW POWER RF ENERGY HARVESTING

    Directory of Open Access Journals (Sweden)

    CHIA CHAO KANG

    2016-06-01

    Full Text Available This paper focuses on the investigation of the level powers that can be scavenged from the ambient environment by using corporate feed with dual segment circular polarized antenna array . It will converts the received power to direct current (DC. Being a circular polarized antenna, it has higher inductance per unit area, a good Q-factor and compact capability. The design of corporate-series feed rectenna array is to achieve a high gain antenna and maximize the RF energy received by the rectenna system at ultra low power levels. The entire structure was investigated using a combination of harmonic balance nonlinear analysis and full wave electromagnetic field analysis. The results show that 5.0 dBi gain for circular polarized antenna array can be achieved at frequency 956 MHz. When the input power of 20 dBm fed into the transmitting antenna, the maximum distance for radio frequency (RF harvesting is 5.32m. The output DC voltage for various values of incident RF power is also presented. There are noticed reasonable agreements between the simulated and measured result and the works concludes that the investigation of RF energy harvesting system was successful.

  19. Towards a full Atmospheric Calibration system for the Cherenkov Telescope Array

    CERN Document Server

    Doro, M; Blanch, O; Font, LL; Garrido, D; Lopez-Oramas, A

    2013-01-01

    The current generation of Cherenkov telescopes is mainly limited in their gamma-ray energy and flux reconstruction by uncertainties in the determination of atmospheric parameters. The Cherenkov Telescope Array (CTA) aims to provide high-precision data extending the duty cycle as much as possible. To reach this goal, it is necessary to continuously and precisely monitor the atmosphere by means of remote-sensing devices, which are able to provide altitude-resolved and wavelength-dependent extinction factors, sensitive up to the tropopause and higher. Raman LIDARs are currently the best suited technology to achieve this goal with one single instrument. However, the synergy with other instruments like radiometers, solar and stellar photometers, all-sky cameras, and possibly radio-sondes is desirable in order to provide more precise and accurate results, and allows for weather forecasts and now-casts. In this contribution, we will discuss the need and features of such multifaceted atmospheric calibration systems.

  20. Camera calibration strategy of the SST-1M prototype of the Cherenokov Telescope Array

    CERN Document Server

    Prandini, E; Lyard, E.; Schioppa, E. jr.; Neronov, A.; Bilnik, W.; Błocki, J.; Bogacz, L.; Bulik, T.; Cadoux, F.; Christov, A.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Kasperek, J.; Lalik, K.; Mach, E.; Mandat, D.; Marszałek, A.; Michałowski, J.; Moderski, R.; Montaruli, T.; Niemiec, J.; Ostrowski, M.; Paśko, P.; Pech, M.; Porcelli, A.; Rameez, M.; Rajda, P.; Schovanek, P.; Seweryn, K.; Skowron, K.; Sliusar, V.; Sowiński, M.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Toscano, S.; Pujadas, I. Troyano; Walter, R.; Więcek, M.; Zagdański, A.; Ziętara, K.; Żychowski, P.

    2015-01-01

    The SST-1M telescope is one of the prototypes under construction proposed to be part of the future Cherenkov Telescope Array. It uses a standard Davis-Cotton design for the optics and telescope structure, with a dish diameter of 4 meters and a large field-of-view of 9 degrees. The innovative camera design is composed of a photo-detection plane with 1296 pixels including entrance window, light concentrators, Silicon Photomultipliers (SiPMs), and pre-amplifier stages together with a fully digital readout and trigger electronics, DigiCam. In this contribution we give a general description of the analysis chain designed for the SST-1M prototype. In particular we focus on the calibration strategy used to convert the SiPM signals registered by DigiCam to the quantities needed for Cherenkov image analysis. The calibration is based on an online feedback system to stabilize the gain of the SiPMs, as well as dedicated events (dark count, pedestal, and light flasher events) to be taken during the normal operation of the...

  1. A digital combining-weight estimation algorithm for broadband sources with the array feed compensation system

    Science.gov (United States)

    Vilnrotter, V. A.; Rodemich, E. R.

    1994-01-01

    An algorithm for estimating the optimum combining weights for the Ka-band (33.7-GHz) array feed compensation system was developed and analyzed. The input signal is assumed to be broadband radiation of thermal origin, generated by a distant radio source. Currently, seven video converters operating in conjunction with the real-time correlator are used to obtain these weight estimates. The algorithm described here requires only simple operations that can be implemented on a PC-based combining system, greatly reducing the amount of hardware. Therefore, system reliability and portability will be improved.

  2. Higher Order Mode Coupling in Feed Waveguide of a Planar Slot Array Antenna

    Science.gov (United States)

    Rengarajan, Sembiam

    2011-01-01

    A simple technique was developed to account for the higher order mode coupling between adjacent coupling slots in the feed waveguide of a planar slot array. The method uses an equation relating the slot impedance to the slot voltage and a reaction integral involving the equivalent magnetic current of the slot aperture and the magnetic field coupled from an adjacent slot. In the proposed method, one uses the Elliott s design technique to determine tilt angles and lengths of the coupling slots. The radiating slots are modeled as shunt admittances, and the coupling slots are modeled as series impedances.

  3. Neutrino detection, position calibration and marine science with acoustic arrays in the deep sea

    Energy Technology Data Exchange (ETDEWEB)

    Lahmann, R., E-mail: robert.lahmann@physik.uni-erlangen.de [Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany)

    2013-10-11

    Arrays of acoustic receivers are an integral part of present and potential future Cherenkov neutrino telescopes in the deep sea. They measure the positions of individual detector elements which vary with time as an effect of undersea currents. At the same time, the acoustic receivers can be employed for marine science purposes, in particular for monitoring the ambient noise environment and the signals emitted by the fauna of the sea. And last but not least, they can be used for studies towards acoustic detection of ultra-high-energy neutrinos. Measuring acoustic pressure pulses in huge underwater acoustic arrays with an instrumented volume of the order of 100 km{sup 3} is a promising approach for the detection of cosmic neutrinos with energies exceeding 1 EeV. Pressure signals are produced by the particle cascades that evolve when neutrinos interact with nuclei in water, and can be detected over large distances in the kilometre range. In this article, the status of acoustic detection will be reviewed and plans for the future – most notably in the context of KM3NeT – will be discussed. The connection between neutrino detection, position calibration and marine science will be illustrated.

  4. Characterization and calibration of compact array spectrometers in the ultraviolet spectral region

    International Nuclear Information System (INIS)

    Array-based spectrometers, with their compact size, low weight, low cost, and fast measurement time, are now frequently used in place of both conventional single-channel scanning monochromators, and broadband meters. Their rapid measurement capability makes them an attractive option for routine solar UV spectral measurements, where shortterm variability in signal is a challenge. However, compactness, portability, low cost and high speed are achieved at the expense of the spectrometer's optical and electronic performance. Thus such spectrometers are more prone to measurement error from environmental changes, and more prone to other intrinsic sources of error such as stray light and detector non-linearity, which significantly affect solar UV measurements, than a scanning monochromator. The effects of stray light and non-linearity can be reduced either by improved optical and detector design or by a detailed spectrometer characterization. We present in this paper our investigation of the performance of three different commercial array spectrometers: two mini-spectrometers, and a more elaborate array spectrometer with an on-board image amplifier device. These were tested for a subset of performance parameters: their wavelength accuracy and stability, electronic linearity, responsivity linearity, stray light sensitivity, and mechanical stability and repeatability. With all three spectrometers we found that these parameters, particularly but not limited to stray light, had a significant impact on the measurement of the incoming optical radiation. This meant that, without characterization, the instruments would be unable to accurately measure the UV component of any source with significant visible radiation. We discuss various simple and low-cost solutions for improving the performance of these instruments, and providing a rigorous calibration using a straightforward set-up including optical filters and the quasi-monochromatic light from a double monochromator.

  5. Deployable reflector antenna performance optimization using automated surface correction and array-feed compensation

    Science.gov (United States)

    Schroeder, Lyle C.; Bailey, M. C.; Mitchell, John L.

    1992-01-01

    Methods for increasing the electromagnetic (EM) performance of reflectors with rough surfaces were tested and evaluated. First, one quadrant of the 15-meter hoop-column antenna was retrofitted with computer-driven and controlled motors to allow automated adjustment of the reflector surface. The surface errors, measured with metric photogrammetry, were used in a previously verified computer code to calculate control motor adjustments. With this system, a rough antenna surface (rms of approximately 0.180 inch) was corrected in two iterations to approximately the structural surface smoothness limit of 0.060 inch rms. The antenna pattern and gain improved significantly as a result of these surface adjustments. The EM performance was evaluated with a computer program for distorted reflector antennas which had been previously verified with experimental data. Next, the effects of the surface distortions were compensated for in computer simulations by superimposing excitation from an array feed to maximize antenna performance relative to an undistorted reflector. Results showed that a 61-element array could produce EM performance improvements equal to surface adjustments. When both mechanical surface adjustment and feed compensation techniques were applied, the equivalent operating frequency increased from approximately 6 to 18 GHz.

  6. A Tutorial on Optical Feeding of Millimeter-Wave Phased Array Antennas for Communication Applications

    Directory of Open Access Journals (Sweden)

    Ivan Aldaya

    2015-01-01

    Full Text Available Given the interference avoidance capacity, high gain, and dynamical reconfigurability, phased array antennas (PAAs have emerged as a key enabling technology for future broadband mobile applications. This is especially important at millimeter-wave (mm-wave frequencies, where the high power consumption and significant path loss impose serious range constraints. However, at mm-wave frequencies the phase and amplitude control of the feeding currents of the PAA elements is not a trivial issue because electrical beamforming requires bulky devices and exhibits relatively narrow bandwidth. In order to overcome these limitations, different optical beamforming architectures have been presented. In this paper we review the basic principles of phased arrays and identify the main challenges, that is, integration of high-speed photodetectors with antenna elements and the efficient optical control of both amplitude and phase of the feeding current. After presenting the most important solutions found in the literature, we analyze the impact of the different noise sources on the PAA performance, giving some guidelines for the design of optically fed PAAs.

  7. NORSAR Final Scientific Report Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Gibbons, S J; Ringdal, F; Harris, D B

    2009-04-16

    detectors. To meet this challenge, we have examined two strategies: (1) use of subspace detectors, a multi-dimensional extension of correlators, which allow representation and detection of signals exhibiting some degree of variation; and (2) autonomous calibration of many subspace and correlation detectors in an adaptive detection framework, subject to analyst review. Because correlation detectors are relatively new to seismology, a significant amount of research on how to tune these detectors has been needed to address later calibration efforts that will arise as they are adopted for operational use. We have approached these challenges by carrying out a number of case studies, encompassing various monitoring scenarios such as earthquake aftershock sequences and swarms, recurring mining explosions, other types of explosions, and rockbursts. We have studied several different geographical regions (the European Arctic, Central Asia, and the western United States). We have drawn on available Ground Truth data in assessing the results of the various processing schemes. In all cases, we have benefited from the high-quality seismic arrays or networks available in these regions, and we have thus been able to evaluate the performance of array-based correlation processing under a variety of conditions. The main results of the project are summarized as follows: (1) Array-based waveform correlation has been demonstrated to lower significantly detection thresholds in comparison with standard single-channel waveform correlation. (2) Frequency-wavenumber analysis of the correlation traces on a small-aperture array provides an effective method for screening out a certain category of false alarms, and can therefore be used to improve detector sensitivity by lowering the threshold for automatic array detection. (3) We have developed and tested a framework for autonomous correlation detection. The framework comprises a set of conventional (STA/LTA) detectors on a collection of array beams

  8. Single-feed superconducting circularly polarized microstrip array antenna for direct-to-home receiving system

    Energy Technology Data Exchange (ETDEWEB)

    Ali, M.I.; Ehata, K.; Ohshima, S. [Faculty of Engineering, Yamagata University, Jonan 4-3-16, Yonezawa 992-8510 (Japan)

    2000-07-01

    Single-feed circularly polarized microstrip patch and patch array antennas for 'direct-to-home' receiving system at around 12 GHz are studied by theoretical analysis and experiments. A full-wave microwave circuit simulator (Em), based on the method of moments and capable of handling the microwave surface impedance, has been used in the theoretical analysis of the antennas. Antennas have been fabricated from both normal conductor (gold) and YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) superconductor for comparison. Measured results on resonant frequency (f{sub r}), return loss, gain, bandwidth, and axial ratio are presented. The antennas are found to show a very low axial ratio and a moderate bandwidth. In the comparison of gain, the superconducting antennas showed a remarkable improvement over their gold counterparts. The receiving power of a four-element array fabricated from a single-side YBCO thin film on (100) MgO single crystal substrate is found to be 1.8 dB higher than that of a gold array with identical configuration and both measured at 77 K. (author)

  9. Radar cross section of dipole phased arrays with parallel feed network

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents the detailed analytical formulation for the RCS of parallel-fed linear dipole array in the presence of mutual coupling. The radar cross section (RCS) of an object represents its electromagnetic (EM) scattering properties for a given incident wave. The analysis of scattered field is critical in military and defence arenas, especially while designing low-observable platforms. It is well-known that the presence of an antenna/array on the target influences its echo area significantly. The primary cause for such scattering of the incident signals is reflection that occurs within the antenna aperture and its feed network. In this book, the RCS estimation is done based on the signal path within the antenna system. The scattered field is expressed in terms of array design parameters including the reflection and transmission coefficients. The computed results show the variation in the RCS pattern with and without mutual coupling. The effect of finite dipole-length, inter-element spacing, scan angle,...

  10. Color Calibration for Colorized Vision System with Digital Sensor and LED Array Illuminator

    Directory of Open Access Journals (Sweden)

    Zhenmin Zhu

    2016-01-01

    Full Text Available Color measurement by the colorized vision system is a superior method to achieve the evaluation of color objectively and continuously. However, the accuracy of color measurement is influenced by the spectral responses of digital sensor and the spectral mismatch of illumination. In this paper, two-color vision system illuminated by digital sensor and LED array, respectively, is presented. The Polynomial-Based Regression method is applied to solve the problem of color calibration in the sRGB and CIE  L⁎a⁎b⁎ color spaces. By mapping the tristimulus values from RGB to sRGB color space, color difference between the estimated values and the reference values is less than 3ΔE. Additionally, the mapping matrix ΦRGB→sRGB has proved a better performance in reducing the color difference, and it is introduced subsequently into the colorized vision system proposed for a better color measurement. Necessarily, the printed matter of clothes and the colored ceramic tile are chosen as the application experiment samples of our colorized vision system. As shown in the experimental data, the average color difference of images is less than 6ΔE. It indicates that a better performance of color measurement is obtained via the colorized vision system proposed.

  11. Development and Calibration of a Field-Deployable Microphone Phased Array for Propulsion and Airframe Noise Flyover Measurements

    Science.gov (United States)

    Humphreys, William M., Jr.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.; Ravetta, Patricio A.; Johns, Zachary

    2016-01-01

    A new aeroacoustic measurement capability has been developed consisting of a large channelcount, field-deployable microphone phased array suitable for airframe noise flyover measurements for a range of aircraft types and scales. The array incorporates up to 185 hardened, weather-resistant sensors suitable for outdoor use. A custom 4-mA current loop receiver circuit with temperature compensation was developed to power the sensors over extended cable lengths with minimal degradation of the signal to noise ratio and frequency response. Extensive laboratory calibrations and environmental testing of the sensors were conducted to verify the design's performance specifications. A compact data system combining sensor power, signal conditioning, and digitization was assembled for use with the array. Complementing the data system is a robust analysis system capable of near real-time presentation of beamformed and deconvolved contour plots and integrated spectra obtained from array data acquired during flyover passes. Additional instrumentation systems needed to process the array data were also assembled. These include a commercial weather station and a video monitoring / recording system. A detailed mock-up of the instrumentation suite (phased array, weather station, and data processor) was performed in the NASA Langley Acoustic Development Laboratory to vet the system performance. The first deployment of the system occurred at Finnegan Airfield at Fort A.P. Hill where the array was utilized to measure the vehicle noise from a number of sUAS (small Unmanned Aerial System) aircraft. A unique in-situ calibration method for the array microphones using a hovering aerial sound source was attempted for the first time during the deployment.

  12. Vortex arrays and ciliary tangles underlie the feeding-swimming tradeoff in starfish larvae

    CERN Document Server

    Gilpin, William; Prakash, Manu

    2016-01-01

    Many marine invertebrates have larval stages covered in linear arrays of beating cilia, which propel the animal while simultaneously entraining planktonic prey. These bands are strongly conserved across taxa spanning four major superphyla, and they are responsible for the unusual morphologies of many invertebrates. However, few studies have investigated their underlying hydrodynamics. Here, we study the ciliary bands of starfish larvae, and discover a beautiful pattern of slowly-evolving vortices that surrounds the swimming animals. Closer inspection of the bands reveals unusual ciliary "tangles" analogous to topological defects that break-up and re-form as the animal adjusts its swimming stroke. Quantitative experiments and modeling suggest that these vortices create a physical tradeoff between feeding and swimming, which manifests as distinct flow patterns or "eigenstrokes" representing each behavior---potentially implicating neuronal control of cilia. This quantitative interplay between larval form and hyd...

  13. Testing a modified ASKAP Mark II phased array feed on the 64 m Parkes radio telescope

    CERN Document Server

    Chippendale, A P; Deng, X; Leach, M; Reynolds, J E; Kramer, M; Tzioumis, T

    2016-01-01

    We present the first installation and characterization of a phased array feed (PAF) on the 64 m Parkes radio telescope. The combined system operates best between 0.8 GHz and 1.74 GHz where the beamformed noise temperature is between 45 K and 60 K, the aperture efficiency ranges from 70% to 80%, and the effective field of view is 1.4 deg$^2$ at 1310 MHz. After a 6-month trial observing program at Parkes, the PAF will be installed on the 100 m antenna at Effelsberg. This is the first time a PAF has been installed on a large single-antenna radio telescope and made available to astronomers.

  14. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging

    OpenAIRE

    Pang, Yong; Yu, Baiying; Daniel B Vigneron; Zhang, Xiaoliang

    2014-01-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional ...

  15. An active reference spring array for in-situ calibration of the normal spring constant of AFM cantilevers

    Science.gov (United States)

    Gao, S.; Brand, U.; Hahn, S.; Hiller, K.

    2015-05-01

    In this paper the concept of an "active reference spring array (ARSA)" for the AFM cantilever normal spring constant calibration is proposed. The ARSA with nominal stiffness varying from 0.4 N/m to 150 N/m will be available on these arrays with the aim to calibrate the normal stiffness of cantilevers ranging from 0.04 N/m to 1500 N/m. The fabrication process of the MEMS ARSA on basis of the Bonding Deep RIE technology developed at Chemnitz University of Technology is reported. A first characterization of the MEMS and the traceable determination of the stiffness of the MEMS suspending system have been realized. First experimental results compare very well with the Finite Element (FE) simulation of the numerical design, and prove the feasibility of the proposed concept.

  16. Recent advances in image reconstruction, coil sensitivity calibration, and coil array design for SMASH and generalized parallel MRI.

    Science.gov (United States)

    Sodickson, Daniel K; McKenzie, Charles A; Ohliger, Michael A; Yeh, Ernest N; Price, Mark D

    2002-01-01

    Parallel magnetic resonance imaging (MRI) techniques use spatial information from arrays of radiofrequency (RF) detector coils to accelerate imaging. A number of parallel MRI techniques have been described in recent years, and numerous clinical applications are currently being explored. The advent of practical parallel imaging presents various challenges for image reconstruction and RF system design. Recent advances in tailored SiMultaneous Acquisition of Spatial Harmonics (SMASH) image reconstructions are summarized. These advances enable robust SMASH imaging in arbitrary image planes with a wide range of coil array geometries. A generalized formalism is described which may be used to understand the relations between SMASH and SENSE, to derive typical implementations of each as special cases, and to form hybrid techniques combining some of the advantages of both. Accurate knowledge of coil sensitivities is crucial for parallel MRI, and errors in calibration represent one of the most common and the most pernicious sources of error in parallel image reconstructions. As one example, motion of the patient and/or the coil array between the sensitivity reference scan and the accelerated acquisition can lead to calibration errors and reconstruction artifacts. Self-calibrating parallel MRI approaches that address this problem by eliminating the need for external sensitivity references are reviewed. The ultimate achievable signal-to-noise ratio (SNR) for parallel MRI studies is closely tied to the geometry and sensitivity patterns of the coil arrays used for spatial encoding. Several parallel imaging array designs that depart from the traditional model of overlapped adjacent loop elements are described. PMID:11755091

  17. An L-Band, Circularly Polarised, Dual-Feed, Cavity-Backed Annular Slot Antenna For Phased-Array Applications

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2006-01-01

    The results of a parametric study for the development of an L-band, circularly polarised, dual-feed, cavity-backed annular slot antenna is presented. The study included detailed numerical simulations and measurements on a prototype with different ground planes, to assess the antenna’s applicability...... as an element in a small phased array antenna....

  18. SweepSAR: Beam-forming on Receive Using a Reflector-Phased Array Feed Combination for Spaceborne SAR

    Science.gov (United States)

    Freeman, A.; Krieger, G.; Rosen, P.; Younis, M.; Johnson, W. T. K.; Huber, S.; Jordan, R.; Moreira, A.

    2012-01-01

    In this paper, an alternative approach is described that is suited for longer wavelength SARs in particular, employing a large, deployable reflector antenna and a much simpler phased array feed. To illuminate a wide swath, a substantial fraction of the phased array feed is excited on transmit to sub-illuminate the reflector. Shorter transmit pulses are required than for conventional SAR. On receive, a much smaller portion of the phased array feed is used to collect the return echo, so that a greater portion of the reflector antenna area is used. The locus of the portion of the phased array used on receive is adjusted using an analog beam steering network, to 'sweep' the receive beam(s) across the illuminated swath, tracking the return echo. This is similar in some respects to the whiskbroom approach to optical sensors, hence the name: SweepSAR.SweepSAR has advantages over conventional SAR in that it requires less transmit power, and if the receive beam is narrow enough, it is relatively immune to range ambiguities. Compared to direct radiating arrays with digital beam- forming, it is much simpler to implement, uses currently available technologies, is better suited for longer wavelength systems, and does not require extremely high data rates or onboard processing.

  19. Multi-Array Back-Projections of The 2015 Gorkha Earthquake With Physics-Based Aftershock Calibrations

    Science.gov (United States)

    Meng, L.; Zhang, A.; Yagi, Y.

    2015-12-01

    The 2015 Mw 7.8 Nepal-Gorkha earthquake with casualties of over 9,000 people is the most devastating disaster to strike Nepal since the 1934 Nepal-Bihar earthquake. Its rupture process is well imaged by the teleseismic MUSIC back-projections (BP). Here, we perform independent back-projections of high-frequency recordings (0.5-2 Hz) from the Australian seismic network (AU), the North America network (NA) and the European seismic network (EU), located in complementary orientations. Our results of all three arrays show unilateral linear rupture path to the east of the hypocenter. But the propagating directions and the inferred rupture speeds differ significantly among different arrays. To understand the spatial uncertainties of the BP analysis, we image four moderate-size (M5~6) aftershocks based on the timing correction derived from the alignment of the initial P-wave of the mainshock. We find that the apparent source locations inferred from BP are systematically biased along the source-array orientation, which can be explained by the uncertainty of the 3D velocity structure deviated from the 1D reference model (e.g. IASP91). We introduced a slowness error term in travel time as a first-order calibration that successfully mitigates the source location discrepancies of different arrays. The calibrated BP results of three arrays are mutually consistent and reveal a unilateral rupture propagating eastward at a speed of 2.7 km/s along the down-dip edge of the locked Himalaya thrust zone over ~ 150 km, in agreement with a narrow slip distribution inferred from finite source inversions.

  20. Amplitude, phase, location and orientation calibration of an acoustic vector sensor array, part I: Theory

    NARCIS (Netherlands)

    Xu, B.; Wind, J.; Bree, H.E. de; Basten, T.G.H.; Druyvesteyn, E.

    2010-01-01

    An acoustic vector sensor array consists of multiple sound pressure microphones and particle velocity sensors. A pressure microphone usually has an omni-directional response, yet a particle velocity sensor is directional. Currently, acoustic vector sensor arrays are under investigation for far field

  1. General Matrix Inversion Technique for the Calibration of Electric Field Sensor Arrays on Aircraft Platforms

    Science.gov (United States)

    Mach, D. M.; Koshak, W. J.

    2007-01-01

    A matrix calibration procedure has been developed that uniquely relates the electric fields measured at the aircraft with the external vector electric field and net aircraft charge. The calibration method can be generalized to any reasonable combination of electric field measurements and aircraft. A calibration matrix is determined for each aircraft that represents the individual instrument responses to the external electric field. The aircraft geometry and configuration of field mills (FMs) uniquely define the matrix. The matrix can then be inverted to determine the external electric field and net aircraft charge from the FM outputs. A distinct advantage of the method is that if one or more FMs need to be eliminated or deemphasized [e.g., due to a malfunction), it is a simple matter to reinvert the matrix without the malfunctioning FMs. To demonstrate the calibration technique, data are presented from several aircraft programs (ER-2, DC-8, Altus, and Citation).

  2. A robust and passive method for geometric calibration of large arrays

    CERN Document Server

    Vanwynsberghe, Charles; Marchal, Jacques; Marchiano, Régis; Ollivier, François

    2016-01-01

    This paper presents a complete strategy for the geometry estimation of large microphone arrays of arbitrary shape. Largeness is intended here in both number of microphones (hundreds) and size (few meters). Such arrays can be used for various applications in open or confined spaces like acoustical imaging, source identification, or speech processing. For so large array systems,measuring the geometry by hand is impractical. Therefore a blind passive method is proposed. It is based on the analysis of the background acoustic noise, supposed to be a diffuse field. The proposed strategy is a two-step process. First the pairwise microphone distances are identified by matching their measured coherence function to the one predicted by the diffuse field theory. Second, a robust multidimensional scaling(MDS) algorithm is adapted and implemented. It takes advantage of local characteristics to reduce the set of distances and infer the geometry of the array. This work is an extension of previous studies, and it overcomes u...

  3. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging.

    Science.gov (United States)

    Pang, Yong; Yu, Baiying; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-02-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than -35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla. PMID:24649430

  4. MeerKAT - The South African Array With Composite Dishes and Wide-Band Single Pixel Feeds

    Science.gov (United States)

    Jonas, J. L.

    2009-08-01

    The MeerKAT is a precursor for the "small dish plus single-pixel wide-band feed" scenario for the Square Kilometre Array (SKA). The current goal specification is for an array of 80 12-m dishes operating over a continuous frequency range of 0.7-10 GHz, thus the individual receptors match the SKA draft specification for midband dishes. The proposed array configuration is centrally concentrated with 70% of the collecting area within a 700-m-diameter circle and the remaining 30% extending out to baselines of 10 km. The site for MeerKAT lies within a radio quiet reserve established in the remote and Northern Cape province of South Africa. The technologies and techniques that MeerKAT will develop and evaluate include wide-bandwidth feeds, low-cost dish antennas, instrumentation for high dynamic range observations, packet-switched array processing architectures, shielding of component radio-frequency interference (RFI), mitigation of external RFI, and low-cost and reliable remote telescope operation.

  5. A computer program for calculating relative-transmissivity input arrays to aid model calibration

    Science.gov (United States)

    Weiss, Emanuel

    1982-01-01

    A program is documented that calculates a transmissivity distribution for input to a digital ground-water flow model. Factors that are taken into account in the calculation are: aquifer thickness, ground-water viscosity and its dependence on temperature and dissolved solids, and permeability and its dependence on overburden pressure. Other factors affecting ground-water flow are indicated. With small changes in the program code, leakance also could be calculated. The purpose of these calculations is to provide a physical basis for efficient calibration, and to extend rational transmissivity trends into areas where model calibration is insensitive to transmissivity values.

  6. Binary pseudo-random gratings and arrays for calibration of the modulation transfer function of surface profilometers: recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Soldate, Paul; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wanye R.; Takacs, Peter Z.; Voronov, Dmitry L.; Yashchuk, Valeriy V.

    2009-07-07

    The major problem of measurement of a power spectral density (PSD) distribution of the surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments. The MTF tends to distort the PSD at higher spatial frequencies. It has been suggested [Proc. SPIE 7077-7, (2007), Opt. Eng. 47 (7), 073602-1-5 (2008)] that the instrumental MTF of a surface profiler can be precisely measured using standard test surfaces based on binary pseudo-random (BPR) patterns. In the cited work, a one dimensional (1D) realization of the suggested method based on use of BPR gratings has been demonstrated. Here, we present recent achievements made in fabricating and using two-dimensional (2D) BPR arrays that allow for a direct 2D calibration of the instrumental MTF. The 2D BPRAs were used as standard test surfaces for 2D MTF calibration of the MicromapTM-570 interferometric microscope with all available objectives. The effects of fabrication imperfections on the efficiency of calibration are also discussed.

  7. Amplitude, phase, location and orientation calibration of an acoustic vector sensor array, part II: Experiments

    NARCIS (Netherlands)

    Basten, T.G.H.; Wind, J.; Xu, B.; Bree, H.E. de; Druyvesteyn, E.

    2010-01-01

    An acoustic vector sensor array consists of multiple sound pressure microphones and particle velocity sensors. A pressure microphone usually has an omni-directional response, yet a particle velocity sensor is directional and usually has a response pattern as a figure of eight. Currently, acoustic ve

  8. Efficiency calibration and coincidence summing correction for large arrays of NaI(Tl) detectors in soccer-ball and castle geometries

    Energy Technology Data Exchange (ETDEWEB)

    Anil Kumar, G., E-mail: anilg@tifr.res.i [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Mazumdar, I.; Gothe, D.A. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)

    2009-11-21

    Efficiency calibration and coincidence summing correction have been performed for two large arrays of NaI(Tl) detectors in two different configurations. They are, a compact array of 32 conical detectors of pentagonal and hexagonal shapes in soccer-ball geometry and an array of 14 straight hexagonal NaI(Tl) detectors in castle geometry. Both of these arrays provide a large solid angle of detection, leading to considerable coincidence summing of gamma rays. The present work aims to understand the effect of coincidence summing of gamma rays while determining the energy dependence of efficiencies of these two arrays. We have carried out extensive GEANT4 simulations with radio-nuclides that decay with a two-step cascade, considering both arrays in their realistic geometries. The absolute efficiencies have been simulated for gamma energies from 700 to 2800 keV using four different double-photon emitters, namely, {sup 60}Co, {sup 46}Sc, {sup 94}Nb and {sup 24}Na. The efficiencies so obtained have been corrected for coincidence summing using the method proposed by Vidmar et al. . The simulations have also been carried out for the same energies assuming mono-energetic point sources, for comparison. Experimental measurements have also been carried out using calibrated point sources of {sup 137}Cs and {sup 60}Co. The simulated and the experimental results are found to be in good agreement. This demonstrates the reliability of the correction method for efficiency calibration of two large arrays in very different configurations.

  9. An initial analysis of options for a UK feed-in tariff for photovoltaic energy, from an array owner's viewpoint

    Science.gov (United States)

    Plater, Steve

    2009-10-01

    The UK government has announced the introduction from April 2010 of a feed-in tariff (FIT) for renewable energy, and initiated a consultation on its design. This paper compares three possible variants of a UK FIT for rooftop photovoltaic (PV) arrays, on the basis of calculated income and array cost payback time, and for three locations (north, central and southern England) and various levels of household electricity consumption. This modelling is based on an FIT rate equivalent to Germany's. It concludes that an FIT which paid only for PV electricity surplus to on-site needs, and exported to the grid, would mean a simple payback time too long to make array purchase appealing. Preferable would be either export to the grid of all PV electricity for FIT payment; or a lower FIT rate for electricity used on-site, plus full FIT for any surplus exported. The latter would involve significantly lower costs in feed-in tariff payments. Finally, the effect of the UK government's illustrative FIT rate for consultation is examined for the same locations and annual consumption levels.

  10. 传声器阵列校准技术研究%Calibration technology of microphone array

    Institute of Scientific and Technical Information of China (English)

    李元首; 陈宝; 张雪; 姜涛

    2014-01-01

    Aerodynamic noise is usually broadband noise. The designed array needs to satisfy the measurement require⁃ments of both high and low frequency signals. The corresponding array form is designed when the frequency range of array mea⁃surement is determined. The noise source localization technology based on microphone array is the core test technique in the wind tunnel aerodynamic noise test technology. The accuracy of noise source localization depends mainly on the microphone ar⁃ray calibration technique. After the microphone phase array is installed,different frequency response and sensitivity,preamplifier, cable laying,power supply,frequency response of signal conditioner and the installation of microphone array can cause the phase difference and amplitude difference among all measurement channels in the data acquisition system. Correction of phase difference and amplitude difference of microphones can make all the microphone frequency responses consistent and ensure the accuracy of test result.%气动噪声通常为宽频噪声,设计的阵列需要同时满足对高低频信号的测量需求,在确定了阵列测量频率范围的情况下,设计相应的阵列形式。在风洞气动噪声试验技术中,基于传声器阵列的噪声源定位技术是核心试验技术,噪声源定位的精准度主要取决于传声器阵列校准技术。传声器相位阵列安装之后,由于传声器频率响应和灵敏度不同,前置放大器、电缆的铺设、电源和信号调理器的频率响应以及传声器在阵列中的安装影响,会引起数据采集系统各测量通道间固有的相位差和幅值差。修正传声器的相位差和幅值差使得所有的传声器幅频响应一致,保证试验结果的准度。

  11. Calibration scheme for large Kinetic Inductance Detector Arrays based on Readout Frequency Response

    OpenAIRE

    Bisigello, L.; Yates, S J C; Murugesan, V.; Baselmans, J. J. A.; Baryshev, A. M.

    2016-01-01

    Microwave kinetic inductance detector (MKID) provides a way to build large ground based sub-mm instruments such as NIKA and A-MKID. For such instruments, therefore, it is important to understand and characterize the response to ensure good linearity and calibration over wide dynamic range. We propose to use the MKID readout frequency response to determine the MKID responsivity to an input optical source power. A signal can be measured in a KID as a change in the phase of the readout signal wi...

  12. Performance analysis for time-frequency MUSIC algorithm in presence of both additive noise and array calibration errors

    Science.gov (United States)

    Khodja, Mohamed; Belouchrani, Adel; Abed-Meraim, Karim

    2012-12-01

    This article deals with the application of Spatial Time-Frequency Distribution (STFD) to the direction finding problem using the Multiple Signal Classification (MUSIC)algorithm. A comparative performance analysis is performed for the method under consideration with respect to that using data covariance matrix when the received array signals are subject to calibration errors in a non-stationary environment. An unified analytical expression of the Direction Of Arrival (DOA) error estimation is derived for both methods. Numerical results show the effect of the parameters intervening in the derived expression on the algorithm performance. It is particularly observed that for low Signal to Noise Ratio (SNR) and high Signal to sensor Perturbation Ratio (SPR) the STFD method gives better performance, while for high SNR and for the same SPR both methods give similar performance.

  13. Calibration scheme for large Kinetic Inductance Detector Arrays based on Readout Frequency Response

    CERN Document Server

    Bisigello, L; Murugesan, V; Baselmans, J J A; Baryshev, A M

    2016-01-01

    Microwave kinetic inductance detector (MKID) provides a way to build large ground based sub-mm instruments such as NIKA and A-MKID. For such instruments, therefore, it is important to understand and characterize the response to ensure good linearity and calibration over wide dynamic range. We propose to use the MKID readout frequency response to determine the MKID responsivity to an input optical source power. A signal can be measured in a KID as a change in the phase of the readout signal with respect to the KID resonant circle. Fundamentally, this phase change is due to a shift in the KID resonance frequency, in turn due to a radiation induced change in the quasiparticle number in the superconducting resonator. We show that shift in resonant frequency can be determined from the phase shift by using KID phase versus frequency dependence using a previously measured resonant frequency. Working in this calculated resonant frequency, we gain near linearity and constant calibration to a constant optical signal ap...

  14. Corporate-Feed Multilayer Bow-Tie Antenna Array Design Using a Simple Transmission Line Model

    OpenAIRE

    Didouh, S.; Abri, M.; F. T. Bendimerad

    2012-01-01

    A transmission line model is used to design corporate-fed multilayered bow-tie antennas arrays; the simulated antennas arrays are designed to resonate at the frequencies 2.4 GHz, 5 GHz, and 8 GHz corresponding to RFID, WIFI, and radars applications. The contribution of this paper consists of modeling multilayer bow-tie antenna array fed through an aperture using transmission line model. The transmission line model is simple and precise and allows taking into account the whole geometrical, ele...

  15. Neutrino Detection, Position Calibration and Marine Science with Acoustic Arrays in the Deep Sea

    CERN Document Server

    Lahmann, Robert

    2013-01-01

    Arrays of acoustic receivers are an integral part of present and potential future Cherenkov neutrino telescopes in the deep sea. They measure the positions of individual detector elements which vary with time as an effect of undersea currents. At the same time, the acoustic receivers can be employed for marine science purposes, in particular for monitoring the ambient noise environment and the signals emitted by the fauna of the sea. And last but not least, they can be used for studies towards acoustic detection of ultra-high-energy neutrinos. Measuring acoustic pressure pulses in huge underwater acoustic arrays with an instrumented volume of the order of 100 km^3 is a promising approach for the detection of cosmic neutrinos with energies exceeding 1 EeV. Pressure signals are produced by the particle cascades that evolve when neutrinos interact with nuclei in water, and can be detected over large distances in the kilometre range. In this article, the status of acoustic detection will be reviewed and plans for...

  16. Calibrating a novel type of bolometer arrays for the Herschel/PACS Photometer

    CERN Document Server

    Billot, Nicolas

    2008-01-01

    The Herschel Space Observatory is a corner stone mission of the European Space Agency (ESA) scientific program. With its spatial resolution, sensitivity and spectral range (60 to 670 microns) Herschel will provide astronomers with unique opportunities to decipher many aspects of star formation mecanisms and galaxy evolution. Among the many research institutes involved in the development and exploitation of this challenging observatory, the Commissariat a l'Energie Atomique (CEA) designed a novel type of bolometric detectors to equip the photometer of the PACS instrument on-board the Herschel satellite. In this thesis, I present the basics of infrared astronomy and past and present developments in cryogenic bolometers, emphasising on new concepts introduced by CEA, that is the collective manufacturing of bolometer arrays, the high impedance thermometers, the cold multiplexing and the use of a resonant cavity to optimize absorption of electromagnetic radiation. I follow with an in-depth explanation of the worki...

  17. Rapid determination of lidocaine solutions with non-column chromatographic diode array UV spectroscopy and multivariate calibration.

    Science.gov (United States)

    Wiberg, Kent; Hagman, Anders; Jacobsson, Sven P

    2003-01-01

    A new method for the rapid determination of pharmaceutical solutions is proposed. A conventional HPLC system with a Diode Array Detector (DAD) was used with no chromatographic column connected. As eluent, purified water (Milli Q) was used. The pump and autosampler of the HPLC system were mainly utilised as an automatic and convenient way of introducing the sample into the DAD. The method was tested on the local anaesthetic compound lidocaine. The UV spectrum (245-290 nm) from the samples analysed in the detector was used for multivariate calibration for the determination of lidocaine solutions. The content was determined with PLS regression. The effect on the predictive ability of three factors: flow, data-collection rate and rise time as well as two ways of exporting a representative UV spectrum from the DAD file collected was investigated by means of an experimental design comprising 11 experiments. For each experiment, 14 solutions containing a known content of lidocaine were analysed (0.02-0.2 mg ml(-1)). From these 14 samples two calibration sets and two test sets were made and as the response in the experimental design the Root Mean Square Error of Prediction (RMSEP) values from the predictions of the two test sets were used. When the factor setting giving the lowest RMSEP was found, this setting was used when analysing a new calibration set of 12 lidocaine samples (0.1-0.2 mg ml(-1)). This calibration model was validated by two external test sets, A and B, analysed on separate occasions for the evaluation of repeatability (test set A) and determination over time (test set B). For comparison, the reference method, liquid chromatography, was also used for analysis of the ten samples in test set B. This comparison of the two methods was done twice on different occasions. The results show that in respect of accuracy, precision and repeatability the new method is comparable to the reference method. The main advantages compared with liquid chromatography are the

  18. Rapid determination of lidocaine solutions with non-column chromatographic diode array UV spectroscopy and multivariate calibration.

    Science.gov (United States)

    Wiberg, Kent; Hagman, Anders; Jacobsson, Sven P

    2003-01-01

    A new method for the rapid determination of pharmaceutical solutions is proposed. A conventional HPLC system with a Diode Array Detector (DAD) was used with no chromatographic column connected. As eluent, purified water (Milli Q) was used. The pump and autosampler of the HPLC system were mainly utilised as an automatic and convenient way of introducing the sample into the DAD. The method was tested on the local anaesthetic compound lidocaine. The UV spectrum (245-290 nm) from the samples analysed in the detector was used for multivariate calibration for the determination of lidocaine solutions. The content was determined with PLS regression. The effect on the predictive ability of three factors: flow, data-collection rate and rise time as well as two ways of exporting a representative UV spectrum from the DAD file collected was investigated by means of an experimental design comprising 11 experiments. For each experiment, 14 solutions containing a known content of lidocaine were analysed (0.02-0.2 mg ml(-1)). From these 14 samples two calibration sets and two test sets were made and as the response in the experimental design the Root Mean Square Error of Prediction (RMSEP) values from the predictions of the two test sets were used. When the factor setting giving the lowest RMSEP was found, this setting was used when analysing a new calibration set of 12 lidocaine samples (0.1-0.2 mg ml(-1)). This calibration model was validated by two external test sets, A and B, analysed on separate occasions for the evaluation of repeatability (test set A) and determination over time (test set B). For comparison, the reference method, liquid chromatography, was also used for analysis of the ten samples in test set B. This comparison of the two methods was done twice on different occasions. The results show that in respect of accuracy, precision and repeatability the new method is comparable to the reference method. The main advantages compared with liquid chromatography are the

  19. Corporate-Feed Multilayer Bow-Tie Antenna Array Design Using a Simple Transmission Line Model

    Directory of Open Access Journals (Sweden)

    S. Didouh

    2012-01-01

    Full Text Available A transmission line model is used to design corporate-fed multilayered bow-tie antennas arrays; the simulated antennas arrays are designed to resonate at the frequencies 2.4 GHz, 5 GHz, and 8 GHz corresponding to RFID, WIFI, and radars applications. The contribution of this paper consists of modeling multilayer bow-tie antenna array fed through an aperture using transmission line model. The transmission line model is simple and precise and allows taking into account the whole geometrical, electrical, and technological characteristics of the antennas arrays. The proposed transmission line model showed its interest in the design of different multilayered bow-tie antennas and predicted the correct resonance frequency for different applications in telecommunications. To validate the proposed transmission line model, the simulation results obtained are compared with those obtained by the method of moments. The results of simulations are presented and discussed. Using this transmission line approach, the resonant frequency, input impedance, and return loss can be determined simultaneously. The paper reports several simulation results that confirm the validity of the developed model. The obtained results are then presented and discussed.

  20. The Australian Square Kilometre Array Pathfinder: Performance of the Boolardy Engineering Test Array

    OpenAIRE

    McConnell, D.; J. R. Allison; Bannister, K.; Bell, M. E.; Bignall, H. E.; Chippendale, A. P.; Edwards, P. G.; Harvey-Smith, L.; Hegarty, S; Heywood, I.; Hotan, A. W.; Indermuehle, B. T.; Lenc, E.; Marvil, J.; Popping, A.

    2016-01-01

    We describe the performance of the Boolardy Engineering Test Array (BETA), the prototype for the Australian Square Kilometre Array Pathfinder telescope ASKAP. BETA is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarization beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in o...

  1. Optimizing the accuracy of a helical diode array dosimeter: A comprehensive calibration methodology coupled with a novel virtual inclinometer

    Energy Technology Data Exchange (ETDEWEB)

    Kozelka, Jakub; Robinson, Joshua; Nelms, Benjamin; Zhang, Geoffrey; Savitskij, Dennis; Feygelman, Vladimir [Sun Nuclear Corp., Melbourne, Florida 32940 (United States); Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Canis Lupus LLC, Sauk County, Wisconsin 53561 (United States); Division of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Sun Nuclear Corp., Melbourne, Florida 32940 (United States); Division of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States)

    2011-09-15

    Purpose: The goal of any dosimeter is to be as accurate as possible when measuring absolute dose to compare with calculated dose. This limits the uncertainties associated with the dosimeter itself and allows the task of dose QA to focus on detecting errors in the treatment planning (TPS) and/or delivery systems. This work introduces enhancements to the measurement accuracy of a 3D dosimeter comprised of a helical plane of diodes in a volumetric phantom. Methods: We describe the methods and derivations of new corrections that account for repetition rate dependence, intrinsic relative sensitivity per diode, field size dependence based on the dynamic field size determination, and positional correction. Required and described is an accurate ''virtual inclinometer'' algorithm. The system allows for calibrating the array directly against an ion chamber signal collected with high angular resolution. These enhancements are quantitatively validated using several strategies including ion chamber measurements taken using a ''blank'' plastic shell mimicking the actual phantom, and comparison to high resolution dose calculations for a variety of fields: static, simple arcs, and VMAT. A number of sophisticated treatment planning algorithms were benchmarked against ion chamber measurements for their ability to handle a large air cavity in the phantom. Results: Each calibration correction is quantified and presented vs its independent variable(s). The virtual inclinometer is validated by direct comparison to the gantry angle vs time data from machine log files. The effects of the calibration are quantified and improvements are seen in the dose agreement with the ion chamber reference measurements and with the TPS calculations. These improved agreements are a result of removing prior limitations and assumptions in the calibration methodology. Average gamma analysis passing rates for VMAT plans based on the AAPM TG-119 report are 98.4 and 93

  2. Calibration of Modulation Transfer Function of Surface Profilometers with 1D and 2D Binary Pseudo-random Array Standards

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V.; McKinney, Wayne R.; Takacs, Peter Z.

    2008-05-19

    We suggest and describe the use of a binary pseudo-random grating as a standard test surface for calibration of the modulation transfer function of microscopes. Results from calibration of a MicromapTM-570 interferometric microscope are presented.

  3. Calibration of a large hyperpure germanium array for in-vivo detection of the actinides with a tissue-equivalent torso phantom

    International Nuclear Information System (INIS)

    For calibration of the array for internally deposited 238Pu, 239Pu, and 241Am, a tissue-equivalent anthropomorphic phantom, was used for efficiency determinations at the ORNL facility. This phantom consists of a tissue-equivalent torso into which is imbedded an adult male skeleton, interchangeable organs containing a homogeneous distribution of various radionuclides, and two sets of chest overlay plates for simulation of progressively thicker tissue over the chest, as well as differing thoracic fat contents

  4. Stability of modulation transfer function calibration of surface profilometers using binary pseudo-random gratings and arrays with nonideal groove shapes

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitry L.; Yashchuk, Valeriy V.

    2010-03-31

    The major problem of measurement of a power spectral density (PSD) distribution of surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments, which tends to distort the PSD at higher spatial frequencies. The special mathematical properties of binary pseudo-random patterns make them an ideal basis for developing MTF calibration test surfaces. Two-dimensional binary pseudo-random arrays (BPRAs) have been fabricated and used for the MTF calibration of the MicroMap{trademark}-570 interferometric microscope with all available objectives. An investigation into the effects of fabrication imperfections on the quality of the MTF calibration and a procedure for accounting for such imperfections are presented.

  5. Calibrated single-plunge bipolar electrode array for mapping myocardial vector fields in three dimensions during high-voltage transthoracic defibrillation.

    Science.gov (United States)

    Deale, O C; Ng, K T; Kim-Van Housen, E J; Lerman, B B

    2001-08-01

    Mapping of the myocardial scalar electric potential during defibrillation is normally performed with unipolar electrodes connected to voltage dividers and a global potential reference. Unfortunately, vector potential gradients that are calculated from these data tend to exhibit a high sensitivity to measurement errors. This paper presents a calibrated single-plunge bipolar electrode array (EA) that avoids the error sensitivity of unipolar electrodes. The EA is triaxial, uses a local potential reference, and simultaneously measures all three components of the myocardial electric field vector. An electrode spacing of approximately 500 microm allows the EA to be direct-coupled to high-input-impedance, isolated, differential amplifiers and eliminates the need for voltage dividers. Calibration is performed with an electrolytic tank in which an accurately measured, uniform electric field is produced. For each EA, unique calibration matrices are determined which transform potential difference readings from the EA to orthogonal components of the electric field vector. Elements of the matrices are evaluated by least squares multiple regression analysis of data recorded during rotation of the electric field. The design of the electrolytic tank and electrode holder allows the electric field vector to be rotated globally with respect to the electrode axes. The calibration technique corrects for both field perturbation by the plunge electrode body and deviations from orthogonality of the electrode axes. A unique feature of this technique is that it eliminates the need for mechanical measurement of the electrode spacing. During calibration, only angular settings and voltages are recorded. For this study, ten EAs were calibrated and their root-mean-square (rms) errors evaluated. The mean of the vector magnitude rms errors over the set of ten EAs was 0.40% and the standard deviation 0.07%. Calibrated EAs were also tested for multisite mapping in four dogs during high

  6. Effects of the Number of Active Receiver Channels on the Sensitivity of a Reflector Antenna System with a Multi-Beam Wideband Phased Array Feed

    CERN Document Server

    Iupikov, O

    2016-01-01

    A method for accurate modeling of a reflector antenna system with a wideband phased array feed is presented and used to study the effects of the number of active antenna elements and associated receiving channels on the receiving sensitivity of the antenna system. Numerical results are shown for a practical design named APERTIF that is currently under developed at The Netherlands Institute for Radio Astronomy (ASTRON).

  7. The Allen Telescope Array

    Science.gov (United States)

    Bower, Geoffrey C.; Allen Telescope Array Team

    2010-01-01

    The ATA is a 42-element centimeter wavelength array located in Hat Creek, California and jointly operated by UC Berkeley Radio Astronomy Laboratory and the SETI Institute. Since the ATA dedication in Fall 2007, activities have been focused on commissioning the array, retrofitting a handful of components including the feed, developing an operations model, creation of pipeline processing for correlator imaging data, early science observations, and launching of the major surveys for which the telescope was built. The retrofit of the feed improves feed mechanical robustness as well as high frequency performance. Science programs launched include imaging radio transient and static sky surveys (ATATS and PiGSS), commensal SETI and transient surveys of the Galactic Center, targeted SETI observations of nearby stars, the Fly's Eye transient survey, broadband spectra of nearby star-forming galaxies, polarimetric observations of bright radio sources, observations of hydrogen in nearby galaxies and galaxy groups, molecular line observations in the Galaxy, and observations of Jupiter and the Moon. The baseline Square Kilometer Array (SKA) design, a large-N-small-diameter (LNSD) array with wide-band single-pixel feeds and an offset Gregorian antenna, bears a strong resemblance to the ATA. Additional ATA contributions to the SKA include configuration studies for LNSD arrays, the use of fiber optics for broadband data transmission, the use of flexible FPGA-based digital electronics, passive cooling of antennas, and implementation of commensal observing modes. The ATA is currently used for exploration of calibration and imaging algorithms necessary for the SKA. I will summarize current technical status and performance, the results from early science and surveys, and ATA contributions to SKA development.

  8. The Australian Square Kilometre Array Pathfinder: Performance of the Boolardy Engineering Test Array

    Science.gov (United States)

    McConnell, D.; Allison, J. R.; Bannister, K.; Bell, M. E.; Bignall, H. E.; Chippendale, A. P.; Edwards, P. G.; Harvey-Smith, L.; Hegarty, S.; Heywood, I.; Hotan, A. W.; Indermuehle, B. T.; Lenc, E.; Marvil, J.; Popping, A.; Raja, W.; Reynolds, J. E.; Sault, R. J.; Serra, P.; Voronkov, M. A.; Whiting, M.; Amy, S. W.; Axtens, P.; Ball, L.; Bateman, T. J.; Bock, D. C.-J.; Bolton, R.; Brodrick, D.; Brothers, M.; Brown, A. J.; Bunton, J. D.; Cheng, W.; Cornwell, T.; DeBoer, D.; Feain, I.; Gough, R.; Gupta, N.; Guzman, J. C.; Hampson, G. A.; Hay, S.; Hayman, D. B.; Hoyle, S.; Humphreys, B.; Jacka, C.; Jackson, C. A.; Jackson, S.; Jeganathan, K.; Joseph, J.; Koribalski, B. S.; Leach, M.; Lensson, E. S.; MacLeod, A.; Mackay, S.; Marquarding, M.; McClure-Griffiths, N. M.; Mirtschin, P.; Mitchell, D.; Neuhold, S.; Ng, A.; Norris, R.; Pearce, S.; Qiao, R. Y.; Schinckel, A. E. T.; Shields, M.; Shimwell, T. W.; Storey, M.; Troup, E.; Turner, B.; Tuthill, J.; Tzioumis, A.; Wark, R. M.; Westmeier, T.; Wilson, C.; Wilson, T.

    2016-09-01

    We describe the performance of the Boolardy Engineering Test Array, the prototype for the Australian Square Kilometre Array Pathfinder telescope. Boolardy Engineering Test Array is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarisation beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of Boolardy Engineering Test Array's performance: sensitivity, beam characteristics, polarimetric properties, and image quality. We summarise the astronomical science that it has produced and draw lessons from operating Boolardy Engineering Test Array that will be relevant to the commissioning and operation of the final Australian Square Kilometre Array Path telescope.

  9. Whole body counter calibration using Monte Carlo modeling with an array of phantom sizes based on national anthropometric reference data

    International Nuclear Information System (INIS)

    During construction of the whole body counter (WBC) at the Children's Nutrition Research Center (CNRC), efficiency calibration was needed to translate acquired counts of 40K to actual grams of potassium for measurement of total body potassium (TBK) in a diverse subject population. The MCNP Monte Carlo n-particle simulation program was used to describe the WBC (54 detectors plus shielding), test individual detector counting response, and create a series of virtual anthropomorphic phantoms based on national reference anthropometric data. Each phantom included an outer layer of adipose tissue and an inner core of lean tissue. Phantoms were designed for both genders representing ages 3.5 to 18.5 years with body sizes from the 5th to the 95th percentile based on body weight. In addition, a spherical surface source surrounding the WBC was modeled in order to measure the effects of subject mass on room background interference. Individual detector measurements showed good agreement with the MCNP model. The background source model came close to agreement with empirical measurements, but showed a trend deviating from unity with increasing subject size. Results from the MCNP simulation of the CNRC WBC agreed well with empirical measurements using BOMAB phantoms. Individual detector efficiency corrections were used to improve the accuracy of the model. Nonlinear multiple regression efficiency calibration equations were derived for each gender. Room background correction is critical in improving the accuracy of the WBC calibration.

  10. Whole body counter calibration using Monte Carlo modeling with an array of phantom sizes based on national anthropometric reference data.

    Science.gov (United States)

    Shypailo, R J; Ellis, K J

    2011-05-21

    During construction of the whole body counter (WBC) at the Children's Nutrition Research Center (CNRC), efficiency calibration was needed to translate acquired counts of (40)K to actual grams of potassium for measurement of total body potassium (TBK) in a diverse subject population. The MCNP Monte Carlo n-particle simulation program was used to describe the WBC (54 detectors plus shielding), test individual detector counting response, and create a series of virtual anthropomorphic phantoms based on national reference anthropometric data. Each phantom included an outer layer of adipose tissue and an inner core of lean tissue. Phantoms were designed for both genders representing ages 3.5 to 18.5 years with body sizes from the 5th to the 95th percentile based on body weight. In addition, a spherical surface source surrounding the WBC was modeled in order to measure the effects of subject mass on room background interference. Individual detector measurements showed good agreement with the MCNP model. The background source model came close to agreement with empirical measurements, but showed a trend deviating from unity with increasing subject size. Results from the MCNP simulation of the CNRC WBC agreed well with empirical measurements using BOMAB phantoms. Individual detector efficiency corrections were used to improve the accuracy of the model. Nonlinear multiple regression efficiency calibration equations were derived for each gender. Room background correction is critical in improving the accuracy of the WBC calibration.

  11. Whole body counter calibration using Monte Carlo modeling with an array of phantom sizes based on national anthropometric reference data

    Science.gov (United States)

    Shypailo, R. J.; Ellis, K. J.

    2011-05-01

    During construction of the whole body counter (WBC) at the Children's Nutrition Research Center (CNRC), efficiency calibration was needed to translate acquired counts of 40K to actual grams of potassium for measurement of total body potassium (TBK) in a diverse subject population. The MCNP Monte Carlo n-particle simulation program was used to describe the WBC (54 detectors plus shielding), test individual detector counting response, and create a series of virtual anthropomorphic phantoms based on national reference anthropometric data. Each phantom included an outer layer of adipose tissue and an inner core of lean tissue. Phantoms were designed for both genders representing ages 3.5 to 18.5 years with body sizes from the 5th to the 95th percentile based on body weight. In addition, a spherical surface source surrounding the WBC was modeled in order to measure the effects of subject mass on room background interference. Individual detector measurements showed good agreement with the MCNP model. The background source model came close to agreement with empirical measurements, but showed a trend deviating from unity with increasing subject size. Results from the MCNP simulation of the CNRC WBC agreed well with empirical measurements using BOMAB phantoms. Individual detector efficiency corrections were used to improve the accuracy of the model. Nonlinear multiple regression efficiency calibration equations were derived for each gender. Room background correction is critical in improving the accuracy of the WBC calibration.

  12. Feed Feeds: Managing Feeds Using Feeds

    OpenAIRE

    Wilde, Erik; Pesenson, Igor

    2008-01-01

    Feeds have become an important information channel on the Web, but the management of feed metadata so far has received little attention. It is hard for feed publishers to manage and publish their feed information in a unified format, and for feed consumers to manage and use their feed subscription data across various feed readers, and to share it with other users. We present a system for managing feed metadata using feeds, which we call "feed feeds". Because these feeds are Atom feeds, the wi...

  13. Design of Amplitude and Phase Calibration System for Digital Array MST Radar%数字阵列MST雷达幅相标校系统设计

    Institute of Scientific and Technical Information of China (English)

    刘一峰

    2012-01-01

    数字阵列MST雷达是有源相控阵气象雷达,可探测中层、平流层和对流层的大气风场.该雷达采用了分布式全固态发射技术以及数字波束形成技术,减少了硬件的复杂性,提高了探测性能,更适用于复杂天气过程的探测.幅相标校技术是数字阵列MST雷达的关键技术之一,该技术可以提高雷达的幅相一致性,从而提高雷达的探测性能.文中首先介绍了数字阵列MST雷达的系统组成,然后采用了矩阵分析的方法推导了幅相标校算法,给出了幅相标校系统设计流程,最后得出了一组实际标校结果.%The digital array MST radar is an active phased-array meteorological radar,which measures winds in middle-atmosphere,stratosphere and troposphere.The radar applies distributing solid transmitter technology and digital beamforming technology,which can decrease the complexities of hardware,and improve the capability of radar,also adapt to the exploration of complex weather processes.The technology of amplitude and phase calibration is one of the key technologies to digital array radars,which can improve the amplitude-phase consistence of radar,and can also improve the capability of radar.The composition of the radar is presented at first,and the method of amplitude and phase calibration is discussed with matrix analysis,and then a design of amplitude and phase calibration system is given,at last a true result is given.

  14. 焦面场分析与相控阵馈源设计%Focal Field Analysis and Phased Array Feed Design

    Institute of Scientific and Technical Information of China (English)

    伍洋; 杜彪; 刘肖萌; 金乘进; 甘恒谦; 龚书喜

    2013-01-01

    A method of calculating focal field is introduced, and the connection between focal field, which depends on the reflector geometry, and the aperture field of feed is analyzed. Based on focal field distribution, a design method of phased array feed, including element spacing determination, phased array scale, and excitations for expected radiation pattern is presented. Two phased array feeds are designed to realize shaped beams for an un-shaped Cassegrain antenna and shaped scanning beams for a prime-focus parabolic antenna respectively. The numerical analyses demonstrate the effectiveness of the approach.%  该文介绍了焦面场的计算方法及其与反射面焦径比的关系,分析了焦面场与馈源口径场的联系,并建立了基于焦面场分析进行相控阵馈源设计的方法,包括确定单元间距、阵列规模以及实现目标方向图所需要的激励。按照这一方法,分别以未赋形卡塞格伦天线和前馈抛物面天线为对象,设计了各自的相控阵馈源以实现赋形波束的效果,并在后者上验证了波束扫描性能。通过仿真,天线性能实现了预定目标,证明了设计方法的有效性。

  15. Wide-field broadband radio imaging with phased array feeds: a pilot multi-epoch continuum survey with ASKAP-BETA

    CERN Document Server

    Heywood, I; Marvil, J; Allison, J R; Ball, L; Bell, M E; Bock, D C -J; Brothers, M; Bunton, J D; Chippendale, A P; Cooray, F; Cornwell, T J; DeBoer, D; Edwards, P; Gough, R; Gupta, N; Harvey-Smith, L; Hay, S; Hotan, A W; Indermuehle, B; Jacka, C; Jackson, C A; Johnston, S; Kimball, A E; Koribalski, B S; Lenc, E; Macleod, A; McClure-Griffiths, N; McConnell, D; Mirtschin, P; Murphy, T; Neuhold, S; Norris, R P; Pearce, S; Popping, A; Qiao, R Y; Reynolds, J E; Sadler, E M; Sault, R J; Schinckel, A E T; Serra, P; Shimwell, T W; Stevens, J; Tuthill, J; Tzioumis, A; Voronkov, M A; Westmeier, T; Whiting, M T

    2016-01-01

    The Boolardy Engineering Test Array is a 6 x 12 m dish interferometer and the prototype of the Australian Square Kilometre Array Pathfinder (ASKAP), equipped with the first generation of ASKAP's phased array feed (PAF) receivers. These facilitate rapid wide-area imaging via the deployment of simultaneous multiple beams within a 30 square degree field of view. By cycling the array through 12 interleaved pointing positions and using 9 digitally formed beams we effectively mimic a traditional 1 hour x 108 pointing survey, covering 150 square degrees over 711 - 1015 MHz in 12 hours of observing time. Three such observations were executed over the course of a week. We verify the full bandwidth continuum imaging performance and stability of the system via self-consistency checks and comparisons to existing radio data. The combined three epoch image has arcminute resolution and a 1-sigma thermal noise level of 375 micro-Jy per beam, although the effective noise is a factor 3 higher due to residual sidelobe confusion...

  16. Using muon rings for the optical throughput calibration of the SST-1M prototype for the Cherenkov Telescope Array

    CERN Document Server

    Toscano, S; Bilnik, W; Błocki, J; Bogacz, L; Bulik, T; Cadoux, F; Christov, A; Curyło, M; della Volpe, D; Dyrda, M; Favre, Y; Frankowski, A; Grudnik, Ł; Grudzińska, M; Heller, M; Idźkowski, B; Jamrozy, M; Janiak, M; Kasperek, J; Lalik, K; Lyard, E; Mach, E; Mandat, D; Marszałek, A; Michałowski, J; Moderski, R; Montaruli, T; Neronov, A; Niemiec, J; Ostrowski, M; Paśko, P; Pech, M; Porcelli, A; Rameez, M; Rajda, P; Schioppa, E jr; Schovanek, P; Seweryn, K; Skowron, K; Sliusar, V; Sowiński, M; Stawarz, Ł; Stodulska, M; Stodulski, M; Pujadas, I Troyano; Walter, R; Więcek, M; Zagdański, A; Ziętara, K; Żychowski, P

    2015-01-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) are ground-based instruments devoted to the study of very high energy gamma-rays coming from space. The detection technique consists of observing images created by the Cherenkov light emitted when gamma rays, or more generally cosmic rays, propagate through the atmosphere. While in the case of protons or gamma-rays the images present a filled and more or less elongated shape, energetic muons penetrating the atmosphere are visualised as characteristic circular rings or arcs. A relatively simple analysis of the ring images allows the reconstruction of all the relevant parameters of the detected muons, such as the energy, the impact parameter, and the incoming direction, with the final aim to use them to calibrate the total optical throughput of the given IACT telescope. We present the results of preliminary studies on the use of images created by muons as optical throughput calibrators of the single mirror small size telescope prototype SST-1M proposed for the Ch...

  17. A Design Of Feeding Network For A Dual-Linear Polarization, Stacked, Probe-Fed Microstrip Patch Antenna Array

    DEFF Research Database (Denmark)

    Jaworski, G.; Krozer, Viktor

    2004-01-01

    Components of multilayer feed network are presented for application in broad-band dual-linear polarized stacked C-band antenna. Measurement results of wide band matching circuits and different types of power divider networks constituting parts of BFN demonstrate wideband operation. Suitable...

  18. Performance Analysis of Corporate Feed Rectangular Patch Element and Circular Patch Element 4x2 Microstrip Array Antennas

    Directory of Open Access Journals (Sweden)

    Md. Tanvir Ishtaique-ul Huque

    2011-08-01

    Full Text Available This paper present simple, slim, low cost and high gain circular patch and rectangular patch microstrip array antenna, with the details steps of design process, operate in X-band(8 GHz to 12 GHz and it provides a mean to choose the effective one based on the performance analysis of both of these array antennas. The method of analysis, design and development of these array antennas are explained completely here and analyses are carried out for 4x2 arrays. The simulation has been performed by using commercially available antenna simulator, SONNET version V12.56, to compute the current distribution, return loss response and radiation pattern. The proposed antennas are designed by using Taconic TLY-5 dielectric substrate with permittivity, er = 2.2 and height, h =1.588 mm. In all cases we get return losses in the range -4.96 dB to -25.21 dB at frequencies around 10 GHz. The gain of these antennas as simulated are found above 6 dB and side lobe label is maintained lower than main lobe. Operating frequency of these antennas is 10 GHz so these antennas are suitable for X-band application.

  19. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    Science.gov (United States)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.; Dunn, D.

    1992-04-01

    The topics covered include the following: (1) performance analysis of the Gregorian tri-reflector; (2) design and performance of the type 6 reflector antenna; (3) a new spherical main reflector system design; (4) optimization of reflector configurations using physical optics; (5) radiometric array design; and (7) beam efficiency studies.

  20. Calibration of mixed-polarization interferometric observations

    CERN Document Server

    Marti-Vidal, Ivan; Conway, John; Zensus, Anton J

    2016-01-01

    Heterodyne receivers register the sky signal on either a circular polarization basis (where it is split into left-hand and right-hand circular polarization) or a linear polarization basis (where it is split into horizontal and vertical linear polarization). We study the problem of interferometric observations performed with telescopes that observe on different polarization bases, hence producing visibilities that we call "mixed basis" (i.e., linear in one telescope and circular in the other). We present novel algorithms for the proper calibration and treatment of such interferometric observations and test our algorithms with both simulations and real data. The use of our algorithms will be important for the optimum calibration of forthcoming observations with the Atacama Large mm/submm Array (ALMA) in very-long-baseline interferometry (VLBI) mode. Our algorithms will also allow us to optimally calibrate future VLBI observations at very high data rates (i.e., wide bandwidths), where linear-polarization feeds w...

  1. Calibration and Application of an Array of Portable FTIR Spectrometers (EM27/SUN) for Detecting Greenhouse Gas Emissions

    Science.gov (United States)

    Frey, M.; Chelin, P.; Fratacci, T.; Schäfer, K.; Xueref-Remy, I.; Te, Y. V.; Jeseck, P.; Janssen, C.; Vogel, F. R.; Hase, F.; Blumenstock, T.; Kiel, M.; Sha, M. K.; Tu, Q.; Gross, J.; Gizaw, G.

    2015-12-01

    Anthropogenic global warming is mainly driven by a continuing increase of atmospheric greenhouse gases abundances. Precise knowledge of the variable atmospheric concentrations is of utmost importance for the quantification of sinks and sources of these gases. For global observations of column-averaged dry air mole fractions of greenhouse gases, satellite-borne instruments (e.g. GOSAT or OCO-2) are used. These instruments are validated against a network of ground-based high resolution Fourier-Transform Infrared (FTIR) spectrometers. This network, called TCCON (Total Carbon Column Observing Network), provides column-averaged abundances with reference precision and accuracy. However, these instruments are expensive, logistically demanding and stationary, so TCCON is less adequate for the quantification of sinks and sources on a regional scale. Recently the Karlsruhe Institute of Technology developed a portable FTIR spectrometer (EM27/SUN) together with Bruker Optics, Ettlingen. In addition to filling in the spatial gaps of the existing TCCON network for better global coverage, a set of these spectrometers can be arranged for detecting localized sinks and sources of greenhouse gases on a regional level, e.g. major cities or fracking areas. Due to their long lifetime, CO2 and CH4 emissions of these sources only introduce a small enhancement to the accumulated atmospheric background abundance. Therefore, high precision and stability are a prerequisite for the measurements. We present a rigorous calibration procedure for a quintuple of EM27/SUN spectrometers. Moreover, we show results from a test campaign conducted 2014 in the major city of Berlin, Germany. We demonstrate that the CO2 emissions of Berlin can be clearly identified in the observations. Measurement results are compared with a simple dispersion model. Finally, a comparison between Berlin data and data from a recent campaign in the megacity Paris is shown.

  2. Calibration aspects of a polarimetric phased array airborne SAR [L'Etalonnage d'un SAR aeroporte polarimetrique a antenna active}

    NARCIS (Netherlands)

    Snoeij, P.; Hoogeboom, P.; Koomen, P.J.; Vermeulen, B.C.B.; Paquay, M.H.A.; Pouwels, H.

    1994-01-01

    Purpose of calibration is to get an accurate and Precise instrument. The precision of the instrument can be determined using internal calibration, while the accuracy is denoted with absolute calibration. With internal calibration only the instrument is considered. Because of practical considerations

  3. Computational Methods and Theoretical Results for the Ka-Band Array Feed Compensation System-Deformable Flat Plate Experiment at DSS 14

    Science.gov (United States)

    Imbriale, W. A.; Hoppe, D. J.

    1999-10-01

    This article documents the computational methods and theoretical results for the deformable flat plate (DFP), array feed compensation system (AFCS), monopulse tracking system, and combined AFCS--DFP used for compensating the gravity-induced distortions on the DSN's 70-m antenna. These systems were utilized in an experiment designed to verify gravity compensation and tracking performance of the 70-m antenna at 31.8--32.2 GHz (Ka-band). This experiment took place from November 1998 through February 1999 and consisted of both quasar and spacecraft observations. The theoretical results are compared with the experimental data. The analytical tools are also used to document and understand the characteristics of each system.

  4. The Australian Square Kilometre Array Pathfinder: System Architecture and Specifications of the Boolardy Engineering Test Array

    CERN Document Server

    Hotan, A W; Harvey-Smith, L; Humphreys, B; Jeffs, B D; Shimwell, T; Tuthill, J; Voronkov, M; Allen, G; Amy, S; Ardern, K; Axtens, P; Ball, L; Bannister, K; Barker, S; Bateman, T; Beresford, R; Bock, D; Bolton, R; Bowen, M; Boyle, B; Braun, R; Broadhurst, S; Brodrick, D; Brooks, K; Brothers, M; Brown, A; Cantrall, C; Carrad, G; Chapman, J; Cheng, W; Chippendale, A; Chung, Y; Cooray, F; Cornwell, T; Davis, E; de Souza, L; DeBoer, D; Diamond, P; Edwards, P; Ekers, R; Feain, I; Ferris, D; Forsyth, R; Gough, R; Grancea, A; Gupta, N; Guzman, JC; Hampson, G; Haskins, C; Hay, S; Hayman, D; Hoyle, S; Jacka, C; Jackson, C; Jackson, S; Jeganathan, K; Johnston, S; Joseph, J; Kendall, R; Kesteven, M; Kiraly, D; Koribalski, B; Leach, M; Lenc, E; Lensson, E; Li, L; Mackay, S; Macleod, A; Maher, T; Marquarding, M; McClure-Griffiths, N; McConnell, D; Mickle, S; Mirtschin, P; Norris, R; Neuhold, S; Ng, A; O'Sullivan, J; Pathikulangara, J; Pearce, S; Phillips, C; Qiao, RY; Reynolds, J E; Rispler, A; Roberts, P; Roxby, D; Schinckel, A; Shaw, R; Shields, M; Storey, M; Sweetnam, T; Troup, E; Turner, B; Tzioumis, A; Westmeier, T; Whiting, M; Wilson, C; Wilson, T; Wormnes, K; Wu, X

    2014-01-01

    This paper describes the system architecture of a newly constructed radio telescope - the Boolardy Engineering Test Array, which is a prototype of the Australian Square Kilometre Array Pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a 6-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least 9 dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.

  5. Determination of nitrofurans in animal feeds by liquid chromatography-UV photodiode array detection and liquid chromatography-ionspray tandem mass spectrometry.

    Science.gov (United States)

    Barbosa, Jorge; Moura, Sara; Barbosa, Rita; Ramos, Fernando; da Silveira, Maria Irene Noronha

    2007-03-14

    Within the EU, the use of nitrofurans is prohibited in food production animals. For this reason detection of these compounds in feedingstuffs, at whatever limit, constitutes an offence under EU legislation. This detection generally involves the use of analytical methods with limits of quantification lowers than 1 mg kg(-1). These procedures are unsuitable for the detection and confirmation of trace amounts of nitrofurans in feedingstuffs due to contamination. It is well known that very low concentrations of these compounds can be the source of residues of nitrofuran metabolites in meat and other edible products obtained from animals consuming the contaminated feed. The present multi-compound method was capable of measuring very low concentrations of nitrofurantoin (NFT), nitrofurazone (NFZ), furazolidone (FZD) and furaltadone (FTD) in animal feed using nifuroxazide (NXZ) as internal standard. Following ethyl acetate extraction at mild alkaline conditions and purification on NH2 column, the nitrofurans are determined using liquid chromatography with photodiode-array detection (LC-DAD). It was observed a CCalpha ranged from 50 to 100 microg kg(-1). The liquid chromatography-tandem mass spectrometric (LC-MS/MS) procedure was used to confirm the identity of the suspected presence of any of the nitrofuran compounds. PMID:17386735

  6. Fast Active Error Calibration Algorithm for Array ChanelUncertainty%阵列通道不一致性误差快速有源校正算法

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    针对阵列通道不一致性引起的幅相误差校正问题,基于多级维纳滤波器(MSWF),该文提出幅相误差快速校正的简化的多级维纳滤波器(SMSWF)算法。SMSWF算法利用校正源的方位和波形信息对阵列幅相参数进行估计,无需估计协方差矩阵和进行特征值分解,大大地减小了计算量,且具有与特征分解方法相同的幅相参数估计性能。研究发现,单个信源入射到阵列且信源波形已知时,SMSWF算法获得的信号子空间等价于特征分解法得到的信号子空间,这表明SMSWF算法能够替代特征分解法,从而极大减小基于特征分解法的信号处理方法的计算量。大量计算机仿真和消声水池试验验证了SMSWF算法的优越性能。%Aiming the error calibration for the array channel uncertainty, a new fast algorithm named Simplified Multi-Stage Wiener Filter (SMSWF) based on the Multi-Stage Wiener Filter (MSWF) is proposed. The SMSWF takes the advantages of the DOA and the waveform of the cooperative source to estimate the gain and the phase factors, and it does not need to estimate the covariance matrix and the eigendecomposition operations. Compared with the eigendecomposition algorithm, the SMSWF has the same performance for estimating gain and phase factors while greatly reduce the complexity. The researches show that if a single source with a known waveform incidence on the array, the signal subspaces obtained by the SMSWF and one obtained by the eigendecomposition are equipollent, which demonstrate that the SMSWF is able to replace the eigendecomposition. The complexity of signal processing methods based on the eigendecomposition can greatly be reduced by replacing the eigendecomposition with the SMSWF. The extensive computer simulations and experiment in anechoice water tank show the superiori performance of the proposed algorithm.

  7. Calibrating a detector array for in vivo dosimetry beam electron In this work present a set of detectors calibration for measurements in vivo dose at the entrance of the radiation beam in electron beams; Calibracion de un conjunto de detectores para la dosimetria in vivo de haces de electrones

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Jurado, T.; Jornet Sala, N.; Carrasco de Fez, P.; Eudaldo Puell, T.; Latorre Mussoll, A.; Rodriguez Latorre, D.; Ruiz Martinez, A.; Ribas Morales, M.

    2013-07-01

    In particular we have determined the variation in sensitivity of the diode depending on the field size, power, angle of incidence, DFS, temperature and cumulative dose. From these results we provide a methodology for calibrating a diode array for use in routine. The application of correction factors to reading diodes are warranted when the irradiation conditions differ from the reference by the level of tolerance among the expected dose and the dose obtained. (Author)

  8. A flux calibration device for the SuperNova Integral Field Spectrograph (SNIFS)

    CERN Document Server

    Lombardo, Simona; Hoffmann, Akos; Kowalski, Marek; Kuesters, Daniel; Reif, Klaus; Rigault, Mickael

    2014-01-01

    Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1 degree. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our "telescope + SNIFS system" at the required precision.

  9. A flux calibration device for the SuperNova Integral Field Spectrograph (SNIFS)

    Science.gov (United States)

    Lombardo, Simona; Aldering, Greg; Hoffmann, Akos; Kowalski, Marek; Kuesters, Daniel; Reif, Klaus; Rigault, Michael

    2014-07-01

    Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1°. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our "telescope + SNIFS system" at the required precision.

  10. Method of Calibrating Array Antenna in Near Field and Its Application in Beam-forming%阵列天线近场校准方法及在波束形成中的应用

    Institute of Scientific and Technical Information of China (English)

    杨雷明; 李强; 孙广俊

    2014-01-01

    Testing antenna in far field is much more difficulty since its big antenna caliber of large scale phased ar-ray antenna, and this can be effectively solved by using method of testing antenna in near field. The amplitude and phase error on large scale antenna array is tested and calibrated by using method of testing antenna in near fields in practical engineering application. The test results show that this method can be used to evaluate amplitude and phase consistency of array antenna. In respect to closed-loop calibration of the receiver, the antenna error calibra-tion can distinctly reduce side lobes after beam-forming, and the angle measurement deviation decreases obvious-ly, especially in the low frequency band of shortwave.%大型相控阵天线阵列由于天线口径很大,给天线远场测试带来很多困难,天线近场测试方法可以有效解决这类问题。本文在实际工程中利用天线近场测试方法对大型天线阵列的幅相误差进行了测试及校准。试验结果表明,此方法可以用于评估阵列天线的一致性。波束形成后,相对于接收机闭环校准,天线误差校准可以明显降低旁瓣,并且测角偏差明显减少,在短波低频段表现尤为突出。

  11. 基于辅助阵元校正法的柔性阵列阵元位置校正%The calibration of the flexible array's sensor position based on instrumental sensor method

    Institute of Scientific and Technical Information of China (English)

    林晋美; 涂英; 蔡惠智

    2007-01-01

    Two methods to calibrate the sensor positions of the large flexible array had been proposed here. Sensor locations uncertainty can severely degrade the performance of directional system after the array had been lied under the sea bottom. The two closer sensors of the array were used as the instrumental sensors to estimate DOAs and the elements' phases at the same time. There were at least two sets of calibration data from angularly separated source positions to estimate the sensors positions and the array shape. In order to calibrate the array shape correctly, we had compared the two methods through a mount of simulation to find out which one would be more robust while the instrumental sensors were disturbed.And the more robust method of MUSIC instrumental sensors method had been used for the data of sea tests from the seatrial.%本文介绍了两种用于校正大型柔性声纳阵列的阵元位置的方法.在阵列进行海底铺设后,阵元位置的不确定,会大大降低声纳搜索方位的性能.辅助阵元校正方法考虑使用阵上较短距离间隔的阵元作为辅助阵元来对信号到达角和阵元相对相位同时进行估计.并从至少两组不同方位声源点测得的数据,获得阵元的相对坐标位置,得到阵形.为了保证校正的有效性,我们比较了这两种辅助阵元校正方法,通过大量的仿真试验比较它们对辅助阵元误差扰动的敏感度,并选择了宽容性较好的MUSIC辅助阵元方法进行了实际的海上试验.

  12. The Australian Square Kilometre Array Pathfinder: Performance of the Boolardy Engineering Test Array

    CERN Document Server

    McConnell, D; Bannister, K; Bell, M E; Bignall, H E; Chippendale, A P; Edwards, P G; Harvey-Smith, L; Hegarty, S; Heywood, I; Hotan, A W; Indermuehle, B T; Lenc, E; Marvil, J; Popping, A; Raja, W; Reynolds, J E; Sault, R J; Serra, P; Voronkov, M A; Whiting, M; Amy, S W; Axtens, P; Ball, L; Bateman, T J; Bock, D C -J; Bolton, R; Brodrick, D; Brothers, M; Brown, A J; Bunton, J D; Cheng, W; Cornwell, T; DeBoer, D; Feain, I; Gough, R; Gupta, N; Guzman, J C; Hampson, G A; Hay, S; Hayman, D B; Hoyle, S; Humphreys, B; Jacka, C; Jackson, C A; Jackson, S; Jeganathan, K; Joseph, J; Koribalski, B S; Leach, M; Lensson, E S; MacLeod, A; Mackay, S; Marquarding, M; McClure-Griffiths, N M; Mirtschin, P; Mitchell, D; Neuhold, S; Ng, A; Norris, R; Pearce, S; Qiao, R Y; Schinckel, A E T; Shields, M; Shimwell, T W; Storey, M; Troup, E; Turner, B; Tuthill, J; Tzioumis, A; Wark, R M; Westmeier, T; Wilson, C; Wilson, T

    2016-01-01

    We describe the performance of the Boolardy Engineering Test Array (BETA), the prototype for the Australian Square Kilometre Array Pathfinder telescope ASKAP. BETA is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarization beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of BETA's performance: sensitivity, beam characteristics, polarimetric properties and image quality. We summarise the astronomical science that it has produced and draw lessons from operating BETA that will be relevant to the commissioning and operation of the final ASKAP telescope.

  13. Radio Interferometric Calibration Using a Riemannian Manifold

    CERN Document Server

    Yatawatta, Sarod

    2013-01-01

    In order to cope with the increased data volumes generated by modern radio interferometers such as LOFAR (Low Frequency Array) or SKA (Square Kilometre Array), fast and efficient calibration algorithms are essential. Traditional radio interferometric calibration is performed using nonlinear optimization techniques such as the Levenberg-Marquardt algorithm in Euclidean space. In this paper, we reformulate radio interferometric calibration as a nonlinear optimization problem on a Riemannian manifold. The reformulated calibration problem is solved using the Riemannian trust-region method. We show that calibration on a Riemannian manifold has faster convergence with reduced computational cost compared to conventional calibration in Euclidean space.

  14. The Murchison Widefield Array

    NARCIS (Netherlands)

    Mitchell, Daniel A.; Greenhill, Lincoln J.; Ord, Stephen M.; Bernardi, Gianni

    2010-01-01

    It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imagin

  15. The Allen Telescope Array as Square Kilometer Array Pathfinder

    Science.gov (United States)

    Bower, Geoffrey C.

    2007-12-01

    The Allen Telescope Array (ATA) is a new radio interferometer that has begun scientific operations in 2007. Many of the technologies, techniques, and observing modes developed for the ATA are directly applicable to the Square Kilometer Array (SKA). The ATA is a pioneer of the LNSD, which refers to a large number (LN) of small diameter (SD) dishes to create the array. This concept underlies nearly all SKA designs. Other relevant technologies are the offset Gregorian ATA antenna, the ATA wideband log periodic feed, transport of broadband data over fiber optic cables, and flexible digital signal processing electronics. The small dishes of the ATA gives it extraordinary wide-field imaging and survey capability but also require new solutions for calibration and imaging. Real time imaging, rapid response to transients, and thinking telescope technology are also under development. Finally, the ATA is developing commensal observing modes, which enable multiple simultaneous science programs, such as SETI, transient surveys, and HI surveys. Opportunities exist for community members to perform scientific investigations as well as develop techniques and technology for the SKA through use of the ATA.

  16. Field Testing, Installation, and Calibration of a new Data Acquisition System for the USGS-Stanford-Berkley Ultra-Low Frequency Electromagnetic (ULFEM) Array

    Science.gov (United States)

    Creasy, N.; Gardner, J.; Spritzer, J. M.; Keneally, I.; Glen, J. M.; McPhee, D.; Klemperer, S. L.

    2013-12-01

    Since 2006, Stanford University, USGS, and UC Berkeley collaboratively maintain five permanent stations, to measure electric and magnetic data from 0.01 to 40Hz. Each station consists of three orthogonal coil magnetometers and two orthogonal 100m electrodes. The acquisition of ULFEM data helps study possible correlations between electromagnetic fields and seismic events related to the San Andreas Fault system. The current data acquisition system uses a Quanterra Q330 analog-to-digital converter. In 2010, we began development of a new 24-bit digitizing system known as the ULFEM 2010 digitizer in order to replace the Q330. The design of the new recorder was to be more economical and better tailored to the ULFEM network by providing power, calibration, and improved protection from lightning. However, the prototype had many problems, including a daily phase shift, amplifying error, and a time delay of 15 seconds (Bowden, et al., AGU, 2010). Currently, comparative testing of an improved prototype, ULFEM 2013, and the Q330 is taking place at the Jasper Ridge ULFEM station. The ULFEM 2013 contains eight channels that record input from three coil magnetometers, four electrodes, and temperature. Testing is ongoing and involves comparing the coil magnetometer and electrode signals processed by the Q330 and ULFEM 2013 digitizer. Data from the two systems will be compared in the time and frequency domains, and analyses will include calculating error and cross correlations. The ULFEM 2013 digitizer provides power to the magnetometer sensors as well as a calibration coil system (CCS). Every 24 hours, the CCS sends a calibration signal to calibration induction coils fitted to each of the three orthogonal magnetometers with the aim of testing the sensors' sensitivity and accuracy. The CCS produces a frequency sweep of 0.08, 0.51, 5, and 10Hz, creating a field nearly ten times greater than the Earth's field. The CCS consists of open source hardware and an amplifying frequency

  17. Calibration Transfer of Near Infrared Spectrometric Models for Crude Protein of Protein Feed Materials%蛋白饲料原料粗蛋白含量近红外光谱模型转移研究

    Institute of Scientific and Technical Information of China (English)

    丁柯; 张月敬; 沈广辉; 于贤龙; 杨增玲; 刘贤

    2016-01-01

    The near infrared spectrometric quantitative model of protein feed and its sharing in different instruments can greatly improve the utilization efficiency of the model and meet the needs of rapid development of feed industry.Considering the issue of applicability of near infrared spectrometric models for crude protein of protein feed materials,calibration transfer was explored among three types of instruments using spectral subtraction correction,direct standardization and piecewise directs standardiza-tion methods for the first time.Four kinds of protein feed raw materials were involved in the present study,corn protein pow-der,rapeseed meal,fish meal and distillers dried grains with soluble.The experimental instruments included MATRIX-I Fourier transform near infrared instrument (master instrument),Spectrum 400 Fourier transform near infrared instrument (slave 1 instrument),and SupNIR-2750 grating near infrared instrument (slave 2 instrument).Results showed that the spectral data difference for all the samples between the master and slave 2 instrument was relatively small,and the difference between the master and slave 1 instrument,and slave 1 and slave 2 instrument were relatively large.All the root mean square error of predic-tion and bias values after calibration transfer were lower than the values before calibration transfer,except that no improvement was found for the prediction of corn protein powder of slave 2 instrument corrected by piecewise direct standardization method. The relative prediction deviation (RPD)of corn protein powder,rapeseed meal and distillers dried grains with soluble transferred by all three methods were higher than 3,which indicated good predictions,while the RPD of fish meal were all higher than 2.5, which indicated relative good predictions.All three techniques used in the study were effective in the correction of the difference between different instruments for protein feed materials.This study is of important practical

  18. Test surfaces useful for calibration of surface profilometers

    Science.gov (United States)

    Yashchuk, Valeriy V; McKinney, Wayne R; Takacs, Peter Z

    2013-12-31

    The present invention provides for test surfaces and methods for calibration of surface profilometers, including interferometric and atomic force microscopes. Calibration is performed using a specially designed test surface, or the Binary Pseudo-random (BPR) grating (array). Utilizing the BPR grating (array) to measure the power spectral density (PSD) spectrum, the profilometer is calibrated by determining the instrumental modulation transfer.

  19. Determination of seven synthetic dyes in animal feeds and meat by high performance liquid chromatography with diode array and tandem mass detectors.

    Science.gov (United States)

    Zou, Tingting; He, Pingli; Yasen, Amangul; Li, Zhen

    2013-06-01

    An efficient method was developed for the simultaneous determination of seven commonly used synthetic sulfonate dyes (Ponceau 4RC, Sunset yellow, Allura red, Azophloxine, Ponceau xylidine, Erythrosine and Orange II) in animal feed and meat using high performance liquid chromatography (HPLC-DAD) and tandem mass spectrometry (HPLC-MS/MS). Ethanol-ammonia-water (80:1:19, V/V/V) solution was used as extract solution, which can extract target species while reducing interference from the sample matrices. The recoveries of these 7 dyes in animal feed and chicken meat were between 71% and 97% with relative standard deviations less than 14.8%. HPLC-MS/MS was employed as a further means of confirmation to assure accuracy of the results. Limits of detection for these dyes were in the range of 0.02-21.83 ng mL(-1). The proposed method can be applied to confirmative screening of seven commonly used food colorants in feed and meat samples. PMID:23411306

  20. LOFAR Facet Calibration

    Science.gov (United States)

    van Weeren, R. J.; Williams, W. L.; Hardcastle, M. J.; Shimwell, T. W.; Rafferty, D. A.; Sabater, J.; Heald, G.; Sridhar, S. S.; Dijkema, T. J.; Brunetti, G.; Brüggen, M.; Andrade-Santos, F.; Ogrean, G. A.; Röttgering, H. J. A.; Dawson, W. A.; Forman, W. R.; de Gasperin, F.; Jones, C.; Miley, G. K.; Rudnick, L.; Sarazin, C. L.; Bonafede, A.; Best, P. N.; Bîrzan, L.; Cassano, R.; Chyży, K. T.; Croston, J. H.; Ensslin, T.; Ferrari, C.; Hoeft, M.; Horellou, C.; Jarvis, M. J.; Kraft, R. P.; Mevius, M.; Intema, H. T.; Murray, S. S.; Orrú, E.; Pizzo, R.; Simionescu, A.; Stroe, A.; van der Tol, S.; White, G. J.

    2016-03-01

    LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images is challenging due to the presence of direction-dependent calibration errors, caused by imperfect knowledge of the station beam shapes and the ionosphere. Furthermore, the large data volume and presence of station clock errors present additional difficulties. In this paper we present a new calibration scheme, which we name facet calibration, to obtain deep high-resolution LOFAR High Band Antenna images using the Dutch part of the array. This scheme solves and corrects the direction-dependent errors in a number of facets that cover the observed field of view. Facet calibration provides close to thermal noise limited images for a typical 8 hr observing run at ∼ 5\\prime\\prime resolution, meeting the specifications of the LOFAR Tier-1 northern survey.

  1. LOFAR facet calibration

    CERN Document Server

    van Weeren, R J; Hardcastle, M J; Shimwell, T W; Rafferty, D A; Sabater, J; Heald, G; Sridhar, S S; Dijkema, T J; Brunetti, G; Brüggen, M; Andrade-Santos, F; Ogrean, G A; Röttgering, H J A; Dawson, W A; Forman, W R; de Gasperin, F; Jones, C; Miley, G K; Rudnick, L; Sarazin, C L; Bonafede, A; Best, P N; Bîrzan, L; Cassano, R; Chyży, K T; Croston, J H; Ensslin, T; Ferrari, C; Hoeft, M; Horellou, C; Jarvis, M J; Kraft, R P; Mevius, M; Intema, H T; Murray, S S; Orrú, E; Pizzo, R; Simionescu, A; Stroe, A; van der Tol, S; White, G J

    2016-01-01

    LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images is challenging due to the presence of direction dependent calibration errors, caused by imperfect knowledge of the station beam shapes and the ionosphere. Furthermore, the large data volume and presence of station clock errors present additional difficulties. In this paper we present a new calibration scheme, which we name facet calibration, to obtain deep high-resolution LOFAR High Band Antenna images using the Dutch part of the array. This scheme solves and corrects the direction dependent errors in a number of facets that cover the observed field of view. Facet calibration provides close to thermal noise limited images for a typical 8 hr observing run at $\\sim$ 5arcsec resolu...

  2. 应答着陆系统接收天线阵列误差校正%Transponder Landing System Receiving Antenna Array Error Calibration

    Institute of Scientific and Technical Information of China (English)

    杨益欢; 陈阳

    2015-01-01

    Against the error of the spatial smoothing angle measurement technology, which is used by the transponder landing system based on MUSIC algorithm using virtual array, the causes and influencing factors of angle measurement error were analyzed. The author adopted and simulated a comprehensive error correction method combined with the actual. Simulation results show that this method can effectively solve the error, and shows good performance under low SNR. It also shows that the method has a high reliability.%针对应答着陆系统( Transponder Landing System,TLS)利用虚拟阵列基于MUSIC算法的空间平滑测角技术在实际工程中存在测角误差的问题,分析了测角误差的成因和影响因素,结合实际采用了一种综合误差校正方法并进行了仿真分析. 仿真结果表明,该方法能够有效地解决误差,并在低信噪比条件下显示出了良好的性能,具有较高的可靠性.

  3. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  4. Calibration uncertainty

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Anglov, Thomas

    2002-01-01

    uncertainty was verified from independent measurements of the same sample by demonstrating statistical control of analytical results and the absence of bias. The proposed method takes into account uncertainties of the measurement, as well as of the amount of calibrant. It is applicable to all types......Methods recommended by the International Standardization Organisation and Eurachem are not satisfactory for the correct estimation of calibration uncertainty. A novel approach is introduced and tested on actual calibration data for the determination of Pb by ICP-AES. The improved calibration...

  5. Test and Calibration Metjods for X-band Active Pjased-array Weatjer Radar%X 波段一维扫描有源相控阵天气雷达测试定标方法

    Institute of Scientific and Technical Information of China (English)

    刘黎平; 吴翀; 汪旭东; 葛润生

    2015-01-01

    该文根据有源相控阵天气雷达的体制特点,参考多普勒天气雷达测试定标方法,提出了一维扫描有源相控阵天气雷达的测试和定标方法,将测试重点放在天馈系统、T/R 组件、脉冲压缩、动态范围的测试和定标上,以解决不同观测模式、不同波位的天线增益等参数变化引起的回波强度测量误差问题。测试结果表明:天馈系统在不同观测模式下的天线参数随仰角的变化情况、波束指向的准确度、T/R 组件的动态范围等均符合设计要求,回波强度和径向速度定标精度较高。雷达经过测试和定标后,于2014年5—8月分别在安徽定远和四川甘孜进行外场试验,并与附近多普勒天气雷达(SA)和 C 波段双线偏振雷达观测数据进行对比,结果表明:回波强度误差在合理范围内,精细测量、警戒搜索、快速观测3种模式观测的强回波的水平和垂直位置、结构和系统误差均比较一致,数据可靠。%A mobile X-band phased-array meteorological radar (XPAR)is developed by State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,and Anhui Sun-create Electronics Limited Company.The XPAR scans electronically in elevation while scanning mechanically in azimuth,transmits radar wave with wide beam width (about 20°in vertical direction and 1°in horizontal direction)and re-ceives 14 beams simultaneously.As reflectivity calibration is key technique for the active phased-array ra-dar application in meteorological observation,the testing and calibrating method for the XPAR is investi-gated according to characteristics of the transmitter/receiver (T/R)the multi-beam work mode.The test and calibration focus on the antennas,T/R,purse compress and the variations of gain and beam width with the angle of the antenna beam in respect to the normal of the array face,in order to reduce the obser-vation bias introduced by different modes

  6. RSS Feeds

    Science.gov (United States)

    ... www.nlm.nih.gov/medlineplus/rss.html RSS Feeds To use the sharing features on this page, ... NLM RSS Feeds and Podcasts . General Interest RSS Feeds What's New: MedlinePlus Announcements and Special Features The ...

  7. The Murchison Widefield Array

    CERN Document Server

    Mitchell, Daniel A; Ord, Stephen M; Bernardi, Gianni; Wayth, Randall B; Edgar, Richard G; Clark, Michael A; Dal, Kevin; Pfister, Hanspeter; Gleadow, Stewart J; Arcus, W; Briggs, F H; Benkevitch, L; Bowman, J D; Bunton, J D; Burns, S; Cappallo, R J; Corey, B E; de Oliveira-Costa, A; Desouza, L; Doeleman, S S; Derome, M F; Emrich, D; Glossop, M; Goeke, R; Krishna, M R Gopala; Hazelton, B; Herne, D E; Hewitt, J N; Kamini, P A; Kaplan, D L; Kasper, J C; Kincaid, B B; Kocz, J; Kowald, E; Kratzenberg, E; Kumar, D; Lonsdale, C J; Lynch, M J; Madhavi, S; Matejek, M; McWhirter, S R; Morales, M F; Morgan, E; Oberoi, D; Pathikulangara, J; Prabu, T; Rogers, A; Salah, J E; Sault, R J; Shankar, N Udaya; Srivani, K S; Stevens, J; Tingay, S J; Vaccarella, A; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C

    2010-01-01

    It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imaging software, which is currently being used to process an FM-band survey of the entire southern sky.

  8. HAWC Timing Calibration

    CERN Document Server

    Huentemeyer, Petra; Dingus, Brenda

    2009-01-01

    The High-Altitude Water Cherenkov (HAWC) Experiment is a second-generation highsensitivity gamma-ray and cosmic-ray detector that builds on the experience and technology of the Milagro observatory. Like Milagro, HAWC utilizes the water Cherenkov technique to measure extensive air showers. Instead of a pond filled with water (as in Milagro) an array of closely packed water tanks is used. The event direction will be reconstructed using the times when the PMTs in each tank are triggered. Therefore, the timing calibration will be crucial for reaching an angular resolution as low as 0.25 degrees.We propose to use a laser calibration system, patterned after the calibration system in Milagro. Like Milagro, the HAWC optical calibration system will use ~1 ns laser light pulses. Unlike Milagro, the PMTs are optically isolated and require their own optical fiber calibration. For HAWC the laser light pulses will be directed through a series of optical fan-outs and fibers to illuminate the PMTs in approximately one half o...

  9. Development of Wide Band Feeds

    Science.gov (United States)

    Ujihara, H.; Ichikawa, R.

    2012-12-01

    Wide Band feeds are being developed at NICT, NAOJ, and some universities in Japan for VLBI2010, SKA, and MARBLE. SKA, the Square Kilometre Array, will comprise thousands of radio telescopes with square kilometer aperture size for radio astronomy. MARBLE consists of small portable VLBI stations developed at NICT and GSI in Japan. They all need wide band feeds with a greater than 1:10 frequency ratio. Thus we have been studying wide band feeds with dual linear polarization for these applications.

  10. Clustered Calibration: An Improvement to Radio Interferometric Direction Dependent Self-Calibration

    CERN Document Server

    Kazemi, Sanaz; Zaroubi, Saleem

    2013-01-01

    The new generation of radio synthesis arrays, such as LOFAR and SKA, have been designed to surpass existing arrays in terms of sensitivity, angular resolution and frequency coverage. This evolution has led to the development of advanced calibration techniques that ensure the delivery of accurate results at the lowest possible computational cost. However, the performance of such calibration techniques is still limited by the compact, bright sources in the sky, used as calibrators. It is important to have a bright enough source that is well distinguished from the background noise level in order to achieve satisfactory results in calibration. We present "clustered calibration" as a modification to traditional radio interferometric calibration, in order to accommodate faint sources that are almost below the background noise level into the calibration process. The main idea is to employ the information of the bright sources' measured signals as an aid to calibrate fainter sources that are nearby the bright sources...

  11. The Submillimeter Array Polarimeter

    OpenAIRE

    Marrone, Daniel P.; Rao, Ramprasad

    2008-01-01

    We describe the Submillimeter Array (SMA) Polarimeter, a polarization converter and feed multiplexer installed on the SMA. The polarimeter uses narrow-band quarter-wave plates to generate circular polarization sensitivity from the linearly-polarized SMA feeds. The wave plates are mounted in rotation stages under computer control so that the polarization handedness of each antenna is rapidly selectable. Positioning of the wave plates is found to be highly repeatable, better than 0.2 degrees. A...

  12. Design of 5.8 GHz dual-polarized microstrip antenna array with low-side lobe and series feed%5.8GHz串馈低副瓣双极化微带天线阵设计

    Institute of Scientific and Technical Information of China (English)

    冯理; 李树

    2011-01-01

    Design 5.8 GHz dual-polarized microstrip antenna array with low-side lobe and series feed,it is easy to be made, high gain, Its simulated sidelobe level is --18 dB, and the measured port1 S11 <-10 dB is 5.5-6.5 GHz,port2 S22 <-10 dB is 5.7-6.6 GHz, It is suitable for ISM frequency wireless communications system.%采用串联馈电方式设计了一种工作于5.8 GHz低副瓣八元微带天线阵,该天线易于制作,具有双线极化、高增益、窄波束特性,仿真旁瓣电平为-18 dB,实测垂直极化端口S11<-10 dB的带宽是5.5~6.5 GHz,水平极化端口S22<-10 dB的带宽是5.7~6.6 GHz,能较好地满足ISM频段无线通信系统的要求.

  13. Scientific Opinion on the safety and efficacy of iodine compounds (E2 as feed additives for all animal species: calcium iodate anhydrous, based on a dossier submitted by Calibre Europe SPRL/BVBA

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2013-02-01

    Full Text Available Calcium iodate anhydrous is considered a safe source of iodine for all animal species/categories when used up to the currently authorised maximum content of total iodine in complete feed, with the exception of horses and dogs, for which maximum tolerated levels are 3 and 4 mg I/kg complete feed, respectively. The limited data available on iodine tolerance in cats support a provisional tolerated level of 5 mg I/kg complete feed. Exposure of consumers was calculated in two scenarios applying the currently authorised maximum iodine contents in feed and reduced contents. The iodine content of food of animal origin, if produced taking account of the currently authorised maximum content of iodine in feed, would represent a substantial risk to high consumers. The risk would originate primarily from the consumption of milk and to a minor extent from eggs. The UL for adults (600 µg/day and for toddlers (200 µg/day would be exceeded by a factor of 2 and 4, respectively. If the authorised maximum iodine concentrations in feed for dairy cows and laying hens were reduced to 2 and 3 mg I/kg feed, respectively, the exposure of adult consumers would be below the UL. However, iodine intake in high-consuming toddlers would remain above the UL (1.6-fold. Calcium iodate is considered as irritant to the eye, skin and respiratory tract, and a dermal sensitiser. The exposure by inhalation should be avoided. The use of calcium iodate in animal nutrition is not expected to pose a risk to the environment. Calcium iodate is efficacious to meet animal iodine requirements. The FEEDAP Panel recommends that the maximum iodine contents in complete feed be reduced as follows: dairy cows and minor dairy ruminants, 2 mg I/kg; laying hens, 3 mg I/kg; horses, 3 mg I/kg; dogs, 4 mg I/kg; cats, 5 mg I/kg.

  14. Infinite Bandwidth : Long Slot Array Antenna

    NARCIS (Netherlands)

    Neto, A.; Lee, J.J.

    2005-01-01

    This work deals with the properties of a long slot array fed by an array of periodically located feeds spaced at a Nyquist interval. The study begins with the rigorous Green's function (GF) of a single long slot which was extended to an infinite array structure. After this, the input impedance prope

  15. NuSTAR ground calibration: The Rainwater Memorial Calibration Facility (RaMCaF)

    DEFF Research Database (Denmark)

    Brejnholt, Nicolai; Christensen, Finn Erland; Jakobsen, Anders Clemen;

    2011-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5-80 keV ) telescope to orbit. The ground calibration of the three flight optics was carried out at the Rainwater Memorial Calibration Facility (RaMCaF) built for this...... purpose. In this article we present the facility and its use for the ground calibration of the three optics....

  16. Instrument calibration architecture of Radar Imaging Satellite (RISAT-1)

    Science.gov (United States)

    Misra, T.; Bhan, R.; Putrevu, D.; Mehrotra, P.; Nandy, P. S.; Shukla, S. D.; Rao, C. V. N.; Dave, D. B.; Desai, N. M.

    2016-05-01

    Radar Imaging Satellite (RISAT-1) payload system is configured to perform self-calibration of transmit and receive paths before and after imaging sessions through a special instrument calibration technique. Instrument calibration architecture of RISAT-1 supported ground verification and validation of payload including active array antenna. During on-ground validation of 126 beams of active array antenna which needed precise calibration of boresight pointing, a unique method called "collimation coefficient error estimation" was utilized. This method of antenna calibration was supported by special hardware and software calibration architecture of RISAT-1. This paper concentrates on RISAT-1 hardware and software architecture which supports in-orbit and on-ground instrument calibration. Efforts are also put here to highlight use of special calibration scheme of RISAT-1 instrument to evaluate system response during ground verification and validation.

  17. Orthogonal feeding techniques for tapered slot antennas

    Science.gov (United States)

    Lee, Richard Q.; Simons, Rainee N.

    1998-01-01

    For array of "brick" configuration there are electrical and mechanical advantages to feed the antenna with a feed on a substrate perpendicular to the antenna substrate. Different techniques have been proposed for exciting patch antennas using such a feed structure.Rncently, an aperture-coupled dielectric resonator antenna using a perpendicular feed substrate has been demonstrated to have very good power coupling efficiency. For a two-dimensional rectangular array with tapered slot antenna elements, a power combining network on perpendicular substrate is generally required to couple power to or from the array. In this paper, we will describe two aperture-coupled techniques for coupling microwave power from a linearly tapered slot antenna (LTSA) to a microstrip feed on a perpendicular substrate. In addition, we will present measured results for return losses and radiation patterns.

  18. Calibration Techniques for VERITAS

    CERN Document Server

    Hanna, David

    2007-01-01

    VERITAS is an array of four identical telescopes designed for detecting and measuring astrophysical gamma rays with energies in excess of 100 GeV. Each telescope uses a 12 m diameter reflector to collect Cherenkov light from air showers initiated by incident gamma rays and direct it onto a `camera' comprising 499 photomultiplier tubes read out by flash ADCs. We describe here calibration methods used for determining the values of the parameters which are necessary for converting the digitized PMT pulses to gamma-ray energies and directions. Use of laser pulses to determine and monitor PMT gains is discussed, as are measurements of the absolute throughput of the telescopes using muon rings.

  19. Sky reconstruction for the Tianlai cylinder array

    CERN Document Server

    Zhang, Jiao; Ansari, Reza; Chen, Xuelei; Li, Yichao; Wu, Fengquan; Campagne, Jean-Eric; Magneville, Christophe

    2016-01-01

    In this paper, we apply our sky map reconstruction method for transit type interferometers to the Tianlai cylinder array. The method is based on the spherical harmonic decomposition, and can be applied to cylindrical array as well as dish arrays and we can compute the instrument response, synthesised beam, transfer function and the noise power spectrum. We consider cylinder arrays with feed spacing larger than half wavelength, and as expected, we find that the arrays with regular spacing have grating lobes which produce spurious images in the reconstructed maps. We show that this problem can be overcome, using arrays with different feed spacing on each cylinder. We present the reconstructed maps, and study the performance in terms of noise power spectrum, transfer function and beams for both regular and irregular feed spacing configurations.

  20. The modelling of plane curvilinear dipole antenna arrays

    OpenAIRE

    Hoblyk, Viktor V.; Liske, O. M.; Yakovenko, Eugenia I.

    2005-01-01

    In this work the results of mathematical model design for printed dipole antenna arrays are presented. The arrays are feeding by curvilinear  transmission slotline. The investigation is important for the antenna arrays theory and useful for the design of antenna arrays with improved characteristics.

  1. Calibrating Images from the MINERVA Cameras

    Science.gov (United States)

    Mercedes Colón, Ana

    2016-01-01

    The MINiature Exoplanet Radial Velocity Array (MINERVA) consists of an array of robotic telescopes located on Mount Hopkins, Arizona with the purpose of performing transit photometry and spectroscopy to find Earth-like planets around Sun-like stars. In order to make photometric observations, it is necessary to perform calibrations on the CCD cameras of the telescopes to take into account possible instrument error on the data. In this project, we developed a pipeline that takes optical images, calibrates them using sky flats, darks, and biases to generate a transit light curve.

  2. Substrate integrated antennas and arrays

    CERN Document Server

    Cheng, Yu Jian

    2015-01-01

    Substrate Integrated Antennas and Arrays provides a single source for cutting-edge information on substrate integrated circuits (SICs), substrate integrated waveguide (SIW) feeding networks, SIW slot array antennas, SIC traveling-wave antennas, SIW feeding antennas, SIW monopulse antennas, and SIW multibeam antennas. Inspired by the author's extensive research, this comprehensive book:Describes a revolutionary SIC-based antenna technique with the potential to replace existing antenna technologiesExamines theoretical and experimental results connected to electrical and mechanical performanceExp

  3. Bandwidth Reconfigurable Metamaterial Arrays

    Directory of Open Access Journals (Sweden)

    Nathanael J. Smith

    2014-01-01

    Full Text Available Metamaterial structures provide innovative ways to manipulate electromagnetic wave responses to realize new applications. This paper presents a conformal wideband metamaterial array that achieves as much as 10 : 1 continuous bandwidth. This was done by using interelement coupling to concurrently achieve significant wave slow-down and cancel the inductance stemming from the ground plane. The corresponding equivalent circuit of the resulting array is the same as that of classic metamaterial structures. In this paper, we present a wideband Marchand-type balun with validation measurements demonstrating the metamaterial (MTM array’s bandwidth from 280 MHz to 2800 MHz. Bandwidth reconfiguration of this class of array is then demonstrated achieving a variety of band-pass or band-rejection responses within its original bandwidth. In contrast with previous bandwidth and frequency response reconfigurations, our approach does not change the aperture’s or ground plane’s geometry, nor does it introduce external filtering structures. Instead, the new responses are realized by making simple circuit changes into the balanced feed integrated with the wideband MTM array. A variety of circuit changes can be employed using MEMS switches or variable lumped loads within the feed and 5 example band-pass and band-rejection responses are presented. These demonstrate the potential of the MTM array’s reconfiguration to address a variety of responses.

  4. Traceable Pyrgeometer Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Dooraghi, Mike; Kutchenreiter, Mark; Reda, Ibrahim; Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Newman, Martina

    2016-05-02

    This poster presents the development, implementation, and operation of the Broadband Outdoor Radiometer Calibrations (BORCAL) Longwave (LW) system at the Southern Great Plains Radiometric Calibration Facility for the calibration of pyrgeometers that provide traceability to the World Infrared Standard Group.

  5. Multi-analyst, multi-matrix performance of the QuEChERS approach for pesticide residues in foods and feeds using HPLC/MS/MS analysis with different calibration techniques.

    Science.gov (United States)

    Lehotay, Steven J; Mastovska, Katerina; Lightfield, Alan R; Gates, Robert A

    2010-01-01

    Three different calibration approaches were applied in HPLC/MS/MS using electrospray ionization for the determination of 14 diverse pesticide residues at different levels in a variety of food matrixes. This study was conducted as part of a 4 day training course for 17 chemists to learn the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) approach to pesticide residue analysis in foods. The analysts were divided into four different teams for the analysis of 12 different matrixes (strawberries, plums, carrots, green peppers, milk, molasses, alfalfa oats, corn silage, dry pet food, soybean, almonds, and foliage). The acetate-buffered QuEChERS protocol gave excellent results in the spiked samples for all matrixes tested. The HPLC/MS/MS calibration techniques consisted of external standardization in solvent solutions, matrix-matching, and the echo-peak technique. Peak areas were normalized to an internal standard in all three approaches. Matrix effects were observed with the corn silage, carrot, and foliage extracts, but they were minimal or nonexistent in the other matrixes. Matrix-matching best compensated for matrix effects, but has logistical difficulties in real-world application and required extra sample preparation compared to the other approaches. The echo-peak technique reduced matrix effects but did not eliminate them. PMID:20480880

  6. The Australian Square Kilometre Array Pathfinder: System Architecture and Specifications of the Boolardy Engineering Test Array

    OpenAIRE

    Hotan, A. W.; Bunton, J. D.; Harvey-Smith, L.; Humphreys, B.; Jeffs, B. D.; Shimwell, T.; Tuthill, J.; Voronkov, M.; G. Allen; Amy, S.; Ardern, K.; Axtens, P.; Ball, L; Bannister, K.; Barker, S.

    2014-01-01

    This paper describes the system architecture of a newly constructed radio telescope - the Boolardy Engineering Test Array, which is a prototype of the Australian Square Kilometre Array Pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a 6-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least 9 dual-pola...

  7. Dense Focal Plane Arrays for Pushbroom Satellite Radiometers

    DEFF Research Database (Denmark)

    Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.;

    2014-01-01

    Performance of a dense focal plane array feeding an offset toroidal reflector antenna system is studied and discussed in the context of a potential application in multi-beam radiometers for ocean surveillance. We present a preliminary design of the array feed for the 5-m diameter antenna at X...

  8. Spherical Horn Array for Wideband Propagation Measurements

    DEFF Research Database (Denmark)

    Franek, Ondrej; Pedersen, Gert Frølund

    2011-01-01

    A spherical array of horn antennas designed to obtain directional channel information and characteristics is introduced. A dual-polarized quad-ridged horn antenna with open flared boundaries and coaxial feeding for the frequency band 600 MHz–6 GHz is used as the element of the array. Matching...

  9. Long Slot Arrays - Part 1: Theoretical Formulation

    NARCIS (Netherlands)

    Neto, A.; Lee, J.J.

    2005-01-01

    This work deals with the properties of an array of long slots fed by periodically located feed elements spaced at Nyquist interval. The presentation is structured in two parts. This first part introduces the theoretical formulation of the problem and the input impedance properties of the array when

  10. Radio Frequency Optics Design of the 12-Meter Antenna for the Array-Based Deep Space Network

    Science.gov (United States)

    Imbriale, W. A.

    2005-02-01

    Development of very large arrays of small antennas has been proposed as a way to increase the downlink capability of the NASA Deep Space Network (DSN) by two or three orders of magnitude, thereby enabling greatly increased science data from currently configured missions or enabling new mission concepts. The current concept is for an array of 400 x 12-meter antennas at each of three longitudes. The DSN array will utilize radio astronomy sources for phase calibration and will have wide bandwidth correlation processing for this purpose. JPL currently is building a 3-element interferometer composed of 6-meter antennas to prove the performance and cost of the DSN array. This article describes the radio frequency (RF) design of the 12-meter reflector that will use the same feed and electronics as the 6-meter antenna. The 6-meter antenna utilized Gregorian optics to enable tests with a low-frequency prime focus feed without removing the subreflector. However, for the 12-meter antenna, maximum gain divided by noise temperature (G/T) is the overriding requirement, and a trade-off study demonstrated that Cassegrain optics is far superior to Gregorian optics for maximum G/T. Hence, the 12-meter antenna utilizes Cassegrain optics.

  11. An Ultra-Wideband Millimeter-Wave Phased Array

    Science.gov (United States)

    Novak, Markus H.; Miranda, Felix A.; Volakis, John L.

    2016-01-01

    Wideband millimeter-wave arrays are of increasing importance due to their growing use in high data rate systems, including 5G communication networks. In this paper, we present a new class of ultra-wideband millimeter wave arrays that operate from nearly 20 GHz to 90 GHz. The array is based on tightly coupled dipoles. Feeding designs and fabrication challenges are presented, and a method for suppressing feed resonances is provided.

  12. DOA estimation and mutual coupling calibration with the SAGE algorithm

    Directory of Open Access Journals (Sweden)

    Xiong Kunlai

    2014-12-01

    Full Text Available In this paper, a novel algorithm is presented for direction of arrival (DOA estimation and array self-calibration in the presence of unknown mutual coupling. In order to highlight the relationship between the array output and mutual coupling coefficients, we present a novel model of the array output with the unknown mutual coupling coefficients. Based on this model, we use the space alternating generalized expectation-maximization (SAGE algorithm to jointly estimate the DOA parameters and the mutual coupling coefficients. Unlike many existing counterparts, our method requires neither calibration sources nor initial calibration information. At the same time, our proposed method inherits the characteristics of good convergence and high estimation precision of the SAGE algorithm. By numerical experiments we demonstrate that our proposed method outperforms the existing method for DOA estimation and mutual coupling calibration.

  13. DOA estimation and mutual coupling calibration with the SAGE algorithm

    Institute of Scientific and Technical Information of China (English)

    Xiong Kunlai; Liu Zhangmeng; Liu Zheng; Jiang Wenli

    2014-01-01

    In this paper, a novel algorithm is presented for direction of arrival (DOA) estimation and array self-calibration in the presence of unknown mutual coupling. In order to highlight the relationship between the array output and mutual coupling coefficients, we present a novel model of the array output with the unknown mutual coupling coefficients. Based on this model, we use the space alternating generalized expectation-maximization (SAGE) algorithm to jointly estimate the DOA parameters and the mutual coupling coefficients. Unlike many existing counterparts, our method requires neither calibration sources nor initial calibration information. At the same time, our proposed method inherits the characteristics of good convergence and high estimation precision of the SAGE algorithm. By numerical experiments we demonstrate that our proposed method outperforms the existing method for DOA estimation and mutual coupling calibration.

  14. Trinocular Calibration Method Based on Binocular Calibration

    Directory of Open Access Journals (Sweden)

    CAO Dan-Dan

    2012-10-01

    Full Text Available In order to solve the self-occlusion problem in plane-based multi-camera calibration system and expand the measurement range, a tri-camera vision system based on binocular calibration is proposed. The three cameras are grouped into two pairs, while the public camera is taken as the reference to build the global coordinate. By calibration of the measured absolute distance and the true absolute distance, global calibration is realized. The MRE (mean relative error of the global calibration of the two camera pairs in the experiments can be as low as 0.277% and 0.328% respectively. Experiment results show that this method is feasible, simple and effective, and has high precision.

  15. FEED FORMULATION AND FEEDING TECHNOLOGY FOR FISHES

    Directory of Open Access Journals (Sweden)

    Govind Pandey

    2013-03-01

    Full Text Available Most fish farmers and ornamental fish hobbyists buy the bulk of their feed from commercial manufacturers. However, small quantities of specialized feeds are often needed for experimental purposes, feeding difficult-to maintain aquarium fishes, larval or small juvenile fishes, brood fish conditioning, or administering medication to sick fish. Small ornamental fish farms with an assortment of fish require small amounts of various diets with particular ingredients. It is not cost effective for commercial manufacturers to produce very small quantities of specialized feeds. Most feed mills will only produce custom formulations in quantities of more than one ton, and medicated feeds are usually sold in 50-pound bags. Small fish farmers, hobbyists and laboratory technicians are, therefore, left with the option of buying large quantities of expensive feed, which often goes to waste. Small quantities of fish feeds can be made quite easily in the laboratory, classroom, or at home, with common ingredients and simple kitchen or laboratory equipment. Hence, this review provides the knowledge about the fish feed formulation and feeding technology concerned with the live feed for fish larvae, fish feeds, fish feed ingredients, common fish feed stuffs, animal and plant sources of feeds for culture fish, and fish feeding methods.

  16. ORNL calibrations facility

    International Nuclear Information System (INIS)

    The ORNL Calibrations Facility is operated by the Instrumentation Group of the Industrial Safety and Applied Health Physics Division. Its primary purpose is to maintain radiation calibration standards for calibration of ORNL health physics instruments and personnel dosimeters. This report includes a discussion of the radioactive sources and ancillary equipment in use and a step-by-step procedure for calibration of those survey instruments and personnel dosimeters in routine use at ORNL

  17. Array tomography: imaging stained arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time-consuming and require some practice to perfect. In this protocol, tissue arrays are imaged using conventional wide-field fluorescence microscopy. Images can be captured manually or, with the appropriate software and hardware, the process can be automated. PMID:21041399

  18. Array tomography: production of arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time consuming and require some practice to perfect. This protocol describes the sectioning of embedded tissues and the mounting of the serial arrays. The procedures require some familiarity with the techniques used for ultramicrotome sectioning for electron microscopy. PMID:21041397

  19. Spiral reader calibration

    International Nuclear Information System (INIS)

    The method to calibrate the spiral reader (SR) is presented. A brief description of the main procedures of the calibration program SCALP, adapted for the IHEP equipment and purposes, is described. The precision characteristics of the IHEP SR have been analysed on the results, presented in the form of diagrams. There is a calibration manual for the user

  20. Time calibration of the ANTARES neutrino telescope

    International Nuclear Information System (INIS)

    The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of 1 ns. The methods developed to attain this level of precision are described. (authors)

  1. The NSLS 100 element solid state array detector

    International Nuclear Information System (INIS)

    X-ray absorption studies of dilute samples require fluorescence detection techniques. Since signal-to-noise ratios are governed by the ratio of fluorescent to scattered photons counted by a detector, solid state detectors which can discriminate between fluorescence and scattered photons have become the instruments of choice for trace element measurements. Commercially available 13 element Ge array detectors permitting total count rates < 500 000 counts per second are now in routine use. Since X-ray absorption beamlines at high brightness synchrotron sources can already illuminate most dilute samples with enough flux to saturate the current generation of solid state detectors, the development of next-generation instruments with significantly higher total count rates is essential. We present the design and current status of the 100 elements Si array detector being developed in a collaboration between the NSLS and the Instrumentation Division at Brookhaven National Laboratory. The detecting array consists of a 10 x 10 matrix of 4 mm x 4 mm elements laid out on a single piece of ultrahigh purity silicon mounted at the front end of a liquid nitrogen dewar assembly. A matrix of charge sensitive integrating preamplifiers feed signals to an array of shaping amplifiers, single channel analyzers, and scalers. An electronic switch, delay amplifier, linear gate, digital scope, peak sensing A/D converter, and histogramming memory module provide for complete diagnostics and channel calibration. The entrie instrument is controlled by a LabView 2 application on a MacII ci; the software also provides full control over beamline hardware and performs the data collection. (orig.)

  2. Residual gas analyzer calibration

    Science.gov (United States)

    Lilienkamp, R. H.

    1972-01-01

    A technique which employs known gas mixtures to calibrate the residual gas analyzer (RGA) is described. The mass spectra from the RGA are recorded for each gas mixture. This mass spectra data and the mixture composition data each form a matrix. From the two matrices the calibration matrix may be computed. The matrix mathematics requires the number of calibration gas mixtures be equal to or greater than the number of gases included in the calibration. This technique was evaluated using a mathematical model of an RGA to generate the mass spectra. This model included shot noise errors in the mass spectra. Errors in the gas concentrations were also included in the valuation. The effects of these errors was studied by varying their magnitudes and comparing the resulting calibrations. Several methods of evaluating an actual calibration are presented. The effects of the number of gases in then, the composition of the calibration mixture, and the number of mixtures used are discussed.

  3. Prediction of cereal feed value using spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Jørgensen, Johannes Ravn; Gislum, René

    2009-01-01

    Feed value in form of FEsv (Feed unit / kg dry matter, for piglets) and FEso (Feed unit / kg dry matter, for sows), EDOM (Enzyme Degradable Organic Matter) and EDOMi (Enzyme Degradable Organic Matter, Ileum) is used in the feed evaluation system for pigs. Analysis of feed value have highlighted...... of EDOM, EDOMi, FEso and FEsv. The outcome of a successful NIRS calibration will be a relatively cheap tool to monitor, diversify and evaluate the quality of cereals for animal feed, a possible tool to assess the feed value of new varieties in the variety testing and a useful, cheap and rapid tool...... for cereal breeders. A collection of 1213 grain samples of wheat, triticale, barley and rye, and related chemical reference analyses to describe the feed value have been established. The samples originate from available field trials over a three-year period. The chemical reference analyses are dry matter...

  4. The self-cohering tied-array

    CERN Document Server

    Fridman, P A

    2010-01-01

    Large radio astronomy multi-element interferometers are frequently used as single dishes in a tied-array mode when signals from separate antennas are added. Phase shifts arising during wave propagation through a turbulent atmosphere can significantly reduce the effective area of an equivalent single dish. I aim to give estimates of the impact of the ionosphere and troposphere on the effectiveness of a radio interferometer working in tied-array mode. Statistical estimates of the effective area are calculated and the power-law of turbulent atmosphere irregularities has been used. A simple method of tied-array calibration using optimization techniques is proposed. The impact of phase errors on the effectiveness of tied-arrays are given for low and high frequencies. Computer simulations demonstrate the efficacy of the proposed calibration algorithm.

  5. Radiometric Calibration for AgCam

    OpenAIRE

    Edward Hildum; Lianbo Hu; Hojin Kim; Xiaodong Zhang; Changyong Dou; Doug Olsen

    2010-01-01

    The student-built Agricultural Camera (AgCam) now onboard the International Space Station observes the Earth surface through two linescan cameras with Charge-Coupled Device (CCD) arrays sensitive to visible and near-infrared wavelengths, respectively. The electro-optical components of the AgCam were characterized using precision calibration equipment; a method for modeling and applying these measurements was derived. Correction coefficients to minimize effects of optical vignetting, CCD non-u...

  6. In-line X-slot element focal plane array of kinetic inductance detectors

    NARCIS (Netherlands)

    Iacono, A.; Freni, A.; Neto, A.; Gerini, G.

    2011-01-01

    Kinetic Inductance Detectors are very promising THz imaging devices to be used in Focal Plane Array configuration. In this work a new antenna feed element has been studied and optimized. Preliminary results on array configuration are also shown.

  7. CCD camera automatic calibration technology and ellipse recognition algorithm

    Institute of Scientific and Technical Information of China (English)

    Changku Sun; Xiaodong Zhang; Yunxia Qu

    2005-01-01

    A novel two-dimensional (2D) pattern used in camera calibration is presented. With one feature circle located at the center, an array of circles is photo-etched on this pattern. An ellipse recognition algorithm is proposed to implement the acquisition of interest calibration points without human intervention. According to the circle arrangement of the pattern, the relation between three-dimensional (3D) and 2D coordinates of these points can be established automatically and accurately. These calibration points are computed for intrinsic parameters calibration of charge-coupled device (CCD) camera with Tsai method. A series of experiments have shown that the algorithm is robust and reliable with the calibration error less than 0.4 pixel. This new calibration pattern and ellipse recognition algorithm can be widely used in computer vision.

  8. Breastfeeding vs. Formula Feeding

    Science.gov (United States)

    ... Things to Know About Zika & Pregnancy Breastfeeding vs. Formula Feeding KidsHealth > For Parents > Breastfeeding vs. Formula Feeding ... with a lactation specialist. previous continue All About Formula Feeding Commercially prepared infant formulas are a nutritious ...

  9. The External Calibrator for Hydrogen Observatories

    CERN Document Server

    Jacobs, Daniel C; Bowman, Judd; Neben, Abraham R; Stinnett, Benjamin; Turner, Lauren

    2016-01-01

    Multiple instruments are pursuing constraints on dark energy, observing reionization and opening a window on the dark ages through the detection and characterization of the 21cm hydrogen line across the redshift spectrum, from nearby to z=25. These instruments, including CHIME in the sub-meter and HERA in the meter bands, are wide-field arrays with multiple-degree beams, typically operating in transit mode. Accurate knowledge of their primary beams is critical for separation of bright foregrounds from the desired cosmological signals, but difficult to achieve through astronomical observations alone. Previous beam calibration work has focused on model verification and does not address the need of 21cm experiments for routine beam mapping, to the horizon, of the as-built array. We describe the design and methodology of a drone-mounted calibrator, the External Calibrator for Hydrogen Observatories (ECHO), that aims to address this need. We report on a first set of trials to calibrate low-frequency dipoles and co...

  10. Calibration and optimization of proportional counter modules using Garfield

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kiwhan [Los Alamos National Laboratory; Brockwell, Michael I [Los Alamos National Laboratory; Borozdin, Konstantin N [Los Alamos National Laboratory; Green, J Andrew [Los Alamos National Laboratory; Hogan, Gary E [Los Alamos National Laboratory; Makela, Mark F [Los Alamos National Laboratory; Mariam, Fesseha G [Los Alamos National Laboratory; Morris, Christopher L [Los Alamos National Laboratory

    2010-01-01

    Prototypes of radiation detector arrays used for charged-particle radiography require iniliol calibration to correlate the distribution of electron arrival time to the particle track locations. This step is crucial to obtaining the spatial resolution necessary to separate particle tracks traversing the individual proportional counters in the arrays. Our past attempts to use cosmic rays alone for the initial calibration have fallen short of obtaining the desired resolution due to the insufficient cosmic ray flux to provide the necessary number of particle tracks. A theoretical relation between electron drift time and radial drift distance is obtained with Garfield, a CERN gas detector simulation program. This relation is then used as an effective starting point for the initial calibration and results in a shorter calibration period and improved spatial resolution of the detectors.

  11. Absolute angular calibration of a submarine km3 neutrino telescope

    International Nuclear Information System (INIS)

    A requirement for neutrino telescope is the ability to resolve point sources of neutrinos. In order to understand its resolving power a way to perform absolute angular calibration with muons is required. Muons produced by cosmic rays in the atmosphere offer an abundant calibration source. By covering a surface vessel with 200 modules of 5 m2 plastic scintillator a surface air shower array can be set up. Running this array in coincidence with a deep-sea km3 size neutrino detector, where the coincidence is defined by the absolute clock timing stamp for each event, would allow absolute angular calibration to be performed. Monte Carlo results simulating the absolute angular calibration of the km3 size neutrino detector will be presented. Future work and direction will be discussed.

  12. USE OF FEED YEAST IN FEEDING OF STURGEON (ACIPENSERINAE SPECIES (REVIEW

    Directory of Open Access Journals (Sweden)

    M. Simon

    2015-12-01

    Full Text Available Purpose. To review scientific sources on the use of feed yeast preparations in feeding of sturgeon species (Acipenserinae. Findings. The review of scientific works demonstrated that feed yeast in the feeding of sturgeons have been used as a source of vitamins and complete protein, the nutritional value of which is significantly higher than in the proteins of plant origin and are similar to the proteins of animal origin. In addition, a unit of yeast protein mass is significantly lower than in the feeds of animal origin. Moreover, based on the content of B group vitamins, feed yeast produced from the grain-potato spent wash exceed fish meal and meat-and-bone meal. The article highlights the peculiarities of the technological process of the production of different feed yeast species, amino acid and fatty acid composition of their preparations, basic physical and chemical parameters of their composition. The examples of feed yeast formulas for sturgeon species based on feed yeast preparations are presented. It was shown that sturgeon species, especially on early stages of their ontogenesis, could effectively use the feed yeast nucleotides. Thus, the latters can be an effective substitute of live zooplanktonic organisms. While the production of some feed yeast preparations (paprin, eprin was stopped in 1990s due to a number of social-economic reasons, the works on the creation of their full analogues was continued later. Currently, the trends of the development of world aquaculture anticipates the return to the use of yeast in fish feeding. Therefore, the interest of the agrarians of Ukraine in yeast lately increased and their use in agricultural sector increased by 2-2.5 times. Practical value. The array of the summarized information will be important for scientists who study the peculiarities of feeding of sturgeon species, because the data about the use of yeast as sources of complete protein in fish feeds is important in a constant search for the

  13. Calibration of High Frequency MEMS Microphones

    Science.gov (United States)

    Shams, Qamar A.; Humphreys, William M.; Bartram, Scott M.; Zuckewar, Allan J.

    2007-01-01

    Understanding and controlling aircraft noise is one of the major research topics of the NASA Fundamental Aeronautics Program. One of the measurement technologies used to acquire noise data is the microphone directional array (DA). Traditional direction array hardware, consisting of commercially available condenser microphones and preamplifiers can be too expensive and their installation in hard-walled wind tunnel test sections too complicated. An emerging micro-machining technology coupled with the latest cutting edge technologies for smaller and faster systems have opened the way for development of MEMS microphones. The MEMS microphone devices are available in the market but suffer from certain important shortcomings. Based on early experiments with array prototypes, it has been found that both the bandwidth and the sound pressure level dynamic range of the microphones should be increased significantly to improve the performance and flexibility of the overall array. Thus, in collaboration with an outside MEMS design vendor, NASA Langley modified commercially available MEMS microphone as shown in Figure 1 to meet the new requirements. Coupled with the design of the enhanced MEMS microphones was the development of a new calibration method for simultaneously obtaining the sensitivity and phase response of the devices over their entire broadband frequency range. Over the years, several methods have been used for microphone calibration. Some of the common methods of microphone calibration are Coupler (Reciprocity, Substitution, and Simultaneous), Pistonphone, Electrostatic actuator, and Free-field calibration (Reciprocity, Substitution, and Simultaneous). Traditionally, electrostatic actuators (EA) have been used to characterize air-condenser microphones for wideband frequency ranges; however, MEMS microphones are not adaptable to the EA method due to their construction and very small diaphragm size. Hence a substitution-based, free-field method was developed to

  14. Automatic energy calibration of germanium detectors using fuzzy set theory

    International Nuclear Information System (INIS)

    With the advent of multi-detector arrays, many tasks that are usually performed by physicists, such as energy calibration, become very time consuming. There is therefore a need to develop more and more complex algorithms able to mimic human expertise. Fuzzy logic proposes a theoretical framework to build algorithms that are close to the human way of thinking. In this paper we apply fuzzy set theory in order to develop an automatic procedure for energy calibration. The algorithm, based on fuzzy concepts, has been tested on data taken with the EUROBALL IV γ-ray array

  15. Study of the calibration potential of HELYCON detectors with ANTARES

    Energy Technology Data Exchange (ETDEWEB)

    Ernenwein, Jean-Pierre [Universite de Haute Alsace, 61 rue Albert Camus, F68100 Mulhouse (France)], E-mail: ernenwein@cppm.in2p3.fr; Tsirigotis, Apostolos; Tzamarias, Spyros [School of Science and Technology, Hellenic Open University, Tsamadou 13-15 and Aghiou Andrea, Patras 26222 (Greece)

    2009-04-11

    The 'HEllenic LYceum Cosmic Observatories Network' (HELYCON) Collaboration is constructing a network of detector stations dedicated to the study of Extensive Air Showers. The use of HELYCON detectors is also envisaged for the calibration of a cubic kilometer scale Mediterranean neutrino telescope by means of an array of these detectors at the sea surface. The ANTARES framework is well suited to perform a first test of the principle: a feasibility study is on-going and a test in real conditions is foreseen. In this paper the requirements for evaluating the calibration potential of a surface array in the ANTARES context are discussed.

  16. OLI Radiometric Calibration

    Science.gov (United States)

    Markham, Brian; Morfitt, Ron; Kvaran, Geir; Biggar, Stuart; Leisso, Nathan; Czapla-Myers, Jeff

    2011-01-01

    Goals: (1) Present an overview of the pre-launch radiance, reflectance & uniformity calibration of the Operational Land Imager (OLI) (1a) Transfer to orbit/heliostat (1b) Linearity (2) Discuss on-orbit plans for radiance, reflectance and uniformity calibration of the OLI

  17. The GERDA calibration system

    International Nuclear Information System (INIS)

    A system with three identical custom made units is used for the energy calibration of the GERDA Ge diodes. To perform a calibration the 228Th sources are lowered from the parking positions at the top of the cryostat. Their positions are measured by two independent modules. One, the incremental encoder, counts the holes in the perforated steel band holding the sources, the other measures the drive shaft's angular position even if not powered. The system can be controlled remotely by a Labview program. The calibration data is analyzed by an iterative calibration algorithm determining the calibration functions for different energy reconstruction algorithms and the resolution of several peaks in the 228Th spectrum is determined. A Monte Carlo simulation using the GERDA simulation software MAGE has been performed to determine the background induced by the sources in the parking positions.

  18. Sandia WIPP calibration traceability

    International Nuclear Information System (INIS)

    This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities

  19. Characterization of a dense aperture array for radio astronomy

    Science.gov (United States)

    Torchinsky, S. A.; Olofsson, A. O. H.; Censier, B.; Karastergiou, A.; Serylak, M.; Picard, P.; Renaud, P.; Taffoureau, C.

    2016-05-01

    EMBRACE@Nançay is a prototype instrument consisting of an array of 4608 densely packed antenna elements creating a fully sampled, unblocked aperture. This technology is proposed for the Square Kilometre Array and has the potential of providing an extremely large field of view making it the ideal survey instrument. We describe the system, calibration procedures, and results from the prototype.

  20. Characterization of a dense aperture array for radio astronomy

    CERN Document Server

    Torchinsky, S A; Censier, B; Karastergiou, A; Serylak, M; Picard, P; Renaud, P; Taffoureau, C

    2016-01-01

    EMBRACE@Nancay is a prototype instrument consisting of an array of 4608 densely packed antenna elements creating a fully sampled, unblocked aperture. This technology is proposed for the Square Kilometre Array and has the potential of providing an extremely large field of view making it the ideal survey instrument. We describe the system,calibration procedures, and results from the prototype.

  1. 用于空间功率合成的线阵馈电焦散抛物曲面天线%Linear array feed caustic parabolic curved antenna for spatial power combinating

    Institute of Scientific and Technical Information of China (English)

    谢泽明; 王立新; 阮水生

    2012-01-01

    提出了一种用于空间功率合成的焦散抛物曲面天线,该反射面天线是由xoz平面的一条抛物线沿着yoz平面上的另一条抛物线正交扫描所形成的,天线用8单元E面喇叭线阵进行偏馈。研究了天线的反射面结构参数对天线性能的影响以及横向偏焦电扫描特性,给出了不同辐射方向下阵列的相位配置公式。仿真和实验结果表明:提出的方案可以在给定方向合成高增益波束,与同样线阵馈电的抛物柱面天线相比,H面3dB波束宽度从8.2°下降到了5°,天线增益提高了2.2dB.%A caustic parabolic curved antenna for spatial power combination is proposed in this paper.The reflector antenna is formed by a parabola in the xoz plane orthogonal scanning along the other parabola in the yoz plane.And antenna is offset fed with a line array of 8 E-plane sector horns.Both the impact of antenna structural parameters to the antenna performance and the electric scanning properties of the transversal displacement from focus are studied.A formula is given to configure the phases of the array for a given beam deflection angle.Simulation and experiment show that the designed antenna can combine a high gain beam at a given direction.Compared with the parabolic cylindrical antenna with the same aperture,the H-plane 3 dB beam width decreases from 6.9° to 5°,and the antenna gain increases by 2.2 dB.

  2. FEED FORMULATION AND FEEDING TECHNOLOGY FOR FISHES

    OpenAIRE

    Govind Pandey

    2013-01-01

    Most fish farmers and ornamental fish hobbyists buy the bulk of their feed from commercial manufacturers. However, small quantities of specialized feeds are often needed for experimental purposes, feeding difficult-to maintain aquarium fishes, larval or small juvenile fishes, brood fish conditioning, or administering medication to sick fish. Small ornamental fish farms with an assortment of fish require small amounts of various diets with particular ingredients. It is not cost effective for c...

  3. Segment Based Camera Calibration

    Institute of Scientific and Technical Information of China (English)

    马颂德; 魏国庆; 等

    1993-01-01

    The basic idea of calibrating a camera system in previous approaches is to determine camera parmeters by using a set of known 3D points as calibration reference.In this paper,we present a method of camera calibration in whih camera parameters are determined by a set of 3D lines.A set of constraints is derived on camea parameters in terms of perspective line mapping.Form these constraints,the same perspective transformation matrix as that for point mapping can be computed linearly.The minimum number of calibration lines is 6.This result generalizes that of Liu,Huang and Faugeras[12] for camera location determination in which at least 8 line correspondences are required for linear computation of camera location.Since line segments in an image can be located easily and more accurately than points,the use of lines as calibration reference tends to ease the computation in inage preprocessing and to improve calibration accuracy.Experimental results on the calibration along with stereo reconstruction are reported.

  4. Mapping Capacitive Coupling Among Pixels in a Sensor Array

    Science.gov (United States)

    Seshadri, Suresh; Cole, David M.; Smith, Roger M.

    2010-01-01

    An improved method of mapping the capacitive contribution to cross-talk among pixels in an imaging array of sensors (typically, an imaging photodetector array) has been devised for use in calibrating and/or characterizing such an array. The method involves a sequence of resets of subarrays of pixels to specified voltages and measurement of the voltage responses of neighboring non-reset pixels.

  5. Redundant Array Configurations for 21 cm Cosmology

    CERN Document Server

    Dillon, Joshua S

    2016-01-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays--in which the same mode on the sky is sampled by many antenna pairs--for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA's can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both ins...

  6. Research of optimizing the microwave wide band blackbody calibration target

    Institute of Scientific and Technical Information of China (English)

    Nian Feng; Yang Yujie; Wang Wei

    2009-01-01

    The blackbody calibration targets applied for microwave radiometer's prelauneh calibration are opti-mized with its electromagnetic and thermal characteristics. Based on the method of emissivity optimization with radar cross section (RCS) simulation and the method of subgrid finite difference time domain (FDTD), the following design rules are summarized: that the round wedge is better than the square one, the best ratio from height to bottom radius is 4:1, for wide band calibration, the multilayer absorbing material coating is efficient to increase the emissivity, and the gradual thickness absorbing material coating is helpful to guarantee the uniform distribution of surface temperature even as it keeps a higher emissivity. Finally following the above conclusions, a new type of blackbody calibration target with the cellular array is preferred to improve the uniformity of polarization, which will increase the performance of the calibration targets further.

  7. Lidar Calibration Centre

    Science.gov (United States)

    Pappalardo, Gelsomina; Freudenthaler, Volker; Nicolae, Doina; Mona, Lucia; Belegante, Livio; D'Amico, Giuseppe

    2016-06-01

    This paper presents the newly established Lidar Calibration Centre, a distributed infrastructure in Europe, whose goal is to offer services for complete characterization and calibration of lidars and ceilometers. Mobile reference lidars, laboratories for testing and characterization of optics and electronics, facilities for inspection and debugging of instruments, as well as for training in good practices are open to users from the scientific community, operational services and private sector. The Lidar Calibration Centre offers support for trans-national access through the EC HORIZON2020 project ACTRIS-2.

  8. Equipment for dosemeter calibration

    International Nuclear Information System (INIS)

    The device is used for precise calibration of dosimetric instrumentation, such as used at nuclear facilities. The high precision of the calibration procedure is primarily due to the fact that one single and steady radiation source is used. The accurate alignment of the source and the absence of shielding materials in the beam axis make for high homogeneity of the beam and reproducibility of the measurement; this is also contributed to by the horizontal displacement of the optical bench, which ensures a constant temperature field and the possibility of adjusting the radiation source at a sufficient distance from the instrument to be calibrated. (Z.S.). 3 figs

  9. SPOTS Calibration Example

    Directory of Open Access Journals (Sweden)

    Patterson E.

    2010-06-01

    Full Text Available The results are presented using the procedure outlined by the Standardisation Project for Optical Techniques of Strain measurement to calibrate a digital image correlation system. The process involves comparing the experimental data obtained with the optical measurement system to the theoretical values for a specially designed specimen. The standard states the criteria which must be met in order to achieve successful calibration, in addition to quantifying the measurement uncertainty in the system. The system was evaluated at three different displacement load levels, generating strain ranges from 289 µstrain to 2110 µstrain. At the 289 µstrain range, the calibration uncertainty was found to be 14.1 µstrain, and at the 2110 µstrain range it was found to be 28.9 µstrain. This calibration procedure was performed without painting a speckle pattern on the surface of the metal. Instead, the specimen surface was prepared using different grades of grit paper to produce the desired texture.

  10. Traceable Pyrgeometer Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Dooraghi, Mike; Kutchenreiter, Mark; Reda, Ibrahim; Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Newman, Martina; Webb, Craig

    2016-05-02

    This presentation provides a high-level overview of the progress on the Broadband Outdoor Radiometer Calibrations for all shortwave and longwave radiometers that are deployed by the Atmospheric Radiation Measurement program.

  11. Air Data Calibration Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This facility is for low altitude subsonic altimeter system calibrations of air vehicles. Mission is a direct support of the AFFTC mission. Postflight data merge is...

  12. Tracking antenna architectures based on an integrated mixer microstrip patch array

    International Nuclear Information System (INIS)

    The object of this work is to design, develop and characterize both theoretically and experimentally a compact integrated mixer microstrip patch antenna which exhibits a low level of cross-polarization. Modelling of this antenna using various CAD techniques and supporting measurements has led to a clearer understanding of its operation and the optimization of its design. The attractiveness of such a frequency scaleable design lies in the inherent simplicity and ease with which it can be used to produce an intermediate frequency (IF) signal with minimum circuit complexity and low cross-polar levels. The operation of the integrated mixer antenna circuit is exploited under the phenomenon of injection locking for its potential for direct phase modulation and detection. It leads to new vistas of study such as IF phase-shifterless beam steering. Here the desired phased shift is derived through injection locking and achieved solely by the DC bias control, thus eliminating the need for phase shifters and feed networks. A self-tracking integrated mixer array has also been described which uses an in-band pilot carrier signal for self-calibration. By minor alteration of the integrated antenna topology, a minimum complexity variant of a heterodyne retrodirective array has then been realized. These tracking antenna architectures minimize the problems of cost, complexity and size limitations associated with conventional phased arrays. These are designed for emerging commercial applications and are resolutions of some trade-offs that balance performance, cost and reliability. Theoretical and experimental results are presented to show their performances and, in addition, the practical requirements relevant to these are also addressed. The results indicate that these tracking antenna architectures based on an integrated mixer microstrip patch array could form a synergistic link with other emerging technologies and can be to some extent embodied in future phased array designs

  13. Approximation Behooves Calibration

    DEFF Research Database (Denmark)

    da Silva Ribeiro, André Manuel; Poulsen, Rolf

    2013-01-01

    Calibration based on an expansion approximation for option prices in the Heston stochastic volatility model gives stable, accurate, and fast results for S&P500-index option data over the period 2005–2009.......Calibration based on an expansion approximation for option prices in the Heston stochastic volatility model gives stable, accurate, and fast results for S&P500-index option data over the period 2005–2009....

  14. Scanner calibration revisited

    Directory of Open Access Journals (Sweden)

    Pozhitkov Alexander E

    2010-07-01

    Full Text Available Abstract Background Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2. reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Methods Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. Results We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Conclusions Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides.

  15. Energy calibration via correlation

    CERN Document Server

    Maier, Daniel

    2015-01-01

    The main task of an energy calibration is to find a relation between pulse-height values and the corresponding energies. Doing this for each pulse-height channel individually requires an elaborated input spectrum with an excellent counting statistics and a sophisticated data analysis. This work presents an easy to handle energy calibration process which can operate reliably on calibration measurements with low counting statistics. The method uses a parameter based model for the energy calibration and concludes on the optimal parameters of the model by finding the best correlation between the measured pulse-height spectrum and multiple synthetic pulse-height spectra which are constructed with different sets of calibration parameters. A CdTe-based semiconductor detector and the line emissions of an 241 Am source were used to test the performance of the correlation method in terms of systematic calibration errors for different counting statistics. Up to energies of 60 keV systematic errors were measured to be le...

  16. Calibrating nacelle lidars

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, M.

    2013-01-15

    Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam inclination introduces extra uncertainties. A procedure for conducting such a calibration is presented and initial indications of the uncertainties given. A discussion of the merits and weaknesses of the two methods is given together with some proposals for the next important steps to be taken in this work. (Author)

  17. Breastfeeding vs. Formula Feeding

    Science.gov (United States)

    ... Parks EP, Shaikhkhalil A, Groleau V, Wendel D, Stallings VA. Feeding healthy infants, children, and adolescents. In: ... 2016:chap. Stettler N, Bhatia J, Parish A, Stallings VA. Feeding healthy infants, children, and adolescents. In: ...

  18. Ground calibrations of Nuclear Compton Telescope

    Science.gov (United States)

    Chiu, Jeng-Lun; Liu, Zhong-Kai; Bandstra, Mark S.; Bellm, Eric C.; Liang, Jau-Shian; Perez-Becker, Daniel; Zoglauer, Andreas; Boggs, Steven E.; Chang, Hsiang-Kuang; Chang, Yuan-Hann; Huang, Minghuey A.; Amman, Mark; Chiang, Shiuan-Juang; Hung, Wei-Che; Lin, Chih-Hsun; Luke, Paul N.; Run, Ray-Shine; Wunderer, Cornelia B.

    2010-07-01

    The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. The heart of NCT is an array of 12 cross-strip germanium detectors, designed to provide 3D positions for each photon interaction with full 3D position resolution to imaging, effectively reduces background, and enables the measurement of polarization. The keys to Compton imaging with NCT's detectors are determining the energy deposited in the detector at each strip and tracking the gamma-ray photon interaction within the detector. The 3D positions are provided by the orthogonal X and Y strips, and by determining the interaction depth using the charge collection time difference (CTD) between the anode and cathode. Calibrations of the energy as well as the 3D position of interactions have been completed, and extensive calibration campaigns for the whole system were also conducted using radioactive sources prior to our flights from Ft. Sumner, New Mexico, USA in Spring 2009, and from Alice Springs, Australia in Spring 2010. Here we will present the techniques and results of our ground calibrations so far, and then compare the calibration results of the effective area throughout NCT's field of view with Monte Carlo simulations using a detailed mass model.

  19. The LOFAR long baseline snapshot calibrator survey

    CERN Document Server

    Moldón, J; Wucknitz, O; Jackson, N; Drabent, A; Carozzi, T; Conway, J; Kapińska, A D; McKean, P; Morabito, L; Varenius, E; Zarka, P; Anderson, J; Asgekar, A; Avruch, I M; Bell, M E; Bentum, M J; Bernardi, G; Best, P; Bîrzan, L; Bregman, J; Breitling, F; Broderick, J W; Brüggen, M; Butcher, H R; Carbone, D; Ciardi, B; de Gasperin, F; de Geus, E; Duscha, S; Eislöffel, J; Engels, D; Falcke, H; Fallows, R A; Fender, R; Ferrari, C; Frieswijk, W; Garrett, M A; Grießmeier, J; Gunst, A W; Hamaker, J P; Hassall, T E; Heald, G; Hoeft, M; Juette, E; Karastergiou, A; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Kuper, G; Maat, P; Mann, G; Markoff, S; McFadden, R; McKay-Bukowski, D; Morganti, R; Munk, H; Norden, M J; Offringa, A R; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Reich, W; Röttgering, H; Rowlinson, A; Scaife, A M M; Schwarz, D; Sluman, J; Smirnov, O; Stappers, B W; Steinmetz, M; Tagger, M; Tang, Y; Tasse, C; Thoudam, S; Toribio, M C; Vermeulen, R; Vocks, C; van Weeren, R J; White, S; Wise, M W; Yatawatta, S; Zensus, A

    2014-01-01

    Aims. An efficient means of locating calibrator sources for International LOFAR is developed and used to determine the average density of usable calibrator sources on the sky for subarcsecond observations at 140 MHz. Methods. We used the multi-beaming capability of LOFAR to conduct a fast and computationally inexpensive survey with the full International LOFAR array. Sources were pre-selected on the basis of 325 MHz arcminute-scale flux density using existing catalogues. By observing 30 different sources in each of the 12 sets of pointings per hour, we were able to inspect 630 sources in two hours to determine if they possess a sufficiently bright compact component to be usable as LOFAR delay calibrators. Results. Over 40% of the observed sources are detected on multiple baselines between international stations and 86 are classified as satisfactory calibrators. We show that a flat low-frequency spectrum (from 74 to 325 MHz) is the best predictor of compactness at 140 MHz. We extrapolate from our sample to sho...

  20. Calibration of the Milagro Cosmic Ray Telescope

    CERN Document Server

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    1999-01-01

    The Milagro detector is an air shower array which uses the water Cherenkov technique and is capable of continuously monitoring the sky at energies near 1 TeV. The detector consists of 20000 metric tons of pure water instrumented with 723 photo-multiplier tubes (PMTs). The PMTs are arranged in a two-layer structure on a lattice of 3 m spacing covering 5000 $m^2$ area. The direction of the shower is determined from the relative timing of the PMT signals, necessitating a common time reference and amplitude slewing corrections to improve the time resolution. The calibration system to provide these consists of a pulsed laser driving 30 diffusing light sources deployed in the pond to allow cross-calibration of the PMTs. The system is capable of calibrating times and the pulse-heights from the PMTs using the time-over-threshold technique. The absolute energy scale is provided using single muons passing through the detector. The description of the calibration system of the Milagro detector and its prototype Milagrito...

  1. Calibration of the Nustar High-Energy Focusing X-Ray Telescope

    DEFF Research Database (Denmark)

    Madsen, Kristin K.; Harrison, Fiona A.; Markwardt, Craig B.;

    2015-01-01

    We present the calibration of the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray satellite. We used the Crab as the primary effective area calibrator and constructed a piece-wise linear spline function to modify the vignetting response. The achieved residuals for all off-axis angles and ene...

  2. The automatic calibration of Korean VLBI Network data

    CERN Document Server

    Hodgson, Jeffrey A; Zhao, Guang-Yao; Algaba, Juan-Carlos; Yun, Youngjoo; Jung, Taehyun; Byun, Do-Young

    2016-01-01

    The calibration of Very Long Baseline Interferometry (VLBI) data has long been a time consuming process. The Korean VLBI Network (KVN) is a simple array consisting of three identical antennas. Because four frequencies are observed simultaneously, phase solutions can be transferred from lower frequencies to higher frequencies in order to improve phase coherence and hence sensitivity at higher frequencies. Due to the homogeneous nature of the array, the KVN is also well suited for automatic calibration. In this paper we describe the automatic calibration of single-polarisation KVN data using the KVN Pipeline and comparing the results against VLBI data that has been manually reduced. We find that the pipelined data using phase transfer produces better results than a manually reduced dataset not using the phase transfer. Additionally we compared the pipeline results with a manually reduced phase-transferred dataset and found the results to be identical.

  3. The Automatic Calibration of Korean VLBI Network Data

    Science.gov (United States)

    Hodgson, Jeffrey A.; Lee, Sang-Sung; Zhao, Guang-Yao; Algaba, Juan-Carlos; Yun, Youngjoo; Jung, Taehyun; Byun, Do-Young

    2016-08-01

    The calibration of Very Long Baseline Interferometry (VLBI) data has long been a time consuming process. The Korean VLBI Network (KVN) is a simple array consisting of three identical antennas. Because four frequencies are observed simultaneously, phase solutions can be transferred from lower frequencies to higher frequencies in order to improve phase coherence and hence sensitivity at higher frequencies. Due to the homogeneous nature of the array, the KVN is also well suited for automatic calibration. In this paper we describe the automatic calibration of single-polarisation KVN data using the KVN Pipeline and comparing the results against VLBI data that has been manually reduced. We find that the pipelined data using phase transfer produces better results than a manually reduced dataset not using the phase transfer. Additionally we compared the pipeline results with a manually reduced phase-transferred dataset and found the results to be identical.

  4. Calibration Under Uncertainty.

    Energy Technology Data Exchange (ETDEWEB)

    Swiler, Laura Painton; Trucano, Timothy Guy

    2005-03-01

    This report is a white paper summarizing the literature and different approaches to the problem of calibrating computer model parameters in the face of model uncertainty. Model calibration is often formulated as finding the parameters that minimize the squared difference between the model-computed data (the predicted data) and the actual experimental data. This approach does not allow for explicit treatment of uncertainty or error in the model itself: the model is considered the %22true%22 deterministic representation of reality. While this approach does have utility, it is far from an accurate mathematical treatment of the true model calibration problem in which both the computed data and experimental data have error bars. This year, we examined methods to perform calibration accounting for the error in both the computer model and the data, as well as improving our understanding of its meaning for model predictability. We call this approach Calibration under Uncertainty (CUU). This talk presents our current thinking on CUU. We outline some current approaches in the literature, and discuss the Bayesian approach to CUU in detail.

  5. Polarimetric Palsar Calibration

    Science.gov (United States)

    Touzi, R.; Shimada, M.

    2008-11-01

    Polarimetric PALSAR system parameters are assessed using data sets collected over various calibration sites. The data collected over the Amazonian forest permits validating the zero Faraday rotation hypotheses near the equator. The analysis of the Amazonian forest data and the response of the corner reflectors deployed during the PALSAR acquisitions lead to the conclusion that the antenna is highly isolated (better than -35 dB). Theses results are confirmed using data collected over the Sweden and Ottawa calibration sites. The 5-m height trihedrals deployed in the Sweden calibration site by the Chalmers University of technology permits accurate measurement of antenna parameters, and detection of 2-3 degree Faraday rotation during day acquisition, whereas no Faraday rotation was noted during night acquisition. Small Faraday rotation angles (2-3 degree) have been measured using acquisitions over the DLR Oberpfaffenhofen and the Ottawa calibration sites. The presence of small but still significant Faraday rotation (2-3 degree) induces a CR return at the cross-polarization HV and VH that should not be interpreted as the actual antenna cross-talk. PALSAR antenna is highly isolated (better than -35 dB), and diagonal antenna distortion matrices (with zero cross-talk terms) can be used for accurate calibration of PALSAR polarimetric data.

  6. GTC Photometric Calibration

    Science.gov (United States)

    di Cesare, M. A.; Hammersley, P. L.; Rodriguez Espinosa, J. M.

    2006-06-01

    We are currently developing the calibration programme for GTC using techniques similar to the ones use for the space telescope calibration (Hammersley et al. 1998, A&AS, 128, 207; Cohen et al. 1999, AJ, 117, 1864). We are planning to produce a catalogue with calibration stars which are suitable for a 10-m telescope. These sources will be not variable, non binary and do not have infrared excesses if they are to be used in the infrared. The GTC science instruments require photometric calibration between 0.35 and 2.5 microns. The instruments are: OSIRIS (Optical System for Imaging low Resolution Integrated Spectroscopy), ELMER and EMIR (Espectrógrafo Multiobjeto Infrarrojo) and the Acquisition and Guiding boxes (Di Césare, Hammersley, & Rodriguez Espinosa 2005, RevMexAA Ser. Conf., 24, 231). The catalogue will consist of 30 star fields distributed in all of North Hemisphere. We will use fields containing sources over the range 12 to 22 magnitude, and spanning a wide range of spectral types (A to M) for the visible and near infrared. In the poster we will show the method used for selecting these fields and we will present the analysis of the data on the first calibration fields observed.

  7. Combining the switched-beam and beam-steering capabilities in a 2-D phased array antenna system

    Science.gov (United States)

    Tsai, Yi-Che; Chen, Yin-Bing; Hwang, Ruey-Bing

    2016-01-01

    This paper presents the development, fabrication, and measurement of a novel beam-forming system consisting of 16 subarray antennas, each containing four aperture-coupled patch antennas, and the application of this system in smart wireless communication systems. The beam patterns of each of the subarray antennas can be switched toward one of nine zones over a half space by adjusting the specific phase delay angles among the four antenna elements. Furthermore, when all subarrays are pointed at the same zone, slightly continuous beam steering in around 1° increments can be achieved by dynamically altering the progressive phase delay angle among the subarrays. Phase angle calibration was implemented by coupling each transmitter output and down converter into the in-phase/quadrature baseband to calculate the correction factor to the weight. In addition, to validate the proposed concepts and the fabricated 2-D phased array antenna system, this study measured the far-field radiation patterns of the aperture-coupled patch array integrated with feeding networks and a phase-calibration system to carefully verify its spatially switched-beam and beam-steering characteristics at a center frequency of 2.4 GHz which can cover the industrial, scientific, and medical band and some long-term evolution applications. In addition, measured results were compared with calculated results, and agreement between them was observed.

  8. Calibration artefacts in radio interferometry - III. Phase-only calibration and primary beam correction

    Science.gov (United States)

    Grobler, T. L.; Stewart, A. J.; Wijnholds, S. J.; Kenyon, J. S.; Smirnov, O. M.

    2016-09-01

    This is the third installment in a series of papers in which we investigate calibration artefacts. Calibration artefacts (also known as ghosts or spurious sources) are created when we calibrate with an incomplete model. In the first two papers of this series, we developed a mathematical framework which enabled us to study the ghosting mechanism itself. An interesting concomitant of the second paper was that ghosts appear in symmetrical pairs. This could possibly account for spurious symmetrization. Spurious symmetrization refers to the appearance of a spurious source (the antighost) symmetrically opposite an unmodelled source around a modelled source. The analysis in the first two papers indicates that the antighost is usually very faint, in particular, when a large number of antennas are used. This suggests that spurious symmetrization will mainly occur at an almost undetectable flux level. In this paper, we show that phase-only calibration produces an antighost that is N-times (where N denotes the number of antennas in the array) as bright as the one produced by phase and amplitude calibration and that this already bright ghost can be further amplified by the primary beam correction.

  9. Feed safety in the feed supply chain

    Directory of Open Access Journals (Sweden)

    Pinotti, L.

    2011-01-01

    Full Text Available A number of issues have weakened the public's confidence in the quality and wholesomeness of foods of animal origin. As a result farmers, nutritionists, industry and governments have been forced to pay serious attention to animal feedstuff production processes, thereby acknowledging that animal feed safety is an essential prerequisite for human food safety. Concerns about these issues have produced a number of important effects including the ban on the use of processed animal proteins, the ban on the addition of most antimicrobials to farm animals diets for growth‐promotion purposes, and the implementation of feed contaminant regulations in the EU. In this context it is essential to integrate knowledge on feed safety and feed supply. Consequently, purchase of new and more economic sources of energy and protein in animal diets, which is expected to conform to adequate quality, traceability, environmental sustainability and safety standards, is an emerging issue in livestock production system.

  10. Piezoresistive Foam Sensor Arrays for Marine Applications

    CERN Document Server

    Dusek, Jeff E; Lang, Jeffrey H

    2016-01-01

    Spatially-dense pressure measurements are needed on curved surfaces in marine environments to provide marine vehicles with the detailed, real-time measurements of the near-field flow necessary to improve performance through flow control. To address this challenge, a waterproof and conformal pressure sensor array comprising carbon black-doped-silicone closed-cell foam (CBPDMS foam) was developed for use in marine applications. The response of the CBPDMS foam sensor arrays was characterized using periodic hydrodynamic pressure stimuli from vertical plunging, from which a piecewise polynomial calibration was developed to describe the sensor response. Inspired by the distributed pressure and velocity sensing capabilities of the fish lateral line, the CBPDMS foam sensor arrays have significant advantages over existing commercial sensors for distributed flow reconstruction and control. Experimental results have shown the sensor arrays to have sensitivity on the order of 5 Pascal, dynamic range of 50-500 Pascal; are...

  11. TARGETLESS CAMERA CALIBRATION

    Directory of Open Access Journals (Sweden)

    L. Barazzetti

    2012-09-01

    Full Text Available In photogrammetry a camera is considered calibrated if its interior orientation parameters are known. These encompass the principal distance, the principal point position and some Additional Parameters used to model possible systematic errors. The current state of the art for automated camera calibration relies on the use of coded targets to accurately determine the image correspondences. This paper presents a new methodology for the efficient and rigorous photogrammetric calibration of digital cameras which does not require any longer the use of targets. A set of images depicting a scene with a good texture are sufficient for the extraction of natural corresponding image points. These are automatically matched with feature-based approaches and robust estimation techniques. The successive photogrammetric bundle adjustment retrieves the unknown camera parameters and their theoretical accuracies. Examples, considerations and comparisons with real data and different case studies are illustrated to show the potentialities of the proposed methodology.

  12. Performance evaluation and calibration issues of large format infrared hybrid active pixel sensors used for ground- and space-based astronomy

    International Nuclear Information System (INIS)

    Instruments for large 10-m class telescopes increasingly require high sensitivity large format focal planes. The high spatial resolution achieved with adaptive optics combined with multiple integral field units feeding high resolution spectrographs are driving the pixel performance and require large detector formats. In the infrared spectral range, the array formats have arrived at 2Kx2K pixels with both LPE and MBE grown HgCdTe on CdZnTe substrates. In the optical, fully depleted Si-PIN diodes of the same format are used. The light-sensitive diode arrays are hybridized to CMOS FET switched multiplexers such as the Hawaii-2RG array, which has recently been installed in one of the infrared instruments of the Very Large Telescope (VLT). Basic performance characteristics of the Hawaii-2RG arrays will be discussed such as the noise performance when a special technique of using reference pixels is employed. Larger focal planes are realized as mosaics of 2Kx2K arrays. In order to increase the format of single arrays to 4Kx4K and larger, the limited substrate sizes make it necessary to reduce the pixel size. However, with smaller pixels the coupling between pixels becomes a limiting factor for the detector point spread function. Fundamental calibration issues relevant to photon transfer techniques of modern CMOS active pixel sensors with special regard to the influence of interpixel coupling capacitances will be analyzed in detail. A novel technique will be presented to directly measure the point spread function generated by the capacitive coupling between adjacent pixels

  13. The MINOS calibration detector

    International Nuclear Information System (INIS)

    This paper describes the MINOS calibration detector (CalDet) and the procedure used to calibrate it. The CalDet, a scaled-down but functionally equivalent model of the MINOS Far and Near detectors, was exposed to test beams in the CERN PS East Area during 2001-2003 to establish the response of the MINOS calorimeters to hadrons, electrons and muons in the range 0.2-10GeV/c. The CalDet measurements are used to fix the energy scale and constrain Monte Carlo simulations of MINOS

  14. Individual dosimetry and calibration

    International Nuclear Information System (INIS)

    In 1995 both the Individual Dosimetry and Calibration Sections worked under the condition of a status quo and concentrated fully on the routine part of their work. Nevertheless, the machine for printing the bar code which will be glued onto the film holder and hence identify the people when entering into high radiation areas was put into operation and most of the holders were equipped with the new identification. As far as the Calibration Section is concerned the project of the new source control system that is realized by the Technical Support Section was somewhat accelerated

  15. HIBP calibration on WEGA stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Podoba, Yuriy; Otte, Matthias; Wagner, Friedrich [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Zhezhera, Alexander; Chmyga, Alexander; Kozachok, Alexander; Komarov, Alexander; Bondarenko, Ivan; Deshko, Galina; Khrebtov, Sergey; Krupnik, Ludmila [Kharkov Institute of Plasma Physics, Kharkov (Ukraine)

    2009-07-01

    The heavy ion beam probe (HIBP) is an established non-perturbing diagnostic for determining spatial distributions of plasma potential, density, temperature and poloidal magnetic field of magnetically confined plasmas. These quantities can be determined from the change in the ion beam parameters (charge, intensity and trajectory) passing through a plasma volume due to collisions with electrons and interactions with the confining magnetic field. The WEGA HIBP operates with a Na{sup +} with an energy of 39.5 keV and beam current 35 {mu}A. Conventionally the coordinate mapping of the HIBP is provided by ray tracing calculations of the ion beam in the magnetic field. However, it is very difficult to include all physical effects in the model, thus the result of the calculations may significantly differ from the real probing position. In order to improve the mapping precision an additional measurements of the beam position have been provided using a beam detector array inside the vacuum vessel. This allows to compare the measured and calculated ion beam position in order to find out the reasons for the coordinate mismatch and include adjustments in the calculation code. Results of this calibration are presented in this work.

  16. A novel array antenna for MSAT applications

    Science.gov (United States)

    Bodnar, Donald G.; Rainer, B. Keith; Rahmat-Samii, Yahya

    1989-01-01

    The issue of reducing the cost of phased array vehicle antennas through the use of a lens feeding arrangement instead of phase shifters at each element is addressed. In particular, the economic viability of a mobile satellite system (MSAT) is largely dependent on the efficient use of the allocated scarce spectrum and orbit as well as the satellite power. the type of vehicle antenna used will play a critical role in achieving this efficiency. A standard design approach for an electronically steered array uses phase shifters at each element to provide beam steering. A method for reducing the required number of phase shifters by using an R-KR lens feed network is outlined. The authors briefly discuss the phase shifter approach to beam steering, examine various lens feed techniques, and describe the R-KR lens approach. The lens feed network architecture is examined, a computer model for simulation of the array is presented, and the results of analysis of a suggested design for the MSAT application are given. In addition, satellite acquisition and tracking considerations are investigated.

  17. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    Science.gov (United States)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  18. The Calibration System of the HAWC Gamma-Ray Observatory

    CERN Document Server

    Solares, Hugo A Ayala; Hui, C Michelle; Lauer, Robert J; Ren, Zhixiang; Greus, Francisco Salesa; Zhou, Hao

    2015-01-01

    The HAWC collaboration has recently completed the construction of a gamma-ray observatory at an altitude of 4100 meters on the slope of the Sierra Negra volcano in the state of Puebla, Mexico. In order to achieve an optimal angular resolution, energy reconstruction, and cosmic-ray background suppression for the air showers observed by HAWC, it is crucial to obtain good timing and charge calibrations of the photosensors in the detector. The HAWC calibration is based on a laser system which is able to deliver short light pulses to all the tanks in the array. The light intensity can range over 7 orders of magnitude, broad enough to cover all the dynamic range of the PMT readout electronics. In this contribution we will present the HAWC calibration system, together with the methods used to calibrate the detector.

  19. White light spectral interferometry as a spectrometer calibration tool.

    Science.gov (United States)

    de la Fuente, Raúl

    2014-01-01

    For this paper, we used a white light interferometer in combination with spectral lamps to perform the wavelength calibration of a dispersive spectrometer. Illuminating the spectrometer with suitable spectral lamps gives the wavelength-pixel number relationship at discrete positions of the spectrometer detector array, and the wavelength-dependent phase difference at the output of the white light interferometer allows for a complete spectral calibration at any point on the detector (i.e., for every wavelength in the spectral range of the spectrometer). The details of this new calibration procedure are discussed, and two practical examples exhibiting the robustness of the method are presented. In addition, certain issues relating to minimizing the number of spectral lines used in the calibration procedure are examined.

  20. One step geometrical calibration method for optical coherence tomography

    International Nuclear Information System (INIS)

    We present a novel one-step calibration methodology for geometrical distortion correction for optical coherence tomography (OCT). A calibration standard especially designed for OCT is introduced, which consists of an array of inverse pyramidal structures. The use of multiple landmarks situated on four different height levels on the pyramids allow performing a 3D geometrical calibration. The calibration procedure itself is based on a parametric model of the OCT beam propagation. It is validated by experimental results and enables the reduction of systematic errors by more than one order of magnitude. In future, our results can improve OCT image reconstruction and interpretation for medical applications such as real time monitoring of surgery. (paper)

  1. Entropic calibration revisited

    Energy Technology Data Exchange (ETDEWEB)

    Brody, Dorje C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)]. E-mail: d.brody@imperial.ac.uk; Buckley, Ian R.C. [Centre for Quantitative Finance, Imperial College, London SW7 2AZ (United Kingdom); Constantinou, Irene C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Meister, Bernhard K. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

    2005-04-11

    The entropic calibration of the risk-neutral density function is effective in recovering the strike dependence of options, but encounters difficulties in determining the relevant greeks. By use of put-call reversal we apply the entropic method to the time reversed economy, which allows us to obtain the spot price dependence of options and the relevant greeks.

  2. Calibration of farmer dosemeters

    International Nuclear Information System (INIS)

    The Farmer Dosemeters of Atomic Energy Medical Centre (AEMC) Jamshoro were calibrated in the Secondary Standard Dosimetry Laboratory (SSDL) at PINSTECH, using the NPL Secondary Standard Therapy level X-ray exposure meter. The results are presented in this report. (authors)

  3. Calibration Of Oxygen Monitors

    Science.gov (United States)

    Zalenski, M. A.; Rowe, E. L.; Mcphee, J. R.

    1988-01-01

    Readings corrected for temperature, pressure, and humidity of air. Program for handheld computer developed to ensure accuracy of oxygen monitors in National Transonic Facility, where liquid nitrogen stored. Calibration values, determined daily, based on entries of data on barometric pressure, temperature, and relative humidity. Output provided directly in millivolts.

  4. Commodity-Free Calibration

    Science.gov (United States)

    2008-01-01

    Commodity-free calibration is a reaction rate calibration technique that does not require the addition of any commodities. This technique is a specific form of the reaction rate technique, where all of the necessary reactants, other than the sample being analyzed, are either inherent in the analyzing system or specifically added or provided to the system for a reason other than calibration. After introduction, the component of interest is exposed to other reactants or flow paths already present in the system. The instrument detector records one of the following to determine the rate of reaction: the increase in the response of the reaction product, a decrease in the signal of the analyte response, or a decrease in the signal from the inherent reactant. With this data, the initial concentration of the analyte is calculated. This type of system can analyze and calibrate simultaneously, reduce the risk of false positives and exposure to toxic vapors, and improve accuracy. Moreover, having an excess of the reactant already present in the system eliminates the need to add commodities, which further reduces cost, logistic problems, and potential contamination. Also, the calculations involved can be simplified by comparison to those of the reaction rate technique. We conducted tests with hypergols as an initial investigation into the feasiblility of the technique.

  5. Measurement System & Calibration report

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    This Measurement System & Calibration report is describing DTU’s measurement system installed at a specific wind turbine. A major part of the sensors has been installed by others (see [1]) the rest of the sensors have been installed by DTU. The results of the measurements, described in this report...

  6. Calibration with Absolute Shrinkage

    DEFF Research Database (Denmark)

    Øjelund, Henrik; Madsen, Henrik; Thyregod, Poul

    2001-01-01

    In this paper, penalized regression using the L-1 norm on the estimated parameters is proposed for chemometric je calibration. The algorithm is of the lasso type, introduced by Tibshirani in 1996 as a linear regression method with bound on the absolute length of the parameters, but a modification...

  7. NVLAP calibration laboratory program

    Energy Technology Data Exchange (ETDEWEB)

    Cigler, J.L.

    1993-12-31

    This paper presents an overview of the progress up to April 1993 in the development of the Calibration Laboratories Accreditation Program within the framework of the National Voluntary Laboratory Accreditation Program (NVLAP) at the National Institute of Standards and Technology (NIST).

  8. Array antennas design in dependence of element-phasing

    Science.gov (United States)

    Zichner, R.; Chandra, M.

    2009-05-01

    Array antennas are used in science as well as for commercial and military purposes. The used element antennas act in accordance to their desired uses, for example radars or stationer GPS satellites. Typical components are for example slotted waveguides, patches, yagi-antennas and helix-antennas. All these elements do stand out with their own characteristics based on their special applications. If these elements are formed into an array configuration, the effectiveness can be improved immensely. There is a relation between the array functions and the physical array properties like the element alignment (linear, planar, circular), distances between the elements and so on. Among the physical properties there are other attributes like phase or amplitude coefficients, which are of great significance. The aim of this study was to provide an insight into the problem of array design, as far as the antenna element phase is concerned. Along with this, array radiation characteristics effects are presented. With the help of the extracted cognitions beam forming behaviour can be shown and the array phase behaviour can be analysed. One of the main applications is to simulate the array characteristics, like the radiation characteristic or the gain, for displacements of the array feeding point. A software solution that simulates the phase shift of a given array pattern is sought to adjust the feeding point.

  9. Array antennas design in dependence of element-phasing

    Directory of Open Access Journals (Sweden)

    R. Zichner

    2009-05-01

    Full Text Available Array antennas are used in science as well as for commercial and military purposes. The used element antennas act in accordance to their desired uses, for example radars or stationer GPS satellites. Typical components are for example slotted waveguides, patches, yagi-antennas and helix-antennas. All these elements do stand out with their own characteristics based on their special applications. If these elements are formed into an array configuration, the effectiveness can be improved immensely. There is a relation between the array functions and the physical array properties like the element alignment (linear, planar, circular, distances between the elements and so on. Among the physical properties there are other attributes like phase or amplitude coefficients, which are of great significance. The aim of this study was to provide an insight into the problem of array design, as far as the antenna element phase is concerned. Along with this, array radiation characteristics effects are presented. With the help of the extracted cognitions beam forming behaviour can be shown and the array phase behaviour can be analysed. One of the main applications is to simulate the array characteristics, like the radiation characteristic or the gain, for displacements of the array feeding point. A software solution that simulates the phase shift of a given array pattern is sought to adjust the feeding point.

  10. Pleiades Absolute Calibration : Inflight Calibration Sites and Methodology

    Science.gov (United States)

    Lachérade, S.; Fourest, S.; Gamet, P.; Lebègue, L.

    2012-07-01

    In-flight calibration of space sensors once in orbit is a decisive step to be able to fulfil the mission objectives. This article presents the methods of the in-flight absolute calibration processed during the commissioning phase. Four In-flight calibration methods are used: absolute calibration, cross-calibration with reference sensors such as PARASOL or MERIS, multi-temporal monitoring and inter-bands calibration. These algorithms are based on acquisitions over natural targets such as African deserts, Antarctic sites, La Crau (Automatic calibration station) and Oceans (Calibration over molecular scattering) or also new extra-terrestrial sites such as the Moon and selected stars. After an overview of the instrument and a description of the calibration sites, it is pointed out how each method is able to address one or several aspects of the calibration. We focus on how these methods complete each other in their operational use, and how they help building a coherent set of information that addresses all aspects of in-orbit calibration. Finally, we present the perspectives that the high level of agility of PLEIADES offers for the improvement of its calibration and a better characterization of the calibration sites.

  11. Mercury CEM Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  12. Thin conformal antenna array for microwave power conversions

    Science.gov (United States)

    Dickinson, R. M. (Inventor)

    1978-01-01

    A structure of a circularly polarized, thin conformal, antenna array which may be mounted integrally with the skin of an aircraft employs microstrip elliptical elements and interconnecting feed lines spaced from a circuit ground plane by a thin dielectric layer. The feed lines are impedance matched to the elliptical antenna elements by selecting a proper feedpoint inside the periphery of the elliptical antenna elements. Diodes connected between the feed lines and the ground plane rectify the microwave power, and microstrip filters (low pass) connected in series with the feed lines provide dc current to a microstrip bus. Low impedance matching strips are included between the elliptical elements and the rectifying and filtering elements.

  13. Is gastric sham feeding really sham feeding?

    Science.gov (United States)

    Sclafani, A; Nissenbaum, J W

    1985-03-01

    Rats were fitted with gastric cannulas, food deprived, and allowed to drink a sugar solution that drained out of the opened cannula; i.e., the rats sham-fed. Although this procedure is thought to prevent absorption of ingested food, it was found that the sham feeding of a 32% glucose or sucrose solution significantly elevated blood glucose levels. The addition of acarbose, a drug that inhibits the digestion of sucrose, to the 32% sucrose solution blocked the blood glucose rise, as did closing the pylorus with an inflatable pyloric cuff. Neither the drug nor the cuff, however, reduced the amount of sucrose solution consumed. These findings indicate that gastric sham feeding does not necessarily prevent the digestion and absorption of food, although absorption is not essential for the appearance of a vigorous sham-feeding response. Nevertheless the possibility that neural or hormonal feedback from the stomach contributes to the sham-feeding response cannot be excluded, and until this issue is resolved the results of gastric sham-feeding studies should be interpreted with caution.

  14. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Schmidt Paulsen, Uwe; Mortensen, Niels Gylling; Hansen, Jens Carsten;

    2007-01-01

    A field calibration method and results are described along with the experience gained with the method. The cup anemometers to be calibrated are mounted in a row on a 10-m high rig and calibrated in the free wind against a reference cup anemometer. The method has been reported [1] to improve the...... statistical bias on the data relative to calibrations carried out in a wind tunnel. The methodology is sufficiently accurate for calibration of cup anemometers used for wind resource assessments and provides a simple, reliable and cost-effective solution to cup anemometer calibration, especially suited for...

  15. VLBI2010 Feed Comparison

    Science.gov (United States)

    Petrachenko, Bill

    2013-01-01

    VLBI2010 requires a feed that simultaneously has high efficiency over the full 2.2-14 GHz frequency range. The simultaneity requirement implies that the feed must operate at high efficiency over the full frequency range without the need to adjust its focal position to account for frequency dependent phase centre variations. Two feeds meet this specification: The Eleven Feed developed at Chalmers University. (For more information, contact Miroslav Pantaleev, miroslav.pantaleev@chalmers.se. The Eleven Feed, integrated with LNA's in a cryogenic receiver, is available as a product from Omnisys Instruments, info@omnisys.se). The Quadruple Ridged Flared Horn (QRFH) developed at the California Institute of Technology. (For more information please contact Ahmed Akgiray, aakgiray@ieee.org or Sander Weinreb, sweinreb@caltech.edu) Although not VLBI2010 compliant, two triband S/X/Ka feeds are also being developed for the commissioning of VLBI2010 antennas, for S/X observations during the VLBI2010 transition period, and to support X/Ka CRF observations. The two feeds are: The Twin Telescopes Wettzell (TTW) triband feed developed by Mirad Microwave. (For more information please contact Gerhard Kronschnabl, Gerhard.Kronschnabl@bkg.bund.de) The RAEGE (Spain) triband feed developed at Yebes Observatory. (For more information please contact Jose Antonio Lopez Perez, ja.lopezperez@oan.es)

  16. High-Directivity Antenna Array Based on Artificial Electromagnetic Metamaterials with Low Refractive Index

    Directory of Open Access Journals (Sweden)

    Zhigang Xiao

    2015-01-01

    Full Text Available Planar metamaterials (MTMs with low refractive index are proposed as a cover in a high-gain patch antenna array configuration. This MTMs array antenna has the following features: the number of array elements significantly decreases compared with the conventional array; the elements spacing is larger than a wave length by far; the feeding network is simpler. MTMs are made of two layers of periodic square metallic grids and placed above the feeding array. With the same aperture size, the directivity of MTMs-cover antenna array is higher than the conventional antenna array. The simulation results show that an array of 2 × 2 patch elements integrated with MTMs yields about 26 dB of directivity which is higher than that of conventional 8 × 8 patch array. Furthermore, on the condition of the same aperture size, an array patch with 4 × 4 elements integrated with the MTMs-cover has an equivalent gain compared with the conventional patch array with 16 × 16 array elements. Obviously, the former has a simpler feeding network and higher aperture efficiency. The experimental work has verified that the 2 × 2 array case and the measured results have good agreement with the simulation.

  17. Series-Fed Microstrip Array Antenna with Circular Polarization

    OpenAIRE

    Tuan-Yung Han

    2012-01-01

    This study proposes a novel 2 × 2 array antenna design with broadband and circularly-polarized (CP) operation. The proposed design uses a simple series-fed network to increase the CP bandwidth without requiring one-by-one adjustment of each array element or a complex feed network. Selecting the appropriate spacing between each array element allows the proposed array antenna to generate CP radiation with a low axial ratio. Experimental results based on a prototype show that this 2 × 2 microstr...

  18. Calibrating the Prominence Magnetometer (ProMag)

    Science.gov (United States)

    Fox, Lewis; Casini, R.

    2013-07-01

    The Prominence Magnetometer (ProMag) is a dual-channel, dual-beam, slit-scanning, full Stokes spectro-polarimeter designed by the High Altitude Observatory at the National Center for Atmospheric Research (HAO/NCAR) for the study of the magnetism of solar prominences and filaments. It was deployed in August 2009 at the 40 cm coronagraph of the Evans Solar Facility (ESF) of the National Solar Observatory on Sacramento Peak (NSO/SP). In its standard mode of operation it acquires spectro-polarimetric maps of solar targets simultaneously in the two chromospheric lines of He I at 587.6 nm and 1083.0 nm. Since August 2011 ProMag has operated in “patrol mode” with a dedicated observer. We aim to routinely measure the vector magnetic field in prominences. The electro-optic modulator and polarization analyzer are integrated into a single mechanical unit located at the coude feed of the telescope. This location was necessary for proper co-alignment of the dual beams, but complicates the precise polarimeter calibration necessary to achieve the sensitivity required for prominence measurements (calibration method for ProMag, using a polarizer and retarder at coronagraph prime focus. Calibrations are recorded before and after observations. We discuss the success of this method and its limitations.

  19. Polarimetric calibration of large mirrors

    CERN Document Server

    Ariste, A Lopez

    2015-01-01

    Aims: To propose a method for the polarimetric calibration of large astronomical mirrors that does not require use of special optical devices nor knowledge of the exact polarization properties of the calibration target. Methods: We study the symmetries of the Mueller matrix of mirrors to exploit them for polarimetric calibration under the assumptions that only the orientation of the linear polarization plane of the calibration target is known with certainty. Results: A method is proposed to calibrate the polarization effects of single astronomical mirrors by the observation of calibration targets with known orientation of the linear polarization. We study the uncertainties of the method and the signal-to-noise ratios required for an acceptable calibration. We list astronomical targets ready for the method. We finally extend the method to the calibration of two or more mirrors, in particular to the case when they share the same incidence plane.

  20. The Calibration Reference Data System

    Science.gov (United States)

    Greenfield, P.; Miller, T.

    2016-07-01

    We describe a software architecture and implementation for using rules to determine which calibration files are appropriate for calibrating a given observation. This new system, the Calibration Reference Data System (CRDS), replaces what had been previously used for the Hubble Space Telescope (HST) calibration pipelines, the Calibration Database System (CDBS). CRDS will be used for the James Webb Space Telescope (JWST) calibration pipelines, and is currently being used for HST calibration pipelines. CRDS can be easily generalized for use in similar applications that need a rules-based system for selecting the appropriate item for a given dataset; we give some examples of such generalizations that will likely be used for JWST. The core functionality of the Calibration Reference Data System is available under an Open Source license. CRDS is briefly contrasted with a sampling of other similar systems used at other observatories.

  1. Swift/BAT Calibration and Spectral Response

    Science.gov (United States)

    Parsons, A.

    2004-01-01

    The Burst Alert Telescope (BAT) aboard NASA#s Swift Gamma-Ray Burst Explorer is a large coded aperture gamma-ray telescope consisting of a 2.4 m (8#) x 1.2 m (4#) coded aperture mask supported 1 meter above a 5200 square cm area detector plane containing 32,768 individual 4 mm x 4 mm x 2 mm CZT detectors. The BAT is now completely assembled and integrated with the Swift spacecraft in anticipation of an October 2004 launch. Extensive ground calibration measurements using a variety of radioactive sources have resulted in a moderately high fidelity model for the BAT spectral and photometric response. This paper describes these ground calibration measurements as well as related computer simulations used to study the efficiency and individual detector properties of the BAT detector array. The creation of a single spectral response model representative of the fully integrated BAT posed an interesting challenge and is at the heart of the public analysis tool #batdrmgen# which computes a response matrix for any given sky position within the BAT FOV. This paper will describe the batdrmgen response generator tool and conclude with a description of the on-orbit calibration plans as well as plans for the future improvements needed to produce the more detailed spectral response model that is required for the construction of an all-sky hard x-ray survey.

  2. Lidar calibration experiments

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.; Streicher, J.;

    1997-01-01

    A series of atmospheric aerosol diffusion experiments combined with lidar detection was conducted to evaluate and calibrate an existing retrieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost) identical mini-lidar systems for aerosol cloud...... detection to test the reproducibility and uncertainty of lidars. Lidar data were obtained from both single-ended and double-ended Lidar configurations. A backstop was introduced in one of the experiments and a new method was developed where information obtained from the backstop can be used in the inversion...... algorithm. Independent in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF6, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including measurements from both sides of a plume...

  3. Optical tweezers absolute calibration

    CERN Document Server

    Dutra, R S; Neto, P A Maia; Nussenzveig, H M

    2014-01-01

    Optical tweezers are highly versatile laser traps for neutral microparticles, with fundamental applications in physics and in single molecule cell biology. Force measurements are performed by converting the stiffness response to displacement of trapped transparent microspheres, employed as force transducers. Usually, calibration is indirect, by comparison with fluid drag forces. This can lead to discrepancies by sizable factors. Progress achieved in a program aiming at absolute calibration, conducted over the past fifteen years, is briefly reviewed. Here we overcome its last major obstacle, a theoretical overestimation of the peak stiffness, within the most employed range for applications, and we perform experimental validation. The discrepancy is traced to the effect of primary aberrations of the optical system, which are now included in the theory. All required experimental parameters are readily accessible. Astigmatism, the dominant effect, is measured by analyzing reflected images of the focused laser spo...

  4. Proportional microvolume capacitive liquid level sensor array.

    Science.gov (United States)

    Seliskar, D; Waterbury, R; Kearney, R

    2005-01-01

    A sensor array has been developed for use with laboratory automation to permit closed-loop control of liquid levels in a multiwell microplate geometry. We extended a simple electrical model for non-contact capacitance-based fluid sensors to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer, employing a liquid-specific calibration, can be used to obtain an output signal that varies linearly with the liquid level. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. A prototype 3×3 sensor array was built and tested using NaCl and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Calibrated output signals were linear with liquid volume for all tested solutions (R2>0.92). Measurement error averaged 1.3 % (2.0 μl) with a standard deviation of 6.0% (9.0 μl). These results demonstrate the feasibility of developing a microvolume sensor array in essentially any M×N microplate geometry. PMID:17281955

  5. Astrid-2 SSC ASUMagnetic Calibration

    DEFF Research Database (Denmark)

    Primdahl, Fritz

    1997-01-01

    Report of the inter calibration between the starcamera and the fluxgate magnetometer onboard the ASTRID-2 satellite. This calibration was performed in the night between the 15. and 16. May 1997 at the Lovö magnetic observatory.......Report of the inter calibration between the starcamera and the fluxgate magnetometer onboard the ASTRID-2 satellite. This calibration was performed in the night between the 15. and 16. May 1997 at the Lovö magnetic observatory....

  6. Program Calibrates Strain Gauges

    Science.gov (United States)

    Okazaki, Gary D.

    1991-01-01

    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

  7. Mesoscale hybrid calibration artifact

    Science.gov (United States)

    Tran, Hy D.; Claudet, Andre A.; Oliver, Andrew D.

    2010-09-07

    A mesoscale calibration artifact, also called a hybrid artifact, suitable for hybrid dimensional measurement and the method for make the artifact. The hybrid artifact has structural characteristics that make it suitable for dimensional measurement in both vision-based systems and touch-probe-based systems. The hybrid artifact employs the intersection of bulk-micromachined planes to fabricate edges that are sharp to the nanometer level and intersecting planes with crystal-lattice-defined angles.

  8. Dosimetry and Calibration Section

    International Nuclear Information System (INIS)

    The two tasks of the Dosimetry and Calibration Section at CERN are the Individual Dosimetry Service which assures the personal monitoring of about 5000 persons potentially exposed to ionizing radiation at CERN, and the Calibration Laboratory which verifies all the instruments and monitors. This equipment is used by the sections of the RP Group for assuring radiation protection around CERN's accelerators, and by the Environmental Section of TISTE. In addition, nearly 250 electronic and 300 quartz fibre dosimeters, employed in operational dosimetry, are calibrated at least once a year. The Individual Dosimetry Service uses an extended database (INDOS) which contains information about all the individual doses ever received at CERN. For most of 1997 it was operated without the support of a database administrator as the technician who had assured this work retired. The Software Support Section of TIS-TE took over the technical responsibility of the database, but in view of the many other tasks of this Section and the lack of personnel, only a few interventions for solving immediate problems were possible

  9. Calibration of Radio Interferometers Using a Sparse DoA Estimation Framework

    CERN Document Server

    Brossard, Martin; Pesavento, Marius; Boyer, Rémy; Larzabal, Pascal

    2016-01-01

    The calibration of modern radio interferometers is a significant challenge, specifically at low frequencies. In this perspective, we propose a novel iterative calibration algorithm, which employs the popular sparse representation framework, in the regime where the propagation conditions bend dissimilarly the directions of the sources. More precisely, our algorithm is designed to estimate the apparent directions of the calibration sources, their powers, the directional and undirectional complex gains of the array elements and their noise powers, with a reasonable computational complexity. Numerical simulations reveal that the proposed scheme is statistically efficient at low SNR and even with additional non-calibration sources at unknown directions.

  10. Calibration of Underwater Sound Transducers

    Directory of Open Access Journals (Sweden)

    H.R.S. Sastry

    1983-07-01

    Full Text Available The techniques of calibration of underwater sound transducers for farfield, near-field and closed environment conditions are reviewed in this paper .The design of acoustic calibration tank is mentioned. The facilities available at Naval Physical & Oceanographic Laboratory, Cochin for calibration of transducers are also listed.

  11. Feed up, Feedback, and Feed Forward

    Science.gov (United States)

    Fisher, Douglas; Frey, Nancy

    2011-01-01

    "Feeding up" establishes a substantive line of inquiry that compels learners to engage in investigation and inquire. It also forms the basis for the assessments that follow. Once students understand the purpose and begin to work, they receive "feedback" that is timely and scaffolds their understanding. Based on their responses, the teacher gains a…

  12. Selection of Feed Intake or Feed Efficiency

    DEFF Research Database (Denmark)

    Veerkamp, Roel F; Pryce, Jennie E; Spurlock, Diane;

    2013-01-01

    The widespread use of genomic information in dairy cattle breeding programs has opend up the possibility to select for novel traits, especially for traits that are traditionally difficult to record in a progeny testing scheme. Feed intake and efficiency is such a difficult to measure trait. In Fe...

  13. Danger of zooplankton feeding

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Jiang, H.; Colin, S.P.

    2010-01-01

    Zooplankton feed in any of three ways: they generate a feeding current while hovering, cruise through the water or are ambush feeders. Each mode generates different hydrodynamic disturbances and hence exposes the grazers differently to mechanosensory predators. Ambush feeders sink slowly and ther...

  14. Acoustic Array Development for Wind Turbine Noise Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Buck, S.; Roadman, J.; Moriarty, P.; Palo, S.

    2013-11-01

    This report discusses the design and use of a multi-arm, logarithmic spiral acoustic array by the National Renewable Energy Laboratory (NREL) for measurement and characterization of wind turbine-generated noise. The array was developed in collaboration with a team from the University of Colorado Boulder. This design process is a continuation of the elliptical array design work done by Simley. A description of the array system design process is presented, including array shape design, mechanical design, design of electronics and the data acquisition system, and development of post-processing software. System testing and calibration methods are detailed. Results from the initial data acquisition campaign are offered and discussed. Issues faced during this initial deployment of the array are presented and potential remedies discussed.

  15. Transition feeding of sows

    DEFF Research Database (Denmark)

    Theil, Peter Kappel

    2015-01-01

    becomes catabolic due to the high priority of milk production and to current feeding practices. Indeed, feed is changed from a gestation to a lactation diet for most sows and the feed supply typically goes from a restricted supply to an ad libitum allowance. In addition, transition sows are often exposed...... the first few days of lactation, and milk yield increases throughout the transition period and becomes the most important determinant of nutrient requirements. Thus, nutrient requirements of transition sows are affected by many intrinsic factors and these requirements change rapidly, yet, sow feeding...... practices do not acknowledge these changes. Development of new feeding strategies specifically adapted for the transition sow is likely of importance to match the rapid changes in nutrient requirements....

  16. The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies

    CERN Document Server

    Tingay, S J; Bowman, J D; Emrich, D; Ord, S M; Mitchell, D A; Morales, M F; Booler, T; Crosse, B; Pallot, D; Wicenec, A; Arcus, W; Barnes, D; Bernardi, G; Briggs, F; Burns, S; Bunton, J D; Cappallo, R J; Colegate, T; Corey, B E; Deshpande, A; deSouza, L; Gaensler, B M; Greenhill, L J; Hall, J; Hazelton, B J; Herne, D; Hewitt, J N; Johnston-Hollitt, M; Kaplan, D L; Kasper, J C; Kincaid, B B; Koenig, R; Kratzenberg, E; Lonsdale, C J; Lynch, M J; McKinley, B; McWhirter, S R; Morgan, E; Oberoi, D; Pathikulangara, J; Prabu, T; Remillard, R A; Rogers, A E E; Roshi, A; Salah, J E; Sault, R J; Udaya-Shankar, N; Schlagenhaufer, F; Srivani, K S; Stevens, J; Subrahmanyan, R; Tremblay, S; Wayth, R B; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C L; Wyithe, J S B

    2012-01-01

    The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80-300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3 km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.

  17. Monte Carlo simulation of the standardization of {sup 22}Na using scintillation detector arrays

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Y., E-mail: yss.sato@aist.go.j [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Quantum Radiation Division, Radioactivity and Neutron Section, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Murayama, H. [National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage, Chiba 263-8555 (Japan); Yamada, T. [Japan Radioisotope Association, 2-28-45, Hon-komagome, Bunkyo, Tokyo 113-8941 (Japan); National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Quantum Radiation Division, Radioactivity and Neutron Section, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Tohoku University, 6-6, Aoba, Aramaki, Aoba, Sendai 980-8579 (Japan); Hasegawa, T. [Kitasato University, 1-15-1, Kitasato, Sagamihara, Kanagawa 228-8555 (Japan); Oda, K. [Tokyo Metropolitan Institute of Gerontology, 1-1 Nakacho, Itabashi-ku, Tokyo 173-0022 (Japan); Unno, Y.; Yunoki, A. [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Quantum Radiation Division, Radioactivity and Neutron Section, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2010-07-15

    In order to calibrate PET devices by a sealed point source, we contrived an absolute activity measurement method for the sealed point source using scintillation detector arrays. This new method was verified by EGS5 Monte Carlo simulation.

  18. Calibration effects on orbit determination

    Science.gov (United States)

    Madrid, G. A.; Winn, F. B.; Zielenbach, J. W.; Yip, K. B.

    1974-01-01

    The effects of charged particle and tropospheric calibrations on the orbit determination (OD) process are analyzed. The calibration process consisted of correcting the Doppler observables for the media effects. Calibrated and uncalibrated Doppler data sets were used to obtain OD results for past missions as well as Mariner Mars 1971. Comparisons of these Doppler reductions show the significance of the calibrations. For the MM'71 mission, the media calibrations proved themselves effective in diminishing the overall B-plane error and reducing the Doppler residual signatures.

  19. Photometric Calibration of Consumer Video Cameras

    Science.gov (United States)

    Suggs, Robert; Swift, Wesley, Jr.

    2007-01-01

    Equipment and techniques have been developed to implement a method of photometric calibration of consumer video cameras for imaging of objects that are sufficiently narrow or sufficiently distant to be optically equivalent to point or line sources. Heretofore, it has been difficult to calibrate consumer video cameras, especially in cases of image saturation, because they exhibit nonlinear responses with dynamic ranges much smaller than those of scientific-grade video cameras. The present method not only takes this difficulty in stride but also makes it possible to extend effective dynamic ranges to several powers of ten beyond saturation levels. The method will likely be primarily useful in astronomical photometry. There are also potential commercial applications in medical and industrial imaging of point or line sources in the presence of saturation.This development was prompted by the need to measure brightnesses of debris in amateur video images of the breakup of the Space Shuttle Columbia. The purpose of these measurements is to use the brightness values to estimate relative masses of debris objects. In most of the images, the brightness of the main body of Columbia was found to exceed the dynamic ranges of the cameras. A similar problem arose a few years ago in the analysis of video images of Leonid meteors. The present method is a refined version of the calibration method developed to solve the Leonid calibration problem. In this method, one performs an endto- end calibration of the entire imaging system, including not only the imaging optics and imaging photodetector array but also analog tape recording and playback equipment (if used) and any frame grabber or other analog-to-digital converter (if used). To automatically incorporate the effects of nonlinearity and any other distortions into the calibration, the calibration images are processed in precisely the same manner as are the images of meteors, space-shuttle debris, or other objects that one seeks to

  20. Operational Land Imager relative radiometric calibration

    Science.gov (United States)

    Barsi, Julia A.; Markham, Brian L.

    2015-09-01

    The Operational Land Imager (OLI), on board the Landsat-8 satellite, is a pushbroom sensor with nearly 7000 detectors per band, divided between 14 separate modules. While rigorously characterized prior to launch, the shear number of individual detectors presents a challenge to maintaining the on-orbit relative calibration, such that stripes, bands and other artifacts are minimized in the final image products. On-orbit relative calibration of the OLI is primarily monitored and corrected by observing an on-board primary solar diffuser panel. The panel is the most uniform target available to the OLI, though as observed but the OLI, it has a slope across the field of view due to view angle effects. Just after launch, parameters were derived using the solar diffuser data, to correct for the angular effects across the 14 modules. The residual discontinuities between arrays and the detector-to-detector uniformity continue to be monitored on a weekly basis. The observed variations in the responses to the diffuser panel since launch are thought to be due to real instrument changes. Since launch, the Coastal/Aerosol (CA) and Blue bands have shown the most variation in relative calibration of the VNIR bands, with as much as 0.14% change (3-sigma) between consecutive relative gain estimates. The other VNIR bands (Green, Red and NIR) initially had detectors showing a slow drift of about 0.2% per year, though this stopped after an instrument power cycle about seven months after launch. The SWIR bands also exhibit variability between collects (0.11% 3-sigma) but the larger changes have been where individual detectors' responses change suddenly by as much as 1.5%. The mechanisms behind these changes are not well understood but in order to minimize impact to the users, the OLI relative calibration is updated on a quarterly basis in order to capture changes over time.

  1. HAWC Timing Calibration

    OpenAIRE

    Huentemeyer, Petra; Matthews, John A. J.; Dingus, Brenda

    2009-01-01

    The High-Altitude Water Cherenkov (HAWC) Experiment is a second-generation highsensitivity gamma-ray and cosmic-ray detector that builds on the experience and technology of the Milagro observatory. Like Milagro, HAWC utilizes the water Cherenkov technique to measure extensive air showers. Instead of a pond filled with water (as in Milagro) an array of closely packed water tanks is used. The event direction will be reconstructed using the times when the PMTs in each tank are triggered. Therefo...

  2. A variable acceleration calibration system

    Science.gov (United States)

    Johnson, Thomas H.

    2011-12-01

    A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of uncertainty analysis. Three types of uncertainty are indentified for the systems and are attributed to prediction error, calibration error and pure error. Angular velocity uncertainty is shown to be the largest indentified source of prediction error. The calibration uncertainties using a production variable acceleration based system are shown to be potentially equivalent to current methods. The production quality system can be realized using lighter materials and a more precise instrumentation. Further research is needed to account for balance deflection, forcing effects due to vibration, and large tare loads. A gyroscope measurement technique is shown to be capable of resolving the balance deflection angle calculation. Long term research objectives include a demonstration of a six degree of freedom calibration, and a large capacity balance calibration.

  3. Clearing obstructed feeding tubes.

    Science.gov (United States)

    Marcuard, S P; Stegall, K L; Trogdon, S

    1989-01-01

    This is a report of an in vitro study evaluating the ability of six solutions to dissolve clotted enteral feeding, which can cause feeding tube occlusion. The following clotted enteral feeding products were tested: Ensure Plus, Ensure Plus with added protein (Promod 20 g/liter), Osmolite, Enrich, and Pulmocare. Clot dissolution was then tested by adding Adolf's Meat Tenderizer, Viokase, Sprite, Pepsi, Coke, or Mountain Dew. Distilled water served as control. Dissolution score for each mixture was assessed blindly. Best dissolution was observed with Viokase in pH 7.9 solution (p less than 0.01). Similar results were obtained when feeding tube patency was restored in eight in vitro occluded feeding tubes (Dobbhoff, French size 8) by using first Pepsi (two/eight successful) and then Viokase in pH 7.9 (six/six successful). We also report our experience in the first 10 patients with occluded feeding tubes using this Viokase solution injected through a Drum catheter into the feeding tube. In seven patients, this method proved to be successful, and the reasons for failure in three patients include a knotted tube, impacted tablet powder, and a formula clot fo 24 hr duration and 45 cm in length. PMID:2494372

  4. ACA phase calibration scheme with the ALMA water vapor radiometers

    Science.gov (United States)

    Asaki, Yoshiharu; Matsushita, Satoki; Morita, Koh-Ichiro; Nikolic, Bojan

    2012-09-01

    In Atacama Large Millimeter/submillimeter Array (ALMA) commissioning and science verification we have conducted a series of experiments of a novel phase calibration scheme for Atacama Compact Array (ACA). In this scheme water vapor radiometers (WVRs) devoted to measurements of tropospheric water vapor content are attached to ACA’s four total-power array (TP Array) antennas surrounding the 7 m dish interferometer array (7 m Array). The excess path length (EPL) due to the water vapor variations aloft is fitted to a simple two-dimensional slope using WVR measurements. Interferometric phase fluctuations for each baseline of the 7 m Array are obtained from differences of EPL inferred from the two-dimensional slope and subtracted from the interferometric phases. In the experiments we used nine ALMA 12-m antennas. Eight of them were closely located in a 70-m square region, forming a compact array like ACA. We supposed the most four outsiders to be the TP Array while the inner 4 antennas were supposed to be the 7 m Array, so that this phase correction scheme (planar-fit) was tested and compared with the WVR phase correction. We estimated residual root-mean-square (RMS) phases for 17- to 41-m baselines after the planar-fit phase correction, and found that this scheme reduces the RMS phase to a 70 - 90 % level. The planar-fit phase correction was proved to be promising for ACA, and how high or low PWV this scheme effectively works in ACA is an important item to be clarified.

  5. SAR antenna calibration techniques

    Science.gov (United States)

    Carver, K. R.; Newell, A. C.

    1978-01-01

    Calibration of SAR antennas requires a measurement of gain, elevation and azimuth pattern shape, boresight error, cross-polarization levels, and phase vs. angle and frequency. For spaceborne SAR antennas of SEASAT size operating at C-band or higher, some of these measurements can become extremely difficult using conventional far-field antenna test ranges. Near-field scanning techniques offer an alternative approach and for C-band or X-band SARs, give much improved accuracy and precision as compared to that obtainable with a far-field approach.

  6. An Efficient Feedback Calibration Algorithm for Direct Imaging Radio Telescopes

    CERN Document Server

    Beardsley, Adam P; Bowman, Judd D; Morales, Miguel F

    2016-01-01

    We present the E-field Parallel Imaging Calibration (EPICal) algorithm, which addresses the need for a real-time calibration method for direct imaging radio astronomy correlators. Direct imaging involves a spatial fast Fourier transform of antenna voltages, alleviating the harsh $\\mathcal{O}(N_a^2)$ computational scaling to a more gentle $\\mathcal{O}(N_a \\log_2 N_a)$, which can save orders of magnitude in computation cost for next generation arrays consisting of hundreds to thousands of antennas. However, because signals are mixed in the correlator, gain correction must be applied on the front end. We develop the EPICal algorithm to form gain solutions in real time without ever forming visibilities. This method scales as the number of antennas, and produces results comparable to those from visibilities. Through simulations and application to Long Wavelength Array data we show this algorithm is a promising solution for next generation instruments.

  7. A Calibration and Mapping Pipeline for the Green Bank Telescope

    Science.gov (United States)

    Masters, J.; Garwood, B.; Langston, G.; Shelton, A.

    2011-07-01

    We present the first data calibration and spectral line mapping pipeline for the Green Bank Telescope (GBT), a 100 meter single-dish radio telescope operated by the National Radio Astronomy Observatory in West Virginia. The pipeline was developed for a prototype 7-pixel, K-band Focal Plane Array receiver (commissioned in the Fall of 2010) but is generalized for use with other receivers, operating at different wavelengths. One of the key design goals of the pipeline was to solve, on a smaller scale, issues that will arise with the entrance of the next generation of GBT detection equipment. New focal plane arrays, spectrometers and other instruments will produce much larger datasets, thus reinforcing the need for automated calibration and mapping. We discuss the implementation of the pipeline, near-term improvements and the issues we foresee as GBT hardware evolves over coming decade.

  8. Use of Radiometrically Calibrated Flat-Plate Calibrators in Calibration of Radiation Thermometers

    Science.gov (United States)

    Cárdenas-García, D.; Méndez-Lango, E.

    2015-08-01

    Most commonly used, low-temperature, infrared thermometers have large fields of view sizes that make them difficult to be calibrated with narrow aperture blackbodies. Flat-plate calibrators with large emitting surfaces have been proposed for calibrating these infrared thermometers. Because the emissivity of the flat plate is not unity, its radiance temperature is wavelength dependent. For calibration, the wavelength pass band of the device under test should match that of the reference infrared thermometer. If the device under test and reference radiometer have different pass bands, then it is possible to calculate the corresponding correction if the emissivity of the flat plate is known. For example, a correction of at is required when calibrating a infrared thermometer with a "" radiometrically calibrated flat-plate calibrator. A method is described for using a radiometrically calibrated flat-plate calibrator that covers both cases of match and mismatch working wavelength ranges of a reference infrared thermometer and infrared thermometers to be calibrated with the flat-plate calibrator. Also, an application example is included in this paper.

  9. A Simple Accelerometer Calibrator

    Science.gov (United States)

    Salam, R. A.; Islamy, M. R. F.; Munir, M. M.; Latief, H.; Irsyam, M.; Khairurrijal

    2016-08-01

    High possibility of earthquake could lead to the high number of victims caused by it. It also can cause other hazards such as tsunami, landslide, etc. In that case it requires a system that can examine the earthquake occurrence. Some possible system to detect earthquake is by creating a vibration sensor system using accelerometer. However, the output of the system is usually put in the form of acceleration data. Therefore, a calibrator system for accelerometer to sense the vibration is needed. In this study, a simple accelerometer calibrator has been developed using 12 V DC motor, optocoupler, Liquid Crystal Display (LCD) and AVR 328 microcontroller as controller system. The system uses the Pulse Wave Modulation (PWM) form microcontroller to control the motor rotational speed as response to vibration frequency. The frequency of vibration was read by optocoupler and then those data was used as feedback to the system. The results show that the systems could control the rotational speed and the vibration frequencies in accordance with the defined PWM.

  10. In-flight PSF calibration of the NuSTAR hard X-ray optics

    DEFF Research Database (Denmark)

    An, Hongjun; Madsen, Kristin K.; Westergaard, Niels J.;

    2014-01-01

    We present results of the point spread function (PSF) calibration of the hard X-ray optics of the Nuclear Spectroscopic Telescope Array (NuSTAR). Immediately post-launch, NuSTAR has observed bright point sources such as Cyg X-1, Vela X-1, and Her X-1 for the PSF calibration. We use the point sour...

  11. Feeding Your Teen Vegetarian

    Science.gov (United States)

    ... For Preschooler For Gradeschooler For Teen Feeding Your Teen Vegetarian By Mindy Hermann, MBA, RD Published July ... fries, soft drinks, desserts and candy. Have Your Teen Help "A vegetarian meal can be a healthy ...

  12. Probiotic in Ruminant Feed

    OpenAIRE

    Dicky Pamungkas; Yenny Nur Anggraeni

    2006-01-01

    The technology development of ruminant feed is related to the effort of fulfilling the nutrient requirement for maintenance and production of rumen microbes and optimizing the protein synthesis of rumen microbes, hence improving the animal production . Probiotic is widely used in feed to avoid the negative effect of antibiotic after therapeutic treatment and to be used as growth promoter . This paper describes the concept of probiotic, selection of microbes for probiotic, the benefit, the eff...

  13. Early Observations with The Murchison Widefield Array.

    Science.gov (United States)

    Mitchell, Daniel; MWA Collaboration

    2009-01-01

    The Murchison Widefield Array (MWA), one of the demonstrator projects for the Square Kilometre Array, is a next-generation radio telescope being built in Australia. The MWA will study cosmological reionization, the sun, space weather, and time variability of the radio sky between 80 and 300 MHz, with construction of the full 512-tile system to be complete by mid 2010. As is the case with other future large low-frequency arrays, the visibility data rate produced is extremely large; the correlator, with 3000 fully-polarized frequency channels, is 20 GB/s (a few Peta-Bytes/day). It is impractical to store data being generated at this rate, and software is currently being developed to calibrate the visibilities and form images from them in real time. Relatively rapid phase and polarization distortions due to the ionosphere set the cadence for the real-time system, with a complete cycle of calibration, imaging and image de-distortion completed every 8 seconds. Furthermore, the gain and polarization response of the antennas need to be measured and accounted for to reach the challenging dynamic range requirements. The software will run on-site on a high-throughput, real-time computing cluster, at several tera-flops. In the second half of 2008 and early 2009, a series of early observations are being carried out at the MWA site with new generation dipoles, beamformers and receivers. A major objective of these site visits will be to gather information on the antenna primary beams, the sky and the ionosphere, as we prepare to commission a sub-array constructed from the first 32 tiles in mid 2009. Data from these observations will also be used for testing of the real-time calibration and imaging system. In this poster we will present results from these early observations, with an emphasis on some of the main technical challenges.

  14. Calibration of a HTS Based LOX 400 mm Level Sensor

    Science.gov (United States)

    Karunanithi, R.; Jacob, S.; Nadig, D. S.; Prasad, M. V. N.; Gour, Abhay S.; Pankaj, S.; Gowthaman, M.; Sudharshan, H.

    The measurement of the cryogen level in a cryostage of space crafts is crucial. At the same time the weight of the sensor should be small as it affects the payload fraction of the space craft. An attempt to develop a HTS based level sensor of 400 mm for Liquid Oxygen (LOX) measurement was made. In the initial phase of testing, loss of superconductivity of HTS wire in LOX inside a cryostat was noticed. Thus, a new four wall cryostat was designed to have a stable LOX level to provide thermal stability to the HTS based LOX sensor. The calibration of the developed sensor was carried out against capacitance level sensor which was pre calibrated using diode array to verify its linearity and performance for different current excitation levels. The calibrations were carried out without heater wires. The automatic data logging was accomplished using a program developed in LabVIEW 11.0.

  15. A Generic Algorithm for IACT Optical Efficiency Calibration using Muons

    CERN Document Server

    Mitchell, A M W; Parsons, R D

    2015-01-01

    Muons produced in Extensive Air Showers (EAS) generate ring-like images in Imaging Atmospheric Cherenkov Telescopes when travelling near parallel to the optical axis. From geometrical parameters of these images, the absolute amount of light emitted may be calculated analytically. Comparing the amount of light recorded in these images to expectation is a well established technique for telescope optical efficiency calibration. However, this calculation is usually performed under the assumption of an approximately circular telescope mirror. The H.E.S.S. experiment entered its second phase in 2012, with the addition of a fifth telescope with a non-circular 600m$^2$ mirror. Due to the differing mirror shape of this telescope to the original four H.E.S.S. telescopes, adaptations to the standard muon calibration were required. We present a generalised muon calibration procedure, adaptable to telescopes of differing shapes and sizes, and demonstrate its performance on the H.E.S.S. II array.

  16. Axiom turkey genotyping array

    Science.gov (United States)

    The Axiom®Turkey Genotyping Array interrogates 643,845 probesets on the array, covering 643,845 SNPs. The array development was led by Dr. Julie Long of the USDA-ARS Beltsville Agricultural Research Center under a public-private partnership with Hendrix Genetics, Aviagen, and Affymetrix. The Turk...

  17. On chromatic and geometrical calibration

    DEFF Research Database (Denmark)

    Folm-Hansen, Jørgen

    1999-01-01

    we present the implementation of a complete calibration method for an accurate colour texture measurement device called VMX2000, the calibration for uneven laser sheet illumination in a flow measuring system and the use of automatic detection of calibration targets for a DLT/warping in a 3D PIV......The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how...

  18. Landsat-8 Thermal Infrared Sensor (TIRS Vicarious Radiometric Calibration

    Directory of Open Access Journals (Sweden)

    Julia A. Barsi

    2014-11-01

    the statistical assessment but indicate that the correction (particularly in band 11 is probably only valid for a subset of data. While the stray light effect is small enough in Band 10 to make the data useful across a wide array of applications, the effect in Band 11 is larger and the vicarious results suggest that Band 11 data should not be used where absolute calibration is required.

  19. Monopulse feed improves radar tracking accuracy

    Science.gov (United States)

    Lee-Yow, Clancy; Ghosh, Subir

    1992-03-01

    A monopulse antenna feed system based on a compact mode triplexer and a multimode corrugated horn is described. The system makes it possible to dramatically enhance the bandwidth and performance of space-fed array radars. Efficient microwave networking in the mode triplexer and a single aperture multimode corrugated horn provide independent control of RF excitation of the antenna aperture to achieve optimum distribution for the difference and sum beams simultaneously with a simple structure. The tracking acuracy is enhanced by the beam dependent effective size of the aperture in the multimode horn.

  20. Experiment of Injecting Phase Cal Ahead of the Feed: First Results

    Science.gov (United States)

    Ivanov, Dmitrij; Maslenikov, Anatolij; Vytnov, Alexander

    2010-01-01

    For developing the Russian VLBI network of new generation, a few experiments of injecting the phase calibration signal ahead of the feed were carried out. In the experiments an external broadband phase calibration signal was emitted through a special feed to a receiver horn directly. Prototypes of the feed for a frequency range of 2-18 GHz were created. The first experiments on injection phase cal ahead of the feed were carried out at Svetloe Observatory of the QUASAR VLBI network. The phase cal signal was emitted by the broadband feed installed on the roof of a mirror cabin, reflected by the sub-reflector, and received by the horn of the receiving system. The results of these experiments are considered.

  1. Calibration procedure for zenith plummets

    Directory of Open Access Journals (Sweden)

    Jelena GUČEVIĆ

    2013-09-01

    Full Text Available Zenith plummets are used mainly in applied geodesy, in civil engineering surveying, for materialization of the local vertical. The error of the vertical deflection of the instrument is directly transferred to the error of the observing construction. That is why a proper calibration procedure for the zenithlot is required. Metrological laboratory of the Faculty of Civil Engineering in Belgrade developed such calibration procedure. Here we present a mathematical model of the calibration and some selected results.

  2. Calibration procedure for zenith plummets

    OpenAIRE

    Jelena GUČEVIĆ; Delčev, Siniša; Vukan OGRIZOVIĆ

    2013-01-01

    Zenith plummets are used mainly in applied geodesy, in civil engineering surveying, for materialization of the local vertical. The error of the vertical deflection of the instrument is directly transferred to the error of the observing construction. That is why a proper calibration procedure for the zenithlot is required. Metrological laboratory of the Faculty of Civil Engineering in Belgrade developed such calibration procedure. Here we present a mathematical model of the calibration and som...

  3. Calibration of neutron albedo dosemeters.

    Science.gov (United States)

    Schwartz, R B; Eisenhauer, C M

    2002-01-01

    It is shown that by calibrating neutron albedo dosemeters under the proper conditions, two complicating effects will essentially cancel out, allowing accurate calibrations with no need for explicit corrections. The 'proper conditions' are: a large room (> or = 8 m on a side). use of a D2O moderated 252Cf source, and a source-to-phantom calibration distance of approximately 70 cm. PMID:12212898

  4. Timing calibration and spectral cleaning of LOFAR time series data

    Science.gov (United States)

    Corstanje, A.; Buitink, S.; Enriquez, J. E.; Falcke, H.; Hörandel, J. R.; Krause, M.; Nelles, A.; Rachen, J. P.; Schellart, P.; Scholten, O.; ter Veen, S.; Thoudam, S.; Trinh, T. N. G.

    2016-05-01

    We describe a method for spectral cleaning and timing calibration of short time series data of the voltage in individual radio interferometer receivers. It makes use of phase differences in fast Fourier transform (FFT) spectra across antenna pairs. For strong, localized terrestrial sources these are stable over time, while being approximately uniform-random for a sum over many sources or for noise. Using only milliseconds-long datasets, the method finds the strongest interfering transmitters, a first-order solution for relative timing calibrations, and faulty data channels. No knowledge of gain response or quiescent noise levels of the receivers is required. With relatively small data volumes, this approach is suitable for use in an online system monitoring setup for interferometric arrays. We have applied the method to our cosmic-ray data collection, a collection of measurements of short pulses from extensive air showers, recorded by the LOFAR radio telescope. Per air shower, we have collected 2 ms of raw time series data for each receiver. The spectral cleaning has a calculated optimal sensitivity corresponding to a power signal-to-noise ratio of 0.08 (or -11 dB) in a spectral window of 25 kHz, for 2 ms of data in 48 antennas. This is well sufficient for our application. Timing calibration across individual antenna pairs has been performed at 0.4 ns precision; for calibration of signal clocks across stations of 48 antennas the precision is 0.1 ns. Monitoring differences in timing calibration per antenna pair over the course of the period 2011 to 2015 shows a precision of 0.08 ns, which is useful for monitoring and correcting drifts in signal path synchronizations. A cross-check method for timing calibration is presented, using a pulse transmitter carried by a drone flying over the array. Timing precision is similar, 0.3 ns, but is limited by transmitter position measurements, while requiring dedicated flights.

  5. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed....

  6. Microprocessor-controlled photovoltaic-array loading unit

    Energy Technology Data Exchange (ETDEWEB)

    Russell, D.F.

    1982-08-01

    Described is a microprocessor-controlled test system in operation at the Photovoltaics Advanced Systems Test Facility located at Sandia National Laboratories. The test system is designed to measure the total energy output of photovoltaic arrays. The theory, installation, operation, and calibration of the test system are described.

  7. Radiological Calibration and Standards Facility

    Data.gov (United States)

    Federal Laboratory Consortium — PNNL maintains a state-of-the-art Radiological Calibration and Standards Laboratory on the Hanford Site at Richland, Washington. Laboratory staff provide expertise...

  8. Study on fast calibration of a ULA's gain and phase error

    Institute of Scientific and Technical Information of China (English)

    ZHU Guang-ping; SUN Hui; ZHANG Ming-hui

    2007-01-01

    Array calibration is important in engineering practice. In this paper, fast calibration methods for a ULA's gain and phase errors both in far and near fields are proposed. In the far field, using a single sound source without exact orientation, this method horizontally rotates the array exactly once, performs eigen value decomposition for the covariance matrix of received data, then computes the gain and phase error according to the formulas. In the near field, using the same single sound source, it is necessary to rotate the array horizontally at most three times, build equations according to geometric relations, then solve them. Using the formula proposed in this paper, spherical waves are modified into plane waves.Then eigen values decomposition is performed. These two calibration methods were shown to be valid by simulation and are fast, accurate and easy to use. Finally, an analysis of factors influencing estimation precision is given.

  9. RX130 Robot Calibration

    Science.gov (United States)

    Fugal, Mario

    2012-10-01

    In order to create precision magnets for an experiment at Oak Ridge National Laboratory, a new reverse engineering method has been proposed that uses the magnetic scalar potential to solve for the currents necessary to produce the desired field. To make the magnet it is proposed to use a copper coated G10 form, upon which a drill, mounted on a robotic arm, will carve wires. The accuracy required in the manufacturing of the wires exceeds nominal robot capabilities. However, due to the rigidity as well as the precision servo motor and harmonic gear drivers, there are robots capable of meeting this requirement with proper calibration. Improving the accuracy of an RX130 to be within 35 microns (the accuracy necessary of the wires) is the goal of this project. Using feedback from a displacement sensor, or camera and inverse kinematics it is possible to achieve this accuracy.

  10. A Multiple Beamforming Network for Unequally Spaced Linear Array Based on CORPS

    Directory of Open Access Journals (Sweden)

    Armando Arce

    2015-01-01

    Full Text Available This paper proposes an alternative and innovative way to design a simpler beamforming network (BFN based on balancing alternated power combiners and dividers, to feed a nonuniformly spaced linear array with Gaussian amplitude and coherent (in-phase signals. Thus, a two-beam design configuration of the feeding network for a nonuniform array with beam steering capability is proposed and analyzed. The nonuniform aperture and the complex inputs of the feeding network are optimized by means of a differential evolution algorithm. In addition, a comparative analysis between a uniform and nonuniform linear array with the proposed feeding network is performed. Simulation results show the advantages and effectiveness of the proposed feeding network exploiting the nonuniformity of the antenna elements, in terms of side lobe level and directivity. Furthermore, research results show an inherent reduction in hardware complexity of the network.

  11. TOD to TTP calibration

    Science.gov (United States)

    Bijl, Piet; Reynolds, Joseph P.; Vos, Wouter K.; Hogervorst, Maarten A.; Fanning, Jonathan D.

    2011-05-01

    The TTP (Targeting Task Performance) metric, developed at NVESD, is the current standard US Army model to predict EO/IR Target Acquisition performance. This model however does not have a corresponding lab or field test to empirically assess the performance of a camera system. The TOD (Triangle Orientation Discrimination) method, developed at TNO in The Netherlands, provides such a measurement. In this study, we make a direct comparison between TOD performance for a range of sensors and the extensive historical US observer performance database built to develop and calibrate the TTP metric. The US perception data were collected doing an identification task by military personnel on a standard 12 target, 12 aspect tactical vehicle image set that was processed through simulated sensors for which the most fundamental sensor parameters such as blur, sampling, spatial and temporal noise were varied. In the present study, we measured TOD sensor performance using exactly the same sensors processing a set of TOD triangle test patterns. The study shows that good overall agreement is obtained when the ratio between target characteristic size and TOD test pattern size at threshold equals 6.3. Note that this number is purely based on empirical data without any intermediate modeling. The calibration of the TOD to the TTP is highly beneficial to the sensor modeling and testing community for a variety of reasons. These include: i) a connection between requirement specification and acceptance testing, and ii) a very efficient method to quickly validate or extend the TTP range prediction model to new systems and tasks.

  12. Calibration of Nanopositioning Stages

    Directory of Open Access Journals (Sweden)

    Ning Tan

    2015-12-01

    Full Text Available Accuracy is one of the most important criteria for the performance evaluation of micro- and nanorobots or systems. Nanopositioning stages are used to achieve the high positioning resolution and accuracy for a wide and growing scope of applications. However, their positioning accuracy and repeatability are not well known and difficult to guarantee, which induces many drawbacks for many applications. For example, in the mechanical characterisation of biological samples, it is difficult to perform several cycles in a repeatable way so as not to induce negative influences on the study. It also prevents one from controlling accurately a tool with respect to a sample without adding additional sensors for closed loop control. This paper aims at quantifying the positioning repeatability and accuracy based on the ISO 9283:1998 standard, and analyzing factors influencing positioning accuracy onto a case study of 1-DoF (Degree-of-Freedom nanopositioning stage. The influence of thermal drift is notably quantified. Performances improvement of the nanopositioning stage are then investigated through robot calibration (i.e., open-loop approach. Two models (static and adaptive models are proposed to compensate for both geometric errors and thermal drift. Validation experiments are conducted over a long period (several days showing that the accuracy of the stage is improved from typical micrometer range to 400 nm using the static model and even down to 100 nm using the adaptive model. In addition, we extend the 1-DoF calibration to multi-DoF with a case study of a 2-DoF nanopositioning robot. Results demonstrate that the model efficiently improved the 2D accuracy from 1400 nm to 200 nm.

  13. Ku-Band Traveling Wave Slot Array Using Simple Scanning Control

    Science.gov (United States)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

    2015-01-01

    This paper introduces a feeding concept aimed at simplifying the backend (phase shifters) of traditional phased arrays. As an alternative to traditional phased arrays, we employ a traveling wave array (TWA) using a single feedline whose propagation constant is controlled via a single, small mechanical movement without a need for phase shifters to enable scanning. Specifically, a dielectric plunger is positioned within a parallel plate waveguide (PPW) transmission line (TL) that feeds the TWA. By adjusting the position of the dielectric plunger within the PPW feeding the TWA, beam steering is achieved. A 20 element array is designed at 13GHz shown to give stable realized gain across the angular range of -25 deg. less than or equal to theta less than or equal to 25 deg. A proof of concept array is fabricated and measured to demonstrate and validate the concept's operation.

  14. Early Observations with the Expanded Owens Valley Solar Array

    Science.gov (United States)

    Gary, Dale E.

    2016-05-01

    The Expanded Owens Valley Solar Array (EOVSA) is a newly expanded and upgraded, solar-dedicated radio array consisting of 13 antennas of 2.1 m diameter equipped with receivers designed to cover the 1-18 GHz frequency range. Two large (27-m diameter) dishes are being outfitted with He-cooled receivers for use in calibration of the small dishes. During 2015, the array obtained observations from dozens of flares in total power mode on 8 antennas. Since February 2016, it has begun taking solar data on all 13 small antennas with full interferometric correlations, as well as calibration observations with the first of the two large antennas equipped with its He-cooled receiver. The second He-cooled receiver is nearly complete, and will be available around the time of the meeting. We briefly review the commissioning activities leading up to full operations, including polarization and gain measurements and calibration methods, and resulting measures of array performance. We then present some early imaging observations with the array, emphasizing the remarkable temporal and spectral resolution of the instrument, together with joint RHESSI hard X-ray and SDO EUV observations.

  15. Incompatible Ages for Clearwing Butterflies Based on Alternative Secondary Calibrations.

    Science.gov (United States)

    Garzón-Orduña, Ivonne J; Silva-Brandão, Karina L; Willmott, Keith R; Freitas, André V L; Brower, Andrew V Z

    2015-09-01

    The recent publication of a time-tree for the plant family Solanaceae (nightshades) provides the opportunity to use independent calibrations to test divergence times previously inferred for the diverse Neotropical butterfly tribe Ithomiini. Ithomiini includes clades that are obligate herbivores of Solanaceae, with some genera feeding on only one genus. We used 8 calibrations extracted from the plant tree in a new relaxed molecular-clock analysis to produce an alternative temporal framework for the diversification of ithomiines. We compared the resulting age estimates to: (i) a time-tree obtained using 7 secondary calibrations from the Nymphalidae tree of Wahlberg et al. (2009), and (ii) Wahlberg et al.'s (2009) original age estimates for the same clades. We found that Bayesian clock estimates were rather sensitive to a variety of analytical parameters, including taxon sampling. Regardless of this sensitivity however, ithomiine divergence times calibrated with the ages of nightshades were always on average half the age of previous estimates. Younger dates for ithomiine clades appear to fit better with factors long suggested to have promoted diversification of the group such as the uplifting of the Andes, in the case of montane genera. Alternatively, if ithomiines are as old as previous estimates suggest, the recent ages inferred for the diversification of Solanaceae seem likely to be seriously underestimated. Our study exemplifies the difficulty of testing hypotheses of divergence times and of choosing between alternative dating scenarios, and shows that age estimates based on seemingly plausible calibrations may be grossly incongruent.

  16. Calibration of the microcalorimeter spectrometer on-board the Hitomi (Astro-H) observatory (invited)

    Science.gov (United States)

    Eckart, M. E.; Boyce, K. R.; Brown, G. V.; Chiao, M. P.; Fujimoto, R.; Haas, D.; den Herder, J.-W.; Ishisaki, Y.; Kelley, R. L.; Kilbourne, C. A.; Leutenegger, M. A.; McCammon, D.; Mitsuda, K.; Porter, F. S.; Sawada, M.; Sneiderman, G. A.; Szymkowiak, A. E.; Takei, Y.; Tashiro, M.; Tsujimoto, M.; de Vries, C. P.; Watanabe, T.; Yamada, S.; Yamasaki, N. Y.

    2016-11-01

    The Hitomi Soft X-ray Spectrometer (SXS) was a pioneering non-dispersive imaging x-ray spectrometer with 5 eV FWHM energy resolution, consisting of an array of 36 silicon-thermistor microcalorimeters at the focus of a high-throughput soft x-ray telescope. The instrument enabled astrophysical plasma diagnostics in the 0.3-12 keV band. We introduce the SXS calibration strategy and corresponding ground calibration measurements that took place from 2012-2015, including both the characterization of the microcalorimeter array and measurements of the x-ray transmission of optical blocking filters.

  17. Tectonic calibrations in molecular dating

    Institute of Scientific and Technical Information of China (English)

    Ullasa KODANDARAMAIAH

    2011-01-01

    Molecular dating techniques require the use of calibrations, which are usually fossil or geological vicariance-based.Fossil calibrations have been criticised because they result only in minimum age estimates. Based on a historical biogeographic perspective, Ⅰ suggest that vicariance-based calibrations are more dangerous. Almost all analytical methods in historical biogeography are strongly biased towards inferring vicariance, hence vicariance identified through such methods is unreliable. Other studies, especially of groups found on Gondwanan fragments, have simply assumed vicariance. Although it was previously believed that vicariance was the predominant mode of speciation, mounting evidence now indicates that speciation by dispersal is common, dominating vicariance in several groups. Moreover, the possibility of speciation having occurred before the said geological event cannot be precluded. Thus, geological calibrations can under- or overestimate times, whereas fossil calibrations always result in minimum estimates. Another major drawback of vicariant calibrations is the problem of circular reasoning when the resulting estimates are used to infer ages of biogeographic events. Ⅰ argue that fossil-based dating is a superior alternative to vicariance, primarily because the strongest assumption in the latter, that speciation was caused by the said geological process, is more often than not the most tenuous. When authors prefer to use a combination of fossil and vicariant calibrations, one suggestion is to report results both with and without inclusion of the geological constraints. Relying solely on vicariant calibrations should be strictly avoided.

  18. Cannabis and Breast feeding

    International Nuclear Information System (INIS)

    Cannabis is a drug derived from hemp plant, Cannabis sativa, used both as a recreational drug or as medicine. It is a widespread illegal substance, generally smoked for its hallucinogenic properties. Little is known about the adverse effects of postnatal cannabis exposure throw breast feeding because of a lack of studies in lactating women. The active substance of cannabis is the delta 9 Tetrahydrocannabinol (THC). Some studies conclude that it could decrease motor development of the child at one year of age. Therefore, cannabis use and abuse of other drugs like alcohol, tobacco, or cocaine must be contraindicated during breast feeding. Mothers who use cannabis must stop breast feeding, or ask for medical assistance to stop cannabis use in order to provide her baby with all the benefits of human milk.

  19. The Advanced LIGO Photon Calibrators

    CERN Document Server

    Karki, S; Kandhasamy, S; Abbott, B P; Abbott, T D; Anders, E H; Berliner, J; Betzwieser, J; Daveloza, H P; Cahillane, C; Canete, L; Conley, C; Gleason, J R; Goetz, E; Kissel, J S; Izumi, K; Mendell, G; Quetschke, V; Rodruck, M; Sachdev, S; Sadecki, T; Schwinberg, P B; Sottile, A; Wade, M; Weinstein, A J; West, M; Savage, R L

    2016-01-01

    The two interferometers of the Laser Interferometry Gravitaional-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events, and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as Photon Calibrators. These systems, which were completely redesigned for Advanced LIGO, include several significant upgrades that enable them to meet the calibration requirements of second-generation gravitational wave detectors in the new era of gravitational-wave astronomy. We report on the design, implementation, and operation of these Advanced LIGO Photon Calibrators that are currently providing fiducial displacements on the order of $10^{-18}$ m/$\\sqrt{\\textrm{Hz}}$ with accuracy and precision of better ...

  20. Antenna Calibration and Measurement Equipment

    Science.gov (United States)

    Rochblatt, David J.; Cortes, Manuel Vazquez

    2012-01-01

    A document describes the Antenna Calibration & Measurement Equipment (ACME) system that will provide the Deep Space Network (DSN) with instrumentation enabling a trained RF engineer at each complex to perform antenna calibration measurements and to generate antenna calibration data. This data includes continuous-scan auto-bore-based data acquisition with all-sky data gathering in support of 4th order pointing model generation requirements. Other data includes antenna subreflector focus, system noise temperature and tipping curves, antenna efficiency, reports system linearity, and instrument calibration. The ACME system design is based on the on-the-fly (OTF) mapping technique and architecture. ACME has contributed to the improved RF performance of the DSN by approximately a factor of two. It improved the pointing performances of the DSN antennas and productivity of its personnel and calibration engineers.

  1. Design, manufacture, and calibration of infrared radiometric blackbody sources

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, D.A.; Michaud, F.D.; Bender, S.C. [and others

    1996-04-01

    A Radiometric Calibration Station (RCS) is being assembled at the Los Alamos National Laboratories (LANL) which will allow for calibration of sensors with detector arrays having spectral capability from about 0.4-15 {mu}m. The configuration of the LANL RCS. Two blackbody sources have been designed to cover the spectral range from about 3-15 {mu}m, operating at temperatures ranging from about 180-350 K within a vacuum environment. The sources are designed to present a uniform spectral radiance over a large area to the sensor unit under test. The thermal uniformity requirement of the blackbody cavities has been one of the key factors of the design, requiring less than 50 mK variation over the entire blackbody surface to attain effective emissivity values of about 0.999. Once the two units are built and verified to the level of about 100 mK at LANL, they will be sent to the National Institute of Standards and Technology (NIST), where at least a factor of two improvement will be calibrated into the blackbody control system. The physical size of these assemblies will require modifications of the existing NIST Low Background Infrared (LBIR) Facility. LANL has constructed a bolt-on addition to the LBIR facility that will allow calibration of our large aperture sources. Methodology for attaining the two blackbody sources at calibrated levels of performance equivalent to present state of the art will be explained in the following.

  2. Accurate DOA Estimations Using Microstrip Adaptive Arrays in the Presence of Mutual Coupling Effect

    Directory of Open Access Journals (Sweden)

    Qiulin Huang

    2013-01-01

    Full Text Available A new mutual coupling calibration method is proposed for adaptive antenna arrays and is employed in the DOA estimations to calibrate the received signals. The new method is developed via the transformation between the embedded element patterns and the isolated element patterns. The new method is characterized by the wide adaptability of element structures such as dipole arrays and microstrip arrays. Additionally, the new method is suitable not only for the linear polarization but also for the circular polarization. It is shown that accurate calibration of the mutual coupling can be obtained for the incident signals in the 3 dB beam width and the wider angle range, and, consequently, accurate [1D] and [2D] DOA estimations can be obtained. Effectiveness of the new calibration method is verified by a linearly polarized microstrip ULA, a circularly polarized microstrip ULA, and a circularly polarized microstrip UCA.

  3. Series-Fed Microstrip Array Antenna with Circular Polarization

    Directory of Open Access Journals (Sweden)

    Tuan-Yung Han

    2012-01-01

    Full Text Available This study proposes a novel 2 × 2 array antenna design with broadband and circularly-polarized (CP operation. The proposed design uses a simple series-fed network to increase the CP bandwidth without requiring one-by-one adjustment of each array element or a complex feed network. Selecting the appropriate spacing between each array element allows the proposed array antenna to generate CP radiation with a low axial ratio. Experimental results based on a prototype show that this 2 × 2 microstrip array antenna achieves a wide 3 dB axial ratio bandwidth of more than 10%. Simulated data are also provided to confirm the measured results.

  4. Approach for wideband direction-of-arrival estimation in the presence of array model errors

    Institute of Scientific and Technical Information of China (English)

    Chen Deli; Zhang Cong; Tao Huamin; Lu Huanzhang

    2009-01-01

    The presence of array imperfection and mutual coupling in sensor arrays poses several challenges for development of effective algorithms for the direction-of-arrival (DOA) estimation problem in array processing. A correlation domain wideband DOA estimation algorithm without array calibration is proposed, to deal with these array model errors, using the arbitrary antenna array of omnidirectional elements. By using the matrix operators that have the memory and oblivion characteristics, this algorithm can separate the incident signals effectively. Compared with other typical wideband DOA estimation algorithms based on the subspace theory, this algorithm can get robust DOA estimation with regard to position error, gain-phase error, and mutual coupling, by utilizing a relaxation technique based on signal separation. The signal separation category and the robustness of this algorithm to the array model errors are analyzed and proved. The validity and robustness of this algorithm, in the presence of array model errors, are confirmed by theoretical analysis and simulation results.

  5. A calibrated Franklin chimes

    Science.gov (United States)

    Gonta, Igor; Williams, Earle

    1994-05-01

    Benjamin Franklin devised a simple yet intriguing device to measure electrification in the atmosphere during conditions of foul weather. He constructed a system of bells, one of which was attached to a conductor that was suspended vertically above his house. The device is illustrated in a well-known painting of Franklin (Cohen, 1985). The elevated conductor acquired a potential due to the electric field in the atmosphere and caused a brass ball to oscillate between two bells. The purpose of this study is to extend Franklin's idea by constructing a set of 'chimes' which will operate both in fair and in foul weather conditions. In addition, a mathematical relationship will be established between the frequency of oscillation of a metallic sphere in a simplified geometry and the potential on one plate due to the electrification of the atmosphere. Thus it will be possible to calibrate the 'Franklin Chimes' and to obtain a nearly instantaneous measurement of the potential of the elevated conductor in both fair and foul weather conditions.

  6. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  7. Pacific Array (Transportable Broadband Ocean Floor Array)

    Science.gov (United States)

    Kawakatsu, Hitoshi; Ekstrom, Goran; Evans, Rob; Forsyth, Don; Gaherty, Jim; Kennett, Brian; Montagner, Jean-Paul; Utada, Hisashi

    2016-04-01

    Based on recent developments on broadband ocean bottom seismometry, we propose a next generation large-scale array experiment in the ocean. Recent advances in ocean bottom broadband seismometry1, together with advances in the seismic analysis methodology, have enabled us to resolve the regional 1-D structure of the entire lithosphere/asthenosphere system, including seismic anisotropy (azimuthal, and hopefully radial), with deployments of ~15 broadband ocean bottom seismometers (BBOBSs). Having ~15 BBOBSs as an array unit for a 2-year deployment, and repeating such deployments in a leap-frog way or concurrently (an array of arrays) for a decade or so would enable us to cover a large portion of the Pacific basin. Such efforts, not only by giving regional constraints on the 1-D structure beneath Pacific ocean, but also by sharing waveform data for global scale waveform tomography, would drastically increase our knowledge of how plate tectonics works on this planet, as well as how it worked for the past 150 million years. International collaborations is essential: if three countries/institutions participate this endeavor together, Pacific Array may be accomplished within five-or-so years.

  8. Radio detection of high-energy cosmic rays with the Auger Engineering Radio Array (PISA 2015)

    CERN Document Server

    Schröder, Frank G

    2016-01-01

    The Auger Engineering Radio Array (AERA) is an enhancement of the Pierre Auger Observatory in Argentina. Covering about View the $17\\,$km$^2$, AERA is the world-largest antenna array for cosmic-ray observation. It consists of more than 150 antenna stations detecting the radio signal emitted by air showers, i.e., cascades of secondary particles caused by primary cosmic rays hitting the atmosphere. At the beginning, technical goals had been in focus: first of all, the successful demonstration that a large-scale antenna array consisting of autonomous stations is feasible. Moreover, techniques for calibration of the antennas and time calibration of the array have been developed, as well as special software for the data analysis. Meanwhile physics goals come into focus. At the Pierre Auger Observatory air showers are simultaneously detected by several detector systems, in particular water-Cherenkov detectors at the surface, underground muon detectors, and fluorescence telescopes, which enables cross-calibration of...

  9. NICHE: The Non-Imaging CHErenkov Array

    CERN Document Server

    Bergman, Douglas

    2012-01-01

    The accurate measurement of the Cosmic Ray (CR) nuclear composition around and above the Knee (~ 10^15.5 eV) has been difficult due to uncertainties inherent to the measurement techniques and/or dependence on hadronic Monte Carlo simulation models required to interpret the data. Measurement of the Cherenkov air shower signal, calibrated with air fluorescence measurements, offers a methodology to provide an accurate measurement of the nuclear composition evolution over a large energy range. NICHE will use an array of widely-spaced, non-imaging Cherenkov counters to measure the amplitude and time-spread of the air shower Cherenkov signal to extract CR nuclear composition measurements and to cross-calibrate the Cherenkov energy and composition measurements with TA/TALE fluorescence and surface detector measurements.

  10. Mercury Continuous Emmission Monitor Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John Schabron; Eric Kalberer; Ryan Boysen; William Schuster; Joseph Rovani

    2009-03-12

    Mercury continuous emissions monitoring systems (CEMs) are being implemented in over 800 coal-fired power plant stacks throughput the U.S. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor calibrators/generators. These devices are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 and vacated by a Federal appeals court in early 2008 required that calibration be performed with NIST-traceable standards. Despite the vacature, mercury emissions regulations in the future will require NIST traceable calibration standards, and EPA does not want to interrupt the effort towards developing NIST traceability protocols. The traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued a conceptual interim traceability protocol for elemental mercury calibrators. The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The EPA traceability protocol document is divided into two separate sections. The first deals with the qualification of calibrator models by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the calibrators that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma

  11. Application of the FD-TD method to the electromagnetic modeling of patch antenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Pasik, M.F. [Sandia National Labs., Albuquerque, NM (United States); Aguirre, G.; Cangellaris, A.C. [Univ. of Arizona, Tucson, AZ (United States). Dept. of Electrical and Computer Eengineering, Center for Electronic Packaging Research

    1996-01-10

    FD-TD method and the Berenger Perfectly Matched Layer (PML) absorbing condition are applied to the modeling of a 32-element patch array. Numerical results for the return loss at the array feed are presented and compared to measured results for the purpose of model validation.

  12. Telescope Array Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, H.; Yoshida, S. [Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522 (Japan); Yoshii, H. [Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577 (Japan); Tanaka, K. [Hiroshinma City University, 3-4-1 Ozuka-Higashi, Asa-Minami-ku, Hiroshima, 731-3194 (Japan); Cohen, F.; Fukushima, M.; Hayashida, N.; Hiyama, K.; Ikeda, D.; Kido, E.; Kondo, Y.; Nonaka, T.; Ohnishi, M.; Ohoka, H.; Ozawa, S.; Sagawa, H.; Sakurai, N.; Shibata, T.; Shimodaira, H.; Takeda, M. [ICRR, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan)] (and others)

    2008-01-15

    The TA observatory is a hybrid detector system consisting of both a surface detector array as well as a set of fluorescence detectors. The observatory will measure the energy spectrum, anisotropy and composition of ultra-high energy cosmic rays. The surface detectors are being deployed and the array should be complete by the end of February, 2007. We will soon be collecting hybrid data at the Telecope Array.

  13. Ka-Band Monopulse Antenna Pointing Calibration Using Wideband Radio Sources

    Science.gov (United States)

    Buu, C.; Calvo, J.; Cheng, T.-H.; Vazquez, M.

    2010-08-01

    A new method of performing a system end-to-end monopulse antenna calibration using widely available wideband astronomical radio sources is presented as an alternative to the current method of using a spacecraft signal. Current monopulse calibration requires a spacecraft carrier signal to measure amplitude and phase differences in the monopulse feed and low-noise amplifiers (LNAs). The alternative method presented here will allow the ground station to perform monopulse calibrations during maintenance periods instead of spacecraft track time, and provide an end-to-end system check-out capability without requiring a spacecraft signal. In this article, we give an overview of the current calibration approach, describe a new method for calibrating with radio sources, and present results from field testing of this new method.

  14. Feeding of Diarmis Proboscis

    Science.gov (United States)

    Young, Jocelyn

    2005-01-01

    The feeding of Diarmis proboscis is an exciting outdoor laboratory activity that demonstrates a single concept of adaptations--cryptic colorations. The students are "transformed" into D. proboscis (no Harry Potter magic needed) in order to learn how adaptations work in the natural world. Prior to beginning this activity, students should have a…

  15. Feed sources for livestock

    NARCIS (Netherlands)

    Zanten, van H.H.E.

    2016-01-01

    Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way. Cu

  16. Low Emission Feed

    NARCIS (Netherlands)

    Klop, G.

    2016-01-01

    Research into manipulating methane (CH4) production as a result of enteric fermentation in ruminants currently receives global interest. Using feed additives may be a feasible strategy to mitigate CH4 as they are supplied in such amounts that the basal diet composition will not be largely affected.

  17. Integrated avalanche photodiode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, Eric S.

    2015-07-07

    The present disclosure includes devices for detecting photons, including avalanche photon detectors, arrays of such detectors, and circuits including such arrays. In some aspects, the detectors and arrays include a virtual beveled edge mesa structure surrounded by resistive material damaged by ion implantation and having side wall profiles that taper inwardly towards the top of the mesa structures, or towards the direction from which the ion implantation occurred. Other aspects are directed to masking and multiple implantation and/or annealing steps. Furthermore, methods for fabricating and using such devices, circuits and arrays are disclosed.

  18. Embedded calibration system for the DIII-D Langmuir probe analog fiber optic linksa)

    Science.gov (United States)

    Watkins, J. G.; Rajpal, R.; Mandaliya, H.; Watkins, M.; Boivin, R. L.

    2012-10-01

    This paper describes a generally applicable technique for simultaneously measuring offset and gain of 64 analog fiber optic data links used for the DIII-D fixed Langmuir probes by embedding a reference voltage waveform in the optical transmitted signal before every tokamak shot. The calibrated data channels allow calibration of the power supply control fiber optic links as well. The array of fiber optic links and the embedded calibration system described here makes possible the use of superior modern data acquisition electronics in the control room.

  19. Embedded calibration system for the DIII-D Langmuir probe analog fiber optic links

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, J. G. [Sandia National Laboratories, Livermore, California (United States); Rajpal, R.; Mandaliya, H. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat (India); Watkins, M.; Boivin, R. L. [General Atomics, San Diego, California (United States)

    2012-10-15

    This paper describes a generally applicable technique for simultaneously measuring offset and gain of 64 analog fiber optic data links used for the DIII-D fixed Langmuir probes by embedding a reference voltage waveform in the optical transmitted signal before every tokamak shot. The calibrated data channels allow calibration of the power supply control fiber optic links as well. The array of fiber optic links and the embedded calibration system described here makes possible the use of superior modern data acquisition electronics in the control room.

  20. Application of the Langley plot for calibration of sun sensors for the Halogen Occultation Experiment (HALOE)

    Science.gov (United States)

    Moore, Alvah S., Jr.; Mauldin, L. ED, III; Stump, Charles W.; Reagan, John A.; Fabert, Milton G.

    1989-01-01

    The calibration of the Halogen Occultation Experiment (HALOE) sun sensor is described. This system consists of two energy-balancing silicon detectors which provide coarse azimuth and elevation control signals and a silicon photodiode array which provides top and bottom solar edge data for fine elevation control. All three detectors were calibrated on a mountaintop near Tucson, Ariz., using the Langley plot technique. The conventional Langley plot technique was modified to allow calibration of the two coarse detectors, which operate wideband. A brief description of the test setup is given. The HALOE instrument is a gas correlation radiometer that is now being developed for the Upper Atmospheric Research Satellite.

  1. The 74MHz System on the Very Large Array

    CERN Document Server

    Kassim, N E; Erickson, W C; Perley, R A; Cotton, W D; Greisen, E W; Cohen, A S; Hicks, B; Schmitt, H R; Katz, D

    2007-01-01

    The Naval Research Laboratory and the National Radio Astronomy Observatory completed implementation of a low frequency capability on the VLA at 73.8 MHz in 1998. This frequency band offers unprecedented sensitivity (~25 mJy/beam) and resolution (~25 arcsec) for low-frequency observations. We review the hardware, the calibration and imaging strategies, comparing them to those at higher frequencies, including aspects of interference excision and wide-field imaging. Ionospheric phase fluctuations pose the major difficulty in calibrating the array. Over restricted fields of view or at times of extremely quiescent ionospheric ``weather'', an angle-invariant calibration strategy can be used. In this approach a single phase correction is devised for each antenna, typically via self-calibration. Over larger fields of view or at times of more normal ionospheric ``weather'' when the ionospheric isoplanatic patch size is smaller than the field of view, we adopt a field-based strategy in which the phase correction depend...

  2. Compact Microstrip Feeding Network for Mobile Base Station Antenna

    Directory of Open Access Journals (Sweden)

    Mohamed S. El-gendy, Haythem H. Abdullah, Esmat A. Abdallah

    2016-07-01

    Full Text Available Most mobile base station antennas constituted from an array of radiating elements fed by a feeding network circuit that satisfy shaping the radiation pattern to meet the desired specifications. In this paper, a feeding network circuit is designed to feed mobile base station antenna array. The number of antenna array elements that satisfies the desired beamwidth and side lobe level is ten. The base station antenna covers the operating band from 0.2 GHz to 2.57 GHz, so it supports GSM380, GSM410, GSM450, GSM480, GSM 710, GSM750, GSM810, GSM850, GSM900, GSM1800 / DCS1800, GSM1900 / PCS1900, UMTS2100, and some used LTE bands. Two feeding circuits are designed one for lower band that extends from 200 MHz to 960 MHz and the other is used for upper band that extends from 1.71 GHz to 2.17 GHz. A compact dual-band microstrip equal Wilkinson power divider looks like zigzag shape yields a size reduction of 45.68 % than the conventional shape is utilized in the feeding network circuit. Two cascaded stages of unequal Wilkinson power divider (UWPD with certain power division ratios at the out ports are proposed. A three unit hippocampus - shaped defected ground structure (DGS pattern etched on the ground plane and placed underneath one of the microstrip branch line of both cascaded unequal Wilkinson power divider is used to realize 102 Ω lines with a wider width of 1.6 mm. The feeding network is designed and fabricated on FR4 dielectric substrate with dielectric constant of εr = 4.5, loss tangent 0.025 and substrate height of 1.5 mm.

  3. Mexican national pyronometer network calibration

    Science.gov (United States)

    VAldes, M.; Villarreal, L.; Estevez, H.; Riveros, D.

    2013-12-01

    In order to take advantage of the solar radiation as an alternate energy source it is necessary to evaluate the spatial and temporal availability. The Mexican National Meterological Service (SMN) has a network with 136 meteorological stations, each coupled with a pyronometer for measuring the global solar radiation. Some of these stations had not been calibrated in several years. The Mexican Department of Energy (SENER) in order to count on a reliable evaluation of the solar resource funded this project to calibrate the SMN pyrometer network and validate the data. The calibration of the 136 pyronometers by the intercomparison method recommended by the World Meterological Organization (WMO) requires lengthy observations and specific environmental conditions such as clear skies and a stable atmosphere, circumstances that determine the site and season of the calibration. The Solar Radiation Section of the Instituto de Geofísica of the Universidad Nacional Autónoma de México is a Regional Center of the WMO and is certified to carry out the calibration procedures and emit certificates. We are responsible for the recalibration of the pyronometer network of the SMN. A continuous emission solar simulator with exposed areas with 30cm diameters was acquired to reduce the calibration time and not depend on atmospheric conditions. We present the results of the calibration of 10 thermopile pyronometers and one photovoltaic cell by the intercomparison method with more than 10000 observations each and those obtained with the solar simulator.

  4. The future of fluorescence sensor arrays.

    Science.gov (United States)

    Demchenko, Alexander P

    2005-09-01

    The rapid progress in sensor and biosensor array technologies needs a general strategy in the design of fluorescence reporters. Such reporters should provide a high density of sensor elements, allow analysis of targets of different affinities, and be internally calibrated, reproducible and have a rapid readout. Several criteria are introduced here for the comparative evaluation of fluorescence-sensing techniques. It is shown that only the two-band wavelength ratiometric sensing with a single reporter dye exhibiting rapid reversible excited-state reaction can satisfy all these criteria and is a prospective candidate for further development. PMID:15967523

  5. Pierre Auger Observatory and Telescope Array: Joint Contributions to the 33rd International Cosmic Ray Conference (ICRC 2013)

    CERN Document Server

    Array, The Telescope; Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Chae, M J; Cheon, B G; Chiba, J; Chikawa, M; Cho, W R; Fujii, T; Fukushima, M; Goto, K; Hanlon, W; Hayashi, Y; Hayashida, N; Hibino, K; Honda, K; Ikeda, D; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kawata, K; Kido, E; Kim, H B; Kim, J H; Kitamura, S; Kitamura, Y; Kuzmin, V; Kwon, Y J; Lan, J; Lundquist, J P; Machida, K; Martens, K; Matsuda, T; Matsuyama, T; Matthews, J N; Minamino, M; Mukai, K; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nanpei, H; Nonaka, T; Nozato, A; Ogio, S; Oh, S; Ohnishi, M; Ohoka, H; Oki, K; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shirahama, T; Smith, J D; Sokolsky, P; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T A; Takamura, M; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Uchihori, Y; Udo, S; Urban, F; Vasiloff, G; Wada, Y; Wong, T; Yamaoka, H; Yamazaki, K; Yang, J; Yashiro, K; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z; Aab, A; Abreu, P; Aglietta, M; Ahlers, M; Ahn, E J; Albuquerque, I F M; Allekotte, I; Allen, J; Allison, P; Almela, A; Castillo, J Alvarez; Alvarez-Muniz, J; Batista, R Alves; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Antivcic, T; Aramo, C; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Badescu, A M; Barber, K B; Bardenet, R; Baeuml, J; Baus, C; Beatty, J J; Becker, K H; Belletoile, A; Bellido, J A; BenZvi, S; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, F; Blanco, M; Bleve, C; Blumer, H; Bohacova, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brancus, I; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Burton, R E; Buscemi, M; Caballero-Mora, K S; Caccianiga, B; Caccianiga, L; Candusso, M; Caramete, L; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Cheng, S H; Chiavassa, A; Chinellato, J A; Chudoba, J; Cilmo, M; Clay, R W; Cocciolo, G; Colalillo, R; Collica, L; Coluccia, M R; Conceicao, R; Contreras, F; Cook, H; Cooper, M J; Coutu, S; Covault, C E; Criss, A; Cronin, J; Curutiu, A; Dallier, R; Daniel, B; Dasso, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; de Jong, S J; De La Vega, G; Junior, W J M de Mello; Neto, J R T de Mello; De Mitri, I; de Souza, V; de Vries, K D; del Peral, L; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Diaz, J C; Castro, M L Diaz; Diep, P N; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dong, P N; Dorofeev, A; Anjos, J C dos; Dova, M T; Ebr, J; Engel, R; Erdmann, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Luis, P Facal San; Falcke, H; Fang, K; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Fick, B; Figueira, J M; Filevich, A; Filipcic, A; Foerster, N; Fox, B D; Fracchiolla, C E; Fraenkel, E D; Fratu, O; Frohlich, U; Fuchs, B; Gaior, R; Gamarra, R F; Gambetta, S; Garcia, B; Roca, S T Garcia; Garcia-Gamez, D; Garcia-Pinto, D; Garilli, G; Bravo, A Gascon; Gemmeke, H; Ghia, P L; Giller, M; Gitto, J; Glaser, C; Glass, H; Albarracin, F Gomez; Berisso, M Gomez; Vitale, P F Gomez; Goncalves, P; Gonzalez, J G; Gookin, B; Gorgi, A; Gorham, P; Gouffon, P; Grebe, S; Griffith, N; Grillo, A F; Grubb, T D; Guardincerri, Y; Guarino, F; Guedes, G P; Hansen, P; Harari, D; Harrison, T A; Harton, J L; Haungs, A; Hebbeker, T; Heck, D; Herve, A E; Hill, G C; Hojvat, C; Hollon, N; Homola, P; Hoerandel, J R; Horvath, P; Hrabovsky, M; Huber, D; Huege, T; Insolia, A; Isar, P G; Jansen, S; Jarne, C; Josebachuili, M; Kadija, K; Kambeitz, O; Kampert, K H; Karhan, P; Kasper, P; Katkov, I; Kegl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Knapp, J; Krause, R; Krohm, N; Kroemer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; La Rosa, G; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Coz, S Le; Leao, M S A B; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; Lopez, R; Aguera, A Lopez; Louedec, K; Bahilo, J Lozano; Lu, L; Lucero, A; Ludwig, M; Lyberis, H; Maccarone, M C; Macolino, C; Malacari, M; Maldera, S; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Maris, I C; Falcon, H R Marquez; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martinez; Martraire, D; Meza, J J Masias; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, G; Maurel, D; Maurizio, D; Mayotte, E; Mazur, P O; Medina, C; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Messina, S; Meyhandan, R; Micanovic, S; Micheletti, M I; Middendorf, L; Minaya, I A; Miramonti, L; Mitrica, B; Molina-Bueno, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morales, B; Morello, C; Moreno, J C; Mostafa, M; Moura, C A; Muller, M A; Muller, G; Munchmeyer, M; Mussa, R; Navarra, G; Navarro, J L; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Nhung, P T; Niechciol, M; Niemietz, L; Niggemann, T; Nitz, D; Nosek, D; Novzka, L; Oehlschlager, J; Olinto, A; Oliveira, M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Parente, G; Parra, A; Pastor, S; Paul, T; Pech, M; Pekala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Petrera, S; Petrolini, A; Petrov, Y; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Plum, M; Pontz, M; Porcelli, A; Preda, T; Privitera, P; Prouza, M; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rivera, H; Rizi, V; Roberts, J; de Carvalho, W Rodrigues; Cabo, I Rodriguez; Fernandez, G Rodriguez; Martino, J Rodriguez; Rojo, J Rodriguez; Rodriguez-Frias, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Rouille-d'Orfeuil, B; Roulet, E; Rovero, A C; Ruhle, C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Greus, F Salesa; Salina, G; Sanchez, F; Sanchez-Lucas, P; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, A; Scholten, O; Schoorlemmer, H; Schovanek, P; Schroeder, F G; Schulz, A; Schulz, J; Sciutto, S J; Scuderi, M; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Sima, O; Smialkowski, A; Smida, R; Snow, G R; Sommers, P; Sorokin, J; Spinka, H; Squartini, R; Srivastava, Y N; Stanic, S; Stapleton, J; Stasielak, J; Stephan, M; Straub, M; Stutz, A; Suarez, F; Suomijarvi, T; Supanitsky, A D; Susa, T; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Tapia, A; Tartare, M; Tacscuau, O; Tcaciuc, R; Thao, N T; Tiffenberg, J; Timmermans, C; Tkaczyk, W; Peixoto, C J Todero; Toma, G; Tomankova, L; Tome, B; Tonachini, A; Elipe, G Torralba; Machado, D Torres; Travnicek, P; Tridapalli, D B; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Galicia, J F Valdes; Valino, I; Valore, L; van Aar, G; Berg, A M van den; van Velzen, S; van Vliet, A; Varela, E; Cardenas, B Vargas; Varner, G; Vazquez, J R; Vazquez, R A; Veberic, D; Verzi, V; Vicha, J; Videla, M; Villasenor, L; Wahlberg, H; Wahrlich, P; Wainberg, O; Walz, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Werner, F; Westerhoff, S; Whelan, B J; Widom, A; Wieczorek, G; Wiencke, L; Wilczynska, B; Wilczynski, H; Will, M; Williams, C; Winchen, T; Wundheiler, B; Wykes, S; Yamamoto, T; Yapici, T; Younk, P; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Zhou, J; Zhu, Y; Silva, M Zimbres; Ziolkowski, M

    2013-01-01

    Joint contributions of the Pierre Auger and Telescope Array Collaborations to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013: cross-calibration of the fluorescence telescopes, large scale anisotropies and mass composition.

  6. A likelihood method to cross-calibrate air-shower detectors

    CERN Document Server

    Dembinski, H P; Mariş, I C; Roth, M; Veberič, D

    2016-01-01

    We present a detailed statistical treatment of the energy calibration of hybrid air-shower detectors, which combine a surface detector array and a fluorescence detector, to obtain an unbiased estimate of the calibration curve. The special features of calibration data from air showers prevent unbiased results, if a standard least-squares fit is applied to the problem. We develop a general maximum-likelihood approach, based on the detailed statistical model, to solve the problem. Our approach was developed for the Pierre Auger Observatory, but the applied principles are general and can be transferred to other air-shower experiments, even to the cross-calibration of other observables. Since our general likelihood function is expensive to compute, we derive two approximations with significantly smaller computational cost. In the recent years both have been used to calibrate data of the Pierre Auger Observatory. We demonstrate that these approximations introduce negligible bias when they are applied to simulated t...

  7. Static calibration for measurement of loads in wind tunnel tests on Shuttle surface tiles

    Science.gov (United States)

    Rummler, D. R.; Pinson, L. D.

    1982-01-01

    A description is given of the procedures used for the static calibrations of the Coe (1981) sensor array to determine normal force, pitching moment, and rolling moment from the ensemble of sensor outputs. The use of independent data to confirm the validity of the calibration is also described. Two methods are used in calibrating the Coe sensors. In the first, calibration loads and readings are arranged in matrix form and are assumed to be related in a linear fashion. In the second, each Coe sensor reading is regarded as a sum of contributions from each of the calibration loads. It is shown that the Coe load sensors, in conjunction with either of two data analysis methods, can be used to determine the forces and moments experienced by a Shuttle TPS tile.

  8. LOFAR: The LOw-Frequency ARray

    Science.gov (United States)

    van Haarlem, M. P.; Wise, M. W.; Gunst, A. W.; Heald, G.; McKean, J. P.; Hessels, J. W. T.; de Bruyn, A. G.; Nijboer, R.; Swinbank, J.; Fallows, R.; Brentjens, M.; Nelles, A.; Beck, R.; Falcke, H.; Fender, R.; Hörandel, J.; Koopmans, L. V. E.; Mann, G.; Miley, G.; Röttgering, H.; Stappers, B. W.; Wijers, R. A. M. J.; Zaroubi, S.; van den Akker, M.; Alexov, A.; Anderson, J.; Anderson, K.; van Ardenne, A.; Arts, M.; Asgekar, A.; Avruch, I. M.; Batejat, F.; Bähren, L.; Bell, M. E.; Bell, M. R.; van Bemmel, I.; Bennema, P.; Bentum, M. J.; Bernardi, G.; Best, P.; Bîrzan, L.; Bonafede, A.; Boonstra, A.-J.; Braun, R.; Bregman, J.; Breitling, F.; van de Brink, R. H.; Broderick, J.; Broekema, P. C.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; van Cappellen, W.; Ciardi, B.; Coenen, T.; Conway, J.; Coolen, A.; Corstanje, A.; Damstra, S.; Davies, O.; Deller, A. T.; Dettmar, R.-J.; van Diepen, G.; Dijkstra, K.; Donker, P.; Doorduin, A.; Dromer, J.; Drost, M.; van Duin, A.; Eislöffel, J.; van Enst, J.; Ferrari, C.; Frieswijk, W.; Gankema, H.; Garrett, M. A.; de Gasperin, F.; Gerbers, M.; de Geus, E.; Grießmeier, J.-M.; Grit, T.; Gruppen, P.; Hamaker, J. P.; Hassall, T.; Hoeft, M.; Holties, H. A.; Horneffer, A.; van der Horst, A.; van Houwelingen, A.; Huijgen, A.; Iacobelli, M.; Intema, H.; Jackson, N.; Jelic, V.; de Jong, A.; Juette, E.; Kant, D.; Karastergiou, A.; Koers, A.; Kollen, H.; Kondratiev, V. I.; Kooistra, E.; Koopman, Y.; Koster, A.; Kuniyoshi, M.; Kramer, M.; Kuper, G.; Lambropoulos, P.; Law, C.; van Leeuwen, J.; Lemaitre, J.; Loose, M.; Maat, P.; Macario, G.; Markoff, S.; Masters, J.; McFadden, R. A.; McKay-Bukowski, D.; Meijering, H.; Meulman, H.; Mevius, M.; Middelberg, E.; Millenaar, R.; Miller-Jones, J. C. A.; Mohan, R. N.; Mol, J. D.; Morawietz, J.; Morganti, R.; Mulcahy, D. D.; Mulder, E.; Munk, H.; Nieuwenhuis, L.; van Nieuwpoort, R.; Noordam, J. E.; Norden, M.; Noutsos, A.; Offringa, A. R.; Olofsson, H.; Omar, A.; Orrú, E.; Overeem, R.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A.; Rafferty, D.; Rawlings, S.; Reich, W.; de Reijer, J.-P.; Reitsma, J.; Renting, G. A.; Riemers, P.; Rol, E.; Romein, J. W.; Roosjen, J.; Ruiter, M.; Scaife, A.; van der Schaaf, K.; Scheers, B.; Schellart, P.; Schoenmakers, A.; Schoonderbeek, G.; Serylak, M.; Shulevski, A.; Sluman, J.; Smirnov, O.; Sobey, C.; Spreeuw, H.; Steinmetz, M.; Sterks, C. G. M.; Stiepel, H.-J.; Stuurwold, K.; Tagger, M.; Tang, Y.; Tasse, C.; Thomas, I.; Thoudam, S.; Toribio, M. C.; van der Tol, B.; Usov, O.; van Veelen, M.; van der Veen, A.-J.; ter Veen, S.; Verbiest, J. P. W.; Vermeulen, R.; Vermaas, N.; Vocks, C.; Vogt, C.; de Vos, M.; van der Wal, E.; van Weeren, R.; Weggemans, H.; Weltevrede, P.; White, S.; Wijnholds, S. J.; Wilhelmsson, T.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, A.; van Zwieten, J.

    2013-08-01

    LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10-240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR's new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory.

  9. LEAP: the Large European Array for Pulsars

    Science.gov (United States)

    Bassa, C. G.; Janssen, G. H.; Karuppusamy, R.; Kramer, M.; Lee, K. J.; Liu, K.; McKee, J.; Perrodin, D.; Purver, M.; Sanidas, S.; Smits, R.; Stappers, B. W.

    2016-02-01

    The Large European Array for Pulsars (LEAP) is an experiment that harvests the collective power of Europe's largest radio telescopes in order to increase the sensitivity of high-precision pulsar timing. As part of the ongoing effort of the European Pulsar Timing Array, LEAP aims to go beyond the sensitivity threshold needed to deliver the first direct detection of gravitational waves. The five telescopes presently included in LEAP are the Effelsberg Telescope, the Lovell Telescope at Jodrell Bank, the Nançay Radio Telescope, the Sardinia Radio Telescope and the Westerbork Synthesis Radio Telescope. Dual polarization, Nyquist-sampled time series of the incoming radio waves are recorded and processed offline to form the coherent sum, resulting in a tied-array telescope with an effective aperture equivalent to a 195-m diameter circular dish. All observations are performed using a bandwidth of 128 MHz centred at a frequency of 1396 MHz. In this paper, we present the design of the LEAP experiment, the instrumentation, the storage and transfer of data and the processing hardware and software. In particular, we present the software pipeline that was designed to process the Nyquist-sampled time series, measure the phase and time delays between each individual telescope and a reference telescope and apply these delays to form the tied-array coherent addition. The pipeline includes polarization calibration and interference mitigation. We also present the first results from LEAP and demonstrate the resulting increase in sensitivity, which leads to an improvement in the pulse arrival times.

  10. Melter feed system 3-way feed valve Auma motorized operator

    International Nuclear Information System (INIS)

    This document discusses the Scale Melter currently testing feed systems. One component of that system is a valve operator, which directs the feed slurry or flush water through the 3-way ball valve to the melter. This valve operator may be causing problems on the TNX Scale Melter by failing to accurately align the feed valve ports

  11. Solar array deployment mechanism

    Science.gov (United States)

    Calassa, Mark C.; Kackley, Russell

    1995-05-01

    This paper describes a Solar Array Deployment Mechanism (SADM) used to deploy a rigid solar array panel on a commercial spacecraft. The application required a deployment mechanism design that was not only lightweight, but also could be produced and installed at the lowest possible cost. This paper covers design, test, and analysis of a mechanism that meets these requirements.

  12. Calibration of "Babyline" RP instruments

    CERN Multimedia

    2015-01-01

      If you have old RP instrumentation of the “Babyline” type, as shown in the photo, please contact the Radiation Protection Group (Joffrey Germa, 73171) to have the instrument checked and calibrated. Thank you. Radiation Protection Group

  13. Multi-Mycotoxin Screening Reveals the Occurrence of 139 Different Secondary Metabolites in Feed and Feed Ingredients

    OpenAIRE

    Rudolf Krska; Karin Naehrer; Christina Schwab; Michael Sulyok; Elisabeth Streit; Gerd Schatzmayr

    2013-01-01

    The development of liquid chromatography-mass spectrometry (LC-MS)/mass spectrometry (MS) methods for the simultaneous detection and quantification of a broad spectrum of mycotoxins has facilitated the screening of a larger number of samples for contamination with a wide array of less well-known “emerging” mycotoxins and other metabolites. In this study, 83 samples of feed and feed raw materials were analysed. All of them were found to contain seven to 69 metabolites. The total number of dete...

  14. Calibration Of A Nucleonic Density Gauge For Molasses Brie Control In Vacuum Pan Operation

    International Nuclear Information System (INIS)

    In order to establish a strict control of the molasses to be feed to the vacuum pan station during industrial evaluations of this facility in the next season, the calibration of a prototype of nucleonic density gauge, constructed in close collaboration between CEADEN and ICINAZ has been performed. Some preliminary results of this complementary task of the project are described

  15. Calibration of a nucleonic density gauge for molasses brix control in vacuum pan operation

    International Nuclear Information System (INIS)

    In order to establish a strict control of the molasses to be feed to the vacuum pan station during industrial evaluations of this facility in the next season, the calibration of a prototype of nucleonic density gauge, constructed in close collaboration between ceaden and icinaz has been performed. Some preliminary results of this complementary task of the project are described

  16. Micromachined electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat (Edgewood, NM); Wessendorf, Kurt O. (Albuquerque, NM)

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  17. Microfabricated ion trap array

    Science.gov (United States)

    Blain, Matthew G.; Fleming, James G.

    2006-12-26

    A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

  18. Pressures Detector Calibration and Measurement

    CERN Document Server

    AUTHOR|(CDS)2156315

    2016-01-01

    This is report of my first and second projects (of 3) in NA61. I did data taking and analysis in order to do calibration of pressure detectors and verified it. I analyzed the data by ROOT software using the C ++ programming language. The first part of my project was determination of calibration factor of pressure sensors. Based on that result, I examined the relation between pressure drop, gas flow rate of in paper filter and its diameter.

  19. Beam Imaging and Luminosity Calibration

    CERN Document Server

    Klute, Markus; Salfeld-Nebgen, Jakob

    2016-01-01

    We discuss a method to reconstruct two-dimensional proton bunch densities using vertex distributions accumulated during LHC beam-beam scans. The $x$-$y$ correlations in the beam shapes are studied and an alternative luminosity calibration technique is introduced. We demonstrate the method on simulated beam-beam scans and estimate the uncertainty on the luminosity calibration associated to the beam-shape reconstruction to be below 1\\%.

  20. Multiple part feeding

    DEFF Research Database (Denmark)

    Hvilshøj, Mads; Bøgh, Simon; Nielsen, Oluf Skov;

    2012-01-01

    Purpose - The purpose of this paper is to present experience from a real-world demonstration of autonomous industrial mobile manipulation (AIMM) based on the mobile manipulator "Little Helper" performing multiple part feeding at the pump manufacturer Grundfos A/S. Design/methodology/approach - Th......Purpose - The purpose of this paper is to present experience from a real-world demonstration of autonomous industrial mobile manipulation (AIMM) based on the mobile manipulator "Little Helper" performing multiple part feeding at the pump manufacturer Grundfos A/S. Design......" is capable of successfully servicing four part feeders in three production cells using command signals from an Open Process Control (OPC) server. Furthermore, the paper presents future research and development suggestions for AIMM, which contributes to near-term industrial maturation and implementation...

  1. WFC3: UVIS Dark Calibration

    Science.gov (United States)

    Bourque, Matthew; Biretta, John A.; Anderson, Jay; Baggett, Sylvia M.; Gunning, Heather C.; MacKenty, John W.

    2014-06-01

    Wide Field Camera 3 (WFC3), a fourth-generation imaging instrument on board the Hubble Space Telescope (HST), has exhibited excellent performance since its installation during Servicing Mission 4 in May 2009. The UVIS detector, comprised of two e2v CCDs, is one of two channels available on WFC3 and is named for its ultraviolet and visible light sensitivity. We present the various procedures and results of the WFC3/UVIS dark calibration, which monitors the health and stability of the UVIS detector, provides characterization of hot pixels and dark current, and produces calibration files to be used as a correction for dark current in science images. We describe the long-term growth of hot pixels and the impacts that UVIS Charge Transfer Efficiency (CTE) losses, postflashing, and proximity to the readout amplifiers have on the population. We also discuss the evolution of the median dark current, which has been slowly increasing since the start of the mission and is currently ~6 e-/hr/pix, averaged across each chip. We outline the current algorithm for creating UVIS dark calibration files, which includes aggressive cosmic ray masking, image combination, and hot pixel flagging. Calibration products are available to the user community, typically 3-5 days after initial processing, through the Calibration Database System (CDBS). Finally, we discuss various improvements to the calibration and monitoring procedures. UVIS dark monitoring will continue throughout and beyond HST’s current proposal cycle.

  2. Feeding the City

    OpenAIRE

    Roncaglia, Sara; Giorgio Solinas, Pier

    2015-01-01

    Every day in Mumbai 6,000 dabbawalas (literally translated as "those who carry boxes") distribute a staggering 200,000 home-cooked lunchboxes to the city's workers and students. Giving employment and status to thousands of largely illiterate villagers from Mumbai's hinterland, this co-operative has been in operation since the late nineteenth century. It provides one of the most efficient delivery networks in the world: only one lunch in six million goes astray. Feeding the City is an ethnogr...

  3. Feed sources for livestock

    OpenAIRE

    Zanten, van, J.H.

    2016-01-01

    Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way. Current levels of production of especially animal-source food (ASF), pose severe pressure on the environment via their emissions to air, water, and soil; and their use of scarce resources, such as la...

  4. Corrugated waveguide monopulse feed

    Science.gov (United States)

    Elliott, R. D.; Clarricoats, P. J. B.

    1980-04-01

    The excitation coefficients of modes in a circular corrugated waveguide that arise when dominant modes are incident from a cluster of four square waveguides are calculated. Monopulse-like radiation patterns arise when modes in the input guides are appropriately phased. Factors influencing the crosspolar performance of the feed are discussed, and the dependence of the excitation coefficients on waveguide and junction parameters is predicted.

  5. Residual Feed Intake

    OpenAIRE

    Sainz, Roberto D.; Paulino, Pedro V.

    2004-01-01

    Introduction Low rates of return on investment for livestock operations are a fact of life. Producers have little impact on the market price for their cattle; therefore management must be focused on the things producers can actually do something about. For many years, genetic selection programs have focused on production (output) traits, with little attention given to production costs (inputs). Recently, this view has begun to change, and the efficiency of conversion of feed (i.e., t...

  6. Optical Magnetometer Array for Fetal Magnetocardiography

    CERN Document Server

    Wyllie, Robert; Wakai, Ronald T; Walker, Thad G

    2012-01-01

    We describe an array of spin-exchange relaxation free optical magnetometers designed for detection of fetal magnetocardiography (fMCG) signals. The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. Using this array, we present the first measurements of fMCG signals using an atomic magnetometer.

  7. Clogging of feeding tubes.

    Science.gov (United States)

    Marcuard, S P; Perkins, A M

    1988-01-01

    This is a report of an in vitro study evaluating clotting ability of some formulas with intact protein and hydrolyzed protein sources in a series of buffers ranging from a pH of 1 thru 10. The following 10 products were tested: Ensure Plus, Ensure, Enrich, Osmolite, Pulmocare, Citrotein, Resource, Vivonex TEN, Vital, and Hepatic Acid II. Protein (10 and 20 g/liter) was added to Citrotein and Ensure Plus. All formulas were tested at full and some at half strength. Clotting occurred only in premixed intact protein formulas (Pulmocare, Ensure Plus, Osmolite, Enrich, Ensure) and in Resource. No clotting was observed for Citrotein (intact protein formula in powder form), Vital, Vivonex TEN, and Hepatic Aid II. Adding protein did not cause or increase clotting. In summary, clotting of some liquid formula diet appears to be an important factor causing possible gastric feeding tube occlusion. The following measures may help in preventing this problem: flushing before and after aspirating for gastric residuals to eliminate acid precipitation of formula in the feeding tube, advance the nasogastric feeding tube into the duodenum if possible, and avoid mixing these products with liquid medications having a pH value of 5.0 or less. PMID:3138452

  8. Design of a Compact Wideband Antenna Array for Microwave Imaging Applications

    Directory of Open Access Journals (Sweden)

    J. Puskely

    2013-12-01

    Full Text Available In the paper, wideband antenna arrays aimed at microwave imaging applications and SAR applications operating at Ka band were designed. The antenna array feeding network is realized by a low-loss SIW technology. Moreover, we have replaced the large feed network comprised of various T and Y junctions by a simple broadband network of compact size to more reduce losses in the substrate integrated waveguide and also save space on the PCB. The designed power 8-way divider is complemented by a wideband substrate integrated waveguide to a grounded coplanar waveguide transition and directly connected to the antenna elements. The measured results of antenna array are consistent with our simulation. Obtained results of the developed array demonstrated improvement compared to previously developed binary feed networks with microstrip or SIW splitters.

  9. Coupling between crossed dipole feeds

    DEFF Research Database (Denmark)

    Andersen, J.; Schjær-Jacobsen, Hans; Lessow, H.

    1974-01-01

    as a function of orientation and feeding network properties. The antennas are used as feeds for a parabolic reflector, and the effect of coupling on the secondary fields is analyzed. Especially significant is the polarization loss and it may, to some extent, be reduced by a proper choice of feeding network....

  10. Food Safety Information RSS feed

    Data.gov (United States)

    U.S. Department of Health & Human Services — This is an RSS Feed of Food Safety information that’s produced in real-time by the CDC. This RSS feed is the integration of two other XML feeds, one from the USDA's...

  11. Understanding Instrumental Stokes Leakage in Murchison Widefield Array Polarimetry

    CERN Document Server

    Sutinjo, Adrian; Lenc, Emil; Wayth, Randall B; Padhi, Shantanu; Hall, Peter; Tingay, Steven J

    2014-01-01

    This paper offers an electromagnetic, more specifically array theory, perspective on understanding strong instrumental polarization effects for planar low-frequency "aperture arrays" with the Murchison Widefield Array (MWA) as an example. A long-standing issue that has been seen here is significant instrumental Stokes leakage after calibration, particularly in Stokes Q at high frequencies. A simple model that accounts for inter-element mutual coupling is presented which explains the prominence of Q leakage seen when the array is scanned away from zenith in the principal planes. On these planes, the model predicts current imbalance in the X (E-W) and Y (N-S) dipoles and hence the Q leakage. Although helpful in concept, we find that this model is inadequate to explain the full details of the observation data. This finding motivates further experimentation with more rigorous models that account for both mutual coupling and embedded element patterns. Two more rigorous models are discussed: the "full" and "average...

  12. Integrated Seismic Event Detection and Location by Advanced Array Processing

    Energy Technology Data Exchange (ETDEWEB)

    Kvaerna, T; Gibbons, S J; Ringdal, F; Harris, D B

    2007-02-09

    The principal objective of this two-year study is to develop and test a new advanced, automatic approach to seismic detection/location using array processing. We address a strategy to obtain significantly improved precision in the location of low-magnitude events compared with current fully-automatic approaches, combined with a low false alarm rate. We have developed and evaluated a prototype automatic system which uses as a basis regional array processing with fixed, carefully calibrated, site-specific parameters in conjuction with improved automatic phase onset time estimation. We have in parallel developed tools for Matched Field Processing for optimized detection and source-region identification of seismic signals. This narrow-band procedure aims to mitigate some of the causes of difficulty encountered using the standard array processing system, specifically complicated source-time histories of seismic events and shortcomings in the plane-wave approximation for seismic phase arrivals at regional arrays.

  13. An Ultrawideband Monopole Fractal Antenna with Coplanar Waveguide Feed

    OpenAIRE

    Muhammad Naeem Iqbal; Hamood-Ur-Rahman; Syeda Fizzah Jilani

    2014-01-01

    A novel ultrawideband fractal antenna in monopole configuration is proposed. Wideband behavior and miniaturization is achieved using concentric heptagonal array structure. Coplanar waveguide is used to feed fractal antenna. Base shape for fractal antenna is heptagonal geometry. Final fractal shape is achieved by performing four base shape iterations. FR4 substrate is used for antenna fabrication. Simulated and measured results comparison shows a bandwidth of 7 GHz with 9 GHz center frequency....

  14. Breadboard linear array scan imager using LSI solid-state technology

    Science.gov (United States)

    Tracy, R. A.; Brennan, J. A.; Frankel, D. G.; Noll, R. E.

    1976-01-01

    The performance of large scale integration photodiode arrays in a linear array scan (pushbroom) breadboard was evaluated for application to multispectral remote sensing of the earth's resources. The technical approach, implementation, and test results of the program are described. Several self scanned linear array visible photodetector focal plane arrays were fabricated and evaluated in an optical bench configuration. A 1728-detector array operating in four bands (0.5 - 1.1 micrometer) was evaluated for noise, spectral response, dynamic range, crosstalk, MTF, noise equivalent irradiance, linearity, and image quality. Other results include image artifact data, temporal characteristics, radiometric accuracy, calibration experience, chip alignment, and array fabrication experience. Special studies and experimentation were included in long array fabrication and real-time image processing for low-cost ground stations, including the use of computer image processing. High quality images were produced and all objectives of the program were attained.

  15. An investigation into force-moment calibration techniques applicable to a magnetic suspension and balance system. M.S. Thesis

    Science.gov (United States)

    Eskins, Jonathan

    1988-01-01

    The problem of determining the forces and moments acting on a wind tunnel model suspended in a Magnetic Suspension and Balance System is addressed. Two calibration methods were investigated for three types of model cores, i.e., Alnico, Samarium-Cobalt, and a superconducting solenoid. Both methods involve calibrating the currents in the electromagnetic array against known forces and moments. The first is a static calibration method using calibration weights and a system of pulleys. The other method, dynamic calibration, involves oscillating the model and using its inertia to provide calibration forces and moments. Static calibration data, found to produce the most reliable results, is presented for three degrees of freedom at 0, 15, and -10 deg angle of attack. Theoretical calculations are hampered by the inability to represent iron-cored electromagnets. Dynamic calibrations, despite being quicker and easier to perform, are not as accurate as static calibrations. Data for dynamic calibrations at 0 and 15 deg is compared with the relevant static data acquired. Distortion of oscillation traces is cited as a major source of error in dynamic calibrations.

  16. Introduction to adaptive arrays

    CERN Document Server

    Monzingo, Bob; Haupt, Randy

    2011-01-01

    This second edition is an extensive modernization of the bestselling introduction to the subject of adaptive array sensor systems. With the number of applications of adaptive array sensor systems growing each year, this look at the principles and fundamental techniques that are critical to these systems is more important than ever before. Introduction to Adaptive Arrays, 2nd Edition is organized as a tutorial, taking the reader by the hand and leading them through the maze of jargon that often surrounds this highly technical subject. It is easy to read and easy to follow as fundamental concept

  17. Timing calibration and spectral cleaning of LOFAR time series data

    CERN Document Server

    Corstanje, A; Enriquez, J E; Falcke, H; Hörandel, J R; Krause, M; Nelles, A; Rachen, J P; Schellart, P; Scholten, O; ter Veen, S; Thoudam, S; Trinh, T N G

    2016-01-01

    We describe a method for spectral cleaning and timing calibration of short voltage time series data from individual radio interferometer receivers. It makes use of the phase differences in Fast Fourier Transform (FFT) spectra across antenna pairs. For strong, localized terrestrial sources these are stable over time, while being approximately uniform-random for a sum over many sources or for noise. Using only milliseconds-long datasets, the method finds the strongest interfering transmitters, a first-order solution for relative timing calibrations, and faulty data channels. No knowledge of gain response or quiescent noise levels of the receivers is required. With relatively small data volumes, this approach is suitable for use in an online system monitoring setup for interferometric arrays. We have applied the method to our cosmic-ray data collection, a collection of measurements of short pulses from extensive air showers, recorded by the LOFAR radio telescope. Per air shower, we have collected 2 ms of raw tim...

  18. Compound simulator IR radiation characteristics test and calibration

    Science.gov (United States)

    Li, Yanhong; Zhang, Li; Li, Fan; Tian, Yi; Yang, Yang; Li, Zhuo; Shi, Rui

    2015-10-01

    The Hardware-in-the-loop simulation can establish the target/interference physical radiation and interception of product flight process in the testing room. In particular, the simulation of environment is more difficult for high radiation energy and complicated interference model. Here the development in IR scene generation produced by a fiber array imaging transducer with circumferential lamp spot sources is introduced. The IR simulation capability includes effective simulation of aircraft signatures and point-source IR countermeasures. Two point-sources as interference can move in two-dimension random directions. For simulation the process of interference release, the radiation and motion characteristic is tested. Through the zero calibration for optical axis of simulator, the radiation can be well projected to the product detector. The test and calibration results show the new type compound simulator can be used in the hardware-in-the-loop simulation trial.

  19. NuSTAR on-ground calibration I: Imaging quality

    DEFF Research Database (Denmark)

    Westergaard, Niels Jørgen Stenfeldt; Madsen, Kristin K.; Brejnholt, Nicolai;

    2012-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) launched in June 2012 carries the first focusing hard Xray (5 - 80 keV) telescope to orbit. The on-ground calibration was performed at the RaMCaF facility at Nevis, Columbia University. During the assembly of the telescopes, mechanical surface me...... the imaging properties for X-ray sources at infinite distance. © 2012 SPIE....... metrology provided surface maps of the reflecting surfaces. Several flight coated mirrors were brought to BNL for scattering measurements. The information from both sources is fed to a raytracing code that is tested against the on-ground calibration data. The code is subsequently used for predicting...

  20. Synthesis of Antenna Arrays and Parasitic Antenna Arrays with Mutual Couplings

    Directory of Open Access Journals (Sweden)

    M. Thevenot

    2012-01-01

    Full Text Available A synthesis method to design multielement antennas with couplings is presented. The main objective is to perform a rigorous determination of the electromagnetic characteristics involved in the design, especially with arrays of moderate sizes. The aim is to conceive jointly and efficiently the antenna and the circuits to connect (feed distribution network, power amplifiers, reactive loads, etc.. The subsequent objective is to improve the understanding and capabilities of strongly coupled antennas. As a whole, the synthesis procedure is then applied to different antenna architectures in order to show its efficiency and versatility. A focus on some antenna concepts where the management of couplings is a key factor to improve the performances is presented. After describing the synthesis procedure, the first category of coupled multielement antenna studied concerns radiating arrays in linear or circular polarization. A design including couplings effects on an active array is also presented. Then, the method is applied to parasitic antenna arrays and a specific investigation on reflectarray antenna is performed as they can be considered as a particular case of parasitic arrays.

  1. P systems with array objects and array rewriting rules

    Institute of Scientific and Technical Information of China (English)

    K.G. Subramanian; R. Saravanan; M. Geethalakshmi; P. Helen Chandra; M. Margenstern

    2007-01-01

    Array P systems were introduced by Pǎun Gh. which is linking the two areas of membrane computing and picture grammars. Puzzle grammars were introduced by us for generating connected picture arrays in the two-dimensional plane, motivated by the problem of tiling the plane. On the other hand, incorporating into arrays the developmental type of generation used in the well-known biologically motivated L systems, Siromoney and Siromoney proposed a very general rectangular array generating model, called extended controlled tabled L array system (ECTLAS). In this paper we introduce two variations of the array P system, called BPG array P system and parallel array P system. The former has in the regions array objects and basic puzzle grammar rules (BPG), which are a specific kind of puzzle grammar rules. In the latter, the regions have rectangular array objects and tables of context-free rules. We examine these two types of P systems for their array generative power.

  2. Enteral feeding without pancreatic stimulation

    DEFF Research Database (Denmark)

    Kaushik, Neeraj; Pietraszewski, Marie; Holst, Jens Juul;

    2005-01-01

    OBJECTIVE: All forms of commonly practiced enteral feeding techniques stimulate pancreatic secretion, and only intravenous feeding avoids it. In this study, we explored the possibility of more distal enteral infusions of tube feeds to see whether activation of the ileal brake mechanism can result...... in enteral feeding without pancreatic stimulation, with particular reference to trypsin, because the avoidance of trypsin stimulation may optimize enteral feeding in acute pancreatitis. METHODS: The pancreatic secretory responses to feeding were studied in 36 healthy volunteers by standard double...... in plasma glucagon-like peptide-1 and peptide YY concentrations. CONCLUSIONS: Our results suggest that enteral feeding can be given without stimulating pancreatic trypsin secretion provided it is delivered into the mid-distal jejunum. The mechanism may involve activation of the ileal brake mechanism....

  3. Radiation pasteurization of poultry feed: Preliminary results of feeding tests

    International Nuclear Information System (INIS)

    Feed used to rear farm animals for human consumption has often been implicated as a vehicle for dissemination of microbial pathogens that can adversely affect both animals or birds, and humans. Radiation pasteurization of animal feed to improve its microbiological quality should reduce the incidence of feed-borne infection in the herd or flock. This would result in safer food for the consumer, and improved economic performance of the production unit. This latter benefit is particularly important because it would directly offset the cost of treating the feed. The likelihood of occurrence, as well as the magnitude, of any improved economic performance in the herd or flock consuming the irradiated feed must be determined experimentally. Accordingly, short term feeding tests were carried out to determine the effect of radiation pasteurization of poultry feed on growth performance of young chicks. The results suggest that radiation pasteurization of poultry feed may have a beneficial effect on the feed conversion efficiency of the birds consuming that feed. 10 refs, 8 tabs

  4. The KLOE Online Calibration System

    Institute of Scientific and Technical Information of China (English)

    E.Pasqualucci

    2001-01-01

    Based on all the features of the KLOE online software,the online calibration system performs current calibration quality checking in real time and starts automatically new calibration procedures when needed.Acalibration manager process controls the system,implementing the interface to the online system,receiving information from the run control and translating its state transitions to a separate state machine.It acts as a " calibration run controller"and performs failure recovery when requested by a set of process checkers.The core of the system is a multi-threaded OO histogram server that receives histogramming commands by remote processes and operates on local ROOT histograms.A client library and C,fortran and C++ application interface libraries allow the user to connect and define his own histogram or read histograms owned by others using an bool-like interface.Several calibration processes running in parallel in a destributed,multiplatform environment can fill the same histograms,allowing fast external information check.A monitor thread allow remote browsing for visual inspection,Pre-filtered data are read in nonprivileged spy mode from the data acquisition system via the Kloe Integrated Dataflow,privileged spy mode from the data acquisiton system via the Kole Integrated Dataflow.The main characteristics of the system are presented.

  5. Phased-array sources based on nonlinear metamaterial nanocavities.

    Science.gov (United States)

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P; Liu, Sheng; Luk, Ting S; Kadlec, Emil A; Shaner, Eric A; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  6. A self-sufficient method for calibration of Varian electronic portal imaging device

    Science.gov (United States)

    Sun, Baozhou; Yaddanapudi, Sridhar; Goddu, Sreekrishna M.; Mutic, Sasa

    2015-01-01

    Electronic portal imaging device (EPID) is currently used for dosimetric verification of IMRT fields and linac quality assurance (QA). It is critical to understand the dosimetric response and perform an accurate and robust calibration of EPID. We present the implementation of an efficient method for the calibration and the validation of a Varian EPID, which relies only on data collected with that specific device. The calibration method is based on images obtained with five shifts of EPID panel. With this method, the relative gain (sensitivity) of each element of a detector matrix is calculated and applied on top of the calibration determined with the flood-field procedure. The calibration procedure was verified using a physical wedge inserted in the beam line and the corrected profile shows consistent results with the measurements using a calibrated 2D array. This method does not rely on the beam profile used in the flood-field calibration process, which allows EPID calibration in 10 minutes with no additional equipment compared to at least 2 hours to obtain beam profile and scanning beam equipment requirement with the conventional method.

  7. A self-sufficient method for calibration of Varian electronic portal imaging device

    International Nuclear Information System (INIS)

    Electronic portal imaging device (EPID) is currently used for dosimetric verification of IMRT fields and linac quality assurance (QA). It is critical to understand the dosimetric response and perform an accurate and robust calibration of EPID. We present the implementation of an efficient method for the calibration and the validation of a Varian EPID, which relies only on data collected with that specific device. The calibration method is based on images obtained with five shifts of EPID panel. With this method, the relative gain (sensitivity) of each element of a detector matrix is calculated and applied on top of the calibration determined with the flood-field procedure. The calibration procedure was verified using a physical wedge inserted in the beam line and the corrected profile shows consistent results with the measurements using a calibrated 2D array. This method does not rely on the beam profile used in the flood-field calibration process, which allows EPID calibration in 10 minutes with no additional equipment compared to at least 2 hours to obtain beam profile and scanning beam equipment requirement with the conventional method

  8. Flexible retinal electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat (Albuquerque, NM); Wessendorf, Kurt O. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  9. Expandable LED array interconnect

    Science.gov (United States)

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  10. Protein Functionalized Nanodiamond Arrays

    Directory of Open Access Journals (Sweden)

    Liu YL

    2010-01-01

    Full Text Available Abstract Various nanoscale elements are currently being explored for bio-applications, such as in bio-images, bio-detection, and bio-sensors. Among them, nanodiamonds possess remarkable features such as low bio-cytotoxicity, good optical property in fluorescent and Raman spectra, and good photostability for bio-applications. In this work, we devise techniques to position functionalized nanodiamonds on self-assembled monolayer (SAMs arrays adsorbed on silicon and ITO substrates surface using electron beam lithography techniques. The nanodiamond arrays were functionalized with lysozyme to target a certain biomolecule or protein specifically. The optical properties of the nanodiamond-protein complex arrays were characterized by a high throughput confocal microscope. The synthesized nanodiamond-lysozyme complex arrays were found to still retain their functionality in interacting with E. coli.

  11. Calibration and survey of AMANDA with the SPASE detectors

    CERN Document Server

    Ahrens, J; Barwick, S W; Bay, R C; Becka, T; Becker, K H; Bernardini, E; Bertrand, E; Binon, F; Biron, A; Boser, S; Botner, O; Bouchta, A; Bouhali, O; Burgess, T; Carius, S; Castermans, T; Chirkin, D; Conrad, J; Cooley, J; Cowen, D F; Davour, A; De Clercq, C; De Young, T R; Desiati, P; Dewulf, J P; Dickinson, E; Doksus, P; Ekstrom, P; Engel, R; Evenson, P; Feser, T; Gaisser, T K; Ganugapati, R; Gaug, M; Geenen, H; Gerhardt, L; Goldschmidt, A; Hallgren, A; Halzen, F; Hanson, K; Hardtke, R; Hauschildt, T; Hellwig, M; Herquet, P; Hill, G C; Hinton, J A; Hughey, B; Hulth, P O; Hultqvist, K; Hundertmark, S; Jacobsen, J; Karle, A; Kim, J; Köpke, L; Kowalski, M; Kühn, K; Lamoureux, J I; Leich, H; Leuthold, M; Lindahl, P; Liubarsky, I; Lloyd Evans, J; Madsen, J; Mandli, K; Marciniewski, P; Martello, D; Matis, H S; McParland, C P; Messarius, T; Miller, T C; Minaeva, Y; Miocinovic, P; Mock, P C; Morse, R; Neunhoffer, T; Niessen, P; Nygren, D R; Ogelman, H; Olbrechts, P; Perez de los Heros, C; Pohl, A C; Porrata, R; Price, P B; Przybylski, G T; Rawlins, K; Resconi, E; Rhode, W; Ribordy, M; Richter, S; Rochester, K; Rodríguez-Martino, J; Romenesko, P; Ross, D; Sander, H G; Schinarakis, K; Schlenstedt, S; Schmidt, T; Schneider, D; Schwarz, R; Silvestri, A; Solarz, M; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Steele, D; Steffen, P; Stokstad, R G; Sulanke, K H; Taboada, I; Tilav, S; Wagner, W; Walck, C; Wang, Y R; Watson, A A; Weinheimer, C; Wiebusch, C; Wiedemann, C; Wischnewski, R; Wissing, H; Woschnagg, K; Wu, W; Yodh, G; Young, S; 10.1016/j.nima.2003.12.007

    2004-01-01

    We report on the analysis of air showers observed in coincidence by the Antarctic Muon and Neutrino detector array (AMANDA-B10) and the South Pole Air Shower Experiment (SPASE-1 and SPASE-2). We discuss the use of coincident events for calibration and survey of the deep AMANDA detector as well as the response of AMANDA to muon bundles. This analysis uses data taken during 1997 when both SPASE-1 and SPASE-2 were in operation to provide a stereo view of AMANDA.

  12. The Rainwater Memorial Calibration Facility for X-Ray Optics

    DEFF Research Database (Denmark)

    Brejnholt, Nicolai; Christensen, Finn Erland; Hailey, Charles J.;

    2011-01-01

    The Nuclear Spectroscopic Telescope ARray (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5–80 keV) telescope to orbit. The ground calibration of the optics posed a challenge as the need to suppress finite source distance effects over the full optic...... beamline sports a 48 cm diameter 5–100 keV X-ray beam and is capable of carrying out detailed studies of large diameter optic elements, such as the NuSTAR optics, as well as flat multilayer-coated Silicon wafers....

  13. Calibration and Measurement Uncertainty Estimation of Radiometric Data: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Habte, A.; Sengupta, M.; Reda, I.; Andreas, A.; Konings, J.

    2014-11-01

    Evaluating the performance of photovoltaic cells, modules, and arrays that form large solar deployments relies on accurate measurements of the available solar resource. Therefore, determining the accuracy of these solar radiation measurements provides a better understanding of investment risks. This paper provides guidelines and recommended procedures for estimating the uncertainty in calibrations and measurements by radiometers using methods that follow the International Bureau of Weights and Measures Guide to the Expression of Uncertainty (GUM). Standardized analysis based on these procedures ensures that the uncertainty quoted is well documented.

  14. NuSTAR on-ground calibration II: Effective area

    OpenAIRE

    Brejnholt, Nicolai; Christensen, Finn Erland; Westergaard, Niels Jørgen Stenfeldt; Hailey, Charles J,; Koglin, Jason E.; Craig, William W.

    2012-01-01

    The Nuclear Spectroscopic Telescope ARray (NuSTAR) was launched in June 2012 carrying the first focusing hard X-ray (5−80keV) optics to orbit. The multilayer coating was carried out at the Technical University of Denmark (DTU Space). In this article we introduce the NuSTAR multilayer reference database and its implementation in the NuSTAR optic response model. The database and its implementation is validated using on-ground effectivearea calibration data and used to estimate in-orbit performa...

  15. NuSTAR on-ground calibration II: Effective area

    DEFF Research Database (Denmark)

    Brejnholt, Nicolai; Christensen, Finn Erland; Westergaard, Niels Jørgen Stenfeldt;

    2012-01-01

    The Nuclear Spectroscopic Telescope ARray (NuSTAR) was launched in June 2012 carrying the first focusing hard X-ray (5−80keV) optics to orbit. The multilayer coating was carried out at the Technical University of Denmark (DTU Space). In this article we introduce the NuSTAR multilayer reference...... database and its implementation in the NuSTAR optic response model. The database and its implementation is validated using on-ground effective area calibration data and used to estimate in-orbit performance....

  16. Calibration of a multichannel MEG system based on the signal space separation method.

    Science.gov (United States)

    Chella, F; Zappasodi, F; Marzetti, L; Della Penna, S; Pizzella, V

    2012-08-01

    For an efficient use of multichannel MEG systems, an accurate sensor calibration is extremely important. This includes the knowledge of both channel sensitivities and channel arrangement, which can deviate from original system plans, e.g., because of thermal stresses. In this paper, we propose a new solution to the calibration of a multichannel MEG sensor array based on the signal space separation (SSS) method. It has been shown that an inaccurate knowledge of sensor calibration limits the performances of the SSS method, resulting in a mismatch between the measured neuromagnetic field and its SSS reconstruction. Given a set of known magnetic sources, we show that an objective function, which strongly depends on sensor geometry, can be derived from the principal angle between the measured vector signal and the SSS basis. Hence, the MEG sensor array calibration is carried out by minimizing the objective function through a standard large-scale optimization technique. Details on the magnetic sources and calibration process are presented here. Finally, an application to the calibration of the 153-channel whole-head MEG system installed at the University of Chieti is discussed. PMID:22797687

  17. A New Dual Polarized Aperture-Coupled Printed Array for SAR Applications

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents a new design of dual polarized aperture-coupled printed antenna array. The finite-difference time-domain (FDTD) analysis of an aperture-coupled microstrip element is performed, and the effects of antenna parameters on its characteristics are obtained to guide the design of the printed array. Then an 8 × 2 dual polarized array design in X-band is introduced with configuration plots. In order to improve its isolation and cross polarization, an outphase-displacement feeding technique is adopted in the feed network. Also, the round bends are used instead of conventional right-angle bends so as to achieve better VSWR performance.Experimental results are presented, indicating the validity of the design. This dual polarized array can be applied as a sub-array of spaceborne SAR systems.

  18. Re-feeding syndrome.

    Science.gov (United States)

    Shadaba, A; Paine, J; Adlard, R; Dilkes, M

    2001-09-01

    The effect of a therapeutically administered high calorie diet in a severely malnourished patient is discussed in this case report. In patients with advanced head and neck cancer prolonged periods of malnutrition prior to admission are frequently encountered. This case report highlights the need to constantly monitor the electrolyte and vitamin levels during the early stages of instituting enteral or parenteral nutrition. By vigilant monitoring and a high index of suspicion re-feeding syndrome or severe hypophosphataemia and its associated complications can be avoided.

  19. Power calibrations for TRIGA reactors

    International Nuclear Information System (INIS)

    The purpose of this paper is to establish a framework for the calorimetric power calibration of TRIGA reactors so that reliable results can be obtained with a precision better than ± 5%. Careful application of the same procedures has produced power calibration results that have been reproducible to ± 1.5%. The procedures are equally applicable to the Mark I, Mark II and Mark III reactors as well as to reactors having much larger reactor tanks and to TRIGA reactors capable of forced cooling up to 3 MW in some cases and 15 MW in another case. In the case of forced cooled TRIGA reactors, the calorimetric power calibration is applicable in the natural convection mode for these reactors using exactly the same procedures as are discussed below for the smaller TRIGA reactors (< 2 MW)

  20. Facility for dosimetric instrument calibration

    International Nuclear Information System (INIS)

    A structure is designed consisting of a rotary support of containers with radiation sources and of a rotary plug mounted above the sources. A support post with a slide rest and arms rotating around the post longitudinal axis is mounted in the centre of the container support. THe arms support instruments to be calibrated. The colimation cone of the respective source is directed to the tensor of the instrument being calibrated. The slide rest is balanced using a counterpoise mounted in the support post. Sources are not removed from the containers in source change during measurement. The support can hold more containers and the slide rest can support more instruments to be calibrated than the existing configurations. (M.D.). 2 figs

  1. Oxytocin, feeding and satiety

    Directory of Open Access Journals (Sweden)

    Nancy eSabatier

    2013-03-01

    Full Text Available Oxytocin neurones have a physiological role in food intake and energy balance. Central administration of oxytocin is powerfully anorexigenic, reducing food intake and meal duration. The central mechanisms underlying this effect of oxytocin have become better understood in the past few years. Parvocellular neurones of the paraventricular nucleus project to the caudal brainstem to regulate feeding via autonomic functions including the gastrointestinal vago-vagal reflex. In contrast, magnocellular neurones of the supraoptic and paraventricular nuclei release oxytocin from their dendrites to diffuse to distant hypothalamic targets involved in satiety.The ventromedial hypothalamus, for example, expresses a high density of oxytocin receptors but does not contain detectable oxytocin nerve fibres. Magnocellular neurones represent targets for the anorexigenic neuropeptide α-melanocyte stimulating hormone. . In addition to homeostatic control, oxytocin may also have a role in reward-related feeding. Evidence suggests that oxytocin can selectively suppress sugar intake and that it may have a role in limiting the intake of palatable food by inhibiting the reward pathway.

  2. Advanced Liquid Feed Experiment

    Science.gov (United States)

    Distefano, E.; Noll, C.

    1993-06-01

    The Advanced Liquid Feed Experiment (ALFE) is a Hitchhiker experiment flown on board the Shuttle of STS-39 as part of the Space Test Payload-1 (STP-1). The purpose of ALFE is to evaluate new propellant management components and operations under the low gravity flight environment of the Space Shuttle for eventual use in an advanced spacecraft feed system. These components and operations include an electronic pressure regulator, an ultrasonic flowmeter, an ultrasonic point sensor gage, and on-orbit refill of an auxiliary propellant tank. The tests are performed with two transparent tanks with dyed Freon 113, observed by a camera and controlled by ground commands and an on-board computer. Results show that the electronic pressure regulator provides smooth pressure ramp-up, sustained pressure control, and the flexibility to change pressure settings in flight. The ultrasonic flowmeter accurately measures flow and detects gas ingestion. The ultrasonic point sensors function well in space, but not as a gage during sustained low-gravity conditions, as they, like other point gages, are subject to the uncertainties of propellant geometry in a given tank. Propellant transfer operations can be performed with liquid-free ullage equalization at a 20 percent fill level, gas-free liquid transfer from 20-65 percent fill level, minimal slosh, and can be automated.

  3. NASA's Metrology and Calibration program

    Science.gov (United States)

    Kern, Frederick A.

    1991-01-01

    The success of the National Aeronautics and Space Administration's scientific and engineering projects is often based on the capability and quality of the metrology and calibration programs of its field centers and facilities. A Metrology and Calibration Working Group, having representation from each of the NASA field centers and facilities, was established to develop and implement a program to provide a centralized direction and agency wide focus. A brief history of the Group is presented. The development of the Group's operating philosophy, the long term objectives, the measurement research and development program, and review of accomplishments is discussed.

  4. GREAT/SOFIA atmospheric calibration

    CERN Document Server

    Guan, Xin; Graf, Urs U; Güsten, Rolf; Okada, Yoko; Torres, Miguel Angel Requena; Simon, Robert; Wiesemeyer, Helmut

    2012-01-01

    The GREAT observations need frequency-selective calibration across the passband for the residual atmospheric opacity at flight altitude. At these altitudes the atmospheric opacity has both narrow and broad spectral features. To determine the atmospheric transmission at high spectral resolution, GREAT compares the observed atmospheric emission with atmospheric model predictions, and therefore depends on the validity of the atmospheric models. We discusse the problems identified in this comparison with respect to the observed data and the models, and describe the strategy used to calibrate the science data from GREAT/SOFIA during the first observing periods.

  5. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Kristensen, L.; Jensen, G.; Hansen, A.;

    2001-01-01

    . It is concluded that the method has the advantage that many anemometers can be calibrated accurately with a minimum of work and cost. The obvious disadvantage is that the calibration of a set of anemometersmay take more than one month in order to have wind speeds covering a sufficiently large magnitude range...... in a wind direction sector where we can be sure that the instruments are exposed to identical, simultaneous wind flows. Another main conclusion is thatstatistical uncertainty must be carefully evaluated since the individual 10 minute wind-speed averages are not statistically independent....

  6. Performance standard for dose Calibrator

    CERN Document Server

    Darmawati, S

    2002-01-01

    Dose calibrator is an instrument used in hospitals to determine the activity of radionuclide for nuclear medicine purposes. International Electrotechnical Commission (IEC) has published IEC 1303:1994 standard that can be used as guidance to test the performance of the instrument. This paper briefly describes content of the document,as well as explains the assessment that had been carried out to test the instrument accuracy in Indonesia through intercomparison measurement.Its is suggested that hospitals acquire a medical physicist to perform the test for its dose calibrator. The need for performance standard in the form of Indonesia Standard is also touched.

  7. Tank calibration; Arqueacao de tanques

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Ana [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    This work relates the analysis of the norms ISO (International Organization for Standardization) for calibration of vertical cylindrical tanks used in fiscal measurement, established on Joint Regulation no 1 of June 19, 2000 between the ANP (National Agency of Petroleum) and the INMETRO (National Institute of Metrology, Normalization and Industrial Quality). In this work a comparison between norms ISO and norms published by the API (American Petroleum Institute) and the IP (Institute of Petroleum) up to 2001 was made. It was concluded that norms ISO are wider than norms API, IP, and INMETRO methods in the calibration of vertical cylindrical tanks. (author)

  8. Rapid Evaluation of Power Degradation in Series Connection of Single Feeding Microsized Microbial Fuel Cells

    KAUST Repository

    Rojas, Jhonathan Prieto

    2014-07-08

    We have developed a sustainable, single feeding, microsized, air-cathode and membrane-free microbial fuel cells with a volume of 40 mu L each, which we have used for rapid evaluation of power generation and viability of a series array of three cells seeking higher voltage levels. Contrary to expectations, the achieved power density was modest (45 mWm(-3)), limited due to non-uniformities in assembly and the single-channel feeding system.

  9. A Microfabricated 8-40 GHz Dual-Polarized Reflector Feed

    Science.gov (United States)

    Vanhille, Kenneth; Durham, Tim; Stacy, William; Karasiewicz, David; Caba, Aaron; Trent, Christopher; Lambert, Kevin; Miranda, Felix

    2014-01-01

    Planar antennas based on tightly coupled dipole arrays (also known as a current sheet antenna or CSA) are amenable for use as electronically scanned phased arrays. They are capable of performance nearing a decade of bandwidth. These antennas have been demonstrated in many implementations at frequencies below 18 GHz. This paper describes the implementation using a relatively new multi-layer microfabrication process resulting in a small, 6x6 element, dual-linear polarized array with beamformer that operates from 8 to 40 GHz. The beamformer includes baluns that feed the dual-polarized differential antenna elements and reactive splitter networks that also cover the full frequency range of operation. This antenna array serves as a reflector feed for a multi-band instrument designed to measure snow water equivalent (SWE) from airborne platforms. The instrument has both radar and radiome try capability at multiple frequencies. Scattering-parameter and time-domain measurements have been used to characterize the array feed. Radiation patterns of the antenna have been measured and are compared to simulation. To the best of the authors' knowledge, this work represents the most integrated multi-octave millimeter-wave antenna feed fabricated to date.

  10. Analyzing Responses of Chemical Sensor Arrays

    Science.gov (United States)

    Zhou, Hanying

    2007-01-01

    NASA is developing a third-generation electronic nose (ENose) capable of continuous monitoring of the International Space Station s cabin atmosphere for specific, harmful airborne contaminants. Previous generations of the ENose have been described in prior NASA Tech Briefs issues. Sensor selection is critical in both (prefabrication) sensor material selection and (post-fabrication) data analysis of the ENose, which detects several analytes that are difficult to detect, or that are at very low concentration ranges. Existing sensor selection approaches usually include limited statistical measures, where selectivity is more important but reliability and sensitivity are not of concern. When reliability and sensitivity can be major limiting factors in detecting target compounds reliably, the existing approach is not able to provide meaningful selection that will actually improve data analysis results. The approach and software reported here consider more statistical measures (factors) than existing approaches for a similar purpose. The result is a more balanced and robust sensor selection from a less than ideal sensor array. The software offers quick, flexible, optimal sensor selection and weighting for a variety of purposes without a time-consuming, iterative search by performing sensor calibrations to a known linear or nonlinear model, evaluating the individual sensor s statistics, scoring the individual sensor s overall performance, finding the best sensor array size to maximize class separation, finding optimal weights for the remaining sensor array, estimating limits of detection for the target compounds, evaluating fingerprint distance between group pairs, and finding the best event-detecting sensors.

  11. The Parkes Pulsar Timing Array Project

    CERN Document Server

    Manchester, R N; Bailes, M; Coles, W A; van Straten, W; Keith, M J; Shannon, R M; Bhat, N D R; Brown, A; Burke-Spolaor, S G; Champion, D J; Chaudhary, A; Edwards, R T; Hampson, G; Hotan, A W; Jameson, A; Jenet, F A; Kesteven, M J; Khoo, J; Kocz, J; Maciesiak, K; Oslowski, S; Ravi, V; Reynolds, J R; Sarkissian, J M; Verbiest, J P W; Wen, Z L; Wilson, W E; Yardley, D; Yan, W M; You, X P

    2012-01-01

    A "pulsar timing array" (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of "global" phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 millisecond pulsars is being observed at three radio-frequency bands, 50cm (~700 MHz), 20cm (~1400 MHz) and 10cm (~3100 MHz), with observations at intervals of 2 - 3 weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For...

  12. RADIOMETRIC CALIBRATION OF MARS HiRISE HIGH RESOLUTION IMAGERY BASED ON FPGA

    Directory of Open Access Journals (Sweden)

    Y. Hou

    2016-06-01

    Full Text Available Due to the large data amount of HiRISE imagery, traditional radiometric calibration method is not able to meet the fast processing requirements. To solve this problem, a radiometric calibration system of HiRISE imagery based on field program gate array (FPGA is designed. The montage gap between two channels caused by gray inconsistency is removed through histogram matching. The calibration system is composed of FPGA and DSP, which makes full use of the parallel processing ability of FPGA and fast computation as well as flexible control characteristic of DSP. Experimental results show that the designed system consumes less hardware resources and the real-time processing ability of radiometric calibration of HiRISE imagery is improved.

  13. Radiometric Calibration of Mars HiRISE High Resolution Imagery Based on Fpga

    Science.gov (United States)

    Hou, Yifan; Geng, Xun; Xing, Shuai; Tang, Yonghe; Xu, Qing

    2016-06-01

    Due to the large data amount of HiRISE imagery, traditional radiometric calibration method is not able to meet the fast processing requirements. To solve this problem, a radiometric calibration system of HiRISE imagery based on field program gate array (FPGA) is designed. The montage gap between two channels caused by gray inconsistency is removed through histogram matching. The calibration system is composed of FPGA and DSP, which makes full use of the parallel processing ability of FPGA and fast computation as well as flexible control characteristic of DSP. Experimental results show that the designed system consumes less hardware resources and the real-time processing ability of radiometric calibration of HiRISE imagery is improved.

  14. Optimizing Chemical Sensor Array Sizes

    International Nuclear Information System (INIS)

    Optimal selection of array sensors for a chemical sensing application is a nontrivial task. It is commonly believed that ''more is better'' when choosing the number of sensors required to achieve good chemical selectivity. However, cost and system complexity issues point towards the choice of small arrays. A quantitative array optimization is carried out to explore the selectivity of arrays of partially-selective chemical sensors as a function of array size. It is shown that modest numbers (dozens) of target analytes are completely distinguished with a range of arrays sizes. However, the array selectivity and the robustness against sensor sensitivity variability are significantly degraded if the array size is increased above a certain number of sensors, so that relatively small arrays provide the best performance. The results also suggest that data analyses for very large arrays of partially-selective sensors will be optimized by separately anal yzing small sensor subsets

  15. The plastic scintillator detector calibration circuit for DAMPE

    Science.gov (United States)

    Yang, Haibo; Kong, Jie; Zhao, Hongyun; Su, Hong

    2016-07-01

    The Dark Matter Particle Explorer (DAMPE) is being constructed as a scientific satellite to observe high energy cosmic rays in space. Plastic scintillator detector array (PSD), developed by Institute of Modern Physics, Chinese Academy of Sciences (IMPCAS), is one of the most important parts in the payload of DAMPE which is mainly used for the study of dark matter. As an anti-coincidence detector, and a charged-particle identification detector, the PSD has a total of 360 electronic readout channels, which are distributed at four sides of PSD using four identical front end electronics (FEE). Each FEE reads out 90 charge signals output by the detector. A special calibration circuit is designed in FEE. FPGA is used for on-line control, enabling the calibration circuit to generate the pulse signal with known charge. The generated signal is then sent to the FEE for calibration and self-test. This circuit mainly consists of DAC, operation amplifier, analog switch, capacitance and resistance. By using controllable step pulse, the charge can be coupled to the charge measuring chip using the small capacitance. In order to fulfill the system's objective of large dynamic range, the FEE is required to have good linearity. Thus, the charge-controllable signal is needed to do sweep test on all channels in order to obtain the non-linear parameters for off-line correction. On the other hand, the FEE will run on the satellite for three years. The changes of the operational environment and the aging of devices will lead to parameter variation of the FEE, highlighting the need for regular calibration. The calibration signal generation circuit also has a compact structure and the ability to work normally, with the PSD system's voltage resolution being higher than 0.6%.

  16. Recommended Inorganic Chemicals for Calibration.

    Science.gov (United States)

    Moody, John R.; And Others

    1988-01-01

    All analytical techniques depend on the use of calibration chemicals to relate analyte concentration to instrumental parameters. Discusses the preparation of standard solutions and provides a critical evaluation of available materials. Lists elements by group and discusses the purity and uses of each. (MVL)

  17. Reliability-Based Code Calibration

    DEFF Research Database (Denmark)

    Faber, M.H.; Sørensen, John Dalsgaard

    2003-01-01

    . Thereafter the code calibration problem is presented in its principal decision theoretical form and it is discussed how acceptable levels of failure probability (or target reliabilities) may be established. Furthermore suggested values for acceptable annual failure probabilities are given for ultimate...

  18. Measurement System and Calibration report

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    This Measurement System & Calibration report is describing DTU’s measurement system installed at a specific wind turbine. A major part of the sensors has been installed by others (see [1]) the rest of the sensors have been installed by DTU. The results of the measurements, described in this report...

  19. Measurement System and Calibration report

    DEFF Research Database (Denmark)

    Vesth, Allan; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...

  20. Scalar Calibration of Vector Magnetometers

    DEFF Research Database (Denmark)

    Merayo, José M.G.; Brauer, Peter; Primdahl, Fritz;

    2000-01-01

    the parameters for a given data set. Therefore, a magnetometer may be characterized inexpensively in the Earth's magnetic-field environment. This procedure has been used successfully in the pre-flight calibration of the state-of-the-art magnetometers on board the magnetic mapping satellites Orsted, Astrid-2...

  1. Combined Approach for Nonuniformity Correction in Infrared Focal Plane Array

    Institute of Scientific and Technical Information of China (English)

    XUE Hui

    2009-01-01

    A new algorithm of nonuniformity correction for infrared focal plane array(IRFPA) is reported,which is a combined algorithm based on both the two-point correction and artificial neural networks correction.The combined algorithm is calibrated by two-point correction,and the calibrated correction coefficients are automatically modified by BP algorithm.So it is not only calibrated,but also real-time processed.In adaptive nonuniformity correction algorithm,the phenomena ghost artifact and target fade-out are avoided by edge extraction.In order to get intensified image,the modified median filters are adopted.The simulated data indicates the proposed scheme is an effective algorithm.

  2. Direct X-Ray Response Of Charge-Coupled Devices And Photodiode Linear Arrays

    Science.gov (United States)

    Launspach, J.; Bourgade, J. L.; Cavailler, C.; de Mascureau, J.; Mens, A.; Sauneuf, R.

    1986-08-01

    For x-ray calibration of detectors used on laser created plasma experiments we have developed and characterized two kinds of sources : classical continuous x-ray sources operating at 1.8 keV and 5.4 keV and a pulsed source obtained by modifying a plasma Focus device. Calibration data for x-ray Charge - Coupled Devices (CCD) and photodiode linear array cameras are presented.

  3. Imaging antenna arrays

    Science.gov (United States)

    Rutledge, D. B.; Muha, M. S.

    1982-01-01

    Many millimeter and far-infrared imaging systems are limited in sensitivity and speed because they depend on a single scanned element. Because of recent advances in planar detectors such as Schottky diodes, superconducting tunnel junctions, and microbolometers, an attractive approach to this problem is a planar antenna array with integrated detectors. A planar line antenna array and optical system for imaging has been developed. The significant advances are a 'reverse-microscope' optical configuration and a modified bow-tie antenna design. In the 'reverse-microscope' configuration, a lens is attached to the bottom of the substrate containing the antennas. Imaging is done through the substrate. This configuration eliminates the troublesome effects of substrate surface waves. The substrate lens has only a single refracting surface, making possible a virtually aplanatic system, with little spherical aberration or coma. The array is characterized by an optical transfer function that is easily measured. An array with 19 dB crosstalk levels between adjacent antennas has been tested and it was found that the array captured 50 percent of the available power. This imaging system was diffraction limited.

  4. Calibration of the RPC charge readout in the ARGO-YBJ experiment with the iso-gradient method

    International Nuclear Information System (INIS)

    The ARGO-YBJ experiment is a full coverage array of Resistive Plate Chambers (RPCs) with an active area of 5800 m2. In order to eliminate the response difference of the charge readout from the RPCs, a calibration procedure is carried out with the iso-gradient method. This method also allows the extension of the absolute calibration with the muon telescope including scintillation detectors to all the RPCs in the array. The overall systematic uncertainty in measurements of the number of particles by the RPCs is 10.7%. In general, the method gives results consistent with those from a totally different approach also used in the experiment

  5. Prey perception in feeding-current feeding copepods

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Goncalves, Rodrigo J.; Florian Couespel, Damien;

    2016-01-01

    We reply to the comments of Paffenhöfer and Jiang () who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey concentrati...

  6. Experimental Results of Site Calibration and Sensitivity Measurements in OTR for UWB Systems

    Science.gov (United States)

    Viswanadham, Chandana; Rao, P. Mallikrajuna

    2016-08-01

    System calibration and parameter accuracy measurement of electronic support measures (ESM) systems is a major activity, carried out by electronic warfare (EW) engineers. These activities are very critical and needs good understanding in the field of microwaves, antennas, wave propagation, digital and communication domains. EW systems are broad band, built with state-of-the art electronic hardware, installed on different varieties of military platforms to guard country's security from time to time. EW systems operate in wide frequency ranges, typically in the order of thousands of MHz, hence these are ultra wide band (UWB) systems. Few calibration activities are carried within the system and in the test sites, to meet the accuracies of final specifications. After calibration, parameters are measured for their accuracies either in feed mode by injecting the RF signals into the front end or in radiation mode by transmitting the RF signals on to system antenna. To carry out these activities in radiation mode, a calibrated open test range (OTR) is necessary in the frequency band of interest. Thus site calibration of OTR is necessary to be carried out before taking up system calibration and parameter measurements. This paper presents the experimental results of OTR site calibration and sensitivity measurements of UWB systems in radiation mode.

  7. FEL phased array configurations

    Science.gov (United States)

    Shellan, Jeffrey B.

    1986-01-01

    The advantages and disadvantages of various phased array and shared aperture concepts for FEL configurations are discussed. Consideration is given to the characteristics of intra- and inter-micropulse phasing; intra-macropulse phasing; an internal coupled resonator configuration; and an injection locked oscillator array. The use of a master oscillator power amplifier (MOPA) configuration with multiple or single master oscillators for FELs is examined. The venetian blind, rotating plate, single grating, and grating rhomb shared aperture concepts are analyzed. It is noted that the shared aperture approach using a grating rhomb and the MOPA concept with a single master oscillator and a coupled resonator are useful for FEL phased array configurations; and the MOPA concept is most applicable.

  8. Wireless Josephson Junction Arrays

    Science.gov (United States)

    Adams, Laura

    2015-03-01

    We report low temperature, microwave transmission measurements on a wireless two- dimensional network of Josephson junction arrays composed of superconductor-insulator -superconductor tunnel junctions. Unlike their biased counterparts, by removing all electrical contacts to the arrays and superfluous microwave components and interconnects in the transmission line, we observe new collective behavior in the transmission spectra. In particular we will show emergent behavior that systematically responds to changes in microwave power at fixed temperature. Likewise we will show the dynamic and collective response of the arrays while tuning the temperature at fixed microwave power. We discuss these spectra in terms of the Berezinskii-Kosterlitz-Thouless phase transition and Shapiro steps. We gratefully acknowledge the support Prof. Steven Anlage at the University of Maryland and Prof. Allen Goldman at the University of Minnesota. Physics and School of Engineering and Applied Sciences.

  9. Spallation reactions studied with 4-detector arrays

    Indian Academy of Sciences (India)

    J Galin

    2001-07-01

    Recently there has been a renewed interest in the study of spallation reactions in basic nuclear physics as well as in potential applications. Spallation reactions induced by light projectiles (protons, antiprotons, pions, etc.) in the GeV range allow the formation of hot nuclei which do not suffer the collective excitations (compression, rotation, deformation) unavoidable when using massive projectiles. Such nuclei provide an ideal testbench for probing their decay as a function of excitation energy. In these investigations, 4-detector arrays for charged particles and neutrons play a major role in the event-by-event sorting according to the excitation energy of the nucleus. Spallation reactions induced on heavy nuclei allow the conversion of the incident GeV proton into several tens of evaporated neutrons. The neutron production in thick targets has been investigated in great detail thanks to the use of high efficiency neutron detector arrays. When scattered on samples of inert or biological materials, these neutrons can be used to study details of the material structure. They could also be utilized for the transmutation of long-lived nuclear wastes or for the feeding of sub-critical nuclear reactors. The role of different types of multi-detector arrays is highlighted in this paper. Several references are also given for different uses of high efficiency neutron detectors in other contexts.

  10. Array of Bolometers for Submillimeter- Wavelength Operation

    Science.gov (United States)

    Bock, James; Turner, Anthony

    2007-01-01

    A feed-horn-coupled monolithic array of micromesh bolometers is undergoing development for use in a photometric camera. The array is designed for conducting astrophysical observations in a wavelength band centered at 350 m. The bolometers are improved versions of previously developed bolometers comprising metalized Si3N4 micromesh radiation absorbers coupled with neutron- transmutation-doped Ge thermistors. Incident radiation heats the absorbers above a base temperature, changing the electrical resistance of each thermistor. In the present array of improved bolometers (see figure), the thermistors are attached to the micromesh absorbers by indium bump bonds and are addressed by use of lithographed, vapor-deposited electrical leads. This architecture reduces the heat capacity and minimizes the thermal conductivity to 1/20 and 1/300, respectively, of earlier versions of these detectors, with consequent improvement in sensitivity and speed of response. The micromesh bolometers, intended to operate under an optical background set by thermal emission from an ambient-temperature space-borne telescope, are designed such that the random arrival of photons ("photon noise") dominates the noise sources arising from the detector and readout electronics. The micromesh is designed to be a highly thermally and optically efficient absorber with a limiting response time of about 100 s. The absorber and thermistor heat capacity are minimized in order to give rapid speed of response. Due to the minimization of the absorber volume, the dominant source of heat capacity arises from the thermistor.

  11. Transducer Development and Characterization for Underwater Acoustic Neutrino Detection Calibration

    Science.gov (United States)

    Saldaña, María; Llorens, Carlos D.; Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

    2016-01-01

    A short bipolar pressure pulse with “pancake” directivity is produced and propagated when an Ultra-High Energy (UHE) neutrino interacts with a nucleus in water. Nowadays, acoustic sensor networks are being deployed in deep seas to detect this phenomenon as a first step toward building a neutrino telescope. In order to study the feasibility of the method, it is critical to have a calibrator that is able to mimic the neutrino signature. In previous works the possibility of using the acoustic parametric technique for this aim was proven. In this study, the array is operated at a high frequency and, by means of the parametric effect, the emission of the low-frequency acoustic bipolar pulse is generated mimicking the UHE neutrino acoustic pulse. To this end, the development of the transducer to be used in the parametric array is described in all its phases. The transducer design process, the characterization tests for the bare piezoelectric ceramic, and the addition of backing and matching layers are presented. The efficiencies and directivity patterns obtained for both primary and parametric beams confirm that the design of the proposed calibrator meets all the requirements for the emitter. PMID:27490547

  12. Transducer Development and Characterization for Underwater Acoustic Neutrino Detection Calibration.

    Science.gov (United States)

    Saldaña, María; Llorens, Carlos D; Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

    2016-01-01

    A short bipolar pressure pulse with "pancake" directivity is produced and propagated when an Ultra-High Energy (UHE) neutrino interacts with a nucleus in water. Nowadays, acoustic sensor networks are being deployed in deep seas to detect this phenomenon as a first step toward building a neutrino telescope. In order to study the feasibility of the method, it is critical to have a calibrator that is able to mimic the neutrino signature. In previous works the possibility of using the acoustic parametric technique for this aim was proven. In this study, the array is operated at a high frequency and, by means of the parametric effect, the emission of the low-frequency acoustic bipolar pulse is generated mimicking the UHE neutrino acoustic pulse. To this end, the development of the transducer to be used in the parametric array is described in all its phases. The transducer design process, the characterization tests for the bare piezoelectric ceramic, and the addition of backing and matching layers are presented. The efficiencies and directivity patterns obtained for both primary and parametric beams confirm that the design of the proposed calibrator meets all the requirements for the emitter. PMID:27490547

  13. Transducer Development and Characterization for Underwater Acoustic Neutrino Detection Calibration.

    Science.gov (United States)

    Saldaña, María; Llorens, Carlos D; Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

    2016-01-01

    A short bipolar pressure pulse with "pancake" directivity is produced and propagated when an Ultra-High Energy (UHE) neutrino interacts with a nucleus in water. Nowadays, acoustic sensor networks are being deployed in deep seas to detect this phenomenon as a first step toward building a neutrino telescope. In order to study the feasibility of the method, it is critical to have a calibrator that is able to mimic the neutrino signature. In previous works the possibility of using the acoustic parametric technique for this aim was proven. In this study, the array is operated at a high frequency and, by means of the parametric effect, the emission of the low-frequency acoustic bipolar pulse is generated mimicking the UHE neutrino acoustic pulse. To this end, the development of the transducer to be used in the parametric array is described in all its phases. The transducer design process, the characterization tests for the bare piezoelectric ceramic, and the addition of backing and matching layers are presented. The efficiencies and directivity patterns obtained for both primary and parametric beams confirm that the design of the proposed calibrator meets all the requirements for the emitter.

  14. The Submillimeter Array

    CERN Document Server

    Ho, P T P; Lo, K Y; Ho, Paul T.P.; Moran, James M.; Lo, Kwok Yung

    2004-01-01

    The Submillimeter Array (SMA), a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total of eight 6-m telescopes comprise the array, which will cover the frequency range of 180-900 GHz. All eight telescopes have been deployed and are operational. First scientific results utilizing the three receiver bands at 230, 345, and 690 GHz have been obtained and are presented in the accompanying papers.

  15. Photovoltaic array performance model.

    Energy Technology Data Exchange (ETDEWEB)

    Kratochvil, Jay A.; Boyson, William Earl; King, David L.

    2004-08-01

    This document summarizes the equations and applications associated with the photovoltaic array performance model developed at Sandia National Laboratories over the last twelve years. Electrical, thermal, and optical characteristics for photovoltaic modules are included in the model, and the model is designed to use hourly solar resource and meteorological data. The versatility and accuracy of the model has been validated for flat-plate modules (all technologies) and for concentrator modules, as well as for large arrays of modules. Applications include system design and sizing, 'translation' of field performance measurements to standard reporting conditions, system performance optimization, and real-time comparison of measured versus expected system performance.

  16. Soldered solar arrays

    Science.gov (United States)

    Allen, H. C.

    1982-06-01

    The ability of soldered interconnects to withstand a combination of long life and severe environmental conditions was investigated. Improvements in joint life from the use of solder mixes appropriate to low temperature conditons were studied. Solder samples were placed in a 150 C oven for 5 weeks (= 12 yr at 80 C, or 24 at 70 C according to Arrhenius's rule). Conventional and high solder melting point array samples underwent 1000 thermal cycles between -186 and 100 C. Results show that conventional and lead rich soldered arrays can survive 10 yr geostationary orbit missions.

  17. Wire Array Photovoltaics

    Science.gov (United States)

    Turner-Evans, Dan

    Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

  18. Radiometric Calibration of Osmi Imagery Using Solar Calibration

    Science.gov (United States)

    Lee, Dong-Han; Kim, Yong-Seung

    2000-12-01

    OSMI (Ocean Scanning Multi-Spectral Imager) raw image data (Level 0) were acquired and radiometrically corrected. We have applied two methods, using solar & dark calibration data from OSMI sensor and comparing with the SeaWiFS data, to the radiometric correction of OSMI raw image data. First, we could get the values of the gain and the offset for each pixel and each band from comparing the solar & dark calibration data with the solar input radiance values, calculated from the transmittance, BRDF (Bidirectional Reflectance Distribution Function) and the solar incidence angle (¥â,¥è) of OSMI sensor. Applying this calibration data to OSMI raw image data, we got the two odd results, the lower value of the radiometric corrected image data than the expected value, and the Venetian Blind Effect in the radiometric corrected image data. Second, we could get the reasonable results from comparing OSMI raw image data with the SeaWiFS data, and get a new problem of OSMI sensor.

  19. SMAP RADAR Calibration and Validation

    Science.gov (United States)

    West, R. D.; Jaruwatanadilok, S.; Chaubel, M. J.; Spencer, M.; Chan, S. F.; Chen, C. W.; Fore, A.

    2015-12-01

    The Soil Moisture Active Passive (SMAP) mission launched on Jan 31, 2015. The mission employs L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Immediately following launch, there was a three month instrument checkout period, followed by six months of level 1 (L1) calibration and validation. In this presentation, we will discuss the calibration and validation activities and results for the L1 radar data. Early SMAP radar data were used to check commanded timing parameters, and to work out issues in the low- and high-resolution radar processors. From April 3-13 the radar collected receive only mode data to conduct a survey of RFI sources. Analysis of the RFI environment led to a preferred operating frequency. The RFI survey data were also used to validate noise subtraction and scaling operations in the radar processors. Normal radar operations resumed on April 13. All radar data were examined closely for image quality and calibration issues which led to improvements in the radar data products for the beta release at the end of July. Radar data were used to determine and correct for small biases in the reported spacecraft attitude. Geo-location was validated against coastline positions and the known positions of corner reflectors. Residual errors at the time of the beta release are about 350 m. Intra-swath biases in the high-resolution backscatter images are reduced to less than 0.3 dB for all polarizations. Radiometric cross-calibration with Aquarius was performed using areas of the Amazon rain forest. Cross-calibration was also examined using ocean data from the low-resolution processor and comparing with the Aquarius wind model function. Using all a-priori calibration constants provided good results with co-polarized measurements matching to better than 1 dB, and cross-polarized measurements matching to about 1 dB in the beta release. During the

  20. Enteral Tube Feeding and Pneumonia

    Science.gov (United States)

    Gray, David Sheridan; Kimmel, David

    2006-01-01

    To determine the effects of enteral tube feeding on the incidence of pneumonia, we performed a retrospective review of all clients at our institution who had gastrostomy or jejunostomy tubes placed over a 10-year period. Ninety-three subjects had a history of pneumonia before feeding tube insertion. Eighty had gastrostomy and 13, jejunostomy…

  1. Dual-frequency dual-polarized stacked patch microstrip arrays: An investigation of their suitability for soil-moisture remote-sensing applications

    Science.gov (United States)

    Kona, Keerti Sruta

    The objective of this research is to develop design and analysis procedures for dual-frequency dual-polarized microstrip arrays applicable to future spaceborne remote sensing missions. In particular this thesis focuses on two main applications: Application 1. Design of light-weight L-band standalone planar array for soil moisture and sea-surface salinity measurements. We then investigate the possibility of a stacked patch array topology with L-band array elements for use as feed to 12m offset reflector. Application 2. Development of feed array concept for 30m symmetric reflector. The principal contributions of this research has been investigation of novel dual-band and dual-polarization array designs that can comply with the demanding specifications. Novel probe feeding methods for microstrip elements to achieve the best array performance are identified. Most importantly, "proof-of-concept" scaled models of the array designs were experimentally and numerically verified for a given set of specifications. A sixteen element microstrip stacked patch array with combined L-band active (radar) and passive (radiometer) frequencies for use in airborne sensors operating on standalone aircrafts has been optimized, fabricated and tested for application 1. Sub-cell FDTD method was applied for accurately modeling thin radomes and multilayer dielectrics covering such aperture type antennas in space applications. From the design and performance study of the L-band array, we have shown that it is feasible to use optimized stacked patch arrays as alternatives to conventionally used feed horns for offset reflectors. For application 2, a dual-stack patch array feed is identified that can synthesize long rectangular apertures with matched beams for two frequencies on the reflector surface. An experimental prototype scaled feed was designed, built and also integrated with a scaled 3.65m reflector antenna thus demonstrating the overall system feasibility.

  2. Improved Circuits with Capacitive Feedback for Readout Resistive Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Óscar Oballe-Peinado

    2016-01-01

    Full Text Available One of the most suitable ways of distributing a resistive sensor array for reading is an array with M rows and N columns. This allows reduced wiring and a certain degree of parallelism in the implementation, although it also introduces crosstalk effects. Several types of circuits can carry out the analogue-digital conversion of this type of sensors. This article focuses on the use of operational amplifiers with capacitive feedback and FPGAs for this task. Specifically, modifications of a previously reported circuit are proposed to reduce the errors due to the non-idealities of the amplifiers and the I/O drivers of the FPGA. Moreover, calibration algorithms are derived from the analysis of the proposed circuitry to reduce the crosstalk error and improve the accuracy. Finally, the performances of the proposals is evaluated experimentally on an array of resistors and for different ranges.

  3. Improved Circuits with Capacitive Feedback for Readout Resistive Sensor Arrays.

    Science.gov (United States)

    Oballe-Peinado, Óscar; Vidal-Verdú, Fernando; Sánchez-Durán, José A; Castellanos-Ramos, Julián; Hidalgo-López, José A

    2016-01-01

    One of the most suitable ways of distributing a resistive sensor array for reading is an array with M rows and N columns. This allows reduced wiring and a certain degree of parallelism in the implementation, although it also introduces crosstalk effects. Several types of circuits can carry out the analogue-digital conversion of this type of sensors. This article focuses on the use of operational amplifiers with capacitive feedback and FPGAs for this task. Specifically, modifications of a previously reported circuit are proposed to reduce the errors due to the non-idealities of the amplifiers and the I/O drivers of the FPGA. Moreover, calibration algorithms are derived from the analysis of the proposed circuitry to reduce the crosstalk error and improve the accuracy. Finally, the performances of the proposals is evaluated experimentally on an array of resistors and for different ranges. PMID:26821024

  4. Calibration of the solar radio spectrometer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper shows some improvements and new results of calibration of Chinese solar radio spectrometer by analyzing the daily calibration data recorded in the period of 1997-2007. First, the calibration coefficient is fitted for three bands (1.0-2.0 GHz, 2.6-3.8 GHz, 5.2-7.6 GHz) of the spectrometer by using the moving-average method confined by the property of the daily calibration data. By this calibration coefficient, the standard deviation of the calibration result was less than 10 sfu for 95% frequencies of 2.6-3.8 GHz band in 2003. This result is better than that calibrated with the constant coefficient. Second, the calibration coefficient is found in good correlation with local air temperature for most frequencies of 2.6-3.8 GHz band. Moreover, these results are helpful in the research of the quiet solar radio emission.

  5. Calibration of the solar radio spectrometer

    Institute of Scientific and Technical Information of China (English)

    TAN ChengMing; YAN YiHua; TAN BaoLin; XU GuiRong

    2009-01-01

    This paper shows some improvements and new results of calibration of Chinese solar radio spectrom-eter by analyzing the daily calibration data recorded in the period of 1997-2007. First, the calibration coefficient is fitted for three bands (1.0-2.0 GHz, 2.6-3.8 GHz, 5.2-7.6 GHz) of the spectrometer by using the moving-average method confined by the property of the daily calibration data. By this calibration coefficient, the standard deviation of the calibration result was less than 10 sfu for 95% frequencies of 2.6-3.8 GHz band in 2003. This result is better than that calibrated with the constant coefficient. Second, the calibration coefficient is found in good correlation with local air temperature for most frequencies of 2.6-3.8 GHz band. Moreover, these results are helpful in the research of the quiet solar radio emission.

  6. Attitude Sensor and Gyro Calibration for Messenger

    Science.gov (United States)

    O'Shaughnessy, Daniel; Pittelkau, Mark E.

    2007-01-01

    The Redundant Inertial Measurement Unit Attitude Determination/Calibration (RADICAL(TM)) filter was used to estimate star tracker and gyro calibration parameters using MESSENGER telemetry data from three calibration events. We present an overview of the MESSENGER attitude sensors and their configuration is given, the calibration maneuvers are described, the results are compared with previous calibrations, and variations and trends in the estimated calibration parameters are examined. The warm restart and covariance bump features of the RADICAL(TM) filter were used to estimate calibration parameters from two disjoint telemetry streams. Results show that the calibration parameters converge faster with much less transient variation during convergence than when the filter is cold-started at the start of each telemetry stream.

  7. Crop physiology calibration in the CLM

    Directory of Open Access Journals (Sweden)

    I. Bilionis

    2015-04-01

    scalable and adaptive scheme based on sequential Monte Carlo (SMC. The model showed significant improvement of crop productivity with the new calibrated parameters. We demonstrate that the calibrated parameters are applicable across alternative years and different sites.

  8. Calibration and Validation of Measurement System

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Riemann, Sven; Knapp, Wilfried

    The report deals with the calibration of the measuring equipment on board the Wave Dragon, Nissum Bredning prototype.......The report deals with the calibration of the measuring equipment on board the Wave Dragon, Nissum Bredning prototype....

  9. A geometric calibration method for inverse geometry computed tomography using P-matrices

    Science.gov (United States)

    Slagowski, Jordan M.; Dunkerley, David A. P.; Hatt, Charles R.; Speidel, Michael A.

    2016-03-01

    Accurate and artifact free reconstruction of tomographic images requires precise knowledge of the imaging system geometry. This work proposes a novel projection matrix (P-matrix) based calibration method to enable C-arm inverse geometry CT (IGCT). The method is evaluated for scanning-beam digital x-ray (SBDX), a C-arm mounted inverse geometry fluoroscopic technology. A helical configuration of fiducials is imaged at each gantry angle in a rotational acquisition. For each gantry angle, digital tomosynthesis is performed at multiple planes and a composite image analogous to a cone-beam projection is generated from the plane stack. The geometry of the C-arm, source array, and detector array is determined at each angle by constructing a parameterized 3D-to-2D projection matrix that minimizes the sum-of-squared deviations between measured and projected fiducial coordinates. Simulations were used to evaluate calibration performance with translations and rotations of the source and detector. In a geometry with 1 mm translation of the central ray relative to the axis-of-rotation and 1 degree yaw of the detector and source arrays, the maximum error in the recovered translational parameters was 0.4 mm and maximum error in the rotation parameter was 0.02 degrees. The relative rootmean- square error in a reconstruction of a numerical thorax phantom was 0.4% using the calibration method, versus 7.7% without calibration. Changes in source-detector-distance were the most challenging to estimate. Reconstruction of experimental SBDX data using the proposed method eliminated double contour artifacts present in a non-calibrated reconstruction. The proposed IGCT geometric calibration method reduces image artifacts when uncertainties exist in system geometry.

  10. Radiation sterilization of livestock feeds

    International Nuclear Information System (INIS)

    The radiation sterilization of livestock feeds is not much used presently because the process is not known well, and the cost is relatively high. However, its effect of sterilization is absolute, the radiation-sterilized feeds are safe in both nutrition and toxicity, and do not affect the appetite of livestocks, and the radiation energy required is small. In the future, as in the sterilization of medical supplies, feed radiation sterilization plants should be established, to stabilize livestock industry and to contribute to the health control of experimental animals. The following matters are described: radiation, comparison between radiation sterilization and other sterilization methods, the practice of feed radiation sterilization, the adverse effects of radiation sterilization, economic aspect, and the situation of feed radiation sterilization in various countries. (Mori, K.)

  11. Calibration of Gamma-ray Burst Polarimeter POLAR

    CERN Document Server

    Xiao, H L; Bao, T W; Batsch, T; Bernasconi, T; Cernuda, I; Chai, J Y; Dong, Y W; Gauvin, N; Kole, M; Kong, M N; Kong, S W; Li, L; Liu, J T; Liu, X; Marcinkowski, R; Orsi, S; Pohl, M; Produit, N; Rapin, D; Rutczynska, A; Rybka, D; Shi, H L; Song, L M; Sun, J C; Szabelski, J; Wu, B B; Wang, R J; Wen, X; Xu, H H; Zhang, L; Zhang, L Y; Zhang, S N; Zhang, X F; Zhang, Y J; Zwolinska, A

    2015-01-01

    Gamma Ray Bursts (GRBs) are the strongest explosions in the universe which might be associated with creation of black holes. Magnetic field structure and burst dynamics may influence polarization of the emitted gamma-rays. Precise polarization detection can be an ultimate tool to unveil the true GRB mechanism. POLAR is a space-borne Compton scattering detector for precise measurements of the GRB polarization. It consists of a 40$\\times$40 array of plastic scintillator bars read out by 25 multi-anode PMTs (MaPMTs). It is scheduled to be launched into space in 2016 onboard of the Chinese space laboratory TG2. We present a dedicated methodology for POLAR calibration and some calibration results based on the combined use of the laboratory radioactive sources and polarized X-ray beams from the European Synchrotron Radiation Facility. They include calibration of the energy response, computation of the energy conversion factor vs. high voltage as well as determination of the threshold values, crosstalk contributions...

  12. Design of Experiments, Model Calibration and Data Assimilation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Brian J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-30

    This presentation provides an overview of emulation, calibration and experiment design for computer experiments. Emulation refers to building a statistical surrogate from a carefully selected and limited set of model runs to predict unsampled outputs. The standard kriging approach to emulation of complex computer models is presented. Calibration refers to the process of probabilistically constraining uncertain physics/engineering model inputs to be consistent with observed experimental data. An initial probability distribution for these parameters is updated using the experimental information. Markov chain Monte Carlo (MCMC) algorithms are often used to sample the calibrated parameter distribution. Several MCMC algorithms commonly employed in practice are presented, along with a popular diagnostic for evaluating chain behavior. Space-filling approaches to experiment design for selecting model runs to build effective emulators are discussed, including Latin Hypercube Design and extensions based on orthogonal array skeleton designs and imposed symmetry requirements. Optimization criteria that further enforce space-filling, possibly in projections of the input space, are mentioned. Designs to screen for important input variations are summarized and used for variable selection in a nuclear fuels performance application. This is followed by illustration of sequential experiment design strategies for optimization, global prediction, and rare event inference.

  13. Astrid-2 EMMA Magnetic Calibration

    DEFF Research Database (Denmark)

    Merayo, José M.G.; Brauer, Peter; Risbo, Torben;

    1998-01-01

    The Swedish micro-satellite Astrid-2 contains a tri-axial fluxgate magnetometer with the sensor co-located with a Technical University of Denmark (DTU) star camera for absolute attitude, and extended about 0.9 m on a hinged boom. The magnetometer is part of the RIT EMMA electric and magnetic fields...... experiment built as a collaboration between the DTU, Department of Automation and the Department of Plasma Physics, The Alfvenlaboratory, Royal Institute of Technology (RIT), Stockholm. The final magnetic calibration of the Astrid-2 satellite was done at the Lovoe Magnetic Observatory under the Geological...... Survey of Sweden near Stockholm on the night of May 15.-16., 1997. The magnetic calibration and the intercalibration between the star camera and the magnetic sensor was performed by measuring the Earth's magnetic field and simultaneously observing the star sky with the camera. The rotation matrix between...

  14. Array Theory and Nial

    DEFF Research Database (Denmark)

    Falster, Peter; Jenkins, Michael

    1999-01-01

    This report is the result of collaboration between the authors during the first 8 months of 1999 when M. Jenkins was visiting professor at DTU. The report documents the development of a tool for the investigation of array theory concepts and in particular presents various approaches to choose pri...

  15. Cantilever array sensors

    Directory of Open Access Journals (Sweden)

    Hans Peter Lang

    2005-04-01

    Full Text Available Miniaturized microfabricated sensors have enormous potential in gas detection, biochemical analysis, medical applications, quality and process control, and product authenticity issues. Here, we highlight an ultrasensitive mechanical way of converting (bio-chemical or physical processes into a recordable signal using microfabricated cantilever arrays.

  16. Calibration of a Parallel Kinematic Machine Tool

    Institute of Scientific and Technical Information of China (English)

    HE Xiao-mei; DING Hong-sheng; FU Tie; XIE Dian-huang; XU Jin-zhong; LI Hua-feng; LIU Hui-lin

    2006-01-01

    A calibration method is presented to enhance the static accuracy of a parallel kinematic machine tool by using a coordinate measuring machine and a laser tracker. According to the established calibration model and the calibration experiment, the factual 42 kinematic parameters of BKX-I parallel kinematic machine tool are obtained. By circular tests the comparison is made between the calibrated and the uncalibrated parameters and shows that there is 80% improvement in accuracy of this machine tool.

  17. Binary Classifier Calibration: Non-parametric approach

    OpenAIRE

    Naeini, Mahdi Pakdaman; Cooper, Gregory F.; Hauskrecht, Milos

    2014-01-01

    Accurate calibration of probabilistic predictive models learned is critical for many practical prediction and decision-making tasks. There are two main categories of methods for building calibrated classifiers. One approach is to develop methods for learning probabilistic models that are well-calibrated, ab initio. The other approach is to use some post-processing methods for transforming the output of a classifier to be well calibrated, as for example histogram binning, Platt scaling, and is...

  18. GREAT/SOFIA atmospheric calibration

    OpenAIRE

    Guan, Xin; Stutzki, Jürgen; Graf, Urs U.; Güsten, Rolf; Okada, Yoko; Torres, Miguel Angel Requena; Simon, Robert; Wiesemeyer, Helmut

    2012-01-01

    The GREAT observations need frequency-selective calibration across the passband for the residual atmospheric opacity at flight altitude. At these altitudes the atmospheric opacity has both narrow and broad spectral features. To determine the atmospheric transmission at high spectral resolution, GREAT compares the observed atmospheric emission with atmospheric model predictions, and therefore depends on the validity of the atmospheric models. We discusse the problems identified in this compari...

  19. Colour calibration for colour reproduction

    OpenAIRE

    Emmel, P.; R. D. Hersch

    2000-01-01

    Due to the proliferation of low-cost colour devices (digital colour cameras, scanners, printers etc.) during the last few years, colour calibration has become an important issue. Such devices should faithfully reproduce colour images, but experience shows they don't. Among the main reasons, we note the diversity of acquisition, display and printing technologies which makes standardization difficult. Each device has a different gamut, i.e. a different set of colours that it can acquire or repr...

  20. Calibrating thermal behavior of electronics

    Science.gov (United States)

    Chainer, Timothy J.; Parida, Pritish R.; Schultz, Mark D.

    2016-05-31

    A method includes determining a relationship between indirect thermal data for a processor and a measured temperature associated with the processor, during a calibration process, obtaining the indirect thermal data for the processor during actual operation of the processor, and determining an actual significant temperature associated with the processor during the actual operation using the indirect thermal data for the processor during actual operation of the processor and the relationship.

  1. Unassisted 3D camera calibration

    Science.gov (United States)

    Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.

    2012-03-01

    With the rapid growth of 3D technology, 3D image capture has become a critical part of the 3D feature set on mobile phones. 3D image quality is affected by the scene geometry as well as on-the-device processing. An automatic 3D system usually assumes known camera poses accomplished by factory calibration using a special chart. In real life settings, pose parameters estimated by factory calibration can be negatively impacted by movements of the lens barrel due to shaking, focusing, or camera drop. If any of these factors displaces the optical axes of either or both cameras, vertical disparity might exceed the maximum tolerable margin and the 3D user may experience eye strain or headaches. To make 3D capture more practical, one needs to consider unassisted (on arbitrary scenes) calibration. In this paper, we propose an algorithm that relies on detection and matching of keypoints between left and right images. Frames containing erroneous matches, along with frames with insufficiently rich keypoint constellations, are detected and discarded. Roll, pitch yaw , and scale differences between left and right frames are then estimated. The algorithm performance is evaluated in terms of the remaining vertical disparity as compared to the maximum tolerable vertical disparity.

  2. Model Calibration in Watershed Hydrology

    Science.gov (United States)

    Yilmaz, Koray K.; Vrugt, Jasper A.; Gupta, Hoshin V.; Sorooshian, Soroosh

    2009-01-01

    Hydrologic models use relatively simple mathematical equations to conceptualize and aggregate the complex, spatially distributed, and highly interrelated water, energy, and vegetation processes in a watershed. A consequence of process aggregation is that the model parameters often do not represent directly measurable entities and must, therefore, be estimated using measurements of the system inputs and outputs. During this process, known as model calibration, the parameters are adjusted so that the behavior of the model approximates, as closely and consistently as possible, the observed response of the hydrologic system over some historical period of time. This Chapter reviews the current state-of-the-art of model calibration in watershed hydrology with special emphasis on our own contributions in the last few decades. We discuss the historical background that has led to current perspectives, and review different approaches for manual and automatic single- and multi-objective parameter estimation. In particular, we highlight the recent developments in the calibration of distributed hydrologic models using parameter dimensionality reduction sampling, parameter regularization and parallel computing.

  3. PACS photometer calibration block analysis

    CERN Document Server

    Moór, A; Kiss, Cs; Balog, Z; Billot, N; Marton, G

    2013-01-01

    The absolute stability of the PACS bolometer response over the entire mission lifetime without applying any corrections is about 0.5% (standard deviation) or about 8% peak-to-peak. This fantastic stability allows us to calibrate all scientific measurements by a fixed and time-independent response file, without using any information from the PACS internal calibration sources. However, the analysis of calibration block observations revealed clear correlations of the internal source signals with the evaporator temperature and a signal drift during the first half hour after the cooler recycling. These effects are small, but can be seen in repeated measurements of standard stars. From our analysis we established corrections for both effects which push the stability of the PACS bolometer response to about 0.2% (stdev) or 2% in the blue, 3% in the green and 5% in the red channel (peak-to-peak). After both corrections we still see a correlation of the signals with PACS FPU temperatures, possibly caused by parasitic h...

  4. CALIBRATION OF SEISMIC ATTRIBUTES FOR RESERVOIR CHARACTERIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Wayne D. Pennington

    2001-04-01

    The project, ''Calibration of Seismic Attributes for Reservoir Calibration,'' is on schedule and making unplanned discoveries in addition to those intended when the project commenced. The discoveries, planned and unplanned, can be grouped into four classes: pitfalls to avoid in interpretation of seismic attributes; suggested workflows to follow in working with seismic attributes; new methods of calculating certain new attributes which we feel to be useful; and new theoretical approaches to certain petrophysical properties. We are using data from Wyoming, North Texas, South Texas, and the Gulf of Mexico offshore of Louisiana. These environments provide a diverse array of physical conditions and rock types, and a variety of interpretation methods to be applied to them. The Wyoming field is a very difficult one, including alternating layers of thin beds of coals, shales, and hard sandstones, and there may be an observable effect due to hydrocarbon production; we are using this field as the ''test'' of those techniques and methods we have developed or that we prefer based on our work on the other fields. Work on this field is still underway, although progressing nicely. The work on the public domain data sets in Texas, Boonsville and Stratton, is complete except for some minor additional processing steps, and final write-ups are underway. The work on the Gulf of Mexico field has been completed to the extent originally planned, but it has led us to such important new observations and discoveries that we have expanded our original scope to include time-lapse studies and petrophysical aspects of pressure changes; work on this expanded scope is continuing. Presentations have been made at professional-society meetings, company offices, consortium workshops, and university settings. Papers, including one review paper on ''Reservoir Geophysics'' have been published. Several Master's theses, which will spin off

  5. Experimental Results of the Sensitivity of a Low Noise Aperture Array Tile for the SKA

    CERN Document Server

    Woestenburg, E E M; Ivashina, M V

    2011-01-01

    Aperture arrays have been studied extensively for application in the next generation of large radio telescopes for astronomy, requiring extremely low noise performance. Prototype array systems need to demonstrate the low noise potential of aperture array technology. This paper presents noise measurements for an Aperture Array tile of 144 dual-polarized tapered slot antenna (TSA) elements, originally built and characterized for use as a Phased Array Feed for application in an L-band radio astronomical receiving system. The system noise budget is given and the dependency of the measured noise temperatures on the beam steering is discussed. A comparison is made of the measurement results with simulations of the noise behavior using a system noise model. This model includes the effect of receiver noise coupling, resulting from a changing active reflection coefficient and array noise contribution as a function of beam steering. Measurement results clearly demonstrate the validity of the model and thus the concept ...

  6. New method for calibration of sun photometers

    Institute of Scientific and Technical Information of China (English)

    H.H.Asadov; I.G.Chobanzadeh

    2009-01-01

    A new method for calibration of sun photometers based on Bouguer-Beer law is proposed.The developed basic equation of calibration makes it possible to formulate the derivative methods of calibration on the basis of photometric measurements upon optical air masses,the ratio of which is an integer number.

  7. 48 CFR 908.7113 - Calibration services.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Calibration services. 908... ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Acquisition of Special Items 908.7113 Calibration services. Orders for calibration services may be placed with the National Institute of...

  8. Net analyte signal calculation for multivariate calibration

    NARCIS (Netherlands)

    Ferre, J.; Faber, N.M.

    2003-01-01

    A unifying framework for calibration and prediction in multivariate calibration is shown based on the concept of the net analyte signal (NAS). From this perspective, the calibration step can be regarded as the calculation of a net sensitivity vector, whose length is the amount of net signal when the

  9. A Novel T-Fed 4-Element Quasi-Lumped Resonator Antenna Array

    Directory of Open Access Journals (Sweden)

    S.S. Olokede

    2014-06-01

    Full Text Available In this paper, electrically small corporately T-fed quasi-lumped element resonator antenna array is investigated. The radiating element, a quasi-lumped element resonator is excited by a novel semi hybrid ring-like T-shaped corporate feed network. The characteristics losses due to Ohmic and discontinuities along the feed line which invariably constitutes complex feed structures are mitigated at the instance of the proposed antenna. Technique to implement the compact array with the intent to enhance the gain is presented. The operation dynamics of the feed along with its theoretical explanation is also reported. Findings indicates that the measured gain is 10.97 dBi for antenna of an estate area of about 0.677λ_0 × 1.257λ_0 sq. mm. Valuable insight to the optimum design in terms of compactness, good gain, and ease of fabrication is documented.

  10. A novel single-step, multipoint calibration method for instrumented Lab-on-Chip systems

    DEFF Research Database (Denmark)

    Pfreundt, Andrea; Patou, François; Zulfiqar, Azeem;

    2014-01-01

    . The pitfalls of PoC system adoption can be addressed early in the system design phase. They require a multidisciplinary design approach supported by systems engineering tools and methods. Considering this, we here present both a model and an implementation of a simple and rapid calibration scheme...... specifically addresses the important interfaces between a novel microfluidic unit to integrate the sensor array and a mobile-device hardware accessory. A multi-point calibration curve is obtained by generating a defined set of reference concentrations from a single input. By consecutively splitting the flow...

  11. Radio Astronomy Transformed: Aperture Arrays - Past, Present & Future

    CERN Document Server

    Garrett, Michael A

    2012-01-01

    I review the early development of Aperture Arrays and their role in radio astronomy. The demise of this technology at the end of the 1960's, and the reasons for the rise of parabolic dishes is also considered. The parallels with the Antikythera mechanism (see these proceedings) as a lost technology are briefly presented. Aperture Arrays re-entered the world of radio astronomy as the idea to build a huge radio telescope with a collecting area of one square kilometre (the Square Kilometre Array, SKA) arose. Huge ICT technology advances had transformed Aperture Arrays in terms of their capability, flexibility and reliability. In the mid-1990s, ASTRON started to develop and experiment with the first high frequency aperture array tiles for radio astronomy - AAD, OSMA, THEA & EMBRACE. In the slipstream of these efforts, Phased Array Feeds (PAFs) for radio astronomy were invented and LOFAR itself emerged as a next generation telescope and a major pathfinder for the SKA. Meanwhile, the same advantages that apertu...

  12. Corporate array of micromachined dipoles on silicon wafer for 60 GHz communication systems

    KAUST Repository

    Sallam, M. O.

    2013-03-01

    In this paper, an antenna array operating at 60 GHz and realized on 0.675 mm thick silicon substrate is presented. The array is constructed using four micromachined half-wavelength dipoles fed by a corporate feeding network. Isolation between the antenna array and its feeding network is achieved via a ground plane. This arrangement leads to maximizing the broadside radiation with relatively high front-to-back ratio. Simulations have been carried out using both HFSS and CST, which showed very good agreement. Results reveal that the proposed antenna array has good radiation characteristics, where the directivity, gain, and radiation efficiency are around 10.5 dBi, 9.5 dBi, and 79%, respectively. © 2013 IEEE.

  13. Towards Truly Boolean Arrays in Data-Parallel Array Processing

    NARCIS (Netherlands)

    C. Grelck; H. Luyat

    2013-01-01

    We investigate several dense bit-wise implementations of Boolean arrays in the context of the functional data-parallel array programming language SAC. A particular problem arises in compiler or directive based parallelisation as the scheduling of loops over Boolean arrays is unaware of the restricte

  14. A Three-Frequency Feed for Millimeter-Wave Radiometry

    Science.gov (United States)

    Hoppe, Daniel J.; Khayatian, Behrouz; Sosnowski, John B.; Johnson, Alan K.; Bruneau, Peter J.

    2012-01-01

    A three-frequency millimeter-wave feed horn was developed as part of an advanced component technology task that provides components necessary for higher-frequency radiometers to meet the needs of the Surface Water and Ocean Topography (SWOT) mission. The primary objectives of SWOT are to characterize ocean sub-mesoscale processes on 10-km and larger scales in the global oceans, and to measure the global water storage in inland surface water bodies, including rivers, lakes, reservoirs, and wetlands. In this innovation, the feed provides three separate output ports in the 87-to- 97-GHz, 125-to-135-GHz, and 161-to-183- GHz bands; WR10 for the 90-GHz channel, WR8 for the 130-GHz channel, and WR5 for the 170-GHz channel. These ports are in turn connected to individual radiometer channels that will also demonstrate component technology including new PIN-diode switches and noise diodes for internal calibration integrated into each radiometer front end. For this application, a prime focus feed is required with an edge taper of approximately 20 dB at an illumination angle of 40 deg. A single polarization is provided in each band. Preliminary requirements called for a return loss of better than 15 dB, which is achieved across all three bands. Good pattern symmetry is also obtained throughout all three-frequency bands. This three-frequency broadband millimeter-wave feed also minimizes mass and provides a common focal point for all three millimeter-wave bands.

  15. Black Holes Have Simple Feeding Habits

    Science.gov (United States)

    2008-06-01

    properties of these black holes should be very helpful. In addition to Chandra, three radio arrays (the Giant Meterwave Radio Telescope, the Very Large Array and the Very Long Baseline Array), two millimeter telescopes (the Plateau de Bure Interferometer and the Submillimeter Array), and Lick Observatory in the optical were used to monitor M81. These observations were made simultaneously to ensure that brightness variations because of changes in feeding rates did not confuse the results. Chandra is the only X-ray satellite able to isolate the faint X-rays of the black hole from the emission of the rest of the galaxy. This result confirms less detailed earlier work by Andrea Merloni from the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany and colleagues that suggested that the basic properties of larger black holes are similar to the smaller ones. Their study, however, was not based on simultaneous, multi-wavelength observations nor the application of a detailed physical model. These results will appear in an upcoming issue of The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

  16. A conductometric indium oxide semiconducting nanoparticle enzymatic biosensor array.

    Science.gov (United States)

    Lee, Dongjin; Ondrake, Janet; Cui, Tianhong

    2011-01-01

    We report a conductometric nanoparticle biosensor array to address the significant variation of electrical property in nanomaterial biosensors due to the random network nature of nanoparticle thin-film. Indium oxide and silica nanoparticles (SNP) are assembled selectively on the multi-site channel area of the resistors using layer-by-layer self-assembly. To demonstrate enzymatic biosensing capability, glucose oxidase is immobilized on the SNP layer for glucose detection. The packaged sensor chip onto a ceramic pin grid array is tested using syringe pump driven feed and multi-channel I-V measurement system. It is successfully demonstrated that glucose is detected in many different sensing sites within a chip, leading to concentration dependent currents. The sensitivity has been found to be dependent on the channel length of the resistor, 4-12 nA/mM for channel lengths of 5-20 μm, while the apparent Michaelis-Menten constant is 20 mM. By using sensor array, analytical data could be obtained with a single step of sample solution feeding. This work sheds light on the applicability of the developed nanoparticle microsensor array to multi-analyte sensors, novel bioassay platforms, and sensing components in a lab-on-a-chip. PMID:22163696

  17. A Conductometric Indium Oxide Semiconducting Nanoparticle Enzymatic Biosensor Array

    Science.gov (United States)

    Lee, Dongjin; Ondrake, Janet; Cui, Tianhong

    2011-01-01

    We report a conductometric nanoparticle biosensor array to address the significant variation of electrical property in nanomaterial biosensors due to the random network nature of nanoparticle thin-film. Indium oxide and silica nanoparticles (SNP) are assembled selectively on the multi-site channel area of the resistors using layer-by-layer self-assembly. To demonstrate enzymatic biosensing capability, glucose oxidase is immobilized on the SNP layer for glucose detection. The packaged sensor chip onto a ceramic pin grid array is tested using syringe pump driven feed and multi-channel I–V measurement system. It is successfully demonstrated that glucose is detected in many different sensing sites within a chip, leading to concentration dependent currents. The sensitivity has been found to be dependent on the channel length of the resistor, 4–12 nA/mM for channel lengths of 5–20 μm, while the apparent Michaelis-Menten constant is 20 mM. By using sensor array, analytical data could be obtained with a single step of sample solution feeding. This work sheds light on the applicability of the developed nanoparticle microsensor array to multi-analyte sensors, novel bioassay platforms, and sensing components in a lab-on-a-chip. PMID:22163696

  18. A Conductometric Indium Oxide Semiconducting Nanoparticle Enzymatic Biosensor Array

    Directory of Open Access Journals (Sweden)

    Tianhong Cui

    2011-09-01

    Full Text Available We report a conductometric nanoparticle biosensor array to address the significant variation of electrical property in nanomaterial biosensors due to the random network nature of nanoparticle thin-film. Indium oxide and silica nanoparticles (SNP are assembled selectively on the multi-site channel area of the resistors using layer-by-layer self-assembly. To demonstrate enzymatic biosensing capability, glucose oxidase is immobilized on the SNP layer for glucose detection. The packaged sensor chip onto a ceramic pin grid array is tested using syringe pump driven feed and multi-channel I–V measurement system. It is successfully demonstrated that glucose is detected in many different sensing sites within a chip, leading to concentration dependent currents. The sensitivity has been found to be dependent on the channel length of the resistor, 4–12 nA/mM for channel lengths of 5–20 µm, while the apparent Michaelis-Menten constant is 20 mM. By using sensor array, analytical data could be obtained with a single step of sample solution feeding. This work sheds light on the applicability of the developed nanoparticle microsensor array to multi-analyte sensors, novel bioassay platforms, and sensing components in a lab-on-a-chip.

  19. Scattering cross section of unequal length dipole arrays

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents a detailed and systematic analytical treatment of scattering by an arbitrary dipole array configuration with unequal-length dipoles, different inter-element spacing and load impedance. It provides a physical interpretation of the scattering phenomena within the phased array system. The antenna radar cross section (RCS) depends on the field scattered by the antenna towards the receiver. It has two components, viz. structural RCS and antenna mode RCS. The latter component dominates the former, especially if the antenna is mounted on a low observable platform. The reduction in the scattering due to the presence of antennas on the surface is one of the concerns towards stealth technology. In order to achieve this objective, a detailed and accurate analysis of antenna mode scattering is required. In practical phased array, one cannot ignore the finite dimensions of antenna elements, coupling effect and the role of feed network while estimating the antenna RCS. This book presents the RCS estimati...

  20. Concurrent array-based queue

    Energy Technology Data Exchange (ETDEWEB)

    Heidelberger, Philip; Steinmacher-Burow, Burkhard

    2015-01-06

    According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.